Molecular Docking, Synthesis, and Tyrosinase Inhibition Activity of Acetophenone Amide: Potential Inhibitor of Melanogenesis.

Tyrosinase and its related proteins are responsible for pigmentation disorders, and inhibiting tyrosinase is an established strategy to treat hyperpigmentation. The carbonyl scaffolds can be effective inhibitors of tyrosinase activity, and the fact that both benzoic and cinnamic acids are safe natural substances with such a scaffolded structure, it was speculated that hydroxyl-substituted benzoic and cinnamic acid derivatives may exhibit potent tyrosinase inhibitory activity. These moieties were incorporated into new chemotypes that displayed in vitro inhibitory effect against mushroom tyrosinase with a view to explore antimelanogenic ingredients. The most active compound, 2-((3-acetylphenyl)amino)-2-oxoethyl(E)-3-(2,4-dihydroxyphenyl)acrylate (5c), inhibited mushroom tyrosinase with an IC50 of 0.0020 ± 0.0002 µM, while 2-((3-acetylphenyl)amino)-2-oxoethyl 2,4-dihydroxybenzoate (3c) had an IC50 of 27.35 ± 3.6 µM in comparison to the positive control arbutin and kojic acid with a tyrosinase inhibitory activity of IC50 of 191.17 ± 5.5 µM and IC50 of 16.69 ± 2.8 µM, respectively. Analysis of enzyme kinetics revealed that 5c is a competitive and reversible inhibitor with dissociation constant (Ki) value 0.0072 µM. In silico docking studies with mushroom tyrosinase (PDB ID 2Y9X) predicted possible binding modes in the enzymatic pocket for these compounds. The orthohydroxyl of the cinnamic acid moiety of 5c is predicted to form hydrogen bond with the active site side chain carbonyl of Asn 260 (2.16 Å) closer to the catalytic site Cu ions. The acetyl carbonyl is picking up another hydrogen bond with Asn 81 (1.90 Å). The inhibitor 5c passed the panassay interference (PAINS) alerts. This study presents the potential of hydroxyl-substituted benzoic and cinnamic acids and could be beneficial for various cosmetic formulations.

Investigation of Plantago ovata Husk as Pharmaceutical Excipient for Solid Dosage Form (Orodispersible Tablets).

The objective of the study was to investigate the suitability of the Plantago ovata (PO) husk as a pharmaceutical excipient. Various phytoconstituents of the husk were determined according to the standard test procedures. The Plantago ovata husk was evaluated for various pharmaceutical parameters related to flow, swelling index, and compressibility index. Orodispersible tablets (ODTs) were prepared, containing different concentrations (2.5, 3, 5, 7.5, 10, and 15% w/w) of the Plantago ovata husk. Before compression, all the formulations were evaluated for their flow. Compressed ODTs were evaluated for physical characteristics (physical appearance, weight and weight variation, thickness, and moisture content), mechanical strength (crushing strength, specific crushing strength, tensile strength, and friability), disintegration behavior (disintegration time and oral disintegration time), drug content, and in vitro drug release. Phytochemical evaluation of the Plantago ovata husk confirmed the presence of various phytoconstituents like alkaloids, tannins, glycosides, saponins, flavonoids, and phenols. SEM photograph of the Plantago ovata husk showed that it has a fibrous structure, with a porous and rough surface. The Plantago ovata husk had a high swelling index (380%) which decreased by pulverization (310%). Precompression evaluation of the powder blend for all the formulations of ODTs showed good flow properties, indicating that the Plantago ovata husk improved the rheological characteristics of the powder blend. Compressed ODTs had good mechanical strength, and their friability was within the official limits (<1%). Best disintegration was observed with formulation F-6 containing 10% w/w of the Plantago ovata husk. It is concluded that the Plantago ovata husk can be used as a disintegrant in the formulation of ODTs.

Antihyaluronidase and Alkaline Phosphatase (ALP) Activities of Medicinal Plants to Combat Echis carinatus Venom-Induced Toxicities.

Snakebite is one of the most neglected diseases of developing countries. Deaths due to snakebite envenoming are quite high in Pakistan, and many deaths are caused by Echis carinatus envenomation. Traditional use of medicinal plants against snakebites is a common practice in Pakistan due to countless benefits. The current study was performed with the objective to evaluate eighteen Pakistani medicinal plants inhibitory potential against hyaluronidase and alkaline phosphatase enzymes of Pakistani Echis carinatus venom. Hyaluronidase activity (0.2-1.6 mg/0.1 mL) and alkaline phosphatase activity (0.1-0.8 mg/0.1 mL) were measured in dose-dependent manner. Crude methanolic extracts of medicinal plants were used for in vitro investigation of their inhibitory activity against toxic enzymes. All active plants were fractioned using different solvents and were again analyzed for inhibitory activity of same enzymes. Results indicated all plants were able to neutralize hyaluronidase that Swertia chirayita (Roxb. ex Flem.) Karst., Terminalia arjuna Wight and Arn, Rubia cordifolia Thumb., and Matthiola incana (L.) R.Br. inhibited maximum hyaluronidase activity equivalent to standard reference (p > 0.5). Pakistani medicinal plants are dense with natural neutralizing metabolites and other active phytochemicals which could inhibit hyaluronidase activity of Pakistani Echis carinatus venom. Further advanced studies at molecular level could lead us to an alternative for envenoming of Pakistani Echis carinatus venom.

Enzyme Inhibitory Kinetics and Molecular Docking Studies of Halo-Substituted Mixed Ester/Amide-Based Derivatives as Jack Bean Urease Inhibitors.

A series of halo-substituted mixed ester/amide-based analogues 4a-l have been prepared as jack bean urease inhibitor, which showed good to excellent inhibition of enzyme activity. The role of halo-substituted benzoyl moieties and alkyl substituted anilines in urease inhibitory kinetics was also investigated. The alkyl-substituted anilines 1a-b reacted with chloroacetyl chloride to afford intermediates 2a-b, which were then reacted with different halo-substituted benzoic acids 3a-f to prepare the title compounds 4a-l. The chemical structures of final products 4a-l were ascertained by FTIR, 1H NMR, 13C NMR, and mass spectra. The compound 4b showed remarkable activity with IC501.6 ± 0.2 nM, better than the standard thiourea having IC50472.1 ± 135.1 nM. The 2-chloro-substituted phenyl ring on one side of compound 4b and 4-isopropyl-substituted benzene on the other side play an essential role in inhibition of urease activity. Lineweaver-Burk plots (kinetics study) indicated about 4b derivative as a mixed type of inhibitor. The virtual screening performed against urease enzyme (PDBID 4H9M) showed that compounds 4b and 4e have binding energies of -7.8 and -7.9 Kcal/mol, respectively. Based upon our results, it was found that derivative 4b is a highly potent urease inhibitor, better than the standard thiourea.