GREEN SYNTHESIS OF PLANT-MEDIATED METAL NANOPARTICLES: THE ROLE OF POLYPHENOLS

The use of metal nanoparticles (MNPs) in various fields is increasing day-by-day leading to a genuine concern about the issues related to their environmental and biological safety. The major approaches for the synthesis of NPs include physical and chemical methods which are expensive and hazardous to health in addition to being toxic to the environment. This review highlights the potential of plant extracts to carry out the synthesis of MNPs with a special emphasis on the role of flavonoids in nanosynthesis. This green and clean approach have been actively utilized in recent years as an alternative to conventional hazardous approaches. It has proved as cost-effective, non-toxic, less time and labor consuming, efficient, and eco-friendly method for the synthesis of MNPs with specific biological actions. This review also focuses on the role of polyphenols, including the flavonoids as bioreductants of metal salts for the synthesis of NPs along with their biomedical applications. Various examples of the MNPs, along with their biological actions, have also been summarized

Development of bambangan (Mangifera pajang) carbonated drink

Mangifera pajang Kostermans or bambangan is a popular fruit among Sabahan due to its health and economic values. However, the fruit is not fully commercialized since it is usually been used as traditional cuisine by local people. Thus, development of bambangan fruit into carbonated drink was conducted to produce new product concept. The objectives of this study were to conceptualize, formulate, evaluate consumer acceptance, and determine physicochemical properties and nutritional composition of the accepted product. Method used in conceptualising the product was based on questionnaire. The consumer acceptance was evaluated based on descriptive and affective tests with four product formulations tested. The physicochemical properties on carbon dioxide volume, colour, pH, total acidity, total soluble solid (TSS) and viscosity were highlighted, meanwhile nutritional composition on fat, protein, carbohydrates and energy content were determined. About 77% respondents gave positive feedback, and 69% respondents decided this product is within their budget. The formulation of 5% bambangan pulp, 70% water, 25% sugar and 0.2% citric acid was highly accepted in descriptive and affective tests with 4.4 and 6.39 mean scores, respectively. The physicochemical properties and nutritional composition of the acceptance product were in optimum value except for colour, total acidity and TSS. Overall, this study showed that the product has high potential to be commercialized as new product concept, and heritage of indigenous people can be preserved when this fruit is known regionally

Determination of Level of Food Additives in Labisia Pumila (LP) Beverages Consumed in Kuantan, Malaysia

The content levels of several food additives (gallic acid, benzoic acid and caffeine) in commercial Labisia pumila (LP) beverage samples in Kuantan, Malaysia were determined by high performances liquid chromatography (HPLC). These analytical measurements were undertaken primarily to assess the compliance of content levels of the investigated food additives and their daily intake doses with permissible levels. The results obtained from this study indicated that the average levels of GA, caffeine and benzoic acid in the analyzed beverages were 37.62-229.35 ppm, 43.46 -168.00 ppm and 98.10-241.13 ppm, respectively. In addition, the concentrations of these food additives have been converted into daily intake doses based on beverage consumption. It was estimated that the mean daily intake of GA, caffeine and benzoic acid by the adult population of Kuantan through the consumption of the analyzed beverages were 0.39 mg/kg body weight/day for GA, 0.59 mg/kg body weight/day for caffeine (19.6 % ADI) and 0.43 mg/kg body weight/day for benzoic acid (8.6%ADI). None of the analyzed beverage sample was found to violate the current legal limits as stipulated in Malaysian food regulation

Antiproliferative activity of five garcinia species collected in Sabah, Malaysian Borneo against estrogen receptor-human breast carcinoma (MCF-7) cell line

Garcinia species are well-known for their unique properties of having natural secondary metabolite compounds called xanthone as well as their ethnomedicinal values such as antioxidant, anticancer, anti-inflammatory and antibacterial properties. The study was conducted to investigate the antiproliferative activity of peel, flesh and seed extracts of G. dulcis, G. parvifolia, G. nitida, G. mangostana var. mangosta and G. cambogia collected from Malaysian Borneo (Sabah) against estrogen receptor-positive human breast carcinoma (MCF-7) cells. The antiproliferative activity was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay. The results showed that G. dulcis seed induced strongest antiproliferative activity against MCF-7 cancer cell line with the IC50 value of 2.5±0.0 μg/ml, followed by G. dulcis flesh, G. mangostana var. mangostana peel and G. dulcis peel with IC50 values of 9.33 ± 3.21, 11.17 ± 1.04 and 17.67 ± 2.08 μg/ml, respectively. Meanwhile, the IC50 value for G. cambogia peel was 56.67 ± 10.5 μg/ml. No IC50 value was detected in all parts of G. parvifolia and G. nitida at concentration tested (<100 μg/ml). Overall, this study clearly showed that the whole fruit of G. dulcis displayed potent cytotoxic effect by inducing antiproliferative activity at low concentration. Further studies are needed in the future to develop this fruit as pharmaceutical and nutraceutical product for the treatment and prevention against cancer

