INSECT GROWTH-INHIBITORS FROM MACHILUS-JAPONICA

The neolignans, licarin A[(2R,3S,4R,5R)-2-(3,4-dimethoxyphenyl)-3,4-dimethyl-5-piperonyltetrahydro-furan],( -)-machilusin and (2S,3S)-2,3-dihydro-7-methoxy-3- methyl-2-(3,4-dimethoxyphenyl)-5-trans(1-propenyl)-benzofuran], 5-trans-(l-propenyl)benzofuran], were identified as bioactive constituents in leaves of Japanese Machilus japonica. All compounds exhibited growth inhibition activity against larvae of the insect Spodoptera litura. The most abundant constituent was (2R,3S,4R,5R)-2-(3,4-dimethoxyphenyl)-3,4-dimethyl-5-piperonyltetrahydrofuran] (0.05% dry wt), a new natural product, while [(2S,3S)-2,3-dihydro-7-methoxy-3-methyl-2-(3,4-dimethoxyphenyl)- 5-trans-(1-propenyl)-benzofuran] had the highest activity against the test insect (0.01% dry wt, EC(50)=0.13%w/w). A possible synergistic action of these compounds with other M. japonica components is discussed.