Identification of Escherichia coli β-glucuronidase inhibitors from Polygonum cuspidatum Siebold & Zucc

Abstract Gut bacterial β-glucuronidase (GUS) can reactivate xenobiotics that exert enterohepatic circulation- triggered gastrointestinal tract toxicity. GUS inhibitors can alleviate drug-induced enteropathy and improve treatment outcomes. We evaluated the inhibitory effect of Polygonum cuspidatum Siebold & Zucc. and its major constituents against Escherichia coli GUS (EcGUS), and characterized the inhibitory mechanism of each of the components. Trans-resveratrol 4'-O-β-D-glucopyranoside (HZ-1) and (-)-epicatechin gallate (HZ-2) isolated from P. cuspidatum were identified as the key components and potent inhibitors. These two components displayed strong to moderate inhibitory effects on EcGUS, with Ki values of 9.95 and 1.95 μM, respectively. Results from molecular docking indicated that HZ-1 and HZ-2 could interact with the key residues Asp163, Ser360, Ile 363, Glu413, Glu504, and Lys 568 of EcGUS via hydrogen bonding. Our findings demonstrate the inhibitory effect of P. cuspidatum and its two components on EcGUS, which supported the further evaluation and development of P. cuspidatum and its two active components as novel candidates for alleviating drug-induced damage in the mammalian gut.

Simultaneous Determination of 8 Non-anthraquinone Constituents in Rheum palmatum by HPLC / 中国药房

OBJECTIVE： To establish a method for simultaneous determination of 8 non-anthraquinone constituents in Rheum palmatum. METHODS： HPLC method was adopted. The determination was performed on Symmetry C18 column with mobile phase consisted of methanol-0.1％ phosphoric acid （gradient elution） at the flow rate of 1.0 mL/min. The column temperature was 30 ℃ and detection wavelength was 280 nm. Sample size was 30 μL. RESULTS： The linear range of gallic acid， catechin， epicatechin， resveratrol 4′-O-glucopyranoside， epicatechin gallate， resveratrol 4′-O-β-D-（6″-O-galloyl）-glucopyranoside， sennoside A， 4′-hydroxyphenyl-2-butanone-4′-O-β-D-（2″-O-galloyl-6″-O-p-hydroxy cinnamyl）-glucopyranoside were 6.16-2 464 ng（r＝0.999 9）， 37.4-14 960 ng（r＝0.999 9）， 7.635-3 054 ng（r＝0.999 7）， 7.63-3 052 ng（r＝0.999 9）， 8.32-3 328 ng（r＝0.999 9）， 11.5-4 600 ng（r＝0.999 9）， 16.08-6 432 ng（r＝0.999 9）， 29.3-11 720 ng（r＝0.999 9）， respectively. The limits of quantitation were 3.48， 4.30， 6.40， 4.40， 3.39， 2.87， 8.40 and 4.95 ng， respectively. The limits of detection were 2.32， 2.58， 2.40， 2.64， 2.26， 1.23， 4.20， 2.97 ng， respectively. RSDs of precision， stability and reproducibility tests were all lower than 5％. Recoveries were 94.32％- 100.54％（RSD＝2.78％，n＝6）， 91.15％-99.36％（RSD＝3.72％，n＝6）， 92.16％-98.04％（RSD＝2.39％，n＝6）， 93.41％-100.73％（RSD＝3.17％，n＝6）， 93.89％-98.40％（RSD＝1.99％，n＝6）， 92.61％-101.74％（RSD＝3.71％，n＝6）， 92.66％-103.40％（RSD＝3.76％，n＝6）， 95.45％-102.70％（RSD＝3.06％，n＝6）， respectively. CONCLUSIONS： The established method is simple， accurate and specific， and can be used for the simultaneous determination of 8 non-anthraquinone constituents in R. palmatum.

