Search

Eclipta alba (Bhringraj) in ayurveda has been widely used as a traditional medicine for its multi-therapeutic properties for ages. Luteolin (LTL), wedelolactone (WDL) and apigenin (APG) are the three main bioactive phytochemicals present in Eclipta alba extract. However there was a lack of sensitive bioanalytical method for the pharmacokinetics of these free compounds in plasma which majorly contributes for their activities after oral administration of Eclipta alba. The present study aims to develop a sensitive, rapid and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous estimation of mice plasma concentrations of LTL, WDL and APG using quercetin as an internal standard for the pharmacokinetic analysis. Analytes were separated on Phenomenex Luna C18 (150 × 4.6 mm, 3.0 μm) column with mobile phase containing methanol: acetonitrile (90: 10, v/v) and 0.1% formic acid in 10 mM ammonium formate buffer in the ratio of 70: 30 (v/v) in isocratic mode. Liquid-liquid extraction was optimized using Hansen solubility parameters and diethyl ether finalized as an extraction solvent for the recovery ranging from 61 to 76% for all analytes in mice plasma. The validated method has an accuracy and precision over the linearity range of 0.1-200 ng/mL with a correlation coefficient (r 2 ) of ≥0.997. The intra and inter-day assay accuracy was between 98.17 and 107% and 95.83-107.89% respectively and the intra and inter day assay precision ranged from 0.37-6.05% and 1.85-10.76%, respectively for all the analytes. This validated method can be used for future clinical investigation studies of Eclipta alba extracts., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Luteolin (3',4',5,7-tetrahydroxyflavone) and apigenin (4',5,7-trihydroxyflavone) are two common flavones and major bioactive components in Flos Chrysanthemi extract (FCE). Although FCE contains approximately equal amounts of luteolin (6.5%, w/w) and apigenin (5.4%, w/w), luteolin showed a much lower exposure than apigenin when FCE was orally administered to rats. The aim of the present study is to elucidate the mechanisms that caused the pharmacokinetic difference between luteolin and apigenin in rats. The results of an in situ rat intestinal single-pass perfusion model showed that the permeability of luteolin (k(a), 7.96×10⁻² min⁻¹ and P(eff), 4.87×10⁻³ cm/min) was about 50% that of apigenin (k(a), 18.5×10⁻² min⁻¹ and P(eff), 10.8×10⁻³ cm/min), which agreed with the observation that oral bioavailability of luteolin (30.4%) from FCE was significantly lower than that of apigenin (51.1%). On the other hand, luteolin was much more unstable than apigenin during the incubation with primary rat hepatocytes, and methylated metabolites of luteolin were detected after incubation. In addition, further metabolism of methylated luteolin also contributed to the faster elimination of luteolin. In conclusion, luteolin and apigenin are very similar in structure, however, one-hydroxyl difference gives them different characteristics in absorption and metabolism, which results in much lower exposure of luteolin than apigenin when FCE is orally administered to rats.

A specific and accurate high-performance liquid chromatographic method has been developed and validated for the simultaneous determination of luteolin and apigenin in the plasma of dog. The sample was treated with 6.0% perchloric acid to precipitate the protein. Luteolin and apigenin were extracted with ethyl acetate. The organic layer separated was dried and reconstituted in the mobile phase. The HPLC separation was performed on C18 column and the UV detector was set at 350 nm. The standard curve for luteolin and apigenin in plasma were linear over the range of 38.5-4350 and 16.5-1860 ng/ml, with the correlation coefficients 0.9996 and 0.9999, respectively. The assay recoveries for luteolin and apigenin ranged from 102.7 to 104.5% and 93.8-101.8%, respectively. The intra- and inter-day precisions (R.S.D.) for luteolin and apigenin were all less than 7.9%. The sample was stable within 24 h at 4 degrees C storage, 30 days at -20 degrees C storage, and undergoing four freeze-thaw-assay cycles. The limits of detection (LOD) of luteolin and apigenin were 1.82 and 1.94 ng/ml, while the limits of quantification (LOQ) were 7.84 and 6.29 ng/ml, respectively. The method developed was applied successfully to study pharmacokinetics of the effective composition (luteolin) of Chrysanthemum morifolium extract in dogs after single dose of oral administration.