Condensed Tannins from Longan Bark as Inhibitor of Tyrosinase: Structure, Activity, and Mechanism

Abstract

In this study, the content, structure, antityrosinase activity, and mechanism of longan bark condensed tannins were evaluated. The findings obtained from mass spectrometry demonstrated that longan bark condensed tannins were mixtures of procyanidins, propelargonidins, prodelphinidins, and their acyl derivatives (galloyl and p-hydroxybenzoate). The enzyme analysis indicated that these mixtures were efficient, reversible, and mixed (competitive is dominant) inhibitor of tyrosinase. What's more, the mixtures showed good inhibitions on proliferation, intracellular enzyme activity and melanogenesis of mouse melanoma cells (B). From molecular docking, the results showed the interactions between inhibitors and tyrosinase were driven by hydrogen bond, electrostatic, and hydrophobic interactions. In addition, high levels of total phenolic and extractable condensed tannins suggested that longan bark might be a good source of tyrosinase inhibitor. This study would offer theoretical basis for the development of longan bark condensed tannins as novel food preservatives and medicines of skin diseases.

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

“…Several inhibition mechanisms have been reported for the tyrosinase inhibitors described above, highlighting the importance of key structural moieties as responsible for the observed effects. As an example, in silico analysis showed that the flavonoids spinosin and swertiajaponin act as competitive inhibitors of the enzyme by binding to the active site through hydrogen bonding and hydrophobic interactions [212,214], as is the case also for condensed tannins from different sources based on molecular docking [96,98,99]. Chelation of copper ions by adjacent hydroxyl groups on the B ring has also been suggested as a feasible inhibition mechanism for proanthocyanidins [101,102,106].…”

“…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]. Very potent (IC 50 values in the range 0.10-7.5 µM) mushroom tyrosinase inhibitors have been isolated from licorice (Figure 12), the most active belonging to the isoflavan class [108][109][110] IC50 values in the range 28-42 μM have been reported for two lignans isolated from Opilia amentacea leaves [112] (Figure 13), whereas particularly effective against the monophenolase activity of the enzyme were flavonolignans from the seeds of Silybum marianum (IC50 in the range 1.7-4.9 μM) ( Figure 13) [113] as well as, although with a lower strength, hydroxylated phenones from Syzygium polyanthum leaves [114] (Figure 14).…”

“…In the last five years, several natural and synthetic phenolic compounds have been described also as inhibitors of tyrosinase from animal and human sources. Most of these studies used B16 murine melanoma cell lines as a model [52,55,75,85,95,96,99,114,122,123,[127][128][129][132][133][134][135]138,139,151,153,155,163,, although some papers using zebrafish as an in vivo whole animal model have also been published [55,116,206]. As to the human sources, data on inhibition of human recombinant or purified tyrosinase [9,207], human melanoma cells [130,136], normal human melanocytes [208][209][210][211], or human skin models consisting of reconstructed three-dimensional human epidermis [212][213][214][215] have been published (Figure 21).…”

Tyrosinase Inhibitors from Natural and Synthetic Sources as Skin-lightening Agents

“…This study group suggested that, the condensed tannins could be used to design and screen for potent novel tyrosinase inhibitors. Recently, another study (Chai et al, 2018) suggested that condensed tannins from longan bark might be a good source of tyrosinase inhibitor and could be used as novel food preservatives and medicines of skin diseases. Results showed good inhibitions on proliferation, intracellular enzyme activity and melanogenesis of mouse melanoma cells.…”

Simultaneous Determination of Six Isoflavones from Puerariae Lobatae Radix by CPE-HPLC and Effect of Puerarin on Tyrosinase Activity

“…Tyrosinase expression is closely related to many physiological functions in animals. If its function is decreased or deleted, it will lead to depigmentation diseases, such as vitiligo and leukosis [4,5], while autosomal recessive diseases in animals and humans such as Parkinson's disease are also related to tyrosinase deletion or activity decreases [6][7][8]. In addition, abnormal overexpression of its activity will lead to pigmentation diseases of the human body, such as freckles, chloasma and melanoma [9][10][11][12].…”