Compounds with Tyrosinase Inhibition, Elastase Inhibition and DPPH Radical Scavenging Activities from the Branches of Distylium racemosum Sieb. et Zucc

Abstract

Twenty compounds were isolated from the ethanol extract of Distylium racemosum branches and their inhibitory activities on tyrosinase, elastase and free radicals evaluated. The isolated compounds were identified as dibenzofurans (1-4), abscisic acid (5), 6'-O-galloylsalidroside (6), catechin derivatives (7-11), gallic acid derivatives (12-14), tyrosol (15), flavonoids (16-18), lupeol (19) and 1,2,3,6-tetragalloylglucose (20). For study of tyrosinase inhibition activities, when compared with arbutin (IC(50) 48.8 μg/mL), four compounds (8, 11, 13, 17) showed higher activities, with IC(50) values of 4.8, 30.2, 40.5 and 37.7 μg/mL, respectively. For the elastase inhibition test, dibenzofuran 1 showed greater activity than the positive control, oleanolic acid (IC(50) 9.7 μg/mL), with an IC(50) of 7.7 μg/mL. In the studies on DPPH radical scavenging activities, five compounds (11, 12, 13, 14, 15) showed higher activities than ascorbic acid (IC(50) 5.0 μg/mL), with IC(50) values of 4.6, 3.9, 2.9, 3.8 and 4.7 μg/mL, respectively.

In vitro assessment of antioxidant activity of tyrosol, resveratrol and their acetylated derivatives

“…Chen, 313 Chan, Ho, Fung, & Wang, 1996). Surprisingly, tyrosol, with one aromatic hydroxyl 314 group, at a concentration range of 5-400µM, did not reveal any capacity to scavenge 315 free DPPH radicals, even though appropriate changes in diluents (70% ethanol or 316 DMSO or methanol), which had been suggested by other researchers, have also been 317 performed (Ko, Kim, Hyun, Jung & Lee, 2011;Malheiro, Sousa, Casal, Bento, & 318 Pereira, 2011). 319…”

Isolation of Flavonoids and Triterpenoids from the Fruits of Alphitonia Neocaledonica and Evaluation of their Anti‐oxidant, Anti‐tyrosinase and Cytotoxic Activities

“…All compounds ( 5–10 ) isolated from fractions F 3 –F 6 were tested at 1 mg/mL and no interesting activity was observed with the five flavonoids ( 5 – 9 ) (Table ), probably due to the glycosylation at C‐3, as observed previously with various flavonoids (Parvez et al ., ). Gallocatechin 10 inhibits 87.4% of the enzymatic activity, this activity has previously been demonstrated, with an IC 50 = 4.8 µg/mL (Ko et al ., ). Thus, the high anti‐tyrosinase activity of the n ‐butanol‐soluble part could be explained by the presence of tannins and/or catechin derivatives.…”

“…Flavonoids 5 , 6 and 8 have already demonstrated a DPPH radical scavenging activity with an IC 50 = 67.92 μM, 4.29 μM (Demirkiran et al ., ) and 26.4 μM (Tang et al ., ), respectively. Similarly, the DPPH radical scavenging activity of gallocatechin 10 has already been demonstrated with an IC 50 = 6.7 µg/mL (Ko et al ., ). These compounds are thus probably significantly involved in the DPPH radical scavenging activity of the n ‐butanol‐soluble part (EC 50 = 20 µg/mL).…”

Piper genus: source of natural products with anti-tyrosinase activity favored in phytocosmetics

“…Hydroxylation of L-tyrosine (tyrosine monophenolic activity) to 3,4-dihydroxy-phenylalanine (L-DOPA) and the oxidation of L-DOPA (diphenolase activity), to give dopaquinone. 5,6 The use of tyrosinase inhibitors such as kojic acid and hydroquinone is increasingly important in the cosmetic industry due to its anti-pigmentation effects. 7 Recent findings show that 4-n-butylresorcinol had the potential to acto as an effective depigmentation agent high better security profile than currently available agents.…”