Aim To study a new anti-cancer drug 5-FU-acetic podophyllic ester derivatized from podophyllotoxin. Methods A novel derivative of podophyllotoxin was synthesized. Its inhibitory effects against P-388, A-549, Bel-7402 ...Aim To study a new anti-cancer drug 5-FU-acetic podophyllic ester derivatized from podophyllotoxin. Methods A novel derivative of podophyllotoxin was synthesized. Its inhibitory effects against P-388, A-549, Bel-7402 and HL-60 in vitro were tested. The stability tests under different kinds of conditions were carried out. Results The novel derivative showed stronger inhibitory activities against P-388, A-549 and Bel-7402 in vitro than VP-16. The novel derivative was found to be stable at 60 ℃ and 4500 1x light in solid-state, but was less stable in humid condition. It was more stable in methanol （4 ℃ ） and chloroform （25 ℃ ） than in methanol （25 ℃）, and less stable in artificial gastric juice （ AGJ, 37 ℃ ）. Its stabilities were decreased while increasing the pH of buffer solutions. Conclusion These results could provide useful information for further study of this compound.展开更多
Hybrid antioxidants cinnamoyldopamine（2a）, p-coumaroyldopamine（2b）, caffeoyldopamine（2c）, feruloyldopamine（2d） and sinapoyldopamine（2e） were synthesized by conjugation of dopamine（DA） and hydroxycinnamic a...Hybrid antioxidants cinnamoyldopamine（2a）, p-coumaroyldopamine（2b）, caffeoyldopamine（2c）, feruloyldopamine（2d） and sinapoyldopamine（2e） were synthesized by conjugation of dopamine（DA） and hydroxycinnamic acids（HCAs）. The stabilities were studied in buffers at p H 1.3, p H 5.0, and p H 7.4 including the human plasma. All the compounds were found highly stable at acidic p H, but underwent hydrolysis at neutral p H. Furthermore, the hydrolysis proceeded much faster in plasma in the following order as indicated by half-life values（t1/2）, 2c（1.21 h）〈2e（1.52 h）〈2d（1.85 h）〈2b（3.38 h）〈2a（3.88 h）, correlating with the number of electron-donating groups. It has been proven by UV spectrum that 2c, 2d, and 2e displayed red shift of more than 50 nm as compared to 2a and 2b, because of the presence of OH and OCH3 groups. In addition, the compounds（2b–e） showed no cytotoxicity on normal HUVEC cells as DA, although 2a displayed a 16% inhibition of proliferation at 40 μM following 48 h incubation. Their free radical-scavenging activities were evaluated using ABTS^＊＋ and superoxide anion assays and the mechanisms were proposed. It was found that they all exhibited higher activities than trolox, a recognized antioxidant. Amazingly, in the case of the hybrids（2a–e）, their activity was higher than that of HCAs while lower or comparable to that of DA, suggesting that there may be a ＂saturation effect＂ with the hybrid molecules in the antioxidant activities.展开更多
This study investigated the effect of heat treatment combined with acid and alkali on the angiotensin-I- converting enzyme （ACE） inhibitory activity of peptides derived from bovine casein. The free amino group conte...This study investigated the effect of heat treatment combined with acid and alkali on the angiotensin-I- converting enzyme （ACE） inhibitory activity of peptides derived from bovine casein. The free amino group content, color, and cytotoxicity of the peptides were measured under different conditions. When heated at 100 ℃ in the pH range from 9.0 to 12.0, ACE inhibitory activity was reduced and the appearance of the peptides was significantly darkened. After thermal treatment in the presence of acid and alkali, the free amino group content of ACE inhibitory peptides decreased markedly. High temperature and prolonged heating also resulted in the loss of ACE inhibitory activity, the loss of free amino groups, and the darker coloration of bovine casein-derived peptides. However, ACE inhibitory peptides, within a concentration range of from 0.01 to 0.2 mg/ml, showed no cytotoxicity to Caco-2 and ECV-304 cell lines after heat treatment. This indicated that high temperature and alkaline heat treatment impaired the stability of bovine casein-derived ACE inhibitory peptides.展开更多
In this paper, a nonlinear mathematical model is presented for the transmission dynamics of HIV/AIDS in Cuba. Due to Cuba＇s highly successful national prevention program, we assume that the only mode of transmission ...In this paper, a nonlinear mathematical model is presented for the transmission dynamics of HIV/AIDS in Cuba. Due to Cuba＇s highly successful national prevention program, we assume that the only mode of transmission is through contact with those yet to be diagnosed with HIV. We find the equilibria of the governing nonlinear system, perform a linear stability analysis, and then provide results on global stability.展开更多
基金National Natural Seience Foundation of Gansu Province (3ZS051-A25-101)Fund of the Ministry of Educa-tion of China(No. 204142).
