Chemical & Biological Investigation of Acacia auriculiformis
Chapter 1 INTRODUCTION
| 1.1 Rationale of the work |
Medicinal plant formed the basis and foundation stone of diseases from the very beginning of human civilization. Medicinal component from plants play many important roles in traditional medicine. People in all around the worlds have long been applied poultices and imbibed infusions of hundreds, if not thousands, of indigenous plants, dating back to prehistory (cowan, 1999). It is estimated that there are about 2,500,000 species of higher plants and the majority of these have not been investigated in details for their pharmacological activities (ram et al., 2003). In developing countries, about 80% of the population relies on traditional medicine for their primary health care needs (matu and Staden, 2003).
Previously the plant medications in the crude form exhibited many unwanted effects due to the presence of some toxic compounds beyond the active constituents. So, the purpose of extensive phytochemical study is to isolate the active constituents in the pure form to avoid unwanted effect and to ensure safe use of herbal medicines.
A medicinal plant represents a rich source of new molecules with pharmacological properties, which are lead compounds for the development of new drugs. The importance of plants in search of new drugs is increasing with the technological advancement of medicinal sciences. Many chemical compounds of diversified nature from plants often played an important role to give a new direction for laboratory synthesis of many new classes of drug molecules (Avram et al., 1974). In some cases, the plant components become the starting material in the synthetic process of industrial production of many drug molecules. As for example, the use of sterol diosgenin isolated from Mexican Yam for laboratory synthesis of oral contraceptive progesterone reduced the cost of progesterone from a value of $80 per gm to $1.75 per gm (Avram et al., 1974). Sometimes the crude drug containing several constituents was found to be ineffective in case of therapy for which it was used traditionally. The phytochemical investigation of periwinkle plant Vinca rosea (Avram et al., 1974), once used traditionally as an anti-diabetic drug was found to contain hypoglycemic alkaloid principles in minute quantities but it was found to contain anticancer principle vinca alkaloid in a high yield. The dried seeds of the plant Amni visanaga was used as a diuretic and antispasmodic in renal colic in the Eastern Mediterranean countries and in Arabia, but the research carried out by G. V. Anrep and coworkers (Anrep et al., 1949) resulted in the isolation Khelin, a component having the vasodilator effect. Khelin appeared as an anti-anginal drug after subsequent clinical trial. The research on Rauwlfia serpentine, which was traditionally used as an antidote for snake bite, revealed the presence of an antihypertensive agent reserpine (Vakil et al., 1949).
Ricin, a toxin ( one milligram of ricin toxin can kill an adult) produced by the beans of Ricinous Communis, had been found to be effectively couple tumor targeted monoclonal antibiotics and had proved to be a very potent antitumor drug (Gupta, 1992). Further HIV inhibitory activity has been observed in some novel coumarins (complex angular pyranocoumarins) isolated from calophyllum lanigerum and glycerrhizin (from Glycerrhiza species). Hypericin from Hypercium species is an anti cancer agent. Taxol is another exemple of one of the most potent anti tumor agent found from Taxus bravifolia. Thus phytochemical research on medicinal plants might open the door for many unknown therapeutic choices.
The isolated plant constituents having pharmacologic interest may be used as a model for synthesizing that compound or a series of its derivatives for finding out an ideal drug to improve selectivity of action. Such a model was cocaine, an alkaloid having anesthetic activity. Cocaine was isolated from coca leaves. Extensive pharmacological screening of this plant constituent led to recognize its central stimulant and addictive properties later on. Using the model of cocaine, several synthetic dialkylaminoalkyl-aminobenzoates were synthesized; one of these synthetic compounds was procaine, which displaced cocaine due to lack of addictive properties shown by cocaine. Due to relatively low therapeutic index of procaine, search of new synthetic products lead to the synthesis of lidocaine, tetracaine and dibucaine, which seem to better than procaine. But the basis of this search of ideal anesthetic having high therapeutic index and free from addictive properties, though still not fruitful, was isolation of cocaine from coca leaves (Avram et al., 1974).
Since chemical constituents of medicinal plants, particularly the secondary metabolites (alkaloids sterols, terpenes, flavonoids, saponins, glycosides, cyanogenics, tannins, resins, lactones, quinines, volatile oils etc.) have profound pharmacological action on animal systems and organs; they are capable of mitigating sufferings, curing ailments, and healing wounds cuts burns.
It is evident from the above discussion that pharmacological studies of crude extract are required after phytochemical investigation. Without pharmacological studies phytochemical studies alone can provide the chemical constituents of plants that may or may not have the therapeutic value. That is why Dr. Kurt Hosttetmann (Irvine, 1995) of University of Lausanne, Switzerland gave emphasis on the biological and pharmacological analysis might be a rational approach. According to world health organization (WHO), herbal medicines composed mainly of medicinal plants are still curing diseases of estimated 1.5 billion (currently it is said to be 3.5 billion, i.e, 88%) of the world population (said, 1995). Natural products and related drugs are used to treat 87% of all categorized human diseases including bacterial infections cancer and immunological disorders (Newman et, al; 2007). About 25% of prescribed drugs in the world originate from plants (Rates SMK; 2001) and over 3000 species of plant have been reported to have anti cancer properties. In developing countries, about 80% of the population relies on traditional medicine for their primary health care (matu and Staden, 2003). Whatever progress science might have made in the field of medicine over the years, plants still remain the primary source of many important drugs used in modern medicine & contributing to the development of synthetic drugs & medicine in a numerous of ways as stated below:
· Novel structures of biologically active chemical compounds, isolated from plant sources, often prompt the chemists to carry out their total synthesis.
· Synthetic drugs with similar or more potent therapeutic activity are often prepared by molecular modification of the plant-derived compounds with known biological activities.
· Various analogues and derivatives of plant constituents are synthesized to study SAR for getting better drugs.
