Phytochemicals Profile and Antioxidant Potency of <i>Hyptis Suaveolens</i> (L) Poit and <i>Hyptis Spicigera</i> Lam Traditionally Used for Malaria Control in Nigeria

Abstract

Biologically active compounds have always been of great interest to medical and public health parasitologists. The present study was carried out to determine the phytochemical constituents, the efficacy of extraction solvents, and the antioxidant activity of the leaf extracts of Hyptis suaveolens and Hyptis spicigera, two plants traditionally used for the direct control of malaria vector, Anopheles gambiae s.s., in Nigeria. Hyptis suaveolens and Hyptis spicigera plants were collected, identified, processed, and extracted according to established standard protocols. Aqueous and methanolic extracts of leaves and roots were subjected to qualitative and quantitative phytochemical screening using standard methods. Antioxidant potentials were evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) bioassay. Key metabolites identified included alkaloids, flavonoids, terpenoids, cardiac glycosides, steroids, tannins, and saponins. The identified alkaloids, terpenoids, and flavonoids have been shown to have strong mosquitocidal and antiplasmodial activity, capable of controlling mosquitoes directly and malaria indirectly. Quantitative results from H. suaveolens aqueous leaf extract showed terpenoids (4.091 mg/100g), saponins (4.005 mg/100g), and flavonoids (3.882 mg/100g) as dominant compounds. Methanolic leaf extract recorded higher concentrations, with saponins (6.180 mg/100g) and terpenoids (5.351 mg/100g) being prominent. Similarly, H. spicigera aqueous leaf extract revealed cardiac glycosides (2.503 mg/100g) and saponins (2.140 mg/100g), while methanolic root extracts showed flavonoids (2.354 mg/100g) and terpenoids (2.774 mg/100g). The plant extract also showed strong antioxidant activity, as evidenced by its ability to scavenge free radicals. The analysis showed that methanolic leaf extracts exhibited 80.0% and 86.81% inhibition in Hyptis suaveolens and Hyptis spicigera, respectively. The IC50 values were 34.02 μg/ml and 22.05 μg/ml for Hyptis suaveolens and Hyptis spicigera, respectively; as such, Hyptis spicigera appeared more potent than Hyptis suaveolens. Comparatively, methanolic solvents yielded higher phytochemicals than aqueous solvents in both the leaf and the roots for the two plants under studied. Future research shall conduct larvicidal and adulticidal bioassays to test the mosquitocidal efficacy of the crude extract of the two Hyptis species studied.