Chemical compounds from Azadirachta indica as inhibitors of potato virus X

Abstract

Two chemical compounds, nimbin and nimbidin, known to occur in neem (A. indica) oil, were tested for their antiviral activity against potato virus X (PVX). Nimbidin at 1000 ppm inhibited the virus by 62.0% whereas nimbin at the same concentration inhibited the virus less than 50%. Pre- and postinoculation sprays of Chenopodium amaranticolor leaves with these chemicals were quite effective in inhibiting local lesion formation. Preinoculation root treatment of tomato seedlings with 500 ppm of both compounds did not delay the appearance of the disease symptoms. Preinoculation root treatment of C. amaranticolor seedlings with a mixture of both compounds at a concentration of 250 ppm or of nimbidin at 500 ppm resulted in 65 and 35% inhibitions of local lesions, respectively.