文摘Aim To study a new anti-cancer drug 5-FU-acetic podophyllic ester derivatized from podophyllotoxin. Methods A novel derivative of podophyllotoxin was synthesized. Its inhibitory effects against P-388, A-549, Bel-7402 and HL-60 in vitro were tested. The stability tests under different kinds of conditions were carried out. Results The novel derivative showed stronger inhibitory activities against P-388, A-549 and Bel-7402 in vitro than VP-16. The novel derivative was found to be stable at 60 ℃ and 4500 1x light in solid-state, but was less stable in humid condition. It was more stable in methanol （4 ℃ ） and chloroform （25 ℃ ） than in methanol （25 ℃）, and less stable in artificial gastric juice （ AGJ, 37 ℃ ）. Its stabilities were decreased while increasing the pH of buffer solutions. Conclusion These results could provide useful information for further study of this compound.
基金The National Natural Science Foundation of China(Grant No.21302079)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2014-151)
文摘Hybrid antioxidants cinnamoyldopamine（2a）, p-coumaroyldopamine（2b）, caffeoyldopamine（2c）, feruloyldopamine（2d） and sinapoyldopamine（2e） were synthesized by conjugation of dopamine（DA） and hydroxycinnamic acids（HCAs）. The stabilities were studied in buffers at p H 1.3, p H 5.0, and p H 7.4 including the human plasma. All the compounds were found highly stable at acidic p H, but underwent hydrolysis at neutral p H. Furthermore, the hydrolysis proceeded much faster in plasma in the following order as indicated by half-life values（t1/2）, 2c（1.21 h）〈2e（1.52 h）〈2d（1.85 h）〈2b（3.38 h）〈2a（3.88 h）, correlating with the number of electron-donating groups. It has been proven by UV spectrum that 2c, 2d, and 2e displayed red shift of more than 50 nm as compared to 2a and 2b, because of the presence of OH and OCH3 groups. In addition, the compounds（2b–e） showed no cytotoxicity on normal HUVEC cells as DA, although 2a displayed a 16% inhibition of proliferation at 40 μM following 48 h incubation. Their free radical-scavenging activities were evaluated using ABTS^＊＋ and superoxide anion assays and the mechanisms were proposed. It was found that they all exhibited higher activities than trolox, a recognized antioxidant. Amazingly, in the case of the hybrids（2a–e）, their activity was higher than that of HCAs while lower or comparable to that of DA, suggesting that there may be a ＂saturation effect＂ with the hybrid molecules in the antioxidant activities.
基金supported by the Innovative Research Team of Higher Education of Heilongjiang Province(No.2010td11)the National Natural Science Foundation of China(No.31000801)+1 种基金the National Key Technology R&D Program of China during the 12th Five-Year Plan Period(No.2013BAD18B06)the 2009 Doctoral Science Research of Northeast Agricultural University,China
文摘This study investigated the effect of heat treatment combined with acid and alkali on the angiotensin-I- converting enzyme （ACE） inhibitory activity of peptides derived from bovine casein. The free amino group content, color, and cytotoxicity of the peptides were measured under different conditions. When heated at 100 ℃ in the pH range from 9.0 to 12.0, ACE inhibitory activity was reduced and the appearance of the peptides was significantly darkened. After thermal treatment in the presence of acid and alkali, the free amino group content of ACE inhibitory peptides decreased markedly. High temperature and prolonged heating also resulted in the loss of ACE inhibitory activity, the loss of free amino groups, and the darker coloration of bovine casein-derived peptides. However, ACE inhibitory peptides, within a concentration range of from 0.01 to 0.2 mg/ml, showed no cytotoxicity to Caco-2 and ECV-304 cell lines after heat treatment. This indicated that high temperature and alkaline heat treatment impaired the stability of bovine casein-derived ACE inhibitory peptides.
基金Acknowledgments The authors would like to thank organizers Rongsong Liu, Michael Dillon, and Duane Porter of the Rocky Mountain Mathematics Consortium held at the University of Wyoming in June 2012, which was supported by the National Science Foundation and the Institute for Mathematics and Its Applications.
文摘In this paper, a nonlinear mathematical model is presented for the transmission dynamics of HIV/AIDS in Cuba. Due to Cuba＇s highly successful national prevention program, we assume that the only mode of transmission is through contact with those yet to be diagnosed with HIV. We find the equilibria of the governing nonlinear system, perform a linear stability analysis, and then provide results on global stability.
