INTRODUCTION

INTRODUCTION

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Nature has been a source of medicinal agents for thousands of years and an impressive

number of modern drugs have been isolated from natural resources. Traditional medicine is

an important source of potentially useful active compounds for the development of

chemotherapeutic agents. Emergence of pathogenic microorganisms that are resistant/ multi

resistant to major classes of antibiotics have increased in recent years due to indiscriminate

use of synthetic antimicrobial drugs. In addition, high cost and adverse side effects are

commonly associated with popular synthetic antibiotics (such as hypersensitivity, allergic

reactions, immunosupression etc.) and are major burning global issues in treating infectious

diseases. Although pharmacological industries had produced considerable number of

commercial antibiotics time to time but resistance of pathogens towards these drugs too has

increased at high rate and multi drug resistant microorganisms have exacerbated the

situation. In the present scenario, there is an urgent and continuous need of exploration and

development of cheaper, effective new plant based drugs with better bioactive potentiality

and least side effects. Hence, recent attention has been paid to biologically active extracts

and compounds from plant species used in herbal medicines (Sharma B and Kumar P.,2008-

09).

Plants continue to be a major source of medicines, as they have been throughout human

history. It is estimated that roughly 1500 plants species in Ayurveda and 1200 plant species

in Siddha have been used for drug preparation. Nearly 80% of the world population rely on

traditional medicines for primary health care, most of which involve the use of plant extract

as traditional medicine. Plants are like natural laboratories where a great no. of chemicals are

synthesized and in fact they can be considered as the important sources of bioactive

phytochemicals.

Antimicrobials of plant origin have enormous therapeutic potentiality and have been used

since time immemorial. They have been proved effective in the treatment of infectious

diseases simultaneously mitigating many of the side effects which are often associated with

synthetic antibiotics (Iwu at al., 1999).

Different strategies have been employed for controlling phytopathogenic fungi and bacteria

including sanitation, use of pathogen free seeds and use of chemical fungicides and

bacteriocides. Usual practice in sustainable agriculture cause extreme toxic effects to

mankind as well as to the ecosystem. Moreover the measures are sometimes costly and the

pathogens during the later stages become resistant to the used chemicals. (Stall and Thayer,

1962, Jones and Jones.,1985, Stall et al., 1986, Sigee 1993) . Marco and Stall., 1983; Ritchie

and Dittapongitch, 1991; Pernezny et al., 1997 and Martini et al., 2004 reported the control

of bacterial spot of tomato with copper or copper plus EBDC (ethylene bis dithio carbamate)

where presence of copper causes production of copper resistance pathogen population. Wide

spread streptomycin resistance within pathogen population have been reported by Ritchie

and Dittapongitch in 1991. Pathovers of Xanthomonas causing disease on several cash crops

35

and vegetables have been reported to develop resistance to kanamycin, ampicilin, penicilin

and streptomycin by Verma et al. in 1989.

During the recent times, some workers have suggested the use of plant extracts which were

reported as effective inhibitors of phytopathogenic microbial growth. Xanthomonas

campestris was reported to be suppressed by Tamarindus indica L. plant extract (Garden et

al.1978,Grainge et al.1987, Leksomboon et al.1998, Leksomboon et al.2000). Leksomboon

et al .2001 reported inhibitory effects of aqueous extract of Hibiscus subdariffa, Psidium

guajava, Punica granatum, Spondias pinnata and Tamarindus indica against Xanthomonas

campestris pv. citri by reducing canker incidence of citrus. Gislene et al. (2000) showed

antibacterial activity of several plant extracts against several antibiotic resistant bacteria.

Lourencoamorim et al. in 2004 showed fungitoxic activity of the hexane and methanol

extracts of leaves of Copaifera langsdorffi against two phytopathogenic fungi

Colletotrichum gloeosporioids and Bipolaris sorkiniana. Kumudini et al in 2005 reported

phytotoxin and antifungal compounds from two Apiaceae species, Lomatium californicum

and Ligusticum hultenii , rich source of z-ligustilide and apiol respectively. Sharma and

Kumar (2009) reported the free and bound flavonoids from different parts of Tridax

procumbens L. (Asteraceae) and Capparis decidua Forsk (Edgew) (Capparaceae) and

studied their antimicrobial activities using disc diffusion assay against two Gram negative

bacteria (Escherichia coli MTCC 46 and Proteus mirabilis MTCC 425), one Gram positive

bacteria (Staphylococcus aureus MTCC 87), and a fungi (Candida albicans MTCC 183).

