A new anthraquinone glycoside from Rhamnus nakaharai and anti-tyrosinase effect of 6-methoxysorigenin

Abstract

In continual study on the heartwood of Rhamnus nakaharai, a new alaternin-8-O-glucoside, namely 1,2,6,8-tetrahydroxy-3-methylanthraquinone-8-O-β-glucopyranoside (1), together with some known compounds were further isolated and characterised by 1-D, 2-D NMR and other spectral evidences. The free radical scavenging and antityrosinase activities of the isolates, including alaternin (1a), emodin (2a), emodin-8-O-β-glucopyranoside (2), 6-methoxysorigenin-8-O-β-glucopyranoside (3) and 6-methoxysorigenin (3a) were tested. Alaternin (1a) exhibited to be mild DPPH radical scavenger with half as potent as vitamin C, while both alaternin (1a) and emodin-8-O-β-glucopyranoside (2) exhibited stronger SOD-like activity than that of BHA. 6-Methoxysorigenin (3a), a reported potential antioxidant, and its 8-O-glucoside (3) both performed significant inhibitory effect on mushroom tyrosinase with about twice as potent as kojic acid, the positive control.

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

“…Low IC50 values against both monophenolase and diphenolase activty of mushroom tyrosinase have been very recently reported for p-coumaric and caffeic acid [66], belonging to the cinammic acid family ( Figure 7). The IC50 values together with structural formulas for other phenolic compounds widely distributed in nature that have been the subject of studies that appeared in the last five years [53,62,63,[67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82] Low IC 50 values against both monophenolase and diphenolase activty of mushroom tyrosinase have been very recently reported for p-coumaric and caffeic acid [66], belonging to the cinammic acid family ( Figure 7). Moving to simple phenols, significant inhibition activity has been described for 4-hydroxybenzyl alcohol (IC50 = 6 μM) [61] and isoeugenol (IC50 = 33.3 μM) [62], which would appear more efficient than resorcinol [55] or rhododendrol [63] themselves.…”

“…Low IC50 values against both monophenolase and diphenolase activty of mushroom tyrosinase have been very recently reported for p-coumaric and caffeic acid [66], belonging to the cinammic acid family (Figure 7). The IC50 values together with structural formulas for other phenolic compounds widely distributed in nature that have been the subject of studies that appeared in the last five years [53,62,63,[67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82] The IC 50 values together with structural formulas for other phenolic compounds widely distributed in nature that have been the subject of studies that appeared in the last five years [53,62,63,[67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82] are also reported in Figures 4-8.…”

Traditional Medicinal Uses, Phytochemicals, and Pharmacological Activities of Genus Rhamnus: A review

“…A prominent anti-tyrosinase effect was displayed by 6-methoxysorigenin ( 12) reported from R. nakaharai with IC50 vaue of 42.2 μM, which was twofold more potent than kojic acid with IC50 value of 82.1 μM (70). In a related study, antioxidant alaternin ( 10) was reported from R. nakaharai with IC50 value of 117.7 μM compared to ascorbic acid (IC50 value of 63.7 μM) using DPPH assay method (70).…”

Rhamnus alaternus Plant: Extraction of Bioactive Fractions and Evaluation of Their Pharmacological and Phytochemical Properties

“…This former experiment was carried out with two strains of Salmonella Typhimurium (i.e., TA98 and TA100) in the presence of various extracts, and spontaneous revertant was used as control. Petroleum ether, chloroform, methanol, aqueous, and total oligomers flavonoids (TOF) extracts obtained by R. alaternus maceration were investigated at various doses (10,50, and 250 µg/plate) and remarkably reduced the AFB1-induced mutagenicity. In this study, the ethyl acetate fraction obtained from the R. alaternus aqueous extract was the most effective at a dose of 250 µg/plate.…”

“…Indeed, these sources of natural compounds possess pharmacological activities, and are used for their curative effects to treat some symptoms and diseases [1][2][3][4][5][6][7]. During the past few years, several studies highlighted the potential efficacy of Rhamnus species in many areas [8][9][10][11]. Among these naturally available species, the Rhamnus alaternus plant (R. alaternus) is commonly recognized as a 5-meter-tall shrub, and is distributed throughout the Mediterranean area [12][13][14][15] including North Algeria, Tunisia, and Morocco [16,17].…”