Controlling the Site Selectivity in Acylations of Amphiphilic Diols: Directing the Reaction toward the Apolar Domain in a Model Diol and the Midecamycin A1 Macrolide Antibiotic.

Seeking to improve the site selectivity of acylation of amphiphilic diols, which is induced by imidazole-based nucleophilic catalysts and directs the reaction toward apolar sites, as we recently reported, we examined a new improved catalytic design and an alteration of the acylating agent. The new catalysts performed slightly better selectivity-wise in the model reaction, compared to the previous set, but notably could be prepared in a much more synthetically economic way. The change of the acylating agent from anhydride to acyl chloride, particularly in combination with the new catalysts, accelerated the reaction and increased the selectivity in favor of the apolar site. The new selectivity-inducing techniques were applied to midecamycin, a natural amphiphilic antibiotic possessing a secondary alcohol moiety in each of its two domains, polar as well as apolar. In the case of the anhydride, a basic dimethylamino group, decorating this substrate, overrides the catalyst's selectivity preference and forces selective acylation of the alcohol in the polar domain with a more than 91:1 ratio of the monoacylated products. To counteract the internal base influence, an acid additive was used or the acylating agent was changed to acyl chloride. The latter adjustment leads, in combination with our best catalyst, to the reversal of the ratio between the products to 1:11.

Design, synthesis and activity against drug-resistant bacteria evaluation of C-20, C-23 modified 5-O-mycaminosyltylonolide derivatives.

With the increasing incidence of antibiotic resistance, there is an urgent need to develop new antibiotics with excellent activity against drug-resistant bacteria. Three novel series of tylosin semisynthetic derivatives were designed, synthesized and evaluated for their antibacterial activities against various Gram-positive and Gram-negative bacteria. Among these derivatives, compound C-2 demonstrated potent antibacterial activity against both gram-positive and gram negative bacteria, and non mutagenic. More importantly, compound C-2 displayed high antimicrobial potency against Gram-positive bacteria in a murine model, and was found to be more efficient than tildipirosin. Thus, compound C-2 had great potential as a promising lead compound for the treatment of bacterial infection.

Midecamycin Is Inactivated by Several Different Sugar Moieties at Its Inactivation Site.

Glycosylation inactivation is one of the important macrolide resistance mechanisms. The accumulated evidences attributed glycosylation inactivation to a glucosylation modification at the inactivation sites of macrolides. Whether other glycosylation modifications lead to macrolides inactivation is unclear. Herein, we demonstrated that varied glycosylation modifications could cause inactivation of midecamycin, a 16-membered macrolide antibiotic used clinically and agriculturally. Specifically, an actinomycetic glycosyltransferase (GT) OleD was selected for its glycodiversification capacity towards midecamycin. OleD was demonstrated to recognize UDP-D-glucose, UDP-D-xylose, UDP-galactose, UDP-rhamnose and UDP-N-acetylglucosamine to yield corresponding midecamycin 2'-O-glycosides, most of which displayed low yields. Protein engineering of OleD was thus performed to improve its conversions towards sugar donors. Q327F was the most favorable variant with seven times the conversion enhancement towards UDP-N-acetylglucosamine. Likewise, Q327A exhibited 30% conversion enhancement towards UDP-D-xylose. Potent biocatalysts for midecamycin glycosylation were thus obtained through protein engineering. Wild OleD, Q327F and Q327A were used as biocatalysts for scale-up preparation of midecamycin 2'-O-glucopyranoside, midecamycin 2'-O-GlcNAc and midecamycin 2'-O-xylopyranoside. In contrast to midecamycin, these midecamycin 2'-O-glycosides displayed no antimicrobial activities. These evidences suggested that besides glucosylation, other glycosylation patterns also could inactivate midecamycin, providing a new inactivation mechanism for midecamycin resistance. Cumulatively, glycosylation inactivation of midecamycin was independent of the type of attached sugar moieties at its inactivation site.

Production of antibiotic carbomycin from Streptomyces graminofaciens with high lipid content mutation.

