الفهرس 
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Abstract
Flavones are well distributed and have multifunctional activities in plant kingdom; one of these functions is protecting plants from microbial infection. Therefore, flavones were chosen to be prepared with various substitutes to maximize their activity and shed some lights on the structure feature required to enhance their fungicidal activities. A series of substituted 2 - phenyl - 4H -benzopyran- 4 - one (flavones) namely flavone (A), 3’-methylflavone (B), 4’-methoxyflavone (C) and 4’-bromoflavone (D) were synthesized according to Baker–Venkatarman outline and characterized by their physical properties and the spectroscopic techniques (UV-Vis, IR, 1HNMR and Mass spectroscopy).
The purity of the compounds were judged by the adequacy of their spectra. The UV-spectrum of the prepared flavone (A) showed bands I and II at 294 and 255 nm respectively similar to the reported values. IR spectrum of flavone (A) shows the expected characteristic peaks. The carbonyl group shows a C=O str. absorption at considerably low frequency (1645 cm-1) because of the conjugation with ring A on one side and the double bond and ring B on the other side. The aromaticity is presented by the peaks 767, 1569 and 1606 cm-1. The C-H str. of SP2 carbons is shown at 3060 cm-1. 1HNMR spectrum of flavone (A) was recorded in deuterated chloroform that showed a peak at 7.27 ppm. The olefinic proton (3H) is shown downfield at 7.00 ppm because of conjugation with the carbonyl group and the phenyl B ring. The aromatic protons of rings A and B appear in the range 7.47-8.26 ppm. Proton 5H shows the most downfield peak at 8.24 ppm because of the neighboring carbonyl group; the peak appears as doublet with coupling constant 8Hz. Each of the aromatic protons 6H, 7H, and 8H appears as multiplet at 7.64, 7.76, and 7.47. Protons of ring B, the two 2’H and the three 3’ and 4’ protons appear as multiplets at 7.96 and 7.57 respectively. The integration confirms these assignments.
The synthesized flavones along with some natural flavonoids; quercetin (E), chrysin (F) and naringinin (G) were examined for their antifungal activity. The result indicated that compounds A, B and C were more active compounds against both fungi than the other compounds including the natural flavonoids. This result suggests increasing the fungicidal activity of flavones with increasing the hydrophobicity represented by the hydrophobicity parameter (π) as expressed by the following equation for fungitoxicity against Alternaria alternatae:
EC50 (mmol) = 1.71 ( ± 0.11) + 0.69 (0.22) π
r = 0.915 , P ≤ 0.1 SE= 0.163, n=4
Although the correlation of Fusarium oxisporum was lower (r = 0.562), the conclusion is also applicable on the natural flavones (E and F) with five and two hydroxyl groups respectively since their activities against both organisms increased with increasing their hydrophobicity i. e. F > E. The correlation suggests that the permeability of the cellular membranes , with the lipophilic nature; is affected by the examined compounds.