Synthesis and biological activity of the mono- and di-galactosyl-vespulakinin 1 analogues

Syntheses are described of some mono‐ and di‐glycosylated analogues of vespulakinin 1. The solid phase procedure, based on the Fmoc chemistry, was used to prepare (Gal α)Thr3‐vespulakinin 1, (Galβ)Thr3‐vespulakinin 1 and the di‐glycosylated analogue ((Gal α)Thr3. (Gal α)Thr4‐vespulakinin 1. The β‐glycosylated derivative was also prepared by the continuous flow variant of the Fmoc polyamide method. The synthesized glycopeptides were purified and characterized by amino acid analysis, optical rotation, analytical HPLC, 1H‐and 13C‐NMR and FAB‐MS. Preliminary pharmacological experiments showed that the carbohydrate‐free vespulakinin 1 is less active than bradykinin (about 0.3 times on a molar basis) when tested by guinea pig rectum contraction, and the two monoglycosylated analogues are equiactive (about 0.9 times the bradykinin activity). The most active derivative, the (Gal α)Thr3, (Gal α)Thr4‐vespulakinin 1 analogue, was about 2.5 times as active as bradykinin.