Abstract

Essential oils of the fruits of three cultivars of Amomum subulatum (Family-Zingiberaceae), such as varlangy, seremna and sawney were isolated. Antioxidant potential was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) scavenging and FeCl₃-reducing models and the presence of 1,8-Cineole was quantified using the developed high performance thin layer chromatography (HPTLC) method. In the DPPH scavenging model, the IC₅₀ value of the essential oil of the seremna, varlangy and sawney were found to be 172.3, 216.9 and 274.3 μg/ml, respectively, while in the ABTS scavenging model, the IC₅₀ value of the seremna, varlangy and sawney were found to be 27.96, 31.34 and 32.49 μg/ml respectively. The antioxidant power of the FeCl₃ reducing model, the absorbance value of the essential oil of the seremna was found comparatively higher than the essential oils of varlangy and sawney. The content of 1,8-cineole was determined by the developed HPTLC densitometric method, and the value of the percentage (mean ± SD, % w/w) content of the essential oils  of the seremna, varlangy and sawney were found to be 69.59 ± 1.45%, 48.78 ± 3.21 and  47.84 ± 1.76 respectively. The highest antioxidant value of seremna cultivar may be due to the presence of high content of 1, 8-cineole. The HPTLC method, therefore confirms that monoterpene 1,8-cineole is the main antioxidant compound present in the fruits of A. subulatum.

Key words: Amomum subulatum, cultivars, essential oil, 1,8-cineole, high performance thin layer chromatography (HPTLC), antioxidants.