Chemical and biological similarities between root extracts from Phak paem (Acanthopanax trifoliatus) and Siberian ginseng (Acanthopanax senticosus)

Extracts from the roots of Phak paem (Acanthopanax trifoliatus) collected from 3 different provinces in Thailand, i.e., Chiang Mai, Nakhon Ratchasima and Pathum Thani and extracts from the roots of Siberian ginseng (Acanthopanax senticosus) purchased from China and authentic Siberian ginseng roots were prepared by decoction and refluxing with 75% ethanol. All extracts were tested for in vitro antioxidant activities using DPPH scavenging assay, FRAP assay and TBARS method. Aqueous and 75% ethanolic root extracts from Phak paem collected from Nakhon Ratchasima (ATS2D and ATS2R, respectively) exhibited stronger DPPH scavenging activities than others with EC₅₀ of 43.34 ± 1.22 and 33.78 ± 0.70 µg/ml, respectively. All extracts showed no difference in reducing powers. Extracts from Siberian ginseng showed higher effects to inhibit lipid peroxidation. Phytochemical analysis by HPLC-DAD showed that root extracts from Phak paem and Siberian ginseng had similar chromatographic fingerprints. The main constituents identified by comparison of retention times and absorbance spectra were polyphenolic compounds of caffeoylquinic acid derivatives including chlorogenic acid, cynarin, 3,5-dicaffeoylquinic acid, 1,4-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid which also showed antioxidant effects. Quantitative analysis by HPLC revealed that ATS2D and ATS2R contained higher active constituents than those collected from other provinces, the phenolic contents were 4.80 ± 0.02 and 8.94 ± 0.03 g in 100 g extracts, respectively, similar to phenolic contents in aqueous and 75% ethanolic root extracts from authentic Siberian ginseng roots which were 4.97 ± 0.14 and 11.63 ± 0.08 g in 100 g extracts, respectively. The results suggest that the roots of Phak paem have potential in chemical and antioxidant properties similar to Siberian ginseng which could be beneficial for further pharmaceutical purposes. However, harvesting areas also play an important role to the quality of raw material.