Phytochemistry and Biological Activities of Hibiscus sabdariffa Leaf Extract: A Comprehensive Analysis and In Silico Approaches

Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) methods were used to simultaneously isolate and determine phytochemicals in the Hibiscus sabdariffa leaf extract. GC-MS analysis revealed the presence of oleic acid (52.05%), hexadecenoic acid (19.78%), and docosenoic acid (7.62%). LC-MS analysis identified six flavonoids and four phenolic acids. Quantitative analysis of some identified phenolic compounds (mg/g in dried leaves) showed the presence of quercetin-rutinoside (11.87), neochlorogenic acid (5.64), and quercetin (4.75). The total phenolic content of the extract, determined using the Folin-Ciocalteu assay, was 22.2 mg GAE/g. The in vitro antioxidant activity was measured by the ABTS radical cation decolorization assay (135.7 µmol trolox/g). The antibacterial activity was evaluated using the disc diffusion method against three Gram-positive bacteria and three Gram-negative bacteria. The leaves extract demonstrated antibacterial activity against all tested bacteria, with inhibition diameters ranging from 8 to 28 mm. The binding energies for ciprofloxacin, levofloxacin, and quercetin, ranging from −5.2 to −5.8, suggest strong interactions with the B subunit of DNA gyrase and the ParE subunit of topoisomerase IV. The study indicates that H. sabdariffa leaf extract has potent antioxidant and antibacterial properties. Additionally, quercetin from H. sabdariffa shows antibacterial potential against DNA gyrase and topoisomerase.