4,6-Diacetylresorcinol in Heterocyclic Synthesis,Part I: Synthesis and Biological Evaluation of Some New Linearly and Angularly Substituted Pyrano[3,2-g] Chromenes via Vilsmeier–Haack Formylation of 4,6-Diacetylresorcinol,Its Schiff Bases,and Hydrazones

Application of Vilsmeier–Haack reaction on 4,6-diacetylresorcinol (1) led to the formation of 4,6-dioxo-4H,6H-pyrano[3,2-g]chromene-3,7-dicarboxaldehyde (2) in good yield. The dicarboxaldehyde 2 was condensed with some carbon and nitrogen nucleophiles. Some aliphatic and aromatic Schiff bases of 4,6-diacetylresorcinol (1) were subjected to Vilsmeier–Haack formylation reaction to afford 4,6-bis(alkyl/arylimino)-4H,6H-pyrano[3,2-g]chromene-3,7-dicarbaldehydes 10, 14, and 15. Also, treatment of some bis-hydrazones of 4,6-diacetylresorcinol 16–19 with Vilsmeier–Haack reagent afforded the corresponding 4,6-bis(4-formylpyrazol-3-yl)resorcinols 20 and 21, which underwent oxidation with iodine to yield the pyrano[3,2-g]chromeno[4,3-c:7,6-c]dipyrazole-4,8-diones 22 and 23, respectively. Most of the synthesized compounds revealed weak antimicrobial activities. It was noticed that the dicarboxaldehydes 2, 10, 14, and 15 exhibited moderate antibacterial activity against Gram-positive bacteria, yeast, and fungus.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Effect of alteration processes on the distribution of radionuclides in uraniferous sedimentary rocks and their environmental impact, southwestern Sinai, Egypt

The contents of natural radionuclides in various types of sedimentary rocks in Um Bogma Formation and base of El Hashash Formation were determined by gamma-ray spectrometry. Three types of lower Carboniferous sedimentary rocks were investigated; sandstone (El Hashash Formation), dolostone and argillaceous sediments (Um Bogma Formation). The alteration processes are dolomitization, dedolomitization, karstification and lateritization. The specific radioactivity of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K determined in different samples, indicate that ²³⁸U and its decay products contribute primarily to the high natural radioactivity of rocks. The maximum concentration of ²³⁸U reached up to 2129.36 ppm in argillaceous sediments. The average concentrations of determined radionuclides (²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K) are 8.34 ppm, 7.88 ppm, 4.68 ppm and 0.3%, respectively in sandstone. In dolostones the average concentrations are 418.69 ppm, 808.75 ppm, 3.14 ppm and 0.29%, respectively. For argillaceous sediments are 276.88 ppm, 419.49 ppm, 11.47 ppm and 0.93%, respectively. The ²³⁸U/²²⁶Ra ratio in sandstone ranges between 0.89 and 1.25, while in dolostones and argillaceous sediments are 0.27–2.63 and 0.27–1.83, respectively. These variations in the concentrations of radioelements and their ratios are due to the action of the alteration processes affected these different sedimentary rocks in different times. Environmentally, the Ra_eq in dolostones and argillaceous sediments exceeds the permitted limits, while in the sandstone samples; it is within the permissible levels.     

A New Xanthone Glycoside from Mangifera indica L.: Physicochemical Properties and In Vitro Anti-Skin Aging Activities

A new xanthone glycoside, 1,3,5,6-tetrahydroxyxanthone-C-4-β-d-glucopyranoside was isolated from the methanol extract of Mangifera indica leaves (Anacardiaceae) growing in Egypt. The structure was clarified by 1D and 2D-NMR spectroscopic data. The physicochemical properties of the compound such as lipophilicity, solubility, and formulation considerations were predicted via in silico ADMET technique using the SwissADME server. This technique provided Lipinski’s rule of five, such as GIT absorption, distribution, metabolism, and skin permeation. The in vitro inhibitory activities against aging-mediated enzymes such as collagenase, elastase, hyaluronidase, and tyrosinase were assessed. The compound exhibited remarkable anti-collagenase, anti-elastase, anti-hyaluronidase, and anti-tyrosinase effects with IC₅₀ values of 1.06, 419.10, 1.65, and 0.48 µg/mL, respectively, compared to the positive control. The compound showed promising predicted aqueous solubility and reasonable skin penetration suggesting the suitability of the compound for topical formulation as an anti-aging agent for cosmetic preparations.     

