Brief review on polymeric materials concerning degradable polymers

The demand for cutting-edge functional materials has been increasing since the decade. Polymeric materials usage in the past decade contributes to its commercial accomplishment, thus encouraging more groundbreaking research-based activities. Although this news is promising for polymer-related industries, the fast consumption rate of these materials throughout the world will seriously harm the environment through the accumulation of waste materials sourced primarily from by-products, faulty products or municipal from various agricultural farms and industries with disposal difficulties. Wide usage of polymeric materials is due to their ease of processing, light weight and relatively low manufacturing cost. Various advancements were made over the years in developing polymeric materials of high performance. Structure and ionic bonds of polymeric and biomaterials are the reason behind their physical and chemical properties. However, their usage is limited due to expensive manufacturing cost and difficulty in shaping and processing them

Chemical constituents and lipoxygenase inhibitory activity of Piper stylosum Miq.

ABSTRACT. Chemical constituents and lipoxygenase inhibitory activity of the aerial part of Piper stylosum have been studied. Fractionation and purification of the extracts afforded five lignans, identified as yangambin (1), sesamin (2), syringaresinol (3), pinoresinol (4), and medioresinol (5), together with other constituents; 4-allyl resorcinol, β-sitosterol, β-sitostenone, taraxerol, vanilin, and vanilic acid. The structures of these compounds were established by analysis of their spectral data, as compared to that of reported compounds. The lipoxygenase inhibitory activity of the extracts and isolated lignans were also evaluated.               KEY WORDS: Piperaceae, Piper, Piper stylosum, Lignan, Lipoxygenase Bull. Chem. Soc. Ethiop. 2019, 33(3), 587-592.   DOI: https://dx.doi.org/10.4314/bcse.v33i3.1

Mercury (II) removal using CNTS grown on GACs

Elemental (metallic) mercury primarily causes health effects when it is breathed as a vapor where it can be absorbed through the lungs, at higher exposures there may be kidney effects, respiratory failure and death. This study aimed to study the performance of carbon nanotubes (CNT) grown on granular activated carbon (GAC) as an adsorbent for removal of mercury from aqueous solution. Due to its highly toxic effects to humans and environment, heavy metal concentrations in water are restricted by strict standards and reduced to the standard permitted. The effect of pH, agitation speed,contact time and CNT dosage was studied for optimal adsorption of mercury in the aqueous solution. Design Expert software was used to determine the number of runs and its variations,which are 18 runs. It was found that the optimal condition for mercury (II) ions adsorption occurred at adsorbent dosage of 5 mg, pH value of 5, contact time of 120 minutes and agitation speed of 150 rpm. The model resulted R2= 0.8517 indicating 85.17% of the factors,which were pH, contact time,agitation speed and adsorbent dosage correlated to each other

Chemical constituents and acetylcholinesterase inhibitory activity of Beilschmiedia insignis Gamble

ABSTRACT. Secondary metabolites from natural products are potential sources of acetylcholinesterase inhibitors, which are key enzymes in the treatment of many neurodegenerative diseases. Inspired by the reported activities of alkaloids herein we report the chemical investigation on the chemical constituents from Beilschmiedia insignis and their acetylcholinesterase inhibitory activity. Isolation of the stem bark of B. insignis led to the isolation and identification of five aporphine alkaloids, namely isocorydine (1), norisocorydine (2), (+)-laurotetanine (3), (+)-N-methyllaurotetanine (4), and (+)-boldine (5), together with β-sitosterol (6), β-sitostenone (7), lupeol (8), and lupenone (9). The chemical structures of these compounds were obtained by analysis of their spectroscopic data, as well as the comparison with that of reported data. Acetylcholinesterase inhibitory activity revealed that all isolated alkaloids were found to inhibit AChE with percentage inhibition values ranged from 44.9 to 74.5%. This is the first report on phytochemicals from B. insignis.                     KEY WORDS: Lauraceae, Beilschmiedia insignis, Alkaloid, Acetylcholinesterase, Alzheimer   Bull. Chem. Soc. Ethiop. 2021, 35(3), 685-691. DOI: https://dx.doi.org/10.4314/bcse.v35i3.1

Alkaloids from the genus Dehaasia: phytochemistry and biological activities

The genus Dehaasia is one of the genera of evergreen trees or shrubs belong to Lauraceae, and comprise about 35 species of tree that are distributed worldwide. The purpose of this review is to provide an update and comprehensive information on the phytochemistry and pharmacological research of Dehaasia species in order to explore their therapeutic potential and evaluate future research opportunities. All the available information on Dehaasia species was actualized systematically by searching the scientific literatures databases such as PubMed, SciFinder, Web of Science, and Google Scholar. From the data collected in this review, the genus Dehaasia has attracted much attention due to their richness in alkaloids with various bioactivities, and it comprises a wide range of therapeutically promising plants. Therefore, a detailed study and clinical evaluation of Dehaasia species should be carried out in future for the safety approval of therapeutic applications

The influence of carbonization temperature on the development of carbon membrane with superior CO2/CH4 separation performance Pengaruh suhu karbonisasi kepada pembangunan membran karbon dengan kesan pemisahan gas CO2/CH4 yang cemerlang

