Relative Astringent and Hemostatic Activities of Methanolic Leaf Extracts of Croton Megalocarpus Hutch and Lantana Camara Linn.
Muindi, Hezron Mutisya
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Natural hemostatic physiology is sufficient for the management of mild to moderate bleeding episodes. Severe bleeding may overwhelm the human coagulation system. Astringent agents’ localized action on blood vessels during primary hemostasis leads to vasoconstriction and control of blood loss. Hemostatic agents act on coagulation factors within secondary hemostasis by shortening blood clotting. Conventional hemostatic and astringent agents are associated with tissue damage, discoloration of bone, risks of viral transmission and allergic reactions. Croton megalocarpus Hutch and Lantana camara Linn plants are used for bleeding control in Makueni County in South Eastern Kenya. In the current study, the effects of methanolic extracts from the two plants on mice plasma coagulation time and also on hemoglobin precipitation were investigated. Air-dried leaves were milled, extracted in absolute methanol, concentrated and dried to powder. A qualitative phytochemical evaluation of extracts was conducted. Blood samples were collected from 55 laboratory-bred mice, then plasma was prepared. Hemoglobin from hemolyzed mice blood was mixed with plant extract solutions at 0.25, 0.5 and 1 mg/ml concentrations and the residual protein was determined spectrophotometrically. Relative astringency was calculated following comparison of the optical density (OD) of the extract-hemoglobin preparation with the corresponding concentration of an external Tannic acid standard. In evaluation of hemostatic activity, plant extract solutions at 0.25, 0.5 and 1 mg/ml concentrations were mixed with 55 mice plasma samples before prothrombin time (PT) and active partial thromboplastin time (aPTT) tests were assayed. The data was analyzed statistically using one-way ANOVA. Preliminary qualitative phytochemical analysis of C. megalocarpus (H.) and L. camara (L.) extracts contained tannins, phenols, cardiac glycosides, terpenoids, reducing sugars and carbohydrates. Additionally, C. megalocarpus (H.) contained steroids and flavonoids, while L. camara (L.) leaf extract was found to have saponins. Methanolic leaf extracts of C. megalocarpus (H.), L. camara (L.) and the blend were found to have hemoglobin precipitating activity compared to the normal control where the relative astringency effects were concentration dependent. Methanolic extracts of C. megalocarpus (H.), L. camara (L.) and the blend significantly reduced aPTT and PT in a dosage dependent pattern, indicating hemostatic activities involving the extrinsic, intrinsic and common pathways of blood coagulation. Inhibition activity affecting relative astringency and prothrombin time was detected in the blended extract. The hemoglobin precipitating properties of C. megalocarpus (H.) and L. camara (L.) extracts are linked to the activity of tannins, flavonoids, and phenols. A significant reduction in plasma aPTT and PT coagulation time is associated with the activity of tannins, phenols, flavonoids, and saponins. The extracts of C. megalocarpus (H.) and L. camara (L.) caused significant hemoglobin precipitation and reduced plasma coagulation time. Further studies on isolated compounds from both plants for effects on plasma coagulation and bleeding time are recommended.