Inhibitory effects of tanshinones towards the catalytic activity of UDP-glucuronosyltransferases (UGTs).

CONTENTS: Danshen is a popular herb employed to treat cardiovascular and cerebrovascular diseases worldwide. Danshen-drug interaction has not been well studied. OBJECTIVE: The inhibitory effects of four major tanshinones (tanshinone I, tanshinone IIA, cryptotanshinone, and dihydrotanshinone I) on UDP-glucuronosyltransferases (UGTs) isoforms were determined to better understand the mechanism of danshen-prescription drugs interaction. MATERIALS AND METHODS: In vitro recombinant UGTs-catalyzed 4-methylumbelliferone (4-MU) glucuronidation reaction was employed. Tanshinones (100 µM) was used to perform the initial screening of inhibition capability. High-performance liquid chromatography (HPLC) was used to separate 4-MU and its glucuronide. In vitro-in vivo extrapolation (IV-IVE) was employed to predict in vivo inhibition situation. RESULTS: Cryptotanshinone inhibited UGT1A7 and UGT1A9 with IC50 values of 1.91 ± 0.27 and 0.27 ± 0.03 µM, respectively. Dihydrotanshinone I inhibited UGT1A9-catalyzed 4-MU glucuronidation reaction with the IC50 value of 0.72 ± 0.04 µM. The inhibition of cryptotanshinone towards UGT1A7 and UGT1A9 was best fit to competitive inhibition type, and UGT1A9 was non-competitively inhibited by dihydrotanshinone I. Using in vitro inhibition kinetic parameters (Ki) and in vivo maximum plasma concentration (Cmax) of cryptotanshinone and dihydrotanshinone I, the change of area-under-the-concentration-time curve (AUC) was predicted to be 0.4-4.2%, 3.7-56.3%, and 0.6-6.4% induced by cryptotanshinone and dihydrotanshinone inhibition towards UGT1A7 and UGT1A9, respectively. DISCUSSION AND CONCLUSION: The inhibitory effects of tanshinones towards important UGT isoforms were evaluated in the present study, which provide helpful information for exploring the mechanism of danshen-clinical drugs interaction.

Inhibition of UDP-Glucuronosyltransferases (UGTs) Activity by constituents of Schisandra chinensis.

Structure-activity relationship for the inhibition of Schisandra chinensis's ingredients toward (Uridine-Diphosphate) UDP-glucuronosyltransferases (UGTs) activity was performed in the present study. In vitro incubation system was employed to screen the inhibition capability of S. chinensis's ingredients, and in silico molecular docking method was carried out to explain possible mechanisms. At 100 µM of compounds, the activity of UGTs was inhibited by less than 90% by schisandrol A, schisandrol B, schisandrin, schisandrin C, schisantherin A, gomisin D, and gomisin G. Schisandrin A exerted strong inhibition toward UGT1A1 and UGT1A3, with the residual activity to be 7.9% and 0% of control activity. Schisanhenol exhibited strong inhibition toward UGT2B7, with the residual activity to be 7.9% of control activity. Gomisin J of 100 µM inhibited 91.8% and 93.1% of activity of UGT1A1 and UGT1A9, respectively. Molecular docking prediction indicated different hydrogen bonds interaction resulted in the different inhibition potential induced by subtle structure alteration among schisandrin A, schisandrin, and schisandrin C toward UGT1A1 and UGT1A3: schisandrin A > schisandrin > schisandrin C. The detailed inhibition kinetic evaluation showed the strong inhibition of gomisin J toward UGT1A9 with the inhibition kinetic parameter (Ki ) to be 0.7 µM. Based on the concentrations of gomisin J in the plasma of the rats given with S. chinensis, high herb-drug interaction existed between S. chinensis and drugs mainly undergoing UGT1A9-mediated metabolism. In conclusion, in silico-in vitro method was used to give the inhibition information and possible inhibition mechanism for S. chinensis's components toward UGTs, which guide the clinical application of S. chinensis.

Chirality Influence of Zaltoprofen Towards UDP-Glucuronosyltransferases (UGTs) Inhibition Potential.

Zaltoprofen (ZLT) is a nonsteroidal antiinflammation drug, and has been clinically employed to treat rheumatoid arthritis, osteoarthritis, and other chronic inflammatory pain conditions. The present study aims to investigate the chirality influence of zaltoprofen towards the inhibition potential towards UDP-glucuronosyltransferases (UGTs) isoforms. In vitro a recombinant UGT isoforms-catalyzed 4-methylumbelliferone (4-MU) glucuronidation incubation system was employed to investigate the inhibition of (R)-zaltoprofen and (S)-zaltoprofen towards UGT isoforms. The inhibition difference capability was observed for the inhibition of (R)-zaltoprofen and (S)-zaltoprofen towards UGT1A8 and UGT2B7, but not for other tested UGT isoforms. (R)-zaltoprofen exhibited noncompetitive inhibition towards UGT1A8 and competitive inhibition towards UGT2B7. The inhibition kinetic parameters were calculated to be 35.3 µM and 19.2 µM for UGT1A8 and UGT2B7. (R)-zaltoprofen and (S)-zaltoprofen exhibited a different inhibition type towards UGT1A7. Based on the reported maximum plasma concentration of (R)-zaltoprofen in vivo, a high drug-drug interaction between (R)-zaltoprofen and the drugs mainly undergoing UGT1A7, UGT1A8, and UGT2B7-catalyzed glucuronidation was indicated.

Ultrastructural observation on pulmonary fibrosis in E9 rats treated with compound Carapax trionycis formula.

OBJECTIVE: To investigate ultrastructural changes in pulmonary tissue of a rat model of pulmonary fibrosis following treatment with compound Carapax trionycis (C. trionycis; Biejia in Chinese) formula. METHODS: Sixty male Sprague-Dawley rats were randomly divided into four groups (n=15): compound C. trionycis formula high-, middle-, and low-dose groups as well as model group. Pulmonary fibrosis was induced by bleomycin. Five rats from each group were sacrificed on day 7, 14 and 28 of the drug treatment, respectively. The pulmonary tissue was harvested followed by hematoxylin-eosin staining and subsequent transmission electron microscopy. The Szapiel's method was used to assess the degree of alveolitis and pulmonary fibrosis. RESULTS: Compared with the model group, the compound C. trionycis formula groups had slighter pulmonary alveolitis after the 7-day treatment and also had alleviated alveolar inflammation and pulmonary fibrosis after the 14-day treatment. After the 28-day treatment, the compound C. trionycis formula groups showed deposition of a small amount of fibrous tissue and lesions occupying less than 21% of the whole lung area, while the model group showed focal or diffuse fibrous deposition, narrow alveolar cavity, disordered lung structure, and lesions in larger than 51% of the whole lung area. CONCLUSIONS: The compound C. trionycis formula can inhibit the proliferation of collagen fibers and resist pulmonary fibrosis.