| Diosgenin was an important steroidal saponins ingredient, widely existed in Dioscoreaceae, Liliaceae, Caryophyllaceae, Rosaceae and other medicinal plants. Diosgenin also had many pharmacological activities such as anti-tumor, anti-inflammatory, hypolipidemic and hypoglycemic and so on. In recent years, anti-tumor effect of diosgenin has caused widely concern in the world. However, preclinical pharmacokinetic studies have found that the oral absorption rate was slow and the bioavailability was low of diosgenin.Currently, the methods to improve the diosgenin solubility and dissolution were mainly focused on the drug design stage of its structural modification and transformation. Amino acid was an amphiphilic compound, and using amino acid as a vector introduced into the medicament was a new discovery in recent years, this technique not only improved the solubility, promoted absorption strengthened the active transport, but also increased the oral bioavailability of drugs. Although some scholars have prepared parts of L-amino acid derivative of diosgenin, but its bioavailability whether increase was not clear.To confirm this circumstance, the paper based on the previous studies, the anti-tumor activity and pharmacokinetic of new L-valine diosgenin ester were studied, and the main contents and results as follows:1. Determination of RP-HPLC and study of anti-tumor activity of L-valine diosgenin esterIn this experiment, the new compound of L-valine diosgenin ester was composed, and the RP-HPLC analysis method was established to investigate the anti-tumor effect of L-valine diosgenin ester. The results showed that the large amounts of L-valine diosgenin ester were composed by using esterification reaction method, and the RP-HPLC condition was established as follows: the mobile phase was methanol-water(95: 5); column temperature was 35 ℃; flow rate was 1.0 ml/min; injection volume was 20μl and wavelength was 210 nm. In addition, the new composed L-valine diosgenin ester could significantly inhibite the growth of human tumor cells in vitro and in vivo. In vitro, it could inhibite the human adenoid cystic carcinoma ACCM, S-180 proliferation of mice transplanted tumor cell, and in vivo it could inhibite the S-180 proliferation of mice tumor cells.2. Studies on the oral bioavailability of L-valine diosgenin esterIn this paper, the pharmacokinetics of new compound L-valine diosgenin ester was studied in rats vivo. The changes of plasma concentration were investigated by RP-HPLC method after rats accepted 40 mg/kg(i.g. and i.v.) L-valine diosgenin ester and the pharmacokinetic parameters and oral bioavailability degree were calculated and analyzed by DAS 2.0 software.The results showed that in the intragastric administration group Cmax was 9.8 ± 0.5 μg/ml, Tmax was 32.9 ± 5.7 min, T1/2 was 60.1 ± 10.2 min, AUC was(1.5 ± 0.4) × 103 μg/min·ml; in the intravenous group T1/2 was 74.6 ± 16.5 min, AUC was(1.2 ± 0.3) × 104 μg/min·ml. Therefore, the oral bioavailability of L-valine diosgenin ester was 12.5%, with respect to the diosgenin was increased.3. Studies on the absorption characteristics of L-valine diosgenin ester in rats intestinal eversion testIn this paper, the absorption characteristics of new compound L-valine ester diosgenin in rats intestines eversion test were studied. The absorption characteristics in the different parts of guts such as duodenum, jejunum, ileum were analyzed by copying rats models and using RP-HPLC method to calculate the parameter of absorption rate parameter of L-valine diosgenin ester. The results showed that different doses of L-valine diosgenin esters were all represnted linear absorption in each intestines(R > 0.9), which was the zero-order absorption; and the absorption rate constant K value of L-valine diosgenin ester were increased linearly with the concentration(P <0.05), indicating that the absorption was passive absorption; the different parts of intestine experiments showed that the drug absorption of the duodenum was significantly greater than the jejunum and ileum, but the drug absorption between the jejunum and ileum had little difference; however, under the different drug concentration, the trend of the different parts of the intestinal absorption was duodenum> jejunum> ileum. Therefore, L-valine diosgenin ester in different parts of the intestinal absorption were in the line with the zero-order absorption rate, the absorption form may be passive.4. Studies on the distribution of L-valine diosgenin ester after intragastric administrationIn this paper, the distribution of the new compound L-valine diosgenin ester in the rats organs were studied. Using RP-HPLC method to determine the drug content of rats ester, liver, kidney, heart, spleen, lungs, brain after intragastric administration of L-valine diosgenin. The results showed that the linear relationship between the measurement of biological samples and drug content was good(R>0.998); the RSD detection of intra-day and intre-day precision of low concentration was not exceed 10%, and middle and high concentration were not exceed 5%; the recovery rate was not less than 70%; Meantime, the total content of the drug in the liver was 4.53 ± 1.02 μg/g, which was highest in all rats organs, next was the lungs content 1.88 ± 0.37 μg/ g, and the total drug content of brain was lowest, which was 0.43 ± 0.10 μg/g; the drug content of the same organs were different in different time, and 2 h drug content was 6.19 ± 2.09 μg/g, significantly higher than the 1 h and 5 h. However, the 2 h drug content in the liver was 2.21 ± 0.79 μg/g, which was the maximum at all time points. Therefore, the drug content in the liver was highest, in the brain was lowest after intragastric administration of L-valine diosgenin.5. Studies on the excretion of L-valine diosgenin ester after intragastric administration of Lvaline diosgenin ester.In this paper, the excretion characteristics were studied after intragastric administration new compound L-valine diosgenin ester in rats, and the bile was collected after intragastric administration 24 h, and the urine and feces were collected within 48 h, and then using RP-HPLC method investigated the bile, urine and feces content, then calculated the cumulative excretion, excretion rate, and rate of excretion. The results showed that the bile accumulation excretion was 6.35 ± 0.40μg, accumulated excretion rate was 0.16 ± 0.01%, excretion rate was 0.26 ± 0.02 μg/h; and the urine accumulation excretion was 124.12 ± 10.51μg, accumulated excretion was 3.10 ± 0.26%, excretion rate was 2.59 ± 0.21 μg/h; and the fecal accumulated excretion was 3591.74 ± 207.19 μg, accumulated excretion rate was 77.50 ± 3.17%, excretion rate was 124.83 ± 4.32 μg/h. Therefore, the main excreted way of L-valine diosgenin ester after intragastric administration was the fecal, and excreted whih prototype. |
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