Proanthocyanidins Extracted from Rhododendron pulchrum Leaves as Source of Tyrosinase Inhibitors: Structure, Activity, and Mechanism

Abstract

The objective of this study was to assess the structure, anti-tyrosinase activity, and mechanism of proanthocyanidins extracted from Rhododendron pulchrum leaves. Results obtained from mass spectra of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS) revealed that proanthocyanidins were complex mixtures of procyanidins, prodelphinidins, propelargonidins, and their derivatives, among which procyanidins were the main components. The anti-tyrosinase analysis results indicated that the mixtures were reversible and mixed competitive inhibitors of tyrosinase. Interactions between proanthocyanidins with substrate (L-tyrosine and 3,4-dihydroxyphenylalanine) and with copper ions were the important molecular mechanisms for explaining their efficient inhibition. This research would provide scientific evidence for the use of R. pulchrum leaf proanthocyanidins as new novel tyrosinase inhibitors.

Activity, Purification, and Analysis of Condensed Tannins: Current State of Affairs and Future Endeavors

“…6 and is similar to the illustration provided in a published disclosure depicting a proteinhydrolyzable tannin complex (Spencer et al, 1988). These schematic representations are supported by recent computational experiments between oligopeptides (Simon et al, 2003) or proteins such as tyrosinase (Chai et al, 2015) and CTs. Molecular dynamics calculation of flavan-3-ols and CT dimers and trimers with polyvinylproline (PVP) shows association through both hydrophobic and hydrogen bonding interactions and that adsorption occurs not only on the PVP surface but also by binding into pockets of the PVP polymer (Gil et al, 2017).…”

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

“…On the contrary, biflavonoids not containing a 1,3-benzenediol from Solanum nigrum (Figure 11) were only poor tyrosinase inhibitos, with IC 50 values > 190 µM [94]. Increasing attention has been devoted to condensed tannins, which have shown promising activities as inhibitors of both monophenolase and diphenolase activity of mushroom tyrosinase (Table 1) [96][97][98][99][100][101][102][103][104][105][106][107]. Particularly active were prodelphinidins and procyanidins from the fruit pericarp of Clausena lansium Skeels [102], as well as the complex mixtures isolated from Persea Americana [106], Longan bark [99], and from leaves and fruit of Leucaena leucocephala [97].…”

Novel Insights into the Inhibitory Effect and Mechanism of Proanthocyanidins from Pyracantha fortuneana Fruit on α‐Glucosidase

“…Mixtures of oligomers and polymers consist of flavan‐3‐ol monomer units linked principally via C4‐C8 or C4‐C6 bonds (B‐type), occasionally, through a C4‐C8 linkage with an additional C2‐O7 linkage (A‐type) (Figure ) (Kennedy and Taylor ). Proanthocyanidins endowed with rich pharmacological properties and biological activities, which have been reported to possess anti‐microbial (Ho and others ), anti‐cancer (Zhang and others ), anti‐viral (Bagchi and others ), antioxidant (Škerget and others ), anti‐hyperpigmentation (Chai and others ) and neuroprotection activities (Aron and Kennedy ). Hence, proanthocyanidins have aroused considerable interest and received increasingly attention in recent years (Chai and others , 2014, ; Fu and others ).…”