Insecticidal Activity and Free Radical Scavenging Properties of Isolated Phytoconstituents from the Saudi Plant (Hochst.).

Chromatographic purification of the alcoholic extract from the aerial parts of the Saudi plant (Hochst.), Benth., resulted in five isolated phenolic compounds. Two flavones, hispidulin () and jaceosidin (), and the phenylethanoid glycosides, verbascoside (), isoverbascoside (), and conandroside (), were identified and their chemical structures were determined by spectroscopic analyses. The insecticidal activity of compounds and in addition to 11 compounds isolated in a previous research (-), was evaluated against the Yellow Fever mosquito, . Four compounds displayed adulticidal activity with LD values of 2-2.3 μg/mosquito. Free radical scavenging properties of the plant extracts and compounds (-) were evaluated by measuring the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonate radical cation (ABTS) scavenging activity. All compounds exhibited notable activity, compared with the positive control, l-Ascorbic acid. This study suggests that could be a promising source of secondary metabolites, some with lethal adulticidal effect against .