J Ethnopharmacol. 2016 Oct 20. pii: S0378-8741(16)31424-6. doi: 10.1016/j.jep.2016.10.054. [Epub ahead of print]
- 1Centre
for Indigenous Peoples' Nutrition and Environment, School of Dietetics
and Human Nutrition, McGill University, Macdonald Campus,
Sainte-Anne-de-Bellevue, QC, H9X 3V9, Canada.
- 2Department of Biology, University of Ottawa, Ottawa, ON, K1N 6C5, Canada.
- 3Advanced Molecular Studies-Instituto de Ecología, A.C., Xalapa, Veracruz, México.
- 4Natural
Health Products and Metabolic Diseases Laboratory, Department of
Pharmacology and Montreal Diabetes Research Center, Université de
Montréal, P.O. Box 6128, Downtown Postal Station, Montreal, QC, H3C 3J7,
Canada.
- 5Jardin botanique de Montréal, Institut de recherche en biologie végétale, Université de Montréal, Montréal, QC, H1X 2B2, Canada.
- 6Centre
for Indigenous Peoples' Nutrition and Environment, School of Dietetics
and Human Nutrition, McGill University, Macdonald Campus,
Sainte-Anne-de-Bellevue, QC, H9X 3V9, Canada; Department of Biology,
University of Ottawa, Ottawa, ON, K1N 6C5, Canada. Electronic address:
charris@uottawa.ca.
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE:
Larix laricina, a native tree of North America, is a highly respected medicinal plant used for generations by Indigenous Peoples across its range, including the Cree of northern Québec who use the bark to treat symptoms of diabetes. This study investigates the antioxidant capacity and bioavailability of active constituents identified in L. laricina bark extracts.
MATERIALS AND METHODS:
(1) Oxygen radical absorbance capacity (ORAC) assay was employed to test antioxidant capacity of organic extracts (80% ethanol) from bark of L.laricina as well as fractions, isolated compounds, and media samples collected during permeability assays. (2) Caco-2 cell monolayer cultures were used to determine the permeability
of identified antioxidants, which were quantified in basolateral media
samples using liquid chromatography - tandem mass spectrometry
(HPLC-ESI-MS/MS).
RESULTS:
Crude ethanolic extract possessed strong antioxidant potential in vitro (7.1 ± 0.3 Trolox equivalents (TE) μM /mg). Among the 16L. laricina fractions obtained by chromatographic separation, fraction 10 (F10) showed the highest antioxidant
capacity (21.8 ± 1.7μM TE/mg). Among other identified antioxidants, the
stilbene rhaponticin (isolated from F10) was the most potent (24.6 ±
1.1μM TE/mg). Caco-2
transport studies revealed that none of the identified compounds were
detectable in basolateral samples after 2-hour treatment with crude
extract. In monolayers
treated with F10 (60% rhaponticin), small quantities of rhaponticin
were increasingly detected over time in basolateral samples with
apparent permeability coefficients (Papp) of 1.86 × 10-8cm/sec (0-60min). To model potential effects on blood redox status, we evaluated the antioxidant
capacity of collected basolateral samples and observed enhanced
activity over time after exposure to both extract and F10 (75μg/mL)
relative to control.
CONCLUSIONS:
By profiling the antioxidant constituents of L. laricina bark, we identified rhaponticin as the most potent oxygen radical scavenger and observed low permeability Caco-2 cell monolayers but an increase in basolateral antioxidant capacity.
Copyright © 2016. Published by Elsevier Ireland Ltd.
KEYWORDS:
Tamarack; anti-diabetes; bioavailability; radical; rhaponticin; scavenging
