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The incidence of Mycobacterium marinum infection is on the rise; however, the existing drug treatment cycle is lengthy and often requires multi-drug combination. Therefore, there is a need to develop new and effective anti-M. marinum drugs. Cochliomycin A, a 14-membered resorcylic acid lactone with an acetonide group at C-5′ and C-6′, exhibits a wide range of antimicrobial, antimalarial, and antifouling activities. To further explore the effect of this structural change at C-5′ and C-6′ on this compound’s activity, we synthesized a series of compounds with a structure similar to that of cochliomycin A, bearing ketal groups at C-5′ and C-6′. The R/S configuration of the diastereoisomer at C-13′ was further determined through an NOE correlation analysis of CH3 or CH2 at the derivative C-13′ position and the H-5′ and H-6′ by means of a 1D NOE experiment. Further comparative 1H NMR analysis of diastereoisomers showed the difference in the chemical shift (δ) value of the diastereoisomers. The synthetic compounds were screened for their anti-microbial activities in vitro. Compounds 15–24 and 28–35 demonstrated promising activity against M. marinum, with MIC90 values ranging from 70 to 90 μM, closely approaching the MIC90 of isoniazid. The preliminary structure–activity relationships showed that the ketal groups with aromatic rings at C-5′ and C-6′ could enhance the inhibition of M. marinum. Further study demonstrated that compounds 23, 24, 29, and 30 had significant inhibitory effects on M. marinum and addictive effects with isoniazid and rifampicin. Its effective properties make it an important clue for future drug development toward combatting M. marinum resistance.

Here, we report on the construction of biodegradable poly(ethylene oxide monomethyl ether) (MPEO)-b-poly(ε-caprolactone) (PCL) nanoparticles (NPs) having acid-labile (acyclic ketal group) linkage at the block junction. In the presence of acidic pH, the nanoassemblies were destabilized as a consequence of cleaving this linkage. The amphiphilic MPEO-b-PCL diblock copolymer self-assembled in PBS solution into regular spherical NPs. The structure of self-assemble and disassemble NPs were characterized in detail by dynamic (DLS), static (SLS) light scattering, small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). The key of the obtained NPs is using them in a paclitaxel (PTX) delivery system and study their in vitro cytostatic activity in a cancer cell model. The acid-labile ketal linker enabled the disassembly of the NPs in a buffer simulating an acidic environment in endosomal (pH ~5.0 to ~6.0) and lysosomal (pH ~4.0 to ~5.0) cell compartments resulting in the release of paclitaxel (PTX) and formation of neutral degradation products. The in vitro cytotoxicity studies showed that the activity of the drug-loaded NPs was increased compared to the free PTX. The ability of the NPs to release the drug at the endosomal pH with concomitant high cytotoxicity makes them suitable candidates as a drug delivery system for cancer therapy.

A benchmarking study is reported on a series of modified carbocatalysts to efficiently promote the acetalization of 1,2-diols under heterogeneous conditions. Among the catalysts surveyed, a hydrothermal carbon generated from saccharose, a cheap, abundant, and biobased material, showed excellent performance when tested on two representative diols. All catalysts have been thoroughly characterized, focusing on surface acidity and composition. Optimal working parameters such as temperature and catalyst loading could be established. Remarkably, sonication improved the diol protection, which proceeded faster at 25 °C. The catalyst could be easily recycled and reused several times. In addition, the protocol was successfully translated from batch to continuous flow operation using a packed-bed reactor.

The Michael adducts of levoglucosenone and cyclohexanone were used to develop a rapid synthesis of nonano-9-lactones fused to a pyran ring containing a pharmacophoric dichloromethylene substituent. The key step in the synthesis is a cleavage, under the action of pyridinium chlorochromate, of the bridge in the hexahydrochroman formed by the etherification of the keto function by the hydroxyl group in the 1,6-anhydro bridge, which accompanies the cleavage the latter bridge in the levoglucosenone–cyclohexanone Michael adduct. It was established that the presence of the dichloromethylene substituent in the pyran ring does not significantly affect the cleavage of the hexahydrochroman bridge.

With the goal of obtaining fused dilactones, the carbohydrate moiety of diastereoisomeric Michael adducts of levoglucosenone and cyclohexanone was converted to δ-lactone and its derivatives fused to an octahydrochromene fragment. The subsequent oxidative cleavage of the C-C bridge in the latter by the action of pyridiniun chlorochromate (PCC) afforded nonano-9-lactone fused at the C 6 -C 7 bond to δ-lactone or methyl-δ-lactol. The presence of a carbonyl group in the carbohydrate moiety was found to prevent C-C bond cleavage.

