Inhibition of temperature-sensitive TRPV3 channel by two natural isochlorogenic acid isomers for alleviation of dermatitis and chronic pruritus

Genetic gain-of-function mutations of warm temperature-sensitive transient receptor potential vanilloid 3(TRPV3)channel cause Olmsted syndrome characterized by severe itching and keratoderma,indicating that pharmacological inhibition of TRPV3 may hold promise for therapy of chronic pruritus and skin diseases.However,currently available TRPV3 tool inhibitors are either nonselective or less potent,thus impeding the validation of TRPV3 as therapeutic target.Using whole-cell patch-clamp and single-channel recordings,we report the identification of two natural dicaffeoylquinic acid isomers isochlorogenic acid A(IAA)and isochlorogenic acid B(IAB)that selectively inhibit TRPV3 currents with IC50 values of 2.7±1.3 and 0.9±0.3μmol/L,respectively,and reduce the channel open probability to 3.7±1.2%and 3.2±1.1%from 26.9±5.5%,respectively.In vivo evaluation confirms that both IAA and IAB significantly reverse the ear swelling of dermatitis and chronic pruritus.Furthermore,the isomer IAB is able to rescue the keratinocyte death induced by TRPV3 agonist carvacrol.Molecular docking combined with site-directed mutations reveals two residues T636 and F666 critical for the binding of the two isomers.Taken together,our identification of isochlorogenic acids A and B that act as specific TRPV3 channel inhibitors and gating modifiers not only provides an essential pharmacological tool for further investigation of the channel pharmacology and pathology,but also holds developmental potential for treatment of dermatitis and chronic pruritus.

Effect of Cassia nomame on Small Intestine Movement, Diuresis,and Anti-inflammation in Rats

Objective To investigate the preliminary pharmacological screening of Cassia nomame.Methods The effect of aqueous extract from C.nomame on gastrointestinal motor function was investigated by assessing the intestinal transit rate(ITR)of charcoal modeled into gastrointestinal motility dysfunction(GMD)by the administration of dopamine,atropine,or noradrenaline to the rats,respectively.Diuresis was studied in vivo by estimating the urine output.The anti-inflammatory activity was expressed as the percentage of swelling reduction by comparison on the mean thickness of ear swelling in mice.Results The ITR in these GMD animals was significantly retarded compared to that in normal animals.The retardation,however,was significantly inhibited by the ig administration of C.nomame(2 g/kg)for all GMD animals.The results suggested that C.nomame had the potential for development into a prokinetic agent that could prevent or alleviate GMD in patients.C.nomame increased urine output and suppressed significantly ear swelling induced by dirnethyl benzene in mice.Conclusion C.nomame could increase the gastrointestinal contractile activity of rats and has the effects of diuresis and anti-inflammation.