Extract from Ceratonia siliqua Exhibits Depigmentation Properties

Abstract

Skin hyper-pigmentation is a condition initiated by the overproduction of melanin existing in the melanocytes. Melanin pigment is responsible for the colour of skin in humans. It is formed through a series of oxidative reactions involving the amino acid tyrosine in the presence of the key enzyme tyrosinase. In continuation with our efforts to identify tyrosinase inhibitors from plants sources, the methanol extract from leaf, bark and fruit of Ceratonia siliqua were screened for tyrosinase inhibition and diphenolase activity. The bark extract exhibited significant inhibition on mushroom tyrosinase using L-tyrosine as a substrate and showed diphenolase activity. The extract further significantly lowered tyrosinase mRNA levels in B16-F10 mouse melanocytes. Bioassay-guided fractionation led to the isolation of six compounds. Compounds (-)-epicatechin-3-O-gallate, 1,2,3,6-tetra-O-galloyl-ß-D-glucose and gallocatechin-3-O-gallate showed tyrosinase inhibitions with the IC50 values of 27.52, 83.30 and 28.30 µg/mL, respectively. These compounds also exhibited L-DOPA activities with IC50 values of >200, 150 and 200 µg/mL, respectively. A clinical study was conducted using 20 volunteers in a patch testing trial for irritancy potential and skin depigmentation. The clinical results showed the sample to be non-irritant with irritancy potential of -34.21 and depigmentation trial showed an improvement in the even skin tone of UV induced pigmentation at 3% after 28 days of application.

Biological Activities of Ceratonia siliqua Pod and Seed Extracts: A Comparative Analysis of Two Cretan Cultivars

“…A similar though less intense inhibitory activity against tyrosinase has been reported for a Turkish carob ethanolic seed extract [79]. In a previous study of the antimelanogenic properties of C. siliqua ethanolic leaf, bark, and fruit extracts, monophenolase activity was found to be potently inhibited by all extracts, while diphenolase activity was inhibited mainly by the leaf extract [80], in agreement with our observations regarding the aqueous methanolic leaf extract from the Imera cultivar (Elounda; Table S3). Comparable inhibitory effects have been also reported with carob leaf methanolic and aqueous extracts from Turkish plants [56].…”

Natural and synthetic flavonoid derivatives as new potential tyrosinase inhibitors: a systematic review

“…Moreover, it was reported that three 3-hydroxyavones including kaempferol, galangin, and quercetin inhibit the L-DOPA oxidation process catalyzed by tyrosinase, and apparently, this TI activity arises from their Cu 2+ chelating ability. [161][162][163][164][165][166] Kubo et al assumed that the chelation mechanism by avonols may be attributed to the free 3-OH group. Remarkably, quercetin acts as a cofactor and does not inhibit monophenolase activity.…”

Natural and Bioinspired Phenolic Compounds as Tyrosinase Inhibitors for the Treatment of Skin Hyperpigmentation: Recent Advances

“…A significant melanogenesis inhibition potential has been reported also for galangin (IC 50 = 3.55 µM) [52], isoliquiritigenin (IC 50 = 4.85 µM) [53], kaempferol (IC 50 = 5.5 µM) [54], and dihydromorin (IC 50 = 9.4 µM) [55], belonging to different flavonoid subfamilies, but all characterized by at least one resorcinol moiety. IC50 values in the range 20-150 µM have instead been reported for catechins [56][57][58][59]. Among natural phenolic compounds acting as tyrosinase inhibitors (Supplementary Materials, Table S1), flavonoids are the most representative class.…”