Mechanism and inhibitory effects of cactus (Opuntia dillenii) extract on melanocytes and its potential application for whitening cosmetics.

Penghu cactus (Opuntia dillenii [Ker.] Haw) is a cactus plant that commonly grows in Penghu Island, Taiwan, Republic of China (ROC). However, still lack of scientific study on the Opuntia dillenii [Ker.] Haw extract on skin-whitening-associated tyrosinase activity and melanin production. The activities of its extract in melanogenesis were investigated in this article. In this experiment, we used an extract from the Penghu cactus (Opuntia dillenii [Ker.] Haw) to study its tyrosinase inhibition, anti-melanin generation, UV-protection effects and wound healing capacity in B16-F10 melanocytes. Without reducing cell growth greatly or causing cell death, 20 g/L cactus extract effectively inhibited the melanin production of B16-F10 cells, and melanogenesis was induced by 3-isobutyl-1-methylxanthine. The cactus extract could also promote cell proliferation. Cactus extract treatment decreased the mRNA expression of insulin-like growth factor 1 (IGF-1) and vascular endothelial growth factor (VEGF) and increased that of transforming growth factor ß (TGF-ß). Thus, it could reduce cell melanin production and promote cell growth but by also reducing IGF-1 and VEGF mRNA expression, may reduce wound scarring and prevent tumor proliferation and swelling. Increasing TGF-ß mRNA expression can help increase collagen to remove wrinkles and help in wound healing. Skin patch test results agreed with in vitro results with B16-F10 melanoma cells. The cactus extract significantly inhibited tyrosinase activity and reduced melanin production, showing a whitening effect on skin tests. Cactus may be a good natural candidate for inhibiting melanin production and promoting cell proliferation.

Roselle Anthocyanins: Antioxidant Properties and Stability to Heat and pH.

Roselle is rich in anthocyanins and is traditionally used to prepare a bright red beverage by decoction. However, heat treatment and different pH environments are often encountered during food processing, and these factors are often detrimental to anthocyanins. Therefore, it is very important to understand the influence of pH and heat treatment on anthocyanins for the application of roselle. This study determined the antioxidant properties of roselle extract, explored changes in the color and anthocyanin content in different pH environments, and evaluated the thermal stability of roselle anthocyanins using kinetic equations. The results showed that the roselle extract is rich in anthocyanins and has good antioxidant capacity (DPPH IC50 = 4.06 mg/mL, ABTS IC50 = 3.7 mg/mL). The anthocyanins themselves exhibited a certain degree of heat resistance and good color stability in an acidic environment. In contrast, they degraded very quickly and exhibited significant changes in color in a low-acid environment. The activation energy (Ea) ranges of the anthocyanins in the acidic and low-acid environments were quite different at 55.8⁻95.7 and 31.4⁻74.9 kJ/mol, respectively. Thus, it can be concluded that roselle anthocyanins are susceptible to heat treatment in a low-acid environment, affecting their quality and appearance; however, they can serve as a good source of functional ingredients and color in an acidic environment.

Quality Characterization and Oxidative Stability of Camellia Seed Oils Produced with Different Roasting Temperatures.

In this study, the effects of roasting camellia (Camellia oleifera Abel.) seed oils at different temperatures (65°C, 100°C, 120°C, and 140°C) on the oxidative stability and composition of the oils were investigated. The results showed that, in terms of the quality of the oils, the roasting temperature influenced the total phenolic content (which ranged from 1.64～2.45 GAE mg/g for the different oils) and total flavonoid content (which ranged from 0.36～0.45 QE mg/g for the different oils), while the fatty acid profile and tocopherol content were not influenced by the roasting temperature. We also investigated the kinetic parameters of camellia seed oil during oxidation via Rancimat (at temperatures ranging from 110~140°C). It turned out that the natural logarithms of the oxidative stability index (OSI) varied linearly with respect to temperature (R2: 0.958～0.997). This was done on the basis of the Arrhenius equation that indicates that the activation energies (Ea) for oxidative stability are 65.7～78.4 KJ/mol. Simultaneously, we found that increasing the roasting temperature could increase the antioxidant stability of Maillard reaction products in camellia seed oil. The effects of roasting include the assurance that the camellia seed oil so produced will comply with the relevant governmental health codes and standards and have a longer shelf life.