Chemical composition and antioxidant activity of Acorus calamus L. accessions from different ecological niches

Abstract

The essential oil composition of Acorus calamus (Acoraceae) rhizomes, collected from twenty different ecological niches in Uttarakhand, India, with an oil yield ranging between 0.7–5.4% (v/w), was examined by GC/MS. Among the identified components, β-asarone (62.3–75.9%), α-asarone (2.2–6.1%), Z-isoelemicin (2.4–6.2%), Z-methyl isoeugenol (2.3–6.4%) and shyobunone (1.5–5.3%) were found to be the major ones. The antioxidant activity of different essential oils was compared to that of standard antioxidants to assess their free radical scavenging potential, metal chelating ability, and reducing power. The essential oils exhibited significant in vitro antioxidant activity. The IC₅₀ values for DPPH radical scavenging, metal chelating, and reducing ability exhibited by the rhizomes essential oils were observed between 22.28–61.96 μg/mL, 29.55–159.26 μg/mL, and 21.41–61.19 μg/mL, respectively. Based on the above observations, the chemical diversity of A. calamus essential oil can be a good source of herbal nutraceuticals and phenylpropanoids. The possible mode of action and structure-activity relationship between major compounds of essential oils and proteins of antioxidant activity were studied using in-silico molecular docking and were found to support the in-vitro results.