Chemical Science International Journal
EISSN : 2456-706X
Published by: Sciencedomain International (10.9734)
Total articles ≅ 329
Latest articles in this journal
Published: 25 November 2021
Chemical Science International Journal pp 1-9; https://doi.org/10.9734/csji/2021/v30i1030255
The content of Mn, Zn, Ni, Cu, Fe, and Pb in 10 samples of Kappaphycus alvarezii (cottonii) and 10 samples of Eucheuma denticulatum (spinosum) from 15 different sites in the intertidal coastal area of Zanzibar were determined by using EDXRF. The heavy metals assessed in both species decreased in the order of Fe >Mn > Zn >Pb> Cu > Ni. In general, the cottonii samples in Unguja had significantly higher (p ≤ 0.05) concentrations of Fe, Zn, Ni, Cu and Pb than the spinosum samples, but the latter had significantly higher levels of Mn. Similarly, the cottonii samples in Pemba had significantly higher (p ≤ 0.05) concentrations of Ni, Cu and Pb than the spinosum samples, but the latter had significantly higher levels of Fe and Zn. The concentrations of heavy metals in cottonii and spinosum in the present study were noticed lower compared to publish results. The results from this study revealed that, the heavy metals contaminations in cottonii and spinosum along the coastal area in Zanzibar were mainly caused by effluents that directly flow into marine environments. Hence, serious measures should be taken to reduce the flow of waste effluents into the marine ecosystem.
Published: 18 November 2021
Chemical Science International Journal pp 52-60; https://doi.org/10.9734/csji/2021/v30i930254
Aims: The objective of this work is to determine the chemical composition and in vitro evaluation of the antibacterial activities of essential oils of four species of aromatic plants of Gabonese origin obtained by hydrodistillation. Methods: All the samples were examined by chromatographic analyzes and by GC / MS coupling. Antimicrobial activity was assessed by diffusion and microdilution methods. Results: The most common compounds found in essential oils were terpene hydrocarbons and oxygenates. The major constituents are β-phellandrene (56.3%), β-pinene (11%) and myrcene (10.4%). The three bacterial strains used are sensitive to essential oils. However, some essential oils stood out with greater spectra of action compared to others, such as Maranthes gabunensis and Mammea africana which showed activity against all strains. The inhibition parameters (MIC and CMB) are between 0.78 and 25 mg / mL. Some oils have shown bacteriostatic and / or bactericidal activity on the targeted strains. Conclusion: The essential oils studied present a diversity of chemical compositions and good antibacterial activities.
Published: 17 November 2021
Chemical Science International Journal pp 39-51; https://doi.org/10.9734/csji/2021/v30i930253
Aim: To evaluate water quality of the river Birim after a two-year ban as a result of illegal mining activities in the catchment areas of the river. Methodology: Samples were taken during wet and dry seasons in acid-washed plastic containers. Two water quality indices were adapted for the river under study and used in the evaluation. These were Water Quality Index (WQI) and Heavy Metal Pollution Index (HPI). Twelve physicochemical parameters, such as pH, turbidity, conductivity, total suspended solids, total dissolved solids, total hardness, alkalinity, sulphate, phosphate, nitrate, Fluoride, and chloride which were life-threatening and generally acceptable in water quality were used to evaluate the water quality index. The computed WQI was 439.168, which fell within the unfit for drinking category with turbidity and total suspended solids positively influencing the index. Iron, (Fe), As, Mn, and Hg were used to evaluate HPI, with an index value of 39.49, which was excellent considering a critical value of 100 set, below which the water is fit for good drinking water. Conclusion: Except for heavy metal pollution, the river Birim is unfit for drinking without chemical treatment and that, the two-year ban on artisanal small-scale mining was not enough for the river to recover fully from previous pollution episodes and hence did not have any impact on water quality of the river Birim.
