HPLC characterization, acute and sub-acute toxicity evaluation of bark extract of Rhizophora mucronata in Swiss Albino mice

Abstract Aim Rhizophora mucronata, commonly called as ‘red mangrove’ grows in the tropical and sub-tropical regions and on the sheltered shores. The bioactive compounds from the plant have been used in the treatment of wide range of diseases. Though the beneficial effects have been reported, the safety and toxicological studies are not carried out. Hence, major bioactives have been identified by HPLC and then acute and sub-acute toxicity studies of (BERM) in Swiss Albino mice have been carried out. Main methods HPLC fingerprinting was carried out of BERM for the characterization of bioactives. BERM as a single dose was given orally at 800, 1600 mg/kg and 3200 mg/kg by a stainless steel cannula to the mice. Then the mice were observed for 14 days for mortality and behavioural changes. Food, water intake and body weight changes were also observed throughout the study period. On the fifteenth day, the mice were anesthetized with isofluorane and blood was withdrawn for haematological and biochemical analysis. The animals were sacrificed by overdose of isofluorane and organs such as liver, kidney, lungs and spleen were dissected out for histopathological analysis. There was no mortality of the mice even in 3200 mg/kg dose, stating that the oral LD50 of BERM is more than 5000 mg/kg. In terms of Sub-acute toxicity, for a period of 28 days repeated dose of 400 mg/kg and 800 mg/kg as an optimum dose and a control group was kept with only distilled water at 5 ml/kg against the treated groups. On 29th day, the mice from all groups were sacrificed and blood was withdrawn and organs such as liver, kidney, lungs and spleen were dissected out for the assessment of internal tissues, wherein no abnormalities were observed in the treatment groups as compared to the control. The blood parameters, biochemical analysis of the treated groups were well within the range, histopathological confirmed the findings wherein the organs viz, liver, kidneys, lungs and spleen possessed normal architecture. Key findings Based on HPLC results, prominent 5 major compounds viz: Diadzein, Epicatechin, Hesperidin, Diosmin and Quercitrin respectively were identified. Isolated changes observed in the haematological, biochemical and histopathological studies were not dose related and showed the safety of the bark extract. Similarly, the sub-acute toxicity of BERM has been conducted for 28 days, wherein repeated dose of 400 mg/kg and 800 mg/kg and control group was given orally. There were no abnormalities found both in external and internal parameters. Significance Based on the study it is concluded that the bark extract of Rhizophora mucronata (BERM) is safe at 1000 mg/kg or less on repeated dosage can be considered as a safe dose for pharmacological efficacy studies.