Identification of marker compounds and antioxidant activity of Terminalia chebula Retz. fruit pericarps used in selected commercial herbal preparations in Sri Lanka

Abstract

Medicinal plants contain phyto-constituents which show pharmacological effects. This study is focused on identification and quantification of marker compounds and determination of the antioxidant activity of T. chebula Retz. fruit pericarps used in selected commercial herbal preparations in Sri Lanka. Commercial samples were obtained from Sri Lanka (SLC) and India (INC), separately from three different batches of T. chebula stocks from raw material quarantine section at Link Natural Products (Pvt) Ltd. As these commercial samples are a mixture of fruits from wider geographical locations, five samples (SLA) collected from known locations in Sri Lanka were included for comparison. Methanolic extracts (70 % v/v) were prepared from each sample. Chromatographic profiling was done using thin layer chromatography (TLC) and high- performance liquid chromatography (HPLC). Extracts were assayed for gallic acid content, total tannin content and antioxidant activity. Gallic acid and ellagic acid could be used as marker compounds in quality control of T. chebula commercial stocks. All samples had a low IC50 value than butylated hydroxytoluene (BHT) standard showing that T. chebula fruit pericarps have higher antioxidant activity than BHT. Variations in IC50 values were observed within and among SLA, SLC and INC suggesting that both intrinsic and extrinsic factors may lead to the change in antioxidant potential of the fruits. The mean IC50 value of SLC samples was (6.32 ± 2.09) µg/mL whereas that of INC samples was (7.42 ± 0.93) µg/mL suggesting that antioxidant activity was higher in SLC samples over INC samples. A variation in antioxidant activity in SLA samples was observed, depending on the sampling site.