Biomass wastes produced from oil palm mills and plantations include empty fruit bunches (EFBs), shells, fibers, trunks, and oil palm fronds (OPF). EFBs and shells are partially utilized as boiler fuel while the rest of the biomass materials like OPF have not been utilized for energy generation. No previous study has been reported on gasification of oil palm fronds (OPF) biomass for the production of fuel gas. In this paper, the effect of moisture content of fuel and reactor temperature on downdraft gasification of OPF was experimentally investigated using a lab scale gasifier of capacity 50 kW. In addition, results obtained from equilibrium model of gasification that was developed for facilitating the prediction of syngas composition are compared with experimental data. Comparison of simulation results for predicting calorific value of syngas with the experimental results showed a satisfactory agreement with a mean error of 0.1 MJ/Nm³. For a biomass moisture content of 29%, the resulting calorific value for the syngas was found to be only 2.63 MJ/Nm³, as compared to nearly double (4.95 MJ/Nm³) for biomass moisture content of 22%. A calorific value as high as 5.57 MJ/Nm³ was recorded for higher oxidation zone temperature values.
Rapid industrial developments coupled with surging population growth have complicated issues dealing with water scarcity as the quest for clean and sanitized water intensifies globally. Existing fresh water supplies could be contaminated with organic, inorganic and biological matters that have potential harm to the society. Turbidity in general is a measure of water cloudiness induced by such colloidal and suspended matters and is also one of the major criteria in raw water monitoring to meet the stipulated water quality guidelines. Turbidity reduction is often accomplished using chemical coagulants such as alum. The use of alum is widely associated with potential development of health issues and generation of voluminous sludge. Natural coagulants that are available in abundance can certainly be considered in addressing the drawbacks associated with the use of chemical coagulants. Twenty one types of plant-based natural coagulants categorized as fruit waste and others are identified and presented collectively with their research summary in this review. The barriers and prospects of commercialization of natural coagulants in near future are also discussed.
Atherosclerosis is the process of hardening and narrowing the arteries. Atherosclerosis is generally associated with cardiovascular diseases such as strokes, heart attacks, and peripheral vascular diseases. Since the usage of the synthetic drug, statins, leads to various side effects, the plants flavonoids with antiartherosclerotic activity gained much attention and were proven to reduce the risk of atherosclerosis in vitro and in vivo based on different animal models. The flavonoids compounds also exhibit lipid lowering effects and anti-inflammatory and antiatherogenic properties. The future development of flavonoids-based drugs is believed to provide significant effects on atherosclerosis and its related diseases. This paper discusses the antiatherosclerotic effects of selected plant flavonoids such as quercetin, kaempferol, myricetin, rutin, naringenin, catechin, fisetin, and gossypetin.
Latent polyphenol oxidase (LPPO), an enzyme responsible for the browning reaction of sago starches during processing and storage, was investigated. The enzyme was effectively extracted and partially purified from the pith using combinations of nonionic detergents. With Triton X-114 and a temperature-induced phase partitioning method, the enzyme showed a recovery of 70% and purification of 4. 1-fold. Native PAGE analysis of the partially purified LPPO revealed three activity bands when stained with catechol and two bands with pyrogallol. The molecular masses of the enzymes were estimated by SDS-PAGE to be 37, 45, and 53 kDa. The enzyme showed optimum pH values of 4.5 with 4-methylcatechol as a substrate and 7.5 with pyrogallol. The LPPO was highly reactive toward diphenols and triphenols. The activity of the enzyme was greatly enhanced in the presence of trypsin, SDS, ethanol, and linoleic acid.
