“…1a). Similarly, the optimum PHL absorption was detected at a wavelength of 285 nm (Chen et al 2020). The optimum absorption peak followed the PHL trend than INS, an indication that the increase in absorbance of the INS-PHL mixture is dominantly influenced by PHL even though the PHL mole ratio is constant.…”
Diabetes is among the top ten deadly diseases in the world. It occurs either when the pancreas does not produce enough insulin (INS) or when the body cannot effectively use the insulin it produces. Phloretin (PHL) has a biological effect that can treat diabetes. A spectroscopic study was carried out to explore the interaction between phloretin and insulin. UV/Vis spectroscopy, fluorescence spectroscopy, and circular dichroism spectropolarimeter were used in the study. UV/Vis spectra showed that the interaction between PHL and INS produced strong absorption at a wavelength of 282 nm. The fluorescence analysis results showed that the excitation and emission occurred at 280-nm and 305-nm wavelengths, respectively. Temperature changes did not affect INS emissions. However, the interaction of PHL–INS caused a redshift at 305 to 317 nm. Temperature affected the binding constant (Ka) and the binding site (n). Ka decreased with increasing temperature and increased the binding site. The thermodynamic parameters such as enthalpy (ΔH0) and entropy (ΔS0) each had a value of − 16,514 kJ/mol and 22.65 J/mol·K. PHL and INS interaction formed hydrogen bonds and hydrophobic interaction. The free energy (ΔG0) recorded was negative. PHL and INS interactions took place spontaneously. The quenching effect was dynamic and static. KD values were greater than KS. The higher the temperature, the less was KD and KS. The appearance of two negative signals on circular dichroism (CD) spectropolarimeter implies that phloretin could induce regional configuration changes in insulin. The addition of PHL has revealed that the proportion of α-helix in the insulin stabilizes its structure. Phloretin’s stabilization and enhancement of the α-helix structural configuration in insulin indicate that phloretin can improve insulin resistance.
“…1a). Similarly, the optimum PHL absorption was detected at a wavelength of 285 nm (Chen et al 2020). The optimum absorption peak followed the PHL trend than INS, an indication that the increase in absorbance of the INS-PHL mixture is dominantly influenced by PHL even though the PHL mole ratio is constant.…”
Diabetes is among the top ten deadly diseases in the world. It occurs either when the pancreas does not produce enough insulin (INS) or when the body cannot effectively use the insulin it produces. Phloretin (PHL) has a biological effect that can treat diabetes. A spectroscopic study was carried out to explore the interaction between phloretin and insulin. UV/Vis spectroscopy, fluorescence spectroscopy, and circular dichroism spectropolarimeter were used in the study. UV/Vis spectra showed that the interaction between PHL and INS produced strong absorption at a wavelength of 282 nm. The fluorescence analysis results showed that the excitation and emission occurred at 280-nm and 305-nm wavelengths, respectively. Temperature changes did not affect INS emissions. However, the interaction of PHL–INS caused a redshift at 305 to 317 nm. Temperature affected the binding constant (Ka) and the binding site (n). Ka decreased with increasing temperature and increased the binding site. The thermodynamic parameters such as enthalpy (ΔH0) and entropy (ΔS0) each had a value of − 16,514 kJ/mol and 22.65 J/mol·K. PHL and INS interaction formed hydrogen bonds and hydrophobic interaction. The free energy (ΔG0) recorded was negative. PHL and INS interactions took place spontaneously. The quenching effect was dynamic and static. KD values were greater than KS. The higher the temperature, the less was KD and KS. The appearance of two negative signals on circular dichroism (CD) spectropolarimeter implies that phloretin could induce regional configuration changes in insulin. The addition of PHL has revealed that the proportion of α-helix in the insulin stabilizes its structure. Phloretin’s stabilization and enhancement of the α-helix structural configuration in insulin indicate that phloretin can improve insulin resistance.
