The Comparative Studies of Binding Activity of Curcumin and Didemethylated Curcumin with Selenite: Hydrogen Bonding vs Acid-Base Interactions.

In this report, the in vitro relative capabilities of curcumin (CCM) and didemethylated curcumin (DCCM) in preventing the selenite-induced crystallin aggregation were investigated by turbidity tests and isothermal titration calorimetry (ITC). DCCM showed better activity than CCM. The conformers of CCM/SeO3(2-) and DCCM/SeO3(2-) complexes were optimized by molecular orbital calculations. Results reveal that the selenite anion surrounded by CCM through the H-bonding between CCM and selenite, which is also observed via IR and NMR studied. For DCCM, the primary driving force is the formation of an acid-base adduct with selenite showing that the phenolic OH group of DCCM was responsible for forming major conformer of DCCM. The formation mechanisms of selenite complexes with CCM or DCCM explain why DCCM has greater activity than CCM in extenuating the toxicity of selenite as to prevent selenite-induced lens protein aggregation.

Characterization of the flocculating agent from the spontaneously flocculating microalga Chlorella vulgaris JSC-7.

High cost of biomass recovery is one of the bottlenecks for developing cost-effective processes with microalgae, particularly for the production of biofuels and bio-based chemicals through biorefinery, and microalgal biomass recovery through cell flocculation is a promising strategy. Some microalgae are naturally flocculated whose cells can be harvested by simple sedimentation. However, studies on the flocculating agents synthesized by microalgae cells are still very limited. In this work, the cell flocculation of a spontaneously flocculating microalga Chlorella vulgaris JSC-7 was studied, and the flocculating agent was identified to be cell wall polysaccharides whose crude extract supplemented at low dosage of 0.5 mg/L initiated the more than 80% flocculating rate of freely suspended microalgae C. vulgaris CNW11 and Scenedesmus obliquus FSP. Fourier transform infrared (FTIR) analysis revealed a characteristic absorption band at 1238 cm(-1), which might arise from PO asymmetric stretching vibration of [Formula: see text] phosphodiester. The unique cell wall-associated polysaccharide with molecular weight of 9.86×10(3) g/mol, and the monomers consist of glucose, mannose and galactose with a molecular ratio of 5:5:2. This is the first time to our knowledge that the flocculating agent from C. vulgaris has been characterized, which could provide basis for understanding the cell flocculation of microalgae and breeding of novel flocculating microalgae for cost-effective biomass harvest.

Characterization of flocculating agent from the self-flocculating microalga Scenedesmus obliquus AS-6-1 for efficient biomass harvest.

In the present work, the extracellular biopolymers from the self-flocculating microalga Scenedesmus obliquus AS-6-1 were studied. It was revealed that the self-flocculation of the microalgal cells was mediated by cell wall-associated polysaccharides with a molecular weight of 127.9 kDa. Sugar compositions analysis indicated that the monomers consist of glucose, mannose, galatose, rhamnose and fructose with the molar ratio of 8:5:3:2:1. Addition of 0.6 mg/L purified flocculating agent resulted in the fast flocculation of freely suspended cells of S. obliquus and Chlorella vulgaris. The flocculating activity is stable between pH 6 and 8 and at 20-60°C.

Oligosaccharide and peptidoglycan of Ganoderma lucidum activate the immune response in human mononuclear cells.

The acid-hydrolyzed fragments of Ganoderma lucidum polysaccharides (GLPS) obtained by Smith degradation were separated by size-exclusion chromatography into two major water-soluble fractions: peptidoglycans (GLPS-SF1) and oligosaccharides (GLPS-SF2). Both fractions induced CD69 in human peripheral blood mononuclear cells (hPB-MNCs), and they displayed distinct immunomodulating properties. GLPS-SF1, with a molecular weight of around 20 kDa, were heterogeneous peptidoglycans composed of glucose/mannose (4:1) that exhibited biological activities with Th1 cytokines IL-12, IL-2, TNF-α, and IFN-γ in hPB-MNCs and stimulated macrophage cytokine expression via Toll-like receptor 4 (TLR4) signaling. For GLPS-SF2, with a molecular weight of around several kilodaltons, its sugar sequence was elucidated by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy as [-α-1,4-Glc-(ß-1,4-GlcA)(3)-](n). This oligosaccharide displayed specific immune property with low monocyte induction, greatly stimulated cell activation and proliferation of NK and T cells. This oligosaccharide isolated from G. lucidum polysaccharides with internal glucuronic acids/glucose repeat unit in a 3:1 ratio may be responsible for the active stimulation of NK and T cells.

