Identification, quantification and nutraceutical evaluation of the extracts from Arnebia benthamii roots of Himalayan regions of J&K, India

Arnebia benthamii is one of the important sources of biologically active naphthoquinone pigments. The present study aimed at extraction of shikonin from Arnebia benthamii roots and its characterization. In order to identify and quantify shikonin, the extracts were evaluated using HPLC, LCMS, GCMS, NP-HPTLC and FTIR. Furthermore, nutraceutical evaluation was also done. It was found that the amount of shikonin was very low in the extracts obtained by using aqueous ethanol as it was not detected through chromatographic techniques. However, when hexane was used for extraction, a significant amount of shikonin (4.55 mg/g) was detected. The shikonin showed a linear range from 2-55 µg/mL with LOD and LOQ of 2.65 and 8.02 respectively, with a retention time of 3.64 min. The results of FTIR revealed that hexane extract had the intensity of functional groups similar to that of the standard. The values of DPPH radical inhibition were observed as 82.98 ± 0.01, 65.09 ± 0.23 %, 62.28 ± 0.86 % and 54.09 ± 0.23 % for Std, Ehex, Eus and Evs, respectively. The hexane extract showed the highest antioxidant activity as compared to other samples. Moreover, the hexane extracted shikonin displayed significantly (p > 0.05) high α-amylase and pancreatic lipase inhibition, indicating its high anti-diabetic and anti-lipidemic potential. It can be concluded that hexane is the best solvent for the extraction of shikonin and has better nutraceutical potential compared to ethanolic extracts.