Cordylactam,a new alkaloid from the spider pathogenic fungus Cordyceps sp. BCC 12671

Cordylactam (1), a new lactam-fused 4-pyrone was isolated from the spider pathogenic fungus Cordyceps sp. BCC 12671. The structure was elucidated on the basis of NMR spectroscopic and mass spectrometry data, which was further confirmed by the spectroscopic analyses of a semisynthetic derivative. This is the first report of a new compound from spider pathogenic Cordyceps species.     

Synthethic peptide used to develop antibodies for detection of polyhedrin from monodon baculovirus (MBV)

The use of previously published primers to amplify the monodon baculovirus (MBV) polyhedrin gene sequence by polymerase chain reaction (PCR) from post larvae (PL) of Thai Penaeus monodon resulted in failure. As a result, the putative polyhedrin protein of MBV was isolated from infected PL by homogenization, differential centrifugation and density gradient centrifugation with verification by transmission electron microscopy (TEM). By SDS-PAGE, a single major protein band at 58 kDa was obtained from the putative polyhedrin fraction and this corresponded to a previous report of the molecular weight of polyhedrin from MBV. When used for N-terminal sequence analysis, the putative polyhedrin protein yielded a sequence of 25 amino acids (M F D D S M M M E N M D D L S G D Q K M V L T L A) that did not correspond to the deduced amino acid sequence derived from a previous report of a putative MBV polyhedrin gene amplicon. Despite this, a synthetic peptide of our 25 amino acid sequence (25Pmbv) was conjugated with bovine serum albumin and used as an antigen for antiserum production in mice. Using immunohistochemistry with tissue sections of PL infected with MBV or other viruses, the mouse anti-25Pmbv antiserum showed strong immunoreactivity to occlusion bodies of MBV only. It also showed strong reactivity to the 58 kDa putative polyhedrin protein in Western blots. Altogether, the results suggest that the 58 kDa protein is Thai MBV polyhedrin and that a previously reported MBV polyhedrin gene sequence may represent another protein or polyhedrin from a different variety of MBV.     

Purification and characterization of a Bacillus circulans No. 4.1 chitinase expressed in Escherichia coli

Summary A DNA fragment encoding for 598 amino acids of chitinase protein from Bacillus circulans No. 4.1 was subcloned into pQE-30 expression vector and transformed into Escherichia coli M15 (pREP4). The molecular weight of the expressed protein was approximately 66 kDa. Enzymatic activity of the recombinant protein was assayed after purification using affinity chromatography on a nickel chelating resin. The enzyme hydrolyzed N-acetylchitooligosaccharides mainly to N-acetylchitobiose, and was active toward chitin, carboxymethyl-chitin, colloidal chitin, glycol chitin and 4-methylumbelliferyl-β-d-N, N′-diacetylchitobiose. The pH and temperature optima of the chitinase enzyme were 7.0 and 45 °C, respectively. This enzyme was stable in the pH range of 5.0–9.0 and at temperatures up to 50 °C. In addition, when cleaved by a proteolytic enzyme, the 20-kDa product could retain high chitinolytic activity.     

A curcumin-diglutaric acid conjugated prodrug with improved water solubility and antinociceptive properties compared to curcumin

In this work, a curcumin-diglutaric acid (CurDG) prodrug was synthesized by conjugation of curcumin with glutaric acid via an ester linkage. The water solubility, partition coefficient, release characteristics, and antinociceptive activity of CurDG were compared to those of curcumin. The aqueous solubility of CurDG (7.48 μg/mL) is significantly greater than that of curcumin (0.068 μg/mL). A study in human plasma showed that the CurDG completely releases curcumin within 2 h, suggesting the ability of CurDG to serve as a prodrug of curcumin. A hot plate test in mice showed the highest antinociceptive effect dose of curcumin at 200 mg/kg p.o., whereas CurDG showed the same effect at an effective dose of 100 mg/kg p.o., indicating that CurDG significantly enhanced the antinociceptive effect compared to curcumin. The enhanced antinociceptive effect of CurDG may be due to improved water solubility and increased oral bioavailability compared to curcumin.     

Loop‐mediated isothermal amplification assay targeting the blaCTX‐M9 gene for detection of extended spectrum β‐lactamase‐producing Escherichia coli and Klebsiella pneumoniae

Extended‐spectrum β‐lactamases (ESBLs) produced by Enterobacteriaceae are one of the resistance mechanisms to most β‐lactam antibiotics. ESBLs are currently a major problem in both hospitals and community settings worldwide. Rapid and reliable means of detecting ESBL‐producing bacteria is necessary for identification, prevention and treatment. Loop‐mediated isothermal amplification (LAMP) is a technique that rapidly amplifies DNA with high specificity and sensitivity under isothermal conditions. This study was aimed to develop a convenient, accurate and inexpensive method for detecting ESBL‐producing bacteria by a LAMP technique. ESBLs‐producing Escherichia coli and Klebsiella pneumoniae were isolated from a tertiary hospital in Bangkok, Thailand and reconfirmed by double‐disk synergy test. A set of four specific oligonucleotide primers of LAMP for detection of bla_CTX‐M9 gene was designed based on bla_CTX‐M9 from E. coli (GenBank Accession No. AJ416345). The LAMP reaction was amplified under isothermal temperature at 63°C for 60 min. Ladder‐like patterns of band sizes from 226 bp of the bla_CTX‐M9 DNA target was observed. The LAMP product was further analyzed by restriction digestion with MboI and TaqI endonucleases. The fragments generated were approximately 168, 177 and 250 bp in size for MboI digestion and 165, 193, 229, 281 and 314 bp for TaqI digestion, which is in agreement with the predicted sizes. The sensitivity of the LAMP technique to bla_CTX‐M9 was greater than that of the PCR method by at least 10,000‐fold. These results showed that the LAMP primers specifically amplified only the bla_CTX‐M9 gene. Moreover, the presence of LAMP amplicon was simply determined by adding SYBR Green I in the reaction. In conclusion, this technique for detection of ESBLs is convenient, reliable and easy to perform routinely in hospitals or laboratory units in developing countries.     

