Spectaflavoside A, a new potent iron chelating dimeric flavonol glycoside from the rhizomes of Zingiber spectabile Griff

The rhizomes of Zingiber spectabile yielded a new dimeric flavonol glycoside for which the name kaempferol-3-O-(4″-O-acetyl)-α-L-rhamnopyranoside-(I-6,II-8)-kaempferol-3-O-(4″-O-acetyl)-α-L-rhamnopyranoside; spectaflavoside A (1) was proposed, along with kaempferol and its four acetylrhamnosides (2-6), demethoxycurcumin (7) and curcumin (8). The structure of spectaflavoside A was elucidated by spectroscopic methods including, 1D and 2D NMR techniques. This is the first report on the occurrence of a dimeric flavonol glycoside in the Zingiberaceae and the second in nature. Spectaflavoside A was found to be a potent iron chelating agent.     

Virulotyping of <Emphasis Type="Italic">Salmonella enterica</Emphasis> subsp. <Emphasis Type="Italic">enterica</Emphasis> isolated from indigenous vegetables and poultry meat in Malaysia using multiplex-PCR

The increased occurrence of Salmonella occurrence in local indigenous vegetables and poultry meat can be a potential health hazards. This study is aimed to detect the prevalence of twenty different virulence factors among Salmonella enterica strains isolated from poultry and local indigenous vegetables in Malaysia via an optimized, rapid and specific multiplex PCR assay. The assay encompasses a total of 19 Salmonella pathogenicity islands genes and a quorum sensing gene (sdiA) in three multiplex reaction sets. A total of 114 Salmonella enterica isolates belonging to 38 different serovars were tested. Each isolate in under this study was found to possess up to 70% of the virulence genes tested and exhibited variable pathogenicity gene patterns. Reproducibility of the multiplex PCR assay was found to be 100% and the detection limit of the optimized multiplex PCR was tested with lowest detectable concentration of DNA 0.8 pg μl⁻¹. This study demonstrated various Salmonella pathogenicity island virulence gene patterns even within the same serovar. This sets of multiplex PCR system provide a fast and reliable typing approach based on Salmonella pathogenicity islands, thus enabling an effective monitoring of emerging pathogenic Salmonella strains as an additional tool in Salmonella surveillance studies.     

Production of hepatitis B core antigen in a stirred tank bioreactor: The influence of temperature and agitation

The influence of temperature and agitation on the growth ofEscherichia coli expressing hepatitis B core antigen (HBcAg) in stirred tank bioreactor were investigated. The highest specific growth rate forE. coli (0.844 h⁻¹) was achieved at a temperature of 37°C and an agitation speed of 250 rpm. The activation energy for the growth of theE. coli strain W3110IQ in the stirred tank bioreactor was estimated to be 11 kcal/mol. The highest protein yield was achieved at a temperature of 44°C and an agitation speed of 250 rpm. The relative protein concentration at 44°C is 30 and 6% higher compared to that at 30 and 37°C, respectively.     

Heterogeneity of Light Availability and its Effects on Simulated Carbon Gain of Tree Leaves in a Small Gap and the Understory in a Tropical Rain Forest1

To clarify the small-scale heterogeneity of light regimes in a rain forest, photosynthetic photon flux density (PFD) was measured at 1-min intervals during six days at 12 microsites in each of two plots, a small gap and an understory in Pasoh Forest Reserve, Peninsular Malaysia. Frequency distribution of microsite PFD was unimodal with the peak value between 16 and 32 μmol/m²/sec in the small gap, but between 8 and 16 μmol/m²/sec in the understory. In the small gap, PFD was more variable among microsites; total daily PFD and daily sunfleck PFD exceeding 10 μmol/ m²/sec tended to be higher (P <0.05; t-test) compared to those in the understory. Sunfleck PFD exceeding 50 μmol/ m²/sec, however, showed no difference between the two plots. Diffuse PFD transmittance, defined as the ratio of PFD in the forest to that measured at 43 m above ground during the periods 0800-0810 and 1750-1800 h, was significantly higher in the small gap than in the understory plot. Diffuse PFD transmittance was also positively correlated with microsite total daily PFD. To examine the effects of the subtle heterogeneity of light regimes on leaf carbon gain, we simulated carbon gain by sun and shade leaves in a typical shade-tolerant species, Brosimum aticastrum Sw. (Moraceae). Despite the similarity in total daily PFD, total daily carbon gain was considerably higher in the gap than in the understory for both sun and shade leaves. This study suggests that frequency distribution of PFD is critical in describing microsite PFD regimes and determining leaf carbon gain in the tropical forest floor.     

