Water-extractable Fraction Research Articles

Humification characterization of biochar and its potential as a composting amendment

Biochar has received increasing attention due to its applications as a soil amendment. Here, the chemical properties of solid and water-extractable fractions of four biochar samples were investigated. The results showed that wood biochar and bamboo biochar samples were 60%–80% more hydrophobic than those of rice husk biochar and rice husk ash. In addition, the acidity was 3.88 mmol/g from the total functional groups and 1.03 mmol/g from the carboxyl groups/lactones/phenols found in the wood biochar sample, which were about 1.5 times greater than those of the bamboo biochar sample. These functional groups could be used to determine the sorptive capacity of biochar for ionic solutes and water content and to increase the degradation of compost organics. The wood biochar sample was found to have the most humification materials (fulvic acid-like material + humic acid-like material) in the water-extractable fraction, which was 3–10 times higher than that in the rice husk biochar and rice husk ash; humified materials were not detected in the bamboo biochar sample. Humification materials in biochar may be involved in increasing the proportion of humic acid-like materials in humic-like substances within the compost product. Wood biochar had better hydrophobic, sorptive, aromatic, and humification properties compared to other biochars, suggesting that it may be used in composting in order to exert its effect as both a bulking agent and a composting amendment during the solid waste composting process.

Subcellular distribution and chemical form of Pb in hyperaccumulator Arenaria orbiculata and response of root exudates to Pb addition

Solution culture was conducted in order to understand accumulation characteristics and chemical forms of Pb in Arenaria orbiculata (A. orbiculata) and the response of root exudates to Pb addition. The results showed that: 1) Pb contents in the shoot and root of A. orbiculata increased with increasing in Pb concentrations in solution. 2) The contents of Pb chemical forms under Pb addition followed as: HAc extractable fraction (F HAC )> HCl extractable fraction (F HCl )> NaCl extractable fraction (F NaCl )> ethanol-extractable fraction (F E )>water extractable fraction (F W ). 3) Increased Pb level in the medium caused increases in Pb contents in the four subcellular fractions of shoots and roots, with most accumulation in FIV (Fraction IV, soluble fraction) in shoots and FI (Fraction I, cell wall fraction) in roots. 4) Contents of soluble sugar and free amino acid of root exudates increased with increasing Pb concentration in solution. Significantly positive correlations between Pb and contents of soluble sugar and free amino acid were observed. 5) With Pb concentrations in solution, low molecular weight organic acids (LMWOAs) contents followed the tendency: tartaric acid>acetic acid>malic acid>citric acid. Significantly positive correlation was observed between Pb and citric acid contents. The results indicate that soluble sugars, free amino acid and citric acid in root exudates of A.orbiculata facilitate the absorption and accumulation of Pb, which exist in NaCl-, HCl- and HAc- extractable Pb forms, FI and FIV fractions, resulting in tolerance of A.orbiculata to Pb.

How soil organic matter composition controls hexachlorobenzene–soil-interactions: Adsorption isotherms and quantum chemical modeling

Hazardous persistent organic pollutants (POPs) interact in soil with the soil organic matter (SOM) but this interaction is insufficiently understood at the molecular level. We investigated the adsorption of hexachlorobenzene (HCB) on soil samples with systematically modified SOM. These samples included the original soil, the soil modified by adding a hot water extract (HWE) fraction (soil+3 HWE and soil+6 HWE), and the pyrolyzed soil. The SOM contents increased in the order pyrolyzed soil<original soil<soil+3 HWE<soil+6 HWE. For the latter three samples this order was also valid for the HCB adsorption. The pyrolyzed soil adsorbed more HCB than the other samples at low initial concentrations, but at higher concentrations the HCB adsorption became weaker than in the samples with HWE addition. This adsorption combined with the differences in the chemical composition between the soil samples suggested that alkylated aromatic, phenol, and lignin monomer compounds contributed most to the HCB adsorption. To obtain a molecular level understanding, a test set has been developed on the basis of elemental analysis which comprises 32 representative soil constituents. The calculated binding energy for HCB with each representative system shows that HCB binds to SOM stronger than to soil minerals. For SOM, HCB binds to alkylated aromatic, phenols, lignin monomers, and hydrophobic aliphatic compounds stronger than to polar aliphatic compounds confirming the above adsorption isotherms. Moreover, quantitative structure–activity relationship (QSAR) of the binding energy with independent physical properties of the test set systems for the first time indicated that the polarizability, the partial charge on the carbon atoms, and the molar volume are the most important properties controlling HCB–SOM interactions.

