Gideon Adamu Shallangwa

MNDO and DFT Computational Study on the Mechanism of the Oxidation of 1,2-Diphenylhydrazine by Iodine

The reaction mechanisms of the oxidation of 1,2-diphenylhydrazine by iodine have been examined using semiempirical and density functional theory methods, the oxidation proceeded via two independent pathways that can be separately monitored. One pathway involved the chain multistep mechanism. The other pathway occurred via a one-step mechanism in which a “cyclic” activated complex was formed which on disproportionation gave the products. The one-step “cyclic” activated complex mechanism proceeds more rapidly than the chain multistep mechanism. The results were explained by analyses based on computational energetics of the optimised reactants, intermediates, transition states, and products of the reaction of iodine with 1,2-diphenylhydrazine.

Effect of Acetylation on Stability to Retrogradation of Starch Extracted from Wild Polynesian Arrowroot (Tacca leontopetaloides (L.) Kuntze) for Utilization as Adhesive on Paper

Starch was isolated from T. leontopetaloides tubers, chemically modified by acetylation with varying amounts of acetic anhydride. Monolayer of the ten acetylated and control starch powders was exposed on roof top for five weeks and pastes of both exposed and unexposed (control) samples were prepared with distilled water (1 : 3 w/w). The effects of acetylation, degree of substitution (DS), and exposure to sunlight were investigated to evaluate the retrogradation tendency of the adhesive pastes from changes in syneresis, tack strength, optical clarity, viscosity, gelation time, and drying time. The results obtained showed that all the adhesive properties studied were affected by both DS and exposure to sunlight. While tack strength, viscosity, and drying time were found to increase with increase in DS, syneresis, optical clarity, and gelation time were found to decrease with increase in DS. Increase in tack strength and reduction in syneresis imply that the acetylation treatment has made T. leontopetaloides starch more suitable for use in remoistenable adhesive applications. The reduction in syneresis, optical clarity, and gelation time with increase in DS was attributed to the strengthening of the bonds between the amylose and amylopectin molecules, preventing water leaching out of the starch granules.

In silico modelling of quantitative structure–activity relationship of multi-target anticancer compounds on k-562 cell line

The pGI50 cytotoxicity values of 112 compounds on K-562 cancer cell line were modeled to illustrate the quantitative structure–activity relationship (QSAR) of the compounds. The dataset were divided into training and test set through Kennard-stone algorithm, while the pool of molecular descriptors calculated with paDEL descriptor metric program was subjected to the genetic functional algorithm (GFA) for selection of descriptor to be modeled. The best QSAR model developed was then subjected to a rigorous statistical test. The statistical significance of the model was verified by calculating the values of Q2LOO (0.845), Q2F1 (0.9397), Q2F2 (0.6862) and R2pred (0.6862) needed to evaluate the strength and robustness of the model. The result of the internal and external validation of the model indicates that the model is good and could be used to predict the GI50 of anticancer compounds on K-562 leukemia cell line. The model developed was used in designing new anticancer drugs with higher activity or more potent and less toxic in nature when compared to the lead compound. These compounds significant activities were found to correlate to with some of the molecular descriptors such as the number of hydrogen bond acceptors present in the surface of the molecule.

Insilico Modelling of Quantitative Structure-Activity Relationship of Pgi50 Anticancer Compounds on k-562 Cell Line

Abstract The pGI50 cytotoxicity values of 112 compounds on K-562 cancer cell line were modelled in order to illustrate the quantitative structure–activity relationship of the compounds. The data set were divided into training and test set through Kennard-stone algorithm, while the pool of molecular descriptors calculated with paDEL descriptor metric program was subjected to genetic functional algorithm for selection of descriptor to be modeled. The statistical significance of the model was verified by calculating the values of Q2LOO (0.845), Q2F1 (0.9397), Q2F2 (0.6862) and R2pred (0.6862) needed to evaluate the strength and robustness of the model. The result of the internal and external validation of the model indicates that the model is good and could be used to predict the GI50 of anticancer compounds on K-562 leukemia cell line.

In-vitro Evaluation of Aqueous Extracts of Citurs sinensis, Aloe vera and Their 1:1 Extracts Blend on Protein Denaturation during Acute Inflammation

Abstract Citrus sinensisand Aloe veraare well known and widely used herbs, which contains several interesting bioactive constituents and possesses health promoting properties. Oxidative stress contributes to the pathogenesis and progression of many diseases. The use of natural antioxidant, as a therapeutic option, is desirable and increasingly being practised. The aim of the present study is to evaluate and compare the antiinflammatory effects of aqueous extracts of Citrus sinensisand Aloe veraand a 1:1 blend of the two extracts against the denaturation of protein in vitro. The test extracts of varying concentrations were incubated with egg albumin under controlled experimental conditions and subjected to determination of absorbance to assess the anti-inflammatory property. A standard anti-inflammatory drug, Ibuprofen, was used as reference drug. The results obtained exhibited a concentration- dependent inhibition of protein (albumin) denaturation by both extracts, including the 1:1 blend of the extracts. From the present findings, it can be concluded that both Citrus sinensisand Aloe verapossessed a marked anti-inflammatory effect against the denaturation of protein, in vitro. Aloe verawas found to be slightly more active than Citrus sinensis, possibly due to the higher flavonoids contents of Aloe vera.