In‐vitro effect of pine bark extract on melanin synthesis, tyrosinase activity, production of endothelin‐1 and PPAR in cultured melanocytes exposed to Ultraviolet, Infrared, and Visible light radiation

AbstractA modified in vitro lipid peroxidation inhibition assay was used to guide the fractionation and the isolation of antioxidative principles of Finnish pine bark extract. This approach yielded 3,4-dihydroxybenzoic acid (protocatechuic acid) and taxifolin-3-O-β-glucopyranoside as major antioxidative compounds from the plant material. The structural elucidation of these compounds was undertaken with the help of HPLC-DAD and HPLC-ESI-MS analyses. Their IC50 values, in comparison to trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), were: trolox (1.78 ± 0.56 μm) < protocatechuic acid (5.77 ± 1.63 μm) < taxifolin-3- O-β-glucopyranoside (16.30 ± 1.98 μm). The method for the determination of antioxidant activity proved reproducible and quick for routine analyses with 96 well plates.

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In vitro effect of endothelin-1 and nifedipine on pulmonary vascular contraction of pulmonary hypertensive and non-pulmonary hypertensive chickens

Journal of Applied Animal Research ◽

10.1080/09712119.2015.1125355 ◽

2016 ◽

Vol 45 (1) ◽

pp. 256-262

Author(s):

Rocío Rincón ◽

Aureliano Hernández ◽

Camilo Orozco

Keyword(s):

Vascular Contraction ◽

Endothelin 1 ◽

Vitro Effect

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THE MELANOGENIC RESPONSE TO TESTOSTERONE IN SCROTAL EPIDERMIS: EFFECTS ON TYROSINASE ACTIVITY AND PROTEIN SYNTHESIS

Acta Endocrinologica ◽

10.1530/acta.0.0810435 ◽

1976 ◽

Vol 81 (2) ◽

pp. 435-448 ◽

Cited By ~ 12

Author(s):

Michael J. Wilson ◽

Eugene Spaziani

Keyword(s):

Protein Synthesis ◽

Specific Protein ◽

Tyrosinase Activity ◽

Melanin Synthesis ◽

Testosterone Treatment ◽

Pre Treatment ◽

Inhibitor Of Protein Synthesis ◽

Rate Limiting

ABSTRACT Pigmentation of the scrotum of the black-pelted rat, as expressed through melanocyte melanogenic activity, is controlled by androgens. Castration decreased in vitro incorporation of [14C] tyrosine into melanin. Testosterone pre-treatment for 4 days increased melanin radioactivity over castrate controls; the increment in vitro was prevented by an inhibitor of protein synthesis (cycloheximide) added to the incubation. However, cycloheximide only partially blocked melanin synthesis when added to tissue from animals hormone treated for 6 days in vivo, and was ineffective in tissue from intacts. Bulk protein synthesis in vitro (incorporation of [14C] tyrosine or -leucine) was not affected by castration or testosterone treatment but was uniformly inhibited by cycloheximide. The data suggest that new synthesis of specific protein in vitro was necessary for initial hormone-stimulation of melanogenesis, but with longer exposure to hormone sufficient protein was pre-synthetized in vivo to permit melanogenesis during incubation with the inhibitor. Radioautographs of epidermis incubated with [14C] tyrosine showed grains concentrated over macromolecular aggregates in melanocytes, a pattern not altered by cycloheximide. Though available for incorporation into general tissue protein. [14C] tyrosine was apparently incorporated preferentially into melanin by melanocytes. DOPA (3,4-dihydroxyphenylalanine) added to incubations in cofactor amounts did not affect decreased melanin synthesis after castration and appears, therefore, not to be rate limiting in that decrease. Tissue uptake of free [14C] tyrosine or — leucine during incubation was lower than normal in castrate epidermis; uptake was elevated by testosterone treatment. Concentrations appeared sufficient in all preparations to suggest that availability is not rate limiting for synthesis of melanin or protein; however, a possible influence on amino acid permeability for melanocytes remains undetermined. Tyrosinase activity was present in both particulate and cytosol fractions of epidermis but decreased significantly after castration only in the cytosol. Testosterone increased particulate activity after 4 days and soluble activity after 9 days of treatment. These and findings above are consistent with a model that tyrosinase is synthesized and incorporated into melanosome structure within 4 days testosterone treatment; with longer treatment synthesis may then exceed that required for melanosome assembly and tyrosinase appears in the soluble milieu.

