Momilactone B and Potential in Biological Control of Weeds

Rice has been known to release allelochemical(s) into the surroundings and has been demonstrated by numerous studies conducted within both lab-scale and field-scale. Many potential allelochemicals in rice include fatty acids, phenolic acids, hydroxamic acids, phenylalkanoic acids, terpenes, momilactones, and indoles. In this review, the role of labdane-related diterpenoid momilactones, typically momilactone B (MB), is highlighted as the principle allelochemical in rice plants. During the plant wheel of life, momilactone B is excreted from the roots to inhibit weeds. Structurally, momilactone B is also a phenol which differs from momilactone A (MA) and other momilactones by an oxygen bridge, where the −OH is attached to the C3 of the benzene ring. Basically, the amount of MB is less than MB in all plant parts in rice, but its biological activity, especially weed suppression level, is more excellent than MA. The synthesis of function group from MB is potential for development of novel herbicides in agricultural production.