Protective Effect of Caffeic Acid Phenethyl Ester on Antituberculosis Drug-Induced Hepatotoxicity in Rats

Tuberculosis is a serious disease and is difficult to treat because of its resistance to drugs and long-term treatment period as well as its tendency to increase in diseases, such as HIV, along with patient compliance. Asymptomatic increases in transaminase are common during antituberculosis treatment, but hepatotoxicity can cause mortality when not noticed early and when therapy is not ceased in time. Isoniazid (INH) is a drug that is commonly used in the treatment of active and latent Mycobacterium tuberculosis infections. Rifampicin (RIF) is another primary component for the treatment and prophylaxis of tuberculosis. Both drugs are metabolized by the liver.¹ Isoniazid and rifampicin are potentially hepatotoxic drugs.² This hepatotoxicity mostly happens through oxidative stress.³ Caffeic acid phenethyl ester (CAPE) is an active ingredient of honeybee propolis extract that has been used as a traditional medicine in the Far East.⁴ The molecular weight and empirical formula of CAPE are 284.3 g/mol and C₁₇H₁₆O_4.⁵ CAPE has no potentially harmful effects on normal cells.⁶ It is a small, flavonoid-like, lipid soluble compound that has anti-inflammatory,⁷ antiviral, anticarcinogenic, immunomodulatory,⁸ and antioxidant activities.⁹ It has been shown that CAPE suppresses lipid peroxidation, inhibits lipoxygenase activities and tumor promotion, lipid peroxidation, lipoxygenase activities, protein tyrosine kinase, and ornithine decarboxylase.¹⁰ Korish et al¹¹ pointed out that CAPE creates hopeful results on correcting acute liver failure by affecting oxidative stress and disordered hemostasis. CAPE can prevent radiation induced liver cell apoptosis.¹² Zinc (Zn) is a trace element with anti-inflammatory and anti-apoptotic effects along with important antioxidant properties. In experimental animal models, although it was not fully clarified, it has been seen that zinc has hepatoprotective properties on acute and chronic liver damage.¹³ Copper (Cu) is a trace element, acting as a cofactor in many enzymatic reactions.¹⁴ Excessive copper build up in the liver has been reported in primary biliary cirrhosis, alcoholic cirrhosis, and other cholestatic syndromes.^15,16 All these studies show that extensive research is necessary for recognizing biochemical analysis and for healing liver damage, which can develop during antituberculosis drug treatment, primarily INH and RIF. Tuberculosis disease still remains a major health problem. When patients are having tuberculosis treatment they may be required emergency surgery. Therefore, our aim in this study is to investigate the protective effects of CAPE on liver function tests and trace elements on the hepatic damage caused by INH and RIF on rats.

Materials and Methods

Statistical Analysis

Statistical analysis was performed using SPSS for Windows 11.5 (SPSS Inc, Chicago, Illinois). Data were expressed as mean ± SD (standard deviation) values for biochemical values. Groups were compared using the nonparametric Kruskal-Wallis test. Mann-Whitney U test was used for binary comparisons. A P-value of less than 0.05 was considered significant.

Results

All animals survived throughout the experimental procedures. The liver functions, serum Cu and Zn levels of all groups are shown in Table 1. Serum TAC, TOS, and OSI levels are shown in Table 2. Comparisons of the serum Cu and Zn levels between the groups are shown in Fig. 1. Serum ALT, AST, Cu, and TOS levels were found to be significantly higher in Group 3 compared to the other 3 groups (P < 0.05). When Group 1 and Group 2 were compared, serum Zn values were found to be higher in Group 2 (P = 0.029). There was no difference in the other parameters between the 2 groups (P > 0.05). When Group 1 and Group 4 were compared, differences between their TOS and OSI levels were detected (P < 0.05). Other parameters were the same (P > 0.05). There were significant differences between all parameters when Group 2 and Group 3 were compared (P < 0.001). When Group 2 and Group 4 were compared, Zn, TOS, and OSI levels were different (P < 0.05). All parameters were significantly different when Group 3 and Group 4 were compared (P < 0.05).

