Accumulation And Metabolism Of Three Typical Sulfonamide Antibiotics In Chinese Cabbage

The abuse of sulfonamide antibiotics leads to a large number of sulfonamide antibiotics and their acetylated metabolites entering farmland.Whether the crops will absorb sulfonamides and acetylated metabolites and causing a potential threat through the food chain to human health is a hot topic of concem.Therefore,the study on the accumulation and metabolism of sulfonamide antibiotics in Chinese cabbage can provide basic data for a comprehensive understanding of the environmental outcome and ecological toxicological effects of sulfonamide antibiotics,which has theoretical and practical significance.Firstly,the analytical methods of sulfadiazine,sulfmethazine,sulfamethoxazole and their acetylated metabolites were established.On this basis,the accumulation and distribution of three sulfonamide antibiotics in Chinese cabbage were studied by hydroponic experiment.The differences of the accumulation ability of three sulfonamide antibiotics and their acetylated metabolites in Chine-se cabbage were compared.The effects of pH value of culture solution on the acc-umulation of sulfonamide antibiotics in Chinese cabbage were investigated.The metabolic sites and possible metabolic mechanisms of sulfonamide antibiotics in Chinese cabbage were studied.The results are as follows:1.The simultaneous detection of six compounds can be realized in a short time using 0.1%phosphoric acid solution as extraction solvent and ultrasonic extraction to extract the target compound,The addition concentration of Chinese cabbage was 0.01 mg/kg-1 mg/kg,the recovery was 66.33%-107.33%,RSD was less than 16%.The limits of detection of six compounds were between 0.79ng/L-2.03ng/L,The limits of quantitation of six compounds were between 2.64 ng/L-6.75ng/L.The method has high sensitivity,good reproducibility,low detection limit,good accuracy and wide adaptability.It can quantitatively determine sulfonamide antibiotics and their acetylated metabolites in vegetables.2.Hydroponic accumulation experiments showed that the distribution of three sulfonamide antibiotics in different parts of Chinese cabbage was different The accumulation content in roots was the highest,while that in stems was the lowest.The accumulation capacity of three sulfonamide antibiotics was also different.In the hydroponic solution under the same concentration,SM2 accumulation in root stem and leaf was highest,followed by SDZ and SMZ accumulation were the lowest.LogDow was calculated according to the LogKow value of three sulfonamide antibiotics and the pH of culture solution.3.The differences in the accumulative capacity of sulfonamide antibiotics and acetyled sulfonamide metabolites were compared.The results showed that sulfadiazine acetylated metabolites accumulated in different parts of Chinese cabbage.The accumulation of sulfadiazine acetylate metabolites in roots,stems and leaves of Chinese cabbage is higher than that of the parent,and its accumulation ability is stronger.4.The accumulation of sulfainethoxazole in vegetables was affected by pH.Within the range of pH 4-6.5,the accumulation of sulfamethoxazole in roots,stems and leaves of Chinese cabbage decreased gradually with the increase of pH in culture soution.According to the calculated ionic morphology ratio of sulfamethoxazole at different pH,the proportion of sulfamethoxazole neutral molecule in hydroponic solution gradually decreased with the increase of pH,which was the main reason for the accumulation of sulfamethoxazole in Chinese cabbage.It can be seen that the neutral molecular states of sulfonamides are mainly absorbed by Chinese cabbage.5.Comparing the metabolites of three sulfonamide antibiotics in different parts of Chinese cabbage,it was found that the three sulfonamide antibiotics had the highest metabolites content in roots and the lowest metabolites content in stem.It can be seen that sulfonamide antibiotics are mainly metabolized in the roots after they are absorbed by vegetables.The metabolite content of SM2 is the highest and the metabolite content of SMZ is the lowest,and it follows the same rule in root,stem and leaf.6.The analysis of RNA-seq reverse transcription suggested that the enzymes involved in sulfamethazine metabolism in roots of Chinese cabbage might be related to P450 enzymes.It may be related to glucose 3-o-glucan transferase,hydrogen peroxidase,redox enzyme,peroxidase and xylose transferase,peroxidase,aspartate esterase,xylose transglycosidase,etc.