Secondary metabolites from Curvularia sp, an endophytic fungus isolated from the leaves of Picralima nitida durand and hook (Apocynaceae)

Abstract

Nature has remained a major source of pharmacologically active compounds used for the treatment of new and existing diseases, or as lead molecules for the development of synthetically derived analogues. This research was carried out to determine the secondary metabolites from the extract of Curvularia sp, an endophytic fungus associated with the leaves of Picralima nitida. The endophytic fungus was isolated and purified from the leaves of the plant material, using the conventional methods. The identity of the fungus was determined by molecular biology characterization. A combination of chromatographic methods (high performance liquid chromatography and column chromatography), spectroscopic techniques (1-D and 2-D nuclear magnetic resonance spectroscopy and mass spectrometry), dereplication and literature data comparison were used to isolate, purify and identify the secondary metabolites in the fermentation extract of the endophytic fungus. Three previously reported compounds, acropyrone (1), 4-hydroxyphenylacetic acid (2) and indole-3-acetic acid (3) were isolated for the first time from Curvularia Sp extract. Compounds 1-3 were tested for microbial and cytotoxic properties. The compounds showed no antimicrobial properties at 1 mg/mL, no observable cytotoxic properties at the dose of 10 µg/mL and no antimycobacterial properties at the dose tested. Although there was no significant bioactivity, the result further confirms the usefulness of endophytic fungi as a secondary metabolite factory for the production of drugs and drug precursors in the laboratory.