10 0 - EleA@UniSA - Università degli Studi di Salerno
10 0 - EleA@UniSA - Università degli Studi di Salerno
10 0 - EleA@UniSA - Università degli Studi di Salerno
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1.5.1 EARLY INVESTIGATIONS ON THE MECHANISM OF ACTION OF BIOACTIVE DIALDEHYDES<br />
Many unsaturated <strong>di</strong>aldehydes, terpenoi<strong>di</strong>c and none, are known to be pungent<br />
on human tongue and it has been shown that all antifeedant <strong>di</strong>aldehydes taste<br />
hot and spicy to the human tongue. Whereas nonantifeedant derivatives are<br />
devoid of hot taste. 25<br />
It has been supposed that both the enal moiety and the other aldehyde group<br />
should be essential for pungency, as well as many other bioactivities.<br />
In earlier investigations Kubo supposed that cysteine was involved, in a Michael<br />
reaction-type ad<strong>di</strong>tion, with unsaturated <strong>di</strong>aldehydes, even if no adduct has ever<br />
been isolated. 26<br />
This expectation was reasonable, since it is known that cysteine reacts<br />
preferably in 1,4 ad<strong>di</strong>tions with -unsaturated <strong>di</strong>aldehydes. Saturated<br />
aldehydes, however, rea<strong>di</strong>ly give thiazoli<strong>di</strong>ne adducts with cysteine.<br />
Taniguchi et al 27 reported that several physiological effects due to polygo<strong>di</strong>al,<br />
e.g inhibition of growth, alcohol fermentation etc appeared to result from its<br />
irreversible reaction with sulfhydryl groups.<br />
However, based on kinetic data, Sodano and co-workers 28 proposed that the<br />
biological activity of the unsaturated <strong>di</strong>aldehyde is primarly related to their ability<br />
to form adducts with amino groups rather than sulfhydryl group on the receptor.<br />
They proposed that the biological mechanisms, investigated under biomimetic<br />
con<strong>di</strong>tions by reaction of terpenoi<strong>di</strong>c <strong>di</strong>aldehydes with methylamine, occurs with<br />
formation of azomethinic interme<strong>di</strong>ate that give a pyrrol-type compound. 29<br />
(Scheme 1.2)<br />
25<br />
Caprioli, V.; Cimino, G.; Colle, R.; Gavagnin, M.; Sodano, G.; Spinella,A. J.Nat.Prod 1987, 50, 146.<br />
26<br />
Kubo, I. , Ganjian, I. Experientia 1981, 37, <strong>10</strong>63.<br />
27<br />
Taniguchi, M.; Adachi, T.; Haraguchi, H.; Oi, S.; Kubo, I.J.Biochem, 1983, 94, 149.<br />
28<br />
D’Ischia, M.; Prota, G.; Sodano, G. Tetrahedron Lett. 1982, 23, 4139.<br />
29<br />
a) Cimino, G.Sodano, G.; Spinella, A.Tetrahedron 1987, 43, 5401. b) Cimino, G.; Spinella, A.; G.Sodano.<br />
Tetrahedron Lett. 1984, 25, 4151.<br />
30
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