Profiling Secondary Metabolites of Cocoa (Theobroma cacao L.) Endophytic Fungi Lasiodiplodia pseudotheobromae PAK-7 and Lasiodiplodia theobromae TN-R-3 and Their Antimicrobial Activities

Aims: To determine the chemical composition of secondary metabolite of cocoa endophytic fungi L. pseudotheobromae PAK-7, L. theobromae TN-R-3 and their anti-oomycete activities.

Statistical Design: Multivariate analysis.

Place and Duration of Study: Department of Plant Pathology, TNAU, Coimbatore, Tamil Nadu from April 2018 to December 2019.

Methodology: Lipophilic extracellular secondary metabolites were extracted using ethyl acetate as a solvent and their chemical composition was detected by Gas Chromatography-Mass Spectrometry (GC-MS) and identified by NIST library and Pub Chem databases.

Results: Metabolic profiling of cocoa endophytic fungi L. pseudotheobromae PAK-7 and L. theobromae TN-R-3 showed the presence of eleven peaks representing nine compounds. The most abundant compound observed were Acetic acid, 3-methyl-6-oxo-9oxabicyclo[3.3.1]non-2-yl ester, 2H-Pyran-2-one, tetrahydro-4-hydroxy-6-pentyl-, Melezitose, Ethyl à-d-glucopyranoside collectively representing 58.01% area. In comparison to L. pseudotheobromae PAK-7 GC-MS analysis of L. theobromae TN-R-3 exhibited the presence of 29 peaks. The most abundant compounds were dl-Mevalonic acid lactone, Methyl 6-O-[1-methylpropyl]-á-d-galactopyranoside, 2H-Pyran-2-one, tetrahydro-4-hydroxy-6-pentyl-, Melezitose, Ethyl à-d-glucopyranoside, 1,6-Anhydro-á-d-talopyranose collectively representing 60.47% of the total area.

Conclusion: Chemical compositions and anti-oomycete activities of crude secondary metabolites of L. pseudotheobromae PAK-7, L. theobromae TN-R-3 differed entirely depending on the property and abundance of bioactive metabolites.