Hypotensive Compounds Isolated from the Dried Body of Naja naja Kaouthia LESSON. I. : Isolation of Inosine as a HYpotensive Principle and Structure-Activity Study of Related Compounds

From the dried body of Naja naja Kaouthia from which the internal organs had been removed, three hypotensive compounds were isolated and one of them was identified as inosine.Inosine produced a transient increase in blood pressure followed by a prolonged fall lasting for 30 min in spontaneously hypertensive rats. Next, the relationship between the chemical structure and the hypotensive effect was examined by studying ribose-modified derivatives of inosine. 2'-Deoxyinosine and 3'-deoxyinosine completely lacked hypotensive effect. Phosphorylation at the 3' or 5'-position except for inosine 5'-diphosphoribose and 5'-chloro-5'-deoxyinosine slightly decreased the hypotensive effect. The results indicate that the ribose configuration is important in relation to the hypotensive effect of inosine.