RESUMO
Four quassinoids, indaquassin C (1), samaderins C (2), B (3) and A (4), isolated from the seeds and bark of Samadera indica, were tested for insect antifeedant and growth regulatory activities against the tobacco cutworm, Spodoptera litura. Indaquassin C was the most effective antifeedant. Samaderin C increased pupal duration and induced pupal mortality.
Assuntos
Comportamento Alimentar/efeitos dos fármacos , Glaucarubina/farmacologia , Inseticidas/farmacologia , Quassinas , Rosales , Spodoptera/efeitos dos fármacos , Triterpenos/farmacologia , Animais , Glaucarubina/análogos & derivados , Glaucarubina/química , Inseticidas/química , Larva/efeitos dos fármacos , Caules de Planta , Sementes , Triterpenos/químicaRESUMO
Natural tetranortriterpenoids such as cedrelone from Toona ciliata, azadiradione from Azadirachta indica, limonin, limonol and nomilinic acid from Citrus medica, along with some cedrelone derivatives were tested for their antifungal activity against Puccinia arachidis, a groundnut rust pathogen. Results show that cedrelone was the most effective in reducing rust pustule emergence. Replacement of functional groups or modification of the A or the B ring in cedrelone reduced the effectiveness indicating the importance of specific structural features for activity.
Assuntos
Antifúngicos/farmacologia , Fungos/efeitos dos fármacos , Doenças das Plantas , Extratos Vegetais/farmacologia , Plantas Medicinais , Triterpenos/farmacologia , Testes de Sensibilidade MicrobianaRESUMO
The antifeedant and insect growth-regulating activities of salannin, nimbin, and 6-deacetylnimbin, in comparison with azadirachtin-A, have been studied againstSpodoptera litura, Pericallia ricini, andOxya fuscovittata. Salannin deterred feeding, delayed molt by increasing larval duration, caused larval and pupal mortalities, and decreased pupal weights in the two lepidopterans. Salannin also caused molt delays and nymphal mortalities inOxya fuscovittata. The role of salannin and other compounds in conferring bioactivity, along with azadirachtin-A, to neem oil/neem seed extracts is emphasized.
RESUMO
Insect antifeedant and growth-regulating activities of 22 limonoids (both natural and their derivatives) againstSpodoptera litura were studied to understand the structure-related bioactivities of the limonoids. The C-seco limonoids (azadirachtins A, B, D, H, and I) were the most effective compounds as a group, while the intact limonoids (cedrelone and its derivatives) were the least effective. The cyclohexenone A ring and theα-hydroxy enone group in the B ring appear to be important for antifeedant activity. The presence of a cyclohexenone or 1,2-epoxide in the A ring coupled with anα-hydroxy enone in the B ring correlated well with growth regulatory activity. An acetoxy at C-7 instead ofα-hydroxy enone and perhaps the carbonyl at C-16 increase growth regulatory activity. Absence of 14-15 epoxide may not drastically reduce antifeedant activity and growth regulatory activity.
