Metabolomics studies of endophytic metabolites from Malaysian mangrove plant in the search for new potential antibiotics
Currently, endophytic fungi have been explored not just for their ecological functions but for their secondary metabolites as a new source of these pharmacologically active natural products. Accordingly, many structurally unique and biologically active compounds have been obtained from the cultures of endophytic fungi. The fungal strains Aspergillus aculeatus and Lasiodiplodia theobromae were isolated from the stem of the mangrove plant Avicennia lanata collected from the East coast of Peninsular Malaysia in Terengganu Province, Malaysia. The fungi were taxonomically identified according to their morphological characteristics as well as by DNA amplification and sequencing of the ITS region. Prior to this study, metabolomics has been applied to identify and optimize the production of bioactive secondary metabolites in both fungi at different growth stages and culture media. Metabolomic studies were afforded by both high resolution mass spectrometry and NMR spectroscopy. Metabolomic profiling data was processed by utilizing the quantitative expression analysis software Mzmine 2.10 coupled with the Antimarin database for dereplication studies. SIMCA P+ 13.0 was used to prove that the optimization models were statistically sound. Respective fungi were then later scaled up either in rice-solid and liquid culture media. Crude extracts were fractionated using several high-throughput chromatographic techniques and subjected to bioactivity-guided isolation work for anti-trypanosomal active metabolomes. Structure elucidation of isolated secondary metabolites was achieved using 2D-NMR and HRESI-MS.