Potent Insecticidal Secondary Metabolites from the Medicinal Plant Acanthus montanus

Acanthus montanus (Nees) T. Anders. (Family: Acanthaceae) is a small shrub with sparse branches and soft stems, widespread in Africa, the Balkans, Romania, Greece and Eastern Mediterranean. Documented evidence showed that the leaves of the plant possess spasmolytic, analgesic, anti-inflammatory and antipyretic activities. In our ongoing research project; aimed at identifying new natural compounds with insecticidal activity, the alcohol extract of the aerial parts of A. montanus exhibited a significant activity against adult Aedes aegypti. Phytochemical study of the plant has resulted in isolation of nine compounds, eight of which exhibit variable degrees of insecticidal activity. β-sitosterol-3-O- β –D-glucoside (1) exhibited potent mosquitocidal activity (100% mortality) against adult Aedes aegypti at 1.25 μg/mg concentration, followed by palmitic acid (2) (90%), linaroside (3) (80%), and acetoside (9) (70%) respectively. It is noteworthy that this is the first report of insecticidal activity of β-sitosterol-3-O- β –D-glucoside, linaroside and acetoside.