In fact some of the plant constituent possessing a wide range of pharmacological are their impossible or to difficult to synthesize in the laboratory. A phytochemist uncovering these resources is producing useful material for screening programs for drug discovery. Outgrowth of newer diseases is also leading the scientists to go back to nature for producing newer effective drug molecules.
Recently developed genetic engineering in plants has further increased their importance, in the field of medicine for example in the production of antibiotics by expression of an appropriate gene in the plant. By using these techniques it is possible to modify the activity or regulates the properties of the key enzymes responsible for the production of secondary metabolites. Thus by knowing the potential resources it is possible to increase the content of the active compounds (owen et al., 1992) and in the future genes responsible for very specific biosynthetic processes may be encoded into host organism to facilitate difficult synthetic transformation.
Thus plants are considered as one of the most important and interesting subjects that should be explored for the discovery and development of newer and safer drug candidates.
| 1.2 PURPOSE OF THE STUDY |
Tropical Bangladesh is blessed with numerous kinds of medicinal plants and many of them have medicinal value. Majority of our population has to rely upon indigenous system of medication from economic point of view. The high cost of imported conventional drugs and inaccessibility to western health care facility, imply that traditional mode of health care that is affordable and available to rural people. On the other hand, even when western health care facilities are available traditional medicine is viewed as an efficient and an acceptable system from a cultural perspective (munguti, 1997) and as a result traditional medicine usually exist side by side with western form of health care.
Medicinal plants are rich sources of bioactive compounds and thus serve as important raw materials for drug development. However a very little are known about the chemical constituents of these plants. Identification and isolation of the active constituents from traditionally used phytotherapy can ensure the health care of the poor people. In addition, herbal medicine could be scientifically modified for better pharmacological activity and to establish safe and effective drugs and the rationality of the present study lies in meeting the challenges in developing herbal medicine which needs a systematic research on indigenous medicinal plants for the welfare of the humanity. Phytochemical investigation and isolation of active components in the pure form thus become necessary to avoid untoward effects and to ensure safe use of herbal medicines.
Therefore, studies on the isolation and characterization of the medicinally active compounds from these plants are very important for the well being of human society.
Bangladesh is a good repository of medicinal plants belonging to various families including Leguminosae. The Leguminosae Species contain a wide range of pharmacologically active compounds which are very useful and effective as astringent, anti-dysenteric, anti-protozoal, anthelmintic and antipyretic. These compounds are also useful in itching, eczema, diarrhea, hemorrhage, psoriasis, inflammation, leprosy, ulcer, sore throat, leucorrhoea, diabetes mellitus, impotency, piles and syphilitic affections of mouth and are effective in urinogenital disorders. Although uses of some of these species are based on old and new experiences and clinical data, many of them have no foundation whatsoever.
There are several familiar approaches for lead searching from plants (Fig:1.1) and isolate bioactive compounds utilized in three basic ways (Cox, P.A.,1994):
· Unmodified natural plant products where ethno-medial uses suggested clinical efficacy, e.g.,digitalis.
· Unmodified natural plant products of which the therapeutic efficacy was only remotely suggested by indigenous plant use, e.g.,vincristine.
· Modified natural or synthetic substances based on a natural product used in folk medicine, e.g, aspirin.
Figure 1.1: Lead compound search & utilization from plants.
The work described in this dissertation is an attempt to isolate and characterize the chemical constituents of an indigenous medicinal plant Acacia auriculiformis (family: liguminosae) and to evaluate the possible microbiological and toxicological profiles of the crude extracts is the primary objective of the present study
1.2.1 Present study protocol
The present study was designed to isolate pure compounds as well as to observe biological activities of the isolated pure compounds with crude extract and their different fractions. The study protocol consisted of the following steps:
S Successive cold extraction of the powdered leaves of the plant with methanol
respectively.
S Fractionation of the crude methanol extract by solvent-solvent extraction process into Petroleum ether fraction, carbon tetrachloride fraction and chloroform fraction.
S Fractionation of the carbon tetrachloride soluble fraction by column chromatography (CC).
S Fractionation of the Chloroform soluble fraction by column chromatography (CC).
SIsolation and purification of compounds from the selected column fractions
S Determination of the structure of the isolated compounds with the help of
1H NMR, 13C NMR, COSY, HSQC and HMBC spectroscopy.
S Observation of in vitro antimicrobial activity of crude extracts, fractions and
column fractions.
S Brine shrimp lethality bioassay and determination of LC50 for crude extract,
fractions and column fractions.
S Evaluation of Assaying free radical scavenging activity & determination of IC50 for crude extract, fractions and compounds.
1.2.2 The plant family: Leguminosae
Any of about 18,000 species in about 650 genera of flowering plants that make up the order Fabales, consisting of the single family Leguminosae, or Fabaceae (the pea family).
The term also refers to their characteristic fruit, also called a pod. Legumes are widespread on all habitable continents. Leaves of many members appear feathery, and flowers are almost universally showy. In economic importance, this order is surpassed only by the grass and sedge order (Cyperales). In the production of food, the legume family is the most important of any family. The pods are part of the diet of nearly all humans and supply most dietary protein in regions of high population density. In addition, legumes perform the invaluable act of nitrogen fixation . Because they contain many of the essential amino acids, legume seeds can balance the deficiencies of cereal protein. Legumes also provide edible oils, gums , fibers, and raw material for plastics, and some are ornamentals. Included in this family are acacia, alfalfa, beans, broom, carob, clover, cowpea, lupine, mimosa, peas, peanuts, soyabeans, tarmarind and vetch.