First Ayurvedic Approach Towards Green Drugs: Anti Cervical Cancer-Cell Properties of Clerodendrum viscosum Root Extract

The concept of Ayurvedic expert guided drug discovery and development is defined and put to test systematically for the first time in literature. Western Science has explored only ~5% of the approximately 25,000 species of higher plants for drug leads. The ancient medical science of Ayurveda has however employed a much larger spectrum of plants for clinical treatment. Clerodendrum viscosum (CV), a commonly growing weed in the Indian subcontinent has been employed by S. Nirmalananda (Ayurvedic expert) for the treatment of cervical cancer. Here we isolate and characterize a water extract fraction (Cv-AP) from the root of CV and evaluate its anticervical cancer cell bioactivity. Our results indicate that Cv-AP possesses pro-apoptotic, anti-proliferative, and anti-migratory activity in a dose-dependent fashion against cervical cancer cell lines. In contrast, primary fibroblasts (control healthy cells), when exposed to similar concentrations of this extract, fail to undergo apoptosis and remain relatively unaffected. These findings suggest that Clerodendrum viscosum (CV) is a readily available source of components with potent anti-cancer activity and selective bioactivity against cervical cancer cells. The major component in CV-AP was identified as a glycoprotein via SDS Page and Concanavalin-A binding studies. This study serves to illustrate that systematic collaboration with Ayurveda is a practical and powerful strategy in drug discovery and development.

Exploring the Biodegradation Potential of Polyethylene Through a Simple Chemical Test Method

Oxidatively degradable polyethylene is finding widespread use, particularly in applications such as single use packaging and agriculture. However, the key question which still remains unanswered is the ultimate fate and biodegradability of these polymers. During a short-time frame only the oxidized low molecular weight fraction will be amenable to significant biodegradation. The short-time frame biodegradation potential of different LDPE-transition metal formulations was, thus, explored through a simple chemical extraction of oxidized fraction. In addition the effectiveness of different transitions metals was evaluated by comparing the extractable fractions. Blown LDPE films modified with different transition metal based pro-oxidants were thermo-oxidized at 60 °C over extended periods. The structural changes occurring in the polymer were monitored and the oxidized degradation products formed as a result of the aging process were estimated by extractions with water and acetone. The extractable fraction first increased to approximately 22 % as a result of thermo-oxidative aging and then leveled off. The extractable fraction was approximately two times higher after acetone extraction compared to extraction with water and as expected, it was higher for the samples containing pro-oxidants. Based on our results in combination with existing literature we propose that acetone extractable fraction gives an estimation of the maximum short-term biodegradation potential of the material, while water extractable fraction indicates the part that is easily accessible to microorganisms and rapidly assimilated. The final level of biodegradation under real environmental conditions will of course be highly dependent on the specific environment, material history and degradation time.

Mechanism for the disparity of the lipid production by Trichosporon fermentans grown on different sweetpotato vines hydrolysates

The enzymatic hydrolysate of sweetpotato vines (SVH) has been proved to be an effective substrate for lipid production of Trichosporon fermentans. This study proposed that the lipid production efficiencies could be remarkably different among different SVHs, although these SVHs were prepared from the samples of the same species. The plant samples for producing SVH-1 and SVH-2 belong to the same species but were harvested in 2011 and 2012, respectively. However, the maximum lipid yield was 9.6gl−1 by using SVH-1 but only 5.6gl−1 by using SVH-2. eSVH-2 was prepared from a hot water extracted sweetpotato vines of 2012. Although the maximum lipid yields in all the SVH-1, SVH-2 and eSVH-2 treatments increased after glucose addition, the promoting effects of glucose addition on the lipid accumulation were not effective in the SVH-2 and eSVH-2 treatments. Combined analysis of the SVHs composition and the different biochemical behaviors of T. fermentans suggested that different levels of carbon and nitrogen in the SVHs were the main causes for the disparity of lipid production. The water extractable fraction of sweetpotato vines was also essential for the promoting effect of SVHs. The removal of water extract resulted in the lack of active components that can stimulate the lipid accumulation. This work provides valuable information about the effects of composition of SVHs on lipid production, which is helpful for the optimization of lipid fermentation from sweetpotato vines.