Nanotechnology is capturing great interest worldwide due to their stirring applications in various fields. Among nanoparticles (NPs), titanium dioxide (TiO2) NPs have been widely used in daily life and can be synthesized through various physical, chemical, and green methods. Green synthesis is a non-toxic, cost-effective, and eco-friendly route for the synthesis of NPs. Plenty of work has been reported on the green, chemical, physical and biological synthesis of TiO2 NPs and these NPs can be characterized through high tech. instruments. In the present review, dense data have been presented on the comparative synthesis of TiO2 NPs with different characteristics and their wide range of applications. Among the TiO2 NPs synthesis techniques, the green methods have been proven to be efficient than chemical synthesis methods because of the less use of precursors, time-effectiveness, and energy-efficiency during the green synthesis procedures. Moreover, this review describes the types of plants (shrubs, herbs and trees), microorganisms (bacteria, fungi and algae), biological derivatives (proteins, peptides, and starches) employed for the synthesis of TiO2 NPs. The TiO2 NPs can be effectively used for the treatment of polluted water and positively affected the plant physiology especially under abiotic stresses but the response varied with types, size, shapes, doses, duration of exposure, metal species along with other factors. This review also highlights the regulating features and future standpoints for the measurable enrichment in TiO2 NPs product and perspectives of TiO2 NPs reliable application.
A new tetraoxygenated xanthone, daphnifolin (1,3,5-trihydroxy-4-methoxyxanthone), along with three other xanthones, were isolated from the stem bark extracts of Mesua daphnifolia. Their structures were characterized on the basis of 1D and 2D NMR spectral data.
Nanoparticles (NPs) are nano-sized particles (generally 1⁻100 nm) that can be synthesized through various methods. The wide range of physicochemical characteristics of NPs permit them to have diverse biological functions. These particles are versatile and can be adopted into various applications, particularly in biomedical field. In the past five years, NPs’ roles in biomedical applications have drawn considerable attentions, and novel NPs with improved functions and reduced toxicity are continuously increasing. Extensive studies have been carried out in evaluating antibacterial potentials of NPs. The promising antibacterial effects exhibited by NPs highlight the potential of developing them into future generation of antimicrobial agents. There are various methods to synthesize NPs, and each of the method has significant implication on the biological action of NPs. Among all synthetic methods, green technology is the least toxic biological route, which is particularly suitable for biomedical applications. This mini-review provides current update on the antibacterial effects of NPs synthesized by green technology using plants. Underlying challenges in developing NPs into future antibacterials in clinics are also discussed at the present review.
Antimicrobial peptides (AMPs), the self-defence products of organisms, are extensively distributed in plants. They can be classified into several groups, including thionins, defensins, snakins, lipid transfer proteins, glycine-rich proteins, cyclotides and hevein-type proteins. AMPs can be extracted and isolated from different plants and plant organs such as stems, roots, seeds, flowers and leaves. They perform various physiological defensive mechanisms to eliminate viruses, bacteria, fungi and parasites, and so could be used as therapeutic and preservative agents. Research on AMPs has sought to obtain more detailed and reliable information regarding the selection of suitable plant sources and the use of appropriate isolation and purification techniques, as well as examining the mode of action of these peptides. Well-established AMP purification techniques currently used include salt precipitation methods, absorption-desorption, a combination of ion-exchange and reversed-phase C18 solid phase extraction, reversed-phase high-performance liquid chromatography (RP-HPLC), and the sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) method. Beyond these traditional methods, this review aims to highlight new and different approaches to the selection, characterisation, isolation, purification, mode of action and bioactivity assessment of a range of AMPs collected from plant sources. The information gathered will be helpful in the search for novel AMPs distributed in the plant kingdom, as well as providing future directions for the further investigation of AMPs for possible use on humans.
Infections by ESKAPE (Enterococcus sp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pathogens cause major concern due to their multi-drug resistance (MDR). The ESKAPE pathogens are frequently linked to greater mortality, diseases, and economic burden in healthcare worldwide. Therefore, the use of plants as a natural source of antimicrobial agents provide a solution as they are easily available and safe to use. These natural drugs can also be enhanced by incorporating silver nanoparticles and combining them with existing antibiotics. By focussing the attention on the ESKAPE organisms, the MDR issue can be addressed much better.
