Preparation, antioxidant and tyrosinase inhibitory activities of chitosan oligosaccharide-hydroxypyridinone conjugates.

Two novel chitosan oligosaccharide (COS)-hydroxypyridone (HPO) conjugates were prepared by reacting chitosan oligosaccharide with 2-chloromethyl-5-hydroxypyridone (HPO), which was synthesized by a series of reactions starting from kojic acid. The degree of substitution of COS-HPO2 reached 1.2, with a yield of 74.9%. The structure of the two conjugates (COS-HPO1 and COS-HPO2) was identified by NMR and FT-IR analysis. The two conjugates showed significantly higher free radical (DPPH•, ABTS+• and •OH) scavenging activity and reducing power than those of COS and HPO (p < 0.05). Both COS-HPO1 and COS-HPO2 possessed significantly stronger tyrosinase inhibitory activity than those of COS, with IC50 values of 0.67 and 0.28 mg/mL for monophenolase, 0.73 and 0.30 mg/mL for diphenolase, respectively. In addition, the conjugates were found to be non-toxic to RAW264.7 macrophages and MRC-5 human lung cells. This work proposes a facile method to enhance the oxidative and tyrosinase inhibitory properties of COS.

Micropyrones A and B, two new α-pyrones from the actinomycete Microbacterium sp. GJ312 isolated from Glycyrrhiza uralensis Fisch.

Two new α-pyrones, micropyrones A (1) and B (2), along with four known γ-pyrones, nocapyrone D (3), nocapyrone A (4), marinactinone A (5), and nocapyrone H (6), were isolated from the culture extract of actinomycete Microbacterium sp. GJ312, which was isolated from Glycyrrhiza uralensis. The structures of these compounds were identified by analysis of spectral data. They are the first α- and γ-pyrones reported from the genus Microbacterium. The antibacterial activity of all compounds against Staphylococcus aureus and methicillin resistant S. aureus was evaluated. However, none of them showed significant activity. This study represents the first phytochemical example of a Glycyrrhiza-derived actinomycete.

A novel chitosan oligosaccharide derivative: Synthesis, antioxidant and antibacterial properties.

A novel thioether chitosan oligosaccharide (COS-All-Tio) was prepared by the reaction of chitosan oligosaccharide (COS) with 3-bromopropene, followed by the coupling with tiopronin (Tio) using a thiol-ene reaction. The degree of substitution of COS-All-Tio reached 1.48. The structure of COS-All-Tio was identified by IR, NMR spectra. It was found that COS-All-Tio possessed more potent antioxidant activities than COS. The IC50 values of COS-All-Tio for scavenging DPPH, ABTS+ and OH were 0.31, 0.39 and 0.73 mg/mL, respectively, while the corresponding values for COS were 0.66, 2.89 and 1.41 mg/mL, respectively. COS-All-Tio was also found to possess much stronger antibacterial effect than COS against five bacteria strains (Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes, Escherichia coli and Pseudomonas aeruginosa). Further, COS-All-Tio was found to be non-toxic to RAW264.7 macrophages and MRC-5 human lung cells. This work provides a convenient way to improve the antioxidant and antibacterial activities of COS.

Star fruit extract and C-glycosylated flavonoid components have potential to prevent air pollutant-induced skin inflammation and premature aging.

Air pollution adversely affects skin, leading to skin inflammation and premature skin aging. Plant derived antioxidant compounds have been considered to be promising in discovery of effective agents for the protection of skin from the damage by air pollutants. Our previous studies demonstrated that Averrhoa carambola fruit (known as star fruit) is rich in flavonoid C-glycosides with unique structures and potent antioxidant activity. Thus, the star fruit extract (SFE) and main flavonoid C-glycoside components, carambolasides I, J, and P (1-3), carambolaflavone B (4), and isovitexin 2″-O-α-L-rhamnoside (5), were investigated for the activity against air pollutant stress in human epidermis. As a result, SFE and compounds 1-5 exhibited significant inhibitory activity against protein carbonylation in oxidative-stressed stratum corneum with the best activity being shown by compound 3. SFE and compounds 2-5 were also active against engine exhaust-induced protein carbonylation in stratum corneum. When further evaluated, SFE and compound 3 significantly inhibited gene expression of the key inflammation mediators IL-1α and COX-2 in PM-stressed keratinocytes. The results indicated that SFE and the flavonoid C-glycosides are potentially effective against air pollutant-induced skin inflammation and premature aging.

