Isolation Of Phenolic Constituents From Portulaca Oleracea L. And Study On Pharmacokinetics Of Oleracein E

In this study, compounds were isolated from Portulaca oleracea L. through various column chromatography including polyamide, silica gel, sephadex LH-20, MCI and Semi-preparative HPLC, and their structures were elucidated based on spectroscopic analysis such as’H NMR, 13C NMR, HSQC and HMBC data.12 phenolic constituents were isolated and identified as vanillin (1), p-hydroxybenzaldehyde (2), protocatechualdehyde (3), p-hydroxybenzoic acid (4), ferulic acid (5), methyl 4-hydroxyphenylacetate (6), isovanillic acid (7), caffeic acid (8), trans-p-hydroxycinnamic acid (9), iseluxine (10), portulacatone (11), and oleracein E (OE,12). Among them,11 was a novel tricyclic alkaloid and compounds 1,2,3,6,10 were isolated from P. oleracea for the first time. Portulacatone (11) and iseluxine (10) showed dose-dependent scavenging activities against DPPH free radical, with EC50 values of 14.63 μM and 9.98 μM, respectively, more potent than the natural antioxidant vitamin C (EC50=20.72μM).Physicochemical property of OE:(1) An HPLV-UV method for the determination of OE in solvent was established, with Inertsil ODS-3 column (4.6x250 mm,5 μm) and precolumn (4.0x3.0 mm,5μm), temperature at 30℃, MeOH-0.1％ formic acid (32:68) as mobile phase, flow rate at 1 mL/min, and wavelength at 287 nm. (2) The solubilities of OE in different solvents at 37℃ from low to high were as following, petroleum ether (insoluble), trichlormethane (36.9976 μg/mL), ethyl acetate (132.4791 μg/mL), n-octanol (410.2657 μg/mL), water (525.0000 μg/mL), acetonitrile (632.0947 μg/mL), n-butanol (1337.3675 μg/mL), ethanol (2573.9049 μg/mL), methanol (5125.1133 μg/mL). The solubilities of OE in different phosphate buffer at 37℃ were as following, pH 2 (487.3359 μg/mL), pH 4 (472.0468 μg/mL), pH 5.8 (483.9740 μg/mL). (3) The effects of pH (2,4,6.8,7.4,8) and temperature (25℃, 37℃,50℃) on stability of OE were studied. It was found that OE was stable in phosphate buffers at pH 2 and pH 4. However, OE was unstable in phosphate buffers at pH 6.8,7.4,8. decomposing with the time going. Higher pH value and higher temperature accelerated the decomposition of OE. (4) logP of OE in octanol/water and octanol/phosphate buffer at pH 2,4,5.8,6.8 were 0.520,0.552,0.575,0.567 and 0.597, respectively.Pharmacokinetics of OE:(1) An HPLV-UV method for the determination of OE in serum were established, with TSKgel ODS-3 column (4.6×250 mm,5μm) and precolumn (4.0x3.0 mm,5μm), temperature at 35℃, MeOH-0.1％ formic acid (28:72) as mobile phase, flow rate at 0.8 mL/min, wavelength at 287 nm, and p-hydroxybenzoic acid as internal standard. Linearity of the calibration curves, recovery rate, precision, specificity, stability, LOD and LOQ of the HPLC method were validated. The method was found to be simple, specific, precise, accurate, and reproducible. (2) The main pharmacokinetic parameters of OE after intragastric administration in rat (10.5 mg/kg body weight) were analyzed by DAS 1.0 program as following:AUC(o-∞)=14.91±6.11μg/mL*min, Cmax=0.31±0.11μg/mL, Tmax=15 min, t1/2z=23.90±9.86min; Pharmacokinetic parameters of OE after intravenous injection in rat (6.4 mg/kg body weight) were as following:AUC(o-∞)=23.20±11.78 μg/mL*min, Cmax=3.14±1.92μg/mL, Tmax=2 min, t1/2z=3.90±0.68 min. The absolute bioavailability of OE after intragastric administration in rat was 39.17%.