Bioassay-guided isolation of a vasorelaxant active compound from Kaempferia galanga L.

Bioassay-guided fractionation was performed on a crude dichloromethane extract of Kaempferia galanga L. using chromatography techniques. Screening of the extract for biological activity started with the brine shrimp lethality bioassay, followed by the study of its antihypertensive activity on anaesthetized rats, which involved monitoring of the extract's effect on mean arterial blood pressure. The components of the fractions obtained from the separation procedures were analyzed using gas chromatography (GC). The yield of the CH(2)Cl(2) extract was 0.29% of the crude plant extract. Analysis of the data for brine shrimp lethality test using the Finney computer program showed that this extract exhibited potent bioactivity with an ED(50) value of 7.92+/-0.13 microgml(-1). Intravenous administration of the extract induced a dose-related reduction of basal mean arterial pressure (MAP) (130+/-5 mmHg) in the anaesthetized rat, with maximal effects seen after 5-10 min of injection. The gas chromatogram showed that the common compound in the active fractions obtained from the bioassay-guided fractionation of the CH(2)Cl(2) extract was ethyl cinnamate. This vasorelaxant active compound, ethyl cinnamate, was isolated as a colorless oil. Ethyl p-methoxycinnamic acid was also isolated as white needles but did not exhibit any relaxant effect on the precontracted thoracic rat aorta.     

4-Phenylcoumarins from Mesua elegans with acetylcholinesterase inhibitory activity

A significant acetylcholinesterase (AChE) inhibitory activity was observed for the hexane extract from the bark of Mesua elegans (Clusiaceae). Thus, the hexane extract was subjected to chemical investigation, which led to the isolation of nine 4-phenylcoumarins, in which three are new; mesuagenin A (1), mesuagenin C (3), mesuagenin D (4) and one new natural product; mesuagenin B (2). The structures of the isolated compounds were characterized by spectroscopic data interpretation, especially 1D and 2D NMR. Four compounds showed significant AChE inhibitory activity, with mesuagenin B (2) being the most potent (IC(50)=0.7μM).     

Ionic liquid-based microwave-assisted extraction of lipid and eicosapentaenoic acid from Nannochloropsis oceanica biomass: experimental optimization approach

Journal of Applied Phycology - Lipids and eicosapentaenoic acid (EPA) compounds from Nannochloropsis oceanica biomass were extracted using a combination of ionic liquids (ILs) and...     

Metabolomics and molecular marker analysis to explore pepper (Capsicum sp.) biodiversity

An overview of the metabolic diversity in ripe fruits of a collection of 32 diverse pepper (Capsicum sp.) accessions was obtained by measuring the composition of both semi-polar and volatile metabolites in fruit pericarp, using untargeted LC–MS and headspace GC–MS platforms, respectively. Accessions represented C. annuum, C. chinense, C. frutescens and C. baccatum species, which were selected based on variation in morphological characters, pungency and geographic origin. Genotypic analysis using AFLP markers confirmed the phylogenetic clustering of accessions according to Capsicum species and separated C. baccatum from the C. annuum–C. chinense–C. frutescens complex. Species-specific clustering was also observed when accessions were grouped based on their semi-polar metabolite profiles. In total 88 semi-polar metabolites could be putatively identified. A large proportion of these metabolites represented conjugates of the main pepper flavonoids (quercetin, apigenin and luteolin) decorated with different sugar groups at different positions along the aglycone. In addition, a large group of acyclic diterpenoid glycosides, called capsianosides, was found to be highly abundant in all C. annuum genotypes. In contrast to the variation in semi-polar metabolites, the variation in volatiles corresponded well to the differences in pungency between the accessions. This was particularly true for branched fatty acid esters present in pungent accessions, which may reflect the activity through the acyl branch of the metabolic pathway leading to capsaicinoids. In addition, large genetic variation was observed for many well-established pepper aroma compounds. These profiling data can be used in breeding programs aimed at improving metabolite-based quality traits such as flavour and health-related metabolites in pepper fruits.     

Development of a Polygonum minus cell suspension culture system and analysis of secondary metabolites enhanced by elicitation

Polygonum minus has been reported to contain valuable metabolites and to date, there is no report on using cell culture technique for metabolite production in P. minus. Naphthalene acetic acid (NAA) concentrations in the range of 2–6 mg L^?1 were used in a matrix of combinations with dichlorophenoxyacetic acid (2,4-D) concentrations in the range of 2–10 mg L^?1 as plant growth regulators (PGRs) to induce callus cultures. Media that were supplemented with 2 mg L^?1 2,4-D + 4 mg L^?1 NAA, 2 mg L^?1 2,4-D + 6 mg L^?1 NAA and 6 mg L^?1 2,4-D + 8 mg L^?1 NAA were effective for callus induction (93.3 % of the explants produced callus). To establish cell culture, the best growth was obtained from medium that was supplemented with 1 mg L^?1 2,4-D + 2 mg L^?1 NAA. From a 1-g inoculum size, the fresh weight increases exponentially after 5–10 days of culture, and a 26.71 g maximum fresh weight was obtained after 25 days of culture. The cell culture medium was then analyzed using gas chromatography–mass spectrometry (GC–MS). Jasmonic acid (100, 50, 25 and 5 μM), salicylic acid (100, 50, 25 and 5 μM), yeast extract (500, 250 and 100 mg L^?1) and glass beads were used in this research as elicitors. The cell cultures were then incubated with the different elicitors for 1, 2, 3 and 4 days. Several compounds with high peak area percentages were detected, including 2-furancarboxaldehyde, 5-hydroxymethyl, furfural, and 2-cyclopenten-1-one, 2-hydroxy. These results show the diversity of metabolites released by P. minus cell into the culture medium under control conditions.     

