Abstract: |
Abstract: Utilizing bioassay- and TLC-guided column chromatography, fifteen secondary metabolites
from Populus alba and eight compounds from Salix subserrata were isolated, including a
novel plant metabolite salicyl ether and characterized using ultralviolet light (UV) absorbance,
mass spectrometry (MS), 1H-, 13C-NMR (nuclear magnetic resonance), heteronuclear single
quantum coherence spectroscopy (HSQC) and heteronuclear multiple bond correlation (HMBC).
The extracts, their sub-fractions and the isolated compounds exhibited promising antioxidant
activities in vitro in DPPH and FRAP assays. Also, the extracts of P. alba leaf (PL), shoots (PS),
and S. subserrata leaf (SL) demonstrated substantial antioxidant activities in vivo in the multicellular
model organism Caenorhabditis elegans. For the first time, the isolated secondary metabolites,
aromadendrin, tremuloidin, salicin, isorhamnetin-3-O--d-rutinoside, gallocatechin, triandrin,
and chrysoeriol-7-O-glucuronide were investigated. They exhibited substantial antioxidant activities
in vivo. Salicin, isorhamnetin-3-O--d-rutinoside and gallocatechin, in particular, protected the worms
against a lethal dose of the pro-oxidant juglone (80 M), decreased the endogenous reactive oxygen
species (ROS) level to 45.34%, 47.31%, 68.09% and reduced juglone- induced hsp-16.2::GFP (green
fluorescence protein) expression to 79.62%, 70.17%, 26.77%, respectively. However, only gallocatechin
induced higher levels of sod-3 expression. These findings support the traditional use of Populus alba
and Salix subserrata for treating inflammation especially when ROS are involved.
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