The leaf extract of Artemisia nilagirica was screened for antibacterial activity against some

clinical and phytopathogenic bacteria like Pseudomonas aeruginosa, Yersinia enterocolitica,

Preteus vulgaris, Enterobactor aerogenes, Salmonella typhi, Escherichia coli, Bacillus

subtilis, Shigella flaxneri (Ahameethunisa et al. 2010).

Clitoria ternatea L., commonly known as Butterfly pea belonging to the family Fabaceae

and sub-family Papilionaceae is a perennial leguminous twinner, originated from tropical

Asia and later was distributed widely in South and Central America, East and West Indies,

China and India, where it has become naturalised. It is also commonly called as Clitoria,

blue-pea, Mazerion, (www.neoherbal.com) kordofan pea (Sudan), cunha (Brazil) or

pokindong (Philippines), Shankhpushpi. It has several Sanskrit names: Aparajita, Girikarnu,

Asphota and Vishnukranta. It is a vigorous, summer growing, legume of old world origin.

Clitoria L. comprises 60 species distributed mostly within the tropical belt with a few

species found in temperate areas. The most frequently reported species is Clitoria ternatea.

From ancient times “Shankhpushpi” is known as reputed drug of Ayurveda and reported as a

brain tonic, nervine tonic and laxative. It is considered as a MEDHYA-RASAYANA in

Ayurvedic texts. It is an Ayurvedic drug used for its action on the CNS, especially for

boosting memory and improving intellect. The flowers of the plant Clitoria ternatea

resemble a conch shell; therefore it is commonly called “SHANKPUSHPI” in the Sanskrit

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language where it is reported to be a good “MEDHYA” (brain tonic) drug and, therefore,

used in the treatment of “Masasika Roga” (mental illness) ( Sethya et al.,2009). Extracts of

this plant have been used as an ingredient in MEDHYA-RASAYANA, are juvenating recipe

used for treatment of neurological disorders (Kumar et al., 2008).

Fantz (1977) reported economic uses for 23 species of Clitoria as antihelmintic, diuretic,

refrigerant etc. The plant is mainly used as a forage as it is highly palatable for live-stock

and it is well adapted to various climates. It is also used as drought resistant pasture in arid

and semi arid regions (Kirtikar and Basu,1935; Anonymous, 1950; Manandhar, 2002). C.

ternatea is known as a very bioactive plant and used in various diseases as folk medicine.

The roots are being used in diuretic, leucoderma, leprosy, hemicranias, amentia, pulmonary

tuberculosis, bronchitis, purgative, ophthalmology and reported as cathartic aphrodisiac

tonic (Nadkarni et al. 1976) and seeds as cathartic. In the traditional system of medicine

particularly in Ayurveda, the roots, seeds and leaves of C. ternatea L. have long been widely

used as a brain tonic and is believed to promote memory and intelligence (Rai et al., 2002;

Mukherjee et al., 2007c) . Use of C. ternatea root powder to treat indigestion, eye diseases

and headache are well accepted. It is used as a purgative and to reduce fever. Infusion of

leaves is used for eruptions. Root juice applied in migraine. Overall it is a traditional

Ayurveda medicine used as a brain tonic, memory and intelligence enhancer, anti-depressant

(Steru et al.,1985), anti stress (Alpine et al.,1969), anxiolytic, sedative (Jain et al.2003) and

anti-convulsant, analgesic (Parimaladevi et al., 2004 , 2003). leaves are used in headache

and swelling of adjacent glands. Juice is used as an anti-dote against snake–bite. Leaves are

used as poultices for swollen joints. Seeds are used as mildly laxative, purgative and

antihelmintic ( Khadatkar et al.,2008, Nirmal et al.,2008). Paste of flowers is applied to cure

infections of eye and for headache. Entire plant is used as antidote for snake-bites. C.

ternatea L. petals have been recognized to possess anti-oxidant (Kamkaen et al.) activity.

