The polyphenol content of Curcuma xanthorrhiza has an antioxidant capacity. The potential of the antioxidant activity of plant extracts can be increased by accumulating more polyphenolic compounds. NPK fertilizer has the potential to increase the phytochemical content of plants. The present experiment was aimed at evaluating the polyphenol content and antioxidant activity of the methanolic extract of C. xanthorrhiza. The total phenolic content was estimated using the Folin-Ciocalteu method, and the total flavonoid content was evaluated using the AlCl3- colourimetric method. Antioxidant activity in the methanolic extract of C. xanthorrhiza was analysed using four methods. The greatest increases in phenolics and flavonoids were observed in the NPK treatment, at 34.54 mg GAE/g dry weight and 50.00 mg Quercetin Equivalent/g dry weight, respectively. Moreover, the application of combined N, P, and K fertilizers was found to increase the antioxidant activity of C. xanthorrhiza. The PK treatment exhibited the highest antioxidant activity, as determined by the DPPH method (147.33 TE/g dry weight), while the NPK treatment yielded the highest antioxidant activity according to the ABTS and Cupric reducing antioxidant capacity methods, at 261.67 μmoL TE/g dry weight and μmol TE/g dry weight, respectively. In contrast, the NK treatment produced the highest antioxidant activity based on the Ferric reducing antioxidant power assay method, at 43.24 μmoL TE/g dry weight. The correlation analysis showed a positive-strong relationship between polyphenols and antioxidant capacity in the methanolic extract of C. xanthorrhiza. This study revealed the role of NPK in increasing the biochemical content and antioxidant properties of C. xanthorrhiza.
Key words: Polyphenols; antioxidant activity; methanol extract; medicinal plant; NPK fertilizer
|