In this study, P84-based carbon tubular membranes were fabricated and characterized in terms of their structural morphology and gas permeation properties, by using Scanning Electron Microscopy (SEM) and pure gas permeation system, respectively. The polymer tubular membranes were then carbonized under nitrogen atmosphere at different carbonization temperatures of 600, 700, 800 and 900 °C, with heating rate of 3°C/min and thermal soak time of 30 minutes. The manipulation of carbonization temperatures was required to see if it could enhance the permeation properties as desired. Pure gas permeation tests were performed using CO2 and CH4 gases. The CO2/CH4 selectivity was found increasing as the carbonization temperature was increased from 600 to 800 °C. The carbon membrane carbonized at 800°C showed the most promising result for CO2/CH4 selectivity, rendering 69.48 and CO2 permeance of 206.1 GPU

Phytochemistry and biological activities of the genus Ocotea (Lauraceae): a review on recent research results (2000-2016)

Ocotea (family: Lauracea), which comprises nearly 350 species, are distributed throughout tropical America, Africa, and Asia. Up to now, the reported constituents from the genus Ocotea involve neolignans, alkaloids, sesquiterpenes, flavonoids, lignans, butanolides, benzopyrans, steroids, essential oils and several other types of compounds (alkylphenols, arylpropene, coumarin, ester, saponin). Studies have shown that Ocotea and its active principles possess a wide range of pharmacological activities, such as anti-inflammatory, cytotoxicity, antimicrobial, larvicidal, and antiproliferative activities. The outcome of these studies will further support the therapeutic potential of the genus Ocotea, and provide convincing evidences to its future clinical applications in modern medicine. Thus, increasing amount of data supports application and exploitation for new drug development

P84 co-polyimide-based tubular carbon membrane: effect of pyrolysis temperature

In this study, the effect of carbonization temperature on the performance of carbon membrane was being investigated. P84 co-polyimide-based tubular carbon membrane were fabricated through the dip-coating technique. The prepared membranes were characterized by using the thermogravimetric analysis and scanning electron microscopy. CO2, N2, and CH4 pure gas were utilized in determination of the carbon membrane’s permeation attributes. In order to enhance the membrane’s performance, carbonization process was performed in Ar environment; with the flow rate of 200 ml/min. The carbonization process was done at various temperature, namely 600 oC, 700 oC, 800 oC and 900 oC in a constant heating rate of 3 oC/min. The increased in the temperature of carbonization leads to the production of small pores size carbon membrane. Carbon membrane prepared at 800 oC showed the highest CO2/CH4 and CO2/N2 selectivity of 63.2±5.2 and 61.3±1.7, respectively

Chemical constituents and acetylcholinesterase inhibitory activity of Piper abbreviatum Opiz

Plants of the genus Piper have long been used as medicinal herbs. The chemistry of Piper species has been widely investigated and phytochemical investigations conducted in all parts of the world have led to the isolation of a number of physiologically active compounds. Thus, this study was carried out to investigate the phytochemicals from Piper abbreviatum and their acetylcholinesterase inhibitory activity, which has not been previously investigated. Fractionation and purification of the aerial parts of P. abbreviatum led to the isolation and identification of five methoxylated flavonoids, namely 5,7-dimethoxyflavone, 4ʹ,5,7-trimethoxyflavone, 3',4',5,7-tetramethoxyflavone, 5-hydroxy-7-methoxyflavone, 5-hydroxy-4ʹ,7-dimethoxyflavone, together with lupeol, lupenone, β-sitosterol, and β-sitostenone. The structures of these compounds were obtained by analysis of their spectroscopic data, as well as the comparison with that of reported data. Acetylcholinesterase inhibitory activity revealed that all isolated flavones were found to inhibit AChE with percentage inhibition values ranged from 24.2 to 58.2%. This is the first report on the isolation of methoxylated flavonoid from P. abbreviatum. The high variants of flavonoid compounds from this species may be used as chemotaxonomic markers for this Piper species.                     KEY WORDS: Piperaceae, Piper, Piper abbreviatum, Flavonoid, Acetylcholinesterase   Bull. Chem. Soc. Ethiop. 2020, 34(3), 625-632. DOI: https://dx.doi.org/10.4314/bcse.v34i3.1

Photocatalytic disinfection of bacteria under visible light irradiation by BiFeO3 photocatalyst

BiFeO3 nanoparticles was synthesized by sol gel auto combustion. The as-synthesized BiFeO3 were characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectra (DRS) and Brunauer-Emmett-Teller (BET) analysis. The disinfection activities towards Gram-positive Staphylococcus aureus (S.aureus) were examined under visible light irradiation. The results showed a complete inactivation of 3 × 106 CFU/mL S.aureus was achieved within 20 min. The disruption of bacterial cell structure was observed by Transmission electron microscope (TEM). The cells were severely damaged after being exposed to BiFeO3 under visible light irradiation. Hence, the results demonstrated the potential application of perovskite-type photocatalyst, BiFeO3 in photocatalytic disinfection of various microorganisms