Structurally Diverse Polycyclic Salicylaldehyde Derivative Enantiomers from a Marine-Derived Fungus Eurotium sp. SCSIO F452.

To enlarge the chemical diversity of Eurotium sp. SCSIO F452, a talented marine-derived fungus, we further investigated its chemical constituents from a large-scale fermentation with modified culture. Four pairs of new salicylaldehyde derivative enantiomers, euroticins F-I (1-4), as well as a known one eurotirumin (5) were isolated and characterized. Compound 1 features an unprecedented constructed 6/6/6/5 tetracyclic structures, while 2 and 3 represent two new types of 6/6/5 scaffolds. Their structures were established by comprehensive spectroscopic analyses, X-ray diffraction, 13C NMR, and electronic circular dichroism calculations. Selected compounds showed significant inhibitory activity against α-glucosidase and moderate cytotoxic activities against SF-268, MCF-7, HepG2, and A549 cell lines.

Purification and Biological Activities of Enzymatically Degraded Sargassum fusiforme Polysaccharides.

Enzymatic hydrolysate of the crude polysaccharide (SFP) extracted from Sargassum fusiforme was purified by column DEAE-52 and Sephadex G-100 to yield four components, namely, ESFP1, ESFP2, ESFP3 and ESFP4. These components were characterized by chemical composition assay, GC/MS, HPGPC, UV and FT-IR techniques. The in vitro antioxidant activities of the four purified fractions were investigated by measuring their radical scavenging activity and reducing power. The results suggested that all the four components possess good antioxidant activities. Among them, ESFP1 was found to possess the strongest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and hydroxyl radical-scavenging activity, and the greatest ferric reducing power. The immunomodulatory effect of these four polysaccharides was demonstrated by their ability to promote proliferation, and to enhance both phagocytic activity and NO release in a macrophage RAW264.7 model. The results revealed that the bioactivities of the polysaccharides are related to their molecular weight, and the uronic acid and sulfate contents.

Asperorydines N-P, three new cyclopiazonic acid alkaloids from the marine-derived fungus Aspergillus flavus SCSIO F025.

Three new tricyclic cyclopiazonic acid (CPA) related alkaloids asperorydines N-P (1-3), together with six known compounds (4-9) were isolated and characterized from the fungus Aspergillus flavus SCSIO F025 derived from the deep-sea sediments of South China Sea. The structures including absolute configurations of 1-3 were deduced from spectroscopic data, X-ray diffraction analysis, and electronic circular dichroism (ECD). All compounds were evaluated for the antioxidative activities against DPPH, cytotoxic activities against four tumor cell lines (SF-268, HepG-2, MCF-7, and A549), and antimicrobial activities. Compound 9 showed significant radical scavenging activities against DPPH with an IC50 value of 62.23 µM and broad-spectrum cytotoxicities against four tumor cell lines with IC50 values ranging from 24.38 to 48.28 µM. Furthermore, compounds 4-9 exhibited weak antimicrobial activities against E scherichia coli, and compound 9 also showed antibacterial activity against Bacillus thuringiensis, Micrococcus lutea, Staphylococcus aureus, Bacillus subtilis, Methicillin resistant Staphylococcus aureus.

Bioactive Diarylheptanoids from Alpinia coriandriodora.

Eight new diarylheptanoids, coriandralpinins A-H (1-8), were isolated from the rhizomes of Alpinia coriandriodora, an edible plant of the ginger family. Their structures, including the absolute configurations, were established by extensive spectroscopic analysis and ECD calculations. Compounds 1-8 have a 1,5-O-bridged diarylheptanoid structure featuring polyoxygenated aryl units. When evaluated for intracellular antioxidant activity using t-BHP stressed RAW264.7 macrophages, all these compounds scavenged reactive oxygen species (ROS) in a concentration-dependent manner. Compounds 3 and 5 also showed inhibitory activity against NO release in LPS-induced RAW 264.7 cells. Six known flavonols, 7,4'-di-O-methylkaempferol, 7-O-methylquercetin, 7,4'-di-O-methylquercetin, 7,3',4'-tri-O- methylquercetin, kaempferol 3-O-ß-D-(6-O-α-L-rhamnopyranosyl)glucopyranoside, and 3-O-ß-D-glucopyranuronosylquercetin were also isolated and characterized from the rhizomes.