Phylotype classification of Ralstonia solanacearum biovar 1 strains isolated from banana (Musa spp) in Malaysia

During 2011–2012, 15 bacterial isolates were obtained from wilting banana plants from seven locations in Malaysia. Characterisation of the Malaysian isolates was determined by biovar determination, pathogenicity test, phylotype-specific multiplex PCR (Pmx-PCR) and endoglucanase (egl) gene amplification. Based on the genotype, phenotype and pathogenic characteristics, all isolates were identified as Ralstonia solanacearum. Pmx- and egl-PCRs indicated that all isolates belong to phylotype II of Ralstonia species complex hierarchical classification. The neighbour joining phylogenetic tree of egl sequences also verified the results where the isolates were all clustered into phylotype II, together with the reference sequences strains, UW070 and UW162. Therefore, the results of our study may provide a better understanding on the taxonomy of R. solanacearum species occupying banana plantations in Malaysia. This study is indeed the first report of phylotype II classification of R. solanacearum biovar 1 strains isolated from banana plants in Malaysia.     

Ethnic Differences in the Prevalence of Metabolic Syndrome: Results from a Multi-Ethnic Population-Based Survey in Malaysia

Introduction

The prevalence of metabolic syndrome is increasing disproportionately among the different ethnicities in Asia compared to the rest of the world. This study aims to determine the differences in the prevalence of metabolic syndrome across ethnicities in Malaysia, a multi-ethnic country.

Methods

In 2004, we conducted a national cross-sectional population-based study using a stratified two-stage cluster sampling design (N = 17,211). Metabolic syndrome was defined according to the International Diabetes Federation/National Heart, Lung and Blood Institute/American Heart Association (IDF/NHLBI/AHA-2009) criteria. Multivariate models were used to study the independent association between ethnicity and the prevalence of the metabolic syndrome.

Results

The overall mean age was 36.9 years, and 50.0% participants were female. The ethnic distribution was 57.0% Malay, 28.5% Chinese, 8.9% Indian and 5.0% Indigenous Sarawakians. The overall prevalence of the metabolic syndrome was 27.5%, with a prevalence of central obesity, raised triglycerides, low high density lipoprotein cholesterol, raised blood pressure and raised fasting glucose of 36.9%, 29.3%, 37.2%, 38.0% and 29.1%, respectively. Among those <40 years, the adjusted prevalence ratios for metabolic syndrome for ethnic Chinese, Indians, and Indigenous Sarawakians compared to ethnic Malay were 0.81 (95% CI 0.67 to 0.96), 1.42 (95% CI 1.19 to 1.69) and 1.37 (95% CI 1.08 to 1.73), respectively. Among those aged ≥40 years, the corresponding prevalence ratios were 0.86 (95% CI 0.79 to 0.92), 1.25 (95% CI 1.15 to 1.36), and 0.94 (95% CI 0.80, 1.11). The P-value for the interaction of ethnicity by age was 0.001.

Conclusions

The overall prevalence of metabolic syndrome in Malaysia was high, with marked differences across ethnicities. Ethnic Chinese had the lowest prevalence of metabolic syndrome, while ethnic Indians had the highest. Indigenous Sarawakians showed a marked increase in metabolic syndrome at young ages.     

Cytotoxic triterpenoids from the bark of Aglaia smithii (Meliaceae)

Two new dammarane triterpenoids, aglinone (1) and aglinin E (20S,24S-epoxy-25-hydroxy-1-en-dammarene) (2) along with three known compounds, 3-epiocotillol (3), aglinin A (4), and eichlerianic acid (5), were isolated from the bark of Aglaia smithii. The chemical structures of the new compound were elucidated on the basis of spectroscopic data interpretation. All the compounds isolated were evaluated for their cytotoxic effects against P-388 murine leukemia cells. Compounds 1, 2, 4 and 5 showed cytotoxicity against P-388 murine leukemia cells with IC₅₀ values of 21, 42, 34, and 11 μg/mL, respectively.     

Analysis of Salmonella Agona and Salmonella Weltevreden in Malaysia by PCR fingerprinting and antibiotic resistance profiling

Forty-eight strains of Salmonella enterica subsp. enterica serovar Agona and 33 strains of Salmonella enterica subsp. enterica serovar Weltevreden were characterized by random amplified polymorphic DNA (RAPD) fingerprinting using 3 different arbitrary primer, Enterobacterial Repetitive Intergenic Consensus-Polymerase Chain Reaction (ERIC-PCR) and antimicrobial susceptibility testing. By using RAPD, 81 strains (44 strains of S. Agona and 33 strains of S. Weltevreden) can be clustered into 14 groups and 6 single isolates whereas ERIC-PCR produced 7 clusters and 3 single isolates. Thirteen antimicrobial agents were used and all the isolates were resistant to erythromycin and showed Multiple Antimicrobial Resistance indexes, ranging from 0.08 to 0.62. Poultry still remain as the common reservoir for multi-drug-resistant Salmonella. On the other hand, vegetables contaminated with S. Weltevreden showed a gain in antimicrobial resistance. Besides that, consistent antibiograms were observed from S. Weltevreden isolated at Kajang wet market on 2000/08/02.