Biological properties of low molecular mass peptide dendrimers

A series of new, low molecular mass, lysine-based peptide dendrimers with varying distribution of cationic and aromatic groups in the structure were synthesized. They expressed antimicrobial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria as well as against fungal pathogens (Candida albicans). Their cytotoxic, haematotoxic, and genotoxic effects were studied. It appears that degree of branching and steric distribution and types of hydrophobic (aromatic) groups and cationic centres are important components of dendrimeric structure and influence both antimicrobial potency and toxicity. Such 3D structure of our dendrimers mimics that of the natural antimicrobial peptides and can be achieved by application of dendrimer chemistry.     

Statistical analysis of low molecular mass heparin nanoencapsulation

The objective of this study was to use Box-Behnken design (BBD) to investigate the influence of formulation variables on the properties of heparin-loaded poly(lactic-coglycolic acid) (PLGA)-polymethacrylate-RLPO (E-RLPO) nanoparticles (NP) in terms of mean diameter (as size) and drug encapsulation efficiency. The NPs were prepared by the double emulsion solvent evaporation method. The independent variables were: X1 - polymer mass ratio (PLGA:E-RLPO) in the oil phase, X2 - concentration of polyvinyl alcohol (PVA) as emulsion stabilizer, and X3 - volume of the external aqueous phase (W2). Particle size (analyzed by dynamic light scattering) and encapsulation efficiency (EE, estimated by spectrophotometry) were the investigated responses. The polynomial equation obtained from regression analysis of the reduced model (p = 0.0002, F = 25.7952 and R2 = 0.96) provided an excellent fit. The optimal size for the NP was found to be 134.2 ± 16.5 nm with formulation variables of 48.2:61.8, 0.321 (%,m/V) and 263 mL for X1, X2 and X3, respectively. Probably, due to electrostatic interaction between the negatively charged drug and the positively charged E-RLPO, the percent EE of heparin was between 74.4 ± 6.5 % (lowest value) and 92.1 ± 5.3 % (highest value). The data suggest that BBD is a useful tool in rational design of heparin-loaded NPs.     

小檗碱类抗微生物化合物研究进展

小檗碱类化合物是一类具有多种生物活性且大量应用于临床的季铵类异喹啉生物碱。近年来,小檗碱类药物的研究与开发受到广泛关注,且逐渐成为一个发展迅速、充满活力的领域。通过结构修饰所得的小檗碱类衍生物具有良好的抗细菌、抗真菌及抗病毒活性,可通过多种靶点对微生物发挥抑制作用。本文综述小檗碱类衍生物在抗细菌、抗真菌及抗病毒方面的研究与开发进展状况,为进一步研发小檗碱类抗微生物药物提供参考。     

Antimicrobial preservative use in parenteral products: past and present

The following review provides a comprehensive summary of antimicrobial preservatives that are commonly used in licensed parenteral products to date. The information reviewed includes the general properties of the preservatives, the doses and frequency of their use, the classes of the preserved products (peptide, protein, vaccine, and small molecule products), the interactions with other formulation components, and the criteria commonly used for their selection in parental product formulations. It was revealed that phenol and benzyl alcohol are the two most common antimicrobial preservatives used in peptide and protein products, while phenoxyethanol is the most frequently used preservative in vaccines. Benzyl alcohol or a combination of methylparaben and propylparaben are generally found in small molecule parenteral formulations. The key criteria for antimicrobial preservative selection are the preservative's dose, antimicrobial functionality, and effect on the active ingredient. Additionally, the use of spectroscopic techniques (circular dicroism (CD) and fluorescence) and differential scanning calorimetry (DSC) were identified as common techniques used in evaluating an antimicrobial preservative for its impact on the conformational stability of peptide, protein, and vaccine antigens. The future use of preservatives is also discussed, including antimicrobial agents such as peptides, and regulatory requirements for antimicrobial effectiveness testing.     