The most important tools in killing and overcoming on the microbes and pathogens that cause diseases in medicine and/or in agriculture are the antibiotics. The discovery and synthesis of the microbial natural products or antibiotics has greatly developed genetically and biotechnologically quickly in the last decades. It is necessary to access this great genetic diversity by finding ways to increase the level of expression of these biosynthetic pathways. In this study, we carried out an improvement in the antibiotic production of weak Streptomyces graminofaciens strain NBR9 that has high lipid content; using Ultra-Violet irradiation mutagenesis. This strain was isolated from the Northern Region in the kingdom of Saudi Arabia and identified biochemically and confirmed genetically by sequencing of the 16S rRNA gene as Streptomyces graminofaciens NBR9; Accession No. (MN640578). The resultant mutant strain showed increasing in their antimicrobial activities. The methods and techniques used for the antibiotic extraction, purification, characterization and identification proved that the obtained antibiotic is same with antibiotic Carbomycin.

Universal response method for the quantitative analysis of multi-components in josamycin and midecamycin using liquid chromatography coupled with charged aerosol detector.

Josamycin and midecamycin are consisted of three groups of components with different ultraviolet maximum absorption wavelengths (λmax), which are 231 nm, 280 nm and 205 nm. The quantitative analysis of all these components is challengeable due to the absence of the respective reference substances. To address this problem, universal and reliable methods were developed using high performance liquid chromatography coupled with charged aerosol detector (HPLC-CAD) for the quantitative analysis of components in josamycin and midecamycin. The chromatographic conditions and CAD parameters setting were optimized. Subsequently, the components were identified using HPLC coupled with ion trap/time-of-flight mass spectrometry (IT/TOF MS). The developed methods were validated by assessing linearity, limit of quantitation (LOQ), accuracy, precision and robustness. Good separations were achieved for all components and the adjustment of the filter valve and power function value efficiently improved sensitivity. The developed methods were more comprehensive than current HPLC-UV method. The experimental results demonstrated good linearity with coefficients of determination (R2) greater than 0.999 in the range of 0.002-0.30 mg mL-1. The limits of detection (LOD) were ranging from 1.8 to 2.0 µg·mL-1. The intra-day and inter-day RSD values were less than 2.0 % (n = 6) and 5.6 % (n = 9) respectively. The recoveries were 95.0 %-124.0 % at the spiked concentration levels of 0.05 %, 0.50 %, 0.10 % and 2.5 % with relative standard deviations (RSDs, n = 3) lower than 2.0 %. Finally, the developed methods were successfully applied to the quantitative analysis of minor components and used main components (leucomycin A3 and midecamycin A1) as alternative reference substance of minor components. The overall results demonstrated that the HPLC-CAD was a good alternative for the quantitative analysis of multi-components in 16-membered macrolides.

Bifunctional Nitrone-Conjugated Secondary Metabolite Targeting the Ribosome.

Many microorganisms possess the capacity for producing multiple antibiotic secondary metabolites. In a few notable cases, combinations of secondary metabolites produced by the same organism are used in important combination therapies for treatment of drug-resistant bacterial infections. However, examples of conjoined roles of bioactive metabolites produced by the same organism remain uncommon. During our genetic functional analysis of oxidase-encoding genes in the everninomicin producer Micromonospora carbonacea var. aurantiaca, we discovered previously uncharacterized antibiotics everninomicin N and O, comprised of an everninomicin fragment conjugated to the macrolide rosamicin via a rare nitrone moiety. These metabolites were determined to be hydrolysis products of everninomicin P, a nitrone-linked conjugate likely the result of nonenzymatic condensation of the rosamicin aldehyde and the octasaccharide everninomicin F, possessing a hydroxylamino sugar moiety. Rosamicin binds the erythromycin macrolide binding site approximately 60 Å from the orthosomycin binding site of everninomicins. However, while individual ribosomal binding sites for each functional half of everninomicin P are too distant for bidentate binding, ligand displacement studies demonstrated that everninomicin P competes with rosamicin for ribosomal binding. Chemical protection studies and structural analysis of everninomicin P revealed that everninomicin P occupies both the macrolide- and orthosomycin-binding sites on the 70S ribosome. Moreover, resistance mutations within each binding site were overcome by the inhibition of the opposite functional antibiotic moiety binding site. These data together demonstrate a strategy for coupling orthogonal antibiotic pharmacophores, a surprising tolerance for substantial covalent modification of each antibiotic, and a potential beneficial strategy to combat antibiotic resistance.

