Grafting of vinyl acetate onto chitosan and biocidal activity of the graft copolymers

The reaction process of polycarbosilane (PCS) fiber cured by cyclohexene vapor has been studied and compared with that of PCS fiber cured by air. The influence of curing temperature on Si? H bond reaction degree and gel content, the structure and composition of PCS were investigated by FTIR, EA, TGA, NMR, and GC‐MS. The results showed that, Si? H bond in the molecular structure of PCS reacted during cyclohexene curing process and the reaction degree increased when the curing temperature increases. Simultaneously, gel content of PCS fiber rapidly increased till PCS fiber became infusible. Si? H radical and Si? CH₂ radicals formed Si? CH₂? Si crosslinking of PCS molecules through the agency of cyclohexene. Some cyclohexyls linked to principal chain of PCS, which was proven by ¹³C‐CPMAS‐NMR, and broke off, and cyclohexane and some monosilane are generated as byproducts when temperature increased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Sensitivity of four foodborne moulds to essential oils from turkish spices,herbs and citrus peel

The antifungal effects of 22 essential oils from Turkish spices, herbs and citrus peel on four foodborne moulds were evaluated for fungistatic and fungicidal activity. The most active oils were wild thyme (Thymus rariflorus L) and thyme (Thymus serpyllum L). Parsley (Penloselinum sativum Hoffin) and savory (Satureja hortensis L) oils were found to be the least active oils. Rhizopus sp displayed the greatest tolerance, and the most sensitive mould was Penicillium chrysogenum. Prolonged incubations reduced the fungistatic and fungicidal effects of oils. It was concluded that some oils may be useful as mould inhibitors at food additive levels.     

Substantivity of sunscreens: an appraisal of some quaternary ammonium sunscreens

Two series of quaternary ammonium UV-B sunscreens, derived from salicylic acid (S) and from p -methoxycinnamic acid (C), and containing N-alkyl chains of different length (C₂ to C₁₆) were prepared and submitted to substantivity tests on animal (wool) keratin, and to microbiological tests. A direct correlation between substantivity and antimicrobial/antifungal activity was observed in all cases, the compounds bearing C₁₂ alkyl chains displaying peak values. The C-derivatives, when compared with the S-derivatives, showed relatively higher substantivity and sunscreen index (SI) values, coupled with lower antibacterial activity. The substantivity-microbiological activity correlations and the particular behaviour of the C₁₂ derivatives are briefly discussed in the light of the existing literature data. On the basis of the experimental results, possible guidelines for the development of substantive and non-antibacterial (and possibly, non-irritant) quaternary ammonium sunscreens are indicated.
La substantivité des filtres solaires     

Microwave assisted synthesis,spectroscopic, thermal,and antifungal studies of some lanthanide（Ⅲ） complexes with a heterocyclic bishydrazone

A bishydrazone formed by the condensation of isatinmonohydrazone and salicylaldehyde reacted with lanthanide（Ⅲ） chloride to form complexes of the type [Ln（HISA）2Cl3], where, Ln=La（Ⅲ）, Ce（Ⅲ）, Pr（Ⅲ）, Nd（Ⅲ）, Sm（Ⅲ）, Eu（Ⅲ）, or Gd（Ⅲ） and HISA= [（2-hydroxybenzaldehyde）-3-isatin]bishydrazone. Both reactions were carried out under microwave conditions. The ligand and the metal complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility measurements, UV visible, infrared, far infrared, and proton NMR spectral data. The ligand acted as neutral tridentate, coordinating through the carbonyl oxygen, azomethine nitrogen, and phenolic oxygen without deprotonation. The ligand and lanthanum（Ⅲ） complex were subjected to X-ray diffraction studies. The X-ray diffraction pattern of ligand exhibited its crystalline nature and that of the lanthanum（Ⅲ） complex indicated its amorphous character. The thermal decomposition behaviour of the complex, [La（HISA）2Cl3], was examined in the temperature range of 40-800 ℃ using TG, DTG, and DTA. The ligand and the metal complexes were screened for their antifungal activities.     

DyP-Type Peroxidases: Recent Advances and Perspectives

In this review, we chart the major milestones in the research progress on the DyP-type peroxidase family over the past decade. Though mainly distributed among bacteria and fungi, this family actually exhibits more widespread diversity. Advanced tertiary structural analyses have revealed common and different features among members of this family. Notably, the catalytic cycle for the peroxidase activity of DyP-type peroxidases appears to be different from that of other ubiquitous heme peroxidases. DyP-type peroxidases have also been reported to possess activities in addition to peroxidase function, including hydrolase or oxidase activity. They also show various cellular distributions, functioning not only inside cells but also outside of cells. Some are also cargo proteins of encapsulin. Unique, noteworthy functions include a key role in life-cycle switching in Streptomyces and the operation of an iron transport system in Staphylococcus aureus, Bacillus subtilis and Escherichia coli. We also present several probable physiological roles of DyP-type peroxidases that reflect the widespread distribution and function of these enzymes. Lignin degradation is the most common function attributed to DyP-type peroxidases, but their activity is not high compared with that of standard lignin-degrading enzymes. From an environmental standpoint, degradation of natural antifungal anthraquinone compounds is a specific focus of DyP-type peroxidase research. Considered in its totality, the DyP-type peroxidase family offers a rich source of diverse and attractive materials for research scientists.     

