Endophytic fungi isolated from Morinda citrifolia L. leaves and twigs

Abstract

Endophytic fungi 178 isolates were isolated from leaves and twigs of Morinda citrifolia L. collected from 4 provinces of Thailand. Endophytic fungal isolate LSS06 cultured on malt extract agar had the best antimicrobial activity because it was the only isolate that inhibited the growth of tested gram positive bacteria (Bacillus subtilis and Staphylococcus aureus ), gram negative bacteria (Escherichia coli), and yeast (Candida albicans). Based on morphology and nucleotide sequencing analysis of ITS regions of rDNA, endophytic fungal isolate LSS06 was identified as Nodulisporium sp. Isolation of EtOAc extract crude of the culture broth of endophytic fungal isolate LSS06 cultivated in malt extract broth gave mixture B1 and mixture B2. Isolation of EtOAc extract crude of the mycelia gave mixture M1, mixture M2 and compound M1. The structure elucidation of these compounds was achieved by analysis of their spectroscopic data and physical properties. The structures of mixture B1 and mixture B2 were still unidentified. Mixture M1 was diglyceride which composed of 3 saturated fatty acids including myristic acid, palmitic acid, and stearic acid and 3 unsaturated fatty acids which were palmitoleic acid, oleic acid and linoleic acid. Mixture M2 was a mixture of saturated C[subscript 16]-C[subscript 18] long chain carboxylic acid. Compound M1 was identified as D-mannitol. From the biological activity testing of isolated compounds, mixture B1 inhibited growth of B. subtilis ATCC 6633 with the MIC value of 1000 microgram/ml but no cytotoxicity, while other compounds did not inhibited any tested microorganisms