Extraction optimization, structural characterization and potential alleviation of hyperuricemia by flavone glycosides from celery seeds.

Celery seeds are commonly used as condiments and in herbal teas with high medicinal value. In the present study, we investigated the contents of extracts derived under different extraction conditions and determined the optimal conditions for only extracting flavone glycosides from celery seeds. The compositional analysis identified three primary flavone glycosides in the ethanolic extract, and apiin, graveobioside A, and graveobioside B were isolated. Apigenin, luteolin, and chrsyeriol were obtained by the acid hydrolysis of flavone glycosides under high-temperature conditions. Here we investigated the inhibitory activity of apigenin and apiin on xanthine oxidase by reducing the rate of oxidative cytochrome C and found that both apigenin and apiin reduced cytochrome C production, except for low concentrations of apiin. In vivo analysis with hyperuricemia mice and rats showed that apiin had excellent uric acid-lowering effects and high dose-dependence, while apigenin was relatively slightly uric acid-lowering. In addition, the flavone glycoside extracts from celery seeds exhibited similar effects of reducing uric acid with apiin. Surprisingly, in hyperuricemia rats, the uric acid-lowering effects of high-dose apiin and flavone glycoside extracts were almost comparable to that of allopurinol. Besides, our experimental results showed that apigenin could improve uric acid clearance by increasing the glomerular filtration capacity, which was reflected in reducing the renal function parameters SUN and SCr; also, apiin showed better results. This study also showed that celery seeds have a unique medicinal value in treating hyperuricemia and that the flavone glycoside extracts from celery seeds can be developed as medicine for hyperuricemia.

[Simultaneous determination of allopurinol, probenecid, benzbromarone in dietary supplements by ultra high performance liquid chromatography-tandem mass spectrometry].

A method based on QuEChERS purification was developed for the simultaneous determination of allopurinol, probenecid and benzbromarone in anti-gout dietary supplements by ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted by acetonitrile mixed with 0.1% (v/v) ammonium hydroxide, and the extracts were purified using primary secondary amine (PSA) and C18 adsorbents. The samples were separated on a C18 chromatographic column with the gradient elution of 0.1% (v/v) formic acid aqueous solution and methanol as mobile phases. The analytes were detected by a electrospray ionization source in the positive or negative ion mode and the multiple reaction monitoring mode. The results showed that the limits of detection of allopurinol, probenecid and benzbromarone were 5, 25 and 25 µg/kg, and the limits of quantification were 17, 80 and 80 µg/kg. The average spiked recoveries of the three chemical drugs in dietary supplements were in the range of 76.8%-116.6% with the relative standard deviations of 2.7%-14.6%. The proposed method was applied for the analysis of 68 dietary supplements, and allopurinol was detected in one of them. This method is simple and sensitive, and can be used for the determination of the allopurinol, probenecid and benzbromarone in anti-gout dietary supplements.

Improved bioautographic assay on TLC layers for qualitative and quantitative estimation of xanthine oxidase inhibitors and superoxide scavengers.

A new agar-free bioautographic assay for xanthine oxidase (XO) inhibitors and superoxide scavengers on TLC layers was developed and validated. Compared to the first version of TLC bioautographic agar overlay method, our bioautographic assay greatly improved the sensitivity and quantification ability. The limit of detection (LOD) of this assay was 0.017ng for allopurinol. Quantitative estimation of XO inhibitors and superoxide scavengers was achieved by densitometry scanning, expressed as allopurinol equivalents in millimoles on a per sample weight basis. This assay has acceptable accuracy (95.37-99.23%), intra-day and inter-day precisions (RSD, 2.56-6.69%), as well as intra-plate and inter-plate precisions (RSD, 2.93-9.62%). Six pure compounds and three herbal extracts were evaluated for their potential XO inhibitory and superoxide scavenging activity by this bioautographic assay on TLC layers. Four active components were separated, located and identified in Astragalus membranaceus var. mongholicus extract by the bioautographic assay after TLC separation. The developed method is rapid, simple, sensitive and stable for screening and estimation of the potential XO inhibitors and superoxide scavengers.

Flow injection determination of xanthine oxidase inhibitory activity and its application to food samples.

The enzyme xanthine oxidase (XOD) has been recognized as a key enzyme causing oxidative injury to tissues by ischemia-reperfusion. For this reason, XOD inhibitor, which effectively suppresses this enzyme, plays an important role in the inhibition of many diseases related to reactive oxygen species (ROS). In order to screen XOD inhibitors rapidly and conveniently, a novel assay using flow injection analysis (FIA) was proposed in the present investigation. To optimize the practical FIA system, we studied the effect of the reagent concentrations and the flow condition on the enzymatic reaction, and then selected the optimum condition as follows: 200-mU/ml XOD concentration, 0.5-mM xanthine concentration, 0.5-ml/min flow rate, and 2-m mixing coil length. Under this condition, a typical XOD inhibitor quercetin was determined in the concentration range 0.1 - 1.5 mM at a sampling frequency of 10 samples/h. Using the optimized FIA method, we determined the XOD inhibitory activity of some food samples: onions, apples and teas, which are the high sources of flavonoids known as the potential XOD inhibitors. Among these samples, tea leaves showed the highest activity, the second was onions and the lowest was apples. Based on the result of the assay, not only quercetin, but also other components in investigated samples, contributed to the XOD inhibitory activity.