Characterization of 28 unknown impurities in 16-membered macrolides by liquid chromatography coupled with ion trap/time-of-flight mass spectrometry.

In terms of risk assessment, the study of the impurity profile is important to ensure the safety and effectiveness of drugs in clinical application. Sixteen-membered macrolides are produced by microbial fermentation, and many closely related substances in the product make the components and impurities complicated. In this study, methods were developed to separate and identify the impurities in three representative 16-membered macrolides (josamycin, midecamycin and meleumycin) using a high-performance liquid chromatography coupled to high-resolution ion trap/time-of-flight mass spectrometry (IT-TOF MS). In total, 53 impurities were characterized in the positive mode of electrospray ionization, among which 28 novel impurities were found. The proposed structures of impurities were deduced based on MS/MS data, and the ultraviolet (UV) absorption behaviors of impurities were discussed. In addition to the impurities with maximum absorption wavelengths (λmax) of 231 nm and 280 nm, there was a new group of impurities with λmax of 205 nm in meleumycin, midecamycin and josamycin.

Artificial control of the multistep oxidation reactions catalyzed by the cytochrome P450 enzyme RosC.

The cytochrome P450 monooxygenase RosC catalyzes the three-step oxidation reactions, which leads to the formation of a hydroxy, formyl, and carboxy group at C-20 during rosamicin biosynthesis in Micromonospora rosaria IFO13697. To determine if amino acid substitutions in RosC could allow for the control of the multistep oxidation reactions, we screened RosC random mutants. The RosC mutant RM30, with five amino acid substitutions (P107S, L176Q, S254N, V277A, and I319N), catalyzed only the first step of the oxidation reaction. Whole-cell assays using Escherichia coli cells expressing RosC mutants with single and double amino acid substitutions derived from RM30 indicated that P107S/L176Q, P107S/V277A, P107S/I319N, L176Q/V277A, L176Q/I319N, and S254N/V277A significantly reduced the catalytic activity of the second reaction, which is alcohol oxidation. Of the previously mentioned mutants, double mutants containing L176Q, which was presumed to occur in the FG loop region, lost the total catalytic activity of the third reaction (aldehyde oxidation). Additionally, an engineered M. rosaria strain with rosC disruption, which introduced the gene encoding the RosC mutants P107S/L176Q and P107S/V277A preferentially produced 20-dihydrorosamicin, which is formed after the first oxidation reaction of RosC.

Structure Elucidation of Macrolide Antibiotics Using MSn Analysis and Deuterium Labelling.

The 14- and 16-membered macrolide antibiotics are an important structural class. Ubiquitously produced by a number of bacterial strains, namely actinomycetes, purification and structure elucidation of the wide array of analogs is challenging, both for discovery efforts and methodologies to monitor for byproducts, metabolites, and contaminants. Collision-induced dissociation mass spectrometry offers an attractive solution, enabling characterization of mixtures, and providing a wealth of structural information. However, interpretation of these spectra can be difficult. We present a study of 14- and 16-membered macrolide antibiotics, including MSn analysis for unprecedented depth of coverage, and complimentary analysis with D2O and H218O labeling to elucidate fragmentation mechanisms. These analyses contrast the behaviors of varying classes of macrolides and highlight how analogues can be identified in relation to similar structures, which will provide utility for future studies of novel macrolides, as well as impurities, metabolites, and degradation products of pharmaceuticals. Graphical Abstract.

[Skin needle embedding for obese impaired glucose tolerance].