1.2.3 Classification of Kingdom Plantae down to family leguminosae.
| Kingdom | Plantae– Plants |
| Subkingdom | Tracheobionta– Vascular plants |
| Superdivision | Spermatophyta– Seed plants |
| Division | Magnoliophyta– Flowering plants |
| Class | Magnoliopsida– Dicotyledons |
| Subclass | Rosidae |
| Order | Fabales |
| Family | Fabaceae– Pea family |
| Genus | Acacia Mill.– acacia |
| Species | Acacia auriculiformis A. Cunn. ex Benth.– earleaf acacia |
The plant under investigation is Acacia auriculiformis belonging to the family Leguminosae.
This is one of the largest and most useful plant families. – 18,000 species, distributed almost throughout the world. It includes many well-known vegetables particularly of temperate regions (Beans, Peas), ornamental trees in tropical regions (Bauhinia, Flamboyant, Cassia), fodder crops (Clover, Lucerne) and weeds (Vetches and Trefoils), and their growth habits vary from ground cover and aquatic to shrubs, climbers and trees. Many species of trees in this family are important for their timber.
Leguminosae, pea family– a large family of trees, shrubs, vines, and herbs bearing bean pods; divided for convenience into the subfamilies Caesalpiniaceae; Mimosaceae; Papilionaceae.
These Families have been formed by splitting the old Leguminosae Family on the basis of flower shape, type of leaves, and number of stamens.
The Papilionaceae Family is found in temperate, sub-tropical and tropical areas. Members of this Family are mostly herbs, but with some trees and shrubs, and have irregular flowers forming a butterfly or pea-flower shape, with the lateral petals enclosed by the standard when in bud, with ten stamens. The family Papilionaceae includes the following genera:
Amorpha, Anthyllis, Astragalus, Baptisia, Caragana, Clianthus, Colutea, Cytisus, Dolichos, Erythrina, Genista, Glycyrrhiza, Hardenbergia, Indigofera, Kennedia, Laburnum, Lathyrus, Lotus, Lupinus, Medicago, Mucuna, Ononis, Oxytropis, Parochetus, Phaseolus, Pueraria, Robinia, Sesbania, Sophora, Sutherlandia, Trifolium, Trigonella, Vicia, Wisteria.
The Mimosaceae Family contains mainly tropical and sub-tropical trees and shrubs, with regular flowers with ten or more stamens. The Mimosoideae are characterised by their small, regular (actinomorphic) flowers crowded together, generally into spikes or heads which resemble a pom-pom. The stamens have become the most attractive part of the flower, the five petals inconspicuous. The leaves are predominately bipinnate. The family Mimosaceae includes the following genera:
Acacia, Albizia, Calliandra, Mimosa, Paraserianthes.
Certain Acacia species are extremely important economically. An extract from the bark of the Golden Wattle (Acacia pycnantha) is used in tanning, several species, such as Australian Blackwood (e.g. Acacia melanoxylon) provide useful timbers and some (e.g. Acacia senegal) yield commercial gum arabic, which is used in a wide range of industrial processes.
The Caesalpiniaceae Family is also mainly tropical and sub-tropical trees and shrubs, with irregular flowers and ten or fewer stamens. The family Caesalpiniaceae includes the following genera:
Bauhinia, Caesalpinia, Cassia, Ceratonia, Cercis, Delonix, Gleditsia, Schizolobium, Schotia, Tamarindus.
The seedpods of all these Families are the same – they are all legumes – pods, formed from a superior ovary, usually containing several seeds, which splits along both sides. In some tropical species, the seedpods are very large and woody.
The seeds of many members of these Families are the distinctive kidney-shape generally referred to as ‘beans’, with a visible scar where the seed was attached to the seedpod. Many are quite large, and some are brightly-coloured.
1.2.4 Members of Leguminosae family
The plants belonging to the family Leguminosae, which are available all over the world, are shown in the Table 1.1.
Table 1.1 Leguminosae species available in the world.
| Leguminosae | |||
| Latin Name | Common Name | Synonyms | Medicinal |
RatingAcacia aneuraMulga Acacia 0Acacia coriaceaWiry Wattle 0Acacia cultriformisKnife-Leaf Wattle 0Acacia dealbataMimosaAcacia decurrens dealbata0Acacia decurrensGreen WattleMimosa decurrens1Acacia farnesianaSweet AcaciaAcacia smallii, Mimosa farnesiana2Acacia longifoliaSidney Golden WattleMimosa longifolia0Acacia melanoxylonBlackwood 1Acacia mucronataNarrow-Leaf Wattle 0Acacia paradoxaKangaroo ThornAcacia armata0Acacia podalyriifoliaQueensland Silver Wattle 0Acacia pycnanthaGolden Wattle 0Acacia retinodesSwamp Wattle 0Acacia salignaBlue-Leaved WattleAcacia cyanophylla0Acacia sophoraeCoastal Wattle 0Acacia verticillataPrickly Moses 0Adesmia lotoides 0Albizia julibrissinMimosaAcacia julibrissin2Alhagi manniferaManna TreeHedysarum alhagi2Alhagi maurorumCamel ThornAlhagi camelorum, Alhagi persarum, Alhagi pseudalhagi, Hedysarum pseudalhagi2Amorpha canescensLead Plant 2Amorpha fruticosaFalse Indigo 0Amorpha nanaDwarf IndigobushAmorpha microphylla1Amphicarpaea bracteataHog PeanutAmphicarpaea monoica, Falcata comosa1Amphicarpaea edgeworthii Amphicarpaea japonica, Falcata japonica0Amphicarpaea pitcheriHog PeanutAmphicarpaea bracteata comosa, Falcata pitcheri0Anthyllis