The major phytoconstituents found in the plant are the pentacyclic triterpenoids such as

taraxerol and taraxerone. Anti-viral activity was evaluated and Clitoria ternatea extract

exhibited most potent activity and this provides more support for the concept of scientific

validation of traditional plant medicines in the fight against infectious diseases. C. ternatea

is used to cure various diseases like hyperglycemia (Daisy et al.,2009) constipation, UTI,

inhalation, asthma, throat, eye infections, skin diseases. facial care, jaundice, boosting

memory and intelligence, anti-depressant , anxiolytic, sedative and anti-convulsant ( Jain et

al.,2003,Swunyard et al.,1982), demulcent, anticancerous (Balachandran et al.,2005),

urinogenital disorders, disease of liver, spleen and rheumatic affections (Kapoor 2005).

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Systematic position of Clitoria ternatea L.:

Group : Dicotyledons Polypetalae

Series : Caliciflorae

Order : Rosales

Family : Leguminosae

Subfamily : Papilionoideae

Genus : Clitoria

Species : ternatea

Presumably of African origin, today it is cultivated and naturalized throughout the humid

tropics of the old and new world below 1600 m elevation (Morton, 1981). It is distributed in

India, the Philipines, other tropical Asian countries, South and Central America, the

Caribbean and Madagascar (Anonymous ,1988: Sivaranjan and Balachandran, 1994). The

species ranges from Florida to Texas, and from New Jersey to Kentucky, Arkansas. It is

widely distributed in Mexico, The Bahamas, Cuba, Dominican Republic, Haiti, Jamaica,

Puerto Rico, Turks and Caicos Islands, South America to Paraguay and Argentina (Austin

2004).

It is an ornamental perennial climber, up to 2-3 m in height, growing wild and also in

gardens bearing conspicuous blue or white flowers resembling a conch-shell. Leaves are

pinnately compound 6-13 cm long, leaflet ovate to oblong 2-5 cm long, flowers axillary,

Fig. I.1: Morphological variations of flowers of C. ternatea L. species:

A= C. ternatea L.

Blue variety,

B= C. ternatea L.

Plant in Natural Habitat

C= C. ternatea L.

white variety, D= Violet colour

variety, E=C.

ternatea L. Blue variety

F= C. ternatea L.

white variety

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Fig. I.2: Morphological variations of flowers of C. ternatea L. species:

solitary, pedicel 8-13 mm long papilionaceous white or bright blue with yellow or orange

centre. Calyx 1.3-2.0 cm, corolla 3.8-5 cm, pods 5-10 cm by 8-13 mm, flattened, nearly

straight, sharply beaked sparsely hairy (Karandikar and Satakopan,1959, Pillai,1976). Seeds

6-10 yellowish brown in colour. Though a hardy perennial, the climber is grown in gardens.

The white and blue flowered types cross naturally resulting variety of colours and single and

double forms. Its roots fix nitrogen; therefore the plant has been used to improve soil

quality. There are two varieties of Clitoria, blue flower and white flower varieties.

Transverse section of the root shows presence of cork .cork cells are isodiametric and show

presence of lignin. Phelloderm is present below the cork layer, composed of 12-16 rows of

parenchyma. Medullary rays are 2-4 seriate containing starch grains that are oval in shape

with 3-4 um in diameter. Phloem parenchyma contains calcium oxalate crystals (Mukherjee

et al.,2008, Kalamani and Michael,2001). Phelloderm parenchyma also contains starch

grains. Xylem contains many lignified vessels (Dnyaneshwar et al.2010).