OBJECTIVE: To explore the effect difference between the skin needle embedding therapy and western medication for obese impaired glucose tolerance (IGT). METHODS: A total of 300 cases of obese IGT were assigned into an embedding group and a western medication group by random number table, 150 cases in each one. Standardized diagnosis and treatment programs were applied to reduce blood pressure, lipid, weight, and exercise and scientific diet management were used. 0.25 g oral deltamine was prescribed three times a day in the western medication group. Thumb-tack needle for subcutaneous embedding was at bilateral Weiwanxiashu (EX-B 3), Ganshu (BL 18), Pishu (BL 20), Tianshu (ST 25) and Zusanli (ST 36) for 36 to 48 hours on Monday and Thursday, 3 months as a session, with other acupoints differentiated. All the treatment was given for 2 years. The indexes included the blood sugar indexes [fasting plasma glucose (FPG), 2 h postprandial blood glucose (2 h PG), glycosylated hemoglobin (HbA1c)], incidence of hypoglycemia, obesity indexes [waist circumference, body mass index (BMI)], blood lipid indexes [serum total cholesterol (TC), serum triacylglycerol (TG), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C)], liver and kidney function indexes [serum creatinine (Scr), blood urea nitrogen (BUN) and blood uric acid (UA), glutamic-pyruvic transaminase (ALT)] and TCM symptom score. The effects and the incidence of type 2 diabetes were evaluated. RESULTS: After treatment, 2 h PG and HbA1c reduced in the two groups (P<0.01, P<0.05) and the results in the embedding group were better (both P<0.05). After treatment, the incidence of hypoglycemia in the embedding group was 0.7% (1/150), and that in the western medication group was 1.3% (2/150), without statistical difference (P>0.05). After treatment, waist circumference and BMI reduced in the two groups (both P<0.01) and the improvements in the embedding group were better (both P<0.05). TC, TG and LDL-C after treatment were lower than those before treatment, and HDL-C were higher in the two groups (all P<0.05), without statistical different values before and after treatment between the two groups (all P>0.05). Scr, BUN, UA and ALT before and after treatment in the two groups had no statistical difference (all P>0.05), without statistical difference after treatment between the two groups (all P>0.05). The TCM score after treatment was lower than that before treatment in the embedding group (P<0.05), and the difference was not statistical in the western medication group (P>0.05). The different value of TCM score in the embedding group was better than that in the western medication group (P<0.01). The total effective rate in the embedding group was 98.0% (147/150), which was superior to 92.7% (139/150) in the western medication group (P<0.05). The incidence of type 2 diabetes was 2.0% (3/150) in the embedding group, and that was better than 7.3% (11/150) in the western medication group (P<0.05). CONCLUSION: Thumb-tack needle for subcutaneous embedding for 2 years could apparent improve the indexes of IGT, which is better than western medication, without liver and kidney damage.

Macrolides for treatment of Haemophilus ducreyi infection in sexually active adults.

