Cytotoxic and antibacterial naphthoquinones from an endophytic fungus, sp.

OBJECTIVE

Endophytes have the potential to synthesize various bioactive secondary metabolites. The aim of the study was to find new cytotoxic and antibacterial metabolites from endophytic fungus, sp. isolated from the leaves of (L.) Benth. ex Kurz. (Fam: Apocyanaceae).

MATERIALS AND METHODS

The endophytic fungus was grown on potato dextrose agar medium and extracted using ethyl acetate. Secondary metabolites were isolated by chromatographic separation and re-crystallization, and structures were confirmed by H NMR, C NMR and mass spectroscopic data. The cytotoxicity was determined by WST-1 assay and brine shrimp lethality bioassay, while antibacterial activity was assessed by disc diffusion method.

RESULTS

Two naphthoquinones, namely anhydrofusarubin () and methyl ether of fusarubin (2), were isolated from sp. The isolated compounds and by WST-1 assay against human leukemia cells (K-562) showed potential cytotoxicity with IC values of 3.97 μg/mL and 3.58 μg/mL, respectively. Initial screening of crude ethyl acetate extract and column fractions F-8 and F-10 exhibited noticeable cytotoxicity to brine shimp nauplii with LC values of 42.8, 1.2 and 2.1 μg/mL, respectively. Moreover, the isolated compound 2 (40 μg/disc) showed prominent activities against , , and with an average zone of inhibition of 27 mm, 25 mm, 24 mm and 22 mm, respectively and the activities were compared with kanamycin (30 μg/disc).

CONCLUSION

Our findings indicate that anhydrofusarubin () and methyl ether of fusarubin () might be useful lead compounds to develop potential cytotoxic and antimicrobial drugs.