Influence of methylxanthines isolated from Bancha green tea on the pharmacokinetics of sildenafil in rats.

BACKGROUND: Sildenafil is used to treat erectile dysfunction and pulmonary arterial hypertension and is metabolized in the liver mainly by CYP3A4, thus co-administration with drugs or herbal extracts that affect CYP3A4 activity may lead to drug-drug or drug-herb interactions, respectively. The aim of the present study was to evaluate the influence of single and multiple oral doses of methylxanthine fraction, isolated from Bancha green tea leaves on the pharmacokinetics of sildenafil in rats. METHODS: Rats were given sildenafil alone as well as simultaneously with methylxanthines or ketoconazole. The plasma concentrations of sildenafil were measured with high-performance liquid chromatography method with ultraviolet detection. The pharmacokinetic parameters of sildenafil were calculated by non-compartmental analysis. RESULTS: Concomitant use of sildenafil with a single oral dose of methylxanthines resulted in a decrease in Cmax (p > 0.05), AUC0-t (p < 0.05) and AUC0-inf (p < 0.05), while the administration of sildenafil after methylxanthines pretreatment resulted in an increase in Cmax (p < 0.0001), AUC0-t (p < 0.0001) and AUC0-inf (p < 0.001) compared to the sildenafil group. After co-administration of sildenafil and ketoconazole, a significant increase in Cmax, AUC0-t and AUC0-inf was observed in both of the experiments. CONCLUSION: Drug-herb interactions were observed when sildenafil was co-administered with Bancha methylxanthines in rats. Further in vivo studies about the potential drug interactions between sildenafil and methylxanthines, especially caffeine, are needed to clarify mechanisms underlying the observed changes in sildenafil pharmacokinetics.

In vitro antiviral activities of fruit extract from Lycium barbarum and methylxanthines extracted from Pu-erh and Bancha tea leaves.

INTRODUCTION: Based on traditional medicine, many countries use various plant products (fruits, leaves and other plant parts) as food supplements or in the form of tea. The use of these plant sources has been established through the years of use and the proven benefits of their ingredients to improve human health.

Protective Effect of Methylxanthine Fractions Isolated from Bancha Tea Leaves against Doxorubicin-Induced Cardio- and Nephrotoxicities in Rats.

Doxorubicin is an anthracycline antibiotic that is used for the treatment of various types of cancer. However, its clinical usage is limited due to its potential life-threatening adverse effects, such as cardio- and nephrotoxicities. Nonetheless, simultaneous administration of doxorubicin and antioxidants, such as those found in green tea leaves, could reduce cardiac and renal tissue damage caused by oxidative stress. The methylxanthine fraction isolated from Bancha tea leaves were tested in vitro for its antioxidant activity and in vivo for its organoprotective properties against doxorubicin-induced cardio- and nephrotoxicities in a rat model. The in vivo study was conducted on male Wistar rats divided into 6 groups. Methylxanthines were administered at high (5 mg/kg body weight) and low (1 mg/kg body weight) doses, while doxorubicin was administered at a cumulative dose of 20 mg/kg body weight. Serum creatinine, uric acid, and urea concentrations, as well as serum enzyme levels (creatinine kinase (CK), creatinine kinase MB fraction (CK-MB), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH)) and electrolytes (Na+, K+, and Cl-), were analysed. In addition, histological analysis was performed to assess cardiac and renal tissue damage. The concomitant administration of Bancha methylxanthines and doxorubicin showed a dose-dependent reduction in the serum biochemical parameters, indicating a decrease in the cardiac and renal tissue damage caused by the antibiotic. Histological analysis showed that pretreatment with methylxanthines at the dose of 5 mg/kg resulted in an almost normal myocardial structure and a significant decrease in the morphological kidney changes caused by doxorubicin exposure compared with the group that received doxorubicin alone. The putative mechanism is most likely related to a reduction in the oxidative stress caused by doxorubicin.

Isolation, analysis and in vitro assessment of CYP3A4 inhibition by methylxanthines extracted from Pu-erh and Bancha tea leaves.

Methylxanthines, purine alkaloids found in plants, are found in beverages (coffee, tea, cocoa) and foods (chocolate and other cocoa-containing foods) commonly consumed worldwide. Members of this family include caffeine, theophylline and theobromine. Methylxanthines have a variety of pharmacological effects, and caffeine and theophylline are used as pharmaceuticals. Methylxanthines are metabolized in the liver predominantly by the enzyme CYP1A2. Their co-administration with CYP1A2 inhibitors may lead to pharmacokinetic interactions. Little is known about the possible drug interactions between caffeine and substrates of other CYP450 enzymes. In our study, methylxanthine fractions inhibited CYP3A4 in a concentration-dependent manner. Concomitant consumption of green tea with CYP3A4 substrates could increase the possibility of interactions, and this requires further clarification. The inhibition of CYP3A4 is not only due to the presence of catechin derivatives but methylxanthines may also contribute to this effect.

Antioxidant Activity and Antiproliferative Effects of Lycium barbarum's (Goji berry) Fractions on Breast Cancer Cell Lines.

BACKGROUND: Lycium barbarum has gained immense popularity over the past decade because of its antioxidant properties. There are many reports of observed health benefits of juice consumption, including prophylaxis in neoplastic disease and treatment of tumors. MATERIALS AND METHODS: In this study, we isolated three fractions of Lycium barbarum fruits - total water, pectin-free and polysaccharide, and determined their antioxidant activity by ORAC and HORAC assays. We investigated the antiproliferative effects of Lycium barbarum's pectin-free and polysaccharide fraction on three different breast cell lines - MCF-10A (non-tumorigenic epithelial breast cell line), MCF-7 (breast cancer cell line, estrogen, progesterone receptors +, HER2-), and MDA-MB-231 (breast cancer cell line, triple negative), by the MTT dye reduction assay. RESULTS: The Lycium barbarum's pectin-free fraction showed concentration-dependent growth inhibition on the three cell lines, moreover, on cancer cells (MCF- 7 and MDA-MB-231) it was significantly more pronounced. The polysaccharide fraction showed negligible activity on the three cell lines, only the highest concentration (1000 µg/mL), suppressed the proliferation of MCF-7 cells. The combination of pectin-free and polysaccharide fraction on MCF-7 did not show the expected synergistic effect. CONCLUSION: We found a relative correlation between the polyphenolic content of the extracts and the observed effects. The pectin-free extract had the highest content of polyphenols with the best antioxidant and antineoplastic activity against breast cancer cells. Addition of polysaccharide to the pectin-free fraction contributes to its pharmacological activity.