Table 1  Serum ALT, AST levels (mg/dL) and Zn, Cu levels (μm/protein)

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Table 2  Oxidative and antioxidative parameters in groups

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Discussion

Antituberculosis drug-induced hepatotoxicity causes substantial morbidity and mortality and decreases treatment effectiveness.¹ Adverse effects significantly contribute to nonadherence, eventually contributing to treatment failure, relapse, or the emergence of drug-resistance. Consequently, they diminish treatment effectiveness.^19,20 Numerous studies have demonstrated that oxidative damage is an important mechanism of antituberculosis drug-induced hepatotoxicity.^21–23 Isoniazid can cause mild to moderate elevation of plasma liver enzyme activity in 10% to 20% of patients and severe hepatotoxicity in approximately 0.5% to 2%²⁴ of patients. It has been reported that the incidence of hepatotoxicity is approximately 2.6% with isoniazid–rifampin co-administration, but only 1.6% with isoniazid treatment alone and 1.1% with rifampin alone. This suggests that there is higher incidence of severe hepatotoxicity in patients cotreated with these 2 drugs.²⁵ CAPE is a natural flavonoid-like compound that has protective effects against drug-induced hepatotoxicity.²⁶ Ashwag et al detected that CAPE decreases liver damage by increasing antioxidant capacity in tamoxifen-induced hepatotoxicity.²⁷ Kart et al found in a study that CAPE has a protective property in cisplatin-induced hepatotoxicity and that this was related to its antioxidant property.²⁸ In our study, when the control group and the INH + RIF group were compared, it was found that in the INH + RIF group, rats had a lower TAC value (P = 0.001) and higher OSI and TOS values (P < 0.001). Furthermore, when the 2 groups were compared, we saw that the AST and ALT values were higher in the INH + RIF group of rats (P < 0.001). These results show that INH and RIF, which have been commonly used for a long time in tuberculosis treatment, can increase liver damage by elevating oxidative stress. In several experimental animal models, it has been shown that changes in the Cu and Zn levels in the liver tissue affect liver damage.^29,30 In addition, it has been shown that increasing Cu and decreasing Zn levels are related to oxidative stress.³¹ In our study, we saw that when the group that were only given CAPE and the group given INH + RIF were compared, the serum Zn levels of the CAPE group rats were elevated (P < 0.001) and the Cu levels were decreased (P < 0.001). By comparing these 2 groups, we determined that the TAC levels were higher (P < 0.001) and the TOS and OSI levels were lower (P < 0.001) in the CAPE group. Furthermore, the AST and ALT levels were significantly higher in the INF + RIF group (P < 0.001). These results show that CAPE can affect liver damage. Albukhari et al²⁷ determined in a study that antioxidant enzyme levels were higher and oxidative status was lower in CAPE + tamoxifen rats when compared to tamoxifen only rats; therefore, liver enzyme levels were lower. Kart et al²⁸ compared rats that were given cisplatin with rats that were given CAPE + cisplatin and found that in the CAPE + cisplatin group, liver enzymes were lower. Lee et al³² compared rats that were given t-BHP to CAPE + t-BHP and saw that the second group had less oxidative stress. Our study also showed elevated Zn levels (P = 0.001) and decreased Cu levels (P = 0.019) in the INH + RIF + CAPE group when compared to the INH + RIF group. Again, when we compared these 2 groups, we determined that TAC increased in the INH + RIF + CAPE group and the TOS and OSI decreased (P < 0.001). Furthermore, in the INH + RIF + CAPE group, the AST and ALT values were lower (P < 0.001).

Conclusion

The results of this study showed that INH + RIF, important drugs in antituberculosis treatment, increased oxidative damage and elevated liver enzymes. When CAPE was added to the treatment, Zn levels increased and Cu levels decreased. Furthermore, oxidative stress also decreased. As a result of all this, we detected a significant correction in liver enzymes. As a conclusion, we determined that CAPE decreases liver damage. This situation may be associated with changes in the levels of Zn and Cu. Additional studies are needed to clarify this situation.