Consumption of virgin olive oil (VOO) has been associated with a low breast cancer incidence. Pinoresinol is a phytoestrogen that is typically found in VOO. Considering the role of oestrogen in breast cancer development and progression, we investigated the potential antitumor activity of pinoresinol in breast cancer cells. To address this question, we treated MDA-MB-231 (oestrogen receptor [ER] negative) and MCF7 (ER+) human breast tumour cells and MCF10A human mammary epithelial cells (ER-) with different concentrations of pinoresinol. The cytotoxic activity, cell proliferation, cell cycle profile, apoptosis induction, reactive oxygen species production and DNA damage were assessed. Pinoresinol showed cytotoxic, anti-proliferative and pro-oxidant activity in human breast tumour cells, independent of their oestrogen receptor status. In addition, pinoresinol exerted antioxidant activity and prevented DNA damage associated with oxidative stress in human mammary epithelial cells. Overall, the results suggest that pinoresinol may have antitumor activity in human breast cancer cells independently of oestrogen receptor status. Furthermore, the results show that the pinoresinol has the typical characteristics of a chemopreventive compound.

Anti‐inflammatory effects of virgin olive oil (VOO) have been described recently, along with its wound healing effect. One of the main minor compounds found in VOO is squalene (SQ), which also possesses preventive effects against skin damage and anti‐inflammatory properties. The inflammatory response is involved in wound healing and manages the whole process by macrophages, among others, as the main innate cells with a critical role in the promotion and resolution of inflammation for tissue repair. Because of that, this work is claimed to describe the role that squalene exerts in the immunomodulation of M1 proinflammatory macrophages, which are the first cells implicate in recent injuries. Pro‐ and anti‐inflammatory cytokines were analysed using TPH1 cell experimental model. SQ induced an increase in the synthesis of anti‐inflammatory cytokines, such as IL‐10, IL‐13, and IL‐4, and a decrease in proinflammatory signals, such as TNF‐α and NF‐κB in M1 proinflammatory macrophages. Furthermore, SQ enhanced remodelling and repairing signals (TIMP‐2) and recruitment signals of eosinophils and neutrophils, responsible for phagocytosis processes. These results suggest that SQ is able to promote wound healing by driving macrophage response in inflammation. Therefore, squalene could be useful at the resolution stage of wound healing.

Oleanolic acid (AO) and maslinic acid (MA) are constituents of the skins of different fruits, including olives and white or red grapes. Although both compounds are known to have beneficial properties against different types of cancers, thus far, there are no studies about their chemopreventive effects in human breast cancer. Thus, we sought to elucidate whether both compounds possess chemopreventive activity. Two cell lines of human breast cancer cells and one noncancerous human mammary epithelial cells were used to determine the effects of OA and MA. The results showed that OA inhibited the proliferation and increased the oxidative stress of highly invasive cells. Additionally, OA decreased oxidative stress and oxidative damage to the DNA in human mammary epithelial cells. These results suggest that OA could act as a chemopreventive agent in human breast cancer and could inhibit the proliferation of highly invasive breast cancer cells.

Uvaol (UV) and erythrodiol (ER) are two triterpenic dialcohols present in the minor fraction of virgin olive oil, in leaves and in the skin and drupe of olives.