Different Land Use Intensities in Grassland Ecosystems Drive Ecology of Microbial Communities Involved in Nitrogen Turnover in Soil

Understanding factors driving the ecology of N cycling microbial communities is of central importance for sustainable land use. In this study we report changes of abundance of denitrifiers, nitrifiers and nitrogen-fixing microorganisms (based on qPCR data for selected functional genes) in response to different land use intensity levels and the consequences for potential turnover rates. We investigated selected grassland sites being comparable with respect to soil type and climatic conditions, which have been continuously treated for many years as intensely used meadows (IM), intensely used mown pastures (IP) and extensively used pastures (EP), respectively. The obtained data were linked to above ground biodiversity pattern as well as water extractable fractions of nitrogen and carbon in soil. Shifts in land use intensity changed plant community composition from systems dominated by s-strategists in extensive managed grasslands to c-strategist dominated communities in intensive managed grasslands. Along the different types of land use intensity, the availability of inorganic nitrogen regulated the abundance of bacterial and archaeal ammonia oxidizers. In contrast, the amount of dissolved organic nitrogen determined the abundance of denitrifiers (nirS and nirK). The high abundance of nifH carrying bacteria at intensive managed sites gave evidence that the amounts of substrates as energy source outcompete the high availability of inorganic nitrogen in these sites. Overall, we revealed that abundance and function of microorganisms involved in key processes of inorganic N cycling (nitrification, denitrification and N fixation) might be independently regulated by different abiotic and biotic factors in response to land use intensity.

Water Leaching of Chelated Pb Complexes from Post-Phytoremediation Biomass

There is a pollution risk when disposing of post-remediation biomass from chelate-assisted metal phytoremediation. To assess this risk, we measured water extractable lead (Pb) in Brassica rapa tissues with ICP-MS, determined if chelated Pb was present with HPLC-MS, and identified Pb storage locations using electron microscopy with x-ray microanalysis. Ethylenediaminetetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (EDDS) were used to enhance Pb movement from contaminated soil to above ground B. rapa tissues. With Pb-EDTA, 92 % (+/−5) of Pb was water extractable from dried tissues and complexed as Pb-EDTA. Electron microscopy and x-ray microanalysis showed Pb stored in xylem vessels. After composting of plant tissues, 79 % (+/−2) of Pb was water extractable and complexed as Pb-EDTA. Total plant Pb accumulation was lower from soils amended with EDDS, but only 6.7 % (+/−0.3) of Pb was water extractable from dried tissues and 55 % (+/−25) from wet tissues of plants grown in EDDS-amended soils. Pb-EDDS was detected in tissues but not at quantifiable levels. This work emphasizes the need for proper treatment and disposal of contaminated post-remediation plant tissues, especially when using EDTA. Composting of plant tissues containing Pb-EDTA was shown to significantly reduce waste material volume and slightly reduce the water extractable fraction, but further immobilization of Pb would be necessary to minimize transport risk. Amending Pb-contaminated soils with EDDS can result in plant biomass with a lower potential to leach Pb into groundwater, but the lower Pb accumulation with EDDS would require longer phytoremediation time compared with EDTA.