vulnerariaKidney Vetch 2Apios americanaGround NutApios tuberosa1Apios fortunei 1Apios priceana Glycine priceana0Arachis hypogaeaPeanut 2Aspalathus linearisRooibosAspalathus contaminatus, Borbonia pinifolia3Astragalus aboriginorumIndian MilkvetchAstragalus australis0Astragalus adscendensPersian MannaAstracantha adscendens0Astragalus boeticusSwedish Coffee 0Astragalus brachycalyx 0Astragalus canadensisCanadian MilkvetchAstragalus carolinianus2Astragalus carduchorum 0Astragalus chartostegius 0Astragalus chinensisHua Huang Qi 2Astragalus christianus 0Astragalus complanatusBei Bian Huang Qi 2Astragalus crassicarpusGround PlumAstragalus caryocarpus, Astragalus mexicanus, Astragalus succulentus, Geoprumnon succulentum1Astragalus creticus 0Astragalus densissimus 0Astragalus diphysusSpecklepod MilkvetchAstragalus lentignosus diphysus0Astragalus echinus Astracantha echinus0Astragalus edulis Tragacantha edulis0Astragalus exscapus 1Astragalus floridusDuo Hua Huang Qi 2Astragalus florulentus Astracantha florulenta0Astragalus garbancillo 0Astragalus globiflorus Astracantha globiflora, Astragalus elymaiticus0Astragalus glycyphyllosMilk Vetch 0Astragalus gummiferTragacanthAstracantha gummifera3Astragalus hamosus 2Astragalus henryiQin Ling Huang Qi 0Astragalus hoantchyWu La Te Huang Qi 1Astragalus kurdicus Astracantha kurdica0Astragalus leioclados Astracantha leioclados0
1.2.5 The Genus Acacia A. – A brief discussion
Acacia is the common name for the plants of genus Acacia of the family Leguminosae. Acacia is a large genus with 900 species (Hatchinson 1964, Nasir et al., 1973) approximately 700 of which are native to Australia. The remainder occurs mainly in tropical and sub-tropical regions of Africa, Asia and America. Acacia have the capabilities to grow under the xerophytic conditions and to survive under extreme droughts, is an important feature of the genus Acacia. The trees of Acacia are exceedingly hardy and they prefer to grow under the severest natural conditions than in the cultivated places. These can grow in sandy, saline and even on water–logged soils (PCSIR 1987). In deserts of Asia and Africa, goats and camel browse on leaves and young shoots of Acacias. In Australia some species also serve as forage for cattle and sheep.
The name is derive from the Greek AKAZO which means “I Sharpen”, in allusion to the species of thorny bushes or small trees also called Mimosas are known as “thorn”, as “Kikar” in Indo-Pak and as Acacias in Asia and America. In Australia Acacias are known as many popular names, the principal one applying to the whole genus being the “Wattle”. Australian gave many names to different species of Acacias such as Myall, Mulga, Boree, Brigalow, Miljee, Windi, Cooba, Gidgee, Euonung and Yarram. In Pakistan different Acacias were known as babul, phulai, khair, katha, khor and raru etc.
The wood of Acacia trees is in some cases very valuable, though usually small in making railway carriage, wheels, handles, furniture and is the best of making charcoal (Gohl 1975, Lexicon Universal Encyclopedia 1987). The bark of some Acacia is extensively used for tanning leather (Olivannan et al., 1966). In Australia and some parts of Africa and Asia, seeds and pods are used by human for food (Tanaka 1976). Tanaka reported the edible uses of 56 species of Acacias (Nironala et al., 1984). Due to their large uptake of salts, Acacias are used for soil reclamation and to increase fertility through their high nitrogen fixation capability (Stravge 1977). The medicinal uses of the Acacias species are also known since time immemorial (Chowdhury et al., 1948, Lir 1936, Perry 1980 etc).
A large number of Acacias yield gum in greater lesser quantities. It exudes naturally from the trunk of the trees of wild, although this is often encouraged by making incisions in the trunk. The more the cuts, the more the gum is expels, which on exposure to air hardens into yellowish white transparent beads. The finest gum Acacia or gum arabic is known as kordofan gum which comes from A.senegal, a small tree native to Africa, from Ethopia to sudan. Acacia gum is also has medicinal properties.
Table 1.2 .6Acacia species available in the world
| Acacia species | Height |
metres Width
metres Foliage Flowering A. acinacea 2.51.5greenGolden balls in springA. acuminata 52greenGolden in spikes springA. adunca 62greenVery showy late winterA. alata 21Spined phyllodesCream or gold aut-late springA. alleniana 53Thread
like/pendulousGolden balls mar to maA. araneosa 5-83-4greenSprays yellow
throughout yearA. argyrophylla 3-53Silver-greyGolden-yellow balls in
WinterA. aneura 5-105greenBright yellow spikesA. armata 22greenGold balls springA. aulacocarpa .5 – 8.5 – 8Blue/greenMidsummer to winterA. baileyana 5-85blue/greenYellow, late winterA. bancroftiorum as known as A. bancroftii 64Bluish 20cm longYellow ball sprays late
aut. to late winterA. beckleri 1-31-2Green/greyBright yellow late aut. to
mid winterA. bivenosa 1-31-3Green- glaucousYellow mid aut. to late
springA. boormanii 3-54grey/greenBright yellow, early
spring.A. brachystachya 2 – 62 – 6GlaucousYellow in axis of
phyllodes aut – late
winterA. browiniana 22Tiny bipinnate
