Identification of antifungal compounds in the spent mushroom substrate of .

In view of the possibility that spent mushroom substrates (SMSs) may be used as agricultural materials to prevent crop diseases, we examined the effect of treatment with a hot water extract from the SMS of on plant resistance to pathogenic infection. The extract of SMS was sprayed onto the leaves of rice plants, followed by inoculation of the leaves with the conidia of rice blast fungus. The development of lesions was suppressed by treatment with the SMS extract. The extract markedly inhibited the germination of conidia. We purified compounds , , and , which showed inhibitory effects on conidial germination, from the SMS extract of by successive solvent extraction, column chromatography, and preparative HPLC. Spectroscopic analyses revealed that , , and were phenolic acids with two carboxyl groups in common.