Primary and secondary metabolites of the plant:

1. From Roots: The roots form nodules, which contain higher amount of plant growth

substance such as indole acetic acid, kinetin and gibberelic acid. The level of tryptophan,

precursor of indole acetic acid was also higher in the nodules. Rhizobium spp. isolated from

root nodules produced higher amount of indole acetic acid in culture when supplemented

G= C. ternatea L.

violet, multi petal

variety, H= C.ternatea

L.blue, multi petal

variety I= C. ternatea L.

pink variety,

J= pink colour variety, K=C.

ternatea L. white

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with tryptophan (Ahmad et al.,1984). Rajagopalan (1964) investigated the presence of free

amino acids and amides in the root nodules of C. ternatea; the root nodules contains glycine,

alanine, valine, leucine, -aminobutyric acid, aminobutyric acid, aspartic acid, glutamic acid,

methyleneglutamic acid, arginine, ornithine, and histidine and -aminobutyric acid. Banerjee

and Chakravarti (1963, 1964) reported the isolation and identification of pentacyclic

triterpenoids, taraxerol and taraxerone from the roots (Banerjee and Chakravarti, 1963,

1964). Content of Taraxerol (1) in root of C. ternatea was determined through high

performance thin layer chromatography (HPTLC) by Kumar et al. (2008). Yadava and

Verma (2003) isolated antimicrobial flavonol glycoside 3,5,4-trihydroxy-7-

methoxyflavonol-3-O--d-xylopyranosyl-(1,3)-O--d-galacto pyranosyl (1,6)-O--d-

lucopyranoside from the ethyl acetate soluble fraction of the defatted seeds of C. ternatea.

Fig. I.3: Structures of few compounds isolated from C. ternatea L.

Poly hydroxy cinnamic acid Taraxerone Taraxerol

Phytochemical screening of the roots shows the presence of ternatins, alkaloids, flavonoids,

saponins, tannins, carbohydrates, proteins, resins, starch, taraxerol and taraxerone. A wide

range of secondary metabolites including triterpenoids, flavonol glycosides, anthocyanins

and steroids has been isolated from Clitoria ternatea Linn. Four kaempferol glycosides I II,

III and IV were isolated from the leaves of Clitoria ternatea L. Kaempferol-3- glucoside (I),

kaempferol-3 -rutinoside (II) and kaempferol-3-neohesperidoside (III) were identified by

Ultra Violet, Protein Magnetic Resonance and Mass Spectrometry. (IV), C33H40O19, mp:

198, was characterized as Kaempferol-3-orhamnosyl and was named as clitorin (Morita et

al., 1977).

2. From Seeds: These contain a protein with amino acid sequences similar to that of insulin

but with the absence of histidine, threonine, proline and cystine. The seeds yield a greenish-

yellow fixed oil (Joshi et al.,1981, Tiwari and Gupta, 1957). The fatty acid content of C.

ternatea L. includes palmitic, stearic, oleic, linoleic, and linolenic acids (Vianni and

Souto,1971; Debnath et al.,1975; Joshi et al.,1981; Husain and Devi,1998). The seeds also

contain a water-soluble mucilage, delphinidin 3,3,5-triglucoside, useful as a food dye,

besides, three unidentified trypsin inhibitors (Macedo and Xavier.,1992). Other substances

present in the seeds are p-hydroxy cinnamic acid,flavonol-3-glycoside, ethyl--d-

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galactopyranoside, adenosine,3,5,7, 4 tetra hydroxyl flavone, 3-rhamnoglucoside,a

polypeptide, hexacosanol-sitosterol, sitosterol and an anthoxanthin glucoside (Sinha,1960;

Kulshrestha and Khare,1967,1968; Gupta and Lal, 1968). The seeds also contain

oligosaccharides or flutulene (Revilleza et al., 1990). Kelemu et al. (2004) isolated

antimicrobial and insecticidal protein finotin from seeds of C. ternatea L. The seeds contain

nucleoprotein with its amino-acid sequence similar to insulin, delphinidin-3,3,5-triglucoside,

essential amino-acids, pentosan, watersoluble mucilage, adenosine, an anthoxanthin

glucoside, greenish yellow fixed oil (Joshi et al,1981,Tiwari and Gupta,1957), a phenol

glycoside, 3,5,7,4-tetrahydroxy-flavone-3-rhamoglycoside, an alkaloid , ethyl D-galacto

pyranoside, p-hydroxycinnamic acid polypeptide, a highly basic protein-finotin, a bitter acid

resin, tannic acid, 6% ash and a toxic alkaloid (The Wealth of India, Publication and

