Chloramphenicol Base Research Articles

Non-targeted screening and toxicity study of safety risk substances in facial skincare products: Molecular networking and computational toxicology strategy

BackgroundRisk substances in cosmetics have long been associated with adverse reactions. However, as risk substances become more concealed and diversified, conventional targeted analysis methods are no longer sufficient to meet regulatory requirements. ObjectiveTo construct a rapid and effective non-targeted screening method for the identification of risk substances, and to provide a high-throughput method for toxicity assessment. MethodsMolecular networking was utilized for the non-targeted screening of risk substances in facial skincare products, and the toxicity of these risk substances was evaluated through molecular docking and quantitative structure-activity relationship (QSAR) models. ResultsThrough molecular networking, we identified seven known prohibited ingredients, six of which were confirmed using standard substances. In addition, 17 potential risk substances were discovered within molecular clusters containing prohibited ingredients, including antibiotics, antihistamines, and phthalates, etc. Notably, chloramphenicol base and N-desmethyl chlorpheniramine exhibited stronger binding affinity to keratin 5/14 than chloramphenicol and chlorpheniramine through molecular docking, respectively. Additionally, toxicity prediction results indicated that the carcinogenicity of antibiotics presented gender differences in mice and rats, and two chlorpheniramine derivatives also showed carcinogenicity in mice. Moreover, of the 24 compounds, 11 showed skin sensitization, while 14 caused skin irritation. Furthermore, half of these compounds demonstrated potential developmental toxicity, and only 4-nitrobenzenethiol was found to be mutagenic. ConclusionIn this study, we developed a visualization strategy for non-targeted screening of risk substances and a high-throughput method for initial toxicity assessment of risk substances.

Novel porous organic polymer supported chloramphenicol base derivatives: A highly enantioselective, recyclable heterogeneous organocatalyst for asymmetric desymmetrization reaction

A series of porous organic polymer (POP) supported chloramphenicol base (ANP) derived catalysts are designed and prepared. A deep study of the polymerization condition, including reaction temperature, the ratio of monomers and the option of polymetric position on ANP scaffold was conducted. The best catalyst, poly-Ia, performs high stereoselectivity and catalytic activity (up to 98% yield and 99% ee) in asymmetric alcoholysis of meso-cyclic anhydride with the possibility of high recyclability (at least 10 times). More importantly, poly-Ia even obtains higher enantioselectivity compared to its homogeneous monomer, which overcomes the common drawback of heterogeneous organocatalysts, for instance, lower selectivity and diminished reactivity.

Novel hapten design, highly sensitive monoclonal antibody production, and immunoassay development for rapid screening of illegally added chloramphenicol in cosmetics

Hapten design and synthesis have been regarded as the key factor to generate high-quality antibodies. In the present study, a novel hapten of chloramphenicol was synthesized, characterized and compared with two conventional haptens. The new hapten generated mAb 4B5 showed higher sensitivity and titer than the other two haptens-based mAbs. The haptens synthesized with the structure of chloramphenicol base generated more sensitive antibodies than the hapten with chloramphenicol succinate, and the spacer arm linked to the phenyl group hapten elicited the strongest antibody response. After optimization, a direct competitive enzyme-linked immunosorbent assay (dcELISA) and a lateral flow immunoassay (LFIA), both based on the mAb 4B5, were developed. The dcELISA had a half maximum inhibition concentration of 0.23 ng/mL and the LFIA showed a cutoff value of 5–10 ng/mL. The LFIA was applied to detect illegally-added chloramphenicol samples in anti-acne cosmetics, five out of 19 samples were tested chloramphenicol containing within 10 min, which result was confirmed with the dcELISA and HPLC. The LFIA has an adequate sensitivity and can be used as a point of care diagnostic device for rapidly screening chloramphenicol in cosmetics.

Research on promoting the asymmetric reaction of phenylacetylene with aldehydes by chloramphenicol base ligands.

A series of chiral ligands were synthesized using chloramphenicol base as starting materials. These ligands were applied to the asymmetric catalytic reactions of terminal alkynes with aldehydes to obtain a propargyl alcohol product in high yield (80-94%) with excellent enantioselectivities (82-96%).

Optical Resolution of Two Pharmaceutical Bases with Various Uses of Tartaric Acid Derivatives and Their Sodium Salts: Racemic Ephedrine and Chloramphenicol Base.

