Development and characterization of enteric-coated microparticles of biochanin A for their beneficial pharmacological potential in estrogen deficient-hypertension.

Enteric coating of microparticles prevents stomach degradation and enhances oral bioavailability of poorly soluble drugs. Thus, in the present study, enteric-coated microparticle (ECMP) of biochanin A was developed and their pharmacological potential was investigated in hypertensive ovariectomized rats (Ovx-HT). Biochanin A microparticles were prepared by using ionic gelation method and coating was done by ethyl cellulose using coacervation phase separation method. Surface modified microparticles were characterized on the basis of size, entrapment efficiency, polydispersity index, FTIR and zeta potential and percentage of in vitro release. Ovariectomized rats were administered deoxy corticosterone acetate (40 mg/kg, s.c. twice a week for 6 weeks) salt to induce Ovx-HT. Hypertension was assessed in terms of increase in systolic, diastolic, mean arterial blood pressure, lipid peroxidation level, tumor necrosis factor-alpha (TNF-α) level and decrease in serum nitrite and reduced glutathione (GSH) level. The optimized formulation of ECMP has shown significant increase in oral bioavailability assessed by high-performance liquid chromatography. Furthermore, these ECMPs significantly reduced the mean arterial blood pressure, systolic and diastolic blood pressure, reduced lipid peroxidation and TNF-α level and significantly increased the serum nitrite and reduced GSH level in Ovx-HT rats. However, L-NAME significantly prevented the ameliorative effect of ECMP. Thus, it may be concluded that ECMP of biochanin A has shown delayed release capacity, increase in oral bioavailability up to 6 folds than plain biochanin A and exerts antihypertensive effect in ovariectomized rats possibly in an eNOS dependent manner.