Information Directorate, Vol II, Council of Scientific and Industrial Research, New Delhi,

2005, 71-73, Potsangbam et al. 2008). According to Yoganarasimhan (2000) seeds contain ᵞ-

sitosterol, ß-sitosterol, and hexacosanol and anthocyanin glucoside. (Yoganarasimhan SN,

2000; Sinha A,1960). It also contains anti-fungal proteins and has been shown to be

homologous to plant defensins (Osborn et al.,1995). It wa reported that a lectin present in

the seeds of Clitoria ternatea agglutinated trypsin-treated human B erythrocytes (Naeem et

al.2007). Since the purified lectin was found to be potential tool for cancer studies so an

attempt was made for the alternate high yielding purification method for Clitoria ternatea L.

lectin designated CTL, present in the seeds of this member of leguminosae family (Naeem et

al., 2007).

3. From Flowers: They have a vivid blue or white color and are of relatively large size, so it

is used as an ornamental around the world. In Southeast Asia, the blue flower pigment is

traditionally utilized as food colorant because of the high stability. Ternatins are blue

anthocyanins found in the petals of C.ternatea (Srivastava and Pande, 1977). They are

acylated anthocyanins based on delphinidin. The six major anthocyanins ternatins A1, A2,

B1, B2, D1, and D2, were isolated, and these structures were characterized as malonylated

delphinidin 3, 3, 5 triglucosides having 35 side chains with alternative d-glucose and p-

coumaric acid units (Terahara et al., 1989, 1990, Kondo et al., 1990). Terahara et al. (1996)

reported the isolation and characterization of five ternatins A3, B4, B3, B2, and D2 from CT

flowers, and the structures were determined by spectroscopic methods using a combination

of chemical analysis such as FABMS, 1H and 13C NMR spectroscopies as delphinidin 3-

malonyl G having 3GCG-5GCG, 3GCG-5GC, 3GCGCG-5GC, 3GCGC-5GCG, and

3GCGC-5C side chains, respectively, in which G is d-glucose and C is p-coumaric acid.

Terahara et al. (1998) isolated eight anthocyanins ternatins. C1, C2, C3, C4, C5, D3,

preternatins A3 and C4. The structures of ternatins C1, C2, C3, C4, C5, and D3 1–6 were

postulated as delphinidin 3-malonylglucoside having 3-GCGC-5-G, 3-GCGCG-5-G, 3GC-

5G, 3-GCG-5-G, 3-G-5-G, and 3-GC-5-GC, and compounds preternatins A3 and C4 as

delphinidin 3-glucosidehaving 3-GCG-5GCG and 3-GCG-5-G as side chains, respectively.

Ranaganayaki and Singh (1979) reported kaempferol isolation and identification from the

flowers of C. ternatea. Saito et al. (1985) detected kaempferol, kaempferol 3-2G-

rhamnosylrutinoside, kaempferol 3-neohesperidoside, kaempferol 3-rutinoside, kaempferol

3- glucoside, quercetin, quercetin 3-2G-rhamnosylrutinoside,quercetin 3-neohesperidoside,

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Quercetin 3-rutinoside, quercetin 3-glucoside, Myricetin 3-neohesperidoside (Kazuma et al.,

2003), Myricetin 3-rutinoside and Myricetin 3-glucoside. Three flavanol glycosides,

kaempferol3-O-(2-O--rhamnosyl-6-O-malonyl)--glucoside, quercetin3-O-(2-O--rhamnosyl-

6-O-malonylglucoside and myricetin 3-O-(26di-O--rhamnosylglucoside were isolated from

the petals of C. ternatea L. together with eleven known flavanol glycosides (Kazuma et al.,

2003a, 2004). Kazuma et al. (2003) investigated the flavonoids in the petals of several C.

ternatea L., with different petal colors using LCMS/MS. Delphinidin 3- O-(2O--rhamnosyl-

6O-malonyl)--glucoside, delphinidin3-O-(6O-malonyl)--glucoside, delphinidin 3-

neohesperidoside and delphinidin 3-Oglucoside were isolated from the petals together with

three known anthocyanins. All through ternatins, a group of 15 (poly) acylated delphinidin

glucosides were identified in all the blue petal lines. Another study demonstrated that minor

delphinidin glycosides, eight anthocyanins (ternatins C1, C2, C3, C4, C5 and D3 and

preternatins A3 and C4) were isolated from the young Clitoria ternatea flowers (Terahara

