Preparation Of Arsanilic Acid-tmp And Its Antibacterial Properties In Vitro And Effects On The Growth Performance Of Piglets

In recent years, the residues of veterinary drugs in animal-derived food draw more and more attention of public. The key to reduce the residues of veterinary drugs in animal-derived food, drug resistance and environmental pressure is to improve the bioavailability and lower the huge demand for veterinary drugs (additives) in large-scale livestock farming. This research is based on acid-base reaction of salt. We utilized arsanilic acid and TMP as the raw materials. Arsanilic acid is widely used as feed additive and TMP is widely used as an antibacterial synergist. We proposed that arsanilic acid could take the place of lactic acid in lactic acid-TMP, and arsanilic acid-TMP can be prepared, which may have better bioavailability. The main results are as follows: 1. The conditions of reaction are as follows:2.000g arsanilic acid and50mL ultrapure water were added to250mL three-necked flask, after completely dissolved on heating, add2.675g TMP. The solution was heated at80℃for3hours under reflux, and cooled to room temperature. Finally, the arsanilic acid-TMP was recrystallized from anhydrous ethanol and precipitated white crystals. The new compound was characterized by IR,1HNMR and melting point. Orthogonal test showed that the best reaction conditions was heated at80℃for3hours under reflux, and the molar ratio of arsanilic acid and TMP was1.1:1.2. In vitro antibacterial activities in which Escherichia coli, Staphylococus aureus, Salmonella pullorum, Shigella flexneri and Micrococcus luteus were used as the tested strains. The results showed that the inhibitory rate of arsanilic acid-TMP increased with the concentration from25μg/mL to100μg/mL against all the five tested strains. The inhibitory rate of100μg/mL arsanilic acid-TMP increased gradually with time. After20min, the drug could achieve pretty good antibacterial effect. The inhibition zone diameter in vitro was determined by Oxford cup. The results indicated that the synthesized salt had greater inhibiting effect on the tested strains than their physical mixture(P<0.05), and all the five kinds of tested bacterias showed high sensitivity to arsanilic acid-TMP ("+++", inhibition zone diameter is longer than20mm). The minimum inhibitory and bactericidal concentration of arsanilic acid-TMP were determined via96microwell plates. The minimum inhibitory concentration (MIC) of arsanilic acid-TMP against Escherichia coli, Staphylococus aureus, Salmonella pullorum, Shigella flexneri and Micrococcus luteus were32、64、256、32、128μg/mL, respectively. The minimum bactericidal concentration (MBC) of arsanilic acid-TMP against Escherichia coli, Staphylococus aureus, Salmonella pullorum, Shigella flexneri and Micrococcus luteus were64、128、256、64、256μg/mL, respectively.3. Weaned piglets were employed as tested animals in the feeding trials and divided into six groups. The six groups were fed with90ppm arsanilic acid,90ppm arsanilic acid+15ppm TMP,45ppm arsanilic acid+7.5ppm TMP,90ppm arsanilic acid-TMP,45ppm arsanilic acid-TMP and250ppm premix products, respectively. After50-day feeding, the results showed that the daily gain of piglets fed with arsanilic acid-TMP was significantly better than that of arsanilic acid and the mixture of arsanilic acid and TMP (p<0.05). Likewise, the feed conversion ratio of arsanilic acid-TMP is significantly lower (p<0.05) which means arsanilic acid-TMP has better bioavailability than arsanilic acid and the mixture of arsanilic acid and TMP. If arsanilic acid-TMP takes the place of arsanilic acid or the mixture of arsanilic acid and TMP, arsenic emissions will be greatly reduced.