Prenylated Flavonoids with Potential Antimicrobial Activity: Synthesis,Biological Activity,and In Silico Study

Prenylated flavonoids are an important class of naturally occurring flavonoids with important biological activity, but their low abundance in nature limits their application in medicines. Here, we showed the hemisynthesis and the determination of various biological activities of seven prenylated flavonoids, named 7–13, with an emphasis on antimicrobial ones. Compounds 9, 11, and 12 showed inhibitory activity against human pathogenic fungi. Compounds 11, 12 (flavanones) and 13 (isoflavone) were the most active against clinical isolated Staphylococcus aureus MRSA, showing that structural requirements as prenylation at position C-6 or C-8 and OH at positions C-5, 7, and 4′ are key to the antibacterial activity. The combination of 11 or 12 with commercial antibiotics synergistically enhanced the antibacterial activity of vancomycin, ciprofloxacin, and methicillin in a factor of 10 to 100 times against drug-resistant bacteria. Compound 11 combined with ciprofloxacin was able to decrease the levels of ROS generated by ciprofloxacin. According to docking results of S enantiomer of 11 with ATP-binding cassette transporter showed the most favorable binding energy; however, more studies are needed to support this result.     

樟脑酸基双酰肼化合物的合成及其抑菌活性

以樟脑酸为原料,经过脱水反应制备樟脑酸酐,再与芳酰肼发生N-酰化反应,合成得到10个新型樟脑酸基双酰肼化合物3a～3j。初步探索了合成条件,并利用FT-IR、1H NMR、13C NMR和ESI-MS等多种手段对目标产物作了结构表征。初步的生物活性测试表明,在50 mg/L浓度下,部分化合物表现出良好的抑菌活性,其中樟脑酸基烟酰肼3h对苹果轮纹病菌的抑制率高达96.3%,优于阳性对照嘧菌酯。     

Potent Synergy between Spirocyclic Pyrrolidinoindolinones and Fluconazole against Candida albicans

A spiroindolinone, (1S,3R,3aR,6aS)‐1‐benzyl‐6′‐chloro‐5‐(4‐fluorophenyl)‐7′‐methylspiro[1,2,3a,6a‐tetrahydropyrrolo[3,4‐c]pyrrole‐3,3′‐1H‐indole]‐2′,4,6‐trione, was previously reported to enhance the antifungal effect of fluconazole against Candida albicans. A diastereomer of this compound was synthesized, along with various analogues. Many of the compounds were shown to enhance the antifungal effect of fluconazole against C. albicans, some with exquisite potency. One spirocyclic piperazine derivative, which we have named synazo‐1, was found to enhance the effect of fluconazole with an EC₅₀ value of 300 pM against a susceptible strain of C. albicans and going as low as 2 nM against some resistant strains. Synazo‐1 exhibits true synergy with fluconazole, with an FIC index below 0.5 in the strains tested. Synazo‐1 exhibited low toxicity in mammalian cells relative to the concentrations required for antifungal synergy.     

A New and Practical Synthetic Method for the Synthesis of 6-O-Methyl-scutellarein: One Metabolite of Scutellarin in Vivo

Scutellarin (1) has been used for the treatment of angina pectoris, cerebral infarction and coronary heart disease with a large market share in China. Pharmacokinetic studies on scutellarin showed that scutellarin (1) is readily converted into its metabolites in vivo. In this paper, a new and practical synthetic method for the synthesis of 6-O-methyl-scutellarein (3) (one metabolite of scutellarin in vivo) is reported. The benzyl bromide was firstly used to selectively replace the acetyl group at C-7 in 7, and was then used to protect the hydroxy groups at C-4'' in 10, 6-O-methyl-scutellarein (3) is obtained in high yield through these methods.     

Structure and antimicrobial activity relationship of quaternary N‐alkyl chitosan derivatives against some plant pathogens

In the present work, quaternary chitosans as water‐soluble compounds were prepared based on three‐step process. Schiff bases were firstly synthesized by the reaction between the amino groups of chitosan with aliphatic aldehydes followed by a reduction with sodium borohydride (NaBH₄) to form N‐(alkyl) chitosans. N,N,N‐(dimethyl alkyl) chitosans were then obtained by a reaction of chitosan containing N‐butyl, N‐pentyl, N‐hexyl, N‐heptyl, and N‐octyl substituents with methyl iodide. The compounds were characterized using IR and NMR spectroscopy. Subsequent experiments were conducted to test their antimicrobial activities against the most economic plant pathogenic bacteria of crown gall disease Agrobacterium tumefaciens, soft mold disease Erwinia carotovora, fungi of grey mold Botrytis cinerea, root rot disease Fusarium oxysporum, and damping off disease Pythium debaryanum. Quaternary chitosans enhanced the antibacterial activity and N,N,N‐(dimethyl pentyl) chitosan was the most active one with Minimum Inhibitory Concentration (MIC) of 750 and 1225 mg/L against A. tumefaciens and E. carotovora, respectively. All quaternized chitosans gave stronger antifungal activities than chitosan where N,N,N‐(dimethyl pentyl) chitosan and N,N,N‐(dimethyl octyl) chitosan were significantly the highest in mycelial growth inhibiation against B. cinerea (EC₅₀ = 908 and 383 mg/L, respectively), F. oxysporum (EC₅₀ = 871 and 812 mg/L, respectively), and P. debaryanum (EC₅₀ = 624 and 440 mg/L, respectively). In addition, spore germination of B. cinerea and F. oxysporum was significantly affected with the compounds at the tested concentrations and the inhibition activity was increased with an increase in the chain length of the alkyl substituent. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010