Adamantyl pyran-4-one derivatives and their in vitro antiproliferative activity

Oxidovanadium(IV) Porphyrin-Imidazole Complex-Catalyzed One-Pot, Three-Component Green Synthesis of Biologically Active Pyrano[2,3-d]pyrimidine and 4H-Chromene Heterocycles

A β-functionalized porphyrin ligand {H2TPP(Phen)}, has been synthesized and subsequently employed as a dibasic tetradentate ligand in synthesizing its vanadyl complex 2-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)-5,10,15,20-tetraphenylporphyrinatooxido-vanadium(IV)[VIVOTPP(Phen)] (1). Comprehensive characterization of the ligand {H2TPP(Phen)} and its vanadyl(IV) complex (1) was achieved through various analytical and spectroscopic techniques, including NMR, ultraviolet-visible (UV-vis), EPR, and MALDI-TOF mass spectrometry and elemental analysis. Electrochemical studies indicated that the free base porphyrin {H2TPP(Phen)} tends to four successive reduction peaks and two oxidation peaks observed in cyclic voltammetry. In contrast, the metalated complex [VIVOTPP(Phen)] displayed two successive reversible reductions and two oxidation peaks. The synthesized vanadyl(IV)-porphyrin complex (1) was further employed as an efficient and reusable catalyst in an environmentally friendly, one-pot, three-component synthesis of biologically and clinically relevant pyrano[2,3-d]pyrimidine (Ca-Ch, Da-Dg) and 4H-chromene (Ga-Gj, Ha-Hj) heterocycles. Based on the current literature regarding one-pot, multicomponent reactions, two distinct and plausible mechanistic pathways are postulated for these transformations. A detailed mechanistic investigation, including the isolation of intermediates and stepwise reaction analysis, revealed that the type of 1,3-dicarbonyl compound used is pivotal in determining the operative mechanistic pathway in these reactions. The current catalytic protocol developed for the synthesis of pyrano[2,3-d]pyrimidine and 4H-chromene heterocycles presents several advantages over existing methodologies, including the use of an eco-friendly solvent (ethanol), high product yields (up to 97%), shorter reaction time scale (30 min), high turnover frequency (TOF) values (up to 14.7 min-1), and excellent catalyst reusability over five catalytic cycles.

Fungal production of kojic acid and its industrial applications

Kojic acid has gained its importance after it was known worldwide that the substance functions primarily as skin-lightening agent. Kojic acid plays a vital role in skin care products, as it enhances the ability to prevent exposure to UV radiation. It inhibits the tyrosinase formation which suppresses hyperpigmentation in human skin. Besides cosmetics, kojic acid is also greatly used in food, agriculture, and pharmaceuticals industries. Conversely, according to Global Industry Analysts, the Middle East, Asia, and in Africa especially, the demand of whitening cream is very high, and probably the market will reach to $31.2 billion by 2024 from $17.9 billion of 2017. The important kojic acid-producing strains were mainly belongs to the genus Aspergillus and Penicillium. Due to its commercial potential, it continues to attract the attention for its green synthesis, and the studies are still widely conducted to improve kojic acid production. Thus, the present review is focused on the current production processes, gene regulation, and limitation of its commercial production, probable reasons, and possible solutions. For the first time, detailed information on the metabolic pathway and the genes involved in kojic acid production, along with illustrations of genes, are highlighted in the present review. Demand and market applications of kojic acid and its regulatory approvals for its safer use are also discussed. KEY POINTS: • Kojic acid is an organic acid that is primarily produced by Aspergillus species. • It is mainly used in the field of health care and cosmetic industries. • Kojic acid and its derivatives seem to be safe molecules for human use.

Novel N,N'-Disubstituted Selenoureas as Potential Antioxidant and Cytotoxic Agents

A series of 30 novel N,N disubstituted selenoureas were synthesized, characterized, and their antioxidant ability was tested using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) assays. Additionally, their cytotoxic activity was tested in vitro in a panel of three different cancer (breast, lung and colon) and two normal cell lines. Each selenourea entity contains a para-substituted phenyl ring with different electron-withdrawing and electron-donating groups, and different aliphatic and aromatic nuclei. All of the synthesized selenoureas present antioxidant capacity at high concentrations in the DPPH assay, and three of them (2b, 2c and 2d) showed greater radical scavenging capacity than ascorbic acid at lower concentrations. These results were confirmed by the ABTS assay, where these novel selenoureas present even higher antioxidant capacity than the reference compound Trolox. On the other hand, 10 selenoureas present IC₅₀ values below 10 µM in at least one cancer cell line, resulting in the adamantyl nucleus (6a–6e), the most interesting in terms of activity and selectivity. Outstanding results were found for selenourea 6c, tested in the NCI60 cell line panel and showing an average GI₅₀ of 1.49 µM for the 60 cell lines, and LC₅₀ values ranging from 9.33 µM to 4.27 µM against 10 of these cancer cell lines. To gain insight into its anticancer activity mechanism, we investigated the cell cycle progression of the promising compound 6c, as well as the type of programmed-cell death in a colon cancer cell line it provokes (HT-29). Compound 6c provoked S phase cell cycle arrest and the induction of cell death was independent of caspase activation, suggesting autophagy, though this assertion requires additional studies. Overall, we envision that this compound can be further developed for the potential treatment of colon cancer.

Synthesis, in vitro cytotoxic and apoptotic effects, and molecular docking study of novel adamantane derivatives

[4-(Adamantane-1-carboxamido)-3-oxo-1-thia-4-azaspiro[4.4]nonan-2-yl]acetic acid (4a) and [4-(adamantane-1-carboxamido)-8-nonsubstituted/substituted-3-oxo-1-thia-4-azas-piro[4.5]decane-2-yl]acetic acid (4b-g) derivatives were synthesized; their structures were verified by elemental analysis, infrared spectroscopy, ¹ H nuclear magnetic resonance (NMR), ¹³ C NMR, and mass spectroscopy data; and their in vitro cytotoxicity activities were investigated against human hepatocellular carcinoma, human prostate adenocarcinoma, and human lung carcinoma cell lines (HepG2, PC-3, and A549, respectively), and a mouse fibroblast cell line (NIH/3T3). All compounds, except compound 4e, were found as cytotoxic, especially on A549 cells as compared with the other cells (selectivity index = 2.01-11.6). As a further step, the effects of compounds 4a-c on apoptosis induction were tested and the expression of selected apoptosis genes was analyzed. Among the selected compounds, compound 4a induced apoptosis remarkably. Moreover, computational calculations of the binding of compounds 4a-c to the BIR3 domain of the human inhibitor of apoptosis protein revealed ligand-protein interactions at the atomistic level and emphasized the importance of a hydrophobic moiety on the ligands for better binding.

Chemo-enzymatic three-step conversion of glucose to kojic acid

Kojic acid is an important biomolecule, currently produced by fermentation and having a wide range of potential applications. A faster and more direct chemical route could open the door for its large-scale production and wider utilization in biorefineries. Here we describe an efficient method for the preparation of kojic acid from d-glucose via glucosone by a three-step chemo-enzymatic route.