with oblong
leafletsGolden ball flowers
larger then the leaves in
springA. brownii 11Prickly phyllodesGolden balls in slim
pedunclesA. buxifolia 32Green to
glaucousGolden balls in late
winter to springA calamifolia 2-42-4Grey-green with
bent tipPale yellow to goldenA. cardiophylla 1-31 To 3Pale greenBright yellow balls in
springA. cognata 1- 101 – 6Yellow- green to dark green
pendulousPale lemon/cream in springA. colletioides 1.5 or
more3Prickly with
yellow stem projectionsOrange or yellow in springA. complanata To 5m3Light green
phyllodes to 0cmDeep yellow spring to autumnA. conferta 22greenBright yellow autumn to
mid springA. continua 1-2To 1Hooked – spiky
blue-greenLarge golden balls early
springA. craspedocarpa 1 To 41 To 2.5GreyGolden spikes mainly in
springA. cultriformis 3-43blue/greenGolden spring,A. cyclops 1-61-6Blue/greenYellow in spring and
showyA. dealbata 5-208blue/greenBright yellow, late winter
to springA. deanei 5-103-5greenPale yellow, all yearA. decora 3-54grey/greenGolden yellow –early
spring.A. denticulosa 1-42-4Dark greenRod shaped golden in
springA. dimidiata 1 To 73Curved to one
side.Terminal sprays of
golden flowers in
autumnA. dentifera 2-43Blue/greenCream/yellow early –
mid springA. doratoxylon 6-10m6GreenGolden spikes in springA. drummondii 1.51GreenGolden, late winter –
mid springA. dunii To 7m Long 30cm glaucous to 20cm wideGolden balls year roundA. elata 10-208Brown/ greenCream, summerA. elongata 31.5Pale greenYellow to gold balls in
late winter – springA. erinacea 11.5Grey-greenYellow balls in winter-
springA. extensa 2 -32Long 20cm
phyllodes pale
greenLight golden – yellow
balls in springA.A. falciformis 1 To 123Grey-greenCream – yellow globes
Early summerA. falcata To 41-2Grey- green to
glaucous sickle
shapedCream in winterA. falvescens 4 – 201-3Pale greenCreamy globes late
autumn to early winterA. flexifolia 1 – 1.5.5-1Grey- greenSmall yellow balls in
winterA. floribunda 4-84-6GreenYellow, July-SeptA. genistifolia .6 – 31 To 2GreenLarge cream balls winter to early springA. glaucoptera To 1.5To 1.5GlaucousYellow globes in springA. gonocarpa .6 – 3.5.6 – 2GreenPale cream rods summer and again in winterA. gracilifolia 1-21-2Narrow greenPale gold in springA. guinetii .52.5Pale green-
Yellow tingeYellow winter – early springA. hakeoides To 4To 3GreenGolden in sprays winter
and springA. hemsleyi To 7m3-5GreenYellow rods in early
springA. hispidula 1-2m1-2GreenYellow balls all yearA. howittii 4-84GreenPale yellow, SpringA. inophloia 1 – 3.51- 2Greyish-greenBright yellow rods late winter to mid springA. iteaphylla 4-54Blue/greenPale yellow, Mar-AugA. kempeana 2- 52-5Grey to
blue/greenBright golden spikes
mid summer to springA. kettlewelliae 2 -102-5Silvery – green to
glaucousLight bright gold in late springA. lanigera 11Woolly narrow
green-bluishSmall balls in springA. latescens 3 – 103-5Sickle shaped
long leaves to
20cm pale greenCream balls in autumnA. leprosa 2-4To 2GreenYellow- orange in springA. leptostachya 1-51-5Green to slightly
glaucousGolden rods in winterA. longifolia 4-104-8GreenYellow, July-SeptA. macradenia 3 – 63 – 6Green with
reddish new
growthBright yellow winter and springA. mearnsii 10-2510Grey/greenPale yellow, springA. melanoxylon 5-305-15Grey/greenCream, July-OctA. merinthophora 4mTo 3mGrey/greenCreamy yellow rods in the leaf axis late autumn to early springA. montana 1 -41-4Bright green and
stickyGolden balls in springA. muelleriana 1 – 81 – 8Dark greenCream balls in springA. myrtifolia .5 – 3.5 – 3Dark greenCreamy/yellowA. notabilis To 3 mTo 3-4mGrey/green –
GlaucousGolden balls in springA. obliquinervia To 152-5mGrey/green to
slightly glaucousLemon to golden globes Late winter to early summerA. oncinocarpa To 5To 4Mid greenPale yellow rods in autumnA. papyrocarpa 3-42-3GreyYellow in springA. paradoxa 2-43-4PricklyYellow to bright yellow balls late winter to late springA. pendula 5-133-13Glaucous/greyYellow balls in springA. phasmoides 1-4To 4Glaucous/greyGolden-yellow rods in
springA. podalyriifolia 43blueGolden, July-Oct.A. pravissima 4-85-7Olive greenYellow, Sept.A. prominens 5-157Blue/greenLemon, Sept.A. pycnantha 4-104GreenYellow, July-Oct.A. retinodes 5- 85GreyCream-yellow balls in
winter-springA. rigens 23Grey-green
sticky, glossy.Golden balls in springA. rubida 1.5 – 51-4Green to GlaucousYellow in springA. saligna 4-105GreenYellow, Aug-Nov.A sophorae – see A. longifolia A sclerophylla To 23Glossy, sticky
greenGolden balls borne in the leaf axis in springA. siculiformis To 2 – 32-3Dark greenCream balls in springA. spectabilis 2 -4 up to 62-4Blue-green to
GlaucousGolden balls in springA. stricta 1- 5Suckering
habit 1-5Dullish greenStem clasping balls in springA. suaveolens 34Blue/greenPale, April-SeptA. terminalis 32Dark greenCream to yellow balls in autumn – winterA. torulosa 1.5 – 151-10Yellowish-greenBright yellow in winterA. triptera 3To 7Bluish-green,
sickle shapedGolden rods in springA. ulcifolia 1-21-2GreenCream, Mar-SeptA. umbellata 2-63 -6Light greenGolden rods in summerA. uncinata 33Grey-greenGolden rods in summerA. verniciflua 1-81-5GreenCream- yellow balls in
springA. verticilata 2-71-3GreenYellow, June-Dec.