Anti-UVC irradiation and metal chelation properties of 6-benzoyl-5,7-dihydroxy-4-phenyl-chromen-2-one: an implications for anti-cataract agent.

Coumarin derivative 1, 5,7-dihydroxy-6-(3-methyl-1-butyryl)-4-phenyl-chromen- 2-one, has been reported to possess radical scavenging activity and DNA protection. We have synthesized a series of coumarins with structural modifications at positions C4, C5, C6 and C7 and evaluated them for their anti-UVC properties. Coumarin 7, 6-benzoyl-5,6-dihydroxy-4-phenyl-chromen-2-one, was found to have the most potent activity in protecting porcine γ-crystallin against UVC insults. Results of fluorescence assays indicated that compound 7 was capable of decreasing the loss of intensity while lens crystallins and DNA PUC19 were irradiated with UVC. Presence of compound 7 decreased hydroxyl radical levels determined by probe 1b and the free iron concentrations determined by Ferrozine reagent. The chelation assay showed that compound 7 was chelated to metal via 6-CO and 5-OH on the benzopyrone ring. The observed protective effects of compound 7 towards crystallins from insults of UVC and free radicals may be due to its iron-chelating activity and its peak absorption at 254 nm.

Proteomannans in biofilm of Helicobacter pylori ATCC 43504.

BACKGROUND: The human bacterial pathogen Helicobacter pylori forms biofilms. However, the constituents of the biofilm have not been extensively investigated. In this study, we analyzed the carbohydrate and protein components of biofilm formed by H. pylori strain ATCC 43504 (NCTC 11637). MATERIALS AND METHODS: Development of H. pylori biofilm was analyzed using scanning electron microscopy (SEM) and quantified using crystal violet staining. The extracted extracellular polysaccharide (EPS) matrix was analyzed using GC-MS and nuclear magnetic resonance (NMR) analyses. Proteomic profiles of biofilms were examined by SDS-PAGE while deletion mutants of upregulated biofilm proteins were constructed and characterized. RESULTS: Formation of H. pylori biofilm is time dependent as shown by crystal violet staining assay and SEM. NMR reveals the prevalence of 1,4-mannosyl linkages in both developing and mature biofilms. Proteomic analysis of the biofilm indicates the upregulation of neutrophil-activating protein A (NapA) and several stress-induced proteins. Interestingly, the isogenic mutant napA revealed a different biofilm phenotype that showed reduced aggregated colonial structure when compared to the wild type. CONCLUSIONS: This in vitro study shows that mannose-related proteoglycans (proteomannans) are involved in the process of H. pylori biofilm formation while the presence of upregulated NapA in the biofilm implies the potency to increase adhesiveness of H. pylori biofilm. Being a complex matrix of proteins and carbohydrates, which are probably interdependent, the H. pylori biofilm could possibly offer a protective haven for the survival of this gastric bacterial pathogen in the extragastric environments.

Structural variation of glycolipids from Meiothermus taiwanensis ATCC BAA-400 under different growth temperatures.

A major glycolipid, alpha-Galf(1-3)-alpha-Galp(1-6)-beta-GlcpNAcyl(1-2)-alpha-Glcp(1-1)-2-acylalkyldiol, is obtained from Meiothermus taiwanensis. This novel glycolipid is found only when the bacterium grows above 62 degrees C, which is significantly different from those from the same bacteria incubated at 55 degrees C. Terminal galactofuranoside and 1,2-alkyldiol lipids replaced galactopyranoside and glycerol lipids, respectively, under increased growth temperature. This variation is likely necessary for bacteria for keeping the stable outer membrane and surviving under extreme environments.

Discovery of new natural products by intact-cell mass spectrometry and LC-SPE-NMR: malbranpyrroles, novel polyketides from thermophilic fungus Malbranchea sulfurea.

