Twenty-one substituted 1,4-naphthoquinones and five 8-quinolinols and copper(II) chelates were tested for antifungal activity against Candida albicans and Trichophyton mentagrophytes. Compounds containing electron-releasing or weak electron-withdrawing groups in the 2 and 3 positions of the 1,4-naphthoquinone ring were the most active against C. albicans at pH 7.0 in the presence of beef serum in the following order: 2-CH3O = 2,3-(CH3O)2 greater than 2-CH3 greater than 2-CH3S greater than 2-NH2 greater than 2,6-(CH3)2. For T. mentagrophytes under the same conditions the inhibitory 1,4-naphthoquinones contained the substituents 2-CH3O greater than 2,3-(CH3O)2 greater than 2-CH2S greater than 2-CH3 greater than 2-CH3(NaHSO3) greater than 2-NH2 greater than 2-C2H5S, 3-CH3 greater than 2,6-(CH3)2 greater than 2,3-CL2 greater than 5,8-(OH)2.
Thirteen 2-alkynoic acids and their methyl esters (C3--C12, C14, C16, and C18) were tested against Aspergillus niger, Trichoderma viride, and Myrothecium verrucaria in Sabouraud dextrose agar at pH 4.0 and 5.6. Toxicity to Candida albicans, Trichophyton mentagrophytes, and Mucro mucedo was determined in the same medium at pH 5.6 and 7.0 in the absence and presence of 10% beef serum. The fungitoxicity of the acids was influenced by chain length, pH of the medium, and absence or presence of adsorbents. The toxicity of the esters was influenced primarily by chain length and to a lesser extent by the pH of the medium and the presence of beef serum. The order of activity of the 2-alkynoic acids is C10=C11=C12 greater than C14=C16 greater than C9 greater than C8 greater than C7. When compared with other fatty acid analogs, the order of fungitoxicity on a weight basis is 2-alkynoic acids greater than 2-alkenoic acids greater than alkanoic acids greater than 2-bromoalkanoic acids greater than 2-fluoroalkanoic acids. There is an inverse relationship between chain length and pKa of the acids, suggesting that partition behavior is a fundamental determinant of fungitoxicity along with the effect of adsorbents.
Thirteen alpha, omega-alkanedicarboxylic acids (C2-C12, C14, and C16) and their dimethyl esters were tested against Aspergillus niger, Trichoderma viride, and Myrothecium verrucaria in Sabourauc dextrose agar at pH 4.0 AND 5.6. Toxicity to Canadida albicans, Trichophyton mentagrophytes, and Mucor mucedo was determined in the same medium at pH 5.6 and 7.0 in the absence and presence of 10% beef serum. The dicarboxylic acids possessed very poor to no antifungal activity against all six fungi. The fungitoxicity of the dimethyl esters to A. niger, T. viride, and M. verrucaria was C8 = C9 greater than C7 greater than C6 = C5 greater than C10 greater than C4 greater than C11 and to C. albicans, T. mentagrophytes, and M. mucedo C9 greater than C10 greater than C11 greater than C12 = C8 greater than C7 greater than C6 greater than C5 greater than C4 greater than C3. The fungitoxicity of the esters of fatty acids and alpha-omega-alkanedicarboxylic acids was influenced by chain length and not by the pH of the medium or the absence or presence of beef serum.
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