ANTIFEEDANT ACTIVITY OF ETHANOLIC EXTRACT FROM FLOURENSIA OOLEPIS AND ISOLATION OF PINOCEMBRIN AS ITS ACTIVE PRINCIPLE

GEORGINA N. DIAZ NAPAL; MARÍA C. CARPINELLA; SARA M. PALACIOS

Termas de Chillán. Chile

Simposio; VI International Symposium on Natural Products and its Applications.; 2007

The ethanolic extract from Flourensia oolepis aerial parts showed strong antifeedant activity against the pest larvae, Epilachna paenulata, with an antifeedant index (AI% ) of 99.1% at 100 mg/cm2. Through a bio-guide chromatographic fractionation of the extract, led by bioassays on E. paenulata, the flavanone pinocembrin (1) was isolated as the most active principle. In a choice assay, compound 1 showed strong antifeedant activity against E. paenulata, Xanthogaleruca luteola and Spodoptera frugiperda with an AI% of  90, 94 and 91% (p< 0.01) respectively, at 50 mg/cm2.  The dosages necessary for 50% feeding inhibition of the insects (ED50) were 7.98, 6.13 and 8.86 mg/cm2, respectively. The feeding inhibitory activity of  1 against E. paenulata  was compared with the activity of other structurally related flavanoids like naringenin, which was inactive up to 100 mg/cm2, catechin which was nearly 6 times less active than 1, and quercetin which was 30 times more active than 1. At doses below the ED50,  1 was inactive while 3 and 4 showed feeding stimulant activity.             1                                 2                                       3                                       4