BACKGROUND: Chancroid is a genital ulcerative disease caused by Haemophilus ducreyi. This microorganism is endemic in Africa, where it can cause up to 10% of genital ulcers. Macrolides may be an effective alternative to treat chancroid and, based on their oral administration and duration of therapy, could be considered as first line therapy. OBJECTIVES: To assess the effectiveness and safety of macrolides for treatment of H ducreyi infection in sexually active adults. SEARCH METHODS: We searched the Cochrane STI Group Specialized Register, CENTRAL, MEDLINE, Embase, LILACS, WHO ICTRP, ClinicalTrials.gov and Web of Science to 30 October 2017. We also handsearched conference proceedings and reference lists of retrieved studies. SELECTION CRITERIA: Randomized controlled trials (RCTs) comparing macrolides in different regimens or with other therapeutic alternatives for chancroid. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trials for inclusion, extracted data and assessed risk of bias. We resolved disagreements through consensus. We used the GRADE approach to assess the quality of the evidence. MAIN RESULTS: Seven RCTs (875 participants) met our inclusion criteria, of which four were funded by industry. Five studies (664 participants) compared macrolides with ceftriaxone, ciprofloxacin, spectinomycin or thiamphenicol. Low quality evidence suggested there was no difference between the groups after treatment in terms of clinical cure (risk ratio (RR) 1.09, 95% confidence interval (CI) 0.97 to 1.21; 2 studies, 340 participants with syndromic approach and RR 1.06, 95% CI 0.98 to 1.15; 5 studies, 348 participants with aetiological diagnosis) or improvement (RR 0.89, 95% CI 0.52 to 1.52; 2 studies, 340 participants with syndromic approach and RR 0.80, 95% CI 0.42 to 1.51; 3 studies, 187 participants with aetiological diagnosis). Based on low and very low quality evidence, there was no difference between macrolides and any other antibiotic treatments for microbiological cure (RR 0.93, 95% CI 0.74 to 1.16; 1 study, 45 participants) and minor adverse effects (RR 1.34, 95% CI 0.24 to 7.51; 3 studies, 412 participants).Two trials (269 participants) compared erythromycin with any other macrolide type. Low quality evidence suggested that, compared with azithromycin or rosaramicin, long courses of erythromycin did not increase clinical cure (RR 1.00, 95% CI 0.91 to 1.10; 2 studies, 269 participants with syndromic approach and RR 1.04, 95% CI 0.93 to 1.16; 2 studies, 211 participants with aetiological diagnosis), with a similar frequency of minor adverse effects between the groups (RR 1.14, 95% CI 0.63 to 2.06; 1 trial, 101 participants). For this comparison, subgroup analysis found no difference between HIV-positive participants (RR 1.02, 95% CI 0.73 to 1.43; 1 study, 38 participants) and HIV-negative participants (RR 1.04, 95% CI 0.94 to 1.14; 1 study, 89 participants). We downgraded the quality of evidence to low, because of imprecision, some limitations on risk of bias and heterogeneity.None of the trials reported serious adverse events, cost effectiveness and participant satisfaction. AUTHORS' CONCLUSIONS: At present, the quality of the evidence on the effectiveness and safety of macrolides for treatment of H ducreyi infection in sexually active adults is low, implying that we are uncertain about the estimated treatment effect. There is no statistically significant difference between the available therapeutic alternatives for the treatment of sexually active adults with genital ulcers compatible with chancroid. Low quality evidence suggests that azithromycin could be considered as the first therapeutic alternative, based on their mono-dose oral administration, with a similar safety and effectiveness profile, when it is compared with long-term erythromycin use.Due to sparse available evidence about the safety and effectiveness of macrolides to treat H ducreyi infection in people with HIV, these results should be taken with caution.

5-O-Mycaminosyltylonolide antibacterial derivatives: design, synthesis and bioactivity.

Tylosin is a 16-membered macrolide broad-spectrum antibiotic that has an important role in veterinary medicine, active against Gram-positive and a restricted range of Gram-negative bacteria. We synthesized 15 types of tylosin-related derivatives by chemical modification and evaluated them against mastitis pathogens. Among them, 20-deoxy-20-{N-methyl-N-[1-(3-quinolyl)-1H-1,2,3-triazol-4-yl]methylamino}-5-O-mycaminosyltylonolide 2f and 20-deoxy-20-{N-benzyl-N-[1-(3-quinolyl)-1H-1,2,3-triazol-4-yl]methylamino}-5-O-mycaminosyltylonolide 2k were found to not only expand their antibacterial impact to include Gram-negative bacteria, such as Escherichia coli and Klebsiella pneumoniae, but also to retain or increase antibacterial activity against Gram-positive bacteria, such as Staphylococcus aureus and Streptococcus uberis in comparison with the parent tylosin.

Cytochrome P450 enzyme RosC catalyzes a multistep oxidation reaction to form the non-active compound 20-carboxyrosamicin.

The cytochrome P450 enzyme RosC catalyzes a two-step, hydroxylation and alcohol oxidation, oxidation reaction to form the C-20 formyl group in the biosynthesis of a 16-membered macrolide antibiotic rosamicin produced by Micromonospora rosaria IFO13697. RosC is presumed to be involved in the formation of 20-carboxyrosamicin because it has been isolated from the culture broth of M. rosaria. Here, we confirmed that RosC has catalytic activity, with E. coli expressing RosC converting rosamicin into 20-carboxyrosamicin. Therefore, it was revealed that RosC is a multifunctional P450 that catalyzes a three-step oxidation reaction that leads to the formation of the hydroxyl group, formyl group and carboxyl group at C-20 on the macrolactone ring in the rosamicin biosynthetic pathway. Moreover, the cytochrome P450 enzyme TylI, which is involved in formation of the formyl group of a 16-membered macrolide antibiotic tylosin produced by Streptomyces fradiae ATCC 19609, also converted rosamicin into 20-carboxyrosamicin.

