The purpose of this work is to provide a complete study of the influence of operational parameters of the supercritical carbon dioxide assisted extraction (SC CO2E) on yield of wedelolactone from Wedelia calendulacea Less., and to find an optimal combination of factors that maximize the wedelolactone yield. In order to determine the optimal combination of the four factors viz. operating pressure, temperature, modifier concentration and extraction time, a Taguchi experimental design approach was used: four variables (three levels) in L9 orthogonal array. Wedelolactone content was determined using validated HPLC methodology. Optimum extraction conditions were found to be as follows: extraction pressure, 25 MPa; temperature, 40 °C; modifier concentration, 10% and extraction time, 90 min. Optimum extraction conditions demonstrated wedelolactone yield of 8.01 ± 0.34 mg/100 g W. calendulacea Less. Pressure, temperature and time showed significant (p < 0.05) effect on the wedelolactone yield. The supercritical carbon dioxide extraction showed higher selectivity than the conventional Soxhlet assisted extraction method.
The bioavailability of rifampicin (RIF) in a fixed dose combination (FDC) used for the treatment of tuberculosis remains an area of clinical concern and several pharmaceutical alternatives are being explored to overcome this problem. The present study presents a pharmacological approach in which the bioavailability of a drug may be modulated by utilizing the herb-drug synergism. The pharmacokinetic interaction of some herbal products and a pure molecule isolated from Cuminum cyminum with RIF is shown in this paper. An aqueous extract derived from cumin seeds produced a significant enhancement of RIF levels in rat plasma. This activity was found to be due to a flavonoid glycoside, 3',5-dihydroxyflavone 7-O-beta-D-galacturonide 4'-O-beta-D-glucopyranoside (CC-I). CC-I enhanced the Cmax by 35% and AUC by 53% of RIF. The altered bioavailability profile of RIF could be attributed to a permeation enhancing effect of this glycoside.
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