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Milk thistle and prostate cancer: differential effects of pure flavonolignans from Silybum marianum on antiproliferative end points in human prostate carcinoma cells.
Cancer Res. 2005 May 15; 65(10):4448-57.CR

Abstract

Extracts from the seeds of milk thistle, Silybum marianum, are known commonly as silibinin and silymarin and possess anticancer actions on human prostate carcinoma in vitro and in vivo. Seven distinct flavonolignan compounds and a flavonoid have been isolated from commercial silymarin extracts. Most notably, two pairs of diastereomers, silybin A and silybin B and isosilybin A and isosilybin B, are among these compounds. In contrast, silibinin is composed only of a 1:1 mixture of silybin A and silybin B. With these isomers now isolated in quantities sufficient for biological studies, each pure compound was assessed for antiproliferative activities against LNCaP, DU145, and PC3 human prostate carcinoma cell lines. Isosilybin B was the most consistently potent suppressor of cell growth relative to either the other pure constituents or the commercial extracts. Isosilybin A and isosilybin B were also the most effective suppressors of prostate-specific antigen secretion by androgen-dependent LNCaP cells. Silymarin and silibinin were shown for the first time to suppress the activity of the DNA topoisomerase IIalpha gene promoter in DU145 cells and, among the pure compounds, isosilybin B was again the most effective. These findings are significant in that isosilybin B composes no more than 5% of silymarin and is absent from silibinin. Whereas several other more abundant flavonolignans do ultimately influence the same end points at higher exposure concentrations, these findings are suggestive that extracts enriched for isosilybin B, or isosilybin B alone, might possess improved potency in prostate cancer prevention and treatment.

Authors+Show Affiliations

Natural Products Laboratory, Research Triangle Institute, Research Triangle Park, North Carolina 27709-2194, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

15899838

Citation

Davis-Searles, Paula R., et al. "Milk Thistle and Prostate Cancer: Differential Effects of Pure Flavonolignans From Silybum Marianum On Antiproliferative End Points in Human Prostate Carcinoma Cells." Cancer Research, vol. 65, no. 10, 2005, pp. 4448-57.
Davis-Searles PR, Nakanishi Y, Kim NC, et al. Milk thistle and prostate cancer: differential effects of pure flavonolignans from Silybum marianum on antiproliferative end points in human prostate carcinoma cells. Cancer Res. 2005;65(10):4448-57.
Davis-Searles, P. R., Nakanishi, Y., Kim, N. C., Graf, T. N., Oberlies, N. H., Wani, M. C., Wall, M. E., Agarwal, R., & Kroll, D. J. (2005). Milk thistle and prostate cancer: differential effects of pure flavonolignans from Silybum marianum on antiproliferative end points in human prostate carcinoma cells. Cancer Research, 65(10), 4448-57.
Davis-Searles PR, et al. Milk Thistle and Prostate Cancer: Differential Effects of Pure Flavonolignans From Silybum Marianum On Antiproliferative End Points in Human Prostate Carcinoma Cells. Cancer Res. 2005 May 15;65(10):4448-57. PubMed PMID: 15899838.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Milk thistle and prostate cancer: differential effects of pure flavonolignans from Silybum marianum on antiproliferative end points in human prostate carcinoma cells. AU - Davis-Searles,Paula R, AU - Nakanishi,Yuka, AU - Kim,Nam-Cheol, AU - Graf,Tyler N, AU - Oberlies,Nicholas H, AU - Wani,Mansukh C, AU - Wall,Monroe E, AU - Agarwal,Rajesh, AU - Kroll,David J, PY - 2005/5/19/pubmed PY - 2005/7/8/medline PY - 2005/5/19/entrez SP - 4448 EP - 57 JF - Cancer research JO - Cancer Res. VL - 65 IS - 10 N2 - Extracts from the seeds of milk thistle, Silybum marianum, are known commonly as silibinin and silymarin and possess anticancer actions on human prostate carcinoma in vitro and in vivo. Seven distinct flavonolignan compounds and a flavonoid have been isolated from commercial silymarin extracts. Most notably, two pairs of diastereomers, silybin A and silybin B and isosilybin A and isosilybin B, are among these compounds. In contrast, silibinin is composed only of a 1:1 mixture of silybin A and silybin B. With these isomers now isolated in quantities sufficient for biological studies, each pure compound was assessed for antiproliferative activities against LNCaP, DU145, and PC3 human prostate carcinoma cell lines. Isosilybin B was the most consistently potent suppressor of cell growth relative to either the other pure constituents or the commercial extracts. Isosilybin A and isosilybin B were also the most effective suppressors of prostate-specific antigen secretion by androgen-dependent LNCaP cells. Silymarin and silibinin were shown for the first time to suppress the activity of the DNA topoisomerase IIalpha gene promoter in DU145 cells and, among the pure compounds, isosilybin B was again the most effective. These findings are significant in that isosilybin B composes no more than 5% of silymarin and is absent from silibinin. Whereas several other more abundant flavonolignans do ultimately influence the same end points at higher exposure concentrations, these findings are suggestive that extracts enriched for isosilybin B, or isosilybin B alone, might possess improved potency in prostate cancer prevention and treatment. SN - 0008-5472 UR - https://www.unboundmedicine.com/medline/citation/15899838/Milk_thistle_and_prostate_cancer:_differential_effects_of_pure_flavonolignans_from_Silybum_marianum_on_antiproliferative_end_points_in_human_prostate_carcinoma_cells_ L2 - http://cancerres.aacrjournals.org/cgi/pmidlookup?view=long&pmid=15899838 DB - PRIME DP - Unbound Medicine ER -