Wan Ahmad Yaacob

Synthesis, antibacterial activity and cytotoxicity of new fused pyrazolo (1,5-a)pyrimidine and pyrazolo(5,1-c)(1,2,4)triazine derivatives from new 5-aminopyrazoles

New 5-aminopyrazoles 2a-c were prepared in high yields from the reaction of known α,α-dicyanoketene-N,S-acetals 1a-c with hydrazine hydrate under reflux in ethanol. These compounds were utilized as intermediates to synthesize pyrazolo[1,5-a]-pyrimidines 3a-c, 4a-d, 5a-c, and 6a-c, as well as pyrazolo[5,1-c][1,2,4]triazines 7a-c and 8a-c, by the reaction of 2-[bis(methylthio)methylene]malononitrile, α,α-dicyanoketene-N,S-acetals 1a-b, acetylacetone, acetoacetanilide as well as acetylacetone, and malononitrile, respectively. Furthermore, cyclization of 2a-c with pentan-2,5-dione yielded the corresponding 5-pyrrolylpyrazoles 9a-c. Moreover, fusion of 2a-c with acetic anhydride resulted in the corresponding 1-acetyl-1H-pyrazoles 10a-c. The antibacterial activity and cytotoxicity against Vero cells of several selected compounds are also reported.

Purification and characterisation of antibacterial peptide-containing compound derived from palm kernel cake

Palm kernel cake (PKC), the most useful by-product resulted from palm kernel oil production. In this study, PKC-derived protein product was found suitable for use as an antimicrobial agent with potent antibacterial activity, particularly against Bacillus species, after enzymatic hydrolysis with alcalase. The hydrolysate was further purified by gel filtration chromatography. The purified fraction was found to have 14.63±0.70% (w/w) protein, a molecular mass of 2.4kDa and low hemolytic activity (<50% hemolysis of human erythrocytes at concentration of 1000μg/ml). The presence of lysine and the major component lauric acid derivative, as indicated by electrospray ionisation-mass spectrometry (ESI-MS) direct infusion and nuclear magnetic resonance (NMR) spectroscopy, may have contributed to the antibacterial effect of purified PKC fraction. This study suggests that the antibacterial PKC compound may be not a pure peptide but instead a peptide-containing compound high in lauric acid derivative.

Acuminatol and Other Antioxidative Resveratrol Oligomers from the Stem Bark of Shorea acuminata

A new resveratrol dimer, acuminatol (1), was isolated along with five known compounds from the acetone extract of the stem bark of Shorea acuminata. Their structures and stereochemistry were determined by spectroscopic methods, which included the extensive use of 2D NMR techniques. All isolated compounds were evaluated for their antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (RSA) and the β-carotene-linoleic acid (BCLA) assays, and compared with those of the standards of ascorbic acid (AscA) and butylated hydroxytoluene (BHT). All compounds tested exhibited good to moderate antioxidant activity in the DPPH assay (IC50s 0.84 to 10.06 mM) and displayed strong inhibition of β-carotene oxidation (IC50s 0.10 to 0.22 mM). The isolated compounds were evaluated on the Vero cell line and were found to be non-cytotoxic with LC50 values between 161 to 830 µM.

Development of Nano-Zero Valent Iron for the Remediation of Contaminated Water

Various materials are currently available to remove heavy metals from groundwater such as activated carbons, carbon nano tubes, bentonite and Zero Valent Iron (ZVI). All these materials are capable to transform toxic substances to non toxic and/or to adsorb toxic substances via ionic exchange, ion precipitation and adsorption. Nano-sized Zero Valent Iron (NZVI) is considered as an effective adsorbent and ideal technology for in-situ remediation of heavy metal contaminated groundwater. Therefore, this study was conducted to produce NZVI via chemical reduction process using FeCl2•4H2O titrated with reduction agent of NaBH4. The process is divided into four stages; mixing, separating, washing and drying. The materials produced from these processes are varies in colours, i.e. black, dark brown, brown and light brown. Colour variation observed is due to the intensity of oxidation process of these materials and became the main predicament of this research, especially during drying stage. Samples produced were marked according to their colours. The particle size of selected Zero Valent Iron samples namely ZVI-1b, ZVI-3b and ZVI-4b were determined using Mastersizer instrument. Sample ZVI-3b has a particle size ranging from 0.4 μm – 1000 μm and it is mainly dominated by 50 μm particles. ZVI-4b has the same size range as ZVI-3b but it is dominated mainly by particles of 60 μm. Meanwhile, the particle size for ZVI-1a could not be detected because of much smaller size which is well below the detection range of the size analyser. Another four samples namely ZVI-1a, ZVI-1b, ZVI-2b and ZVI-3b were analysed using Scanning Electron Microscopy (SEM). The results show that ZVI-1a has a platy texture, ZVI-1b has a dendritic texture and ZVI-2b has both platy and dendritic textures. While ZVI-3b shows a botryoidal texture. All results including colour, particle size and SEM images indicate that there is a potential of producing Nano-Zero Valent Iron especially ZVI-1b that has properties (size and micro texture) similar to Nano-Zero Valent Iron. Batch tests further confirmed the capability of ZVI-1b to effectively remove Cu from contaminated solution for up to 97 %.