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Attenuation of In Vitro and In Vivo Melanin Synthesis using a Chinese Herbal Medicine through the Inhibition of Tyrosinase Activity

Phytomedicine ◽

10.1016/j.phymed.2021.153876 ◽

2021 ◽

pp. 153876

Author(s):

Shu-Chun Liu ◽

Meei-Ling Sheu ◽

Yi-Ching Tsai ◽

Yu-Chin Lin ◽

Ching-Wen Chang ◽

...

Keyword(s):

Herbal Medicine ◽

Chinese Herbal Medicine ◽

Tyrosinase Activity ◽

Melanin Synthesis ◽

Chinese Herbal

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In vitro effect of endothelin-1 on collagen, and ADP-induced aggregation in human whole blood and platelet rich plasma

Thrombosis Research ◽

10.1016/0049-3848(95)90866-e ◽

1995 ◽

Vol 77 (1) ◽

pp. 69-78 ◽

Cited By ~ 20

Author(s):

Ralf Knöfler ◽

Tetsumei Urano ◽

Jolanta Malyszko ◽

Yumiko Takada ◽

Akikazu Takada

Keyword(s):

Whole Blood ◽

Platelet Rich Plasma ◽

Human Whole Blood ◽

Endothelin 1 ◽

Vitro Effect ◽

Induced Aggregation

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Ultraviolet radiation and melanogenesis

Archive of oncology ◽

10.2298/aoo0404203s ◽

2004 ◽

Vol 12 (4) ◽

pp. 203-205 ◽

Cited By ~ 6

Author(s):

Milenko Stanojevic ◽

Zorica Stanojevic ◽

Dragan Jovanovic ◽

Milena Stojiljkovic

Keyword(s):

Free Radicals ◽

Visible Light ◽

Uv Radiation ◽

Infrared Radiation ◽

Biological Effects ◽

Radiation Energy ◽

Light Radiation ◽

Melanin Synthesis ◽

Protection Mechanisms

Light radiation is a part of the electromagnetic radiation, and it consists of the ultraviolet (UV) radiation, visible light, and infrared radiation. UV radiation energy is absorbed in the form of photons in biomolecules (chromophores) and induces various cellular reactions, out of which photochemical and photosensitizing are the most significant. In contact with the skin UV radiation incites protection mechanisms: the most important are stratum corneum thickening and melanin synthesis (melanogenesis). Basic role of melanin is absorption and scattering of UV rays and neutralization of free radicals. In this review physical characteristics of UV radiation, its biological effects, and relation to melanogenesis and carcinogenesis are discussed.

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Evaluation of the Novel Synthetic Tyrosinase Inhibitor (Z)-3-(3-bromo-4-hydroxybenzylidene)thiochroman-4-one (MHY1498) In Vitro and In Silico

Molecules ◽

10.3390/molecules23123307 ◽

2018 ◽

Vol 23 (12) ◽

pp. 3307 ◽

Cited By ~ 3

Author(s):

EunJin Bang ◽

Sang-Gyun Noh ◽

Sugyeong Ha ◽

Hee Jung ◽

Dae Kim ◽

...

