HIBISCUS POLYPHENOLS AND ANTHOCYANINS: ISOLATION, CHARACTERIZATION, AND PHARMACOGNOSTIC SIGNIFICANCE—A FOCUS ON HIBISCUS SABDARIFFA AND HIBISCUS ROSA-SINENSIS

Introduction: This review examines the phytochemical composition, extraction methods, pharmacological activities, quality-control requirements, and safety considerations of Hibiscus sabdariffa and Hibiscus rosa-sinensis. Objective: To compare the major phytochemical constituents, extraction strategies, analytical characterization techniques, pharmacological evidence, and quality-control parameters between the two species to identify research gaps and translational opportunities. Materials and Methods: A narrative synthesis of botanical, pharmacognostic, analytical, and biomedical literature was conducted to compare major constituents, extraction strategies, characterization techniques, and reported biological effects across both species. Findings: H. sabdariffa contains abundant anthocyanins, especially delphinidin- and cyanidin-based sambubiosides, along with phenolic acids and organic acids that support antioxidant and cardiovascular activity. H. rosa-sinensis shows broader cultivar- and part-dependent variation, with anthocyanins, flavonoids, phenolic acids, and triterpenoids reported in flowers and other tissues. Extraction efficiency depends on solvent choice, temperature, pH, and processing conditions, while HPLC and LC–MS remain the most reliable methods for standardization. Preclinical studies suggest antioxidant, anti-inflammatory, antimicrobial, metabolic, and anticancer potential, with the strongest human evidence supporting roselle's blood-pressure-lowering effect. Conclusion: Hibiscus sabdariffa has the clearest translational promise, but both species require standardized extracts, stronger clinical evidence, and more complete safety evaluation to support regulatory acceptance and wider therapeutic applications in evidence-based healthcare.