No abstract

Diketo acids such as S-1360 (1A) and L-731,988 (2) are potent and selective inhibitors of HIV-1 integrase (IN). A plethora of diketo acid-containing compounds have been claimed in patent literature without disclosing much biological activities and synthetic details (reviewed in Neamati, N. Exp. Opin. Ther. Pat. 2002, 12, 709-724). To establish a coherent structure-activity relationship among the substituted indole nucleus bearing a beta-diketo acid moiety, a series of substituted indole-beta-diketo acids (4a-f and 5a-e) were synthesized. All compounds tested showed anti-IN activity at low micromolar concentrations with varied selectivity against the strand transfer process. Three compounds, the indole-3-beta-diketo acids 5a and 5c, and the parent ester 9c, have shown an antiviral activity in cell-based assays. We further confirmed a keto-enolic structure in the 2,3-position of the diketo acid moiety of a representative compound (4c) using NMR and X-ray crystallographic analysis. Using this structure as a lead for all of our computational studies, we found that the title compounds extensively interact with the essential amino acids on the active site of IN.

An experiment was carried out using dairy ewes to study the transfer of aflatoxin B1 (AFB1) from feed to milk and from milk to cheese. The effects of AFB1 on liver function and hematological parameters were also investigated. Fifteen ewes were assigned to treatments in replicated 3 x 3 Latin squares. The experimental groups received 32, 64, or 128 microg/d of pure AFB1 for 7 d followed by 5 d of clearance. On the sixth day of the first period, the total daily milk produced by each ewe was collected separately and processed into cheese. The results indicate that the level of AFB1 used did not adversely affect animal health and milk production traits. The aflatoxin M1 (AFM1) concentrations in milk approached a steady-state condition in all treated groups between 2 and 7 d after the start of treatment. The mean AFM1 concentrations of treated groups in steady-state condition (184.4, 324.7, and 596.9 ng/kg in ewes fed 32, 64, or 128 microg of AFB1, respectively) were significantly affected by the AFB1 doses. The AFM1 concentration was linearly related to the AFB1 intake/kg of BW. The carry-over values of AFB1 from feed into AFM1 in milk (0.26 to 0.33%) were not influenced by the AFB1 doses. The AFM1 concentrations in curd and whey were linearly related to the AFM1 concentrations in the unprocessed milk.

No abstract

An experiment was carried out to investigate 1) the transfer of aflatoxin M1 (AFM1) into the milk of dairy ewes fed diets naturally contaminated with aflatoxin B1 (AFB1); 2) the effect of the addition of dried yeast culture in the diet on this transfer; and 3) the alteration of enzymatic activities in the liver of ewes fed diets contaminated with AFB1. Twenty-four Sarda dairy ewes were divided in 4 groups and fed a concentrate mix containing 4 amounts of wheat meal naturally contaminated with aflatoxins. The diet of the control group had no wheat meal, whereas that of treated groups had low, medium, or high amounts of contaminated wheat, which corresponded to 1.13, 2.30, and 5.03 microg of AFB1/kg of feed, respectively. The experiment lasted 14 d. On d 8 to 14 from the beginning of the trial, 12 g/d of a commercial dried yeast product (DYP) of Kluyveromyces lactis was added to the diet of each ewe. The AFM1 concentration in individual milk samples and the blood serum metabolites were measured periodically. The presence of AFM1 was first detected in milk on d 1 of administration, and then its concentration increased and approached a steady-state condition on d 3 simultaneously in all treated groups. The AFM1 in milk at the steady-state condition, which was linearly related to the AFB1 intake, was 39.72, 50.38, and 79.29 ng/L in the low-aflatoxin, medium-aflatoxin, and high-aflatoxin groups, respectively. The AFM1 concentration in milk of the high-aflatoxin group was approximately 1.5-fold greater than the European Commission maximum tolerance level (50 ng/kg). The addition of DYP to the diet did not affect the AFM1 concentration in milk. After the withdrawal of the contaminated concentrate mix, the AFM1 mean concentrations decreased quickly and were no longer detected after 3 d in all treated groups. Daily milk yield and composition did not differ because of aflatoxin treatment. Blood serum parameters (creatinine, glutamic oxalacetic transaminase, glutamic pyruvic transaminase, gamma glutamyl transferase, alkaline phosphatase, lactate dehydrogenase, cholesterol, protein, urea, calcium, and phosphorus) were not influenced by AFB1 intake. Therefore, the effect of DYP on certain blood parameters (gamma glutamyl transferase, urea, creatinine, and calcium) could not be attributed to amelioration of the aflatoxin-contaminated diet. In conclusion, diet contamination by AFB1 near the European Union tolerance level (0.005 mg/kg) in complete feed for dairy animals (e.g., high-aflatoxin group) can result in an AFM1 milk concentration higher than the European Commission maximum tolerance level. Transfer of aflatoxin from feed to milk was not affected by dietary addition of a commercial DYP.

No abstract

HIV-1 integrase (IN) is an attractive and validated target for the development of novel therapeutics against AIDS. Significant efforts have been devoted to the identification of IN inhibitors using various methods. In this context, through virtual screening of the NCI database and structure-based drug design strategies, we identified several pharmacophoric fragments and incorporated them on various aromatic or heteroaromatic rings. In addition, we designed and synthesized a series of 5-aryl(heteroaryl)-isoxazole-3-carboxylic acids as biological isosteric analogues of beta-diketo acid containing inhibitors of HIV-1 IN and their derivatives. Further computational docking studies were performed to investigate the mode of interactions of the most active ligands with the IN active site. Results suggested that some of the tested compounds could be considered as lead compounds and suitable for further optimization.

No abstract