Dihydrochalcones from the leaves of Lithocarpus litseifolius.

Three new phlorizin derivatives, 6"-O-vanilloylphlorizin (1), 6"-O-(4-hydroxybenzoyl)phlorizin (2), 6"-O-feruloylphlorizin (3), along with four known dihydrochalcones, phlorizin (4), 3-hydroxyphlorizin, trilobatin, and 6"-O-acetylphlorizin were isolated from the leaves of Lithocarpus litseifolius. Their structures were established by analysis of extensive spectroscopic data. The new compounds were shown to be non-cytotoxic when tested against A549, HeLa, HepG2, and MCF-7 cell lines.

Synthesis and Cytotoxic Property of Annonaceous Acetogenin Glycoconjugates.

BACKGROUND: Annonaceous acetogenins (ACGs) are secondary metabolites produced by the Annonaceae family and display potent anticancer activity against various cancer cell lines. Squamocin and bullatacin are two examples of ACGs that show promising antitumor activity; however, preclinical data are not sufficient partly due to their being highly lipophilic and poorly soluble in water. These compounds also display high toxicity to normal cells. Due to these disadvantageous properties, the therapeutic potential of squamocin and bullatacin as antitumor agents has not been fully evaluated. METHODS: In order to enhance their water solubility and potentially improve their cancer targeting, squamocin and bullatacin were conjugated to a glucose or galactose to yield glycosylated derivatives by direct glycosylation or the Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) reaction (the click reaction). The synthesized compounds were evaluated for their anticancer property against HeLa, A549 and HepG2 cancer cell lines using MTT assay. RESULTS: Nine glycosyl derivatives were synthesized and structurally characterized. Most of them show comparable in vitro cytotoxicity against HeLa, A549 and HepG2 cancer cell lines as their parent compounds squamocin and bullatacin. It appears that the type of sugar residue (glucose or galactose), the position at which the sugar residue is attached, and whether or not a linking spacer is present do not affect the potency of these derivatives much. The solubility of galactosylated squamocin 13 in phosphate buffer saline (PBS, pH = 7) is greatly improved (1.37 mg/mL) in comparison to squamocin (not detected in PBS). CONCLUSION: The conjugation of a glucose or galactose to squamocin and bullatacin yields glycosyl derivatives with similar level of anticancer activity in tested cell lines. Further studies are needed to demonstrate whether or not these compounds show reduced toxicity to normal cells and their therapeutic potential as antitumor agents.

Effect of enzymatic degraded polysaccharides from Enteromorpha prolifera on the physical and oxidative stability of fish oil-in-water emulsions.

To explore the potential application of enzymatic degraded polysaccharides from Enteromorpha prolifra (EEP) as antioxidant in fish oils, a stable fish oil emulsion system incorporating EEP was established. Effects of emulsifier (Tween 80, gum arabic and lecithin) and EEP concentration on the physical characteristics of fish oil emulsions were investigated. The results indicated that Tween 80 was the best choice, and 1% (w/w) of EEP was the optimum concentration for the preparation of fish oil emulsions. Influence of EEP on the oxidative stability and physical stability of fish oil emulsions was compared with that of antioxidants VE and TBHQ by determining the physical properties, lipid hydroperoxide formation, secondary reaction products formation, pH and long chain polyunsaturated fatty acid content, during storage at 45 °C. The results indicated that the fish oil emulsion system (5% oil, 1% EEP and 1% Tween 80, w/w) possessed good physical and oxidative stabilities.

Co-immobilization of pectinase and glucoamylase onto sodium aliginate/graphene oxide composite beads and its application in the preparation of pumpkin-hawthorn juice.