Anti-oxidant and anti-inflammatory activity of leaf extracts and fractions of Mangifera indica

ObjectiveTo evaluate the anti-oxidant and anti-inflammatory activity of leaf extracts and fractions of Mangifera indica in in vitro conditions. MethodsIn vitro DPPH radical scavenging activity and lipoxygenase (LOX) inhibition assays were used to evaluate the anti-oxidant and anti-inflammatory activities respectively. Methanolic extract (MEMI), successive water extract (SWMI) and ethyl acetate fraction (EMEMI), n-butanol fraction (BMEMI) and water soluble fraction (WMEMI) of methanolic extract were evaluated along with respective reference standards. ResultsIn in vitro DPPH radical scavenging activity, the MEMI, EMEMI and BMEMI have offered significant antioxidant activity with IC50 values of 13.37, 3.55 and 14.19 μg/mL respectively. Gallic acid, a reference standard showed significant antioxidant activity with IC50 value of 1.88 and found to be more potent compared to all the extracts and fractions. In in vitro LOX inhibition assay, the MEMI, EMEMI and BMEMI have showed significant inhibition of LOX enzyme activity with IC50 values of 96.71, 63.21 and 107.44 μg/mL respectively. While, reference drug Indomethacin also offered significant inhibition against LOX enzyme activity with IC50 of 57.75. Furthermore, MEMI was found to more potent than SWMI and among the fractions EMEMI was found to possess more potent antioxidant and anti-inflammatory activity. ConclusionsThese findings suggest that the MEMI and EMEMI possess potent anti-oxidant and anti-inflammatory activities in in vitro conditions.

Active substances and in vitro anti-diabetic effects of a traditional folk remedy Bian-Que Triple-Bean Soup as affected by the boiling time

Bian-Que Triple-Bean Soup (Bian-Que San Dou Yin in Chinese) is a folk remedy which has been used for thousands of years in the practices of traditional Chinese medicine. The objectives of the current study were aimed to determine in vitro anti-diabetic effects and to find out the optimal cooking time for retaining active substances. α-Glycosidase in vitro inhibitory capacities and DPPH free radical scavenging capacities, and contents of active substances including total phenolics, saponin, tannin and monomeric anthocyanin, were determined with colorimetric methods. The results revealed that Bian-Que Triple-Bean Soup boiled for 30 min has the most effective impact on α-glycosidase inhibition. n-Butanol-soluble and water extract fractions showed relatively higher α-glycosidase inhibitory activity (17.4% and 11.2%, respectively) than that (2.56% and 5.32%, respectively) of hexane-soluble and dichloromethane-soluble fractions. Degradation was observed for those thermally unstable substances (TPC, tannin, and anthocyanin) by extending the boiling time; however, there were no obvious changes for thermo-stable substances (saponin).

Inhibitory Effects of Polysaccharides on the Cariogenic Activities ofStreptococcus mutans

Many carbohydrates are involved in the biofilm formation and activities of glucosyltransferases (Gtfs) of Streptococcus mutans, and the effects of various disaccharides and polysaccharides were investigated in this study, including the hot water-extracted glucan fraction of the Lentinula edodes fruiting body (HWG). HWG was found to inhibit the initial adhesion of S. mutans to saliva-coated hydroxyapatite (sHA), and also laminarin to inhibit glucan synthesis by Gtfs. However, sucrose-dependent biofilm formation by S. mutans was not inhibited by these materials. Interestingly, dextran was found to have an inhibitory effect on the sucrose-dependent biofilm formation. The data suggest that the presence of such an edible glucan as dextran in daily foods would act to some degree on S. mutans for suppressing the cariogenic activity.

Analysis Toward Innovative Herbal Antibacterial &amp; Antifungal Drugs

The antimicrobial activities of four medicinal plants Argemona mexicana, Achyranthes aspera, Catharanthus roseus, and Syzygium cumini were evaluated against Escherichia coli, Vibrio cholerae, Klebsiella pneumoniae, Proteus vulgaris, Bacillus subtilis, Salmonella typhi and three Aspergillus species. Extracts from Achyranthes aspera and Catharanthus roseus showed the highest antimicrobial potential (MIC 0.375-0.750 mg/ml) while extract from Argemona mexicana and Syzygium cumini, showed less activity. In disc diffusion assay, only eight out of twenty extracts showed antimicrobial activity at a concentration of 25.0 μg/ disc. The GCMS investigation reveals the existence of 2-bornanone; 1, 2-benzenedicarboxylic acid, bis (2-methylpropyl) ester; hexadecanoic acid, methyl ester and hexatriacontane in water extract fraction of C. roseus. The present research article provides a review of some medicinal plants incorporating antimicrobial drugs, together with recent advances in emerging therapeutics in clinical development and related patents for exploitation of herbal medicine.

