Original scientific paper

Inhibition of Hill Reaction by 3-Alcoxyuracil Derivatives: QSAR Study With Topological Indices

Milan Šoškić ; Department of Chemistry, Faculty of Agricultural Sciences, University of Zagreb, 41000 Zagreb, Croatia, Yugoslavia
Aleksandar Sabljić ; Institute Rudjer Bošković, P.O.B. 1016, 41001 Zagreb, Croatia, Yugoslavia

Abstract

This study was undertaken to find cl simple and accurate structural parameter for the quantitative description of inhibitory potency of alcoxyuracils in the Hill reaction and to gain more information about the mechanism of inhibition on the molecular level. A very good correlation (1' = 0.987) was obtained between pho values (negative logarithm of the concentration that causes 50% inhibition) and the valence first-order and the fifth-order molecular connectivity indices. This model, when compared with the empirical models based on the n-octanol/water partition coefficients, shows superior or at least comparable performances in accuracy and range of applicability. In addition, the direct correspondence between molecular structure and the above connectivity indices make s it possible to locate structural features responsible for the inhibitory potency of alcoxyuracils in the Hill reaction and to learn more about the mechanism of inhibition on
the molecular level. From our QSAR analysis, the interaction
between the chloroplast receptor site and alcoxyuracils, which
cause inhibition of Hill reaction, can he viewed as a two-stage
mechanism. The first stage is a complex formation beteween the
uracil ring and some active site of chloroplast. The second stage
is a hydrophobic interaction between the alcoxy chain and cl hydrophobic region close to the active site. It is assumed that this stage proceeds by the »zipper- mechanism and that it accounts
or the quantitative differences in inhibition found for the studied
alcoxyuracils.

Keywords

Hrčak ID:

176404

URI

https://hrcak.srce.hr/176404

Publication date:

23.12.1987.

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