Yeon Su Jeong

TRPV1 antagonist can suppress the atopic dermatitis-like symptoms by accelerating skin barrier recovery

BACKGROUND Transient receptor potential vanilloid type 1 (TRPV1) is a cation channel activated by diverse obnoxious stimuli like capsaicin, low pH or heat. Recently, it was revealed that TRPV1 might be deeply associated with skin permeability barrier function, suggesting that modulation of TRPV1 might be beneficial for the skin disorders with barrier damages. OBJECTIVE We aimed to investigate whether the blockade of TRPV1 activation might accelerate skin barrier recovery and alleviate atopic dermatitis (AD)-like symptoms, employing a novel TRPV1 antagonist, PAC-14028. METHODS TRPV1 antagonistic effects of PAC-14028 in human keratinocytes and skin were confirmed through capsaicin-evoked calcium influx assay and capsaicin-induced blood perfusion increase. Effects of PAC-14028 on skin barrier recovery were examined in vivo tape-stripping-induced barrier disruption in hairless mice. To determine the effects of PAC-14028 on AD, Dermatophagoides farina (Df)- and oxazolone (OXZ)-induced AD models were employed. RESULTS PAC-14028 could inhibit capsaicin-evoked calcium influx in keratinocytes at sub-micromolar concentrations. This potent TRPV1 antagonistic activity in keratinocytes was manifested in vivo as the blockade of capsaicin-induced blood perfusion increase, and the accelerated barrier recovery from tape-stripping-induced barrier damages in hairless mice. PAC-14028 could also attenuate dermatitis-associated barrier damages in Df and OXZ models as determined by lower TEWL (trans-epidermal water loss), reformation of neutral lipid layer and reversion of changes in loricrin and filaggrin expression. Importantly, along with accelerated recovery of skin barrier function, PAC-14028 alleviated the general AD-like symptoms, including serum IgE increase, mast cell degranulation, scratching behavior and clinical severity of dermatitis. CONCLUSIONS These results reflect that the blockade of TRPV1 activation can suppress the atopic dermatitis-like symptoms by accelerating skin barrier recovery.

Chain-branched acyclic phenethylthiocarbamates as vanilloid receptor antagonists.

A series of acyclic phenethylthiocarbamate derivatives have been synthesized, and their antagonist effect against vanilloid receptor tested. Chain branching led to a significant change in antagonist activity of the parent molecule. Ethyl-branched 1e showed a 6.3 microM of IC(50) value in 45Ca(2+)-influx assay.

Synthesis of 2-substituted-pyrrolidinethiourea derivatives and their antagonist effect on vanilloid receptor

Four pyrrolidine derivatives were prepared by the formation of a 5-membered ring based on capsazepine. Among them, the two carbon extended derivatives, 4a (IC(50)=55 microM) and 4b (IC(50)=3 microM), both showed different levels of antagonist activity against the vanilloid receptor in a (45)Ca(2+)-influx assay.

Evaluation of anti-platelet and anti-thrombotic effects of cilostazol with PFA-100® and Multiplate® whole blood aggregometer in vitro, ex vivo and FeCl3-induced thrombosis models in vivo

We evaluate the anti-platelet and anti-thrombotic effects of cilostazol using Multiplate® and PFA-100® in vitro and ex vivo with freshly isolated rat whole blood and in vivo venous and arterial thrombosis models in the same species, in an effort to assess the sensitivity of the whole blood aggregometer assays without potential issues of species differences. In vitro assay of anti-platelet effects of cilostazol against collagen-induced aggregation using Multiplate® produced a graded dose-dependent inhibition curve with IC50 value of 75.4 ± 2.4 μM while it showed a highly sensitive and all-or-none type inhibition response from 25 μM in PFA-100®. Interestingly, cilostazol manifested anti-thrombotic effects in vivo at much lower plasma concentrations than the effective concentrations measured in ex vivo or in vitro aggregation tests using PFA-100® or Multiplate®. In addition, the tail bleeding time measurement demonstrated that rats have lower sensitivity to the anti-platelet effects of cilostazol than mice. These results suggest that the detailed comparative evaluation of whole blood aggregometer assays with anti-thrombotic effects in vivo should be preceded before the application of these methods for the pharmacodynamic studies of anti-thrombotic agents.

Silicon switch approach in TRPV1 antagonist MK-056 and its analogues.

In searching for opportunities to exploit the benefits of silicon in TRPV1 research, we tried to investigate the pharmacological effects of sila-substitution (C/Si exchange) of tert-butyl group in the MK-056 series. Compound 13a, with a 4-positioned trimethylsilanyl group on the B ring in place of tert-butyl group, exhibited the most potent antagonist activity with IC(50) values of 0.15 microM, which is almost equipotent with that of MK-056. This is the first example that tert-butyl group on MK-056 series can be replaced to the other substituent without loss of activity.

Antimelanogenic activity of a novel adamantyl benzylbenzamide derivative, AP736: a randomized, double-blind, vehicle-controlled comparative clinical trial performed in patients with hyperpigmentation during the summer

AP736 is a novel compound with an adamantyl benzylbenzamide moiety that has shown antimelanogenic activity in melanocytes in vitro and in artificial skin equivalent through the inhibition of key melanogenic enzymes and suppression of the cAMP‐phosphokinase A‐cAMP response element‐binding protein signaling pathway. To estimate the clinical effectiveness of AP736 for the treatment of facial hyperpigmentation, we examined the efficacy and safety of a topical formulation containing AP736 compared with a vehicle formulation in human facial skin. To evaluate the degree of whitening when used in a real‐life situation, subjects with hyperpigmentation conditions were selected and the trial was performed from mid‐May to the end of June, when there are strong UV rays in Korea.