Plant growth inhibitor from the Malaysian medicinal plant Goniothalamus andersonii and related species

A crude methanol extract of Goniothalamus andersonii J. Sinclair strongly inhibited elongation of lettuce (Lactuca sativa L.) radicles. We conducted bioassay-guided purification of G. andersonii bark extract and obtained goniothalamin as the major bioactive compound. Its EC50 values against elongation of lettuce radicles and hypocotyls were 50 and 125 micromol L(-1), respectively. Among the six species tested, timothy was the most sensitive to goniothalamin. Quantification of this compound in other Goniothalamus species suggested that the plant inhibitory activity of this genus is explainable by goniothalamin, with G. calcareus as an exception.