Research on the antipruritic active ingredients of Mikania micrantha

Mikania micrantha is a perennial liana of the genus Mikania of the Asteraceae family. It is a commonly used medicine in South America for treating fever, malaria, dysentery, snake bites, etc. Because of its strong adaptability and ability to inhibit the growth of its associated plants, Mikania micrantha is considered an invasive species in China and is known as a plant killer. Preliminary studies have shown that Mikania micrantha has an antipruritic effect, but the antipruritic active substance is not yet clear. In this study, a 4-aminopyridine-induced itching model in mice was used to determine the antipruritic effects of petroleum ether, ethyl acetate, ethanol extraction site, and Mikania micrantha volatile oil. GC-MS was used to analyze the components of the antipruritic fractions, combined with mice itch-causing models to study the antipruritic effects of β-caryophyllene and humulene. The safety of β-caryophyllene was preliminarily evaluated through the acute toxicity test of mice skin. The ethyl acetate and volatile oil of Mikania micrantha have apparent antipruritic effects. Humulene and β-caryophyllene have a quantitative-effective relationship to inhibit itching in mice. The acute toxicity test of mouse skin showed that β-caryophyllene has no acute toxicity. This study indicated that the main antipruritic active ingredients of Mikania micrantha are β-caryophyllene and humulene.

Antinociceptive action of Vanillosmopsis arborea in male mice

OBJECTIVE

Vanillosmopsis arborea Baker (Asteraceae) has high economic value from Chapada to Araripe and its bark essential oil is a potential source of alpha-bisabolol. The present study aimed to elucidate the antinociceptive and antipruritic properties of the essential oil of V. arborea Baker (EOVA) in mice.

MATERIALS AND METHODS

The antinociceptive activity was assessed using the capsaicin, glutamate, hot plate and cold allodynia tests. The antipuritic effects were also verified based on histamine-induced scratching behavior.

RESULTS

EOVA reduced the paw licking induced by capsaicin, but not that induced by glutamate. The essential oil increased the latency time in the hot plate, attenuated the cold allodynia induced by acetone and inhibited histamine-induced scratching behavior.

CONCLUSION

The experimental data demonstrated that EOVA showed central and peripheral antinociceptive activity and antipruritic effect.

Novel inhibitory effects of cardamonin on thromboxane A2-induced scratching response: Blocking of Gh/transglutaminase-2 binding to thromboxane A2 receptor

Alpinia katsumadai is known to suppress thromboxane A2 (TXA2) receptor agonist-induced scratching in mice. The specific components of A. katsumadai responsible for these biological effects, however, are not known. In the present study, we investigated whether cardamonin (CDN), one of major principles of A. katsumadai, has suppressive effects on TXA2-induced scratching in mice. Scratching induced by U46619 (the TXA2 receptor agonist) at a dose of 10nmol/site was shown to be suppressed by CDN (0.1nmol-0.5nmol/site). Suppression of the U46619-induced scratching response by CDN was found to be unrelated to competition with the ligand at the TXA2 receptor, since CDN did not suppress [(3)H] SQ29548 (the TXA2 receptor antagonist) binding to TXA2 receptor. TXA2 receptor expression in A549, HaCaT, and SH-SY5Y cell lines was examined and determined to be significant in the A549 and SH-SY5Y cell lines. Further, binding of high molecular G protein Gh/transglutaminase-2 (Gh/Tgase-2) to TXA2 receptor was confirmed in the A549 and SH-SY5Y cells by co-immunoprecipitation. CDN suppressed the binding of TXA2 receptor with Gh/Tgase-2, which also acts as a G protein involved in TXA2 signaling. These results suggested that CDN suppresses TXA2 receptor agonist-induced scratching by suppressing TXA2 signaling, specifically via blocking of the binding of Gh/Tgase-2 to TXA2 receptor.