| Gentamicin (GM) is a group of multi-component aminoglycoside antibiotics with similar structure,mainly composed of C complex ethnic-based. Gentamicin has been used to treat infections with a variety of Gram-positive and Gram-negative bacteria. C1, one component in the key compound group C, has little toxic side effect and drug resistance, but not as effective as C2 and C1a. In contrast, C2 and C1a have higher efficacy, but also higher toxicity and drug resistance. At present the balancing of different components is mainly through controlling the fermentation procedure. Recently it is found that GM C1a can be used as a precursor chemical of antibiotics Etimicin and it has a promising application in many other fields too. However, the existing procedure and techniques are way backward, therefore it's important to find a way to isolate GM C1a components from the GM complex.The detection of gentamicin components: on the basis of TLC, iodine vapor was compared with fluorescence as reveal reagent. Impact factors of these two systems were also tested (such as the activation time, activation temperature, the compose proportion of developing reagent.) We found that fluorescence can separate more components and therefore is more suitable for qualitative detection. For quantitative studies, colorimetry and brightness can be used. Though brightness method brought in more errors, it provides us another angle to solve the problem. TLC(with iodine steam as reveal reagent) was combined with colorimetry to establish a rapid and accurate method for determination of gentamicin components. Parameters for this GM standard curve: regression equation: Y = 0.00892X-0.02393, r = 0.9986; linear range: 2mg～100mg; RSD of three components: 0.19%,0.27% and 3.70%. Test results were basically consistent with the standards content of Pharmacopoeia with a high accuracy. This method has been applied in follow-up experiments. Detection of gentamicin sample yielded the result as C1a, C2, C1: 32.9%, 39.4% and 27.7%Ion exchange properties of Gentamicin: static method was used to study the adsorption dynamics curve of gentamicin and its components. After 160 mins, the adsorption of gentamicin reached the balance with exchange capacity up to 8 mmol / g. The exchange capacity of gentamicin C1a, C2, C1 component were 2.55,3.15 and 2.31 mmol / g. Adsorption dynamics curve of Gentamicin showed that the adsorption of the three components was simultaneously increased as the concentration ratio. The impact of adsorption temperature was ignored as it was not significant. When the pH=8 gentamicin and its components reached the maximum exchange. When the pH = 9 ~ 10, the absorption capacity of gentamicin C1a was significantly different from the other two components. Taking advantage of this difference, we did desorption experiment and established the 1.5 M and 2.0 M as the gradient elution concentration to elute gentamicin.The impact of resin synthetic conditions on gentamicin components separation: the extreme cases of the physical structure of the resin, the ratio of single, cross-linked and Hydrolytic-factor were studied. We found that the hole had little effect for ion exchange of Gentamicin, thus was neglected. Key factors were optimum cross-linking and MMA optimum amount. The importance of Hydrolysis conditions is: hydrolysis time> concentration of NaOH > hydrolysis temperature. Based on results from these single factors, we determined factors and levels to use in orthogonal experiments. Applying full exchange capacity, the relative exchange capacity of gentamicin, the content of GM in the last desorption and the concentration of C1a as target, we found the best Combination was 3% MMA, 6% cross-linking and 6h hydrolysis time. In final verification, wholly-exchange resin reached 8.23 mmol / g capacity, 96.7% as the relative exchange capacity of gentamicin. The concentration of C1a in the second eluate is up to 96.28%. According to the orthogonal experiment these results are certifiable.
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