Introduction and objective:
Breast cancer is the most common type of tumour in terms of incidence and mortality among women. In the light of recent data that has revealed the beneficial impact of increasing plant-based food consumption on the risk of breast cancer, the use of young green barley and chlorella, the chemopreventive properties of which have been previously reported, seems to be a reasonable therapeutic strategy in this type of cancer. Nevertheless, there are only a few scientific reports focused on the influence of the mentioned products on breast cancer development; thus, the aim of the study was to enrich knowledge resources in this area.

Material and methods:
The chemopreventive effect of water extracts of chlorella (CH) and young green barley (YGB) and their mixture (MIX) was investigated in human breast adenocarcinoma T47D cells and human skin fibroblasts HSF by LDH, MTT and BrdU assays. Changes in cell morphology in response to tested extracts were examined in light microscopy.

Results:
Tested extracts were not toxic against HSF and did not affect their proliferation and morphology. Simultaneously, extracts increased the permeability of T47D cell membranes and inhibited their proliferation. Microscopic observation confirmed the results of biochemical assays and additionally suggested necrosis induction in T47D cells in response to tested compounds. Obtained results demonstrated that MIX induced stronger beneficial changes than their components.

Conclusions:
The study revealed the chemopreventive properties of the investigated green food products against breast cancer cells, without any side-effects in human skin fibroblasts. The beneficial properties discovered of the tested extracts on cancer cells enhanced by their concomitant administration, and in the case of antiproliferative effects YGB and CH, revealed synergism of action.