Co-immobilization of pectinase and glucoamylase onto sodium alginate/graphene oxide beads was achieved by N,N'-dicyclohexylcarbodiimide/N-hydroxysuccinimide as activating agent. The co-immobilized pectinase-glucoamylase (I-PG) prepared under optimal conditions (pH 4.0, 40°C and 35 min) possessed pectinase activity of 1,227.5 ± 36.5U/g and glucoamylase activity of 1,027.2 ± 29.2U/g, with activity recovery of 73.8% and 85.2%, respectively. Both pectinase and glucoamylase in I-PG possessed wider pH tolerance and superior thermal stability to those of their free counterparts. Reusability studies indicated that both enzymes in I-PG retained over 60% of initial activity after six times of reuse. Conditions for the hydrolysis of the pumpkin-hawthorn compound juice by I-PG were optimized using orthogonal experiments. After treatment with I-PG, light transmittance, soluble solids, and reducing sugar content in the resulting juice increased significantly, whereas soluble protein and pectin content decreased appreciably. Therefore, the use of I-PG provided an effective and feasible method for improving quality of the pumpkin-hawthorn juice. PRACTICAL APPLICATIONS: In order to overcome the drawbacks of using free pectinase and glucoamylase, an effective method for the co-immobilization of these two enzymes onto sodium alginate/graphene oxide beads was developed. The co-immobilized pectinase/glucoamylase developed in this study could be applied in the clarification of juice rich in pectin and starch.

Xylarodons A and B, new hexaketides from the endophytic fungus Xylaria sp. SC1440.

Two new hexaketides, xylarodons B (1) and C (2), were isolated from solid cultures of the endophytic fungus Xylaria sp. SC1440. The structures of these compounds were elucidated on the basis of detailed 1D, 2D NMR, and HRESIMS analysis. Their absolute configurations were established by experimental and TDDFT calculated ECD spectra. The isolated compounds were evaluated for cytotoxic and tyrosinase inhibitory activity.

Antioxidant and antimicrobial evaluation of carboxymethylated and hydroxamated degraded polysaccharides from Sargassum fusiforme.

In order to improve the bioactivity of the polysaccharide from Sargassum fusiforme (PSF), the degraded polysaccharide (DPSF) was modified by carboxymethylation, yielding carboxymethylated degraded polysaccharides (CDPSF), which were further modified to generate hydroxamated derivatives (HCDPSF). Both CDPSF and HCDPSF were characterized by Fourier transform infrared spectroscopy. The molecular weight of CDPSF and HCDPSF was found to be 354 kDa and 375 kDa, respectively. The in vitro antioxidant activity of CDPSF and HCDPSF was evaluated by determining the radical scavenging ability and total antioxidant activity. The results indicated that the antioxidant activity of CDPSF and HCDPSF was significantly improved when compared to those of DPSF. Antimicrobial assays indicated that both CDPSF and HCDPSF possessed a marked antimicrobial ability, while DPSF did not exhibit such effects under the same conditions. Such polysaccharide derivatives have potentials in the pharmaceutical and food industries.

Eurotiumins A⁻E, Five New Alkaloids from the Marine-Derived Fungus Eurotium sp. SCSIO F452.

Three new prenylated indole 2,5-diketopiperazine alkaloids (1⁻3) with nine known ones (5⁻13), one new indole alkaloid (4), and one new bis-benzyl pyrimidine derivative (14) were isolated and characterized from the marine-derived fungus Eurotium sp. SCSIO F452. 1 and 2, occurring as a pair of diastereomers, both presented a hexahydropyrrolo[2,3-b]indole skeleton. Their chemical structures, including absolute configurations, were elucidated by 1D and 2D NMR, HRESIMS, quantum chemical calculations of electronic circular dichroism, and single crystal X-ray diffraction experiments. Most isolated compounds were screened for antioxidative potency. Compounds 3, 5, 6, 7, 9, 10, and 12 showed significant radical scavenging activities against DPPH with IC50 values of 13, 19, 4, 3, 24, 13, and 18 µM, respectively. Five new compounds were evaluated for cytotoxic activities.

Characterization and immunological activity of polysaccharides from Ixeris polycephala.

