Xu Yuhang, Li Jing, Cui Mengyao, Li Xiaoliang, Zhai Hongyan, Wu Deling, Chu Xiaoqin
School of Pharmacy, Anhui University of Chinese Medicine, Hefei, China.
Anhui Joyfar Pharmaceutical Research Institute Co., Ltd., Hefei, China.
Front Pharmacol. 2025 Apr 25;16:1560271. doi: 10.3389/fphar.2025.1560271. eCollection 2025.
Cinnamomi Ramulus (CR) is the dried bark of Cinnamomum cassia Presl, Lauraceae. Puerariae Lobatae Radix (PLR) is the dried root of the Pueraria lobata (Wild.) Ohwi, Leguminosae. This Chinese herb couple come from the classic formula "Gui Zhi Ge Gen Tang," which is included in the TCM classic "Treatise on Febrile Diseases." Our previous studies have found that CR related herbal compound and PLR related herbal compound are useful in improving type 2 diabetes mellitus (T2DM), which is expected to be an antidiabetic candidate with fewer side effects. However the mechanism of action of CR-PLR on T2DM has not yet been fully elucidated.
The decoction of CR-PLR was prepared by aqueous extraction method and the composition of it was analyzed using UPLC-Q-TOF-MS and HPLC. The T2DM model was established by intraperitoneal injection of streptozotocin, and the groups of drug administration were metformin, CR, PLR and CR-PLR groups, with continuous gastric gavage for 6 weeks, and the serological indexes were detected by ELISA. The abundance of rats' gut flora was detected by 16s rDNA sequencing, and changes in the content of short-chain fatty acids (SCFAs) in feces of rats were detected by GC-MS; and the expression of G protein-coupled receptor43 (GPR43) and glucagon-like peptide-1 (GLP-1) proteins in colonic tissues of rats were detected by Western Blot. The pharmacokinetic behavior of CR-PLR was investigated in both normal and T2DM model rats. Caco-2/HT29 co-culture cell model was established in vitro, transepithelial electrical resistance (TEER) and ALP activity of epithelial cells were measured to evaluate cell model integrity and cell polarization, Alcian blue staining was used to verify the presence of mucus production, and CCK-8 was used to screen drug safe concentration. The bidirectional transport of puerarin was studied to investigate the transport mechanism of puerarin and the effect of leuric acid on puerarin transport.
The results indicated that CR-PLR can stimulate intestinal flora, increase the content of SCFAs, activate intestinal GPR43 protein, and promote the secretion of GLP-1 in intestinal L cells, which plays a therapeutic role in the treatment of T2DM. Additionally, cytology and pharmacokinetics experiments have proved that cinnamic acid (CA) can enhance the absorption and transport of puerarin (PUR) by inhibiting the efflux effects mediated by P-gp and MRP efflux transporters. The present study exhibites the scientific and reasonable menaning of this novel Chinese herb couple treating T2DM from the perspecives of pharmacodynamics and pharmacokinetics.
桂枝为樟科植物肉桂的干燥树皮。葛根为豆科植物野葛的干燥根。这味中药对出自经典方剂“桂枝葛根汤”，载于中医经典《伤寒论》。我们之前的研究发现，桂枝相关草药化合物和葛根相关草药化合物对改善2型糖尿病（T2DM）有效，有望成为副作用较少的抗糖尿病候选药物。然而，桂枝 - 葛根对T2DM的作用机制尚未完全阐明。
采用水提法制备桂枝 - 葛根水煎液，并运用超高效液相色谱 - 四极杆飞行时间质谱联用仪（UPLC - Q - TOF - MS）和高效液相色谱法（HPLC）对其成分进行分析。通过腹腔注射链脲佐菌素建立T2DM模型，给药组分别为二甲双胍、桂枝、葛根和桂枝 - 葛根组，连续灌胃6周，采用酶联免疫吸附测定法（ELISA）检测血清学指标。采用16s rDNA测序检测大鼠肠道菌群丰度，用气相色谱 - 质谱联用仪（GC - MS）检测大鼠粪便中短链脂肪酸（SCFAs）含量变化；采用蛋白质免疫印迹法（Western Blot）检测大鼠结肠组织中G蛋白偶联受体43（GPR43）和胰高血糖素样肽 - 1（GLP - 1）蛋白的表达。在正常大鼠和T2DM模型大鼠中研究桂枝 - 葛根的药代动力学行为。体外建立Caco - 重29共培养细胞模型，测量上皮细胞的跨上皮电阻（TEER）和碱性磷酸酶（ALP）活性以评估细胞模型完整性和细胞极化，采用阿尔新蓝染色验证黏液分泌情况，并用细胞增殖 - 毒性检测试剂盒（CCK - 8）筛选药物安全浓度。研究葛根素的双向转运，以探讨葛根素的转运机制以及阿魏酸对葛根素转运的影响。
结果表明，桂枝 - 葛根可刺激肠道菌群，增加SCFAs含量，激活肠道GPR43蛋白，并促进肠道L细胞分泌GLP - 1，在T2DM治疗中发挥治疗作用。此外，细胞学和药代动力学实验证明，肉桂酸（CA）可通过抑制P - 糖蛋白（P - gp）和多药耐药相关蛋白（MRP）外排转运体介导的外排作用增强葛根素（PUR）的吸收和转运。本研究从药效学和药代动力学角度展现了这味新型中药对治疗T2DM的科学性和合理性。