1.2.6.1 Medicinal importance of Acacia species
Many Acacia species have important uses in traditional medicine. Most all of the uses have been shown to have a scientific basis, since chemical compounds found in the various species have medicinal effects. In Ayurvedic medicine , Acacia nilotica is considered a remedy that is helpful for treating premature ejaculation . A 19th century Ethiopian medical text describes a potion made from an Ethiopian species of Acacia (known as grar) mixed with the root of the tacha, then boiled, as a cure for rabies . An astringent medicine, called catechu or cutch, is procured from several species, but more especially from Acacia catechu, by boiling down the wood and evaporating the solution so as to get an extract.
Table 1.2.6.2 Medicinal plants of Leguminosae family available in Bangladesh
| BOTANIC NAME | LOCAL NAME |
| Abrus precatorius L. | Kunch, Rati, Chanyi, Kaich, Gungchi, Gujna |
| Agati grandif lora Desv. |
(Sesbania grandiflora (L.) Pers.) Bakphul, Agasta, Buko, Bak, AgatiCaesalpinia crista L.
(C. nuga L.) Let KantaCassia alata L. Dad Mardan, DadmariClitoria ternatea L. Aparajita, Nila AparajitaMimosa pudica L. Lajjabati, LajakSaraca indica L. AshokeTephrosia purpurea Pers. Bannil, Lohamori, Sarpunkha
1.2.6.3 Taxonomy of Acacia
Family: Fabaceae (Pea family) (Wagner et al. 1999).
Latin name: Acacia auriculiformis Cunn. ex Benth. (PIER 2002).
Synonyms: Racosperma auriculiforme (Benth.) Pedley (Randall 2002).
Common names: Earpod wattle, Papuan wattle, auri, earleaf acacia, northern black wattle, Darwin black wattle (GRIN 2002, PIER 2002).
Taxonomic notes: The genus Acacia is made up of about 1,200 species that are
widespread but with a large number in Australia (Wagner et al. 1999).
Nomenclature: The genus name is derived from akakia, the Greek name for Acacia arabica (Lam.) Willd., which is derived from akis, a Greek word meaning sharp point, in reference to the thorns of the plant (Wagner et al. 1999).
Acacias belong to the legume family (Fabaceae), the third largest family of flowering plants, including three subfamilies, 650 genera and 18,000 described species. All three subfamilies produce typical legume seed pods that either split open or remained closed at maturity, but their flowers are quite different. Acacia blossoms are not pea-like, and for this reason the genus is placed in the subfamily Mimosoideae, along with silk tree (Albizia), fairy duster (Calliandra) and mesquite (Prosopis). The flowers consist of an inconspicuous calyx and greatly reduced or no petals, with numerous, showy stamens. Acacia flowers are clustered together in small yellow or white globose heads, or in cylindrical spikes. In some species (A. baileyana) the flower clusters are produced in spectacular yellow masses, and in others (A. farnesiana) they are very fragrant, attracting numerous insect pollinators. The latter species is a spiny shrub native to the southwestern United States and Mexico. The flowers contain an essential oil used for perfumery in France
One of the most intriguing taxonomic features of the genus Acacia is its divergence into two major groups with entirely different leaf types. One group has fern-like, bipinnate leaves subdivided into numerous minute leaflets. It includes hundreds of species throughout Australia, Africa and the Americas. Another group has “simple” leaves that are not divided into leaflets. The leaves of this group are called phyllodes, and they are actually expanded or broadened petioles (leaf stalks) which have lost the upper pinnate portion. Seedlings of this group produce the ancestral pinnate leaf, gradually replaced by phyllodes. Pruned branches of some species often develop phyllodes bearing bipinnate leaves at their tips. The phyllode group also contains hundreds of species distributed throughout Australia and the Pacific Islands. In fact, one of these species is the magnificent “koa” tree (Acacia koa) native to Hawaii. The following chart shows the vegetative divergence in the genus Acacia:
Information about the investigated plant
1.2.6.4 General botanical data of Acacia auriculiformis
Botanical Name: Acacia auriculiformis.
Synonym: Acacia auriculaeformis
Local name: Akashmoni, sonazhuri
Family: Leguminosae
Description: Evergreen, unarmed tree to 15 m (50 ft) tall, with compact spread, often multi-stemmed; young growth glaucous. Quickly reaching a height of 40 feet and a spread of 25 feet, it becomes a loose, rounded, evergreen, open shade tree. It is often planted for its abundance of small, beautiful, bright yellow flowers and fast growth. Leaves alternate, simple, reduced to phyllodes (flattened leaf stalks), these blade-like, slightly curved, 11-20 cm (5-8 in) long, with 3-7 main parallel veins and a marginal gland near the base; surfaces dark green. The flattened, curved branchlets, which look like leaves, are joined by twisted, brown, ear-shaped seed pods. Flowers in loose, yellow-orange spikes at leaf axils or in clusters of spikes at stem tips; flowers mimosa-like, with numerous free stamens. Growing 6 to 8 feet per year, Acacia auriculiformis quickly grows into a medium-sized shade tree. This makes it a popular tree. However, it has brittle wood and weak branch crotches, and the tree can be badly damaged during wind storms. Prune branches so there is a wide angle of attachment to help them from splitting from the tree. Also be sure to keep the major branches pruned back so they stay less than half the diameter of the trunk. These techniques might increase the longevity of existing trees.
Fruit and seed description:
Fruit: Flat, dehiscent, somewhat woody pod, 6.5 cm long, 1.5 cm wide, strongly curved and with undulate margins. Fruits are twisted at maturity, splitting to reveal flat black seeds attached by orange, string like arils.
Seed: Shiny black or brown, encircled by a long, red or yellow funicle. There is 55,000-75,000 seeds/kg.
Flowering and fruiting habit:
The yellow flower spikes can be found on individual trees throughout the year but there is usually a distinct peak flowering season which may vary considerably with location. Pollination is carried out by a wide range of insects. Seed is produced at an early age and normally in large quantities.
