"Our data support the notion that hydroxmatairesinol (HMRlignan), and to a greater extent its human metabolite enterolactone, may suppress the growth of prostate cancer cells," said lead researcher Marco Cosentino from the Department of Clinical Medicine at the University of Insubria in Italy.
Lignans have a weak oestrogen-like activity and in humans 7-hydroxymatairesinol is converted into a mammalian lignan called enterolactone. Epidemiological studies have linked enterolactone to a reduced risk of certain hormone-related health conditions including breast cancer and cardiovascular disease.
"Also in view of its well-established tolerability and bioavailability, hydroxmatairesinol represents a viable dietary supplement providing a suitable source for endogenous entrolactone that, in turn, may play a role in the promotion of prostate health," concluded Cosentino.
Over half a million men worldwide are diagnosed with prostate cancer every year, with over 200,000 deaths from the disease.
The new study, which has not been seen by NutraIngredients.com and is yet to be published in a peer-reviewed journal, investigated the effects of enterolactone (70-100 micromoles) or hydroxymatairesinol (70-100 micromoless) on human androgen-dependent prostate cancer cells lines for 48 hours. Estradiol (100 micromoles) and the cytotoxic agent cycloheximide (10 micromoles) were used as the experimental controls.
The results are reported to show that both enterolactone and hydroxymatairesinol increased programmed cell death (apoptosis) in a dose-dependent manner. Enterolactone is said to be two times as effective as hydroxymatairesinol in this experiment but less than half that of cycloheximide and estradiol.
"These results indicate that, in-vitro, the viability of human prostate cancer cells is impaired by the lignans enterolactone and, to a lesser extent, hydroxymatairesinol. The effect is, however, milder than that of an established cytotoxic agent such as cycloheximide," said Cosentino.
Robin Ward, vice president of marketing for Linnea, told NutraIngredients.com: "The study was completed last week and build on the state of the art regarding the pharmacology of lignans and the active metabolite enterolactone."
Cosentino and his researchers propose that the mechanism is likely to be via an oestrogen-like action.
"This is the first study showing the ability of enterolactone and hydroxymatairesinol to modify the intracellular balance between pro- and anti-apoptotic proteins, an action which likely contributes to the overall pro-apoptotic effect of both lignans.
Such an action is, however, exerted at concentrations that are several tenfold lower than those affecting cell viability, suggesting that additional mechanisms are involved in the final pro-apoptotic effect," said Cosentino.
Since obtaining the rights to commercialise the HMRlignan in early 2005, the company has been active in sponsoring studies for different health conditions, including the menopause, bone health, heart health, and protection against breast and prostate cancer.
"The results provide data that supports the hypothesis that lignans support prostate health. The the next step is an animal model looking at the capacity of HMRlignan to reduce prostate size. The eventual target is a human study looking at capacity of Norwegian spruce lignans to address the urological symptomology of BPH [benign prostate hyperplasia]," said Ward.