The Protective Effect of Combined Leaf Extracts of Gongronema latifolium and Nauclea latifolia on Acetaminophen-induced Liver Toxicity in Rats

Aims: Protective effects of the combined ethanolic leaf extracts of Gongronema latifolium (GL) and Nauclea latifolia (NL) on acetaminophen-induced liver toxicity were studied in rats in comparison with individual extract treatment and the standard drug; Silymarin.
Study Design: The design consisted of sixty rats divided into ten groups of six rats each. Hepatotoxicity was induced orally with a single dose of acetaminophen (200mg/kg, bw, p.o,) diluted with sucrose solution (40% w/v) in five groups. Animals were then separated into five hepatotoxic and five non-hepatotoxic groups and treated with GL, NL, GL+NL, Silymarin or distilled water.
Place and Duration of Study: Department of Biochemistry, Faculty of Basic Medical Sciences, University of Calabar, Nigeria, between February, 2010 to August, 2011.
Methodology: The phytochemical constituents of Nauclea latifolia (NL) and Gongronema latifolium (GL) leaf extracts were determined quantitatively using standard methods. The pharmacological studies involves ten groups of six rats each; divided into five hepatotoxic and five non-hepatotoxic groups and then treated with the extracts, silymarin or distilled water. Biochemical indices (protein, albumin, AST, ALT) as well as antioxidant enzymes like catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase(SOD) and histological examinations were done with the serum and liver respectively.
Results: The quantitative phytochemical investigations of the NL and GL leaf extract showed the content of alkaloids, polyphenols, flavonoids, saponins and hydrocyanic acid. Administration of only toxicant showed that the ALT and AST levels were significantly (P=.05) increased by 3.19 and 3.01 fold respectively while the levels of total protein and albumin were decreased when compared to the normal control. Pretreatment with extracts both singly and in combination for 21 days decreased the elevated levels of the transaminases and restored the normalcy of total protein and albumin significantly. These were most impacted in the combined extract treatment group, indicating a positive synergy. In only acetaminophen treated rats, CAT (441.47±130.95), GPx (2720.27±33.78) and SOD (13.52±0.21) were decreased significantly but treatment with extracts of GL (CAT= 531.37±27.60, GPx=2768.51±19.78 & SOD=15.05±0.35) or NL (CAT=475.20±50.13, GPx=3307.26±343.69 & SOD=13.69±0.41) and in combination (CAT= 785.40±74.46, GPx=4449.59±26.48 & SOD=15.69±0.60) caused a significant increase (P=.05) in these antioxidants activities. Acetaminophen treatment alone showed severe liver damage while pretreatment with only NL or GL showed an improvement in histological section of the liver but the protective effect was more pronounced in the combined extract treatment group against the hepatocellular damage.
Conclusion: These results suggested that NL and GL leaf extracts have a significant role in alleviating liver damage, with the combined extracts synergistically improving the levels of these indices more, thus suggesting a better amelioration of hepatotoxicity.