Effect of temperature on stability of marker constituents in Echinacea purpurea root formulations.

Stability of an alkamide and a phenolic phytochemical marker in a hydro-alcoholic extract of Echinacea purpurea root and a dried powder prepared by evaporation of the extract was assessed in storage for 7 months at three temperature regimes: -20, 25 and 40 degrees Celsius. In the extract, the major alkamide, dodeca-2E, 4E, 8Z, 10E/Z-tetraenoic acid isobutyl amide, was not significantly affected by storage at any of the temperatures, but cichoric acid content declined as significantly (P = 0.05) at both 25 degrees C and 40 degrees C as compared to low-temperature storage. In the powder, the major alkamide showed a significantly reduced level at 25 degrees C and 40 degrees C while cichoric acid did not decline significantly. These results suggest that more attention should be given to the effect of formulation and temperature on storage of Echinacea products.     

Conformational analysis of rhazinilam and three-dimensional quantitative structure-activity relationships of rhazinilam analogues

3D QSAR of rhazinilam (1), an alkaloid isolated from Rhazya stricta (Apocynaceae) with an activity involving disassembly of microtubules and its derivatives was investigated by using the comparative molecular field analysis (CoMFA). In an effort to get a better understanding of the correlation between conformation and antitubulin activity of 1, most probable minimum energy conformation in solution of 1 was analyzed on the basis of NMR data of 1 in solution. The results indicated a correlation between the antitubulin activity of these alkaloids and the steric and electrostatic factors, which modulate their biological activity, and accounted for the potent activities of 1 with suitable relationship for the overall conformation.     

Sesquiterpenes and alkaloids from Scorodocarpus borneensis

A new sesquiterpene, scodopin, and a mixture of three tryptamine-type alkaloids, scorodocarpines A-C, were isolated from the fruits of Scorodocarpus borneensis, together with a known hemisynthetic sesquiterpene, cadalene-beta-carboxylic acid, which was isolated from the bark. The structures of the new compounds were elucidated by interpretation of spectral data, especially tandem mass spectrometry for the alkaloid mixture.     

Direct discrimination of different plant populations and study on temperature effects by Fourier transform infrared spectroscopy

Fourier transform infrared spectroscopy was used to characterise highland and lowland populations of Polygonum minus Huds. grown in different controlled environments. A thermal perturbation technique of two-dimensional correlation infrared spectroscopy (2D-IR) correlation spectra was applied to establish differences between the populations. The absorption peaks at 3,480 cm^?1 (hydroxyl group), 2,927 cm^?1 (methyl group), 1,623 cm^?1 (carbonyl group), and 1,068 cm^?1 (C–O group) were particularly powerful in separating the populations. These peaks, which indicate the presence of carbohydrate, terpenes, amide and flavonoids were more intense for the highland populations than lowland populations, and increased in environments with a higher temperature. Wavenumbers (1,634, 669 cm^?1) and (1,634, 1,555 cm^?1) in the 2D-IR correlation spectra provided fingerprint signals to differentiate plants grown at different temperatures. This study demonstrates that IR fingerprinting, which combines mid-IR spectra and 2D-IR correlation spectra, can directly discriminate different populations of P. minus and the effects of temperature.     

