Journal of natural medicines
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Indole is produced from dietary tryptophan by tryptophanase in intestinal bacteria, such as Escherichia coli. In the liver, indole is converted into indoxyl sulfate, a uremic toxin and risk factor for chronic kidney disease (CKD). Probiotics and prebiotics are currently used for suppressing CKD, but there are no drugs that directly suppress indole production. ⋯ The 20% methanol-eluted fraction of aqueous rhubarb extract significantly suppressed indole production, and the eluate constituent rhein 8-O-β-D-glucopyranoside (RG) contributed to this effect in a concentration-dependent manner. The effect of RG depended on the anthraquinone core substructure, i.e., the aglycone moiety (rhein) of RG, which appeared to inhibit the tryptophanase function in gut microbiota. Thus, in addition to earlier reports that rhubarb is an effective CKD treatment, our study demonstrated that the anthraquinone moiety in rhubarb prevents uremic toxin production via functional changes in gut microbiota, which suppresses CKD progression.
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Daiokanzoto (DKT) exerts its laxative effect via colonic inflammation caused by sennoside A in Daio (rhubarb). Previously, we showed that the laxative effect of sennoside A is related to decreased aquaporin-3 (AQP3) expression in mucosal epithelial cells due to colonic inflammation. We also found that a combination of glycyrrhizin, an ingredient in Kanzo (glycyrrhiza), and sennoside A attenuates the inflammatory response induced by sennoside A and reduces its laxative effect. ⋯ Although the relative abundance of gut microbiota after repeated DKT administration was similar to that after control treatment, Daio reduced Lactobacillaceae, Bifidobacteriaceae, and Bacteroidaceae levels and markedly increased Lachnospiraceae levels. In this study, we show that DKT has a sustained laxative effect, even upon repeated use, probably because it maintains decreased AQP3 expression and gut microbiota homeostasis. This outcome therefore indicates that DKT can be used as a long-term treatment for chronic constipation.
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Evodiae fructus (EF), a fruit of Evodia rutaecarpa Bentham, has long been used as an analgesic drug in traditional Chinese and Japanese medicine. However, the underlying molecular mechanism of its pharmacological action is unclear. Here, using calcium imaging, whole-cell patch-clamp recording, and behavioral analysis, we investigated the pharmacological action of EF and its principal compound, evodiamine, on the transient receptor potential (TRP) V1 channels. ⋯ Pretreatment with evodiamine reduced capsaicin-induced currents significantly. Furthermore, the in vivo pre-treatment of evodiamine suppressed thermal hyperalgesia induced by intraplantar injection of capsaicin in rats. These results identify that the analgesic effect of EF and evodiamine may be due to the activation and subsequent desensitization of TRPV1 in sensory neurons.
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Yinhuapinggan granule (YHPG), a Chinese medicine granule based on Ma-Huang-Tang (Ephedra Decoction) and the clinical experience of Professor Wan Haitong, is used in traditional Chinese medicine (TCM) for the treatment of colds, influenza, fever, inflammation and cough. This study investigated the antiviral effects of YHPG on the production of inflammatory cytokines in influenza virus (IFV)-infected mice and evaluated the effect of YHPG on the expression of NF-κB p65 and the level of key signaling molecules in the TLR4 signaling pathway. ⋯ Furthermore, the expression of TLR4, MyD88, TRAF6 and NF-κB p65 at the mRNA and protein level was significantly lower in the YHPG (15 and 30 g/kg) treatment groups than in the IFV control group. These results suggest that YHPG has antiviral effects in IFV-infected mice, which is associated with the inhibition of the TLR4-MyD88-TRAF6 signaling pathway and the expression of NF-κB p65.
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Shakuyakukanzoto (SKT) is a kampo medicine composed of equal proportions of Glycyrrhizae radix (G. radix) and Paeoniae radix (P. radix). A double-blind study reported that SKT significantly ameliorated painful muscle cramp in cirrhosis patients without the typical severe side effects of muscle weakness and central nervous system (CNS) depression. Previous basic studies reported that SKT and its active components induced relaxation by a direct action on skeletal muscle and that SKT did not depress CNS functions; however, why SKT has a lower incidence of muscle weakness remains unknown. ⋯ Our study demonstrated that SKT and five G. radix isolates, which are responsible for the antispasmodic effect of SKT, did not inhibit the twitch contraction in contrast to dantrolene sodium, a direct-acting peripheral muscle relaxant, indicating that the mechanisms of muscle contraction of SKT and dantrolene in skeletal muscle differ. These findings suggest that SKT does not reduce the contractile force in skeletal muscle under physiological conditions, i.e., SKT may have a low risk of causing muscle weakness in clinical use. Considering that most muscle relaxants and anticonvulsants cause various harmful side effects such as weakness and CNS depression, SKT appears to have a benign safety profile.