Synthesis of Some Novel α-Cyanoketene-N,S-acetals Derived from Secondary Aliphatic Amines and Their Use in Pyrazole Synthesis

Abstract New α-cyanoketene-N,S-acetals 2(a–g) and β-dialkylamine-α-cyanoacrylates 3(g–i) were synthesized in good to excellent yields by the reaction of ethyl 2-cyano-3,3-bis(methylthio)acrylate 1 with secondary aliphatic amines (i.e., N-methylalkyl- and N-ethylalkylamines), and pyrrolidine, in the presence of triethylamine, under reflux in ethanol, for 1–16 h, depending on the amine used. Five N-methylalkyl amines and pyrrolidine yielded exclusively mono-substituted N,S-acetals 2(a–f) in good yields. On the other hand, N-ethylbenzylamine gave a mixture of monosubstituted products including N,S-acetal 2g in 35% yield and the unexpected product ethyl 3-[benzyl(ethyl)amino]-2-cyanoacrylate 3g in 50% yield. N-Ethylcyclohexylamine and N-ethylbutylamine did not produce N,S-acetals and gave only the unexpected products ethyl 2-cyano-3-[cyclohexyl(ethyl)amino]acrylate 3h and ethyl 3-[butyl(ethyl)amino]-2-cyanoacrylate 3i in good yields. The α-cyanoketene-N,S-acetals 2(a–f), 2j, and 2k underwent cyclization with the binucleophile hydrazine in ethanol under reflux to afford substituted pyrazoles 4(a–f), 4j, and 4k in good yields. [Supplementary materials are available for this article. Go to the publishers online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.] GRAPHICAL ABSTRACT

Essential Oil Composition of Three Air-Dried Parts of Etlingera brevilabrum

Essential oil from the air-dried rhizomes, stems and leaves of Etlingera brevilabrum were hydrodistilled using a Clevenger-type apparatus and identified by GC and GC-MS. Monoterpene hydrocarbons dominated the oils from the stems and leaves (66.8 and 89.8 % respectively) whereas oxygenated monoterpenes were dominant in the rhizomes (40.2 %). Eucalyptol (27.6 %), β-pinene (13.4 %), caryophyllene oxide (10.5 %) and α-thujene (10.1 %) were the major compounds in the rhizomes oil; limonene (28.6 %), β-pinene (21.6 %), α-thujene (13.9 %) and caryophyllene oxide (4.6 %) in the stems; and β-pinene (52.6 %), α-thujene (28.6 %) and o-cymene (7.8 %) in the leaves.

Physicochemical Properties of Starch from Dioscorea pyrifolia tubers

Starch from Dioscorea pyrifolia tubers was characterized for its proximate composition, physicochemical properties and toxicity. This starch contains 44.47±1.86% amylose, 4.84±0.29% moisture, 0.88±0.21% ash, 1.34±0.11% proteins and 92.73±0.48% carbohydrates. X-ray diffraction (XRD) analysis showed a type-C starch with a relative crystallinity of 23.31±2.41%. The starch granules are polyhedral, with a diameter of 2.8 to 5.6μm and average size of 3.93±1.47μm. Initial, peak and finishing gelatinization temperatures for the starch were 71.51±0.07, 75.05±0.15, and 78.25±0.18°C, respectively; the gelatinization enthalpy was 3.86±0.02J/g, and the peak height index was 1.09±0.05. Thermogravimetric analysis showed a weight loss of 85.81±0.52% and a decomposition temperature of 320.16±0.35°C, which indicated that there was good thermal stability of the starch. Fish embryo toxicity (FET) showed that the starch was not toxic and that it was suitable for food and non-food industries.

