Advanced Journal of Chemistry, Section B: Natural Products and Medical Chemistry
Volume:2 Issue: 4, Autumn 2020

Phytochemical investigation on the ethanol extract of Boswellia papyrifera stem barks let to the isolation of new sterol (29-methyl, nonanoate-cholest-7, 22-dien-3β-ol 2) along with three known related compounds, Stigmasterol 1, β-sitosterol-3-O-β-D-glucoside 3 and Spinasterol 3-O-β-Dglucopyranoside 4. Their structures were defined by various spectroscopic studies including 1D, 2D-NMR, MS analysis and by comparison with those reported in the literature.

A flexible polymer based on latex and CdTe Quantum Dots (QDs) is introduced here which shows color changing properties under UV light as the polymer is stretched. After synthesis of TGA-capped CdTe QDs with different sizes and emissions in the optimal conditions, the flexible polymer is synthesized and different colors such as green, pale green, white, and pale red were observed under UV light. The effective parameters of fluorescent QDs such as size, extinction coefficients, and concentrations were calculated by absorption and emission spectra.

Schiff bases are compounds with the general structure R2C=NR’. They can be prepared by the condensation of the primary amines with carbonyl compounds. In this paper, we have synthesized Schiff base ligand (L) by reacting semicarbazide with 2-acetylthiophene in ethanol solvent and its metal complexes have also been synthesized by using Zr4+, Pb2+ and U6+ ions. Schiff bases of semicarbazide are often having promising biological activities like anti-inflammatory, antidepressant, antiglycation, antibacterial, etc. Schiff base ligand and metal complexes were characterized and have shown appropriate results when analyzed on UV-Vis., NMR, FT-IR and antibacterial activities. They were tested against gram- negative [E. Coli. (MTCC No: 452)] and gram- positive [Bacillus sp (MTCC No: 297)] bacterial strains by using Kirby-Bauer’s method. Schiff base complexes of Zirconium [Zr(L)4]Cl2] and lead [Pb(L)2]Cl2] were found to be more active against both bacterial strains having a zone of inhibition 11.14 ± 0.2 & 10.23 ± 0.5 mm and 12.02 ± 0.3 & 11.05 ± 0.3 mm on E. Coli. and on Bacillus species respectively.

The need to control and ultimately eradicate the scourge of metal corrosion has become necessary given the high incidence of deaths and loss of property resulting from it. The choice of π-conjugated organic systems has been justified in that they are easier to produce and their modes and rates of adsorption are very superb, a consequence of the π-electrons. In this work, a Schiff base of the reaction of aniline and salicyaldehyde was applied as corrosion inhibitor on mild steel via weight loss techniques (at different inhibitor concentrations and at different temperatures) from which the corrosion rate (Cr), degree of surface coverage (θ) and the percentage inhibition efficiency (%IE) were calculated. The molecule was modelled and optimized using Density functional theory (DFT) with B3LYP correlation and 6-31G* and 6-31+G* basis sets to obtain the electronic properties like the frontier molecular orbitals energies (EHOMO and ELUMO), energy band gap (Eg), dipole moment (μ) and the reactivity descriptors like chemical hardness (η), softness (δ), global electrophilicity index (ω) and fraction of electrons transferred (ΔN). The Cr increased with increase in temperature and decreased as the inhibitor concentration increases while the %IE followed a reverse pattern. From the R2 values, the molecule’s adsorption obeyed the Freundlich adsorption isotherm. ΔG values which turned negative confirmed that the reactions are exothermic and spontaneous. The results obtained are consistent with available experimental data.

Steroids are one of the essential classes of bioactive compounds and are involved in many biochemical processes which include their role as signaling compounds, the alteration of membrane fluidity and the regulation of a variety of metabolic processes. In order to identify novel compounds with valuable pharmacological action, the synthesis of improved steroids is gaining much attention in recent times. Among those analogs, heterosteroids particularly azasteroids are one of the most important classes which display a variety of biological activities, often free from undesirable side effects. The challenges in the synthesis of steroids, particularly azasteroids, and the potential of azasteroids as novel drugs has prompted numerous investigations in this field. The synthetic methods leading to steroidal derivatives (azasteroids) with one or more nitrogen atoms are very limited. There are reports on the major skeletal types of steroids and their associated range of biological activities. In addition, there are increasing studies in which known non-steroidal pharmacophore are attached to the steroid skeleton with the aim that the latter might provide lipid solubility, receptor selectivity or membrane-binding properties. All these are testaments on the importance and the ubiquitous nature of steroids. The urgency for the syntheses of a wide array of steroids for several intended biomedical applications are found in the chemical and biochemical literatures. Several efforts are underway to achieve this milestone. There have been developments in therapies for the treatment of breast cancer which target the estrogen receptor. In the domain of rational drug design, a three-dimensional model of the CYP19 aromatase incorporating both the haem and the steroid substrate has been proposed.