Synthesis and cytotoxic activity of organotin(IV) diallyldithiocarbamate compounds as anticancer agent towards colon adenocarcinoma cells (HT-29)

ContextDiphenyltin(IV) diallyldithiocarbamate compound (Compound 1) and triphenyltin(IV) diallyldithiocarbamate compound (Compound 2) are two newly synthesised compounds of organotin(IV) with diallyldithiocarbamate ligands.ObjectiveTo assess the cytotoxic effects of two synthesised compounds against HT-29 human colon adenocarcinoma cells and human CCD-18Co normal colon cells.Materials and methodsTwo successfully synthesised compounds were characterised using elemental (carbon, hydrogen, nitrogen, and sulphur) analysis, Fourier-Transform Infrared (FTIR), and ¹H, ¹³C ¹¹⁹Sn Nucleus Magnetic Resonance (NMR) spectroscopies. The single-crystal structure of both compounds was determined by X-ray single-crystal analysis. The cytotoxicity of the compounds was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazholium bromide (MTT) assay upon 24 h of treatment. While the mode of cell death was determined based on the externalisation of phosphatidylserine using a flow cytometer.ResultsThe elemental analysis data of the two compounds showed an agreement with the suggested formula of (C₆H₅)₂Sn[S₂CN(C₃H₅)₂]₂ for Compound 1 and (C₆H₅)₃Sn[S₂CN(C₃H₅)₂] for Compound 2. The two major peaks of infrared absorbance, i.e., ν(C = N) and ν(C = S) were detected at the range of 1475–1479 cm⁻¹ and 972–977 cm⁻¹, respectively. The chemical shift of carbon in NCS₂ group for Compound 1 and 2 were found at 200.82 and 197.79 ppm. The crystal structure of Compound 1 showed that it is six coordinated and crystallised in monoclinic, P2₁/c space group. While the crystal structure of Compound 2 is five coordinated and crystallised in monoclinic, P2₁/c space group. The cytotoxicity (IC₅₀) of the two compounds against HT-29 cell were 2.36 μM and 0.39 μM. Meanwhile, the percentage of cell death modes between 60% and 75% for compound 1 and compound 2 were mainly due to apoptosis, suggesting that both compounds induced growth arrest.ConclusionOur study concluded that the synthesised compounds showed potent cytotoxicity towards HT-29 cell, with the triphenyltin(IV) compound showing the highest effect compared to diphenyltin(IV).     

<Emphasis Type="Italic">In vitro</Emphasis> conservation of Malaysian biodiversity—achievements,challenges and future directions

Malaysia is fortunate and proud to contain some of the world’s richest biodiversity. In Malaysia, there are an estimated 185,000 species of fauna and 12,500 species of flowering plants, many of which are endemic to tropical forests in this region. Indeed, such diversity is an important and invaluable national asset to safeguard both present and future generations. In vitro conservation offers possible techniques for the preservation of plant germplasm that at present is difficult to maintain or is maintained with limited success. Research at the Universiti Kebangsaan Malaysia (The National University of Malaysia) focuses on the cryopreservation of woody fruit species with seeds that cannot tolerate cryopreservation (recalcitrant or intermediate). Among the plants with recalcitrant seeds are such traditionally important edible tropical fruits as mangosteen, langsat, and rambai (Garcinia mangostana, Lansium domesticum, and Baccaurea motleyana). Citrus aurantifolia, Citrus suhuiensis, Citrus madurensis, Citrus hystrix, and Fortunella polyandra are among the Citrus and Citrus-related species studied. Cryopreservation studies include the Nepenthes species (pitcher plants) of Malaysia. Fundamental research on desiccation and low-temperature tolerance and on the physiology of desiccation are used to understand seed behavior, a prerequisite for the development of successful conservation techniques. At the same time, cryopreservation protocols for several Citrus and forestry species were developed for embryonic axes and adventitious shoots, mainly using rapid dehydration and PVS2 vitrification techniques. There are no successful standard techniques or protocols for species with highly recalcitrant seeds such as Garcinia species. Modification of existing protocols or development of new methods is required, but this can be accomplished only when a detailed understanding of the recalcitrant nature of the seeds or explants is achieved. While we have considerable knowledge concerning the basics of biochemical processes and some molecular data from work on desiccation-tolerant seeds, a great need remains for understanding the cause of the recalcitrance or desiccation sensitivity of these seeds. It may be necessary to use a systems biology approach that exploits the “omics” technologies to generate global molecular data. In combination with bioinformatics for data integration and analyses, this approach would move toward improved modeling of the biological pathways associated with the development of recalcitrant seeds.