Anticancer Activity and Phytochemicals Analysis of Eucalyptus species in Bangladesh

Abstract

An attempt has been made in this dissertation to find out potential chemo-preventive drugs for effective therapeutic management of cancers. For this purpose, anticancer activity of methanol extract (ME), petroleum ether extract (PEE) and ethyl acetate extract (EAE) of Eucalyptus camaldulensis has been studied out against Ehrlich ascites carcinoma (EAC) cells in mice with three different doses (25.0, 50.0 and 100.0 mg/kg/day; i.p.). The study has been done by monitoring the parameters like tumor weight measurement, survival time of tumor bearing mice, growth inhibition of cancer cells, hematological profile, transplant ability of tumor cells etc. All the extracts showed remarkable anticancer properties. Among them, EAE exhibited the highest activity at the dose of 100 mg/kg/day (i.p.). It showed 96 % (P < 0.001) cell growth inhibition and reduced tumor burden significantly (81.4 %; P < 0.01) when compared with the control. It also increased the life span of EAC bearing mice pronouncedly (71.36 %; P < 0.01). It restored the altered hematological parameters more or less towards normal levels. On the other hand, ME and PEE showed 71.72 % (P < 0.01) and 85 % (P < 0.001) cell growth inhibition respectively at the same dose. They also showed potential resistance in tumor burden and increased the life span of tumor bearing mice remarkably. EAE showed its resistance to EAC cells by inducing apoptosis as investigated by observing morphological changes of EAC cells treated with EAE under fluorescence microscope. EAC cells treated with EAE showed membrane blabbing, chromatin condensation, nuclear fragmentation (apoptotic feature) in Hoechst 33342 staining. DNA fragmentation assay in agarose gel (1.5%) electrophoresis also reflected the apoptotic death of EAC cells following EAE treatment. Apoptosis of EAC cells treated with EAE is induced by caspase-3 mediated signaling pathway, which was observed from cellular growth in presence of caspase-3 and caspase-8 inhibitors. Caspase-8 inhibitor (caspase-8 blocked and caspase-3 active) pretreated EAC cells showed 67% (p<0.01) cell growth inhibition with EAE in comparison with that of control whereas caspase-3 inhibitor (caspase-3 blocked and caspase-8 active) did not show any such effect. Biochemical and hematological parameters as well as histopathological observations of major organs of mice receiving the extracts did not show any major or minor toxicity at the dose used in this studies. Experimental results obtained from EAE extract of Eucalyptus exhibited the potential anticancer activity through apoptosis. Thus it can be considered as one of the promising resource of chemotherapeutic drugs. The EAE was fractionated by column chromatography from which only one compound (p-menth-1-ene-4,7-diol) was isolated. Probably this compound is responsible for the anticancer activity of EAE but this assumption has not been verified here.