Keyword(s):

In Silico ◽

Docking Simulation ◽

Positive Control ◽

Tyrosinase Activity ◽

Inhibition Mechanism ◽

The Novel ◽

Melanin Synthesis ◽

Chemical Structures ◽

Tyrosinase Inhibitors

Tyrosinase is a key enzyme in melanin synthesis, catalyzing the initial rate-limiting steps of melanin synthesis. Abnormal and excessive melanin synthesis is the primary cause of serious skin disorders including melasma, senile lentigo, freckles, and age spots. In attempts to find potent and safe tyrosinase inhibitors, we designed and synthesized a novel compound, (Z)-3-(3-bromo-4-hydroxybenzylidene)thiochroman-4-one (MHY1498), and evaluated its tyrosinase inhibitory activity in vitro and in silico. The chemical structures of (Z)-3-benzylidenethiochroman-4-one analogues, including the novel compound MHY1498, were rationally designed and synthesized as hybrid structures of reported potent tyrosinase inhibitors, which were confirmed both in vitro and in vivo: (Z)-5-(substituted benzylidene)thiazolidine-2,4-diones (Compound A) and 2-(substituted phenyl)benzo[d]thiazoles (Compound B). During screening, MHY1498 showed a strong dose-dependent inhibitory effect on mushroom tyrosinase. The IC50 value of MHY1498 (4.1 ± 0.6 μM) was significantly lower than that of the positive control, kojic acid (22.0 ± 4.7 μM). In silico molecular multi-docking simulation and inhibition mechanism studies indicated that MHY1498 interacts competitively with the tyrosinase enzyme, with greater affinity for the active site of tyrosinase than the positive control. Furthermore, in B16F10 melanoma cells treated with α-melanocyte-stimulating hormone, MHY1498 suppressed both melanin production and tyrosinase activity. In conclusion, our data demonstrate that MHY1498, a synthesized novel compound, effectively inhibits tyrosinase activity and has potential for treating hyperpigmentation and related disorders.

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Pine Bark Polyphenolic Extract Attenuates Amyloid-β and Tau Misfolding in a Model System of Alzheimer’s Disease Neuropathology1

Journal of Alzheimer s Disease ◽

10.3233/jad-190543 ◽

2020 ◽

Vol 73 (4) ◽

pp. 1597-1606

Author(s):

Kenjiro Ono ◽

Daisy Zhao ◽

Qingli Wu ◽

James Simon ◽

Jun Wang ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Biological Activities ◽

Amyloid Β ◽

Polyphenolic Compounds ◽

Pine Bark ◽

Bark Extract ◽

Amyloid Β Protein ◽

Polyphenolic Extract

Plant-derived polyphenolic compounds possess diverse biological activities, including strong anti-oxidant, anti-inflammatory, anti-microbial, and anti-tumorigenic activities. There is a growing interest in the development of polyphenolic compounds for preventing and treating chronic and degenerative diseases, such as cardiovascular disorders, cancer, and neurological diseases including Alzheimer’s disease (AD). Two neuropathological changes of AD are the appearance of neurofibrillary tangles containing tau and extracellular amyloid deposits containing amyloid-β protein (Aβ). Our laboratory and others have found that polyphenolic preparations rich in proanthocyanidins, such as grape seed extract, are capable of attenuating cognitive deterioration and reducing brain neuropathology in animal models of AD. Oligopin is a pine bark extract composed of low molecular weight proanthocyanidins oligomers (LMW-PAOs), including flavan-3-ol units such as catechin (C) and epicatechin (EC). Based on the ability of its various components to confer resilience to the onset of AD, we tested whether oligopin can specifically prevent or attenuate the progression of AD dementia preclinically. We also explored the underlying mechanism(s) through which oligopin may exert its biological activities. Oligopin inhibited oligomer formation of not only Aβ1-40 and Aβ1-42, but also tau in vitro. Our pharmacokinetics analysis of metabolite accumulation in vivo resulted in the identification of Me-EC-O-β-Glucuronide, Me-(±)-C-O-β-glucuronide, EC-O-β-glucuronide, and (±)-C-O-β-glucuronide in the plasma of mice. These metabolites are primarily methylated and glucuronidated C and EC conjugates. The studies conducted provide the necessary impetus to design future clinical trials with bioactive oligopin to prevent both prodromal and residual forms of AD.

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