Chemical Science International Journal pp 30-38; https://doi.org/10.9734/csji/2021/v30i930252
Essential oil from peels of lemon (Citrus Lumion) fruit had been evaluated for its physiochemical, phytochemical compositions and application in skin-care product. Lemon peel oil, which is one of the under-utilized essential oil was isolated from the matured fruits peel using petroleum ether by soxhlet extraction method. The percentage yield of 3.7 %, for air-dried peels and 2.30 %, for fresh peels are acceptable for most plants essential oils. The ash content of both the dried and fresh peels were 1.42 ± 0.001 and 4.007±0.003. Some phytochemicals like, saponins, flavonoids, terpenes, carbohydrates, tannins, were determined using standard methods. The lemon-peel-oil skin-lotion formulation was carried out by mixing 5 ml of the peel oil sample with corresponding mass of basic lotion compositions, in water base-tank, and homogenously mixed in oil base-tank under 700 C. The pH range(6.30), viscosity, spreadability, and properties of the lotion were compared to the non-lemon-oil lotion and to a commercial grade skin lotion.
Chemical Science International Journal pp 16-29; https://doi.org/10.9734/csji/2021/v30i930251
The aim of this work is to develop a new method for the analysis of agmatine from UV-Visible absorption spectra. The optimization of the analytical parameters shows that the stoichiometry of the orthophthalaldehyde-agmatine complex is 1:1, the optimal pH is equal to 11 and the stability time is about 10 minutes. The analytical performances obtained are satisfactory with very low limit of detection (LOD) and limit of quantification (LOQ) respectively equal to 0.121 µg/mL and 0.405 µg/mL. The relative standard deviation (RSD) obtained of 2.1% shows the good reproducibility of the measurements. Interference effects show that the aromatic biogenic amines interfere less than linear ones, excepted serotonine. Similarly, a more marked interference is found for chloride salts. Finally, a recovery rate of between 99.4% and 111.7% was found in the grape extract studied, showing the effectiveness of the method.
Chemical Science International Journal pp 1-15; https://doi.org/10.9734/csji/2021/v30i930250
The propane oxidative dehydrogenation (ODH) reaction has been considered as an alternative method for propene production owing to its exothermic nature, which renders it environmentally friendly. The use of alkaline promoters for supported V catalysts can increase propene selectivity and partially inhibit the formation of CO and CO2. Our goal was to evaluate the promoting effect of K and Na and the support effect using gibbsite as precursor for the propane ODH reaction. Catalysts were prepared via co-impregnation of V and alkali metals on a previously prepared alumina support and were characterized using N2 adsorption-desorption, X-ray diffraction, temperature-programmed reduction, and isopropanol decomposition tests to evaluate their acid-base properties. The activity of the synthesized catalysts for the propane ODH reaction was evaluated at the O2:C3H8:He molar ratios of 5:2:4, 6:1:4, and 4:3:4. The addition of alkali metals to the V catalysts increased propane conversion and propene selectivity; moreover, both parameters increased with increasing molar fraction of O2 in the reactants. K doping increased the propene selectivity of the doped catalysts, because it inhibited a large fraction of catalytic surface acidic sites. A high molar fraction of O2 in the reactants facilitated the regeneration of the catalyst, whereas a high reoxidation rate improved catalytic activity and propene selectivity.
Chemical Science International Journal pp 39-46; https://doi.org/10.9734/csji/2021/v30i830248
Aims: The aim of present study to evaluate the antioxidant potential of Abrus precatorius Linn leaves ethanol extract containing bioactive compounds on free radical scavenger using DPPH. Ethanol extract of Abrus precatorius Linn leaves was subjected to preliminary phytochemical screening and fraction of extract was detected by Gas Chromatography-Mass Spectrometry analysis. Methodology and Results: GC-MS analysis of ethanol leaves extract was carried out on Shimadzu GC-MS model number QP 2010S and revealed the presence of 18 phytochemical compounds, with mome inositol as a dominant component. Antioxidant potential of leaves ethanol extract was evaluated using DPPH free radical scavenging assay at five different doses as 5, 10, 20, 30, 40 and 50 μg/mL and showed significant DPPH free radical scavenging potential with the IC50 value of 33.37 μg/mL. The bioautography of extract showed that fractions with the most prominent antioxidant potential tended to contain secondary metabolites reported in preliminary phytochemical screening such as alkaloids, carbohydrates, protein and amino acids, glycoside, tannins, flavonoids, triterpenoids and phenolic compounds. The results evaluate and justify the traditional relevance of Abrus precatorius Linn leaves ethanol extract for free radical scavenging potential as a antioxidant and can be used as a lead for the isolation of the antioxidant bioactive chemical constituents in further study. Conclusion: Preliminary phytochemical screening reported various bioactive compounds in the ethanol extract of Abrus precatorius Linn leaves and identified by GC-MS. The extract exhibited greater free radical scavenging activity i.e. antioxidant potential. The presence of various bioactive phytocompounds justifies the therapeutic use of the Abrus precatorius Linn plant leaves for various ailments by traditional practitioners.