Supersaturation-Based Drug Delivery Systems: Strategy for Bioavailability Enhancement of Poorly Water-Soluble Drugs

At present, the majority of APIs synthesized today remain challenging tasks for formulation development. Many technologies are being utilized or explored for enhancing solubility, such as chemical modification, novel drug delivery systems (microemulsions, nanoparticles, liposomes, etc.), salt formation, and many more. One promising avenue attaining attention presently is supersaturated drug delivery systems. When exposed to gastrointestinal fluids, drug concentration exceeds equilibrium solubility and a supersaturation state is maintained long enough to be absorbed, enhancing bioavailability. In this review, the latest developments in supersaturated drug delivery systems are addressed in depth.     

Ecofriendly chromatographic estimation of spasmolytic pharmaceutical mixture along with official toxic impurity, 3,5-dichloroaniline: Complete green profile appraisal

Nowadays, Green Analytical Chemistry is widely applied to provide various analytical methods with eco-friendly procedures employing the least toxic, harmful reagents on humans and the environment without affecting the efficacy of the determination. Accordingly, two eco-friendly, accurate, and reliable high-performance thin-layer chromatography-densitometry and high-performance liquid chromatographic methods were established for the determination and separation of two antispasmodic drugs, namely phloroglucinol and trimethylphloroglucinol in their pure, combined dosage form along with phloroglucinol toxic impurity, 3,5-dichloroaniline. For high-performance thin-layer chromatography-densitometry, efficient separation was developed via utilizing the stationary phase of high-performance thin-layer chromatography silica gel 60 F₂₅₄ plates and developing a system comprising of ethyl acetate-butanol-ammonia in the ratio of 8.0:2.0:0.2, by volume and scanning of the developed bands at 210.0 nm. The subsequent method is isocratic high-performance liquid chromatography with diode array detection in which separation was successively attained using XTerra RP-C₁₈ (250 × 4.6 mm, 5 μm) column as stationary phase and methanol-10.0 mM phosphate buffer, pH 3.7 ± 0.1 as mobile phase in the ratio of 75.0:25.0, v/v at flow rate 1.0 ml/min and scanning at 220.0 nm. The developed liquid chromatography methods were validated according to the International Council for Harmonization guidelines, and all results acknowledged their efficacy. Additionally, the proposed methods worked well for assessing the cited drugs in binary combined commercially available pharmaceutical formulation. The greenness profile of the present methods was assessed and estimated using various assessment tools, namely; Green Analytical Procedure Index, analytical eco-scale method, National Environmental Method Index in addition to Analytical GREEnness tool to evaluate the greenness of the provided methods with a statistical comparison between them to assess the more green ones.     

Facile synthesis of zirconia supported nanomaterials for efficient photocatalytic applications

The recent study enlightens the synthesis and characterization of zirconia (ZrO₂), Fe-doped ZrO₂ (Fe@ZrO₂), and Ni-doped ZrO₂ (Ni@ZrO₂) catalysts having new-fangled morphology with tuned band gap as photocatalysts for degradation of textile wastewater dyes methylene blue (MB), malachite green (MG), and their mixtures. SEM imaging of Fe@ZrO₂ and Ni@ZrO₂ is interestingly varied from ZrO₂ as well as doping of transition metals greatly affects the morphology of composites. The optimization study depicts that the pH, time (min) and catalyst amount (g) have a direct relation with degradation efficiency, while the dye concentration (mg/L) has an indirect relation as well. The photocatalytic studies depict that the degradation of MB and MG follows oxidation pathway via hydroxyl radicals (OH^•) and holes. Reusability of catalysts corresponds to a little decrease in degradation efficiency in the first two cycles and decreases to about ∼10% (Ni@ZrO₂) and ∼12% (Fe@ZrO₂) in next three cycles.     

Simple and convenient routes to new polyheterocycles incorporating pyrazole,thiazole, thiophene,and 1,3,4‐thiadiazole moieties

The cyanothioacetanilide derivative 3 reacted readily with either α‐halocarbonyl compounds 4 or α‐halodicarbonyl compounds 8 to afford the same thiophene derivatives 6 . Compound 3 also reacted with hydrazonoyl chlorides 12 and 16 and furnished the new polyheterocyles 14 and 17 , respectively. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:248–251, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10024