TITLE:
Total Phenolic Compounds, Carotenoids and In Vitro Antioxidant Activity of Three Traditional Indigenous Medicinal Plants of Saskatchewan, Canada
AUTHORS:
Matheus Antonio Filiol Belin, Fidji Gendron, Stephen Cheng, Vincent Ziffle
KEYWORDS:
Aralia nudicaulis L., Rubus idaeus L., Rosa arkansana Porter, DPPH, FRAP, ABTS
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.12 No.8,
August
9,
2021
ABSTRACT: Medicinal plants are an important component in
Indigenous cultures. Aralia nudicaulis L., Rubus idaeus L., and Rosa arkansana Porter were analyzed for total phenolic compounds, carotenoids and antioxidant
activity by DPPH (2,2-diphenyl-1-picrylhydrazyl), FRAP (ferric-reducing
antioxidant power), and ABTS (2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic
acid). The samples were harvested in Saskatchewan, Canada, with the help of an
Indigenous Traditional Knowledge Keeper and the analyses were performed by spectrophotometry.
The results showed that total phenolic compounds amount ranged from 0.08 to
0.88 mg GAE/mg d.w. and the total carotenoid contents ranged from 0.03 to 1.26
mg/g d.w. The in vitro antioxidant
activity ranged from 0.02 to 0.71 μmol TE/mg d.w. by DPPH, from 0.05 to 2.53
μmol TE/mg d.w. by FRAP, and from 0.04 to 1.06 μmol TE/mg d.w. by ABTS. Rosa arkansana leaves stood out
with higher amounts of total phenolic compounds (TPC) (0.88 ± 0.02 mg GAE/g
d.w.), carotenoids (TC) (1.26 ± 0.03 mg/g d.w.) and antioxidant activity (TAA)
by DPPH (0.71 ± 0.01 μmol TE/mg d.w.), ABTS (1.06 ± 0.01 μmol TE/mg d.w.) and
FRAP (2.32 ± 0.01 μmol TE/mg d.w.), with the same amount of Rubus idaeus belowground (2.53 ±
0.01 μmol TE/mg d.w.) in last technique (2.32 ± 0.01 μmol TE/mg d.w.). The
first principal component describes 83.88% of the total variance and all the
variables have high influence on this component (factor loadings: T = 0.976, TC
= 0.735, TAA by DPPH = 0.955, FRAP = 0.894 and ABTS = 0.996), demonstrating that
these samples do not have large dissimilarity. The second principal component
represents 13.64% of the total variance, and the TC is the dominant variable on
the second principal component (0.658). Aralia nudicaulis, Rubus idaeus, and Rosa arkansana had interesting amounts of total phenolic
compounds, total carotenoids and in vitro antioxidant activity. Rosa arkansana leaves and Rubus idaeus have the highest
amount of total phenolic compounds and antioxidant activity in this study. Rosa arkansana leaves are also a
good source of carotenoids, and so, they have great potential health benefits
and use in industry as a source of bioactive compounds with high antioxidant
activity. This study enriches the literature on medicinal plants used by
Indigenous people of Saskatchewan and surrounding Canada. More studies are
necessary to identify its applications, security and to assess which compounds
generate the benefits reported by Traditional Knowledge Keepers.