Siti Hamidah Mohd. Setapar

Molecular mechanisms of drug photodegradation and photosensitization.

Drug-induced photosensitivity of the skin is drawing increasing attention. In past few decades, photosensitivity has been reported with an array of drugs, and is now recognized as a noteworthy medical problem by clinicians, regulatory authorities and pharmaceutical industry. The photosensitivity is of two types i.e., phototoxicity and photoallergy. Phototoxic disorders have a high incidence, whereas photoallergic reactions are much less frequent in human population. Several hundred substances, chemicals, or drugs may invoke phototoxic and photoallergic reactions. In order to avoid photosensitive reactions, it is essential to understand the mechanism behind the photosensitizing properties of such substances before these drugs are introduced in clinical settings. Photosensitization is inter-related to photochemical reaction, through the knowledge of which the photosensitivity of a drug can be anticipated. This review highlights the current research status on photosensitizing drugs and its correlation to phototoxicity. Different mechanisms of photodegradation of photolabile drugs have also been discussed.

Effect of heat treatment on copper removal onto manure-compost-activated carbons

The work was aimed to investigate the effect of heat treatment of manure-compost-based activated carbons on the adsorption of copper from aqueous solution. Activated carbons were characterized according to physical structures and surface functional groups. All equilibrium data of activated carbons formerly treated at different temperatures obeyed Langmuir model to linear approximation. Results showed that copper ions favorably adsorbed onto the mesopores at lower equilibrium concentrations and subsequently changed to the micropores at higher equilibrium concentrations. It was found that the increase in electron density upon heat treatment offered higher tendency for the uniform amount of protons to occupy the surface sites. Analysis of Scatchard plots suggested that the affinity driven by the mesopores toward copper ions was stronger than that of the micropores.

Dielectric relaxation process and microwave heating mechanism in ε- Caprolactone as a function of frequency and temperature

Dielectric properties of materials play a significant role in design of microwave assisted processing system. This paper is focused on the dielectric properties of ε-caprolactone (ε-cap) which is the monomer for the biodegradable polymer, Poly (ε-caprolactone) (PCL). The dielectric properties of ε-cap were measured across a wide range of frequencies (0.1 GHz5.0 GHz) and temperatures (20-150oC). Then the measured dielectric properties data was modelled using Debye model in order to relate quantitatively the dielectric properties to microwave heating mechanisms. The analysis carried out gives a clear picture of interaction of ε-cap with microwave energy and its heating mechanism in microwave assisted polymerisation process. This study concluded that microwave heating mechanism of the ε-cap in the measured range may be dominated by the dipole reorientation.

Essential Oils: Extraction Techniques, Pharmaceutical And Therapeutic Potential - A Review

BACKGROUND Essential oils are liquid extracts from aromatic plants, which have numerous applications in multiple industries. There are a variety of methods used for the extraction of essential oils, with each method exhibiting certain advantages and determining the biological and physicochemical properties of the extracted oils. Essential oils from different plant species contain more than 200 constituents which are comprised of volatile and non-volatile components. The application of essential oils as antimicrobial, anticancer, anti-inflammatory and anti-viral agents is due to their effective and efficient properties, inter alia. METHOD Several advanced (supercritical fluid extraction, subcritical extraction liquid, solvent-free microwave extraction) and conventional (hydrodistillation, steam distillation, hydrodiffusion, solvent extraction) methods have been discussed for the extraction of essential oils. Advanced methods are considered as the most promising extraction techniques due to less extraction time, low energy consumption, low solvent used and less carbon dioxide emission. CONCLUSION This manuscript reviewed the major research studies in the field and discussed several research findings on the chemical composition of essential oils, methods of oil extraction, and application of these oils in pharmaceutical and therapeutic fields. These essential oils can be used as anticancer, antimicrobial, antiviral, and as skin permeation enhancer agents.

Optimisation of supercritical CO2 extraction of red colour from roselle (Hibiscus Sabdariffa Linn.) calyces

Roselle (Hibiscus sabdariffa Linn.) is a local tropical plant widely cultivated in Malaysia. Roselle produces red edible calyces which contain intense red pigments of anthocyanins. Supercritical fluid extraction with carbon dioxide (CO2) is a particularly suitable isolation method for natural materials and gives an alternative to replace the mass usage of non-polar organic solvents in conventional methods. The advantage of using CO2 as solvent is that no organic solvent residual inside the extracted sample since CO2 is in gas form at room temperature. The red colour extract by using CO2 is easier to be separated by decompression and has high recovery percentage. The objective of this research was to optimise the supercritical carbon dioxide (SC-CO2) extraction conditions for obtaining the maximum yield of red colour extract. SC-CO2 extraction of red colour of roselle was performed with ethanol as modifier at the pressures of 8, 10 and 12 MPa, temperatures of 50, 60 and 70 °C while the percentage of modifier flow rates was at 5, 7.5 and 10 %. Full 33 factorial design was used to optimise operating conditions for the extraction yield of roselle calyces in SC-CO2.The other parameters were kept constant, such as total flow rate of CO2 and modifier (6 mL/min), ratio of modifier (75 % of ethanol), the average particle size used (350 μm) and extraction regime (70 min). The findings revealed that the extraction yield was significantly influenced by three main effects investigated in this study, with p-value smaller than 0.05. The optimum operating conditions obtained for SC-CO2 extraction of red colour extract were 8.90 MPa, 70 °C, and 9.49 % with predicted percentage yield of 26.73 %.