This opinion considers the safety and efficacy of 29 compounds belonging to chemical group 8. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) established the following conclusions: menthol [02.015] is safe at 25 mg/kg complete feed for all target species; menthyl acetate [09.016], d‐carvone [07.146] and methyl dihydrojasmonate [09.520] at 5 mg/kg for all species; α‐ionone [07.007], β‐ionone [07.008] and d,l‐isoborneol [02.059] at 5 mg/kg feed for salmonids, veal calves and dogs, and at 1 mg/kg feed for the remaining species; d,l‐isobornyl acetate [09.218] at 5 mg/kg for all target species except chickens for fattening, laying hens, piglets and cats, for which 1 mg/kg is safe; d,l‐borneol [02.016], fenchyl alcohol [02.038], α‐irone [07.011], (Z)‐β‐damascone [07.083], β‐damascenone [07.108], (E)‐β‐damascone [07.224], cyclohexyl acetate [09.027], carvyl acetate [09.215], dihydrocarvyl acetate [09.216] and fenchyl acetate [09.269] at 1 mg/kg for all target species; and d,l‐isomenthone [07.078], nootkatone [07.089], Z‐jasmone [07.094], 3‐methyl‐2‐cyclopenten‐1‐one [07.112], isophorone [07.126], dihydrojasmone [07.140], l‐carvone [07.147], d‐fenchone [07.159], trans‐menthone [07.176], d‐camphor[07.215] and d,l‐bornyl acetate [09.017] are safe only at concentrations below the proposed use levels (0.5 mg/kg for cattle, salmonids and non‐food producing animals, and 0.3 mg/kg for pigs and poultry). No safety concern would arise for consumers from the use of these compounds as proposed in feeds. Hazards for skin and eye contact, and respiratory exposure are recognised for the majority of the compounds under application. Most are classified as irritating to the respiratory system. Use of the majority of the compounds in animal feed at the maximum safe level is considered safe for the environment. As all of the compounds are used in food as flavourings and their function in feed is essentially the same as that in food no demonstration of efficacy is necessary.

During a synthetic sequence, a carbonyl group may have to be protected against attack by various reagents such as strong or moderately strong nucleophiles, including organometallic reagents; acidic, basic, catalytic, or hydride reducing agents; and some oxidants. Cyclic and acyclic acetals and ketals are stable to aqueous and nonaqueous bases, to nucleophiles including organometallic reagents, and to hydride reduction. The carbonyl group forms a number of other very stable derivatives. Such derivatives include cyanohydrins, hydrazones, imines, oximes, and semicarbazones. Although IUPAC no longer uses the term ketal, it has retained it to indicate compounds formed from ketones. This chapter describes the derivatives of carbonyl compounds that have been used as protective groups in synthetic schemes. Acyclic monothio acetals and ketals can be prepared directly from a carbonyl compound or by transketalization, a reaction that does not involve a free carbonyl group, from a 1,3‐dithiane or 1,3‐dithiolane.

Makanan merupakan keperluan asas manusia yang sangat penting untuk pertumbuhan fizikal dan perkembangan minda. Oleh itu, kajian ini bertujuan membincangkan faktor yang menyumbang kepada keterancaman sekuriti makanan komuniti Lanoh daripada aspek ketersediaan makanan, kebolehcapaian makanan, penggunaan makanan dan kestabilan bekalan makanan. Kajian dilakukan menggunakan kaedah kaji selidik dan temu bual. Sebanyak 47 orang responden terlibat dengan soal selidik dan temu bual secara mendalam melibatkan 10 orang responden. Hasil analisis menunjukkan bahawa realitinya komuniti Lanoh sedang berhadapan dengan ancaman sekuriti makanan yang boleh memberi kesan kepada kesihatan mereka. Selain itu, faktor kebolehcapaian makanan yang terhad seperti pendapatan yang rendah, ketiadaan pemilikan kenderaan, tiada kemudahan pengangkutan awam disediakan dan keadaan jalan yang kurang memuaskan telah mengehadkan keupayaan mereka untuk mendapatkan makanan. Dari aspek pemakanan menunjukkan komuniti ini mengamalkan diet pemakanan yang kurang sihat dan seimbang iaitu kurang pengambilan makanan berunsurkan protein dan produk tenusu yang baik untuk pertumbuhan dan kesihatan. Akhirnya, pembalakan menyebabkan berlakunya kemusnahan kepada sumber hutan dan memberi ancaman kepada kestabilan bekalan makanan penduduk pada masa hadapan. Oleh itu, faktor kurangnya ketersediaan dan kebolehcapaian kepada makanan yang sihat dan mencukupi, amalan diet pemakanan yang tidak seimbang dan berlakunya ketidakstabilan bekalan makanan merupakan faktor ancaman berlakunya sekuriti makanan kepada komuniti Lanoh yang boleh memberi kesan kepada kesihatan mereka.