Isolation of bioactive compounds from endophytic fungi of medicinal plants

Abstract

Medicinal plants are the natural and known source of number of therapeutic molecules. Endophytic fungi colonizing the medicinal plants are of great focus of research as they have a potential to produce biologically active compounds that have the antimicrobial, antioxidant, cytotoxic and immunomodulatory properties. In this study two medicinal plants Terminalia arjuna (arjuna) and Tinospora cordifolia (Giloy) have been used for the isolation of the endophytic fungi. The total of 21 fungal isolates were obtained from T.arjuna (arjuna) and T. cordifolia (Giloy), fourteen from T. arjunaand seven from T. cordifolia. The crude extracts obtained from these isolates weretested for preliminary antimicrobial activity by agar disc diffusion method and MTT assay using test cultures. The maximum inhibition was shown by fungal extract AL2 amongst all the extracts ofT. arjuna. It showed inhibitory activity of 71% against P. aeruginosa, 82.23% against B. megaterium and75% against E.coli. Amongst the extracts from T. cordifolia fungal crude extract GS4 showed the prominent activity of 28%, 60% and 59% against E.coli, P. aeruginosa, and B. megaterium respectively. These extracts were also tested for their potential to scavenge free radicals. GS4 showed maximum radical scavenging activity of 75.65% at 250 μg/ml followed by AL2 which showed maximum radical scavenging activity of 64.34 at 500 μg/ml of concentration. Extract AL2 showed the presence of alkaloids and triterpenoids and crude extract GS4 indicated the presence of phenols, carbohydrates, alkaloid and steroids in phytochemical analysis. AL2 gave positive results for the lipase, protease and laccase enzyme activity tests whereas GS4 showed positive test for lipase and protease.On the basis of morphological and molecular studies endophytic fungi (AL2) isolate was identified as Alternaria spp.Preliminary TLC analysis was done and for fractionation column chromatography was performed. After column chromatography seven fractions were obtained andthese were subjected to antibacterial assay. The fractions 4 and 7 showed maximum bioactivityand hence,further characterized. Fraction 7 was analyzed using UV spectroscopic, HPLC, FTIR and LCMS analyses. The data obtained by analysis indicated the presence of taxol. Results obtained were compared with standard taxol.Endophytic fungi isolated from medicinal plants could be a vital source for obtaining novel and potent molecules targeted against various life threatening diseases.