Enhanced DPPH radical scavenging activity and DNA protection effect of litchi pericarp extract by Aspergillus awamoribioconversion

BackgroundLitchi (Litchi chinensis Sonn.) pericarp is a major byproduct which contains a significant amount of polyphenol. This study was designed to biotransformation litchi pericarp extract (LPE) by Aspergillus awamori to produce more bioactive compounds with stronger antioxidant activities.ResultsThe study exhibited that the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities significantly (p < 0.05) increased from 15.53% to 18.23% in the water-extracted fraction and from 25.41% to 36.82% in the ethyl acetate-extracted fraction. Application of DNA cleavage assay further demonstrated the enhanced protection effect of the fermented phenolics on DNA damage. It is also noted that the water-extracted fraction of the fermented LPE possessed a much stronger capacity than the ethyl acetate-extracted fraction to prevent from damage of supercoiled DNA. Interestingly, it was found that some new compounds such as catechin and quercetin appeared after of A. awamori fermentation of LPE, which could account for the enhanced antioxidant activity.ConclusionThe DPPH radical scavenging activity and DNA protection effect of LPE were increased by Aspergillus awamori bioconversion while some compounds responsible for the enhanced antioxidant activity were identified. This study provided an effective way of utilizing fruit pericarp as a readily accessible source of the natural antioxidants in food industry and, thus, extended the application area such as fruit by-products.

Contribution of coffee proteins to roasted coffee volatiles in a model system

SummaryA simple roasting model using a mineral oil bath was set up to study the effects of coffee proteins on the formation of coffee volatiles during roasting. Green coffee powder was separated into four fractions, and the highest concentration of volatile compounds was observed in the roasted sample of the water extract fraction. Sugar degradation products were the dominant compounds. The addition of coffee proteins into the nonprotein water extract fraction catalysed sugar degradation and enhanced the production of selected volatiles. Higher amounts of coffee protein correlated with the concentration of pyrazines. Coffee protein also increased sucrose degradation in the roasting of sucrose with coffee protein. However, the results from colour measurements indicated that a greater amount of protein produced a lighter colour. These results demonstrated the important contribution of coffee proteins in the formation of coffee volatiles and colour.

Phytochemical screening, mineral and proximate composition of Asteracantha longifolia leaf extracts as a quality livestock feed

Fractions of hot water extract of Asteracantha longifolia Nees leaf and aerial parts were subjected to qualitative and quantitative screening of different phytochemicals and for quantitative determination of different micro and macro elements. Dried leaf powder was analyzed for proximate composition and quantitative determination of different micro and macro elements. Proximate composition of the leaf revealed 14.212±0.375% of ash, 18.413±0.258% of protein, 3.401±0.081% of ether extract and 41.205±0.573% of fiber. Qualitative phytochemical screening of fractions of hot water extract of leaves revealed the presence of alkaloids, carbohydrates, proteins, phenolic compounds and flavonoids in all the fractions in addition to presence of proteins containing aromatic amino acids in aqueous fraction. Total phenolic compounds and total antioxidants in all the three fractions were in the range of 0.094 to 0.14 mg of gallic acid equivalent mg-1 extract and 40.95 to 317.5 µM of ascorbic acid equivalent mg-1 extract, respectively. Relatively low concentration of total antioxidant was found in residual fraction. Flavonoid concentrations were found in the range of 0.17±0.03 to 3.17±0.04 mg of quercetin equivalent g-1 extract, highest being the aqueous fraction and lowest the residual fraction. The residual fraction was found to contain a higher concentration of iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), calcium (Ca), magnesium (Mg) and phosphorus (P). The level of sodium (Na) and potassium (K) were higher in methanolic fraction and hot water extract, respectively. The incorporation of A. longifolia can be a potential source of antioxidant, macro and micro minerals for manufacturing nutraceutical and improving livestock feed. Key words: Qualitative, quantitative, phytochemical screening, mineral, antioxidant, phenolics.