Distribution:
Planted widely in the Old World for pulp and fuel wood, particularly in India and Southeast Asia; undergoing forestry trials in Africa and Central and South America (Pinyopusarerk 1990, Boland et al. 1991).
Figure 1.1 Seed with funicle, flowering branch and pod.
Figure 1.2 Forest tree form of Acacia auriculiformis. Bensbach River, Balamuk, Western
Provenance, Papua New Guinea.
Figure 1.3 Leaves of Acacia auriculiformis
Importance:
This plant is raised as an ornamental plant, as a shade tree and it is also raised on plantations for fuel wood throughout south-east Asia Oceania and in Sudan. Its wood is good for making paper, furniture and tools. It contains tannin useful in animal hide tanning. In India, its wood and charcoal are widely used for fuel. Gum from the tree is sold commercially, but it is said not to be as useful as gum arabic. The tree is used to make an analgesic by indigenous Australians. A decoction of the root is used to treat aches and pains and sore eyes; an infusion of the bark treated rheumatism (aborigines of Australia).
Extracts of Acacia auriculiformis heartwood inhibit fungi that attack wood. Aborigines of Australia have traditionally harvested the seeds of some acacia species as food as paste or baked into a cake because it assumed to be contains 25% more protein than common cereals like rice or wheat etc. Acacias were purposely introduced and planted in Southeast Asia and Oceania as a source of firewood and good quality charcoal (does not smoke), as well as timber for furniture and pulp for making paper (acacia produces high yields of pulp and produces strong paper. In India, the tree was cultivated to feed the lac insect, which produces a resinous secretion that is harvested to produce lacquer. Acacia has the potential to protect poor soils from erosion by its long root and revive their mineral content. Acacia can grow on poor soils including clay, limestone and unstable sand dunes, even soil tainted with uranium wastes.
Acacias recover wastelands, returning nutrients to poor soils and providing shade for other plants to take hold. They do not produce a lot of pollen or nectar as food, but their plentiful seed supply is a valuable food source for animals (mainly birds and also small mammals), particularly in dry places. Various insects eat their leaves and wood, and sugar gliders and squirrels may eat their sap.
1.2.6.5Previous phytochemical studies of the genus Acacia
All or a combination of the compounds below may be found in many flowering plants, including acacias. This is however a rather simplified treatment of a very complex subject, there being literally thousands of different compounds and metabolites in plants. The role or function, if any, is still debatable, protection against predation, end metabolites, plant hormones, pheromones, anti-fungal/ viral etc.
Carbohydrates, sugars and gums – Carbohydrates (sugars) are the products of photosynthesis that plants use as starting material for most of the other compounds in plants. Cellulose is a carbohydrate that most plants make and contain that gives plants their structure and strength; some parts of plants may be more than 50% cellulose. Gums are polysaccharidic (made from sugars) compounds, where various different sugars are joined together to form polymer like structures. Some acacias produce quite large amounts of gum from injuries or insect attack, some are edible; they can vary greatly in their water solubility, some becoming gelatinous and not really dissolving.
Terpenes, oils and resins
Generally water insoluble organic compounds, originally applied to substances made up of two 5-carbon units, the so called isoprene unit. Mono-terpenes are two units, sesquiterpenes are three units, diterpenes are four units, triterpenes six units etc. Different oils and terpenes may be found in the flowers and foliage, some acacia flower essential oils are used in perfumery. Most essential oils are mono or sesqui terpenes, resins are often more complex terpenoid mixtures that may also contain gums. There are some new terpinoids has been invented from Acacia auriculiformis. These includes-
Three new triterpenoid saponins, proacaciaside-I, proacaciaside-II and acaciamine isolated from the fruits of Acacia auriculiformis, were identified as acacic acid.
· (1 ? 6)-?- -glucopyranoside, acacic acid
· (1 ? 2)-?- -glucopyranoside and acacic acid
*(1 ? 6)-2-acetamido-2-deoxy-?- -glucopyranoside
* Acaciasides A and B, two novel acylated triterpenoid bisglycosides isolated from the fruits of Acacia auriculiformis, were respectively defined to be 3- -[?-D-glucopyranosyl (1?6) &{;?-L-arabinopyranosyl (1?2)&};- ?-D-glucopyranosyl]-21- -&{;6?S)-2?-trans-2?,6?-dimethyl-6?- -?-D-glucopyranosyl-2?,7?-octadienoyl&}; acacic acid 28- -?-L-rhamnopyranosyl (1?6) [?-D-xylopyranosyl (1?6) &{;?-L-arabinopyranosyl (1?2)&};-?-D-glucopyranosyl]-21- -[(6?S)-2?-trans-2?,6?- -&{;?-D-xylopyranosyl (1?2)-?-D-glucopyranosyl&};- 2?,7?-octadienoyl] acacic acid 28- -?-L-rhamnopyranosyl (1?6) [?-D-xylopyranosyl (1?2)]-?-D-glucopyranoside (2). The structural details were elucidated by a combination of fast-atom-bombardment mass spectrometry, 1H-, and 13C NMR spectroscopy, and some chemical transformations.
Fig : acaciaside-B
* The structure of a new triterpenoid trisaccharide isolated from the seeds of Acacia auriculiformis has been elucidated as acacic acid lactone-3-O-?-d-glucopyranosyl (1 ? 6)-[?-l-arabinopyranosyl (1 ? 2)]-?-d-glucopyranoside based on its spectral properties and some chemical transformations.
