PHYTOCHEMICAL PROFILING, ANTIOXIDANT, ANTITYROSINASE AND ANTIPLASMODIAL ACTIVITIES OF CHLOROFORM AND N-BUTANOL STEM FRACTIONS OF PARQUETINA NIGRESCENS (AFZEL.) BULLOCK: A COMPARATIVE STUDY

The therapeutic potential of the solvent partitioned fractions of Parquetina nigrescens (Afzel.) Bullock was evaluated using an integrated approach that included phytochemical screening, GC-MS analysis, antioxidant, antityrosinase, antimalarial, and cytotoxicity assays. The methanolic extract of the stem was subjected to successive partitioning using chloroform and n-butanol solvents. The phytochemical screening of the chloroform and n-butanol fractions showed the presence of alkaloids, flavonoids, phenolic, and terpenoid compounds, whereas the n-butanol fraction was predominantly rich in tannins and saponins. The GC-MS analysis identified 33 and 8 compounds from the chloroform and n-butanol fractions, respectively, which included fatty acid methyl esters, diterpenoids, and hydrocarbons. The fractions demonstrated moderate DPPH radical scavenging activity (IC50: 71.25 ± 1.05 µg/mL for chloroform fractions; 66.59 ± 1.40 µg/mL for n-butanol fractions) and nitric oxide scavenging activity (IC50: 71.45 ± 0.86 µg/mL for chloroform fractions; 73.17 ± 1.42 µg/mL for n-butanol fractions). The n-butanol fraction exhibited strong tyrosinase inhibition (IC50: 54.39 ± 1.30 µg/mL), surpassing kojic acid. Both fractions showed significant activity against Plasmodium falciparum (IC50 range: 3.224–3.611 µg/mL) with cytotoxicity IC50 values above 30 µg/mL on HeLa cells, yielding selectivity indices greater than 10. The pharmacological relevance of the fractions and the bioassay results validate the utility of the solvent partition method for the fractionation of P. nigrescens. The results also show the potential of the chloroform and n-butanol fractions as lead compounds for the development of antimalarial and tyrosinase inhibitors.