The optically active dibenzoyltartaric acid, tartaric acid, and its sodium salts were successfully applied to the optical resolution of (1R,2S)(1S,2R)-2-(methylamino)-1-phenylpropan-1-ol (EPH) and (1R,2R)(1S,2S)-2-amino-1-(4-nitrophenyl)propane-1,3-diol (AD) as resolving agents. It was observed that both compounds’ resolution using a mixture of salts of quasi-racemic resolving agents showed a change in chiral recognition under the same conditions compared to the result of the use of the single enantiomeric resolving agent. The changes are followed by detailed analytical (XRD, FTIR, and DSC) studies. Meanwhile, the DASH indexing software package was also tested on powder XRD patterns of pure initial materials and intermediate salt samples of high diastereomeric excess.

Copper-catalyzed asymmetric alkynylation of pyrazole-4,5-diones using chloramphenicol base-derived hydroxyl oxazoline ligands

The asymmetric copper-catalyzed alkynylations of pyrazole 4,5-diones using a chloramphenicol base derived hydroxyl oxazoline ligand are reported. Diverse enantioenriched propargyl alcohols were obtained in good to excellent yields and ee's.

New Chloramphenicol Derivatives with a Modified Dichloroacetyl Tail as Potential Antimicrobial Agents.

To combat the dangerously increasing pathogenic resistance to antibiotics, we developed new pharmacophores by chemically modifying a known antibiotic, which remains to this day the most familiar and productive way for novel antibiotic development. We used as a starting material the chloramphenicol base, which is the free amine group counterpart of the known chloramphenicol molecule antibiotic upon removal of its dichloroacetyl tail. To this free amine group, we tethered alpha- and beta-amino acids, mainly glycine, lysine, histidine, ornithine and/or beta-alanine. Furthermore, we introduced additional modifications to the newly incorporated amine groups either with protecting groups triphenylmethyl- (Trt) and tert-butoxycarbonyl- (Boc) or with the dichloroacetic group found also in the chloramphenicol molecule. The antimicrobial activity of all compounds was tested both in vivo and in vitro, and according to the results, the bis-dichloroacetyl derivative of ornithine displayed the highest antimicrobial activity both in vivo and in vitro and seems to be a dynamic new pharmacophore with room for further modification and development.

Pharmacokinetics of multiple doses of chloramphenicol in fed adult horses

To the authors’ knowledge, there have been no studies evaluating the pharmacokinetics of chloramphenicol administered orally to horses at the currently recommended dose of 50 mg/kg PO q6 h for multiple days. The published antimicrobial susceptibility breakpoint is 8.0 ug/mL; it is unknown if this concentration is achievable at the recommended dose rate in horses. The aim of this prospective multi-dose pharmacokinetic study was to perform pharmacokinetic analysis of chloramphenicol after multiple doses. The authors hypothesize that the antimicrobial susceptibility breakpoint will not be reached. Seven healthy adult horses were administered 50 mg/kg chloramphenicol base tablets PO q6 h for 4 days. Blood was collected via venipuncture daily at 4 and 6 h after administration for the first 15 doses. After the 16th dose, an IV catheter was aseptically placed in the right jugular vein and blood was collected at regular intervals for pharmacokinetic analysis.Maximum chloramphenicol concentration was variable between horses (2.1–42.7 μg/mL). The highest average chloramphenicol concentration was just below the susceptibility breakpoint at 7.7 ug/mL while the lowest was well below the breakpoint at 1.5 ug/mL. On average, the time above 8.0 μg/mL was 75 min, considerably less than the recommended 50% of the dosing interval. When chloramphenicol is administered at a dose of 50 mg/kg PO q6 h in horses, the highest reliably achievable steady state concentration for at least half of the dosing interval is 2.0 μg/mL. The established susceptibility breakpoint of 8.0 ug/mL is not achievable in adult horses, and should be re-evaluated.