Study on the medicinal plant Calandula officinalis

The antibacterial and anti-fungal activities of the methanol and its sub fractions of chloroform, ethyl acetate, and water extracts of the roots, stem and leaves of Calendula officinalis were carried out against bacterial strains, Staphylococus aureus, Klebsiella pneumoniae, Salmonella typhymurium and Escherichia coli, and fungal species including Aspergilla fumigates, Fusarium solani, Aspergillus niger, and Aspergilla flavus. Phytochemical analysis was also performed using the literature methods. The studied medicinal plant extracts against the tested bacterial strain, C. officinalis showed very promising results against both the Gram positive and Gram negative bacterial and fungal species. The significant antibacterial activity of active extracts was compared with the standard antimicrobics, gentamicin (10 µg/disc). The methanolic extracts showed inhibitory effects of 16 mm each of the stem and leaves samples against S. typhymurium and S. aureus. The water extract of leaves has 17 mm against S. typhymuriumand very high activity among all the extracts 18 mm inhibition of the roots against E. coli. The antifungal activity of the extracts showed significantly variable results against the tested fungal strains. Phytochemical studied indicated that the roots, stem and leaves contain secondary metabolites such as alkaloids, flavonoids, saponins, anthraquinone, terpenoids, tannins ,reducing sugar, cardiac glycosides etc. These phytochemicals are present predominantly in the roots, stem and leaves of C. officinalis. A fluorescence characteristic of the roots stem and leaves powders and their extracts were also investigated. Key words: Antibacterial, Calendula officinalis, phytochemicals.

Water-extractable soil organic matter characterization by chromophoric indicators: Effects of soil type and irrigation water quality

Use of treated wastewater (TWW) for irrigation may affect the concentration and composition of dissolved organic matter (DOM) in the soil solution. Our objectives were (i) to characterize the water-extractable fraction of soil organic matter (SOM) in terms of chromophoric DOM (CDOM) for different soil types and irrigation water qualities, and (ii) to examine the possible relations between DOM composition and various soil properties. Aqueous extracts from four different soil types irrigated with either secondary TWW or fresh water (FW) were characterized for dissolved organic carbon (DOC) concentration and absorbance at 254nm (Abs254). Excitation–emission matrices (EEM) of fluorescence were determined in these aqueous extracts and in extracts where DOM was separated into acid-soluble and acid-precipitated fractions. Parallel factor (PARAFAC) analysis of the EEMs of water-extractable DOM and their fractions identified two humic-like fluorescent components and one tryptophan-like component and provided their concentration scores. The concentration scores revealed that the acid-soluble DOM fraction contained the greater part of the humic-like fluorescent components present in the bulk DOM samples. Statistical examination demonstrated that the ratio of the concentration score of the humic-like substances that emit light at shorter wavelengths to that of humic-like substances that emit light at longer wavelengths was higher in the acid-soluble DOM fraction compared to the acid-precipitated DOM fraction. Among the FW-irrigated soils, the soil extracts varied in terms of concentration of DOM components. Irrigation of the coarse-textured soils with TWW generally increased the concentrations of DOC, fluorescent components and Abs254 in comparison to irrigation with FW. In the fine textured soils TWW application led to a decrease or had no impact on the concentration of DOC and the CDOM components in water-extractable SOM. Thus, the influence of TWW irrigation on water-soluble SOM relative to that of FW irrigation was also soil dependent. Strong linear relations (/r/>0.7) were found within CDOM indicators including concentration scores of fluorescent components and Abs254. Weak or no relations were found (i) between DOC concentration and CDOM indicators, and (ii) between attributes related to DOM properties and basic soil properties. Hence, nor DOC concentration neither SOM content can be used for estimating changes in concentrations of chromophoric components in water-extractable DOM.

