Isolation and identification of endophytic fungi from Dendrobium huoshanense with their antibacterial and anti-inflammatory activities.

To examine the symbiotic relationship between Dendrobium huoshanense and its endophytic fungi, a total of 168 endophytic fungi were isolated and classified into 18 genera and 36 species via using pure culture and techniques of molecular biology. Among them, Stagonosporopsis oculihominis, Alternaria eichhorniae, Phyllosticta aristolochiicola, Aspergillus flavus and Fusarium lactis were the dominant genera. Further, the secondary metabolites produced by the dominant genera were screened for antibacterial and anti-inflammatory activities. The secondary metabolites of Stagonosporopsis oculihominis showed good inhibitory activity against Staphylococcus aureus and the release of nitric oxide (NO). Three benzene ring derivatives were also identified using chromatographic and spectroscopic techniques, including (Z)-1- hydroxy-4-(2-nitroethenyl)-benzene (1), p-hydroxybenzaldehyde (2) and p-hydroxyphenylacetic acid (3). These findings indicated that the endophytic fungi of Dendrobium huoshanense are diverse and their dominant genera exert similar anti-inflammatory and antibacterial effects as those of the host plant, which provided a scientific basis for the subsequent investigation of the medicinal value of Dendrobium huoshanense.