Anti-glycation, Whitening, Anti-ageing Food and Cosmetics Ingredient
Caffeoyl glucose (1-caffeoyl-O-β-D-glucopyranoside) and quercetin glucoside (quercetin 3-O-β-D-glucopyranoside) as bioactive components of Sakura Extract.
Inhibition of AGEs production
Bioactive components of Sakura Extract and crude Sakura Extract were added to buffer solution containing D-glucose and bovine serum albumin at 60°C and left to stand for 2 days. Crude Sakura Extract (100μg/mL) significantly inhibited the production of AGEs. Meanwhile, the major bioactive component, caffeoyl glucose significantly inhibited the production of AGEs at concentration as low as 10μg/mL. There were trace amount of hydroxyl caffeoyl glucoses in Sakura Extract, cinnamoyl glucose and coumaroyl glucose, but the inhibitory potency in AGEs production was weak. Although flavonoid glycosides were miner components, they showed strong inhibitory potency. Quercetin glucoside exerted inhibitory effect of two-fold stronger than that of kaempferol glucoside in IC50.
Inhibition of fibroblasts apoptosis
Accumulation of AGEs in skin triggers skin damage and apoptosis of fibroblasts. The effect of Crude Sakura Extract and its bioactive components on carboxylmethyl lysine (CML)-collagen induced fibroblasts apoptosis was examined. Sakura Extract, caffeoyl glucose and quercetin glucose decreased caspase activity, meaning fibroblasts apoptosis were suppressed. The effect of caffeoyl glucose was outstanding in the inhibition. Sakura Extract is potentially beneficial as an anti-ageing agent.
Promotion of collagen formation in fibroblasts
Fibroblasts were cultured in collagen containing medium and treated with glyoxal, a glycation inducer. Regularly, fibroblasts produces collagen lattice when cultured in collagen containing medium. As illustrated in following figures, growth of fibroblasts and collagen lattice formation were enhanced in the presence of Sakura Extract of 100μg/mL and 1000μg/mL. Sakura Extract was suggested to prevent glycation of fibroblasts and to be effective in maintaing extracellular collagen matrix.
Inhibition of AGEs production in fibroblasts
Normal human fibroblasts were treated with glyoxal (glycated intermediate) and incubated for 5 days, then skin glycation was analyzed by Western-blotting method. As illustrated in following figure, Sakura Extract at 10μg/mL significantly inhibited the production of AGEs by glyoxal (indicated as thinner band), compared with control group. Caffeoyl glucose inhibited the production of AGEs at 1 and 10μg/mL, but quercetin glucose acted less potent. It was suggested that caffeoyl glucose plays the major role in the inhibitory effect of Sakura Extract on the production of AGEs.
Inhibition of melanin formation in B16 melanoma cells The skin whitening effect of Sakura Extract was examined in B16 melanoma cells. Sakura Extract was added to cell culture and incubated for 3 days. Then cells were crushed by hypersonication followed by absorbance measurement. Sakura Extract demonstrated inhibition of melanin formation in a dose-dependent manner, similar potency with ascorbic acid glucoside (vitamin C).
Inhibition of tyrosinase activity Further experiment was prompted to examined the effect of Sakura Extract on tyrosinase activity which is directly involved in melanogenesis. As illustrated in following fighre, Sakura Extract showed inhibitory effect on tyrosinase activity in a dose-dependent manner, suggesting its skin whitening effect.
Collagen production and matrix formation We added Sakura Extract (30, 100 μg/mL) to human normal diploid fibroblasts and cultured for 3 days. Then released and accumulated type I collagen was detected by Western blotting. In addition, cellular type I collagen was evaluated by Western blotting and RT-PCR. As a result, excreted type I collagen was increased by the treatment of Sakura Extract (30, 100 μg/mL). Cellular type I collagen was also increased.