Phytochemical analysis and antimicrobial activity of Aparajita (Clitoria ternatea Linn.) against rice pathogens

Abstract
Clitoria ternatea Linn. commonly known as butterfly pea and Aparajita belongs to the family fabaceae. It was originated from tropical Asia and afterwards widely distributed to African countries. Generally it is grown as ornamental plant due to its attractive flower colour. In traditional ayurvedic medicine, it has been used for centuries as a memory enhancer, antistress, anxiolytic, antidepressant, anticonvulsant, tranquillizing and sedative agent. The tribal people of Tripura use leaf and root part of Aparajita against urinary tract infections due to its antimicrobial property. The present investigation was intended to study the phytochemical composition and antimicrobial activity of Clitoria ternatea Linn against rice pathogens. The plant materials were collected from Jagduar, Teok, Jorhat, Assam and Matabari, Gomati District, Tripura and authenticated. The morphological data were taken from the mature plant to narrate the botanical information. Leaf, stem and twig samples of this species were analyzed for total alkaloids, total phenolics and total terpenoid content by standard protocol. The antimicrobial activity of the methanolic plant extract has been tested against some rice pathogens by poison food technique and the natural food colorant from the flower of C. ternatea L extracted. From the results of the present investigation it was observed that the difference in plant morphological characteristics in the two samples was not significant and found statistically at par. The variation in moisture content on fresh weight basis between the two samples viz. Assam (S1) and Tripura (S2) of Clitoria ternatea L. was not significant. On the other hand, the highest moisture content on dry weight basis was found in flower of S1 collected from Assam which was 13.70% while the leaf recorded the lowest 8.82% of moisture. The total phenolics content recorded in the leaf were 1.524g/100g and 1.277g/100g, in stem 0.706g/100g and 0.682g/100g, and in twig 1.110g/100g and 1.209g/100g in S1 and S2 sample, respectively. The alkaloid content of the leaf was found to be 1.000g/100g and 0.875g/100g, in stem 0.753g/100g and 0.627g/100g, and in twig 1.627g/100g and 1.253g/100g in S1 and S2 sample, respectively. By the qualitative test it was observed that the terpenoid was absent in leaf, stem, and twig in the both Assam (S1) and Tripura (S2) sample but was present in flower of both the sample although the variation was not significant. The total terpenoid content of flower was found to be 0.698g/100g and 0.675g/100g in Assam (S1) and Tripura (S2) sample respectively. The antimicrobial activity of methanolic plant extracts of Clitoria ternatea L. was evaluated against Magnaporthe grisea, Drechslera oryzae, Rhizoctonia solani, Sarocladium oryzae and Fusarium sp. Although the methanolic plant extract of C. ternatea L could not inhibit the mycelia growth of Drechslera oryzae but the extract proved effective in inhibiting the growth of other remaining pathogens viz Magnaporthe grisea, Rhizoctonia solani, Sarocladium oryzae and Fusarium sp.. Highest inhibition of growth was recorded in Rhizoctonia solani. The natural food colorant has been extracted from Clitoria ternatea L. flower. Variation in color has been observed at different pH. The changes in pH were brought about by adding lemon juice and alkali extracted from vimkol. To immobilize the color on to edible inert carrier food material, glucose powder was effective in color immobilization. Further studies will be required for assessing mode of antimicrobial activity of the methanol extract on the plant pathogens, which will open an interesting area to manage various diseases in crop plants under organic cultivation. More studies will be required to find out the efficacy of the plant extract against other pests. The study further suggested that some of the plant extracts possess compounds with bioactivity properties that could be used as active principles or agents in new drugs for the therapy of infectious diseases. The food colour extracted from the flower of C. ternatea L. could be an ideal natural colorant for the food industry in future.
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