Mensah and Golomeke / Current Science Perspectives 1(2) (2015) 69-76 69 Article type: Research article Article history: Received February 2015 Accepted April 2015 April 2015 Issue Keywords: Hibiscus sabdariffa Linn TAC DPPH Agar diffusion Broth dilution The calyces of Hibiscus sabdariffa Linn are widely used for nutritional and medicinal purposes in Ghana. This study assessed the antioxidant and antimicrobial activities of the aqueous and the ethanol (hydro-ethanol) extracts (30%) of the calyces of H. sabdariffa Linn. The hydro-ethanol extract exhibited a more potent antioxidant potential versus aqueous extract as demonstrated by its higher Total Antioxidant Capacity (TAC) and its lower EC 50 for both the DPPH and the Hydroxyl radical scavenging activities. Additionally, the hydro-ethanolic extract displayed more potent antimicrobial activities with larger zones of inhibition in the agar diffusion assay and lower MICs in the broth dilution assay against a set of microorganisms including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. The data supports the ethnomedicinal use of the aqueous infusion of H. sabdariffa Linn for the management of urinary tract infections and other symptoms that may be linked to oxidative stress. © 2015 International Scientific Organization: All rights reserved. Capsule Summary: The antioxidant and antimicrobial activities of the aqueous and ethanol (hydro-ethanol) of Hibiscus sabdariffa were assessed. Results showed that hydro-ethanol extracts showed higher antioxidant activity in terms of TAC, EC50 and DPPH as well as antimicrobial activity against set of microbes. Cite This Article As: John Kenneth Mensah and Divine Golomeke. Antioxidant and antimicrobial activities of the extracts of the Calyx of Hibiscus Sabdariffa Linn. Current Science Perspectives 1(2) (2015) 69-76 INTRODUCTION Oxidative stress and cellular metabolism generates reactive oxygen species (ROS) that contributes to the etiology, pathogenesis and progression of several diseases including inflammations, cancer, and cardiovascular diseases (Stanner et al., 2002). Dietary antioxidants can inactivate ROS and provide protection from oxidative damage and are therefore considered important therapeutic and prophylactic agents against disease development (Farrukh and Mukhtar, 2002). Additionally, escalating levels of antibiotic resistance strains of pathogenic microorganisms necessitates the search for new antibiotics with high therapeutic potential. Therefore, screening dietary sources of natural products for novel antimicrobial agents is a priority. H. Sabdariffa Linn is a multi-purpose plant used widely for nutritional and medicinal purposes throughout West Africa (Dokosi, 1998; Qi et al., 2000). The calyces are phytochemical rich and have been shown to contain bright red-pigmented flavonoids (Ali et al., 2005). Prior studies have confirmed the presence of glycosides, flavonoids, saponins, essential oils, saponosides, triterpenes, coumarins, tannins, sugars, steroids, tritepene glycosides, and polyphenolic compounds as phytoconstituents in the calyces of H. sabdariffa (Ali et al., 2005). Aqueous decoction of the calyx of H. Sabdariffais used for food coloring (Frimpong et al., 2014) and for the preparation of a soft drink widely consumed for varied health benefits (Fasoyiro et al., 2005; Fasoyiro et al., 2005). Prior studies have demonstrated that the calyx extracts of H. sabdariffa are anti- Current Science Perspectives 1(2) (2015) 69-76 Antioxidant and antimicrobial activities of the extracts of the Calyx of Hibiscus Sabdariffa Linn John Kenneth Mensah* and Divine Golomeke Chemistry Department, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana *Corresponding author’s E-mail: jkmensah75@yahoo.com ARTICLE INFO A B S T R A C T