scholarly journals Alternative Approach for Specific Tyrosinase Inhibitor Screening: Uncompetitive Inhibition of Tyrosinase by Moringa oleifera

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4576
Author(s):  
Farah J. Hashim ◽  
Sukanda Vichitphan ◽  
Jaehong Han ◽  
Kanit Vichitphan
Keyword(s):  
Moringa Oleifera ◽  
Vital Role ◽  
Inhibition Kinetics ◽  
Uncompetitive Inhibition ◽  
Phytochemical Investigation ◽  
Alternative Approach ◽  
Ic50 Values ◽  
Copper Oxidase ◽  
Kinetics Of ◽  
Inhibition Pattern

Tyrosinase (TYR) is a type III copper oxidase present in fungi, plants and animals. The inhibitor of human TYR plays a vital role in pharmaceutical and cosmetic fields by preventing synthesis of melanin in the skin. To search for an effective TYR inhibitor from various plant extracts, a kinetic study of TYR inhibition was performed with mushroom TYR. Among Panax ginseng, Alpinia galanga, Vitis vinifera and Moringa oleifera, the extracts of V. vinifera seed, A. galanga rhizome and M. oleifera leaf reversibly inhibited TYR diphenolase activity with IC50 values of 94.8 ± 0.2 µg/mL, 105.4 ± 0.2 µg/mL and 121.3 ± 0.4 µg/mL, respectively. Under the same conditions, the IC50 values of the representative TYR inhibitors of ascorbic acid and kojic acid were found at 235.7 ± 1.0 and 192.3 ± 0.4 µg/mL, respectively. An inhibition kinetics study demonstrated mixed-type inhibition of TYR diphenolase by A. galanga and V. vinifera, whereas a rare uncompetitive inhibition pattern was found from M. oleifera with an inhibition constant of Kii 73 µg/mL. Phytochemical investigation by HPLC-MS proposed luteolin as a specific TYR diphenolase ES complex inhibitor, which was confirmed by the inhibition kinetics of luteolin. The results clearly showed that studying TYR inhibition kinetics with plant extract mixtures can be utilized for the screening of specific TYR inhibitors.

Purification of Polyphenol Oxidase from Potato and Investigation of the Inhibitory Effects of Phenolic Acids on Enzyme Activity

2020 ◽  
Vol 27 (3) ◽  
pp. 187-192 ◽  
Author(s):  
Songül Bayrak ◽  
Cansu Öztürk ◽  
Yeliz Demir ◽  
Zuhal Alım ◽  
Ömer İrfan Küfrevioglu
Keyword(s):  
Polyphenol Oxidase ◽  
Phenolic Acids ◽  
Competitive Inhibition ◽  
Specific Activity ◽  
Inhibition Kinetics ◽  
Inhibitory Effects ◽  
Inhibition Effect ◽  
Ic50 Values ◽  
Sepharose 4B ◽  
Kinetics Of

Background: Polyphenol Oxidase (PPO) belongs to the oxidoreductase enzyme family. Methods: Here, PPO was purified from potato using Sepharose 4B-L-tyrosine-p-aminobenzoic acid affinity chromatography. It determined the interactions between some phenolic acids and the enzyme. Results: The enzyme was obtained with a specific activity of 15333.33 EU/mg protein and 7.87- fold purification. It was found that phenolic acids exhibited inhibitory properties for PPO. The IC50 values of the phenolic acids were found in the range of 0.36-2.12 mM, and their Ki values were found in the range of 0.28± 0.07-1.72±0.32 mM. It was determined that all studied compounds displayed a competitive inhibition effect. Among these compounds, 3-hydroxybenzoic acid was found to be the most effective PPO inhibitor (Ki: 0.28±0.07 mM). Conclusion: Investigating the inhibition kinetics of the enzyme will simplify the testing of PPO inhibitor candidates.

Phytochemical Constituents of Annona reticulata and their Cytotoxic Activity

2020 ◽  
Vol 17 (3) ◽  
pp. 206-210
Author(s):  
Ty Viet Pham ◽  
Thang Quoc Le ◽  
Anh Tuan Le ◽  
Hung Quoc Vo ◽  
Duc Viet Ho
Keyword(s):  
Cytotoxic Activity ◽  
Cell Lines ◽  
Structural Determination ◽  
Phytochemical Investigation ◽  
Ic50 Values ◽  
Phytochemical Constituents ◽  
First Time ◽  
Annona Reticulata

A phytochemical investigation of the leaves of Annona reticulata led to the isolation and structural determination of β-sitosterol (1), ent-pimara-8(14),15-dien-19-oic acid (2), ent-pimara- 8(14),15-dien-19-ol (3), quercetin (4), quercetin 3-O-α-L-arabinopyranoside (5), and a mixture of quercetin 3-O-β-D-galactopyranoside (6a) and quercetin 3-O-β-D-glucopyranoside (6b). Of these, compounds 2 and 3 were isolated from the genus Annona for the first time. Compound 3 showed strong cytotoxicity against SK-LU-1 and SW626 cell lines with IC50 values of 17.64 ± 1.07 and 19.79 ± 1.41 μg mL-1, respectively.

