Anticancer and Antiphytopathogenic Activity of Fluorinated Isatins and Their Water-Soluble Hydrazone Derivatives

Abstract

A series of new fluorinated 1-benzylisatins was synthesized in high yields via a simple one-pot procedure in order to explore the possible effect of ortho-fluoro (3a), chloro (3b), or bis-fluoro (3d) substitution on the biological activity of this pharmacophore. Furthermore, the new isatins could be converted into water-soluble isatin-3-hydrazones using their acid-catalyzed reaction with Girard's reagent P and its dimethyl analog. The cytotoxic action of these substances is associated with the induction of apoptosis caused by mitochondrial membrane dissipation and stimulated reactive oxygen species production in tumor cells. In addition, compounds 3a and 3b exhibit platelet antiaggregation activity at the level of acetylsalicylic acid, and the whole series of fluorine-containing isatins does not adversely affect the hemostasis system as a whole. Among the new water-soluble pyridinium isatin-3-acylhydrazones, compounds 7c and 5c,e exhibit the highest antagonistic effect against phytopathogens of bacterial and fungal origin and can be considered useful leads for combating plant diseases.

Keywords: antiphytopathogenes; cancer; crystal structure; cytotoxicity; hydrazones; isatin; quaternary ammonium compounds.

Figure 1

Fluorinated isatin derivatives exhibit various types of biological activity.

Figure 2

Isatin-3-acylhydrazones possess antimicrobial activity.

Scheme 1

Two-step one-pot synthesis of polyfluorinated 1-benzylisatins.

Scheme 2

Synthesis of 5-fluorinated 1-alkylbenzylisatins.

Figure 3

Previously published [26] fluorinated dimethylpyridinium isatin hydrazones.

Scheme 3

Synthesis of fluorine-containing pyridinium isatin hydrazones.

Figure 4

X-ray geometry of fluorinated isatins 3f (A) and 4c (B) in the crystals. Ellipsoids are shown with a 50% probability.

Figure 5

Different biological activity profiles of fluorinated isatin derivatives.

Figure 6

Previously published fluoroisatins are under investigation.

Figure 7

(a) Apoptosis induction in HuTu 80 cells incubated with compounds 3a, 3b, and 3d at IC₅₀/2 and IC₅₀ concentrations. (b) Values are presented as mean ± standard deviation (in triplicate), L—live cells; D—dead cells; Ea—cells in early apoptosis; La—cells in late apoptosis; and PI—propidium iodide. ****—p < 0.0001 versus control. The statistical analysis was performed using a two-way ANOVA and the Bonferroni test.

Figure 8

(a) Effects of compounds 3a, 3b, and 3d on mitochondrial membrane potential. (b) Quantitative distribution of HuTu 80 cells in % with red aggregates and green monomers. ****—p < 0.0001 versus control. The statistical analysis was performed using a two-way ANOVA and the Bonferroni test.

Figure 9

Induction of ROS production by compounds 3a, 3b, and 3d. The data show a significant dose-dependent increase in CellROX^® Deep Red fluorescence intensity for compounds 3a and 3b. Interestingly, compound 3a showed only a small (1.1-fold) increase in ROS production at 12.5 µM (below its IC₅₀), but the ROS production increased to 7.1 times relative to the control at 25 µM. This indicates a significant dose-dependent increase in ROS production in the presence of this substance. Other substituted isatins 3b and 3d led to increased ROS production relative to the control. **—p < 0.01 and ****—p < 0.0001 versus control. The statistical analysis was performed using a one-way ANOVA and the Dunnett test.

Figure 10

Bactericidal action of compounds 5c, 5d, and 7a–c against X. campestris B-610 (a), Pseudomonas fluorescens EL-2.1 (b), and P. carotovorum subsp. carotovorum MI (c) at C = 1000 µg/mL.

Figure 11

Growth of Fusarium oxysporum IBPPM 543 on agar media fortified with the compounds 7c and 7b (C 20 nmol/mL (a); 5e (C 3 nmol/mL) (b); 5e (C 20 and 30 nmol/mL) (c).