Pedogenic, lithogenic – or anthropogenic origin of Cr, Ni and V in soils near a petrochemical facility in Southeast Mexico

Abstract Large Cr, V and Ni contents were found in soils near Cd. Pemex in Tabasco, Mexico. Their origin was hypothesized to be either anthropogenic, derived from emissions of a petrochemical facility, or lithogenic, from the volcanic ash deposited by the “El Chichon” volcano, or accumulated residually by pedogenesis. We proved these possible origins by analyzing composite samples taken from the soil surface at different distances from the facility as well as samples from two soil profiles located close and far away from the facility within the same land unit, i.e. Acrisols developed on Miocene marine terraces. The sites located far away from the facility were closer to the volcano, and therefore supposedly more affected by the ash deposition. All samples were analyzed for their total metal content and profile samples for their different metal fractions. Additionally the soil microstructure, mineralogy and elemental composition of particular pedogenic features were studied in thin sections from the different soil horizons. Results evidenced that the emissions from the petrochemical facility do not contribute significantly to the total concentration of Cr, Ni and V in the adjacent soils. Nickel was found in the soil in concentrations between 39 and 318 mg kg− 1; particularly large contents of this element were associated to volcanic ash additions visualized in the thin sections. Micromorphological analyses of nodule like pebbles found in both profiles evidenced that these features are laterite fragments transported from preexisting soil. The matrix of these fragments is enriched with Cr and V (3000–7000 mg kg− 1 of Cr, and 1000–3000 mg kg− 1 V), and these elements are actually translocated into relatively newly formed iron concretions found within these laterites and reaching concentrations of up to 10,000–17,000 mg kg− 1 Cr. The fractionation showed that Cr and V were dominantly associated to crystalline iron oxides and to the residual fraction; water extractable, exchangeable and EDTA extractable fractions were below detection limits ( We conclude that the studied elements are of lithogenic and pedogenic origin; they were enriched dominantly through residual accumulation by lateritization, probably of mesozoic ultramafic rocks from the margins of the Caribbean plate, and later fragmented and transported by water to the present location; only Ni was also partly added by the recent volcanic activity.

Polysaccharide peptides from Coriolus versicolor competitively inhibit model cytochrome P450 enzyme probe substrates metabolism in human liver microsomes

Polysaccharide peptide (PSP), isolated from COV-1 strain of Coriolus versicolor, is commonly used as an adjunct in cancer chemotherapy or health supplement in China. Previous studies have shown that PSP decreased antipyrine clearance and inhibited rat CYP2C11-mediated tolbutamide 4-hydroxylation and in human CYP2C9. In this study, the effects of the water extractable fraction of PSP on the metabolism of model CYP1A2, CYP2D6, CYP2E1 and CYP3A4 probe substrates were investigated in pooled human liver microsomes. PSP (1.25–20μM) dose-dependently decreased CYP1A2-mediated metabolism of phenacetin to paracetamol (IC50 19.7μM) and CYP3A4-mediated metabolism of testosterone to 6β-hydroxytestosterone (IC20 7.06μM). Enzyme kinetics studies showed the inhibition of CYP1A2 activity was competitive and concentration-dependent (Ki=18.4μM). Inhibition of testosterone to 6β-hydroxytestosterone was also competitive and concentration-dependent (Ki=31.8μM). Metabolism of dextromethorphan to dextrorphan (CYP2D6-mediated) and chlorzoxazone to 6-hydroxychlorzoxazone (CYP2E1-mediated) was only minimally inhibited by PSP, with IC20 values at 15.6μM and 11.9μM, respectively. This study demonstrated that PSP competitively inhibited the CYP1A2- and CYP3A4-mediated metabolism of model probe substrates in human liver microsomes in vitro. The relatively high Ki values for CYP1A2 and CYP3A4 would suggest a low potential for PSP to cause herb–drug interaction related to these CYP isoforms.

Antibacterial potential of benzoate and phenylethanoid derivatives isolated from Acanthus ilicifolius L. leaf extracts

The antibacterial activities of column chromatography fractions of n-hexane, benzene, chloroform, acetone, ethanol and water extracts from Acanthus ilicifolius were tested against 24 bacterial pathogens. The antibacterial activity was performed using agar diffusion method. Most active fractions were further investigated through UV-Vis, 13C, 1H-NMR, FT-IR for the structural elucidation. The antibacterial activity of the extracts was identified as 6-hydroxy-benzoxazolinone, (Z)-4-coumaric acid 4-O-β-D-glucopyranoside and 3,5-dimethoxy-4-hydroxy methyl benzoate.