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The extensive use of antibiotics in the medical and aquaculture industries has led to antibiotic resistance, be a global public health concern. Compared with soil and water, there are few reports on antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the air. To provide theoretical support for scientific and effective response to the cross-media migration of microbial resistance, this paper comprehensively reviewed the occurrence status, influencing factors and transmission mechanism of ARB and ARGs in different types of ambient air at home and abroad. The results showed that the abundance of ARB and ARGs in the air was affected by environmental conditions and sampling factors. The pollution was more serious in typical polluted areas such as animal farms, sewage treatment plants and hospitals. The dominant types of ARGs in the above environment were tetracyclines, sulfonamides and β-lactams. Among them, the abundance of ARGs in the air of animal farms was about 2-3 orders of magnitude higher than that in other environments. The highest abundance was found in pig farm compared to other animal houses. At present, there was still no standard for the sampling requirements of ARB and ARGs in the air. The sampling season, duration, particle size and coexisting pollutants all affected their detection. Air pollution, soil water content, rainfall and air mass movement were proved to play a certain role in affecting the spread of ARB and ARGs in the air. Based on it, the research on the migration mechanism of ARB and ARGs at the soil-air interface needs to be further intensified. The review aimed to comprehensively reveal the occurrence characteristics of ARB and ARGs in the air, and provide theoretical support for the scientific and effective response to the cross-media migration of microbial resistance. [ABSTRACT FROM AUTHOR]

Glycyrrhetinic acid (GA) had been the star anticancer lead compound and appealed to many scientists all over the world; however, its antitumor activity was not potent enough. To improve GA's cytoxicity and explore the effect of bonding mode on antitumor activity, 32 compounds including GA-OH series (GO, esters in C-3 position) and GA-NH 2 series (GN, with amide linkages in C-3 position) had been designed and synthesized. All the compounds were screened for in vitro cytotoxicity against A549, HepG2, MCF-7, Hela and MDCK cell lines. As a result, all the de-protected (without Boc group) derivatives showed much stronger cytotoxic activity than GA, and surprisingly enough, all the GN series of the compounds were more potent than GO series against various tumor cells. Among them, the compound 26 (amide linkages in C-3 position) exhibited stronger antitumor activity against A549 cell line (IC 50 = 2.109 ± 0.11 μM) than the positive drug cisplatin (IC 50 = 9.001 ± 0.37 μM). Further studies indicated that compound 26 could induce A549 apoptosis via nuclei fragmentation. The detection of apoptosis and cell cycle analysis indicated that compound 26 could induce the early apoptosis and prevent A549 cells transition from S to G2 phase. Furthermore, the structure-activity relationships were briefly discussed. Among which, current study displayed amide linkages in C-3 position could effectively enhance GA cytotoxicity, providing a new modification strategy for further study. Image 1 • Thirty-two glycyrrhetinic acid (GA) derivatives had been designed and synthesized. • Most of the compounds were more potent than GA and positive drug cisplatin. • All the GN series were more potent than GO series against various tumor cells. • Compound 26 showed the most potent antitumor activity among all derivatives. [ABSTRACT FROM AUTHOR]

Clinical applications of camptothecin (CPT) have been heavily hindered due to its non-targeted toxicity, active lactone ring instability, and poor water solubility. Targeted drug delivery systems may offer the possibility to overcome the above issues as reported. In this research, a series of prostate-specific membrane antigen (PSMA)-activated CPT prodrugs were designed and synthesized by coupling water-soluble pentapeptide, a PSMA hydrolyzing substrate, to CPT through an appropriate linker. The cytotoxicity of CPT prodrugs was masked temporarily until they were hydrolyzed by the PSMA present within the tumor sites, which restored cytotoxicity. The in vitro selective cytotoxic activities of the prodrugs were evaluated against PSMA-expressing human prostate cancer cells LNCaP-FGC and non-PSMA-expressing cancer cells HepG2, Hela, MCF-7, DU145, PC-3 and normal cells MDCK, LO2 by standard methylthiazol tetrazolium (MTT) assay. Most of the newly synthesized CPT prodrugs showed excellent selective toxicity to PSMA-producing prostate cancer cells LNCaP-FGC with improved water solubility. From among the library, CPT-HT-J-ZL12 showed the best cytotoxic selectivity between the PSMA-expressing and the non-PSMA-expressing cancer cells. For example, the cytotoxicity of CPT-HT-J-ZL12 (IC50 = 1.00 ± 0.20 µM) against LNCaP-FGC (PSMA+) was 40-fold, 40-fold, 21-fold, 5-fold and 40-fold, respectively, higher than that against the non-PSMA-expressing cells HepG2 (IC50 > 40.00 µM), Hela (IC50 > 40.00 µM), MCF-7 (IC50 = 21.68 ± 4.96 µM), DU145 (IC50 = 5.40 ± 1.22 µM), PC-3 (IC50 = 42.96 ± 3.69 µM) cells. Moreover, CPT-HT-J-ZL12 exhibited low cytotoxicity (IC50 > 40 μM) towards MDCK and LO2 cells. The cellular uptake experiment demonstrated the superior PSMA-targeting ability of the CPT-HT-J-ZL12, which was significantly accumulated in LNCaP-FGC (PSMA+), while it was minimized in HepG2 (PSMA−) cells. Further cell apoptosis analyses indicated that it showed a dramatically higher apoptosis-inducing activity in LNCaP-FGC (PSMA+) cells than in HepG2 (PSMA−) cells. Cell cycle analysis indicated that CPT-HT-J-ZL12 could induce cell cycle arrest at the S phase. [ABSTRACT FROM AUTHOR]

Step-by-step solvent extraction was used to regenerate spent clay by recovering the adsorbed oil in lubricating oil refining clay. Several polar and nonpolar solvents were tested, and petroleum ether (90–120°C) and ethanol (95 v%) were selected as the nonpolar and polar solvents, respectively. The spent clay was first extracted using petroleum ether (90–120°C) to obtain ideal oil and then extracted with a mixed solvent of petroleum ether (90–120°C) and ethanol (95 v%) two or three times to obtain nonideal oil before being extracted with ethanol and water. Finally, the clay was dried at 130°C to obtain regenerated clay. The total oil recovery can be more than 99 wt% of the adsorbed oil. The recovered ideal oil can be used as lubricating base oil. Shorter storage times for spent clay produce better regeneration results. The regenerated clay can be reused to refine the lubricating base oils. [ABSTRACT FROM AUTHOR]