Antiviral activity of C-5 substituted tubercidin analogues.

The pyrrolo[2,3-d]pyrimidine nucleoside antibiotics tubercidin, toyocamycin, and sangivamycin and the synthetic analogues 5-chloro-, 5,6-dichloro-, 5-bromo-, 6-bromo-, 5,6-dibromo-, 5-iodo-, 5-(1-hydroxyethyl)-, 5-(1-methoxyethyl)-, (E)-5-(2-bromoethenyl)-, (E)-5-(2-cyanoethenyl)-, 5-(2-buten-1-yl)-, 5-(3-hydroxypropyl)-, and 5-butyltubercidin were evaluated for their antiviral properties against six RNA viruses and three DNA viruses in HeLa cell, primary rabbit kidney cell, and Vero cell cultures. Most of the derivatives had substantial activity against the RNA viruses, with the least activity shown by 6-bromo-, 5,6-dichloro-, and 5,6-dibromotubercidin. The C-5 substituted derivatives were quite toxic for the host cells. 5-(1-Hydroxyethyl)-, 5-(1-methoxyethyl)-, and 5-(2-buten-1-yl)tubercidin were more selective against reovirus type 1, parainfluenza virus type 3 and Coxsackie virus B4 than tubercidin and the 5-halotubercidins. When tested for in vivo activity against Coxsackie B4 virus infection in newborn NMRI mice, 5-(1-hydroxyethyl)- and 5-(1-methoxyethyl)tubercidin caused a significant decrease in the mortality rate at a dose level of 100 micrograms per mouse. The inhibitory effects on L-1210 cell growth were also determined, and toyocamycin (ID50 = 0.006 micrograms/mL) was found to be the most active compound. This study demonstrates the significance of structural modification at C-5 and the potential of C-5 substituted analogues of tubercidin as biologically active agents.

Analysis for total sulfite in foods by using rapid distillation followed by redox titration.

A rapid and accurate analysis for total sulfite as sulfur dioxide has been developed for foods and food products. The method, which combines a selective distillation cleanup procedure with the selective redox titration of sulfite ion by iodine, has been applied to a variety of foods and food products over a period of time with no significant interference encountered in any matrixes other than garlic and leeks. For the foods analyzed, the method typically shows a detection limit of 10 ppm, a relative standard deviation of 7.5% (compared with 10.4% for similar matrixes by the Monier-Williams method), and recoveries of 97.9 +/- 6.4%. Comparison of results for this method with those obtained using the Monier-Williams method showed a mean value for the distillation/titration method of 241 ppm compared with 242 ppm for the Monier-Williams method. A correlation of 0.991 and odds of a difference between methods of 10.7% (Student's paired t-test (1-alpha) X 100) were obtained for those matrixes where no interferences were encountered with either method.