Molecular docking studies of tea (Thea sinensis Linn.) polyphenols inhibition pattern with Rat P-glycoprotein

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Babar Ali ◽  
Qazi Mohammad Sajid Jamal ◽  
Showkat R. Mir ◽  
Saiba Shams ◽  
Mohammad Amjad Kamal
Keyword(s):  
Amino Acids ◽  
Molecular Docking ◽  
Binding Energy ◽  
Oral Administration ◽  
Docking Studies ◽  
Vital Role ◽  
Glycoprotein P ◽  
High Affinity ◽  
P Glycoprotein ◽  
Inhibition Pattern

AbstractSince 3000 B.C., evergreen plant Thea sinensis (Theaceae) is used both as a social and medicinal beverage. Leaves of T. sinensis contain amino acids, vitamins, caffeine, polysaccharides and polyphenols. Most of the natural medicinal actions of tea are due to the availability and abundance of polyphenols mainly catechins. It has also been stated that some catechins were absorbed more rapidly than other compounds after the oral administration of tea and could increase the bio-enhancing activities of anticancer drugs by inhibiting P-glycoprotein (P-gp). The results of the molecular docking showed that polyphenols bind easily to the active P-gp site. All compounds exhibited fluctuating binding affinity ranged from −11.67 to −8.36 kcal/mol. Observed binding energy required for theaflavin to bind to P-gp was lowest (−11.67 kcal/mol). The obtained data that supports all the selected polyphenols inhibited P-gp and therefore may enhance the bioavailability of drugs. This study may play a vital role in finding hotspots in P-gp and eventually may be proved useful in designing compounds with high affinity and specificity to the protein.

scholarly journals Highly Oxygenated Triterpenoids and Diterpenoids from Fructus Rubi (Rubus Chingii Hu) and Their NF-kappa B Inhibitory Effects

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1911
Author(s):  
Jiang Wan ◽  
Xiao-Juan Wang ◽  
Nan Guo ◽  
Xi-Ying Wu ◽  
Juan Xiong ◽  
...  
Keyword(s):  
Inhibitory Effects ◽  
Nf Kappa B ◽  
Pentacyclic Triterpenoids ◽  
Chemical Structures ◽  
Phytochemical Investigation ◽  
Ic50 Values ◽  
Rubus Chingii ◽  
Rubus Chingii Hu ◽  
Type 3

During a phytochemical investigation of the unripe fruits of Rubus chingii Hu (i.e., Fructus Rubi, a traditional Chinese medicine named “Fu-Pen-Zi”), a number of highly oxygenated terpenoids were isolated and characterized. These included nine ursane-type (1, 2, and 4–10), five oleanane-type (3, 11–14), and six cucurbitane-type (15–20) triterpenoids, together with five ent-kaurane-type diterpenoids (21–25). Among them, (4R,5R,8R,9R,10R,14S,17S,18S,19R,20R)-2,19α,23-trihydroxy-3-oxo-urs-1,12-dien-28-oic acid (rubusacid A, 1), (2R*,4S*,5R*,8R*,9R*,10R*,14S*,17S*, 18S*,19R*,20R*)-2α,19α,24-trihydroxy-3-oxo-urs-12-en-28-oic acid (rubusacid B, 2), (5R,8R,9R,10R, 14S,17R,18S,19S)-2,19α-dihydroxy-olean-1,12-dien-28-oic acid (rubusacid C, 3), and (3S,5S,8S,9R, 10S,13R,16R)-3α,16α,17-trihydroxy-ent-kaur-2-one (rubusone, 21) were previously undescribed. Their chemical structures and absolute configurations were elucidated on the basis of spectroscopic data and electronic circular dichroism (ECD) analyses. Compounds 1 and 3 are rare naturally occurring pentacyclic triterpenoids featuring a special α,β-unsaturated keto-enol (diosphenol) unit in ring A. Cucurbitacin B (15), cucurbitacin D (16), and 3α,16α,20(R),25-tetrahydroxy-cucurbita-5,23- dien-2,11,22-trione (17) were found to have remarkable inhibitory effects against NF-κB, with IC50 values of 0.08, 0.61, and 1.60 μM, respectively.

