Introduction: In an on-going research, the endophyte Aspergillus sp. HAB10R12 have been selected for detailed chemical investigation after its crude ethyl acetate extract showed promising anticancer properties with high selectivity. Methods: The former was determined on two cancer cell lines namely, HCT116 and MCF-7 (IC50 = 0.05 and 0.04 μg/mL, respectively) and one non-tumor cell line HeLa (IC50 = 10.5 μg/mL). Results: The result indicates the secondary metabolites produced by the fungus are 200 folds more selective towards cancer cells over normal cells, calling for an immediate detailed investigation of their composition. Preliminary chemical analysis of the crude extract using LC-MS, NMR and UHPLC-UV showed the presence of an uncommon group of diterpene pyrones (NF00659 A1, B1 and A3), previously isolated once with only partial characterization reported. Consequently, large scale isolation of secondary metabolites was carried out and led to the identification of four of the previously isolated diterpene pyrones. Conclusion: The isolation, characterization, relative stereochemistry analysis, and a plausible biosynthesis of the diterpene pyrone compounds is presented herein.
Centella asiatica or known as ‘pegaga’ in Malaysia, is a popular medicinal herb, which is being used as main ingredient or incorporated into various herbal products. Apart from efficacy, the chemical profile and potential toxic effect of the plant are two important aspects of concern towards ensuring product satisfaction and safety of consumers. This paper reports the qualitative and quantitative chemical analysis of the leaf ethanolic extract of C. asiatica using LCMS/MS. The acute toxiciy effect of the extract and selected marker chemical constituents were further analysed using a zebrafish model. Twenty constituents, were identified and the main chemical marker constituents of the plant viz asiaticoside, asiatic acid, and madecassic acid were further quantified. Asiaticoside was found to be present in higher concentration than the other marker constituents. Meanwhile in the acute toxicity test, the LD50 of the extract on the zebrafish model was determined to be 1250 mg/L while 100% mortality was observed at the highest test concentration of 2500 mg/L. However, acute toxicity evaluation on four marker triterpenoids of the herb, i.e asiatic acid, madecassic acid, asiaticoside and madecassoside, indicated them to be quite safe on the zebrafish model, with no mortality shown for test concentrations between 10 to 500 mg/kg BW.