低分子肝素相对分子质量测定方法

相对分子质量是低分子肝素的重要质量控制指标,本文对5种常用的LMWH相对分子质量测定方法(高效分子排阻色谱法、聚丙烯酰胺凝胶电泳法、光散射法、质谱法、核磁共振法)进行综述。5种方法特点各异,可以根据实验室条件和对相对分子质量测量的要求选择。     

Agarotetrol: a source compound for low molecular weight aromatic compounds from agarwood heating

Agarwood is known to generate a distinct fragrance upon heating and is used as both a medicine and a fragrant wood. Low molecular weight aromatic compounds (LACs) such as benzylacetone are emitted from agarwood on heating and have a sedative effect on mice. These are detected exclusively in the headspace vapor of heated agarwood and are absent in the wood itself; hence, some compounds in agarwood are thought to be converted to LACs by the process of heating. In this study, different fractions obtained from agarwood were analyzed to reveal the source compounds of LACs. Some LACs detected in the resinous agarwood were absent from the non-resinous parts and confirmed as characteristic of the resinous parts. The essential oil and hydrosol of agarwood obtained by distillation were analyzed by gas chromatography–mass spectrometry (GC–MS). Sesquiterpenes were detected in the essential oil, and sesquiterpenes and a variety of LACs were detected in the hydrosol. A hot water extract of agarwood remaining in the distillation flask after distillation was analyzed by high-performance liquid chromatography (HPLC), and agarotetrol was found to be the main compound. Purified agarotetrol was heated in a glass vial and its headspace vapor was analyzed by solid-phase microextraction GC–MS. Benzylacetone and other LACs were detected. These results indicate that agarotetrol, a chromone derivative, contributes to the fragrance of agarwood through the generation of LACs upon heating.     

Comparative study of the high molecular mass fraction and low molecular mass fraction of Sho-saiko-to in a murine immunologically induced liver injury model

We compared the pharmacological actions of the high and low molecular mass fractions of Sho-saiko-to using a murine immunologically induced liver injury model to estimate the roles of these fractions in the expression of the pharmacological action. In a Bacillus Calmette-Guerin (BCG)/lipopolysaccharide (LPS)-induced liver injury model, Sho-saiko-to and both of its fractions significantly reduced the increases in the aminotranseferase levels in serum. They also reduced the increase in the nitric oxide (NOx) level in serum. On the other hand, Sho-saiko-to and its high molecular mass fraction suppressed the increase in plasma NOx level in an LPS-induced endotoxin shock model but its low molecular mass fraction did not. These results suggest the possibility that both fractions act hepatoprotectively in a different manner. We believe that these results can help to elucidate the mechanism of action of ingredients in Sho-saiko-to.     

Antimicrobial action of new imidazolinium compounds

Syntheses and antibacterial activity of 1-ethyl-2-alkyl-3-(alkoxymethyl)- and 1-ethyl-2-alkyl-3-(alkylthiomethyl)imidazolinium chlorides are described. Syntheses of the imidazolinium compounds were performed by reaction of 1-ethyl-2-alkylimidazoline with chloromethylalkyl ether or with chloromethylalkyl sulfide. Antimicrobial properties of obtained compounds was tested on 13 strains of bacteria and fungi. Chlorides with alkylthiomethyl residue showed the highest antimicrobial activity.     

Antimicrobial activity of quaternary ammonium compounds

The antimicrobial properties of two new imidazolium and pyridinium chlorides in comparison with three currently in disinfection compounds applied are described. The following research was performed: resistance of organisms to disinfectants and disinfection of hands. The new 3-methyl-n-dodecylthiomethylpyridinium chlorid was the most active compound.     

