Triethanolamine tea

All chemicals were of analytical grade and utilized as received. Cetyltrimethylammonium bromide (CTAB; 99%), tetraethoxysilane (TEOS; 99%), morin hydrate (MH, >85%), phosphate-buffered saline (PBS) pH 7.4 (0.01 M; with NaCl 138 mM and KCl 2.7 mM) and cylindrical dialysis cellulose membranes (3.5 kDa MWCO) were acquired from Sigma-Aldrich (St. Louis, MO, USA). Triethanolamine (TEA; 99%) and ethanol (CH₃CH₂OH; >99%) were acquired from Fisher Scientific (Hampton, NH, USA). Hydrochloric acid (HCl; 37%) was bought from VWR International (Radnor, PA, USA). Deionized water obtained with a Milli-Q system comprising a 0.22 μm filter (Synergy Equipment, Millipore, Burlington, MA, USA) was employed in all experiments.

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).