Synthesis of angelicin heteroanalogues: preliminary photobiological and pharmacological studies.

A series of angelicin heteroanalogues, in which the furan was replaced by thiophene or a 1-substituted pyrazole moiety, was synthesised in order to obtain potential therapeutic agents with antiproliferative and/or other biological activities. In general, the antiproliferative activity of the new thioangelicin, tested in different biological substrates, appeared to be higher than that of the angelicin, the natural parent compound, but lower than that of 8-MOP, the furocoumarin ordinarily used in PUVA therapy and photopheresis. Thioangelicin 6 induced strong inhibition of T2 bacteriophage infectivity and was able to significantly repress the DNA synthesis in Ehrlich ascites cells and the clonal growth in HeLa cells. The pyrazolocoumarins did not show any noticeable effect upon UVA irradiation in all the biological systems considered. All the new angelicin heteroanalogues appeared to be free of the known phototoxicity of furocoumarins on the skin. The pyrazolocoumarins have also been tested as anti-inflammatory, analgesic, antipyretic, local anaesthetic, anti-arrhythmic and platelet anti-aggregating agents by standard procedures. In this class of derivatives, 10a showed good anti-inflammatory and antipyretic properties, while 9a and 11a showed significant local anaesthetic activity.