Synthesis and investigation of anti-tyrosinase and antioxidant activity of new halogenated xanthone derivatives
Excess melanin production in skin cells promotes dermatological diseases such as hyperpigmentation, ageing, and other skin-related diseases. Tyrosinase enzyme catalyses the oxidation of L-tyrosine substrate to melanin, via formation of L-3,4- dihydroxyphenylalanine (L-DOPA). Thus, tyrosinase inhi...
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
2023
|
| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/118726/ http://psasir.upm.edu.my/id/eprint/118726/1/118726.pdf |
| Summary: | Excess melanin production in skin cells promotes dermatological diseases such as
hyperpigmentation, ageing, and other skin-related diseases. Tyrosinase enzyme
catalyses the oxidation of L-tyrosine substrate to melanin, via formation of L-3,4-
dihydroxyphenylalanine (L-DOPA). Thus, tyrosinase inhibitors can lower melanin
production to achieve whitening effect on the skin. Whitening products such as
hydroquinone and kojic acid that are commonly used nowadays, might be harmful to
human skin. This research aimed to produce 20 non-toxic halogenated tyrosinase
inhibitors synthetically using Grover-Shah and Shah (GSS) method and determine
their tyrosinase inhibitory activity using tyrosinase mushroom Agaricus bisporus assay
with kojic acid as positive control. Six compounds were found to inhibit the enzyme
with inhibition percentage of more than 50%. Among these six active compounds,
three compounds (15, 16 and 17) showed high potency. Their half-maximal inhibitory
concentration (IC50), enzyme kinetic analysis and antioxidant properties were
determined. The IC50 values for compounds 15 (7.8 μg/ml, 75 μg/ml), 16 (9 μg/ml,
118 μg/ml) and 17 (10 μg/ml, 100 μg/ml) in L-tyrosine and L-DOPA substrates
respectively, demonstrate their strong action in comparison to kojic acid as control
(IC50 4 μg/ml, 7.8 μg/ml). Enzyme kinetic analysis demonstrated that compounds 15
and 17 as uncompetitive inhibitor and compound 16 as mixed type inhibitor
respectively. In antioxidant assays, only compound 16 exhibited a high antioxidant
activity (IC50 18 μg/ml) in DPPH assay and 2.93 mM/g in FRAP assay with ascorbic
acid and quercetin as positive controls. Additionally, compound 16 revealed an IC50
value of 43.33 μM against the in vitro HaCaT skin cell line, indicating a weak toxicity
on human skin cells. Compound 16 also revealed a non-toxic property for screening of
toxicity test when tested against the in vitro brine shrimp toxicity assay at a dose of
1000 μg/ml. From the in vivo zebrafish embryo toxicity assay, results have shown that
compound 16 was having a non-toxic property based on the parameters such as
hatching rate, survival rate, heartbeat rate and obtained a LC50 value of 197.2 μg/mL.
Furthermore, the molecular docking analysis showed their binding interactions
between mushroom tyrosinase protein structure (PDB ID: 2Y9X) for compound 16
with a binding affinity of (-7.7 kcal/mol) and the compounds as the ligands through in
silico approach. These data suggest that potent halogenated xanthone derivatives have
the potential to be developed as new candidates for skin whitening agents with
antioxidant and non-toxic properties in cosmetic industries and for pigmentationrelated
diseases. |
|---|