Six photosensitive polyketides, malbranpyrroles A-F, were discovered from the thermophilic fungus Malbranchea sulfurea by using intact-cell desorption/ionization on silicon mass (ICD-MS) and LC-SPE-NMR. These two strategies facilitate the searching and structural determination of unstable natural products. The ICD-MS indicated that only brown hyphae of M. sulfurea can produce malbranpyrroles. The biosynthetic pathway of malbranpyrroles was evidenced by 13C isotope precursors and amino acid feeding experiments. The cytotoxicity data revealed that the conformation of the conjugated system in malbranpyrroles does not affect cytotoxic potency against cancer cell lines. In addition, the chlorine atom was shown to be the pharmacophore for cytotoxicity.

Tubocapsenolide A, a novel withanolide, inhibits proliferation and induces apoptosis in MDA-MB-231 cells by thiol oxidation of heat shock proteins.

Tubocapsenolide A (TA), a novel withanolide-type steroid, exhibits potent cytotoxicity against several human cancer cell lines. In the present study, we observed that treatment of human breast cancer MDA-MB-231 cells with TA led to cell cycle arrest at G(1) phase and apoptosis. The actions of TA were correlated with proteasome-dependent degradation of Cdk4, cyclin D1, Raf-1, Akt, and mutant p53, which are heat shock protein 90 (Hsp90) client proteins. TA treatment induced a transient increase in reactive oxygen species and a decrease in the intracellular glutathione contents. Nonreducing SDS-PAGE revealed that TA rapidly and selectively induced thiol oxidation and aggregation of Hsp90 and Hsp70, both in intact cells and in cell-free systems using purified recombinant proteins. Furthermore, TA inhibited the chaperone activity of Hsp90-Hsp70 complex in the luciferase refolding assay. N-Acetylcysteine, a thiol antioxidant, prevented all of the TA-induced effects, including oxidation of heat shock proteins, degradation of Hsp90 client proteins, and apoptosis. In contrast, non-thiol antioxidants (trolox and vitamin C) were ineffective to prevent Hsp90 inhibition and cell death. Taken together, our results demonstrate that the TA inhibits the activity of Hsp90-Hsp70 chaperone complex, at least in part, by a direct thiol oxidation, which in turn leads to the destabilization and depletion of Hsp90 client proteins and thus causes cell cycle arrest and apoptosis in MDA-MB-231 cells. Therefore, TA can be considered as a new type of inhibitor of Hsp90-Hsp70 chaperone complex, which has the potential to be developed as a novel strategy for cancer treatment.

Cytotoxic ent-abietane diterpenes from Gelonium aequoreum.

Seventeen ent-abietane diterpenes, including gelomulides K-X (1-14), and three known compounds, were isolated from a dichloromethane-soluble extract of Gelonium aequoreum through bioassay-guided fractionation. Their structures were identified by spectroscopic methods, and stereochemistry was confirmed by X-ray crystallographic analysis, CD spectral data, and Mosher's method. The isolates were evaluated for in vitro cytotoxic activity, and compounds 1 and 3 showed moderate cytotoxicity against lung (A549), breast (MDA-MB-231 and MCF7), and liver (HepG2) cancer cell lines.

Cytotoxic withanolides from Tubocapsicum anomalum.

Fifteen new withanolides (1-8, 11-17) and two known withanolides, withanolide D (9) and 17alpha-hydroxywithanolide D (10), were isolated from the stems, roots, and leaves of Tubocapsicum anomalum using bioassay-directed fractionation. The structures were determined by spectroscopic and chemical methods, and the absolute configurations were established by CD analysis and by the Mosher ester method. The structure of 1 and 3 were further confirmed by X-ray crystallographic analysis. Compounds 1, 4-6, 8-10, and 13 showed significant cytotoxic activity against Hep G2, Hep 3B, A-549, MDA-MB-231, MCF-7, and MRC-5 cell lines.

The transgenic Arabidopsis plant system, pER8-GFP, as a powerful tool in searching for natural product estrogen-agonists/antagonists.

The transgenic Arabidopsis plant system, pER8-GFP, may be used as a powerful tool in searching for natural estrogen-agonists/antagonists. Among selected plant extracts and natural products, the method was able to distinguish active extracts (e.g., Glycine max and Pueraria lobata) and pure compounds (e.g., 17beta-estradiol (1), genistein (10), and daidzein (11)) and also to distinguish effects of structural changes on activity. Thus, this rapid sensitive system was proven to be suitable for the discovery of natural products with estrogenic activity.