Evaluation of cysteine-stabilised peptide fraction of aqueous extract of Morinda lucida leaf for hepatotoxic effects in mice

Abstract

Cysteine-stabilised peptide fraction of the aqueous extract of Morinda lucida leaf has been reported to exert diverse biological activities, but its effects on the liver have not been evaluated. This study was carried out to evaluate the effects of cysteine-stabilised peptide fraction (CSPF) of aqueous extract of Morinda lucida leaf on selected liver function indices in mice. Sixty mice were randomly divided into six groups of ten mice each. Mice in group A (control) were orally administered 5% DMSO while mice in groups B, C, D, E and F were orally administered 31.25, 62.5, 125, 250 and 500 mg/kg body weight of CSPF respectively. Half of the mice in the groups received the respective doses of CSPF for 7 days while the other half received them for 28 days, after which selected liver function indices in the serum and liver of the mice were determined. The results revealed that plasma alkaline phosphatase, gamma glutamyl transferase and glutamate dehydrogenase activities and plasma albumin, globulin, total bilirubin and conjugated bilirubin concentrations were not significantly (P>0.05) altered after 7 and 28 days of CSPF administration at all doses compared to controls. However, liver alanine aminotransferase (ALT) activity was significantly reduced (p<0.05) at doses of CSPF higher than 125 mg/kg body weight, with no corresponding alteration in serum ALT activity after 28 days of administration compared to controls. Thus, prolonged administration of high doses of CSPF may adversely affect the glucose-alanine cycle in the liver which is very important for glucose homeostasis during fasting.