The principal active constituents of Polygonum capitatum are phenolic acids and flavonoids, such as gallic acid, quercitrin, and quercetin. The aim of this study was to develop and validate a method to determine the three constituents and the corresponding conjugated metabolites of Polygonum capitatum in vivo and to conduct pharmacokinetic studies on the herb, a well-known Miao medicinal plant in China. Gallic acid, quercitrin, and quercetin were analysed by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). Protein precipitation in plasma samples was performed using methanol. For the determination of total forms of analytes, an additional process of hydrolysis was conducted using β-glucuronidase and sulphatase. The analytes were separated on a BEH C₁₈ column (50 mm × 2.1 mm; i.d., 1.7 μm) and quantified by multiple reaction monitoring (MRM) mode. The linear regression showed high linearity over a 729-fold dynamic range for the three analytes. The relative standard deviations of intra- and inter-day measurements were less than 9.5%, and the method was accurate to within −11.1% to 12.5%. The extraction recoveries for gallic acid, quercitrin, and quercetin were 94.3%–98.8%, 88.9%–98.8%, and 95.7%–98.5%, respectively. All samples were stable under short- and long-term storage conditions. The validated method was successfully applied to a comparative pharmacokinetic study of gallic acid, quercitrin, and quercetin in their free and total forms in rat plasma. The study revealed significantly higher exposure of the constituents in total forms for gallic acid and quercetin, while quercitrin was detected mainly in its corresponding free form in vivo. The established method was rapid and sensitive for the simultaneous quantification of free and total forms of multiple constituents of Polygonum capitatum extract in plasma.

Objectives: This in vitro investigation was designed to examine potential neuroprotection by dicaffeoylquinic acids (diCQAs) extracted from a traditional Chinese medicinal herb herba erigerontis and their effects against the toxicity induced by β-amyloid peptide (Aβ25–35). Methods: The neuroblastoma SH-SY5Y cell line was treated with Aβ or 3, 4-diCQA, 3, 5-diCQA or 4, 5-diCQA. 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) reduction was assayed by spectrophotometrical method, lipid peroxidation (malondialdehyde) on the basis of the level of thiobarbituric acid-reactive substance, the activity of superoxide dismutase by the xanthine oxidase procedure, the frequency of apoptosis by flow cytometry, and the levels of α3 and α7 nicotinic acetylcholine receptor (nAChR) subunit proteins by Western blotting. Key findings: When the cells were exposed to Aβ25–35, MTT reduction declined, oxidative stress and apoptosis were enhanced, and the expression of α3 and α7 nAChR subunit proteins was lowered. Expression of the α7 nAChR subunit protein was increased by all three diCQAs, and the level of α3 was increased by 3, 5-diCQA and 4, 5-diCQA. Significantly, pretreatment with diCQAs attenuated the neurotoxic effects of Aβ25–35, a neuroprotective effect in which the upregulation of α7 and α3 nAChR may be involved. Conclusion: The diCQAs exert a protective effect on Aβ-induced neurotoxicity in SH-SY5Y cells and a potential underlying mechanism involving stimulation of nAChRs.

Eucommiae Cortex (EC), a rare, nourishing medicinal herb that is native in China, has good effect in the treatment of hypertension. In this study, we compared tissue distribution of six representative active components of EC extract—genipinic acid (GA), protocatechuic acid (PCA), neochlorogenic acid (NCA), chlorogenic acid (CA), (+)‐pinoresinol di‐O‐β‐D‐glucopyranoside (PDG), and (+)‐pinoresinol 4′‐O‐β‐D‐glucopyranoside (PG)—between normal rats and spontaneously hypertensive rats (SHRs). Each rat was intragastrically given EC extract at a dose of 5.4 g/kg. Rats were sacrificed at 10 min, 30 min, 2 h, and 8 h after administration; six rats were sacrificed at each time point. Then, we quickly harvested their major organs, including heart, liver, spleen, lungs, kidneys, and brain. Using ultraperformance liquid chromatography‐tandem mass spectrometry (UPLC‐MS/MS), we determined the levels of the above mentioned six components in the organs of both types of rats and then analyzed differences in the tissue distribution. The results showed that levels of each component differed between SHRs and the normal group at each time point. As time progressed, the number of organs in which GA distribution in each tissue of SHRs differed from that of the normal group gradually increased: SHRs showed lower GA levels than normal rats. Levels of PG and PDG in both groups at 10 and 30 min were similar. NCA and CA in the SHR group and the normal group at 10 min, 30 min, and 2 h were also similar to some extent. The results indicated that the pathological state of spontaneous hypertension could affect tissue distribution of EC active components in rats.

Erigeron breviscapus, a traditional Chinese medicine, is clinically used for the treatment of occlusive cerebral vascular diseases. We developed a sensitive and reliable ultra-performance liquid chromatography-electrospray-tandem mass spectrometry (UPLC-ESI-MS/MS) method for simultaneous quantitation of chlorogenic acid, scutellarin, and scutellarein, the main active constituents in Erigeron breviscapus, and compared the pharmacokinetics of these active ingredients in sham-operated and middle cerebral artery occlusion (MCAO) rats orally administrated with Erigeron breviscapus extract. Plasma samples were collected at 15 time points after oral administration of the Erigeron breviscapus extract. The levels of chlorogenic acid, scutellarin, and scutellarein in rat plasma at various time points were determined by a UPLC-ESI-MS/MS method, and the drug concentration versus time plots were constructed to estimate pharmacokinetic parameters. The concentration of chlorogenic acid in the plasma reached the maximum plasma drug concentration in about 15 min and was below the limit of detection after 4 h. Scutellarin and scutellarein showed the phenomenon of multiple absorption peaks in sham-operated and MCAO rats, respectively. Compared with the sham-operated rats, the terminal elimination half-life of scutellarein in the MCAO rats was prolonged by more than two times and the area under the curve of each component in the MCAO rats was significantly increased. The results showed chlorogenic acid, scutellarin, and scutellarein in MCAO rats had higher drug exposure than that in sham-operated rats, which provided a reference for the development of innovative drugs, optimal dosing regimens, and clinical rational drug use.