The aim of this study was to evaluate the potential anticancer properties and modulatory effect of selected Aloe vera (A. vera) active principles on
antioxidant enzyme activities. Thus, three
anthraquinones (Namely:
aloesin,
aloe-emodin and
barbaloin) were extracted from A. vera leaves by supercritical fluid extraction and subsequently purified by high performance liquid chromatography. Additionally, the N-terminal octapeptide derived from verectin, a biologically active 14 kDa
glycoprotein present in A. vera, was also tested. In vivo, active principles exhibited significant prolongation of the life span of
tumor-transplanted animals in the following order:
barbaloin> octapeptide>
aloesin >
aloe-emodin. A. vera active principles exhibited significant inhibition on Ehrlich ascite
carcinoma cell (EACC) number, when compared to positive control group, in the following order:
barbaloin>
aloe-emodin > octapeptide >
aloesin. Moreover, in
trypan blue cell viability assay, active principles showed a significant concentration-dependent cytotoxicity against
acute myeloid leukemia (AML) and acute lymphocytes
leukemia (ALL) cancerous cells. Furthermore, in MTT cell viability test,
aloe-emodin was found to be active against two human
colon cancer cell lines (i.e. DLD-1 and HT2), with IC(50) values of 8.94 and 10.78 microM, respectively. Treatments of human AML leukemic cells with active principles (100 microg ml(-1)) resulted in varying intensities of internucleosomal DNA fragmentation, hallmark of cells undergoing apoptosis, in the following order:
aloe-emodin>
aloesin>
barbaloin> octapeptide. Intererstingly, treatment of EACC
tumors with active principles resulted in a significant elevation activity of key
antioxidant enzymes (SOD, GST, tGPx, and LDH). Our data suggest that the tested A. vera compounds may exert their chemo-preventive effect through modulating
antioxidant and detoxification
enzyme activity levels, as they are one of the indicators of
tumorigenesis. These findings are discussed in the light of the potential of A. vera
plant extracts for developing efficient, specific and non-toxic anticancer drugs that are affordable for developing countries.