Phytochemical Compounds and Antioxidants Analysis of <i>Clinacanthus nutans </i>Leaf and Stem Extracts

Clinacanthus nutans consists with multiple medicinal properties. The plant is also known to be a source of biologically active compounds, particularly those with an antioxidant capacity. The phytochemical studies of C. nutans plant extract was mostly reported from its leaf part. Thus, the objectives of this study are to assess the phytochemical constituents and antioxidant activity of C. nutans leaf and stem. Methanol was used as solvent for the green extraction. Next, phytochemical screening, Fourier transform infrared (FTIR) analysis, total phenolic (TPC) and flavonoids contents (TFC), quercetin flavonoid compound analysis and in vitro antioxidant activity were performed on C. nutans leaf and stem. In comparison to stem extract, the leaf extract showed a more favorable appearance of metabolites. In FTIR analysis, both sample extracts revealed the presence of hydroxyl and carbonyl functional groups, which are important in antioxidant action. The TPC (228.06 mg GAE/g DW) and TFC (29.76 mg QE/g DW) values were higher in the leaf extract than the stem extract. Quercetin quantification in HPLC analysis revealed that the leaf extract (21.33 g/g) contained more quercetin than the stem extract (18.88 g/g). Between the extracts, leaf providing more antioxidant values of DPPH (15.50%) and FRAP (15.68 gFeSO 4 /g) than stem. The greatest association was identified between TFC and FRAP reducing activity (r = 0.977, p<0.05) indicating that the flavonoid present in the extract contributed to C. nutans' antioxidant capacity.