Span 80

Capsaicin standard and capsicum oleoresin extract (chili extract) were obtained from Bangkok Lab and Cosmetic, Ratchaburi, Thailand. Glyceryl behenate (GBH), or Compritol^® 888ATO, was obtained from Gattefossé (Lyon, France). Glyceryl monostearate (GMS), cetyl alcohol (COH), stearyl alcohol (SOH), isopropyl myristate (IPM), and jojoba oil were purchased from Namsiang (Bangkok, Thailand). Tween^® 80 and Span^® 80 were purchased from NOF Corporation (Tokyo, Japan). Acetonitrile, methanol (HPLC grade), glacial acetic acid, ethanol (AR grade), and deionized water were purchased from RCI Labscan (Bangkok, Thailand). Carbopol 940 was purchased from Universal Preserv-A-Chem (NJ, USA). High-viscosity hydroxypropyl methyl cellulose (HV HPMC, viscosity 2600–5600 cP) and isopropanol were purchased from Sigma-Aldrich (MO, USA). Triethanolamine (TEA) was purchased from Fisher Scientific (PA, USA). The fully differentiated human epidermis (EpiDerm^TM) specimen, EpiDerm culture medium, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay kit were purchased from MatTek Corporation (MA, USA). Quantikine^® human Interleukin 1 alpha (IL-1 α) ELISA kit was purchased from R&D Systems (MN, USA).

A capsaicin standard and a chili extract from Capsicum chinense were obtained from Bangkok Lab and Cosmetic Co., Ltd., Ratchaburi, Thailand. Glyceryl monostearate (GMS), cetyl alcohol (COH), and isopropyl myristate (IPM) were purchased from Namsiang, Bangkok, Thailand. Tween^® 80 and Span^® 80 were purchased from NOF Corporation, Tokyo, Japan. All the other chemicals were of the highest grade available. All the solutions were prepared with distilled water.