A water-soluble polysaccharide, named KMCP, was isolated and purified from edible plant Ixeris polycephala by using DEAE-52 cellulose chromatography. Its structure was determined by chemical analysis, methylation analysis, and NMR analysis, coupled with characterization by scanning electron spectroscopy (SEM). The resulting data indicated that KMCP was an arabinogalactan, with an average molecular weight of 1.95×106Da, which was mainly composed of arabinose and galactose in a relative molar ratio of 28.1% and 70.3%, respectively. The structure of KMPC was characterized as 72.5% of (1→4)-ß-Galp residues interspersed with 27.5% of (1→4,6)-ß-Galp residues in the main chain, and the branches were composed of (1→5)-α-Araf moieties or α-Araf (1→5) α-Araf (1→disaccharide moieties attached at O-6 of the (1→4,6)-ß-Galp residues. KMCP was revealed to be capable of exhibiting macrophage-mediated innate immune responses via enhancing phagocytosis of macrophages and increasing production of NO, activating NF-κB signaling pathway and promoting the mice spleen cells proliferation in a dose-dependent manner within the test concentrations (10.0-200.0µg/mL). These results suggested that KMCP could potentially be an effective and safe immunomodulator valuable to be utilized in pharmacological fields or in the development of functional foods.

Characterization of Sesquiterpene Dimers from Resina Commiphora That Promote Adipose-Derived Stem Cell Proliferation and Differentiation.

The new sesquiterpene dimers commiphoroids A-D (1-4) were isolated from Resina Commiphora, and their structures were assigned by spectroscopic methods and X-ray diffraction analysis. Compounds 1 and 2 are stereoisomers of putative [2 + 4]-cycloaddition reactions, and 3 is a trinorsesquiterpene dimer containing a 6/6/5/6/6/6 hexacyclic framework, while 4 possesses a 8-oxabicyclo[3.2.1]oct-6-ene skeletal core. Plausible biosynthetic pathways for 1-4 are proposed. Biochemical studies show that compound 1 promotes ca. 60% expression of keratinocyte-specific markers in adipose-derived stem cells at 10 µM.

Advanced technology for nanostarches preparation by high speed jet and its mechanism analysis.

Nanostarches were successfully prepared by high speed jet (HSJ) after pretreatment of micronization. The nanostarches were obtained at the conditions of micronization treatment for 60min, and then one cycle at 240MPa of HSJ (188.1nm). Moreover, after HSJ treated for three cycles, the particle size could reach the level of nanometer materials (66.94nm). The physicochemical properties of nanostarches had been characterized. Rapid Visco-Analysis (RVA) showed that the viscosity of nanostarches significantly decreased compared with native tapioca starch and slightly decreased with increasing processing cycles of HSJ. Steady shear analysis indicated that all samples displayed pseudoplastic, shear-thinning behavior, while the flow curves of nanostarches were little impact by the processing cycles of HSJ. X-ray diffraction analysis showed that the complete destruction of tapioca starch crystalline structure was obtained after HSJ treatment. Molecular characteristics determination suggested that the degradation of amylopectin chains occurred after the treatment of micronization and HSJ, which was proved by the decrease of weight-average molar mass. The results demonstrated that nanostarches were obtained due to the breakdown of starch molecules. This study will provide useful information of the nanostarches for its potential industrial application.

Pteridic acids C-G spirocyclic polyketides from the marine-derived Streptomyces sp. SCSGAA 0027.

Five new pteridic acids C-G (1-5) were isolated from a culture broth of the marine-derived actinomycete Streptomyces sp. SCSGAA 0027. Their complete structures were elucidated on the basis of NMR data, modified Mosher's method and quantum chemical calculations. Furthermore, their cytotoxicity, antiviral and antimicrobial activities were also evaluated.

Spiro Meroterpenoids from Ganoderma applanatum.

Spiroapplanatumines A-Q (1-12, 14-16, 18, and 20), new spiro meroterpenoids respectively bearing a 6/5/7 or 6/5/5 ring system, along with three known compounds, spirolingzhines A, B, and D, were isolated from the fruiting bodies of the fungus Ganoderma applanatum. Their structures including absolute configurations were assigned by using spectroscopic methods, ECD and 13C NMR calculations, and single-crystal X-ray diffraction analysis. Biological evaluation of all the compounds disclosed that compounds 7 and 8 inhibited JAK3 kinase with IC50 values of 7.0 ± 3.2 and 34.8 ± 21.1 µM, respectively.