Hepatoprotective and Antioxidant Capacity of Mallotus repandus Ethyl Acetate Stem Extract against d-Galactosamine-Induced Hepatotoxicity in Rats

Abstract

Mallotus repandus (M. repandus) is traditionally used to treat muscle pain, itching, fever, rheumatic arthritis, and a variety of liver disorders. The aim of the present work was to evaluate the hepatoprotective activity and the antioxidant potential of the ethyl acetate stem extract of M. repandus (ESMR) against d-galactosamine (d-GalN)-induced hepatopathy, along with a possible mechanism of action in rats. In vivo hepatoprotective activity of ESMR was examined using d-galactosamine (d-GalN)-induced hepatotoxicity in Sprague-Dawley rats. For this purpose, levels of serum diagnostic markers, activity of hepatic antioxidant enzymes, and liver histo-architecture were employed to assess the protective efficacy of ESMR. Furthermore, the total phenolic, flavonoid, and tannin contents were quantitated, and the antioxidant capacity of the extract was evaluated using different methods such as 2,2'-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO), hydrogen peroxide (H₂O₂), and hydroxyl radical (OH^•) scavenging assays. Intraperitoneal d-GalN injection triggered hepatotoxicity, as shown by the noticeable increase in the serum hepatic marker enzymes, bilirubin content, γ-glutamyl transferase (GGT), total cholesterol (TC), triglycerides (TGs), and malondialdehyde (MDA), whereas glutathione, superoxide dismutase, and catalase levels were significantly lower compared with that of the control. Pretreatment with ESMR reduced the hepatic enzyme levels along with bilirubin, GGT, and MDA compared to the d-GalN-intoxicated group. These results were supported by histopathological studies, where d-galactosamine caused coagulative necrosis, hemorrhage, and inflammation. However, pretreatment with ESMR ameliorated the histo-architectural changes and brought them back to normal. Results also revealed that the total polyphenolic, flavonoid, and tannin content, and total antioxidant capacity of ESMR were 136.30 ± 0.78 mg GAE/g mg, 38.72 ± 0.85 mg QE/g, 75.88 ± 0.54 mg TAE/g, and 123.16 ± 0.24 mg AAE/g, respectively. In addition, ESMR inhibited free radicals with IC₅₀ values of 94.47 ± 0.51, 127.33 ± 0.36, 164.12 ± 0.45, and 254.14 ± 0.35 μg/mL in DPPH, NO, H₂O₂, and OH^• free radical scavenging assays, respectively. These findings highlight the protective role of ESMR against hepatic injury induced by d-GalN, which may be attributed to its higher antioxidant properties, thereby scientifically justifying its traditional use.

Figure 1

Effect of ESMR and silymarin on ALT, AST, and ALP against d-GalN-induced hepatotoxicity (values are mean ± SEM, n = 7. p values: ^# <0.05, ^## <0.01 compared between Group I and Group II, p values: * <0.05, ** <0.01 compared among Group II to Group VI).

Figure 2

Effect of ESMR and silymarin on the total bilirubin level against d-GalN-induced hepatotoxicity [Values are mean ± SEM, n = 7. p values: ^# <0.05, ^## <0.01 compared between Group I and Group II, p values: * <0.05, ** <0.01 compared among Groups II to VI].

Figure 3

Effect of ESMR and silymarin on the GGT level against d-GalN-induced hepatotoxicity. Values are mean ± SEM, n = 7. p values: ^# <0.05, ^## <0.01 compared between Group I and Group II, p values: * <0.05, ** <0.01 compared among Groups II to VI.

Figure 4

Effect of ESMR and silymarin on total protein, albumin, and globulin levels against d-GalN-induced hepatotoxicity. Values are mean ± SEM, n = 7. p values: ^# <0.05, ^## <0.01 compared between Groups I and II, p values: * <0.05, ** <0.01 compared among Groups II to VI.

Figure 5

Effect of ESMR and silymarin on the liver LPO level against d-GalN-induced hepatotoxicity (Values are mean ± SEM, n = 7. p values: ^# <0.05, ^## <0.01 compared between Group I and Group II, p values: * <0.05, ** <0.01 compared among Group II to Group VI).

Figure 6

Effect of ESMR and silymarin on the liver GSH level against d-GalN-induced hepatotoxicity (Values are mean ± SEM, n = 7. p values: ^# <0.05, ^## <0.01 compared between Group I and Group II, p values: * <0.05, ** <0.01 compared among Group II to Group VI).

Figure 7

Effect of ESMR and silymarin on SOD content against d-GalN-induced hepatotoxicity (Values are mean ± SEM, n = 7. p values: ^# <0.05, ^## <0.01 compared between Group I and Group II, p values: * <0.05, ** <0.01 compared among Group II to Group VI).

Figure 8

Effect of ESMR and silymarin on hepatic antioxidant enzyme CAT content against d-GalN-induced hepatotoxicity (Values are mean ± SEM, n = 7. p values: ^# <0.05, ^## <0.01 compared between Group I and Group II, p values: * <0.05, ** <0.01 compared among Group II to Group VI).

Figure 9

Histological examination of liver sections from different groups [(A) Group I: normal arrangement of hepatocytes. (B) Group II: section of liver tissue of d-galactosamine-treated group showing massive coagulative necrosis, hemorrhage, and inflammation. (C) Group III: section of 100 mg/kg silymarin liver tissue pretreated in the liver followed by d-galactosamine, showing preservation of normal hepatocytes. (D) Group IV: section of liver tissue pretreated with 250 mg/kg ESMR followed by d-galactosamine, showing tissue necrosis and inflammation. (E) Group V: section of liver tissue pretreated with 500 mg/kg ESMR followed by d-galactosamine, showing mild inflammation. (F) Group VI: section of liver tissue pretreated with 1000 mg/kg ESMR followed by d-galactosamine, showing normal histology with mild inflammation (100× magnification)].