The rabbit motilin receptor: molecular characterisation and pharmacology

Following identification of the human motilin receptor, we isolated the rabbit orthologue by PCR amplification and found this to be 85% identical to the open reading frame of the human receptor. The protein encoded was 84% identical to the human polypeptide. In HEK293T cells transfected with the rabbit receptor, motilin concentration-dependently increased intracellular calcium mobilisation (pEC50=9.25). After transfection with Go1alpha, motilin similarly stimulated [35S]GTPgammaS binding (pEC50=8.87). Using both systems, similar values were obtained with the human receptor, with rank-order potencies of motilin=[Nle13]-motilin>erythromycin; ghrelin was ineffective. In circular muscle preparations of rabbit gastric antrum, [Nle13]-motilin 0.1-30 nM concentration-dependently increased the amplitude of electrically-evoked, neuronally-mediated contractions (pEC50=8.3); higher concentrations increased the muscle tension (30-3000 nM). Both responses to [Nle13]-motilin faded rapidly during its continual presence. Rat or human ghrelin 0.01-10 microM were without activity. Erythromycin 30-3000 nM and 10 microM, respectively, increased neuronal activity and muscle tension in rabbit stomach. Unlike [Nle13]-motilin, the increase in neuronal activity did not fade during continual presence of submaximally-effective concentrations of erythromycin; some fade was observed at higher concentrations. We conclude that the pharmacology of the rabbit motilin receptor is similar to the human orthologue and, when expressed as a recombinant, comparable to the native receptor. However, in terms of their ability to increase neuronal activity in rabbit stomach, [Nle13]-motilin and erythromycin are distinguished by different response kinetics, reflecting different rates of ligand degradation and/or interaction with the receptor.     

Correction to: Agarotetrol: a source compound for low molecular weight aromatic compounds from agarwood heating

Journal of Natural Medicines - In the original publication of the article, under the paragraphs “Collection of volatile compound” and “Analysis of essential oil and...     

Polymeric and low molecular mass efflux pump inhibitors for oral drug delivery

Transmembrane located transporter proteins can be responsible for the low bioavailability of orally administered drugs. Drug delivery systems which can overcome this barrier caused by efflux pumps are therefore highly on demand. Within the current review, intestinal located efflux transporters, methods to identify efflux pump substrates and inhibitors as well as strategies to minimize efflux pump mediated transport of drugs are discussed. Methods include in silico screening, transport and accumulation studies and monitoring of the ATPase activity. An emphasis has been placed on efflux pump inhibitors including low molecular mass inhibitors such as cyclosporine, PSC833 or KR30031 and polymeric inhibitors such as myrj, thiomers and cremophor EL. Also formulation approaches to circumvent intestinal segments with high efflux pump expression are briefly addressed.     

The anti-inflammatory compounds of Polygonum bistorta: isolation and characterisation.

A bioassay-guided technique has been used to isolate anti-inflammatory compounds from the dried rhizomes of Polygonum bistorta, for structural identification. Anti-inflammatory activity was detected using the carrageenan-induced rat paw oedema. Two compounds were isolated which significantly suppressed the inflammatory response. Spectral data from EIMS and NMR together with some physical characteristics revealed the identities of the two active compounds as 5-glutinen-3-one and friedelanol. The results indicate that these two compounds largely account for the anti-inflammatory actions of the rhizomes of P. bistorta.     

Protein and low molecular mass thiols as targets and inhibitors of glycation reactions

Protein glycation has been implicated in the aging process as well as the complications of diabetes (retinopathy, neuropathy, nephropathy, and atherosclerosis). The nitrogen substituents of Lys, Arg, and His residues and the N-terminus of proteins are known to be readily glycated. As the thiol group of Cys is a powerful nucleophile, we hypothesized that Cys residues should also be targets of glycation and that low molecular mass thiols may act as protective agents. In this study the role of thiol glycation, induced by dicarbonyls, in protein cross-link formation and damage prevention is examined. It is shown that incubation of creatine kinase with glyoxal results in protein cross-link formation, with this occurring concurrently with loss of thiol groups, enzyme inactivation, and formation of S-carboxymethylcysteine, a product of glyoxal adduction to Cys residues. Cross-links have also been detected between N-acetylcysteine and the Lys-rich protein histone H1, demonstrating the formation of thiol-glyoxal-amine cross-links. Mass spectrometry has been used to characterize some of these cross-links as 2-(alkylthio)acetamides. A range of low molecular mass thiols have been shown to inhibit dicarbonyl adduction to, and cross-linking of, the thiol-free protein lysozyme, consistent with these thiols being alternative (sacrificial) targets of glycation. Some of these thiols are more efficient modulators of glycation than established glycation inhibitors such as aminoguanidine. These data demonstrate that thiols are facile targets of glycation and that low molecular mass thiols are potent glycation inhibitors. These data may aid the design of therapeutic agents for the treatment of the complications of diabetes.