Immunomodulatory effects of 1-(6-hydroxy-2-isopropenyl-1-benzofuran-5-yl)-1-ethanone from Petasites hybridus and its synthesized benzoxazepine derivatives.

Abstract1-(6-Hydroxy-2-isopropenyl-1-benzofuran-5-yl)-1-ethanone (1), isolated from the roots of Petasites hybridus L., and a series of synthetic benzoxazepine derivatives of compound 1 (2–6) were evaluated for their immunomodulatory effects. The compounds were evaluated for their effects on the respiratory burst of human whole blood and isolated human polymorphonuclear leukocytes (PMNs) using luminol- and lucigenin-based chemiluminescence (CL) assays, and their effect on chemotactic migration of PMNs was assessed using the Boyden chamber technique. Compound 1 exhibited stronger inhibition than acetylsalicylic acid (ASA) on luminol-enhanced CL of PMNs. It also inhibited PMN chemotaxis with an IC50 value comparable to that of ibuprofen. Of the compounds tested, 5 was the most effective in inhibiting luminol-enhanced CL and also strongly inhibited lucigenin-enhanced CL with IC50 values lower than that of ASA. Compound 2 was the most active in inhibiting migration of PMNs and was five times stronger than ibuprofen. The results suggest that compound 1 and its synthesized benzoxazepine derivatives, especially compounds 2 and 5, were able to modulate the innate immune response of phagocytes at different steps, emphasizing their potential as leads for the development of new immunomodulatory agents.

Volatile Oil Compositions of Several Parts of Etlingera fulgens from Malaysia

Abstract Volatile oils obtained by hydrodistillation of the fresh leaves, leafy shoots, rhizomes, flowers, peduncles and whole plant (leaves, leafy shoots and rhizomes) of Etlingera fulgens were analyzed by gas chromatography with flame ionization detector (GC-FID) and gas chromatography/mass spectrometry (GC-MS). Fifty five compounds were identified. Some of these components are common in two or more plant parts. The fresh leaf, leafy shoot, rhizome, whole plant, flower, and peduncle oils of E. fulgens comprised terpenes (5.03–24.49 %) and non-terpenic components (65.84–90.46 %). The terpenes include monoterpenes (1.92– 3.22 %), oxygenated monoterpenes (0.87–17.71 %), sesquiterpenes (0–10.05 %), oxygenated sesquiterpenes (0–0.84 %) and oxygenated diterpens (0–0.85 %), while non-terpenic compounds consist of hydrocarbons (31.21–52.26 %), aldehydes (0–10.49 %), ketones (1.29–5.86 %), alcohols (8.22–15.4 9%), esters (19.13–30.68 %) and non-terpenic carboxylic acids (0–7.04 %). In the oils of E. fulgens, non-terpenic compounds were identified as major constituents.

Transcriptome analysis of methicillin-resistant Staphylococcus aureus in response to stigmasterol and lupeol

OBJECTIVES Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen with multiple antibiotic resistance that causes morbidity and mortality worldwide. Multidrug-resistant (MDR) MRSA with increased resistance to currently available antibiotics has challenged the world to develop new therapeutic agents. Stigmasterol and lupeol, from the plant Phyllanthus columnaris, exhibit antibacterial activities against MRSA. The aim of this study was to utilise next-generation sequencing (NGS) to provide further insight into the novel transcriptional response of MRSA exposed to stigmasterol and lupeol. METHODS Time-kill analysis of one MRSA reference strain (ATCC 43300) and three clinical isolates (WM3, BM1 and KJ7) for both compounds was first performed to provide the bacteriostatic/bactericidal profile. Then, MRSA ATCC 43300 strain treated with both compounds was interrogated by NGS. RESULTS Both stigmasterol and lupeol possessed bacteriostatic properties against all MRSA tested; however, lupeol exhibited both bacteriostatic and bactericidal properties within the same minimum inhibitory concentration and minimum bactericidal concentration values against BM1 (12.5mg/mL). Transcriptome profiling of MRSA ATCC 43300 revealed significant modulation of gene expression with multiple desirable targets by both compounds, which caused a reduction in the translation processes leading to inhibition of protein synthesis and prevention of bacterial growth. CONCLUSIONS This study highlights the potential of both stigmasterol and lupeol as new promising anti-MRSA agents.