scholarly journals Mammalian Arginase Inhibitory Activity of Methanolic Extracts and Isolated Compounds from Cyperus Species

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1694
Author(s):  
Kamel Arraki ◽  
Perle Totoson ◽  
Alain Decendit ◽  
Andy Zedet ◽  
Justine Maroilley ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Methanolic Extract ◽  
Significant Inhibition ◽  
Isolation And Identification ◽  
Vasorelaxant Effect ◽  
Methanolic Extracts ◽  
Phytochemical Investigation ◽  
Ic50 Values ◽  
First Time

Polyphenolic enriched extracts from two species of Cyperus, Cyperus glomeratus and Cyperus thunbergii, possess mammalian arginase inhibitory capacities, with the percentage inhibition ranging from 80% to 95% at 100 µg/mL and 40% to 64% at 10 µg/mL. Phytochemical investigation of these species led to the isolation and identification of two new natural stilbene oligomers named thunbergin A-B (1–2), together with three other stilbenes, trans-resveratrol (3), trans-scirpusin A (4), trans-cyperusphenol A (6), and two flavonoids, aureusidin (5) and luteolin (7), which were isolated for the first time from C.thunbergii and C. glomeratus. Structures were established on the basis of the spectroscopic data from MS and NMR experiments. The arginase inhibitory activity of compounds 1–7 was evaluated through an in vitro arginase inhibitory assay using purified liver bovine arginase. As a result, five compounds (1, 4–7) showed significant inhibition of arginase, with IC50 values between 17.6 and 60.6 µM, in the range of those of the natural arginase inhibitor piceatannol (12.6 µM). In addition, methanolic extract from Cyperus thunbergii exhibited an endothelium and NO-dependent vasorelaxant effect on thoracic aortic rings from rats and improved endothelial dysfunction in an adjuvant-induced arthritis rat model.

An Alternative Approach to Analyzing the Interstitial Decay from the End of Range Damage During Millisecond Annealing

2008 ◽  
Vol 1070 ◽  
Author(s):  
Renata Camillo-Castillo ◽  
Mark E Law ◽  
Kevin S Jones
Keyword(s):  
Annealing Time ◽  
Dwell Time ◽  
Extended Defects ◽  
Temperature Dependent ◽  
Temperature Regimes ◽  
Alternative Approach ◽  
Small Times ◽  
Conventional Annealing ◽  
Kinetics Of ◽  
Anneal Temperature

ABSTRACTFlash-assist Rapid Thermal Processing (RTP) presents an opportunity to investigate annealing time and temperature regimes which were previously not accessible with conventional annealing techniques such as Rapid Thermal Annealing. This provides a unique opportunity to explore the early stages of the End of Range (EOR) damage evolution and also to examine how the damage evolves during the high temperature portion of the temperature profile. However, the nature of the Flash-assist RTP makes it is extremely difficult to reasonably compare it to alternative annealing techniques, largely because the annealing time at a given temperature is dictated by the FWHM of the radiation pulse. The FWHM for current flash tools vary between 0.85 and 1.38 milliseconds, which is three orders of magnitude smaller to that required for a RTA to achieve similar temperatures. Traditionally, the kinetics of the extended defects has been studied by time dependent studies utilizing isothermal anneals; in which specific defect structures could be isolated. The characteristics of Flash-assist RTP do not allow for such investigations in which the EOR defect evolution could be closely tracked with time. Since the annealing time at the target temperature for the Flash-assist RTP is essentially fixed to very small times on the order of milliseconds, isochronal anneals are a logical experimental approach to temperature dependent studies. This fact presents a challenge in the data analysis and comparison. Another feature of Flash-assist RTP which makes the analysis complex is the ramp time relative to the dwell time spent at the peak fRTP temperature. As the flash anneal temperature is increased the total ramp time can exceed the dwell time at the peak temperature, which may play a significantly larger role in dictating the final material properties. The inherent characteristics of Flash-assist RTP have consequently required the development of another approach to analyzing the attainable experimental data, such that a meaningful comparison could be made to past studies. The adopted analysis entails the selection of a reference anneal, from which the decay in the trapped interstitial density can be tracked with the flash anneal temperature, allowing for the kinetics of the interstitial decay to be extracted.

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