Leonotis leonurus: the anticoagulant and antidiabetic activity of Leonotis leonurus

Commercial marrubiin, aqueous and organic extracts of Leonotis leonurus were tested in vitro for their anticoagulant and antiplatelet activities. The aqueous extract inhibited platelet aggregation by 69.5 percent (100 μg/mL), while the organic extract (100 μg/mL) and marrubiin (5 μg/mL) showed 92.5 percent and 91.6 percent inhibition, respectively, by inhibiting the binding of fibrinogen to glycoprotein IIb/IIIa receptor in a concentration dependent manner. The extracts significantly prolonged activated partial thromboplastin time compared to untreated plasma controls. Fibrin and D-Dimer formation were drastically decreased. The extracts and marrubiin concentration-dependently inhibited calcium mobilization induced by collagen and thrombin. The formation of thromboxane A2 was also significantly reduced by both the extracts and marrubiin. Protein secretion and platelet adhesion were significantly reduced by both the extracts and marrubiin. The organic extract and marrubiin showed a more pronounced effect than the aqueous extracts in all the in vitro assays. The ex-vivo animal model confirmed the results obtained in vitro. Similar to the in vitro studies, activated partial thromboplastin time clotting time was prolonged by marrubiin and the number of aggregated platelets were significantly reduced relative to aspirin. The findings reflect that marrubiin largely contributes to the organic extract's anticoagulant and antiplatelet effect in vitro. INS-1 cells were cultured under normo- and hyperglycaemic conditions. Marrubiin and the two Leonotis leonurus extracts were screened for anti-diabetic activity in vitro. The stimulatory index of INS-1 cells cultured under hyperglycaemic conditions was significantly increased by 60 percent and 61 percent (p<0.01; n=5) in cells exposed to the organic extract (10 μg/mL) and marrubiin (500 ng/mL), respectively, relative to the normoglycaemic conditions. The gene expression of insulin was significantly increased by 76.5 and 71 percent, and of glucose transporter-2 by 93 and 92.5 percent for marrubiin and the organic extract, respectively, under the same conditions stipulated above (p<0.01; n=4). The extract and marrubiin similarly showed an increase in respiratory rate under hyperglycaemic conditions. Marrubiin increased insulin secretion, HDL-cholesterol, while it decreased total cholesterol, LDL-cholesterol and the atherogenic index in the in vivo rat model

In vitro testing to investigate the anticoagulant/antithrombotic and antidiabetic biological activity of Leonotis Leonurus

The rising costs of prescription drugs in the maintenance of personal health and wellbeing have increased the interest in medicinal plants. The World Health Organization estimates that 65 percent-80 percent of the world’s population use traditional medicine as their primary form of health care. In this project the focus has been on the use of Leonotis leonurus extracts as a traditional medicine. The major chemical constituent of this plant is marrubiin, which is a diterpenoid labdane lactone formed from a precursor called premarrubiin. Aqueous and acetone extract (AL and OL extract, respectively) of this plant has been found to have an antithrombotic effect, with IC50 values of 3mg/ml and 6mg/ml, respectively. The extracts also have an effect on fibrinolysis, where the lysis time was decreased by more than 50 percent by the organic extract and standard marrubiin. In whole blood ADP-induced platelet aggregation, the organic extract inhibited aggregation by 68 percent at a final concentration of 138μg/ml (equivalent to 7.2μg/ml marrubiin). Marrubiin has also been screened for antithrombotic/anticoagulant activity; no antithrombotic activity has been observed but it increased the rate of fibrinolysis, by decreasing lysis time by 64 percent and also decreasing fibrin formation. From these findings it can be concluded that marrubiin has a fibrinolytic effect and antiplatelet aggregation effect. In the diabetic studies, in hyperglycemic condition, the OL (10μg/ml) extract and standard marrubiin significantly increased insulin secretion by 200 percent (2-fold) and 400 percent (4-fold), respectively, with respect to the control. The OL extract and standard marrubiin stimulated the release of insulin, the stimulatory index was significantly increased by 450 percent (4.5-fold) and 500 percent (5-fold), respectively, with respect to the control. In the apoptotic studies, in the normoglycemic and hyperglycemic conditions, the OL extract decreased the occurrence of apoptosis, in a dose-dependent manner, with the lower concentrations inducing apoptosis significantly higher than the relevant controls. Standard marrubiin did not have an effect on apoptosis in hyperglycemic condition, but it decreased the occurrence of apoptosis by 200 percent (2-fold) under normoglycemic conditions. The OL extract increased proliferation by 148 percent (1.48- fold) and 155 percent (1.55-fold) in normoglycemic and hyperglycemic conditions, respectively. The same effect was observed for standard marrubiin, where, proliferation was increased by 180 percent (1.8-fold) and 200 percent (2.0-fold) in normoglycemic and hyperglycemic conditions, respectively. RT-PCR displayed that standard marrubiin inhibited the expression of insulin by 50 percent under normoglycemic conditions

Antithrombotic/anticoagulant and anticancer activities of selected medicinal plants from South Africa

Nine plants available in the Eastern Cape Province of South Africa were tested for antithrombotic and/or anticoagulant activity. Organic (methanol) and aqueous (distilled water) extractions were performed on the various plant parts. The thrombin assay and clotting time assays (thrombin-induced and CaCl 2 -induced) were utilised. Several extracts displayed activity, but in most cases this was due to the presence of tannins. Only the aqueous extracts displayed activity after tannin removal. The Sutherlandia frutescens leaf extract displayed antithrombotic activity, with an IC 50 value of 2.17 mg/ml. Gloriosa superba and Zantedeschia aethiopica leaf extracts displayed anticoagulant properties by inhibiting thrombin-induced clotting, with IC 50 values of 2.97 and 3.05 mg/ml, respectively. The Leonotis leonurus root extract was found to decrease the CaCl 2 -induced clotting time by 50% at 8.88 mg/ml. A decrease in this value accompanied by a decrease in fibrin formation was preferable for the CaCl 2 -induced assay, since decreased fibrin formation may have a role in the prevention of cancer metastasis. As tannins were found to contribute minimally to the anticoagulant effect of L. leonurus, the cytotoxicity potential of the extracts of this species against five cell lines was determined. Only the organic extract yielded significant cytotoxity

Antithrombotic/anticoagulant and anticancer activities of selected medicinal plants from South Africa

Nine plants available in the Eastern Cape Province of South Africa were tested for antithrombotic and/or anticoagulant activity. Organic (methanol) and aqueous (distilled water) extractions were performed on the various plant parts. The thrombin assay and clotting time assays (thrombin-induced and CaCl 2 -induced) were utilised. Several extracts displayed activity, but in most cases this was due to the presence of tannins. Only the aqueous extracts displayed activity after tannin removal. The Sutherlandia frutescens leaf extract displayed antithrombotic activity, with an IC 50 value of 2.17 mg/ml. Gloriosa superba and Zantedeschia aethiopica leaf extracts displayed anticoagulant properties by inhibiting thrombin-induced clotting, with IC 50 values of 2.97 and 3.05 mg/ml, respectively. The Leonotis leonurus root extract was found to decrease the CaCl 2 -induced clotting time by 50% at 8.88 mg/ml. A decrease in this value accompanied by a decrease in fibrin formation was preferable for the CaCl 2 -induced assay, since decreased fibrin formation may have a role in the prevention of cancer metastasis. As tannins were found to contribute minimally to the anticoagulant effect of L. leonurus, the cytotoxicity potential of the extracts of this species against five cell lines was determined. Only the organic extract yielded significant cytotoxity