Isopropyl Caffeate: A Caffeic Acid Derivative-Antioxidant Potential and Toxicity

Abstract

Phenolic compounds, among them isopropyl caffeate, possess antioxidant potential, but not without toxicity and/or adverse effects. The present study aimed to evaluate the antioxidant activity and toxicity of isopropyl caffeate through in silico, in vitro and in vivo testing. The results showed that isopropyl caffeate presents no significant theoretical risk of toxicity, with likely moderate bioactivity: GPCR binding, ion channel modulation, nuclear receptor binding, and enzyme inhibition. Isopropyl caffeate induced hemolysis only at the concentrations of 500 and 1000 μg/ml. We observed types A and O erythrocyte protection from osmotic stress, no oxidation of erythrocytes, and even sequestrator and antioxidant behavior. However, moderate toxicity, according to the classification of GHS, was demonstrated through depressant effects on the central nervous system, though there was no influence on water and food consumption or on weight gain, and it did present possible hepatoprotection. We conclude that the effects induced by isopropyl caffeate are due to its antioxidant activity, capable of preventing production of free radicals and oxidative stress, a promising molecule with pharmacological potential.

Figure 1

Isopropyl caffeate.

Figure 2

Hemolytic evaluation in type A erythrocytes, as induced by isopropyl caffeate. The results are expressed as mean ± SD analysis by ANOVA followed by Dunnett's test, ^∗p < 0.05 (n = 3).

Figure 3

Hemolytic evaluation in type B erythrocytes, as induced by isopropyl caffeate. The results are expressed as mean ± SD analysis by ANOVA followed by Dunnett's test, ^∗p < 0.05 (n = 3).

Figure 4

Hemolytic evaluation in type O erythrocytes, as induced by isopropyl caffeate. The results are expressed as mean ± SD analysis by ANOVA followed by Dunnett's test, ^∗p < 0.05 (n = 3).

Figure 5

Hemolytic evaluation in type AB erythrocytes, as induced by isopropyl caffeate. The results are expressed as mean ± SD analysis by ANOVA followed by Dunnett's test, ^∗p < 0.05 (n = 3).

Figure 6

Antihemolytic evaluation in erythrocytes type A, induced by isopropyl caffeate, when in a hypotonic solution (NaCl 0.24%). The results are expressed as mean ± SD analysis by ANOVA followed by post-Dunnett's test, ^∗p < 0.05 (n = 3).

Figure 7

Antihemolytic evaluation in type B erythrocytes, as induced by isopropyl caffeate, when in a hypotonic solution (NaCl 0.24%). The results are expressed as mean ± SD analysis by ANOVA followed by Dunnett's test, ^∗p < 0.05 (n = 3).

Figure 8

Antihemolytic evaluation in type O erythrocytes, as induced by isopropyl caffeate, when in a hypotonic solution (NaCl 0.24%). The results are expressed as mean ± SD analysis by ANOVA followed by Dunnett's test, ^∗p < 0.05 (n = 3).

Figure 9

Antihemolytic evaluation in type AB erythrocytes, induced by isopropyl caffeate, when in a hypotonic solution (NaCl 0.24%). The results are expressed as mean ± SD analysis by ANOVA followed by Dunnett's test, ^∗p < 0.05 (n = 3).

Figure 10

Oxidizing and antioxidant effects of isopropyl caffeate in human erythrocytes. The results are expressed as a percentage of average of formation of methemoglobin (MetHb) compared to the negative control group (oxidant test) and a positive control (antioxidant test). The results are expressed as mean ± SD analysis by ANOVA followed by Dunnett's test, ^∗p < 0.05 (n = 3).

Figure 11

Antioxidant activity of isopropyl caffeate against hemolysis induced by hydrogen peroxide in blood type O. Results are expressed as a percentage of average in comparison to the positive control group (Hb + H₂O₂). The results are expressed as mean ± SD analysis by ANOVA followed by Dunnett's test, ^∗p < 0.05 (n = 3).

Figure 12

Dosage of malondialdehyde (MDA) of liver homogenate of Balb/c females submitted to administration of isopropyl caffeate. The results are expressed as mean ± SD analysis by ANOVA followed by Dunnett's test, ^∗p < 0.05 (control and dose of 300 mg/kg, n = 6/dose of 2000 mg/kg, n = 4).

Figure 13

Determination of NO in liver homogenate of Balb/c females submitted to administration of isopropyl caffeate. The results are expressed as mean ± SD analysis by ANOVA followed by Dunnett's test, ^∗p < 0.05 (control and dose of 300 mg/kg, n = 6/dose of 2000 mg/kg, n = 4).

Figure 14

Spleen of treated Balb/c females V.O., stained with hematoxylin and eosin (increase 200x), there was no sign of toxicity in the spleen. Asterisks appoint red pulp and white flesh (#) without special histological features. (a) Control group vehicle. (b) Group treated with a dose of 300 mg/kg. (c) Group treated with a dose of 2000 mg/kg.

Figure 15

Liver of treated Balb/c females V.O., stained with hematoxylin and eosin (increase 200x), there was no sign of toxicity in the liver. The arrows appoint portal spaces and the asterisks appoint normal hepatocytes. (a) Control group vehicle. (b) Group treated with a dose of 300 mg/kg. (c) Group treated with a dose of 2000 mg/kg. (d) Animal treated with a dose of 2000 mg/kg with little inflammatory infiltrate portal (portal spaces (arrow) with mild chronic inflammatory infiltration). (e) Animal treated with a dose of 2000 mg/kg (portal spaces (arrow) with moderate chronic inflammatory infiltration).

Figure 16

Stomach of treated Balb/c females V.O., stained with hematoxylin and eosin (increase 200x), there was no sign of toxicity in the stomach. The arrow appoints normal gastric mucosa. (a) Control group vehicle. (b) Group treated with a dose at 300 mg/kg. (c) Group treated with a dose of 2000 mg/kg.