Phytochemical Screening and Antioxidant Activity of Piper Nigrum and Aframomum Melegueta Seeds Extracts

Abstract

Natural products remain a vital source of bioactive compounds with therapeutic potential, particularly in the management of oxidative stress-related diseases. This study evaluated the phytochemical composition and antioxidant activity of seed extracts of Piper nigrum and Aframomum melegueta. Dried and pulverized seeds were subjected to successive solvent extraction using n-hexane, ethyl acetate, and methanol. Qualitative phytochemical screening, such as tests for flavonoids, tannins, saponins, reducing sugars, alkaloids, anthraquinones, and steroids on the extracts, was conducted using standard methods, and antioxidant activity was assessed by the DPPH free radical scavenging assay, with ascorbic acid as the reference standard.  Both plant extracts exhibited appreciable yields: P. nigrum (4.26 %) and A. melegueta (4.57 %), and contained diverse phytochemicals, including flavonoids, alkaloids, tannins, steroids, and anthraquinones. Antioxidant analysis revealed concentration-dependent radical scavenging activity across all fractions. A. melegueta demonstrated superior antioxidant activity, with IC₅₀ values (0.4224-0.4398 mg/mL) comparable to ascorbic acid (0.3656 mg/mL), whereas P. nigrum showed moderate activity (IC₅₀: 0.5766 - 1.0276 mg/mL).  These findings indicate that both plants are rich in bioactive compounds with significant antioxidant potential, with A. melegueta exhibiting greater efficacy. The study supports their traditional medicinal use in treating oxidative diseases and highlights their potential as natural antioxidant sources for pharmaceutical and nutraceutical applications.