Isolation and purification of antifeedant and antioviposition substances against the diamondback moth from a tropical plant.

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In 1994, antifeedant activity of the acetone extract from A.paniculata against the 1st- and 4th-instar larvae of the diamondback moth (DBM), P.xylostella, was observed at 60 ppm and 500 ppm respectively. Antioviposition effect on the DBM females was also observed on caged cabbage treated with these extracts at 125 ppm.In 1995, a series of fractionation of the aerial parts of A.paniculata guided by a no-choice bioassay test on the 4th-instar larvae of the DBM was conducted for the isolation of the hexane, ETOAc, BuOH and water layrs. Subsequent bioassay tests showed that the hexane layr is the most potent antifeedant against the DBM larvae. Futher fractionation of the hexane layr yielded 7 fractions. Fractions 5 and 6 were still effective even at a reduced dose (50 mug/leaf disc). Thus, fraction 5 was subsequently fractionated and 5 sub-fractions (F5-1 to F5-5) were obtained. Among those F5-2 was the most effective feeding deterrent at a minimum dose of 25mug/leaf disc. Through preparative TLC,an active compound (F526) was finally purified and isolated from F5-2. Further chemical analysis using other analytical procedures will be done to determine the chemical structure of this active compound.