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Modelling and analysis of skin pigmentation
Published in Ahmad Fadzil Mohamad Hani, Dileep Kumar, Optical Imaging for Biomedical and Clinical Applications, 2017
Ahmad Fadzil Mohamad Hani, Hermawan Nugroho, Norashikin Shamsudin, Suraiya H. Hussein
Figure 4.70 shows the skin reflectance data obtained from normal skin areas, melasma lesion and vitiligo lesion for various SPTs collected during the observational study. There are only three types of SPT collected during the second study. Melasma and vitiligo represent the different types of skin pigmentation disorders. In melasma, skin areas appear darker than the surrounding skin due to the higher amount of pigment melanin. A higher production of melanin indicates that the light absorbance will be higher compared to the surrounding normal skin. Higher absorbance level will be reflected on the data of skin reflectance, which, in this case, will be lower than that of the normal skin, as shown in Figure 4.70.
Flavonoids from Quercus Genus: Applications in Melasma and Psoriasis
Published in Tatjana Stevanovic, Chemistry of Lignocellulosics: Current Trends, 2018
Esquivel-García Roberto, Velázquez-Hernández María-Elena, Valentín-Escalera Josué, Valencia-Avilés Eréndira, Rodríguez-Orozco Alain-Raimundo, Martha-Estrella García-Pérez
Melasma, from the greek “melas” which means black, is a chronic acquired pigmentary disorder characterized by symmetrical, irregular, hyperpigmented (light to dark brown) macules on sun exposed skin areas, mainly face and neck (Ferreira Cestari et al. 2014, Kwon et al. 2016). The pathogenesis of melasma is complex, therefore has not been fully elucidated. However, chronic ultraviolet (UV) light exposure, hormone consumption, pregnancy, inflammation, use of cosmetics and photosensitizing drugs are recognized as triggering factors for its occurrence (Ortonne et al. 2009, Ferreira Cestari et al. 2014).
Antioxidant and anti-tyrosinase activities of quercetin-loaded olive oil nanoemulsion as potential formulation for skin hyperpigmentation
Published in Journal of Dispersion Science and Technology, 2022
Cristiane C. Silva, Rogério B. Benati, Taís N. C. Massaro, Karina C. Pereira, Lorena R. Gaspar, Priscyla D. Marcato
Hyperpigmentation disorders, which include postinflammatory hyperpigmentation, solar lentigos and melasma, are characterized by dark spots on the skin.[1] Specifically, melasma is a chronic acquired condition of hypermelanosis characterized by homogeneous spots with irregular borders from light to dark brown, distributed on the epidermis, very frequent on the face.[2,3] The conventional treatment for this hyperpigmentation[2] consists of applying sunscreen and using 2-5% topical hydroquinone alone or in combination with retinoic acid (0.05-0.1%) since both interfere in melanogenesis and also retinoic acid, as a chemical peel, which acts on the desquamation of the epidermis.[2,4,5] Hydroquinone is a gold standard for skin hyperpigmentation as it prevents melanin synthesis with the inhibition of the tyrosinase enzyme. However, it can cause skin irritation, allergy, dermatitis and, in the case of chronic use, exogenous ochronosis, characterized as a rare bluish-black dermatosis.[6,7] There are other treatments, for example, kojic acid and azelaic acid as tyrosinase inhibitors, chemical peels, and laser therapy, in the place of the widely used hydroquinone. However, they also have limitations and undesirable effects. Kojic acid and azelaic acid have difficulty reaching the epidermis and they require long periods of treatment.[8] Furthermore, kojic acid, as a well-known ingredient for skin depigmentation, is unstable during the storage, has limited tyrosinase inhibitory activity, and may cause contact dermatitis and, over a long period, photodamaged skin.[9,10] Lastly, laser therapy and chemical peels have a high safety risk, with the possibility of inflammation, scarring, changes in skin color, or even rebound hyperpigmentation.[8,11]