Prima Krim sebagai Solusi Penyembuh Luka pada Penderita Diabetes Meli

Number of patients with diabetes mellitus are very large, according to International Diabetes Federation (IDF) in 2013 reaches 382 billion people between the ages of 40-59 years. Diabetic has been characterized as a chronic wounds. The animal blood waste from a slaugther house is still untapped, containing PRP (Platelet Rich Plasma) that can accelerates heal of bone and soft tissue. PRP (Platelet Rich Plasma) was made from the cattle blood waste using centrifugation. The purpose of the study is to prove that the Prima cream can heal the wounds in diabetic patients. Animals used in this study is 20 Wistar rats. Induction of diabetes was using streptozootocin 65 mg/kg and nicotinamide 235 mg/kg. The animal were divided into 4 groups: non-diabetes given placebo (ND-), diabetes given placebo (DM-), diabetic rat given commercial drug were containing chloramphenicol base 20 mg + prednisolone 2.5 mg (DM+), and diabetes given cream PRP at 20% concentration (DM PRP). Parameters used to measure the rate of wound healing is wound size and histopathologic examination. The data were analyzed using Anova One Way at 95% significant rate. PRP DM group had a wound healing faster than ND- group, DM- and DM+. Based on histopathologic examination, such as epitelialization, basal membrane, fibroblasts, collagen tissue, and presence of inflammatory cells, the best curing reaction was showed in DM PRP. PRP 20% cream produces from cow blood waste can accelerate wound healing in diabetes mellitus.

Cover Feature: Chloramphenicol Base: A New Privileged Chiral Scaffold in Asymmetric Catalysis (ChemCatChem 8/2019)

Cover Feature: Chloramphenicol Base: A New Privileged Chiral Scaffold in Asymmetric Catalysis (ChemCatChem 8/2019)

Chloramphenicol Base: A New Privileged Chiral Scaffold in Asymmetric Catalysis

AbstractThis Minireview focuses on the synthetic application of a chloramphenicol base (ANP)‐derived catalyst. In the illustrated examples, ANP derivatives have proven to be readily available and highly versatile catalysts in a wide range of asymmetric transformations, showing high proficiency as both chiral ligands (amino alcohol, Schiff base and oxazoline‐containing ligand) and organocatalyst (hydrogen bonding‐based bifunctional catalyst and phase transfer catalyst).

New Chloramphenicol Derivatives from the Viewpoint of Anticancer and Antimicrobial Activity.

Over the last years, we have been focused on chloramphenicol conjugates that combine in their structure chloramphenicol base with natural polyamines, spermine, spermidine and putrescine, and their modifications. Conjugate 3, with spermidine (SPD) as a natural polyamine linked to chloramphenicol base, showed the best antibacterial and anticancer properties. Using 3 as a prototype, we here explored the influence of the antibacterial and anticancer activity of additional benzyl groups on N1 amino moiety together with modifications of the alkyl length of the aminobutyl fragment of SPD. Our data demonstrate that the novel modifications did not further improve the antibacterial activity of the prototype. However, one of the novel conjugates (4) showed anticancer activity without affecting bacterial growth, thus emerging as a promising anticancer agent, with no adverse effects on bacterial microflora when taken orally.

Synthesis of modified β-methoxyphenylalanines via diazonium chemistry and their incorporation in desoxycyclomarin analogues.

The marine natural products cyclomarins have remarkable anti-mycobacterial and antiplasmodial activities. The heptapeptic structure of this compound class comprisis four highly interesting non-canonical amino acids, including a rather unusual syn β-methoxyphenylalanine. To get a deeper insight into the structure-activity realtionship of cyclomarines, a straightforward protocol for the stereoselective synthesis of this building block was developed, based on diazonium chemistry.

Squaramide‐Linked Chloramphenicol Base Hybrid Catalysts for the Asymmetric Michael Addition of 2,3‐Dihydrobenzofuran‐2‐carboxylates to Nitroolefins

An array of hybrid catalysts incorporating a chloramphenicol base moiety linked to another chiral scaffold through a squaramide linker were developed and successfully used in the Michael addition of 2,3‐dihydrobenzofuran‐2‐carboxylates to nitroolefins. Control experiments suggested that the hybrid catalysts were more reactive than nonhybridized bifunctional catalysts, and matching of the chirality between the two scaffolds was crucial for high reactivity and stereoselectivity. These hybrid organocatalysts could be used with a variety of substrates. At a 0.5 mol‐% catalyst loading, a range of 2,3‐dihydrobenzofuran‐2‐carboxylates derivatives bearing quaternary and tertiary stereogenic centers were obtained in high yields (up to 98 %) with excellent enantioselectivities (up to 99 % ee) and moderate diastereoselectivities (up to 8:92 dr).

In this issue – September 2017

In this issue – September 2017

Pharmacokinetics of chloramphenicol base after oral administration in adult horses.

