title: Extracts of Morus nigra L. Leaves Standardized in Chlorogenic Acid, Rutin and Isoquercitrin: Tyrosinase Inhibition and Cytotoxicity.
abstract: 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.
authors.affiliation: Department of Pharmacy, Health Sciences School, University of Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Marcela Medeiros
authors.identifier: http://orcid.org/0000-0002-6112-9903
authors.initials: MM
authors.lastname: de Freitas
authors.affiliation: Department of Pharmacy, Health Sciences School, University of Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Pedro Ribeiro
authors.initials: PR
authors.lastname: Fontes
authors.affiliation: Department of Pharmacy, Health Sciences School, University of Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Paula Monteiro
authors.initials: PM
authors.lastname: Souza
authors.affiliation: Department of Botany, Institute of Biological Science, School of Pharmacy, Ceilândia Campus, University of Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Christopher
authors.initials: C
authors.lastname: William Fagg
authors.affiliation: Department of Odontology, Health Sciences School, University of Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Eliete
authors.initials: E
authors.lastname: Neves Silva Guerra
authors.affiliation: Immunogenetic and Chronic-degenerative Diseases Laboratory, School of Medicine, University of Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Yanna Karla
authors.initials: YK
authors.lastname: de Medeiros Nóbrega
authors.affiliation: Department of Pharmacy, Health Sciences School, University of Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Damaris
authors.initials: D
authors.lastname: Silveira
authors.affiliation: Department of Pharmacy, Health Sciences School, University of Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Yris
authors.initials: Y
authors.lastname: Fonseca-Bazzo
authors.affiliation: Department of Pharmacy, Health Sciences School, University of Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Luiz Alberto
authors.initials: LA
authors.lastname: Simeoni
authors.affiliation: Department of Pharmacy, Health Sciences School, University of Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Maurício
authors.initials: M
authors.lastname: Homem-de-Mello
authors.affiliation: Department of Pharmacy, Health Sciences School, University of Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Pérola
authors.initials: P
authors.lastname: Oliveira Magalhães