Biological screening of medicinal plants used by SCD patients in the eastern part of Madagascar for their anti-sickling and analgesic activities

Abstract

Madagascar is one of the Southern African countries where the prevalence of sickle cell disease (SCD), particularly among children younger than five years, is worrying. Malagasy SCD patients use several plant-based remedies to treat SCD and its symptoms. This study, which is a logical continuation of our previous field investigation, aims to screen the ethanol and/or aqueous extracts of some potential plant species cited by these patients for their analgesic and anti-sickling activities in order to demonstrate their efficacy in preventing SCD crisis and its symptoms. The anti-polymerization activity of the extracts was evaluated in vitro using sodium metabisulfite deoxygenated sickle hemoglobin (HbS) from SCD patients. The analgesic activity of the extracts was evaluated in vivo using acetic acid-induced writhing test in mice. 73 ethanol extracts and 73 aqueous extracts from 72 plant species were prepared for the biological screening. Among them, 15.1% (22) of the extracts showed good anti-polymerization activity at 1000 µg/mL where the ethanol extracts of Sigesbeckia orientalis (91.19%) and Mollugo nudicaulis (90.08%) demonstrated the highest activity. In addition, 69.9% (102) of the extracts at the oral dose of 200 mg/kg body weight (b.w.) showed good analgesic activity by inhibiting the experimental pain model where 22.6% (33) showed similar analgesic effect to that of paracetamol (150 mg/kg b.w.). Cassia alata and Gynochtodes retusa ethanol extracts showed the highest analgesic activity (92.73% and 91.87%, respectively). Mimosa pudica and Stenocline inuloides are the most promising species, as they demonstrated potent anti-polymerization (78.08% and 88.84%, respectively) and analgesic (88.44% and 79.71%, respectively) activities. These results show that these plants are good sources of anti-sicking and analgesic compounds that confirm the therapeutic virtues claimed by Malagasy SCD patients and traditional practitioners in the treatment of SCD and its symptoms.