In-vivo Anti-tumor Evaluation of Dihydroartemisinin-Derived Endodisulphide on MNU-induced Liver Cancer in Sprague-Dawley Rats

Aims: The study evaluated the antitumor potentials of a disulphide-substituted derivative of dihydroartemisinin (sDHA) on chemically induced cancer of the liver in Sprague-Dawley rats in comparison with its parent compound, dihydroartemisinin (DHA) and a standard anticancer drug.

Study Design: Animals were divided into seven experimental and three control groups (n=10 per group). Cancer was induced in experimental groups followed by administration of experimental agents, while control groups received either N-methy-N-nitrosourea (MNU), Tween 80 (vehicle) or distilled water alone.

Place and Duration of Study: Study was done in Faculty of Pharmacy, University of Uyo, Nigeria in 2015-2016.

Methodology: MNU (50 mg/kg) was administered intravenously as single dose to induce cancer in experimental groups, followed by oral treatment with sDHA (37.42, 74.83 or 112.25 mg/kg/day), DHA (57.45, 114.89 or 172.34 mg/kg/day) or cyclophosphamide (0.71 mg/kg/day) for 28 days. Positive control group received only MNU, negative control group received only distilled water (0.3 ml/day), while experimental control group received only Tween 30 (0.3 ml/day). Drug treatments commenced 10 days after MNU injection and animals were observed for 52 days after drug treatments and sacrificed. Serum levels of CA-27-29, 8-OHdG and SOD were measured using ELISA method; and using immunohistochemical tissue staining techniques, Bcl-2 and Ki67 protein expressions were analyzed in hepatic cells.

Results: MNU caused elevation (P <.0001) in CA-27-29 and 8-OHdG; and reduction (P<.0001) in SOD. Hepatic cells of MNU alone treated rats demonstrated strong immunoreactivity for Bcl-2 and Ki67 (≥75%). Oral treatments of sDHA or DHA resulted in dose-dependent reductions of MNU-induced CA-27-29 and 8-OHdG elevations (P<.001) but had no effect on SOD. Additionally, MNU induced Bcl-2 and Ki67 positive immunoreactive expressions were reduced to 25-50% by sDHA and DHA; DHA showing greater effect. Cyclophosphamide reversed all the MNU induced toxic effects.

Conclusions: sDHA possesses antitumor activity against liver cancer; has lesser efficacy than DHA, but both drugs are less effective than cyclophosphamide.