Melanogenesis is a process responsible for melanin production, which is stored in melanocytes containing tyrosinase. Inhibition of this enzyme is a target in the cosmetics industry, since it controls undesirable skin conditions such as hyperpigmentation due to the overproduction of melanin. Species of the Morus genus are known for the beneficial uses offered in different parts of its plants, including tyrosinase inhibition. Thus, this project aimed to study the inhibitory activity of tyrosinase by extracts from Morus nigra leaves as well as the characterization of its chromatographic profile and cytotoxicity in order to become a new therapeutic option from a natural source. M. nigra leaves were collected, pulverized, equally divided into five batches and the standardized extract was obtained by passive maceration. There was no significant difference between batches for total solids content, yield and moisture content, which shows good reproducibility of the extraction process. Tyrosinase enzymatic activity was determined for each batch, providing the percentage of enzyme inhibition and IC50 values obtained by constructing dose-response curves and compared to kojic acid, a well-known tyrosinase inhibitor. High inhibition of tyrosinase activity was observed (above 90% at 15.625 μg/mL). The obtained IC50 values ranged from 5.00 μg/mL ± 0.23 to 8.49 μg/mL ± 0.59 and were compared to kojic acid (3.37 μg/mL ± 0.65). High Performance Liquid Chromatography analysis revealed the presence of chlorogenic acid, rutin and, its major compound, isoquercitrin. The chromatographic method employed was validated according to ICH guidelines and the extract was standardized using these polyphenols as markers. Cytotoxicity, assessed by MTT assay, was not observed on murine melanomas, human keratinocytes and mouse fibroblasts in tyrosinase IC50 values. This study demonstrated the potential of M. nigra leaf extract as a promising whitening agent of natural source against skin hyperpigmentation.
A preliminary dietary exposure assessment for aflatoxins (AFs; AFB1, AFB2, AFG1 and AFG2) was conducted to evaluate the potential carcinogenic risks for the Brazilian population. AF concentration data in food were obtained from analysis reports issued by the Central Public Health Laboratory of the Federal District (LACEN-DF) and from published work. Food consumption and body weight (bw) data were obtained from a national survey conducted in 2008/2009. Cancer risks arising from exposure to aflatoxins were assessed using the carcinogenic potency of AFs estimated by the JECFA, and hepatitis B virus prevalence in the Brazilian population. Additionally, margins of exposure (MOE) were also calculated for the various scenarios investigated. A total of 942 food samples were analysed for AFs in the Federal District between 2002 and 2011 with 4.5% of them being positive for at least one aflatoxin (LOQ = 2 µg kg(-1)). The highest percentage of contamination was found in peanuts (8.1%) and Brazil nuts (6.0%), with mean levels ranging from 6.7 µg kg(-1) in peanut products to 36.9 µg kg(-1) in Brazil nuts. Most of the studies conducted elsewhere in Brazil found similar results. Total AF intake for the total Brazilian population and high consumers of food relevant for AF contamination in Brazil (upper bound; samples < LOQ = 0.5 LOQ) were 6.8 and 27.6 ng kg(-1) bw day(-1), respectively. Cancer risk reached 0.0753 cancers year(-1) per 10(5) individuals for the total population and 0.3056 cancers year(-1) per 10(5) individuals for high consumers. MOE reached 25 and 6 for the total population and high consumers, respectively, indicating a potential risk for consumers. Aflatoxins are genotoxic carcinogens, and government action should be maintained and continuously improved in order to guarantee that human exposure levels are kept as low as possible.
Degradation products are impurities resulting from chemical changes that occur during drug manufacturing. They can also form during storage and transportation in response to changes in light, temperature, pH, and humidity, or due to inherent characteristics of the active pharmaceutical substance, such as their reaction with excipients or on contact with the packaging. The presence of these chemicals can affect product safety and quality. Therefore, it is necessary to know and follow the guidelines and standards regarding degradation products and existing regulatory environments to assess the toxicity and risk related to their presence in pharmaceutical products.
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