Bilal Ahmad Khan

Phytochemistry of Daphne oleoides.

Abstract Genus Daphne belongs to the Thymelaeaceae family and consists of 70 species. Its various species exist in Europe, Philippine Islands, temperate and subtropical Asia, North Africa, Australia and Pacific. In Pakistan, Daphne is represented by three species. Our focused Daphne oleoides is widely found in diverse climatic conditions from northern cold to central hot regions which creates a rich diversity and novelty in biosynthetic levels of its chemical constituents and hence is a great opportunity. Daphne oeloides is a proven rich source of a variety of unique and interesting nature-made skeletons with a wide range of therapeutic properties. D. oleoides possesses effective therapeutic properties, therefore, has been used in herbal medicines and is still being used to treat various diseases. The modern research by various groups, including ourselves, has resulted in the isolation of a number of natural molecules including some novel tris- and bis- coumarins, daphnane diterpenoids and lignoids. Therefore, due to novelty and richness of the nature-made molecules, and their therapeutic potential combined with our significant work on D. oleoides, this report covers chemical constituents isolated from D. oleoides. The pharmacological activities of the isolated compounds and use of this species in folk medicine have also been reviewed.

Synthesis, structure–activity relationship and molecular docking of 3-oxoaurones and 3-thioaurones as acetylcholinesterase and butyrylcholinesterase inhibitors

The present study describes efficient and facile syntheses of varyingly substituted 3-thioaurones from the corresponding 3-oxoaurones using Lawessons reagent and phosphorous pentasulfide. In comparison, the latter methodology was proved more convenient, giving higher yields and required short and simple methodology. The structures of synthetic compounds were unambiguously elucidated by IR, MS and NMR spectroscopy. All synthetic compounds were screened for their inhibitory potential against in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. Molecular docking studies were also performed in order to examine their binding interactions with AChE and BChE human proteins. Both studies revealed that some of these compounds were found to be good inhibitors against AChE and BChE.

Synthesis, structure-activity relationship and molecular docking studies of 3- O -flavonol glycosides as cholinesterase inhibitors

The prime objective of this research work is to prepare readily soluble synthetic analogues of naturally occurring 3-O-flavonol glycosides and then investigate the influence of various substituents on biological properties of synthetic compounds. In this context, a series of varyingly substituted 3-O-flavonol glycosides have been designed, synthesized and characterized efficiently. The structures of synthetic molecules were unambiguously corroborated by IR, 1H, 13C NMR and ESI-MS spectroscopic techniques. The structure of compound 22 was also analyzed by X-ray diffraction analysis. All the synthetic compounds (21-30) were evaluated for in vitro inhibitory potential against cholinesterase enzymes. The results displayed that most of the derivatives were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with varying degree of IC50 values. The experimental results were further encouraged by molecular docking studies in order to explore their binding behavior with the active pocket of AChE and BChE enzymes. The experimental and theoretical results are in parallel with one another.

Biotechnology: A powerful tool for the removal of cadmium from aquatic systems

The prime objective of the present research work was to evaluate the efficiency of bio-machine for the removal of Cadmium (Cd) from aquatic systems. Aspergillus niger fungus was used as bio-machine to remove Cd from aquatic systems. Twenty three different strains (IIB-1 to IIB-23) were isolated from industrial effluents and the Langmuir and Freundlich models were applied to the best Cadmium removal strain IIB-23 in order to obtain the adsorption parameters. Different parameters such as pH, temperatur e, contact time, initial metal concentratio, and biomass dosage on the biosorption of Cd were studied. The percent removal of Cd initially increased with an increase in pH ranging from 5.5-6.5 and then decreased by increasing pH from 7.0-7.5. An optimized pH used for Cd removal from aquatic systems was found to be 6.5. Additionally, an optimum amount of biomass was 1.33 g for the maximum removal of Cd from the aqueous solutions with initial metal concentration of 75 mg/L. The results obtained thus indicated that Langmuir model is the best suited for the removal of Cd from aquatic systems.

Low-temperature solution-phase route to sub-10 nm titanium oxide nanocrystals having super-enhanced photoreactivity

High-purity anatase nanocrystals were prepared by using a low-temperature surfactant-assisted solution-phase method. Titanium tetra-isopropoxide (TTIP) was used as a precursor, polyethylene glycol (PEG) as a surfactant, and isopropyl alcohol (IPA) and water as solvent. An isopropanolic solution of TTIP and PEG was mixed with an aqueous acidic solution at about 60 °C to yield a whitish sol that, after being baked at 60 °C for 6 hours, was transformed into phase-pure anatase crystals with dimensions of about 8 nm. By varying the mass of the PEG surfactant from 0.5 to 2 g, the particle dimensions could be controlled to be between 8 and 11 nm. Thermogravimetric analysis in combination with transmission electron microscopy (TEM), XRD, and Raman, Ultraviolet-visible (UV-vis) and infrared spectroscopies showed the nanocrystals with dimensions of 8–11 nm to be composed of an anatase lattice with hydroxyl bound to the surface. These nanocrystals showed much improved efficiency for photodegradation of methylene blue as compared with the commercial Degussa P25, due to the extraordinarily increased surface area. These findings may inspire the engineering of highly active subnanometer-sized nanocrystals for energy- and environment-related applications.

Corrigendum to “Synthesis, structure-activity relationship and molecular docking studies of 3- O -flavonol glycosides as cholinesterase inhibitors” [Bioorg. Med. Chem. 26 (12) (2018) 3696–3706]

a Department of Chemistry, University of Gujrat, Gujrat 50700, Pakistan Department of Chemistry, Govt. College Women University, Sialkot 51300, Pakistan c Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan d Department of Chemistry, University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan e Department of Physics, University of Sargodha, Sargodha, Pakistan H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan g Department of Clinical Pharmacy, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, P.O. Box 31441, Dammam, Saudi Arabia