Cytotoxic and antiviral activities of Magnolia grandiflora L. leaves growing in Egypt

Abstract

Magnolia grandiflora L. (Magnoliaceae), is used in traditional medicine for treatment of fever, diarrhea, rheuma and arthritis. A number of biologically active alkaloids, sesquiterpenes, phenolics and neolignans have been isolated from this species. Bioassay guided fractionation of a methanol extract of Magnolia grandiflora L. leaves led to isolation and characterization of four aporphine alkaloids, magnoflorine, lanuginosine, liriodenine and anonaine. The structure of these compounds was determined on the basis of spectroscopic studies. The Cytotoxicity of the pure compounds magnoflorine and lanuginosine were determined in tumor cell lines, Hela (cervix tumor cell line), HEPG2 (hepatocellular carcinoma cell line) and U251 (brain tumor cell line). The cell viability tests were performed as described previously (1). Magnoflorine and lanuginosine displayed a significant activity in the in vitro cytotoxic assay against (HEPG2) cancer cell line. Magnoflorine was more cytotoxic (IC50 0.4µg/ml) than lanuginosine (IC50 2.5µg/ml) against HEPG2 in comparison with the standard doxorubacin (IC50 0.27µg/ml). In addition, magnoflorine and lanuginosine exhibited cytotoxicity against brain tumor cell line U251 with IC50 7µg/ml and 4µg/ml respectively. The two compounds were found to have no cytotoxic activity against Hela cancer cells. On the other hand, the antiviral activity of the methanol extract was investigated against two viruses: Herpes simplex virus type -1 (HSV-1) and Poliovirus type-1 (PV-1) using Plaque reduction assay (2). The activity was calculated by percentage of viral plaque inhibition at non-cytotoxic concentrations of the extract. Methanol extract showed high antiviral activity against herpes simplex virus (HSV-1) (83.7%) inhibition at 2.2µg/ml whereas the extract exhibited a moderate antiviral activity against Poliovirus type-1 (47%) inhibition at 1.1µg/ml. In conclusion, magnoflorine and lanuginosine might be valuable antitumor promoting agents and the methanol extract exhibited potent anti-viral activity against HSV-1 virus that can be exploited for development of an alternative remedy for HSV-1 infection.