Identification of two regulatory genes involved in carbomycin biosynthesis in Streptomyces thermotolerans.

Carbomycins are 16-membered macrolide antibiotics produced by Streptomyces thermotolerans ATCC 11416T. To characterize gene cluster responsible for carbomycin biosynthesis, the draft genome sequences for strain ATCC 11416T were obtained, from which the partial carbomycin biosynthetic gene cluster was identified. This gene cluster was approximately 40 kb in length, and encoding 30 ORFs. Two putative transcriptional regulatory genes, acyB2 and cbmR, were inactivated by insertion of the apramycin resistance gene, and the resulting mutants were unable to produce carbomycin, thus confirming the involvement of two regulatory genes in carbomycin biosynthesis. Overexpression of acyB2 greatly improved the yield of carbomycin; however, overexpression of cbmR blocked carbomycin production. The qPCR analysis of the carbomycin biosynthetic genes in various mutants indicated that most genes were highly expressed in acyB2-overexpressing strains, but few expressed in cbmR-overexpressing strains. Furthermore, acyB2 co-expression with 4″-isovaleryltransferase gene (ist), resulted in efficient biotransformation of spiramycin into bitespiramycin in S. lividans TK24, whereas ist gene regulated by acyB2 and cbmR would cause the lower efficiency of spiramycin biotransformation. These results indicated that AcyB2 was a pathway-specific positive regulator of carbomycin biosynthesis. However, CbmR played a dual role in the carbomycin biosynthesis by acting as a positive regulator, and as a repressor at cbmR high expression levels.

Characterization of the Two Methylation Steps Involved in the Biosynthesis of Mycinose in Tylosin.

The S-adenosyl-l-methionine-dependent O-methyltransferases TylE and TylF catalyze the last two methylation reactions in the tylosin biosynthetic pathway of Streptomyces fradiae. It has long been known that the TylE-catalyzed C2‴-O-methylation of the 6-deoxy-d-allose bound to demethylmacrocin or demethyllactenocin precedes the TylF-catalyzed C3‴-O-methylation of the d-javose (C2‴-O-methylated 6-deoxy-d-allose) attached to macrocin or lactenocin. This study reveals the unexpected substrate promiscuity of TylE and TylF responsible for the biosynthesis of d-mycinose (C3‴-O-methylated d-javose) in tylosin through the identification of a new minor intermediate 2‴-O-demethyldesmycosin (2; 3‴-methyl-demethyllactenocin), which lacks a 2‴-O-methyl group on the mycinose moiety of desmycosin, along with 2‴-O-demethyltylosin (1; 3‴-methyl-demethylmacrocin) that was previously detected from the S. fradiae mutant containing a mutation in the tylE gene. These results unveil the unique substrate flexibility of TylE and TylF and demonstrate their potential for the engineered biosynthesis of novel glycosylated macrolide derivatives.

Salinipyrone and Pacificanone Are Biosynthetic By-products of the Rosamicin Polyketide Synthase.

Salinipyrones and pacificanones are structurally related polyketides from Salinispora pacifica CNS-237 that are proposed to arise from the same modular polyketide synthase (PKS) assembly line. Genome sequencing revealed a large macrolide PKS gene cluster that codes for the biosynthesis of rosamicin A and a series of new macrolide antibiotics. Mutagenesis experiments unexpectedly correlated salinipyrone and pacificanone biosynthesis to the rosamicin octamodule Spr PKS. Remarkably, this bifurcated polyketide pathway illuminates a series of enzymatic domain- and module-skipping reactions that give rise to natural polyketide product diversity. Our findings enlarge the growing knowledge of polyketide biochemistry and illuminate potential challenges in PKS bioengineering.

