title: Intestinal transport and absorption of bioactive phenolic compounds from a chemically characterized aqueous extract of Athrixia phylicoides.
abstract: BACKGROUND
  Athrixia phylicoides, popularly known as "bush tea", is an indigenous aromatic shrub found in mountainous and grassland areas of the northern and eastern parts of southern Africa. The plant is traditionally used for the treatment of several ailments, including coughing, treating infected wounds, treating boils and sore throat, hypertension and heart disease. Potential anti-diabetic effects have also been demonstrated in vitro.
  
  
  OBJECTIVE
  To investigate the intestinal transport of prominent phenolic constituents, across a fully differentiated Caco-2 monolayer, using a characterized aqueous extract of A. phylicoides, previously shown to have bioactivity.
  
  
  METHODS
  HPLC-DAD and LC/MS analyses were used to identify the major phenolic compounds within the extract. Intestinal transport of the phenolic compounds was assessed using a differentiated Caco-2 monolayer model in order to predict bioavailability and identify metabolite formation. Rate of transport, efflux and percentage cross-over were calculated for the respective phenolic compounds.
  
  
  RESULTS
  Nine prominent compounds, present in the aqueous extract of A. phylicoides, were identified. Of these, three phenolic acids (protocatechuic acid, caffeic acid and para-coumaric acid), crossed the Caco-2 cell monolayer in significant amounts, with Pappvalues of 4.52, 4.35 (×10-6cm/s) and 2.38 (×10-5cm/s), respectively. para-Coumaric acid was shown to have the highest predicted bioavailability.
  
  
  CONCLUSIONS
  Para-Coumaric acid, identified for the first time in A. phylicoides, was shown to have the highest predicted bioavailability suggesting that it could play a major role in the bioactivity of A. phylicoides.
authors.affiliation: Biomedical Research and Innovation Platform, South African Medical Research Council, P.O. Box 19070, Tygerberg 7505, South Africa. Electronic address: Sandra.Bowles@mrc.ac.za.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Bowles
authors.affiliation: Biomedical Research and Innovation Platform, South African Medical Research Council, P.O. Box 19070, Tygerberg 7505, South Africa; Department of Biochemistry and Microbiology, University of Zululand, Kwa-Dlangezwa 3886, South Africa. Electronic address: Yonela.Ntamo@mrc.ac.za.
authors.forename: Yonela
authors.initials: Y
authors.lastname: Ntamo
authors.affiliation: Plant Bioactives Group, Post-Harvest and Wine Technology Division, Agricultural Research Council, Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch 7599, South Africa. Electronic address: MalherbeCh@arc.agric.za.
authors.forename: Christiaan J
authors.initials: CJ
authors.lastname: Malherbe
authors.affiliation: Department of Biochemistry and Microbiology, University of Zululand, Kwa-Dlangezwa 3886, South Africa. Electronic address: KappoA@unizulu.ac.za.
authors.forename: Abidemi M P
authors.initials: AM
authors.lastname: Kappo
authors.affiliation: Biomedical Research and Innovation Platform, South African Medical Research Council, P.O. Box 19070, Tygerberg 7505, South Africa; Department of Biochemistry and Microbiology, University of Zululand, Kwa-Dlangezwa 3886, South Africa. Electronic address: Johan.Louw@mrc.ac.za.
authors.forename: Johan
authors.initials: J
authors.lastname: Louw
authors.affiliation: Biomedical Research and Innovation Platform, South African Medical Research Council, P.O. Box 19070, Tygerberg 7505, South Africa; Department of Biochemistry and Microbiology, University of Zululand, Kwa-Dlangezwa 3886, South Africa; Department of Medical Physiology, Stellenbosch University, Tygerberg 7507, South Africa. Electronic address: Christo.Muller@mrc.ac.za.
authors.forename: Christo J F
authors.initials: CJ
authors.lastname: Muller
mesh_terms: D019659:Asteraceae; D018938:Caco-2 Cells; D004305:Dose-Response Relationship, Drug; D006801:Humans; D062385:Hydroxybenzoates / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D007408:Intestinal Absorption / Q000187:drug effects* / Q000502:physiology; D010636:Phenols / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D018515:Plant Leaves; D018547:Plant Stems
chemical_list: D062385:Hydroxybenzoates; D010636:Phenols; D010936:Plant Extracts; C017616:phenolic acid
keywords: 3,4 di-O-caffeoylquinic acid (PubChem CID: 5281780); 3,5 di-O-caffeoylquinic acid (PubChem CID: 6474310); 4,5 di-O-caffeoylquinic acid (PubChem CID: 6474309); Athrixia phylicoides; Caco-2 transport; Caffeic acid; Para-coumaric acid; Protocatechuic acid; caffeic acid (PubChem CID: 689043); chlorogenic acid (PubChem CID: 1794427); cryptochlorogenic acid (PubChem CID: 9798666); neochlorogenic acid (PubChem CID: 5280633); para-coumaric acid (PubChem CID: 637542); protocatechuic acid (PubChem CID: 72)