Argan oil's effect on prostate cancer

Tocopherols and Saponins Derived from Argania spinosa Exert, an Antiproliferative Effect on Human Prostate Cancer

By A. Drissi Ph.D. H. Bennani, Ph.D., F. Giton, M.Sc., Z. Charrouf, Ph.D., J. Fiet, M.D., and A. Adlouni, Ph.D.

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Argan tree compounds also can be an important dietary source of antioxidants (20). Argan oil—a product from the fruit of the argan tree produced and consumed largely in southwestern Morocco—is known for its cosmetic, pharmaceutical, and nutritional virtues. It has been demonstrated that compounds such as tocopherols, sterols, and polyphenols from argan oil have an antioxidative effect (17, 25), while saponins from argan cake press have antiinflammatory properties (26), suggesting a possible role in inhibiting carcinogenesis. To our knowledge, no study of the effects of argan-derived saponins or tocopherols on prostate cancer has been reported yet.

In the present study, we investigated the antiproliferative effect of tocopherols obtained from virgin argan oil and saponins extracted from argan press cake compared with 2ME2 as an antiproliferative drug candidate. We have studied the compounds’ viability and proliferation in two hormone-independent (DU145 and PC3) and one hormone-dependent (LNCaP) human prostate cell lines. Our results indicate that tocopherols and saponins display cytotoxic activity and exert an inhibitory effect on the proliferation of the three prostatic cell lines. The effect is not the same for the three cell lines; LNCaP was clearly the most sensitive of the three. These results are significant because tocopherols’ role as a candidate molecule for the prevention of prostate cancer have been well documented (27, 28).

Venkateswaran et al. (28) demonstrated that physiological concentrations of vitamin E induced cell cycle arrest mediated by up-regulation of the P27 cell cycle regulatory protein. This observation provides a theoretical basis for the putative chemopreventive effect of vitamin E. Also, such clinical trials as the SELECT study (29, 30), the second large-scale study of chemoprevention for prostate cancer which included more than 32,000 men, has suggested that both selenium and vitamin E have potential efficiency in prostate cancer prevention. Considering ? -tocopherols in comparison with all vegetable oils, argan oil seems to be a unique ? -tocopherols-rich oil. Thus, it would be possible that ? -tocopherols extracted from argan oil could have more benefit in chemopreventive action against cancer of the prostate. Taken together, our data are promising for the future use of argan oil in patients developing prostate cancer. The use of ? -tocopherols should be considered for study in future prevention trials.

Only a few studies have showed an antiproliferative effect of saponins on human prostate cancer, notably from ginseng (31, 32). As reported in the literature, 7 major saponins have been identified in argan press cake, which is rare in vegetable oils (33). Saponins isolated from argan press cake are specific and chemically different from those extracted from ginseng and soy. In our study, the saponins isolated from the press cake exhibited cytotoxic activity and inhibited proliferation of LNCaP, DU145, and PC3 cell lines. Our observations that saponins’ antiproliferative effect is dose dependant and that PC3 was the most sensitive cell line are similar to those of Kim et al. (31) and Liu et al. (32), who reported the antiproliferative activity of ginseng saponins in the LNCaP and PC3 cell lines. They suggested that ginseng saponins activate the expression of P21 and P27 as cyclin kinase inhibitors. Also, these saponins blocked LNCaP cells at G1 phase and subsequently inhibited cell growth. Since the chemical structure of argan saponins is different from that of other saponins, it is expected that argan saponins may act with a different mechanism. Thus, the argan saponins could offer a new opportunities for cancer prevention. We believe it would be of use to investigate all argan saponins separately in order to elucidate the role of each in prostate cancer prevention.

Before drawing final conclusions on the mechanisms of the anticancer effects of tocopherols and saponins derived from the argan tree, further investigations concerning the cell proliferation and apoptosis would be necessary and of interest.

Our study suggests for the first time that argan tree compounds could play a role in developing new strategies for the prevention and treatment of prostate cancer. Argan oil and argan press cake constitute additional products that reduce prostate cancer risk factors and delay the onset of prostate carcinogenesis.
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Antiproliferative effect of polyphenols and sterols of virgin argan oil on human prostate cancer cell lines

H. Bennani PhDa, A. Drissi PhDa, F. Giton MScb, L. Kheuang MScb, J. Fiet MD PhDb, A. Adlouni PhDa,*

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In the present study, we evaluated the effect of polyphenols and sterols obtained from virgin argan oil in order to investigate the possible prevention of prostate cancer by studying proliferation in two hormone-independent (DU145 and PC3) and in one hormone-dependent (LNCaP) human prostate cell lines. Our data indicate that the polyphenols of argan oil exerted an inhibitory effect on the proliferation of DU145, LNCaP and PC3 cell lines (GI50 = 75, 100, 50 mg/ml, respectively). The PC3 was more sensitive than the two other cell lines. These results are in agreement with several in vitro studies [24,39–42]. According to Hiipakka et al. (2002) [39], the tea polyphenols could influence some biochemical processes such as inhibition of an enzyme strongly expressed in prostate cancer, ornithin decarboxylase. Also Soya polyphenols could inhibit the autophosphorylation of EGF receptor (epithelial growth factor) which has a tyrosine-kinase activity, normally activated by the EGF [40]. These possible mechanisms show the interest to elucidate the exact mode of action of argan polyphenols and to evaluate their effectiveness in the treatment of prostate cancer in man. Taken together, our findings are promising for the future use of argan oil in patients developing prostate cancer.

Moreover, our results showed that sterols of argan oil produced a time and concentration-dependent decrease in the number of viable cells in all three tested cell lines. DU145 was the most sensitive with only ffi30% viable cells after 24 h treatment with 25 mg/ml. Several studies have demonstrated a significant inverse association between the dietary intake of phytosterols and the risk of prostate cancer [43–45]. Indeed, Von Holtz et al. (1998) observed on prostate cancer cell lines, treated by the phytosterols a reduction of 24% of the growth and a multiplication by four the rate of apoptosis, compared to the same cells treated by the cholesterol. In addition, it has been proposed that the b-sitosterol is effective in the treatment of benign prostatic hypertrophy [46–48]. The major sterols identified in argan oil were schottenol and spinasterol. These sterols are very rare in vegetable oils. There are few studies reporting the anticarcinogenic effect of schottenol and spinasterol. So, it will be interesting to investigate separately these argan sterols in order to clarify the role of each one in cancer prostate prevention.

Before drawing final conclusions about the mechanisms of the anticancer effects of polyphenols and sterols extracted from argan oil, further investigations concerning the cell proliferation and apoptosis would be necessary. Our study suggests for the first time that argan oil compounds could play a role in developing new strategies for the prevention and treatment of prostate cancer. Various studies showed that tocopherols, phytosterols, and polyphenols exert beneficial effects. Knowing the interesting chemical composition of argan oil rich in unsaturated fatty acids and minor compounds, we can consider the possible synergistic effects of these compounds that would be more beneficial than the use of each one.
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