STRUCTURE-ACTIVITY STUDIES OF PHOTOACTIVATED ANTIVIRAL AND CYTOTOXIC TRICYCLIC THIOPHENES

The photoactivated antiviral and cytotoxic activities of the naturally occurring thiophene, alpha-terthienyl (1), and 15 synthetic analogues were evaluated against murine cytomegalovirus and Sindbis virus, and murine mastocytoma cells. After irradiation with near UV light, alpha-terthienyl and most of its analogues had significant toxicity, with minimum inhibitory concentrations in the range of 0.02-40 microM. In the absence of near UV irradiation, only one analogue had antiviral activity and five were cytotoxic. The most active analogues were those containing carboxylic acid, hydroxyl, or cyano substituents. Quantitative structure-activity relationship analysis of thiophene phototoxicity suggested that the rate of singlet oxygen production is the primary determinant of antiviral and cytotoxic activities. For phototoxicity against murine cytomegalovirus, a significant role for hydrophobicity was also demonstrated. Tricyclic thiophenes show significant potential for photochemotherapy of viral infections and cancer, and further evaluation in animal models is recommended.     

Synthesis and characterization of alkyl-, alkenyl-, acyl- and nitrogen-substituted derivatives of the potent phototoxin α-terthiophene

Some alkyl-, alkenyl-, acyl- and nitrogen- derivatives of α-terthienyl 1 have been synthesized in an effort to expand the potential insecticidal activity profile of this compound. The introduction of substituents was carried out directly on the α-terthienyl molecule. Three compounds were isolated in the nitration reaction and the compounds have been identified as 5-nitro-2,2′:5′,2″-terthiophene 5 , 3′-nitro-2,2′:5′,2″-terthiophene 6 and 3-nitro-2,2′:5′,2″-terthiophene 7 respectively. Preliminary results of biological acitivity are reported.