{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T23:52:05Z","timestamp":1791849125997,"version":"4.3.4"},"reference-count":44,"publisher":"Georg Thieme Verlag KG","funder":[{"name":"National Research Foundation of South Africa","award":["MND210615611632, PMDS240814259024"],"award-info":[{"award-number":["MND210615611632, PMDS240814259024"]}]},{"name":"South African Rooibos Council","id":[{"id":"https:\/\/ror.org\/04vwzyt55","id-type":"ROR","asserted-by":"crossref"}]},{"name":"Department of Science, Technology, and Innovation of South Africa"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Planta Med"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>The presence of plant polyphenols with pharmacophoric features similar to estrogens in an Aspalathus linearis (rooibos) extract warranted the in vitro evaluation of the estrogenic activity of green and fermented rooibos extracts (n = 18). Whole-cell receptor binding assays demonstrated that compounds found within the rooibos extracts interact with both estrogen receptor (ER) subtypes, as they displaced radiolabeled E2. Although the extracts were much less potent than E2 in inducing agonism in promoter-reporter luciferase assays, most extracts displayed ER\u03b2 selectivity with higher efficacy via ER\u03b2 than via ER\u03b1. In contrast, extract potencies were generally comparable to ICI-182,780, an ER antagonist, in antagonizing E2, while their efficacies showed no ER-subtype selectivity. The preference of selected water extracts (WEs) to signal via ER\u03b2 was apparent in their inability to induce progesterone receptor (PGR) mRNA expression, an ER\u03b1-activated gene. Furthermore, the lack of PGR stimulation was consistent with Western blot assay results, where most WEs downregulated PR-B protein expression after shorter treatment times (2 or 4 h) and inhibited E2-induced PR-B protein expression after 24 or 48 h. To our knowledge, this study is the first to report that rooibos possesses antiestrogenic activity. This warrants further research for identifying the active compound(s) underlying the antiestrogenic effect, and for supporting the potential of rooibos as a therapeutic agent in diseases regulated by E2, such as ER-positive breast cancer.<\/jats:p>","DOI":"10.1055\/a-2963-2494","type":"journal-article","created":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T23:15:43Z","timestamp":1791846943000},"source":"Crossref","is-referenced-by-count":0,"title":["Evaluation of the Estrogenic Activity of Green and Fermented Aspalathus linearis (Rooibos) Extracts"],"prefix":"10.1055","author":[{"given":"Sasha M.J.","family":"Marais","sequence":"additional","affiliation":[{"name":"Stellenbosch University, WC, South Africa","place":["Stellenbosch"],"department":["Department of Biochemistry"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6778-2455","authenticated-orcid":false,"given":"Glenn","family":"Averia","sequence":"additional","affiliation":[{"name":"Stellenbosch University, WC, South Africa","place":["Stellenbosch"],"department":["Department of Biochemistry"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lee-Maine L.","family":"Spies","sequence":"additional","affiliation":[{"name":"Stellenbosch University, WC, South Africa","place":["Stellenbosch"],"department":["Department of Biochemistry"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dalene","family":"De Beer","sequence":"additional","affiliation":[{"name":"Agricultural Research Council Infruitec Nietvoorbij, WC, South Africa","place":["Stellenbosch"],"department":["Plant Bioactives Group, Post-Harvest & Agro-Processing Technology"]},{"name":"Stellenbosch University, WC, South Africa","place":["Stellenbosch"],"department":["Department of Food Science"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ann","family":"Louw","sequence":"additional","affiliation":[{"name":"Stellenbosch University, WC, South Africa","place":["Stellenbosch"],"department":["Department of Biochemistry"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3786-6452","authenticated-orcid":false,"given":"Nicolette","family":"Verhoog","sequence":"additional","affiliation":[{"name":"Stellenbosch University, WC, South Africa","place":["Stellenbosch"],"department":["Department of Biochemistry"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"194","published-online":{"date-parts":[[2026,10,12]]},"reference":[{"key":"ref1","doi-asserted-by":"crossref","first-page":"114658","DOI":"10.1016\/j.ejmech.2022.114658","article-title":"An overview on Estrogen receptors signaling and its ligands in breast cancer","volume":"241","author":"M ZI Khan","year":"2022","journal-title":"Eur J Med Chem"},{"key":"ref2","doi-asserted-by":"crossref","first-page":"10681","DOI":"10.1039\/D3FO04702D","article-title":"Estrogen receptor-mediated health benefits of phytochemicals: a review","volume":"14","author":"J Li","year":"2023","journal-title":"Food Funct"},{"key":"ref3","doi-asserted-by":"crossref","first-page":"4970","DOI":"10.1038\/sj.onc.1203828","article-title":"Estrogen receptor \u03b2 acts as a dominant regulator of estrogen signaling","volume":"19","author":"K Pettersson","year":"2000","journal-title":"Oncogene"},{"key":"ref4","doi-asserted-by":"crossref","first-page":"587386","DOI":"10.3389\/fonc.2020.587386","article-title":"Estrogen receptor Beta (ER\u03b2): a ligand activated tumor suppressor","volume":"10","author":"R Mal","year":"2020","journal-title":"Front Oncol"},{"key":"ref5","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1007\/s12672-017-0298-1","article-title":"Estrogen receptor-\u03b2 modulation of the ER\u03b1-p53 loop regulating gene expression, proliferation, and apoptosis in breast cancer","volume":"8","author":"W Lu","year":"2017","journal-title":"Horm Cancer"},{"key":"ref6","first-page":"13","article-title":"Combinatorial treatments of tamoxifen and SM6Met, an extract from Cyclopia subternata Vogel, are superior to either treatment alone in MCF-7 cells","author":"L van Dyk","year":"2022","journal-title":"Front Pharmacol"},{"key":"ref7","first-page":"14","article-title":"Cyclopia extracts act as selective estrogen receptor subtype downregulators in estrogen receptor positive breast cancer cell lines: comparison to standard of care breast cancer endocrine therapies and a selective estrogen receptor agonist and antagonist","author":"F R Olayoku","year":"2023","journal-title":"Front Pharmacol"},{"key":"ref8","doi-asserted-by":"crossref","first-page":"100615","DOI":"10.1016\/j.hermed.2022.100615","article-title":"What has been the focus of rooibos health research? 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