ABSTRACT
@#Objective To optimize a shake flask culture medium for Escherichia coli(E.coli)with high biomass and viability using artificial neural networks(ANN). Methods Using the proportion of glucose(Glu),yeast extract(YE),yeast peptone(YP),soy peptone(SP)and yeast nitrogen base(YNB)as the mixture component,and the A_(600)(A1)value of cell suspension,wet bacterial weight(G,g/L)of culture and cell viability(A2,A_(460))as the response values,the mixture design was used to screen the mixture components that had a significant effect on the response value. The ANN model was constructed with the test results of mixture design as training and verification data samples. The input variables were mixture components and restricted the upper and lower limits of the mixture components,and the output variables were mixture design response values. The optimized medium formula and reference values were obtained by the constructed ANN. The medium formula was further adjusted by Monte Carlo simulation to obtain the shake flask medium formula of E.coli,which was then verified for 10 times. Results The shake flask culture medium of E.coli was composed of Glu 26 g/L,SP 26 g/L,YNB13 g/L with the total concentration of 65 g/L. The verification results showed that the probability of A1 ≥ 14 was 60%,the probability of G ≥ 77 g/L was 50% and the probability of A2 ≥ 11 was 40%. The mean values of the incubation result data were equivalent to the reference values. Conclusion The shake flask culture medium of E.coli optimized in this study can obtain E.coli with high biomass and bacterial activity.
ABSTRACT
Among the methods described for determining the solubility, shake-flask is suitable to evaluate the equilibrium solubility according to the BCS. Nevertheless, experimental conditions related to the shake-flask method are not well described. Evaluating the effects of experimental conditions on solubility measurements by shake-flask method is important and contributes in biowaiver decision. For this work, propranolol hydrochloride and nimesulide were used as model compound of high and low solubility, respectively. Equilibrium solubility was evaluated at 37 ºC, 100 rpm during 48 hours in buffer media. Effects of the rotation speed, temperature, substance in excess and aliquot withdrawn were evaluated. Small variations of temperature caused significant differences in the solubility and then this parameter must be controlled. Excess of raw material influenced the results of the nimesulide, then, little excess is recommended. Rotation speed did not cause differences in the equilibrium solubilities, but at 150 rpm the equilibrium was reached faster. Aliquot did not present significant differences, but excessive withdrawn should be avoided. Therefore, the evaluation of equilibrium solubility using shake-flask method must be performed in physiological pH conditions, 37 ± 1 ºC, substance in excess 10% above saturation, 50, 100 or 150 rpm and aliquot withdrawn not more than 10% of the media volume.
Subject(s)
Solubility , Batch Cell Culture Techniques/methods , Pharmaceutical Preparations/administration & dosageABSTRACT
OBJECTIVE: To introduce the basic procedure and technical requirements of equilibrium solubility experiments and provide reference for design and conduct of equilibrium solubility experiments scheme. METHODS: The concept and influence factors of solubility, principle and determination method of solubility experiments, equilibrium solubility project of world health organization were analyzed. RESULTS: The influence factors of equilibrium solubility include composition of buffers, temperature, time of oscillation, time of sedimentation, techniques for separation of solid and liquid phases etc. CONCLUSION: To ascertain the BCS classification of drugs, the first step is to determine the equilibrium solubility of drugs under physiological pH conditions. To date, there is no accepted standard method for the determination of equilibrium solubility. This paper introduces the basic procedure and technical requirements of equilibrium solubility experiments recommended by WHO, which would provide instructive and practical assists to conduct of equilibrium solubility experiments and standardize its application in BCS classification and biowaiver.
ABSTRACT
n-Octanol/ water partition coefficients (Kow ) is an important parameter commonly used to explain toxicity, activity and transmembrane of drugs. However, it is difficult to be detected by direct experimental determination. In this work, a set of 29 neutral and acidic analogues of naphthalene and anthraquinone with reliable experimental Kow data was chosen as model compounds for establishing linear relationship between the logarithm of apparent n-octanol/ water partition coefficient (lgKow), and the logarithm of reversed phase-high performance liquid chromatography (RP-HPLC) retention factor of the solutes corresponding to neat aqueous fraction of mobile phase (lgkw ) as the quantitative structure-retention relationship (QSRR) model. Methanol-water mixture was used as mobile phase at various pH, and retention time (tR ) was rectified by a dual-point retention time correction (DP-RTC) in this method. The experiment results indicated that the proposed QSRR model had good correlation coefficient R2 = 0. 974 -0. 976 with satisfactory results of internal and external validation (the cross-validated correlation coefficient R2cv of 0. 970-0. 973, and 1. 4% ≤relative error (RE)≤7. 9% for all the 6 verification compounds). In addition, this QSRR model was compared with linear solvation energy relationship ( LSER) involved in different descriptors of molecular structure, showing no differences. The QSRR model was applied to measure Kow of 11 naphthalenes and anthraquinones, and the predicted data were compared with Shake-flask method (SFM) experimental ones, as well as calculated ones obtained by software. The results suggested that the proposed method for Kow determination in this work was more accurate, simple and fast. To the best of our knowledge, this is the first report on measuring Kow data for these compounds. The proposed strategy provides the possibility in determining Kow of lipophilic components in complex mixture more quickly and accurately by RP-HPLC.