Intestinal transport and absorption of bioactive phenolic compounds from a chemically characterized aqueous extract of Athrixia phylicoides

Sandra L Bowles; Yonela Ntamo; Christiaan J Malherbe; Abidemi M P Kappo; Johan Louw; Christo J F Muller

doi:10.1016/j.jep.2017.02.019

Intestinal transport and absorption of bioactive phenolic compounds from a chemically characterized aqueous extract of Athrixia phylicoides

J Ethnopharmacol. 2017 Mar 22:200:45-50. doi: 10.1016/j.jep.2017.02.019. Epub 2017 Feb 16.

Authors

Sandra L Bowles¹, Yonela Ntamo², Christiaan J Malherbe³, Abidemi M P Kappo⁴, Johan Louw⁵, Christo J F Muller⁶

Affiliations

¹ 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.
² 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.
³ 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.
⁴ Department of Biochemistry and Microbiology, University of Zululand, Kwa-Dlangezwa 3886, South Africa. Electronic address: KappoA@unizulu.ac.za.
⁵ 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.
⁶ 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.

PMID: 28213108
DOI: 10.1016/j.jep.2017.02.019

Abstract

Ethnopharmacological relevance: 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.

Aim of the study: 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.

Materials and 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 P_app values 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.

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).

MeSH terms

Asteraceae*
Caco-2 Cells
Dose-Response Relationship, Drug
Humans
Hydroxybenzoates / chemistry*
Hydroxybenzoates / isolation & purification
Hydroxybenzoates / pharmacology
Intestinal Absorption / drug effects*
Intestinal Absorption / physiology
Phenols / chemistry*
Phenols / isolation & purification
Phenols / pharmacology
Plant Extracts / chemistry*
Plant Extracts / isolation & purification
Plant Extracts / pharmacology
Plant Leaves
Plant Stems

Substances

Hydroxybenzoates
Phenols
Plant Extracts
phenolic acid