A new mycinosyl rosamicin derivative produced by an engineered Micromonospora rosaria mutant with a cytochrome P450 gene disruption introducing the D-mycinose biosynthetic gene.

Genetic engineering of post-polyketide synthase-tailoring genes can be used to generate new macrolide analogs through manipulation of the genes involved in their biosynthesis. Rosamicin, a 16-member macrolide antibiotic produced by Micromonospora rosaria IFO13697, contains a formyl group and an epoxide at C-20 and C-12/13 positions which are formed by the cytochrome P450 enzymes RosC and RosD, respectively. The D-mycinose biosynthesis genes in mycinamicin II biosynthesis gene cluster of Micomonospora guriseorubida A11725 were introduced into the rosC and rosD disruption mutants of M. rosaria IFO13697. The resulting engineered strains, M. rosaria TPMA0054 and TPMA0069, produced mycinosyl rosamicin derivatives, IZIV and IZV, respectively. IZIV was identified as a novel mycinosyl rosamicin derivative, 23-O-mycinosyl-20-deoxo-20-dihydrorosamicin.

Macrolides attenuate phorbol ester-induced tumor necrosis factor-α and mucin production from human airway epithelial cells.

BACKGROUND/AIMS: Macrolide antibiotics are effective drugs in chronic bronchiolitis and chronic rhinosinusitis with mucus hypersecretion. However, the mechanism of action is unclear. This study was designed to investigate the effect of azithromycin (AZM; 15-membered) and midecamycin acetate (MDM; 16-membered) on MUC5AC and MUC2 gene expression and secretion from human airway epithelial cells. The effects of the two macrolides on tumor necrosis factor-α (TNF-α) release were also examined. METHODS: Confluent NCI-H292 human mucoepidermoid airways epithelial cells were pretreated with AZM or MDM for 2 h and then stimulated with 200 nmol/l phorbol 12-myristate 13-acetate (PMA) for 8 h. The MUC5AC and MUC2 gene expression was measured by real-time quantitative RT-PCR. Total mucin in culture supernatants was measured using enzyme-linked lectin assay. Enzyme-linked immunosorbent assay was used to determine MUC5AC, MUC2 and TNF-α released by the cells. RESULTS: AZM and MDM attenuated PMA-induced MUC5AC and MUC2 gene and protein expression in NCI-H292 cells. They also suppressed PMA-mediated TNF-α in the cells. CONCLUSION: The present study demonstrates that AZM and MDM suppress the synthesis of mucin and TNF-α from human airway epithelial cells.

Biotransformation of rosamicin antibiotic into 10,11-dihydrorosamicin with enhanced in vitro antibacterial activity against MRSA.

A biotransformation approach using microbes as biocatalysts can be an efficient tool for the targeted modification of existing antibiotic chemical scaffolds to create previously uncharacterized therapeutic agents. By employing a recombinant Streptomyces venezuelae strain as a microbial catalyst, a reduced macrolide, 10,11-dihydrorosamicin, was created from rosamicin macrolide. Its chemical structure was spectroscopically elucidated, and the new rosamicin analog showed 2-4-fold higher antibacterial activity against two strains of methicillin-resistant Staphylococcus aureus compared with its parent rosamicin. This kind of biocatalytic approach is able to expand existing antibiotic entities and can also provide more diverse therapeutic resources.

Ion mobility spectrometry for the simultaneous determination of diacetyl midecamycin and detergents in cleaning validation.

In the present paper, we have developed two different approaches based on ion mobility spectrometry (IMS) for the cleaning validation of diacetyl midecamycin in the surfaces of manufacture equipment: a semi-quantitative approach based on the use of a sample wand and a quantitative procedure based on the swab test. The simultaneous determination of the active pharmaceutical ingredient and cleaning agents has been performed without important effects of ionization suppression upon the analysis of swabs containing multiple components. Sensitivity, in the ng range, and appropriate selectivity ratify IMS as a serious alternative, a fast and serious alternative in cleaning validation. Other advantage imply its potential for at-line use to perform a semi-quantitative procedure using a sample wand which allows Teflon membranes, swabbed onto the stainless steel surfaces, to be introduced directly into the instrument with no dilution or extraction.