Phytosterols provide important health benefits: in particular, the lowering of cholesterol. From environmental and commercial points of view, the most appropriate technique has been searched for extracting phytosterols from plant matrices. As a green technology, supercritical fluid extraction (SFE) using carbon dioxide (CO2) is widely used to extract bioactive compounds from different plant matrices. Several studies have been performed to extract phytosterols using supercritical CO2 (SC-CO2) and this technology has clearly offered potential advantages over conventional extraction methods. However, the efficiency of SFE technology fully relies on the processing parameters, chemistry of interest compounds, nature of the plant matrices and expertise of handling. This review covers SFE technology with particular reference to phytosterol extraction using SC-CO2. Moreover, the chemistry of phytosterols, properties of supercritical fluids (SFs) and the applied experimental designs have been discussed for better understanding of phytosterol solubility in SC-CO2.
This study describes the chemical speciation of Pb, Zn, Cu, Cr, As, and Sn in soil of former tin mining catchment. Total five sites were selected for sampling and subsequent subsamples were collected from each site in order to create a composite sample for analysis. Samples were analysed by the sequential extraction procedure using optical emission spectrometry (ICP OES). Small amounts of Cu, Cr, and As retrieved from the exchangeable phase, the ready available for biogeochemical cycles in the ecosystem. Low quantities of Cu and As could be taken up by plants in these kind of acidic soils. Zn not detected in the bioavailable forms while Pb is only present in negligible amounts in very few samples. The absence of mobile forms of Pb eliminates the toxic risk both in the trophic chain and its migration downwards the soil profile. The results also indicate that most of the metals have high abundance in residual fraction indicating lithogenic origin and low bioavailability of the metals in the studied soil. The average potential mobility for the metals giving the following order: Sn > Cu > Zn > Pb > Cr > As.
A binary mixture of starch-starch or starch with other biopolymers such as protein and non-starch polysaccharides could provide a new approach in producing starch-based food products. In the context of food processing, a specific adjustment in the rheological properties plays an important role in regulating production processing and optimizing the applicability, stability, and sensory of the final food products. This review examines various biopolymer mixtures based on starch and the influence of their interaction on physicochemical and rheological properties of the starch-based foods. It is evident that the physicochemical and rheological characteristics of the biopolymers mixture are highly dependent on the type of starch and other biopolymers that make them up mixing ratios, mixing procedure and presence of other food ingredients in the mixture. Understanding these properties will lead to improve the formulation of starch-based foods and minimize the need to resort to chemically modified starch.
Free radical scavenging activity of 21 tropical plant extracts was evaluated using 1,1-diphenyl-2-picrylhydrazyl assay (DPPH). Total phenolic compounds and flavonoids were determined using Folin-Ciocalteu and HPLC, respectively. Results of the study revealed that all the plants tested exhibited excellent antioxidant activity with IC(50) in the range of 21.3 to 89.6 microg/mL. The most potent activity was demonstrated by Cosmos caudatus (21.3 microg/mL) and Piper betle (23.0 microg/mL) that are not significantly different than that of -tocopherol or BHA. L. inermis extract was found to consist of the highest concentration of phenolics, catechin, epicatechin, and naringenin. High content of quercetin, myricetin, and kaempferol were identified in Vitex negundo, Centella asiatica, and Sesbania grandiflora extracts, respectively. Luteolin and apigenin, on the other hand, were found in Premna cordifolia and Kaempferia galanga extracts. Strong correlation (R = 0.8613) between total phenolic compounds and total flavonoids (R = 0.8430) and that of antioxidant activity of the extracts were observed. The study revealed that phenolic, in particular flavonoids, may be the main contributors to the antioxidant activity exhibited by the plants.
Hypertension is one of the major risk factors for cardiovascular disease. Although various drugs for its treatment have been synthesized, the occurring side effects have generated the need for natural interventions for the treatment and prevention of hypertension. Dietary intervention such as the administration of prebiotics has been seen as a highly acceptable approach. Prebiotics are indigestible food ingredients that bypass digestion and reach the lower gut as substrates for indigenous microflora. Most of the prebiotics used as food adjuncts, such as inulin, fructooligosaccharides, dietary fiber and gums, are derived from plants. Experimental evidence from recent studies has suggested that prebiotics are capable of reducing and preventing hypertension. This paper will discuss some of the mechanisms involved, the evidence generated from both in-vitro experiments and in-vivo trials and some controversial findings that are raised.