The effective and economic removal of heavy metals from industrial effluents is one of the important issues globally. In this study, hydroxyapatite (HAP) was synthesized using the wet chemical precipitation method and was characterized using Fourier transform infrared (FTIR) spectroscopy, UV-Visible spectrometry, scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. Different physico-chemical parameters of the HAP such as color, bulk density, and pH were determined. Removal efficiency of Cr(VI) was investigated by different parameters such as initial concentration, contact time, pH, adsorbent dosage and temperature. Results showed that the adsorption of Cr (VI) was favorable in acidic medium. Adsorption kinetics using pseudo-first order and pseudo-second order kinetic models were tested on the experimental data. The Kinetics of the adsorption followed a pseudo-second order kinetics model as we obtained a higher correlation coefficient value of R2 = 0.978. The equilibrium data were evaluated using two adsorption isotherms: Langmuir and Freundlich adsorption isotherms. The equilibrium data fitted well with Langmuir adsorption isotherm model, showing monolayer coverage of Cr(VI) ions over the surface of HAP and this fact is supported by the Langmuir isotherm plot and the correlation coefficient value of R2 = 0.9639.

Cordyceps Sinensis, known as winter worm and summer grass. This review summarized the overview of C. sinensis; chemical constituents and its biological studies. Further the bibliometric analysis performed which will help to broaden the knowledge and understanding of its research, topics, and growing trends. The search term “Cordyceps sinensis” was typed in google scholar and the appeared articles (total 1,134 articles) are selected, having citations more than 100 are 40 articles. Further evaluated according to the journal, year of publication, manuscript type, and first author. To make it more comprehensive the articles having more than 10 citations in the year 2017-18, at least 1 citation in 2019, and all articles of the year 2020 were also presented separately. The average number of citations among the top 40 manuscripts was 189, ranging from the highest 636 to lowest is 102 citations. The maximum number of articles in the top 40 were published in the Biological and Pharmaceutical Bulletin (n=5) and Life sciences (n=5), followed by the Phytomedicine (n=3). The highest cited paper is by Zhu JS, “the scientific rediscovery of an ancient Chinese herbal medicine: Cordyceps sinensis Part I”, published in 1998 with total citation 636. The most prevalent theme in the title is a polysaccharide (n=13) followed by antioxidant (n =4). Most of the research is performed by Chinese researchers. This bibliometric analysis identified the most influential articles in the field of C. sinensis research and discussed the overview on it.

The overall aim of the maintenance and repair process in industrial companies is to reduce costs and increase the benefits of operating and optimize life cycle costs, taking into account all safety considerations. Choosing a maintenance and repair strategy is one of the most complex and necessary processes that can affect the safety and cost of equipment. The main aim of this study is to select a risk-based maintenance and repair strategy to improve safety, maintenance and repair indexes. Risk assessment integrates product reliability with safety and environmental issues and can therefore be considered as a decision-making tool for repair planning. One of the most important strategies in the field of maintenance and repair planning and optimization of related activities is the system or process of maintenance and repair with Reliability Centered Maintenance (RCM). This system provides a framework for all the physical facilities and equipment of organizations to continuously fulfill their planned tasks in the specified operational context. Risk analysis-based repair planning can reduce the likelihood of system failure and the consequences of such failures and help management make the right decisions to make the right investment in maintenance and repair and thus lead to better use of existing assets and capital

The main purpose of this paper is to provide a risk management model in the current processes of procurement and supply of equipment of project-based organizations in order to improve procurement management and effective performance of the mission. Procurement and supply is an important process for life survives of an organization and project, and it is a vital guarantee for achieving the goals and, in the first place, their success. In the procurement process, it is responsible for identifying, analyzing and providing appropriate solutions for responding, controlling and monitoring risks in the economic and production cycles. The lack of uncertainty and increase in influential factors in the purchasing and procurement process as well as complexity of purchasing systems have made it difficult for managers to achieve their goals. Depending on the type of activity and level of sensitivity of their assets, each organization and project deals with a different level of risks and hazards for which the risk management process should be implemented while challenges affecting the process of supplying required items should be prevented.