Analysis of phenolic compounds in Cynara scolymus L. and Silybum marianum (L.) Gaertn. by HPLC-DAD-ESI/MS
Conference Paper
Overview
Overview
abstract
Cynara scolymus L. (artichoke) and Silybum marianum (L.) Gaertn. (milk thistle)
are medicinal plants native to the Mediterranean Basin that belong to the Asteraceae
family. The flowers and leaves of milk thistle are used in the treatment of liver, spleen
and gallbladder disorders [1] and artichoke leaves are used for their cholagogue,
choleretic and choliokinetic actions, and also for treatment of dyspepsia and as antidiabetics
[2]. The beneficial properties of medicinal plants can be related to their large
diversity of phytochemicals, among which phenolic compounds are outstanding.
Thereby, the aim of the present work was to obtain and compare the phenolic profiles
of artichoke and milk thistle aqueous (prepared by infusion) and hydromethanolic
(maceration in methanol: water 80:20, v/v) extracts, using HPLC-DAD-ESI/MS.
The aqueous extract of artichoke presented higher concentration in total
phenolic compounds (15.29 mg/g extract) than the hydromethanolic extract (4.37
mg/g) with slight differences between the respective profiles; the major flavonoid found
in the aqueous and hydromethanolic extract was luteolin-7-O-glucuronide (5.64 and
0.70 mg/g, respectively), followed by luteolin-7-O-glucoside (2.88 and 0.49 mg/g,
respectively). Monocaffeoylquinic acid derivatives were only present in the
hydromethanolic extract, being 5-O-caffeoylquinic acid (0.49 mg/g) the most abundant
one, while dicaffeoylquinic acid derivatives were mostly identified in the aqueous
extract; 1,3-O-dicaffeoylquinic acid was the most abundant one in both extracts (0.90
and 0.37 mg/g in the aqueous and hydromethanolic extract, respectively). Regarding
to milk thistle preparations, similar phenolic profiles were observed, with only quantitative differences between them. The aqueous extract revealed a higher
phenolic compounds concentration (5.57 mg/g) than the hydromethanolic extract (3.56
mg/g), with apigenin-7-O-glucuronide as the major compound in both preparations
(3.14 mg/g in the aqueous extract, and 0.58 mg/g in the hydromethanolic extract).
Total flavonoids were higher in the aqueous extract (4.66 mg/g), with apigenin-7-Oglucuronide,
luteolin-7-O-glucuronide (1.17 mg/g), and apigenin-O-deoxyhexosylglucuronide
(0.36 mg/g) as the main constituents. The phenolic acids found in the
hydromethanolic extract (total content 1.65 mg/g), included 5-O-caffeolyquinic and
protocatechuic acids (0.56 and 0.44 mg/g, respectively). Besides these phenolic acids,
the hydromethanolic extract also revealed high levels of luteolin-7-O-glucuronide (0.58
mg/g).
Overall, aqueous extracts presented higher phenolic contents than their
hydromethanolic extracts in both species, which could be related with the heat
treatment to which infusions were subjected.