Processing of Watermelon Rind Dehydrated Candy

Watermelon rind (Citrullus lanatus) dehydrated candy was prepared by using osmotic dehydration process that involves slow impregnation of syrup before drying at 50°C for 8, 14 and 20 hours. From the study, it can be seen that drying time significantly affected the moisture content of the watermelon rind dehydrated candy. The moisture content was significantly decreased with drying time. For colour evaluation, the L* value of watermelon rind dehydrated candy was slightly decreased with drying time while the a* value was slightly increased. Watermelon rind dehydrated candy that dried for 14 hours was the most preferred sample by the panelists as it received the highest score for texture, taste and overall acceptability attributes. So, it can be concluded that 14 hours of drying time is the most appropriate time to dry the candied watermelon rind

Next Generation Driver for Attosecond and Laser-plasma Physics

The observation and manipulation of electron dynamics in matter call for attosecond light pulses, routinely available from high-order harmonic generation driven by few-femtosecond lasers. However, the energy limitation of these lasers supports only weak sources and correspondingly linear attosecond studies. Here we report on an optical parametric synthesizer designed for nonlinear attosecond optics and relativistic laser-plasma physics. This synthesizer uniquely combines ultra-relativistic focused intensities of about 10(20)W/cm(2) with a pulse duration of sub-two carrier-wave cycles. The coherent combination of two sequentially amplified and complementary spectral ranges yields sub-5-fs pulses with multi-TW peak power. The application of this source allows the generation of a broad spectral continuum at 100-eV photon energy in gases as well as high-order harmonics in relativistic plasmas. Unprecedented spatio-temporal confinement of light now permits the investigation of electric-field-driven electron phenomena in the relativistic regime and ultimately the rise of next-generation intense isolated attosecond sources

Study on the biodegradability and water adsorption of ldpe/sago starch blend

The aim of this study is to develop starch incorperated with low density polyethylene (LDPE) composites with enhanced degradable properties. The degradable test has been carried out by hydrolysis. The water uptake of the composites has been determined. The degradability of the compatible thermoplastic LDPE/starch was investigated by weight loss percent (WLP). Simple and alkaline hydrolysis of the composites apparently involves surface starch granules; embedded granules are not easily accessible because of the poor moisture absorption of the matrix. Exposure of the composites to hydrolysis resulted in massive deterioration typified by turbidity, discoloration, embrittleness and dimensional changes. Moisture uptake increased with increased starch content and immersion time. The time taken for the composites to equilibrate was about three months even when they were immersed completely in water. The mechanical properties of the composite also dropped with increasing moisture uptake. SEM imaging was also carried out on the samples before and after degradation. High content of starch also was found to increase the rate of biodegradability of LDPE/sago starch mould

Effect of plasticizer on physical and mechanical properties of ldpe/sago starch blend

Starch-based polymeric materials offer a renewable, economical alternative to existing petroleum based, non-renewable or costly polymeric materials. The aim of this study is to develop degradable starch-low density polyethylene (LDPE) composites with enhanced mechanical properties. This research studies the effect of different kind of plasticizer. The compounding of the LDPE with sago starch was performed via a twin screw extruder followed by injection molding. Studies on their physical, mechanical of each formulation were carried out by density, melt flow index (MFI), tensile, flexural, impact. The presence of high starch contents had an adverse effect on the mechanical properties of LDPE/starch blends. However, the addition of compatibilizer or plasticizer improved the interfacial adhesion between the two materials, hence, improved the tensile properties of the blends. After using the proper composition and processing condition, mechanical properties of plasticized LDPE/SS blend are significantly higher than those of the unplasticized LDPE/SS blend with the same starch contents