Neobaicalein Inhibits Th17 Cell Differentiation Resulting in Recovery of Th17/Treg Ratio through Blocking STAT3 Signaling Activation.

Huangqin is the dried root of Scutellaria baicalensis Georgi, which has been widely utilized for heat-clearing (Qingre) and dewetting (Zaoshi), heat-killed (Xiehuo) and detoxifying (Jiedu) in the concept of Traditional Chinese Medicine and is used for treating inflammation and cancer in clinical formulas. Neobaicalein (NEO) is of flavonoid isolated from Huangqin and has been reported to possess prominent anti-inflammatory effects in published work. Th17/Treg balance shift to Th17 cells is an essential reason for autoimmune inflammatory diseases. However, the role NEO plays in Th17 and Treg and the underlying mechanism has not been elucidated yet. Network pharmacology-based study revealed that NEO predominantly regulated IL-17 signaling pathway. Moreover, our result shown that NEO (3-30 µmol/L) down-regulated Th17 differentiation and cellular supernatant and intracellular IL-17A level and tumor necrosis factor α production in a concentration-dependent manner. The further mechanism research revealed that NEO also specifically inhibited phosphorylation of STAT3(Tyr725) and STAT4 (Y693) without influence on activation of STAT5 and STAT6 in splenocytes. Immunofluorescence results illuminated that NEO effectively blocked STAT3 translocated into nucleus. Interestingly, NEO at appreciated dose could only inhibit Th17 cell differentiation and have no effect on Treg differentiation. The present study revealed that NEO effectively inhibited Th17 cell differentiation through specifically blocking the activation of STAT3 signaling without inactivation of STAT5 and STAT6. Additional inhibitory effect on activation of STAT4 by NEO also suggested the potential for antagonism against Th1 differentiation. All work suggested that NEO may be a potential candidate for immunoregulation and treating autoimmune inflammatory diseases through inhibiting immune cell viability and T cell differentiation.

Development of a hydrophilic interaction chromatography-UPLC assay to determine trigonelline in rat plasma and its application in a pharmacokinetic study.

AIM: Trigonelline (Tr) is the second most abundant alkaloid in coffee beans. This study developed an assay combining hydrophilic interaction chromatography with ultra performance liquid chromatography (HILIC-UPLC) for the quantification of Tr in rat plasma to determine its pharmacokinetic behavior. METHODS: After the administration of Tr by gavage as well as intravenous injection and that of methanol extract of coffee beans (MECB) orally, blood samples from the experimental rats were analyzed using the HILIC-UPLC assay. Pharmacokinetic parameters were determined using the standard non-compartmental method and calculated using Practical Pharmacokinetic Program Version 87/97. RESULTS: The HILIC-UPLC assay was validated with the linear range of 0.12-100 µg·mL(-1) and a lower limit of quantitation of 0.12 µg·mL(-1). Its accuracy, precision, recovery, and stability were within acceptable limits. The AUC(0-∞) (where AUC is the area under the plasma concentration-time curve) values were determined to be (4 066.83 ± 1 244.41) and (3 544.29 ± 908.80) min·µg·mL(-1) after Tr was orally and intravenously administered, respectively. It was (4 566.75 ± 1 435.64) min·µg·mL(-1) after MECB was orally administered. The absolute bioavailability of Tr alone reached 57.37%, whereas that of Tr in MECB was 64.42%. The relative bioavailability of the alkaloid was 112.29%. CONCLUSIONS: The HILIC-UPLC assay for Tr determination is simple and accurate, and also exhibits good reproducibility. The bioavailability of stand-alone Tr and that of Tr in MECB were both good. Tr alone and that in MECB orally administered did not exhibit any significant difference.