Chemical Science International Journal pp 47-56; https://doi.org/10.9734/csji/2021/v30i830249
Background: Benzimidazole constitutes a starting point for the development of new antiprotozoal agents since this nucleus exists in several pharmacologically significant molecules, in particular possessing antifungal, antiviral, antibacterial, and antiparasitic properties. Objective: The present study aimed to identify a molecular hit likely to be developed as an anti-leishmanial and antitrypanosomal drug candidate. Methods: Thus, 12 hybrids of chalcone or benzimidazolyl-arylpropenones were synthesized and screened in vitro for anti-leishmanial activity against promastigotes of Leishmania donovani. The microculture tetrazolium assay was used to determine their potential to inhibit 50% of a parasite growth (IC50). Results: Two compounds among 5-chlorobenzimidazole-chalcones (4a and 4c), which exhibited potent activity (IC5050 μM) were selected to check their trypanocidal activity. Lethal concentration (LC100) values of these compounds were estimated by using observations on the viability of trypomastigotes of Trypanosoma brucei brucei in MEM medium with Earle’s salts and L-glutamine. Seven of the tested compounds (4a, 4b, 4c, 4e, 4g, 4h, and 4j) showed particularly higher inhibitory activity than pentamidine (IC50= 7.6 μM) against L. donovani promastigotes with IC50 values in a range from 0.5 to 1.8 μM. In addition, the 2’-chlorine derivative (4c), displayed potent anti-trypanosomal activity comparable to those of melarsoprol, used as reference drug. Conclusion: These results support this series of benzimidazole holding arylpropenone group in position 2 as a starting point for future optimization to get novel agents active against leishmaniasis and trypanosomiasis.
Chemical Science International Journal pp 25-38; https://doi.org/10.9734/csji/2021/v30i830246
An understanding of the principles of complex equilibria and species distribution in different solutions is important in expounding and correlating the interaction of different ligands with different metal ions in complex formation. Therefore, acid-base equilibria involved in the formation of binary and ternary complexes of Co (II), Cu (II) and Pb (II) with methionine (Met) and uracil (Urc) have been determined by potentiometric titration technique. The stability constants of the complexes were evaluated at 35 ± 0.1°C and 0.02 M ionic strength (kept constant with NaNO3) in aqueous and organic-aqueous media. The species distribution in solutions as a function of pH was determined using the Hyss program. The stability of the ternary complexes relative to the corresponding binary complexes of the secondary ligand is measured in terms ΔlogK and % RS values. The ternary complexes are observed to be more stable than binary complexes in the media except for [CuMetUrc] ternary complex in organic-aqueous medium where the ternary complex is less stable than the binary complex of the uracil. The overall stability of the ternary complexes was higher in organic-aqueous system than aqueous system. The stability of the complexes was found to be correlated with the covalent index of the metal ions and Jahn Teller distortion. pH-studies of these systems revealed an increase in the concentrations of the ternary complexes with increase in pH. The formation of binary complexes was shown to be favoured in physiological pH range (3-7) while that of the ternary complexes is observed to be favoured in the pH range 5-10.
Chemical Science International Journal pp 1-12; https://doi.org/10.9734/csji/2021/v30i830244
The purpose of this study is to develop a QSAR model predictive of the antimalarial activity of a series of Dihydrothiophenone molecules using quantum chemical methods. The molecules were optimized from the B3LYP/6-31G (d, p) level of theory. The extracted descriptors are the vibrational frequency of the carbonyl group (Ѵ(C=O)), enthalpy of formation (Δ f H°), the valence angle between the carbon-nitrogen-carbon atoms α(C-N-C) and the ionization potential (I); The application of the RLM method of the XLSTAT program allowed us to develop a regression model. The statistical indicators (R²=93.50%, S=0.211, F=43.678) of the developed model attest to its robustness and reliability. Internal and external validation parameters (Q2loo et Q2ext) reveal that the established model performs well in predicting the antimalarial activity of the series of molecules studied. It can therefore be used to design new HD molecules belonging to its field of applicability at a 95% confidence level.