Table 1 Selected Alkaloids Used in Cosmetics Name Group Occurrence Action Used in cosmetics LD50 References Caffeine Purine alkaloids Caffe ( L.tea ( ), cola ( ), Yerba mate ( paraguariensis ), and guarane ( cupan) Firming, elasticity blood vessels, antioxidant, stimulate hair high, and antiaging Anti-cellulite balms, antiaging creams, highlight creams, and shampoo and conditioners on hair high 80–100 mg/L, 367 mg/kg BW (7,21) Capsaicin Protoalkaloids Chili peppers ( chili ), jalapeño ( annuum ‘ ñ’), and cayenne pepper ( annuum “Cayenne”) Analgesic, antioxidant, weight loss, antibacterial, and thermoregulatory Lipsticks, lip glosses, hair masks, wipes, shampoos, creams, and anti-cellulite balms 512 mg/kg BW (4,30,36,78) Berberine Isoquinoline alkaloids Barberry ( vulgarisand ) abuta ( grandifolia) Antibacterial, antifungal, antimicrobial, antioxidant, and highlight Masks, creams, tonics, balms, and natural sun fi lter factors UVA i UVB 329 mg/kg BW (4,53) Anatabine Pyridine alkaloids Annual paprika ( annuum L.tomatoes ), ( lycopersicum L. eggplant ( melongena L. Infl ammatory, soothing, and regenerative Creams, pastes, tonics, balms, and gels – (75,76) Piperine Piperidine alkaloids Black pepper ( nigrum L. Anti-infl ammatory and anti-cellulite Face creams, lotions, tonics, soaps, and anti–nail biting preparations 330 mg/kg BW (61,62) Spilanhtol (afi nine) Alkiloamids Acmella oleracea Anti-wrinkles, antiaging, antibacterial, and fi rming Antiaging creams, anti-cellulite creams, gels and emulsion care, and aqua extract for cleaning skin 113 mg/kg BW (63,65,67) ALKALOIDS IN COSMETICS 231

JOURNAL OF COSMETIC SCIENCE 232 thicker portions of treated thighs was 2.1 cm. When considering the lower portion (10 cm above the patella), the difference between the fi rst and last evaluation was 1.7 cm, in treated thighs. Caff eine is also an active ingredient in many anti-cellulite cosmetics. This alkaloid shows fi rming and elasticizing the skin. In vitro studies on human hepatoma HepG2 cells have shown that caffeine can slow down lipogenesis and stimulate lipolysis, which may translate into a decrease in the level of fat accumulated in the body (10). Signifi cant decreases in the accumulation of hepatic lipids, such as triglyceride (TG), and cholesterol were observed when HepG2 cells were treated with caffeine in con- centration of 6–24 mM. Caffeine decreased the mRNA level of lipogenesis-associated genes (SREBP1c, SREBP2, FAS, SCD1, HMGR, and LDLR). By contrast, the mRNA level of CD36, which is responsible for lipid uptake and catabolism, was increased. Phosphorylation of MP-activated protein kinase (AMPK) and acetyl-CoA carboxyl- ase were evidently increased when the cells were treated with caffeine as indicated for 24 h. Caffeine effectively depleted TG and cholesterol levels by inhibition of lipo- genesis and stimulation of lipolysis through modulating AMPK-SREBP signaling pathways (11). This was also confi rmed in studies in rats (eight rats per group) that were fed a high-fat diet supplemented with 0, 0.025%, 0.05%, or 0.1% caffeine for 21 d. Authors noted reducing the body fat mass and body fat percentage in a dose-dependent manner in rats fed with a high-fat diet, presumably because of increased lipolysis via catecholamines. Rats receiving 0.025%, 0.05%, and 0.1% caffeine had about 7, 10, and 11 g less body fat mass and 2.8, 3.1, and 4.5% less body fat percentage, respectively, than rats from the control group (12). Caff eine has penetrating properties, unchanged by the thickness of the skin or the occlu- sive layer. The maximal absorption rates of caffeine through the human skin were found to be 2.24 ± 1.43 μg/cm2/h (13). For determination of the maximal absorption rate of Figure 1. Chemical structure of caffeine (6).