Bioactive compounds of endophytic fungi from Lindenbergia philippensis Benth. and Leea rubra Blume ex Spreng

Abstract

The purpose of this research was to characterize bioactive compounds from endophytic fungi isolate LRUB20 from Leea rubra and isolate LPHIL36 from Lindenbergia philippensis. An organic extract from cultures of the isolate LRUB20 was purified by chromatographic techniques to afford four new pyrone derivatives, dothideopyrones A-D (1, 3, 4, and 5), along with seven known compounds, including cis,trans-muconic acid(9), questin (10), asterric acid (11), methyl asterrate (12), sulochrin (13), eugenitin(14), and 6-hydroxymethyleugenitin (15). The fermentation broth of the strain LPHIL36 afforded three new metabolites, corynesidones A (16) and B (18), and corynether A (20), together with a known diaryl ether (22). Their structures were elucidated by analysis of spectroscopic data. Dothideopyrone D(5) and its acetate derivative 6 exhibited moderate cytotoxic activity, while compounds 16, 18, 20, and 22 were relatively non-toxic against cancer cells, and inactive toward normal cell line. In addition, compound 16 inhibited aromatase activity with an IC50 value of 5.30 uM. On the basis of morphology and nucleotide sequences of ITS1-5.8S-ITS2 regions of rDNA, the fungus LPHIL36 was identified as Corynespora cassiicola. The LRUB20 isolate produced characteristic conidia. DNA sequences of its 18S. and ITS1-5.8S-ITS2 ribosomal RNA gene regions were found to be unique having no similar sequences in the GenBank. Based on both microscopic morphology and molecular data, this fungus was classified as mitosporic Dothideomycete LRUB20, a potentially new species.