This Hair it is bright disclose Yi Seed System Prepare from childhood the extract of mulberry Trees (Morus australisPoir.) root skin and by wherein Fen From go out Come have the formula (antibacterial application of the Kuwanon H compounds of I) structures(I).本發明揭示一種製備自小桑樹(Morus australisPoir.)根皮的萃取物及由其中分離出來的具有式(I)結構的Kuwanon H化合物的抗菌用途(I)。