Eva Sidóová

Benzothiazole Derivatives. 48. Synthesis of 3-Alkoxycarbonylmethyl-6-bromo-2-benzothiazolones and 3-Alkoxycarbonylmethyl-6-nitro-2-benzothiazolones as Potential Plant Growth Regulators

Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University, Mlynska Dolina,SK - 842 15 Bratislava, Slovakia.*Author to whom correspondence should be addressed.Received: 17 March 1998 / Accepted: 8 March 1999 / Published: 26 March 1999Abstract: 3-Alkoxycarbonylmethyl-6-bromo- and 3-alkoxycarbonylmethyl-6-nitro-2-benzo-thiazolones were synthesized by reaction of alkylesters of halogenoacetic acids with 6-bromo-2-benzothiazolones and 6-nitro-2-benzothiazolones respectively. The compoundswere tested for plant growth stimulating activity on wheat ( Triticum aestivum ). The bromoderivatives manifested 25.4 % average stimulating activity in comparison with the control.The stimulation activity of the nitro derivatives was not significant. Optimal structures of thecompounds were obtained by a MMPI method, atomic charges and dipole moments werecalculated by a semiempirical AM1 method. On the basis of molecular electrostatic potentialit has been found that the biological activity of synthesized compounds depends on chargedistribution in the molecules.Keywords: 3-Alkoxycarbonylmethyl-6-bromo-2-benzothiazolones, 3-alkoxycarbonyl-methyl-6-nitro-2-benzothiazolones, plant growth regulators, AM1 calculations, lipophilicity.

3-(2-Alkylsulfanyl-6-benzothiazolylaminomethyl)-2-benzoxazolethiones - Synthesis and Photosynthesis-Inhibiting Activity in Spinach Chloropasts

Eva Sidoova, Katarina Kralova and Dusan Loos*Institute of Chemistry, Faculty of Natural Sciences, Comenius University, Mlynska dolina CH-2, SK-842 15 Bratislava, Slovakia. Tel. +421 7 60296342, Fax +421 7 65429064, E-mail loos@fns.uniba.sk*Author to whom correspondence should be addressed.Received: 12 May 1998 / Accepted: 5 March 1999 / Published: 29 March 1999Abstract: The synthesis and photosynthesis-inhibiting activity of 14 new 3-(2-alkylsulfanyl-6-benzothiazolylaminomethyl)-2-benzoxazolethiones are reported. The new compounds wereprepared by the reaction of 2-alkylsulfanyl-6-aminobenzothiazoles with 3-hydroxymethyl-2-benzoxazolethione. The structures of the compounds were verified by

Inhibition of yeast-mycelium transformation by 2-alkylthio-6-amino-and 2-alkylthio-6-formamidobenzothiazoles and theirin vitro antifungal activity

The antifungal effect of 2-alkylthio-6-amino-and 2-alkylthio-6-formamidobenzothiazoles (22 derivatives in all) onAspergillus niger and variousCandida yeasts was tested. No significant effect was observed withA. niger. With the pathogenic yeast speciesC. albicans andC. guilliermondii, the most efficient derivatives (6-formamido-2-propylthio-, 6-formamido-2-butylthio-, 6-formamido-2-pentylthio-and 6-formamido-2-isopentylthiobenzothiazole) exhibited ED50 values in the range from 2.2 to 21 mg/L and were thus 3–35 times more efficient than 2-mercaptobenzothiazole (Dermacid) that is normally used. 6-Amino-2-pentylthiobenzothiazole was found to be an efficient specific inhibitor of the transformation of the yeast form ofC. albicans to its mycelial one, IC95(M) being 10 mg/L, which was a concentration 25 times lower than MICY+M.

Synthesis of 2-(6-Acetamidobenzothiazolethio)acetic Acid Esters as Photosynthesis Inhibitors

The synthesis and photosynthesis-inhibiting activity of 13 new 2-(6-acetamidobenzothiazolethio)acetic acid esters are reported. The new compounds were prepared by acetylation of 2-(alkoxycarbonylmethylthio)-6-aminobenzothiazoles with acetic anhydride. The structure of the compounds was verified by 1H NMR spectra. The compounds inhibit photosynthetic electron transfer in spinach chloroplasts. The structure - activity relation was studied. Lipophilicity was found to influence substantially photosynthetic electron transfer.

Efficacy of 6-amino-2-n-pentylthiobenzothiazole onTrichophyton in vitro and in vivo

In vitro and in vivo antifungal activities of synthetically parepared 6-animo-2-n-pentylthiobenzothiazole (APB) againstTrichophyton strains were studied. APB inhibited the growth of 3Trichophyton strains at 65 µg/ml. 2-Mercaptobenzothiazole was not effective at 125 µg/ml and ketoconazole inhibited the growth at 20–30 µg/ml. Treatment of experimental dermatophytosis in guinea pigs using 2.5% APB cream was studied in comparison to Canesten cream (1% clotrimazole). Dermatophytosis was considerably reduced after both APB and Canesten therapies.