Comparative Qualitative and Quantitative Phytochemical Screening of Hibiscus sabdariffa (Linn.) and Allium sativum (Linn.) Crude Extracts

Abstract

Medicinal plants remain an important source of bioactive compounds with therapeutic potential, particularly in resource-limited regions where access to orthodox medicine is constrained. This study evaluated the phytochemical composition of Hibiscus sabdariffa (Roselle) calyces and Allium sativum (Garlic) bulbs from Kaduna, Nigeria, through solvent extraction, qualitative screening, and quantitative phytochemical assays. Ethanolic extraction of H. sabdariffa and methanolic extraction of A. sativum yielded 17.04% and 4.69% (w/w), respectively, followed by column chromatographic fractionation using hexane/ethyl acetate and ethyl acetate/methanol gradients, yielding seven pooled fractions from roselle (R1-R7) and five from garlic (G1-G5). Qualitative screening confirmed saponins, alkaloids, flavonoids, tannins, cardiac glycosides, and terpenes in both plants, with anthraquinones detected only in roselle. Quantitative analysis showed roselle contained significantly higher alkaloids (876.78 +/- 12.4 vs 629.26 +/- 10.8 mg/g, p < 0.001), flavonoids (288.63 +/- 6.2 vs 233.13 +/- 5.7 mg QE/g, p < 0.001), polyphenols (6.61 +/- 0.3 vs 4.88 +/- 0.2 mg GAE/g, p < 0.01), and tannins (13.88 +/- 0.8 vs 9.42 +/- 0.5 mg TAE/g, p < 0.01) than garlic, while saponin content did not differ significantly (52.14 +/- 3.1 vs 49.76 +/- 2.9 mg/g, p > 0.05). This is among the first studies to directly compare the phytochemical yield and fractionation profile of Nigerian-grown H. sabdariffa and A. sativum under standardised conditions, providing a quantitative baseline for future bioactivity-directed isolation of compounds from these widely consumed Nigerian plants.