Antifungal activity of pinosylvin from Pinus densiflora on turfgrass fungal diseases

The objective was to examine the antifungal activity of Pinus densiflora extract for the control of turfgrass fungal diseases. Antifungal activities of the various fractions of n-hexane, methylene chloride (Ch), ethyl acetate (EtOAc), and n-butanol from P. densiflora were evaluated against Rhizoctonia solani AG1-1B, R. solani AG2-2IV, Sclerotinia homoeocarpa, R. cerealis, Pythium spp., and Colletotrichum graminicola. The Ch and EtOAc fractions showed antifungal activity against Pythium sp. and C. graminicola in paper disc assay. The effective concentration to produce 50% mycelial inhibition (EC 50 ) using five discriminatory concentrations of pinosylvin (1) from the Ch fraction of P. densiflora was evaluated on R. solani AG1-1B, R. solani AG2- 2IV, R. cerealis, and S. homoeocarpa. S. homoeocarpa showed the highest sensitivity with the lowest mean EC50 value (8.426 μg/ mL) among the four pathogens. Among the three Rhizoctonia pathogens, R. cerealis had the highest mean EC50 value (99.832 μg/mL) and R. solani AG2-2IV, with the lowest sensitivity, had the lowest EC 50 value (39.696 μg/mL). These results suggested that pinosylvin (1) from P. densiflora could be a valuable lead compound in the improvement of a novel antifungal agent.