An Insight into the Correlation between Phenolic Content and In vitro Antioxidant Activity of Calocybe Indica Extracts

Calocybe indica has been considered an essential herb, exhibiting a strong antioxidant capability. To this point, the phenolic compounds could be the primary constituent inducing such high activity. However, the phenolic-antioxidant activity correlation still needs to be understood. This study attempted to shed light on the direct linkage between phenolic compounds and antioxidant activity of the Vietnam-grown Calocybe indica for the first time. It turns out that the total amount of phenolic content is 97.67 mu g/g, which is exceptionally high in the methanol extract. Gallic acid, quercetin, quercitrin, and hesperidin account for 49.02 +/- 0.18 mu g/g, 15.36 +/- 0.24, 18.71 +/- 0.32, and 14.58 +/- 0.28 mu g/g of such activity, respectively. Such antioxidants result in an extraordinary performance in DPPH and ABTS evaluations. Indeed, the total antioxidant capacity ranges from 59.67 +/- 0.78 to 91.26 +/- 1.57 mg GA/g or from 75.25 +/- 0.32 to 88.17 +/- 0.64 mu mol AS/g, corresponding to the contents of phenolics from 24.92 +/- 0.24 to 35.28 +/- 0.33 mg GAE/g. Furthermore, flavonoid compounds have been quantified to range from 14.63 +/- 0.17 to 23.88 +/- 0.10 mg QUE/g. These results imply the prominence of Calocybe indica for biomedical applications.