N., 1998). Recent study showed that malonylated flavonol glycosides were isolated from the

petals of C.ternatea L. with different petal colors using LC/MS/MS (Kazuma et al. 2003). It

was also reported that five new anthocyanins, ternatins A3, B3, B4, B2 and D2 were isolated

from C.ternatea flowers (Terahara N, 1996). Ranaganayaki and Singh (1979) reported

kaempferol and Saito et al. (1985) detected kaempferol-3-glucoside, kaempferol-3-

robinobioside-7-rhamnoside, quercetin and quercetin 3-glucoside (Kazuma et al. 2003;

Terahara N., 1996; Ranaganayaki and Singh, 1979; Saito et al., 1985). Six ternatins A1, A2,

B1, B2, D1 and D2 in Clitoria ternatea flowers were isolated by reversed phase High

Performance Liquid Chromatography and their structures were partly characterized as highly

acylated delphinidin derivatives (Terahara et. al. 1990). C. ternatea was powdered and

evaluated quantitatively for the analysis of total soluble sugars, protein, phenol, starch,

carbohydrate and lipid (Shekhawat N, Vijayvergia R, 2010)

4. From Leaves: These contain sitosterol, kaempferol -3- monoglucoside, kaempferol -3-

rutinoside, kaempferol-3-neohesperiodoside, kaempferol-3-O-rhamnosyl-(1,6)-glucoside,

kaempferol-3-O-rhamnosyl - (1,6) - galactoside and kaempferol - 3 – O – rhamlnosyl- (1,2)-

Ochalmnosyl-(1,2)-O- [rhamnosyl-(1,6)] -glucoside. Lactones aparajitin and clitorin from

leaves were also reported (Tiwari and Gupta, 1959; Morita et al., 1977; Ripperger, 1978).

The leaves also contain an essential oil, colouring-matter and mucilage. The mucilage

contains anhydrogalacatan, anhydropentosan and methylpentosan and an alkaloid (Sinha,

1960c). The structures of the major constituents of C. ternatea L. (Mukherjee et al.,2008).

42

Fig. I.4: Structures of few compounds isolated from C. ternatea L.

,

Fig. I.5: Secondary metabolites isolated from C. ternatea L.

Structures of anthocyanin Delphinidin 3-malonyl glucoside

�-sitosterol Delpninidin

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Anti-microbial activities of C. ternatea L.:

The methanolic extracts of the leaves and root of C. ternatea L. were tested for their

antibacterial activity against different pathogenic drug resistant Gram-positive and Gram-

negative clinical isolates. The leaf was found to possess powerful antibacterial activity

against E. coli and V. cholera and S. aureus, quercetin may be the responsible compound

(Mazumder et al., 2007). Crude extract from seeds of Clitoria ternatea showed maximum

zone of inhibition against E. coli and M. flavus and the callus extract showed maximum

zones of inhibition against S. typhi while the lowest with E. coli and S. aureus (Mhaskar et

al., 2010). Alcoholic and Aqueous extracts from in vitro raised calli was active against

Salmonella spp. and Shigella dysenteriae; organisms causing enteric fever (Shahid et

al.,2009). In addition, the methanol crude extracts showed anti-bacterial activity against K.

pneumonia and The crude extract from seeds of C. ternatea L. showed strong antifungal

activity on the K. pneumonia and P. aeruginosa (Shekawat and Vijayvergia, 2010) and

fungus A. niger and A. ochraceous followed by other organisms (Mhaskar et al., 2010).

The presence of small molecular weight, cystein rich protein, finotin obtained from seeds of

the plant C. ternatea has been demonstrated for its antifungal property (Kelemu et al., 2004).

against selected fungi (Aspergillus niger) (Kamilla et al.,2009). The extract showed a

favourable antifungal activity (Jagbir Chahal et al., 2010). The crude extract from the seed

exhibited strong antifungal activity against Rhizoctonia solani, Zabrotes subfasciatus and

Acanthosceldius obtectus (Kelemu et al., 2004).