Formulation,Physicochemical Characterization,and In Vitro Study of Chitosan/HPMC Blends-Based Herbal Blended Patches

The current work prepared chitosan/hydroxypropyl methylcellulose (HPMC) blends and studied the possibility of chitosan/HPMC blended patches for Zingiber cassumunar Roxb. The blended patches without/with crude Z. cassumunar oil were prepared by homogeneously mixing the 3.5% w/v of chitosan solution and 20% w/v of HPMC solution, and glycerine was used as plasticizer. Then, they were poured into Petri dish and produced the blended patches in hot air oven at 70 ± 2°C. The blended patches were tested and evaluated by the physicochemical properties: moisture uptake, swelling ratio, erosion, porosity, Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction, and photographed the surface and cross-section morphology under SEM technique. Herbal blended patches were studied by the in vitro release and skin permeation of active compound D. The blended patches could absorb the moisture and became hydrated patches that occurred during the swelling of blended patches. They were eroded and increased by the number of porous channels to pass through out for active compound D. In addition, the blended patches indicated the compatibility of the blended ingredients and homogeneous smooth and compact. The blended patches made from chitosan/HPMC blends provide a controlled release and skin permeation behavior of compound D. Thus, the blended patches could be suitably used for herbal medicine application.KEY WORDS: chitosan, formulation, herbal blended patches, HPMC, Zingiber cassumunar Roxb     

Purification and Characterization of Chitinase from Bacillus circulans No.4.1

Bacillus circulans No.4.1 produced a high level of chitinase when cells were grown in tryptic soy broth supplemented with 0.3% colloidal chitin at 35°C for 5 days. Purification was carried out by protein precipitation with 80% saturation ammonium sulfate, anion-exchange chromatography with DEAE-Sephacel, and gel filtration with Sephadex G-100, sequentially. The purified enzyme could be demonstrated as a single band on SDS-PAGE, estimated to be 45 kDa. This enzyme could hydrolyze colloidal chitin, purified chitin, glycol chitin, carboxymethyl-chitin (CM-chitin), and 4-methylumbelliferyl-β-D-N,N′-diacetylchitobioside [4-MU-(GlcNAc)₂]. The optimal conditions for this chitinase were pH 8.0 and 40°C. The isoelectric point of the chitinase was 5.1. The amino acid composition of the purified chitinase was determined. The initial 20 amino acid residues of the N-terminal were found to be alanine (A), proline (P), tryptophan (W), asparagine (N), serine (S), lysine (K), glycine (G), asparagine (N), tyrosine (Y), alanine (A), leucine (L), proline (P), tyrosine (Y), tyrosine (Y), arginine (R), glycine (G), alanine (A), tryptophan (W), alanine (A), and valine (V). Knowledge of these properties of chitinase from B. circulans No. 4.1 should be useful in the development of genetically engineered Bacillus sp. as biopesticides. Received: 19 March 1999 / Accepted: 30 April 1999     

Expression of chitinase-encoding genes in Bacillus thuringiensis and toxicity of engineered B. thuringiensis subsp. aizawai toward Lymantria dispar larvae

Chitinase genes from Aeromonas hydrophila and Bacillus circulans No.4.1 were cloned into the plasmid pHY300PLK and designated as pHYA2 and pHYB43, respectively. Both plasmids were introduced into various strains of B. thuringiensis by electroporation. Plasmid pHYB43 was generally structurally stable, but showed lower segregrational stability than pHYA2 in B. thuringiensis subsp. aizawai when grown under nonselective conditions. The production of chitinase from B. thuringiensis subsp. aizawai harboring pHYB43 or pHYA2 could be detected after native polyacrylamide gel electrophoresis by using 4-methylumbelliferyl -D-N,N- diacetylchitobioside as the substrate. Moreover, B. thuringiensis subsp. aizawai harboring pHYB43 gave 15 times higher chitinase activity than when harboring pHYA2, as determined by means of a colorimetric method using glycol chitin as the substrate. In addition, B. thuringiensis subsp. aizawai harboring pHYB43 was more toxic to gypsy moth larvae (Lymantria dispar) than parental B. thuringiensis subsp. aizawai or its clone harboring pHYA2.     

Genotypic analysis of Nomuraea rileyi collected from various noctuid hosts

The genetic diversity of 79 Nomuraea rileyi isolates from various lepidopteran hosts in Asia, North America, and South America was evaluated using amplified fragment length polymorphism (AFLP) analysis. Cluster analysis separated the N. rileyi isolates into two major groups and seven subgroups. The resulting dendrogram generally classified the N. rileyi isolates based on insect host and geographical region. The haplotypic diversity index of N. rileyi subpopulations from each location and host origin was ranging from 0.8788 to 1.000. However, analysis of molecular variance (AMOVA) demonstrated no significant differences (p =0.3421) among N. rileyi isolates from different continents. Whereas the genetic variation among the N. rileyi populations from the different host insects within each continent was significantly different (p <0.0001).