Arctium minus crude extract presents antinociceptive effect in a mice acute gout attack model
2
010; Cronstein and Esserman 2013; Martinon et al. 2006).
January (2015), and a dried voucher specimen is preserved
in the herbarium of the Department of Biology at Federal
University of Santa Maria (register number, SMBD
16046). The seeds (50 g) were removed carefully from
flowers and placed to macerate in 70% ethanol for a week,
with a daily shake-up. After filtration, the solvent was
renewed each week during 1 month. The hydroalcoholic
extract was evaporated under reduced pressure to remove
the ethanol; the remaining aqueous was dried (temperature
below 40 °C) to give the extract.
Thus, an acute gout attack induces the development of
swelling, erythema, and temperature elevation of affected
joint, with severe pain perception, which is a significant
experience of patients with acute gouty arthritis and
responsible for the reduction of their quality of life
(
Richette and Bardin 2010; Terkeltaub 2010).
Among the first-line agents for the treatment of acute
attacks of gout are non-steroidal anti-inflammatory drugs
NSAIDs) or colchicine, an alkaloid derived from the
(
autumn crocus (Colchicum autumnale). However, the use
of NSAIDs is associated with gastrointestinal toxicity and
cardiovascular risk (Cronstein and Esserman 2013; Zhang
et al. 2006), while higher dosages of colchicine can cause
blood dyscrasias, neuromuscular toxicity, and gastroin-
testinal adverse effects (Cronstein and Esserman 2013;
Salvo et al. 2011). Allopurinol, a xanthine oxidase inhi-
bitor, is the main agent used to reduce the hyperuricemia,
although it also can cause adverse reactions including
pruritus and rash (Khanna et al. 2012; Stamp et al. 2015).
The search for new analgesic molecules that combine
high efficacy without inducing adverse effects is the main
objective of the research in the field of pain and analgesia
Drugs and reagents
Synthetic MSU crystals were prepared as described pre-
viously (Hoffmeister et al. 2011; Silva et al. 2013). First,
4 g of uric acid (Vetec, Brazil) was dissolved and heated in
800 mL of ultra-distilled H O (Milli-Q) adjusted to pH 8.9
2
with NaOH (9 mL, 0.5 N) at 60 °C, cooled overnight in a
refrigerator, and then filtered and dried. The needle-like
crystals were recovered and suspended in phosphate-buf-
fered solution (PBS, 10.71 mM K HPO , 6.78 mM
2
4
NaH PO , and 120.4 mM NaCl; pH 7.4). Polarized light
2
4
microscopy was used to confirm that the crystals were rod-
shaped and varied in length (12 ± 2 mm). The preparation
was endotoxin-free, as determined by an amebocyte cell
lysate assay (Sigma, St Louis, MO, USA). The crude
(
Cocco et al. 2003). Natural products have been used in the
process of discovery of new drugs with therapeutic rele-
vance, including analgesic molecules (Koehn and Carter
Ò
2
005; Calixto et al. 2000). Arctium minus (Hill) Bernh. is a
plant which belongs to the family Asteraceae, known as
‘burdock’’ or ‘‘lesser burdock’’, and is a species native to
extract of A. minus was diluted into Tween 80 (polysor-
bate 80, 5%) and saline (0.9% NaCl, 95%) for oral
administration (p.o.). Allopurinol was purchased from
Sigma (USA), dissolved in saline and was also adminis-
tered by oral route. Indomethacin was also purchased from
‘
Asia minor that has spread throughout North America and
Asia (Erdemoglu et al. 2009; Robbins 2013). The A. minus
leaves are used against rheumatic pain, fever, and sun-
stroke in Turkish folk medicine. Furthermore, A. minus
displays anti-inflammatory, antinociceptive, and radical-
scavenging activities (Erdemoglu et al. 2009; Fujita et al.
Ò
local suppliers, but diluted in DMSO (10%), Tween 80
(10%), and saline (0.9% NaCl, 80%), and it was also
administered by oral route. In addition, xanthine oxidase
(XO) from bovine milk and pterin was purchased from
Sigma (USA).
1
995). Species from Arctium genus has been used as an
assistant therapy for the treatment of gout, hypertension,
arteriosclerosis, and other inflammatory diseases (Chan
et al. 2011).
Acetonitrile and methanol were of Chromasolv LC–MS
grade and supplied by Sigma-Aldrich (St. Louis, MO,
United States). Acetic acid was obtained from Sigma-
Aldrich (St. Louis, USA).
Since natural products have been biologically evaluated
for their therapeutic potential, we verified the effect of the
oral treatment with preparations from the A. minus seed
crude extract on antinociceptive and anti-edematogenic
effects in a model of acute gout attack induced by intra-
articular injections of MSU.
The standards (?)-catechin, 3-acetyl coumarin, 3,6-di-
hydroxyflavone, 4-hydroxycoumarin, 6-hydroxycoumarin,
apigenin, chlorogenic acid, chrysin, fisetin, galangin, gallic
acid, kaempferol, luteolin, myricetin, p-coumaric acid,
quercetin, quercitrin, trans-resveratrol, rosmarinic acid,
rutin, trans-cinnamic acid, and vanillic acid were obtained
from Sigma-Aldrich (St. Louis, MO, USA). Caffeic and
ferulic acids were obtained from Fluka Analytical (Buchs,
Switzerland). All the standards were of analytical grade
with a minimum of 95% purity and were used as received.
Materials and methods
Plant collection and extraction
-
1
Stock solutions of the phenolic standards (1000 mg L
)
Flowers of A. minus were collected in Maximiliano de
were prepared by dissolution of appropriate amounts of
substances in LC–MS grade methanol.
Almeida (The Rio Grande do Sul State of Brazil) in
123