Abstract:
The objective of this research is to examine the endophytic fungi biodiversity in Dipterocarp forest at Viengsa district Nan province, Thailand.This is the first report about biodiversity of endophytic fungi for this area. We also tested for antimicrobial activity against reference microorganisms such as Staphylococcus aureus, Bacillus subtilis, Pseudomonas aerogenosa, Escherichia coli and Candida albicans by paper disk susceptibility test, and anticancer activity against reference human cancer cell line including breast (BT 474), hepatoma (HEP-G2), gastric (KATO III), lung (CHAGO) and colon (SW620) by MTT assay. Eighteen fungi morphotaxa were selected and characterized from 302 cultures, which were isolated from 400 samples. The colonization frequency of endophytic fungi in wet season are higher than dry season. Species of Phyllosticta sp.1 (60 isolates), Phomopsis sp.1 (54 isolates) and Xylaria sp.1 (44 isolates) were the most frequently found. Endophytic fungi from different groups mainly belonged to coelomycetes, followed by ascomycetes and hyphomycetes respectively. The crude extract of endophytic fungi showed antimicrobial activity against tested microorganisms. They inhibited Gram positive bacteria more than Gram negative bacteria. The crude extract of endophytic fungi strain DTD 6 and FID 15 which were isolated from Dipetrocarpus tuberculatus Roxb. and Flacourtia indica Merr. inhibited specifically on gastric cancer cell line (KATO III). The ethyl acetate extract of 2 cultures broth were isolated by extraction, chromatographic technique and crystallization to give 2 compounds. On basic of physical properties and spectroscopic data, they were elucidated as 4-ethylmethoxybenzene and cytochalasin D. cytochalasin D showed activities against SW620, KATO III and Hep- G2 with IC₅₀ value of 4.66, 5.84 and 4.79 µg/ml, respectively.