Bera Rammohan, Kundu Amit, Sen Tuhinadri, Adhikari Dipan, Karmakar Sanmoy
Division of Pharmacology, Department of Pharmaceutical Technology, Jadavpur University, Kolkata, India.
Department of Botany, Hooghly Mohsin College, Chinsurah, Hooghly, West Bengal, India.
Planta Med. 2016 Apr;82(6):544-50. doi: 10.1055/s-0042-101032. Epub 2016 Feb 25.
Gymnema sylvestre is traditionally used for diabetes mellitus. A literature survey revealed very few reports, particularly on rat liver microsomal stability, caco-2 permeability and efflux concerns and its correlation with the bioavailability of gymnemagenin, an important component of G. sylvestre. Therefore, the objective of our study was to investigate the in vitro rat liver microsomal stability and caco-2 permeability along with the efflux of gymnemagenin and establish a probable correlation of these in vitro findings with pharmacokinetic parameters after oral and intravenous administration in rats.Rat liver microsomal stability studies to estimate the in vitro intrinsic half-life, clearance, and Caco-2 permeability after 21 days of culture to determine the apparent permeability from apical to basal and from basal to apical, and efflux ratio of gymnemagenin were performed using liquid chromatography-tandem mass spectrometry. A sensitive, robust bioanalytical method was validated and successfully applied to determine the plasma exposure of gymnemagenin. In vitro rat liver microsomal stability demonstrated that gymnemagenin metabolizes rapidly with a short apparent and intrinsic half-life (~ 7 min) and high intrinsic clearance, i.e., 190.08 µL/min/mg of microsomes. The results of the Caco-2 study indicated a poor permeability (1.31 × 10(- 6 )cm/sec) with a very high efflux ratio. The pharmacokinetic study revealed poor oral bioavailability (~ 14 %) of gymnemagenin and it was found to have a short half-life and a high clearance in rats. Our in vitro findings indicated low metabolic stability and poor Caco-2 permeability with high efflux, which might have a role in the observed poor oral bioavailability in rats.
匙羹藤传统上用于治疗糖尿病。文献调查显示相关报道极少，尤其是关于大鼠肝微粒体稳定性、Caco-2细胞通透性和外排问题及其与匙羹藤皂苷元（匙羹藤的一种重要成分）生物利用度的相关性。因此，我们研究的目的是研究匙羹藤皂苷元的体外大鼠肝微粒体稳定性、Caco-2细胞通透性以及外排情况，并建立这些体外研究结果与大鼠口服和静脉给药后药代动力学参数之间的可能相关性。使用液相色谱 - 串联质谱法进行大鼠肝微粒体稳定性研究，以估计体外固有半衰期、清除率，并在培养21天后测定Caco-2细胞通透性，以确定从顶端到基底以及从基底到顶端的表观通透性和匙羹藤皂苷元的外排率。一种灵敏、稳健的生物分析方法得到验证，并成功应用于测定匙羹藤皂苷元的血浆暴露量。体外大鼠肝微粒体稳定性研究表明，匙羹藤皂苷元代谢迅速，表观半衰期和固有半衰期较短（约7分钟），固有清除率较高，即190.08 μL/min/mg微粒体。Caco-2细胞研究结果表明通透性较差（1.31×10(-6) cm/sec），外排率非常高。药代动力学研究显示，匙羹藤皂苷元的口服生物利用度较差（约14%），并且在大鼠体内半衰期较短，清除率较高。我们的体外研究结果表明其代谢稳定性低、Caco-2细胞通透性差且外排率高，这可能是导致观察到的大鼠口服生物利用度差的原因。