OBJECTIVE To determine the pharmacokinetics of chloramphenicol base after PO administration at a dose of SO mg/kg (22.7 mg/lb) in adult horses from which food was not withheld. DESIGN Prospective crossover study. ANIMALS 5 adult mares. PROCEDURES Chloramphenicol base (SO mg/kg) was administered PO to each horse, and blood samples were collected prior to administration (0 minutes) and at 5, 10, 15, and 30 minutes and 1, 2, 4, 8, and 12 hours thereafter. Following a washout period, chloramphenicol sodium succinate (25 mg/kg [11.4 mg/lb]) was administered IV to each horse, and blood samples were collected prior to administration (0 minutes) and at 3, 5, 10, 15, 30, and 45 minutes and 1, 2, 4, and 8 hours thereafter. RESULTS In horses, plasma half-life, volume of distribution at steady state, clearance, and area under the plasma concentration-time curve for chloramphenicol after IV administration ranged from 0.65 to 1.20 hours, 0.51 to 0.78 L/kg, 0.78 to 1.22 L/h/kg, and 20.5 to 32.1 h·μg/mL, respectively. The elimination half-life, time to maximum plasma concentration, maximum plasma concentration, and area under the plasma concentration-time curve after PO administration ranged from 1.7 to 7.4 hours, 0.25 to 2.00 hours, 1.52 to 5.45 μg/mL, and 10.3 to 21.6 h·μg/mL, respectively. Mean ± SD chloramphenicol bioavailability was 28 ± 10% and terminal half-life was 2.85 ± 1.32 hours following PO administration. CONCLUSIONS AND CLINICAL RELEVANCE Given that the maximum plasma chloramphenicol concentration in this study was lower than previously reported values, it is recommended to determine the drug's MIC for target bacteria before administration of chloramphenicol in adult horses.

Chloramphenicol base chemistry. Part 11: chloramphenicol base-derived thiourea-catalyzed enantioselective Michael addition of malononitrile to α,β-unsaturated ketones

The first chloramphenicol base-derived thiourea-catalyzed enantioselective Michael addition of malononitrile to α,β-unsaturated ketones is reported. The Michael adducts were obtained in good to excellent yields (up to 98% yield) and enantioselectivities (up to 94% ee). This reaction has a broad substrate scope to various α,β-unsaturated ketones. With this in mind, this methodology was successfully applied to the synthesis of a chiral piperidone, an advanced building block for dihydropyridinone P2X7 receptor antagonists.

Chloramphenicol base chemistry. Part 10 : Asymmetric synthesis of α-hydroxy chiral alcohols via intramolecular Michael additions of γ-hydroxy-α, β-unsaturated enones with chloramphenicol base derived bifunctional urea organocatalysts

We have developed the chloramphenicol base urea-catalyzed intramolecular Michael addition of γ-hydroxy-α, β-unsaturated enones. The oxidation of the resulting products provided facile access to the corresponding α-hydroxy chiral alcohols with good efficiency and enantioselectivity, with the reaction displaying broad substrate scope. The utility of this methodology was further demonstrated by the synthesis of (R)-2-hydroxy-4-phenylbutanoate, which is a key building block for the construction of the ACE inhibitor benazepril hydrochloride.

Discovery and characterization of a new hydroxynitrile lyase

A robust and practical method has been developed for the synthesis of florfenicol (1) starting from commercial available 4-(methylsulfonyl) benzoic acid. The key step in this synthesis was the Ru-chloramphenicol base catalyzed asymmetric transfer hydrogenation of N-Boc α-amino-β-ketoester 5 through a dynamic kinetic resolution, which afforded the key chiral building block, anti-(2S,3S)-α-Boc-amino-β-hydroxyl ester 4, with high diastereoselectivity (92% de) and enantioselectivity (78% ee). The synthesis of a series of novel chloramphenicol base ligands L1–L10 is also included. This protocol could also be used for the asymmetric synthesis of fully synthetic analogs of florfenicol.

Development of Bifunctional Thiourea Organocatalysts Derived from a Chloramphenicol Base Scaffold and their Use in the Enantioselective Alcoholysis of meso Cyclic Anhydrides

AbstractThe synthesis of new chloramphenicol‐base‐derived thiourea organocatalysts, (1S,2R)‐12 a–f and (1R,2R)‐15 a–c, and their use in the enantioselective alcoholysis of meso‐anhydrides are described. In particular, hemiesters afforded excellent enantioselectivities if low loadings of (1S,2R)‐12 a–f were used. Almost no enantioselectivities were achieved with the use of (1R,2R)‐15 a–c. This technique was used to synthesize (R)‐(−)‐baclofen.