Increased prevalence of methicillin-resistant Staphylococcus aureus (MRSA) has become a major threat to the health sector worldwide due to their virulence, limited therapeutic options and their distribution in both hospital and community settings. Discovery and development of new anti-MRSA agents as alternatives to the very few antibiotics left in the armamentarium are, thus, urgently required. Recently, an efflux mechanism in MRSA has been identified as one of the main contributors of resistance towards various structurally unrelated antibiotics. The potential of reserpine (a phytoalkaloid) as efflux pump inhibitor (EPI) against various microbes remains limited as the concentration needed for inhibition is toxic to humans. This study therefore aimed to evaluate 13 alkaloid compounds as potential inhibitory agents and/or potential EPIs against a panel of three MRSA isolates which not only differ in their susceptibility to vancomycin (amongst the last drugs available to treat serious MRSA infection), but also exhibited active efflux activity. Results indicated berberine's moderate inhibitiory activity against two MRSA isolates scoring a minimum inhibitory concentration (MIC) value of 125 microg/ml. Notable efflux inhibitory activity (ranging from two- to eightfold Ethidium Bromide MIC reduction) meanwhile was detected from quinine, piperine and harmaline using reserpine as the positive control. Findings from this study support the opinion that a vast number of potential phytocompounds with pharmacological potential await discovery. Therapeutic application of these compounds, however, warrants further investigation to ascertain their pharmacodynamics and safety aspects.
The application of low-cost adsorbents obtained from plant wastes as a replacement for costly conventional methods of removing heavy metal ions from wastewater has been reviewed. It is well known that cellulosic waste materials can be obtained and employed as cheap adsorbents and their performance to remove heavy metal ions can be affected upon chemical treatment. In general, chemically modified plant wastes exhibit higher adsorption capacities than unmodified forms. Numerous chemicals have been used for modifications which include mineral and organic acids, bases, oxidizing agent, organic compounds, etc. In this review, an extensive list of plant wastes as adsorbents including rice husks, spent grain, sawdust, sugarcane bagasse, fruit wastes, weeds and others has been compiled. Some of the treated adsorbents show good adsorption capacities for Cd, Cu, Pb, Zn and Ni.
The production of methanol from agricultural, forestry, livestock, poultry, and fishery waste via pyrolysis was investigated. Pyrolysis was conducted in a tube furnace at 450-500 °C. Sugarcane bagasse showed the methanol production (5.93 wt.%), followed by roots and sawdust with 4.36 and 4.22 wt.%, respectively. Animal waste offered the lowest content of methanol, as only 0.46, 0.80, and 0.61 wt.% were obtained from fishery, goat, and cow waste, respectively. It was also observed that the percentage of methanol increased with an increase in volatile compounds while the percentage of ethanol increased with the percentage of ash and fix carbon. The data indicate that, pyrolysis is a means for production of methanol and ethanol after further optimization of the process and sample treatment.
Six new sulfur-containing bis-iridoid glucosides, saprosmosides A-F (1-6), were isolated from the leaves of Saprosma scortechinii. From the stems of this same plant, two new iridoid glucosides, 3,4-dihydro-3-methoxypaederoside (8) and 10-O-benzoyldeacetylasperulosidic acid (12), were isolated. Their structures were elucidated by means of chemical, NMR, and mass spectroscopic methods. Additionally, 11 known iridoid glucosides were isolated and characterized as deacetylasperuloside, asperuloside, paederoside (7), deacetylasperulosidic acid (9), scandoside, asperulosidic acid, 10-acetylscandoside, paederosidic acid (10), 6-epi-paederosidic acid (11), methylpaederosidate, and monotropein. The structures of the new bis-iridoid glucosides were formed by intermolecular esterification between the glucose and carboxyl groups of three monomeric iridoid glucosides (7, 9, and 10).
Leaf extracts of Garcinia parvifolia provided relatively high yields of four novel, cytotoxic prenylated depsidones. The structures were determined mainly by detailed NMR spectral analysis and X-ray crystallography.