Effects of Neem Seed Derivatives on Brown Planthopper Symbiotes

Populations of intracellular symbiotes declined significantly in brachypterous females of the brown planthopper,Nilaparvata lugens (Stål), which were stressed during nymphal development by caging them on IR20 rice plants treated with 3% neem oil, 5% neem seed kernel aqueous extract, or 10% neem cake aqueous extract. In addition, nymphs grew poorly and symbiote populations in prospective females declined, when reared on rice plants grown in soil treated with neem cake; this indicates systemic action of bioac-tive neem constituents. Addition of custard-apple oil to neem oil did not enhance the inhibitory effects. The effects of neem derivatives on the symbiotes may be either host-mediated — possibly through disturbed neuroendocrine homeostasis, or direct — leading to perturbations of host-symbiote equilibrium.     

Antiviral activity of sulfated polysaccharides from Sargassum ilicifolium against fish Betanodavirus infection

Sulfated polysaccharides (SP) from seaweeds exhibit numerous biological activities and are less toxic than conventional antiviral drugs. However, little is known about their mode of action. This study aims at extracting the polysaccharides from brown seaweed Sargassum ilicifolium and then evaluating its antiviral activity against fish Betanodavirus. The extracted SP was characterized through FT-IR, ¹H NMR, and thermal gravimetric analysis (TGA). The antiviral activity of SP was tested on SGA cell line by syncytia reduction and the polysaccharide represented a prominent antiviral activity to Betanodavirus by reducing the cytopathic effect (CPE) formation in vitro. The study revealed that SP effectively blocked viral attachment and entry. Moreover, during the in vivo challenge experiment in Gambusia affinis, SP treatment showed a significant decrease in the viral titers. Hence, these results indicate that the polysaccharides obtained from S. ilicifolium exhibited the high antiviral potential to Betanodavirus infection in fishes both in vitro and in vivo.