Antioxidant, Antifungal and Insecticidal Activity of Triterpenoids Spinasterol, 22,23-Dihydrospinasterol Isolated from Colocynthis (Citrullus colocynthis L.) Leaves.

Abstract Terpenoids from natural plants resources are valuable for diverse biological activities which exhibited important part in medical and agrochemicals industry. This study aimed to assess the antioxidant, antifungal and insecticidal activity of a mixture of Spinasterol, 22,23-dihydrospinasterol isolated from Citrullus colocynthis leaves. 1, 1-diphenyl-2-picrylhydrazyl (DPPH) was used to assess the antioxidant activity whereas, antifungal activity was tested by mycelium growth inhibition assay on three pathogenic fungi Magnaporthe grisea, Rhizoctonia solani and Phytophthora infestans. Insecticidal activity against Brevicoryne brassicae was also determined by using In-vitro and In-vivo assays. The outcome of the study exposed that Spinasterol, 22, 23-dihydrospinasterol afforded prominent antioxidant activity even at lower concentrations i.e. 19.98, 31.52, 36.61 and 49.76% at 0.78, 3.0, 12.5 and 50µgmL-1 respectively. However, moderate fungicidal activity of Spinasterol, 22; 23-dihydrospinasterol was recorded as being EC50 values 129.5 and 206.1µgmL-1 against R. solani and M. grisea respectively. On the other hand, Boscalid and Carbendazim being a positive control proved highly effective against all fungi except for M. grisea and P. infestans with EC50 values 868 and 272109µgmL-1 respectively. The pronounced insecticidal activity of Spinasterol, 22,23-dihydrospinasterol was afforded via residual as well as greenhouse assay being LC50 values as 42.46, 54.86, 180.9 µgmL-1 and 32.71, 42.46 and 173.8µgmL-1 at 72, 48 and 24 h respectively. The study concluded that isolated compound Spinasterol, 22,23-dihydrospinasterol possess promising antioxidant and aphicidal activity with moderate fungicidal activity which could be a suitable candidate as an alternative to synthetic pesticidal agents.