From the above discussion, it is evident that Clitoria ternatea L. is a rich source of chemical

compounds of a large variety and is widely accepted and used in various medicinal and

pharmacological field. Many of the compounds were found to be active against a wide range

of bacterial population, hence is used as antibacterial agents to cure bacterial diseases. But

there are very few reports available regarding the plants activity as antifungal agents against

plant pathogens. The present study was taken up to find out whether such therapeutically

important plant possesses antifungal properties against other few plant pathogens.

As far literature survey reveals, legumes are highly economically important plants especially

for their protein content. Among various types of legumes, most important pulses of India

are Black gram (urd), green gram (moong), chick pea (tur) and cheak pea. Fungal infestation

of such pulse crop is a serious threat in term of final yield. The pulses are susceptible to

fungal pathogens in a no. of deleterious ways disturbing the biochemical and metabolic

status of the plant. Among the biochemical disturbances, the most common effect is

alteration of enzymatic activity, as for eg. alteration of peroxidase activity (Lagrimini et

al.1987, Kerby et al.,1989), Accumulation of phytoalexins and production of pathogenesis

related proteins (Sequeira,1983) that reduce yield of seeds, hamper both quality and

quantity of the healthy seeds. Decreased germination capacity and mycotoxin production

also happens (Castillo et al. 2002, Quenton et al., 2003). Generally it has been found that

legumes are prone to fungi eg. Alternaria, Fusarium, Penicillium, Mucor, Aspergillus,

Rhizopus. The methods for controlling these phytopathogens are all toxic and hazardous for

the ecosystem. The application of various chemical compounds to control the diseases lead

44

to the accumulation of the chemical compounds in the soil, contaminate water even effects

the atmosphere which finally leads to ozone layer depletion. Considering such hazardous

effects of chemical applications, the biological controls techniques an ecofriendly measures

are suitable and gaining more and more importance nowadays.

As mentioned earlier, the pulses are more susceptible to fungal attacks and among them

Fusarium is one of the most important and harmful pathogen. Almost all types of legumes

are infected or infested by various strains of the fungus. Fusarium causes wilt in a wide

range of crop plants among which wilt of pigeon pea is the most important one. It is a world

wide spread disease causing up to 10% of total loss of crop only in India (Singh and Dahiya,

1973). The fungi is a member of the group Deuteromycetes, a soil borne fungi and

reproduces through macro and micro conidia which are perenating structures and remain

viable in the soil for a long time. Fusarium causes non specific host infestation and damage

to the pea plant, another most economically important legume crop. It is very difficult to

restrict the disease, once it appears. As it is a symptomless disease, in the early stages it

cannot be detected unless the lower leaves turns dry. Fruit is set but no. of pods and no. of

seeds per pod are decreased leading to a decrease in the yield of the plant, pod and quantity

and quality of the seeds and finally in total production of the crop.

Some measures have to be taken to control the disease in an ecofriendly manner. Due to the

increasing prevalence of multidrug resistant strains of bacteria and fungi, the recent

appearance of strains with reduced susceptibility to antibiotics raises the specter of

untreatable microbial infections and adds urgency to the search for new infection-fighting

strategy (Sieradski et al. 1999). Contrary to the synthetic drugs, antimicrobials of plant

origin are not associated with many side effects and have an enormous therapeutic potential

to heal many infectious diseases (Iwu et al., 1999). Unfortunately such green chemicals,

used as fungicides, are not too many. As discussed earlier, Clitoria ternatea L. contains a

wide range of chemical compounds, many of them possesses antifungal and antibacterial

properties. Keeping in mind, this work tried to find out whether C. ternatea L. is active

against Fusarium oxysporum ciceri.

To incorporate such an ecofriendly approach in the present thesis, the author designed the

work in two segments – the first segment includes the screening of bioactive potentiality of

the plant C. ternatea L. followed by characterization of the active principle chemically.

Since the plant showed the presence of antimicrobial compounds, some practical field

application has been incorporated to control the Fusarium infestation in pea seeds and plants

with the isolated bioactive compound in the second segment.