Profiling of Bioactive Secondary Metabolites of Colletotrichum siamense Isolated from Catharanthus roseus with Emphasis on Moschamine by Advanced Chromatographic and Mass Spectrometric Techniques.

Endophytic fungi are microorganisms that live in symbiotic relationships with plants, residing within their tissues without causing damage or disease to the host. Endophytic fungi provide vitality to the host plant and are excellent producers of many secondary metabolites that may contain pharmaceutical properties. In this study, Catharanthus roseus (L.) G. was collected from various places in Jharkhand to identify and isolate the endophytic fungi found in the leaf tissues of these plants. A total of 30 unique fungal isolates were obtained and maintained through subculturing at regular intervals. Among them, Colletotrichum siamense was chosen for targeted indole alkaloid compounds and their chemical profiling due to its bioactive potential. Primary screening of the metabolites was done through alkaloid tests and HPTLC analysis. A comprehensive metabolite profiling of the selected isolate has been performed by employing advanced analytical techniques such as high-performance liquid chromatography, gas chromatography-tandem mass spectrometry, and liquid chromatography-high-resolution mass spectrometry. The data obtained through GC-MS showed many bioactive constituents present within the fungal extracts and included: chlorozotocin, indole, 2-Amino-3-(4-hydroxyphenyl)-propanoic acid, 7-Methyl-Z-tetradecen-1-ol acetate, digitoxin, and glucobrassicin. In addition, LC-HRMS confirmed the presence of indole alkaloids found in the extracts of C. siamense, including moschamine and many other secondary metabolites. HPLC-DAD further analysed the fungal extracts, with quantification of moschamine at 109.13 µg/mL. The current research identified endophytic fungi isolated from C. roseus that may serve as valuable sources of pharmacologically active compounds. The observation of unique metabolic patterns among the isolates indicates that a variety of biosynthetic pathways exist within the endophytic fungi, as exemplified by the discovery of moschamine from Colletotrichum siamense.