Inhibitory Effects of Bamboo Leaf on the Growth of Pyricularia grisea Fungus

In this study, the effects of bamboo leaf were examined on mycelial growth of Pyricularia grisea, a fungus of rice blast disease that causes a great loss in rice production. The hexane extract exhibited maximal reduction on growth of P. grisea (IC50 = 0.62 mg/mL), followed by aqueous and ethyl acetate extracts, while the methanol extract was least effective (IC50 = 9.71 mg/mL). At 0.5–1.0 mg/mL doses, all extracting solvents showed inhibition on the growth of P. grisea, but at a 0.1 mg/mL concentration, the antifungal activity was solely observed on hexane and ethyl acetate extracts. By GC-MS (gas chromatography-mass spectrometry), 25 constituents were identified, principally belonging to long-chain fatty acids, sterols, phenols, phenolic acids, volatile oils, and derivatives of terpenes. It was suggested that compounds originated from hexane and ethyl acetate extracts such as fatty acids, oils, and phenols, and their derivatives were responsible for the antifungal activity of bamboo leaf. Non-polar constituents were accountable for the antifungal activity, although water-soluble compounds may play a role. Bamboo leaf appears to be a potent natural source to manage the infestation of P. grisea in rice cultivation.