Screening of anti-oxidant components of Gongcheng Tea by HPLC-UV-FLD and micro-injection systems / 中草药

Objective: A high performance liquid chromatography-ultraviolet-fluorescence (HPLC-UV-FLD) derivative system was established and the anti-oxidant activity of the extract of Gongcheng Tea was preliminarily evaluated by using a micro-injector imaging system combined with a fluorescent probe. Methods: Hydrogen peroxide assay and hydroxyl radical scavenging ability experiments were carried out on the anti-oxidant activity of Gongcheng Tea. The anti-oxidant components of Gongcheng Tea were screened by HPLC-UV-FLD post column derivation system and analyzed by an ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF MS). At the same time, the hydrogen peroxide scavenging activity of tea and active components were tested by a micro-injector imaging system combined with a hydrogen peroxide fluorescent probe (NBCD) in living Drosophila melanogaster. Results: The method was simple and rapid, and three main anti-oxidant compounds, epigallocatechin, epigallocatechin gallate, and epicatechin gallate were found in Gongcheng Tea. And it was found that they could significantly reduce the level of hydrogen peroxide in D. melanogaster. Conclusion: It laid a material basis for the further study of the anti-oxidant activity of Gongcheng Tea, and provided a reference for the screening of anti-oxidants in natural products.

Determination of six catechins in Xinnaojian Capsules (Tablets) by QAMS / 中成药

AIM To establish a quantitative analysis of multi-components by single marker(QAMS) method for the content determination of six catechins in Xinnaojian Capsules (Tablets) (tea extract).METHODS The analysis of 50％ methanol extract of this drug was performed on a 35 ℃ thermostatic Shimadzu Wonda Cract ODS-2 column (4.6 mm ×250 mm,5 μm),with the mobile phase comprising of 0.5％ acetic acid (A)-acetonitrile (B) flowing at 1.0 mL/min in a gradient elution manner,and the detection wavelength was set at 280 nm.With epigallocatechin gallate as an internal standard,the relative correction factors of epigallocatechin,catechin,epicatechin,gallocatechin gallate and epicatechin gallate were calculated,from which the content determination was made.RESULTS Six constituents showed good linear relationships within their own ranges (r ≥ 0.999 8),whose average recoveries were 96.00％-98.47％ with the RSDs of 2.09％-2.91％.The results obtained by QAMS method approximated those obtained by external standard method.CONCLUSION This simple and reliable method can be used for the quality control of Xinnaojian Capsules (Tablets).

Quantitative Analysis of the Flavonoid Content in the Leaves of Boehmeria nivea and Related Commercial Products

Content analysis of flavonoids (epicatechin, epicatechin gallate, and rutin) present in the leaves of Boehmeria nivea (originating from Geumsan-myeon, Biin-myeon, Hansan-myeon, and Baeksu-eup) and their commercial products (ramie tteok, ramie songpyeon, ramie bory-tteok, and ramie tea) was conducted by HPLC. The content of epicatechin, epicatechin gallate, and rutin was highest in the leaves of B. nivea from Geumsanmyeon (0.138 mg/g), Baeksu-eup (1.654 mg/g) and Geumsan-myeon (12.205 mg/g), respectively. With respect to commercial products, the content of epicatechin and epicatechin gallate was highest in ramie tea, with concentrations of 1.879 and 1.090 mg/g, respectively. Given these flavonoid concentrations, B. nivea leaf extracts have the potential to be used as additives in natural medicinal products, health supplements, and beverages.

Simultaneous determination six components in oolong tea by HPLC / 中国药学杂志

OBJECTIVE: To develop an HPLC method for simultaneous determination five eatechins, including (+)-catechin, epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate and (-)-epigallocatechin-3-gallate, as well as caffeine in Oolong tea. METHODS: The HPLC analysis was carried out on a Grace Allitima C18 column (4.6 mm × 250 mm, 5 μm), with a gradient elution acetonitrile-0.2% acetic acid at the flow rate 1.0 mL · min-1. The detective wave length was set at 280 nm, and the column temperature was set at 35℃. RESULTS: The calibration curve was linear within the range 5.95-952 μg · mL-1 for catechin, 6.36-1018 μg · mL-1 for epicatechin, 6.55-1048 μg · mL-1 for epigallocatechin, 7.80-1248) μg · mL-1 for epigallocatechin gallate, 10.83-1732 μg · mL-1 for epigallocatechin-3-gallate, and 13.38-2 140 μg · mL-1 for caffeine, respectively. The average recoveries for six determined marker compounds were 99.12%-102.12%. CONCLUSION: This method is simple, accurate, and practical for quality control Oolong tea. There are some differences in the contents the six marker compounds in the samples from different producing areas and different collection periods.