In vitro Antisickling Activity, Cytotoxicity and Nutritive Composition of Aqueous Calyx Extract of Hibiscus sabdariffa L. (Malvaceae)
Ololade Adesomi Oyedapo
*
Drug Research and Production Unit, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria.
Sarah Gbemisola Adewale
Department of Pharmacognosy, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria.
Christianah Mojisola Cyril-Olutayo
Drug Research and Production Unit, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria.
Francis Banjo Adewoyin
Drug Research and Production Unit, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria.
Nusirat Omotayo Omisore
Department of Pharmacology, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria.
Vivian Oyinkansola Oyedapo
Faculty of Dentistry, College of Health Sciences, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Sickle cell disease is characterised by polymerisation of deoxygenated haemoglobin S and consequent erythrocyte sickling. This study evaluated the in-vitro inhibitory and reversal antisickling activities, cytotoxicity, proximate composition and elemental composition of an aqueous calyx extract of Hibiscus sabdariffa L. The extract was evaluated at 2, 4 and 8 mg/ml using HbSS erythrocytes, with vanillic acid and P-hydroxybenzoic acid serving as positive controls for the inhibitory and reversal assays, respectively. Cytotoxicity was assessed using haemolysis and methaemoglobin formation. The extract produced inhibitory activities of 91.04%, 92.22% and 94.08% and reversal activities of 90.52%, 92.47% and 95.86% at 2, 4 and 8 mg/ml, respectively. Haemolysis remained low at 1.90%, 1.50% and 2.52%, whereas PBS-corrected methaemoglobin formation increased from 5.89% at 2 mg/ml to 24.16% at 8 mg/ml. Proximate analysis showed 57.44% carbohydrate, 11.93% protein, 10.23% ash, 7.71% fibre, 7.33% moisture and 5.36% fat. Sodium, potassium, calcium and magnesium were the principal elements detected, while manganese, zinc, chromium, lead, nickel and scandium were not detected. The findings demonstrate in vitro antisickling activity of the aqueous calyx extract but also indicate concentration-related haemoglobin oxidation, particularly at the highest tested concentration. Further mechanistic and toxicological studies are therefore required before biological or therapeutic relevance can be established.
Keywords: Hibiscus sabdariffa, sickle cell disease, antisickling activity, aqueous calyx extract, methaemoglobin, proximate composition, elemental composition