Isolation and Tyrosinase Inhibitory Effects of Polyphenols from the Leaves of Persimmon, Diospyros kaki

Abstract

The main polyphenols were isolated from the leaves of six selected persimmon cultivars. Seven compounds were obtained by reverse-phase HPLC, and their structures were elucidated by multiple NMR measurements. These compounds are hyperoside, isoquercitrin, trifolin, astragalin, chrysontemin, quercetin-3-O-(2''-O-galloyl-β-D-glucopyranoside) (QOG), and kaempferol-3-O-(2''-O-galloyl-β-D-glucopyranoside) (KOG). Their inhibitory activity was tested against tyrosinase for the oxidation of L-DOPA, and only chrysontemin showed inhibitory activity. To investigate the differences of their inhibitory effects, the tyrosinase inhibitory activities of their aglycons, cyanidin, quercetin, and kaempferol, were also tested. As a result, it was confirmed that the most influential moiety for tyrosinase inhibition was the 3',4'-dihydroxy groups of the catechol moiety. Moreover, the tyrosinase inhibitory activity of chrysontemin, which was identified in persimmon leaves for the first time, is supported by a simulated model of chrysontemin docking into mushroom tyrosinase.

Hyperoside and rutin of Nelumbo nucifera induce mitochondrial apoptosis through a caspase-dependent mechanism in HT-29 human colon cancer cells

“…The roots of N. nucifera have been identified as being rich in dietary fiber, vitamins B1, B2, B6 and C, potassium, phosphorus, copper and manganese (10). N. nucifera contains biologically effective flavonoids, including kaempferol, quercetin, rutin and hyperoside, exhibits anti-inflammatory, -oxidant, -fungal, -microbial and tyrosinase inhibitory activities, and has protective properties in carbon tetrachloride-induced liver damage (11)(12)(13)(14)(15)(16)(17)(18).…”

Antihypertensive activity of a quinoline appended chalcone derivative and its site specific binding interaction with a relevant target carrier protein

“…So the inhibition of ACE has been used as one of the methods for the treatment of hypertension related to cardiovascular disorders and congestive heart failure. Inhibitory constant 27,28 obtained is found to be of the order of 167.19 M (Fig1b). The colour formed has been measured at 410 nm in ELISA plate reader.…”

Extraction, partial purification and characterisation of vanillic acid decarboxylase fromAlicyclobacillus acidoterrestrisDSM 3923

“…When the concentration increased to 1.0 mmol L −1 , VAD activity was completely inhibited by cinnamic acid, ferulic acid, resveratrol, quercetin and rutin. Polyphenols, especially flavonoids, were described to inhibit numerous unrelated enzymes . The inhibition mechanism may be due to the binding of these molecules to enzymes through hydrogen bonding, hydrophobic interactions, metal chelation and ππ ‐stacking …”