Antimicrobial, mosquito larvicidal and antioxidant properties of the leaf and rhizome of Hedychium coronarium

Abstract

The essential oil, methanolic and aqueous extracts of the leaves and rhizomes of Hedychium coronarium Koen. (Zingiberaceae) were assayed for their antimicrobial, mosquito larvicidal and antioxidant properties. The chemical composition of the essential oil of two organs was analyzed by GC/MS analysis. β-Pinene (33.9%), a-pinene (14.7%), 1,8-cineole (13.3%), r-elemene (11.0%) and carotol (9.1%) were the main components in the leaf oil, including 82.0% terpenoid compounds. The major constituents of the rhizome oil were 1,8-cineole (37.3%), P-pinene (23.0%), α-terpineol (10.4%) and apinene (9.9%), comprising 80.6% of the oil. The leaf and rhizome essential oil displayed significant antimicrobial activity, as determined by the disc-diffusion method, inhibiting the growth of all five fungal and four bacterial strains tested. The antimicrobial nature of the essential oil is related to high terpenoid contents. The leaf oil exhibited the mosquito larvicidal activity with 2 h and 24 h LC50 values of 111 and 90 ppm, respectively, while the rhizome oil showed the larvicidal activity with 2 h and 24 h LC50 values of 86 and 47 ppm, respectively. β-Pinene, a-pinene and 1,8-cineol in H, coronarium serve as the principal larvicidal components of both oils. The individual antioxidant assays such as DPPH scavenging activity, chelating effect of ferrous ions and reducing power have been used. The present study demonstrated that the polar extracts of H. coronarium possessed anti-oxidant. Appreciable total phenolic content (18.5-26.3 mg/g) was also detected by Folin-Ciocalteu test.