* The structural elucidation of auriculoside, a new flavan glucoside named -7,3?,5?-trihydroxy-4?-methoxyflavan 3?-glucoside; ?-spinasterol.from Acacia auriculiformis has been done, This is the third report of a flavan glycoside unsubstituted in the heterocyclic ring. Inventor-Shashi B. Mahato<href=”#aff1″>a, Bikas C. Pal<href=”#aff1″>a and Keith R. a Indian Institute of Chemical Biology 4, Raja S. C. Mullick Road, Jadavpur Calcutta-700032, India
FIG: list of New triterpinoid compound from isolated from Acacia Acacia mellifera–Inventor-
–
Constituent from Acacia cedilloi and Acacia gaumeri.–Inventor-Gwendeli G. pech, Gonjalo.j.mena
And leuvigillido.,mexico
Tannins – tannins are complex compounds based on tannic and gallic acid, very common in the wood, bark and foliage that are water soluble but react with proteins, this is what causes the astringency of many plants and is utilized to preserve leather in the tanning process. Acacia bark has been used as a source of tannins, some species having large amounts in the bark.
Glycoside – Is a general term for substances made up of a sugar residue (glucose unit) and another compound, such as a flavanoid, coumarin, steroid or terpene, collectively known as the aglycone. Glycosides are common in plants, there are quite a few that have a strong action on the body, including the heart, digestive and peripheral nervous system. ‘Cyanogenetic glycosides’ produce free HCN (cyanide) when reduced (digested?), and along with other glycosides, like the cardioactive glycosides can produce toxic even fatal results if enough is ingested, which may not be very much. About forty species from sub-genus Phyllodineae have been recorded as being cyanogenetic.
1.2.6.6 Glycoside reported from the acacia species
The glycoside kaempferol has been isolated from the flowers of A. discolour, A. linifolia, A. decurrens and A. longifolia, kaempferol is water soluble and yellow, and in these cases responsible for the color of the flowers ( J Petrie, Proc. Linn. Soc. NSW, #48: 356-67, 1923), and this may be the case with many, if not most acacia flowers. This compound has been found to be a diuretic (promotes urination) and natriuretic (causes sodium loss), increasing urine secretions and the functioning of the kid nay cells, increasing in turn, their permeability and circulation. The general result is that kidney function improves which helps the body to positively react to water retention and excessive blood glucose levels, both of which are secondary symptoms of diabetes (Winkelman, Ethnobotanical treatments of diabetes in Baja California norte. unpublished report, Arizona state uni, Tempe, Ariz. 1991). Some of the new glycosidic compounds isolated from these species are listed below-
· Myricetin -3,7-diglucoside
Kaempferol –7-glucoside , 3-glucoside (9) etc.
· Quercetin -3’-methyl ether (12) & 7-glucoside (13
Flavanoids
This is a term that is applied to compounds common in many plants and quite often responsible for the colours in wood, fruit and flowers.
1.2.7Flavanoids present in different species of acacia
The flavanoids of the heartwoods of Australian acacias has been the subject of some study. The studies have found that Australian acacias can be broadly divided into different groups depending on the flavanoids present in the wood. These groupings did not correspond exactly with the classification based on morphological differences. There were however some correlations with the Botrycephaleae forming a distinct group and Phyllodineae species with flowers in racemes having a similar flavanoid pattern. The Juliflorae and Plurinerves had a similar flavanoid pattern, the Juliflorae being a fairly well defined group, with a further small group in the Juliflorae having unique but related flavanoids. There was also a distinct group in the Phyllodineae that had unique flavanoids that give members of this group distinctively purple heartwood. There were some mixed results for some species in sections Phyllodineae , Plurinerves and Juliflorae , especially the tropical northern species.
Other studies of the free amino acids in the seeds of different species found that sub-genus Acacia was a distinct group different to sub-genus Phyllodineae and Acueiliferum, a sub-genus of mostly Asian, African and Central American species. There seemed to be some relationship between sub-genus Phyllodineae and Acueiliferum, with the addition of two more amino acids, one toxic, in the Acueiliferum species seeds compared to sub-genus Phyllodineae. Three extra Australian species of sub-genus Phyllodineae, a. confusa, a. simplex and a. kuauiensis also have been found contain these extra amino acids.
· (2,3-trans-3,4?,7,8-tetrahydroxyflavanone,
· Teracacidin,
· 4?,7,8,-trihydroxyflavanone)
Fig : structure of compound isolated from Acacia auriculiformis and other acacia species.
.
Figure 1.4 : Structures of falvonoids isolated from Acacia auriculiformis
( Leucodelphinidin <href=”#cite_ref-0″>^ A new flavan-3,4-diol from Acacia auriculiformis by paper ionophoresis, S. E. Drewes and D. G. Roux, 1966)
Alkaloids – is a general term for basic (alkaline) nitrogen containing organic compounds, generally bitter in taste and strong physiological action, many plant derived drugs and medicines are alkaloids, eg quinine, scopolomine, codiene, morphine, ephedrine, tryptamines etc. A lot of them can be potentially toxic, even fatal, especially when in the form of purified alkaloids extracted from plants, quite often only a small amount of the alkaloids can have a strong effect. Obviously some or at least the plants that contain them have proved immensely useful to people for disease and illness, for thousands of years.
1.2.8Alkaloids from the species of acacia
Alkaloids are relatively common in the leguminosae as a whole, and within the genus acacia in Australia alkaloids that have been reported include N, N-dimethyltryptamine, N-methyltryptamine, tryptamine, tetrahydroharman, N-methyl-tetrahydroharman, b-phenethylamine, N-methyl-b-phenethylamine, hordenine (N, N-dimethyl-4-hydroxy-b-phenethylamine), N-cinnamoylhistamine….. For the number of species, there has been little research on the alkaloids of Australian acacias, and like many studies of Australian plants there has been quite a lot of variability in the results. For example the root bark of Acacia holoserica is reported in a few publications as containing the B-phenethylamine alkaloid hordenine, up to 1.22% of the dry weight. Yet in a recent study of aboriginal medicinal plants all parts of this species were found to give a negative result for alkalo