Platelet augmentation activity of mature leaf juice of Sri Lankan wild type cultivar of Carica papaya L: Insights into potential cellular mechanisms.

ETHNOPHARMACOLOGICAL RELEVANCE: Carica papaya L., a common fruit crop of the family Caricaceae and its leaf juice/extract is a traditionally commended preparation against dengue and other thrombocytopenic diseases by many Asian countries. AIM OF THE STUDY: The present study posits the potential cellular mechanisms of platelet augmentation activity of mature leaf juice of Sri Lankan wild-type Carica papaya. MATERIALS AND METHODS: C. papaya leaf juice prepared from different cultivar types, maturity of the leaf, agro-climatic region, and preparation methods were orally administered to hydroxyurea-induced thrombocytopenic rats at 0.72 ml/100 g BW dosage to investigate the most potent platelet increasing preparation. The papaya juice doses; low dose (LD-0.18 ml/100 g BW), human equivalent dose (HED-0.36 ml/100 g BW), and high dose (HD-0.72 ml/100 g BW), were administered to thrombocytopenic rats (N = 6/group) daily for three consecutive days and post-treatment plasma levels of interleukin 6 (IL-6), thrombopoietin (TPO), and platelet-activating factor (PAF) were quantified using specific rat ELISA kits. The mature leaf juice of C. papaya induced IL-6 secretion from bone marrow cell (BMC) cultures was quantified using ELISA. The ability of papaya juice to protect the platelet membrane, from the damage caused by the lytic agent was analyzed in vitro using the lactate dehydrogenase (LDH) assay. The effect of the mature leaf juice of C. papaya on secondary hemostasis was investigated using blood coagulation and clot hydrolyzing activity. RESULTS: The comparative analysis revealed that the platelet increasing activity of C. papaya leaf did not significantly differ among different types of cultivar, maturity of the leaf, agro-climatic regions and preparation methods (p > 0.05). Both TPO and PAF levels in thrombocytopenic rats diminished when treated with all three doses of the mature leaf juice of C. papaya (p < 0.05), yet IL-6 plasma level was unaltered (p > 0.05). Nevertheless, ex vivo treatment of the mature leaf juice of C. papaya had significantly enhanced IL-6 levels of rat BMC cultures (p < 0.05). Pre-treatment of platelets with the mature leaf juice of C. papaya at different concentrations significantly inhibited LDH leakage from platelets and may have reduced the membrane damage caused by the lytic agent (p < 0.05). Treatment of mature leaf juice of C. papaya also significantly reduced blood clotting time through the extrinsic pathway of the blood coagulation cascade (p < 0.05). Further, prolonged incubation of the plasma clot with different concentrations of the papaya leaf juice revealed dose-dependent hydrolysis of the blood clot, indicating fibrinolysis activity. CONCLUSIONS: The current study exceeded the traditional medicinal claims, and scientifically affirmed the platelet augmentation activity of mature leaf juice of C. papaya. The mechanistic rationale tested herein explicated that the platelet augmentation activity of the papaya leaf juice can be partially attributed to the stimulation of bone marrow megakaryocytes via modulating thrombopoietic cytokines TPO and IL-6, and by inhibiting the secretion of PAF, while reducing the peripheral platelet destruction by stabilizing the platelet membrane. Further, mature leaf juice of C. papaya imparted both pro-coagulation and fibrinolysis activity of secondary hemostasis endorsing its potential against thrombocytopenia.

Effects of Sri Lankan black tea (Camellia sinensis L.) on pregnancy of rats.

The aim of this study was to demonstrate the potential effects of black tea brew of Camellia sinensis using Sri Lankan high grown dust grade no. 1 tea on pregnancy outcome of rats when exposed during early (days 1-7), mid (days 8-14) and late (days 15-21) pregnancy of rats. Different doses of black tea brew (mg/ml/day) was orally administered daily during this period to separate groups of rats (n = 6/group): 84 (equivalent to 1.5 cups), 167 (3 cups), 501 (9 cups), and 1336 (24 cups). The results showed that black tea brew did not significantly (P > 0.05) change the pregnancy outcome (in terms of quantal pregnancy, number of uterine implants, number of viable implants, implantation index, pre-implantation loss, post-implantation loss, gestation index, number of pups born, litter index, live birth index and viability index) and pre- (in terms of length of the implants/foetus, gestation length, cranial length, cranial diameter and tail length of pups) and postnatal (in terms of time taken to open eyes, eruption of incisors and appearance of fur) development. Furthermore, black tea brew did not induce gross morphological birth abnormalities. If the results are applicable to women, it is concluded that even heavy consumption of black tea brew during pregnancy may not be harmful for pregnancy outcome.