“…The inhibition characteristic of tyrosinase is reversible inhibition. For the inhibition characterized by reversible inhibition, the combination of inhibitor and enzyme is a reversible dynamic equilibrium process [ [47] , [48] , [49] ]. Increasing the concentration of the inhibitor will cause the enzyme activity to decrease but the inhibitor only inhibits the enzyme activity rather than permanently inactivates the enzyme.…”
Section: Inhibitors Of Tyrosinasementioning
confidence: 99%
“…9 ) can bind to tyrosinase through a static process, which causes the conformation of tyrosinase to change, thereby inhibiting its activity. At the same time, In6 has a strong antioxidant capacity and the ability to reduce o -dopaquinone to l -DOPA [ 48 ]. Fig.…”
Tyrosinase is an important enzyme in controlling the formation of melanin in melanosome, and plays a key role in the pigmentation of hair and skin. The abnormal expression or activation of tyrosinase is associated with several diseases such as albinism, vitiligo, melanoma and Parkinson disease. Excessive deposition of melanin could cause diseases such as freckles and brown spots in the human body, and it is also closely related to browning of fruits and vegetables and insect molting. Detecting and inhibiting the activity of tyrosinase is of extraordinary value in the progress of diagnosis and treatment of these diseases. Therefore, many selective optical detection probes and small molecular inhibitors have been developed, and have made significant contributions to the basic and clinical research on these diseases. In this paper, the detection and inhibition of tyrosinase and their application in whitening products are reviewed, with special emphasis on development of fluorescent probes and inhibitors. Hopefully, this review will help design more efficient and sensitive tyrosinase probes and inhibitors, as well as shed light on novel treatment of diseases such as melanoma.
“…For example, although hydroquinone was reported to be an effective in vitro and in vivo tyrosinase inhibitor, it is unfortunately cytotoxic to melanocytes and has the side effect of hypopigmentation resulting in vitiligo (O' Donoghue, 2006;Manini et al, 2009). Natural products are one of the main sources in the search for tyrosinase inhibitors, where, for example, they have included caffeine from camellia pollen (Yuanfan et al, 2019), ellagic acid from nuts, soft fruits, and other plant tissues (Pitchakarn et al, 2013), and phloretin from apples (Chen et al, 2019a;Wang et al, 2018). Bee pollen has been reported to be an alternative source for potential nutritional and medical applications, since it exhibits many bioactivities, such as neurotoxicity protection and treatment (Ben Bacha et al, 2019), anti-inflammatory and antinociceptive activity (Lopes et al, 2019), and antibacterial and pro-regenerative effects (Schuh et al, 2019).…”
Background: Ozone deterioration in the atmosphere has become a severe problem causing overexposure of ultraviolet light, which results in humans in melanin overproduction and can lead to many diseases, such as skin cancer and melasma, as well as undesirable esthetic appearances, such as freckles and hyperpigmentation. Although many compounds inhibit melanin overproduction, some of them are cytotoxic, unstable, and can cause skin irritation. Thus, searching for new natural compounds with antityrosinase activity and less/no side effects is still required. Here, bee pollen derived from sunflower (Helianthus annuus L.) was evaluated. Materials and methods: Sunflower bee pollen (SBP) was collected from Apis mellifera bees in Lopburi province, Thailand in 2017, extracted by methanol and sequentially partitioned with hexane and dichloromethane (DCM). The in vitro antityrosinase activity was evaluated using mushroom tyrosinase and the half maximal inhibitory concentration (IC 50 ) is reported. The antioxidation activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and reported as the half maximal effective concentration. Two pure compounds with antityrosinase activity were isolated by silica gel 60 column chromatography (SG 60 CC) and high performance liquid chromatography (HPLC), and their chemical structure deduced by Nuclear Magnetic Resonance (NMR) analysis.
Results:The DCM partitioned extract of SBP (DCMSBP) had an antityrosinase activity (IC 50 , 159.4 μg/mL) and was fractionated by SG 60 CC, providing five fractions (DCMSBP1-5). The DCMSBP5 fraction was the most active (IC 50 ¼ 18.8 μg/mL) and further fractionation by HPLC gave two active fractions, revealed by NMR analysis to be safflospermidine A and B. Interestingly, both safflospermidine A and B had a higher antityrosinase activity (IC 50 of 13.8 and 31.8 μM, respectively) than kojic acid (IC 50 of 44.0 μM). However, fraction DCMSBP5 had no significant antioxidation activity, while fractions DCMSBP1-4 showed a lower antioxidation activity than ascorbic acid. Conclusion: Safflospermidine A and B are potential natural tyrosinase inhibitors.
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