Hypericum
perforatum
Linn (
St. John’s wort
) is a popular and widespread medicine
in Syria, which is used for a wide range of conditions, including
gastrointestinal diseases, heart disease, skin diseases, and psychological
disorders. This widespread use prompted us to identify the main compounds
of this plant from Syria that are responsible for its medicinal properties,
especially since its components differ between countries according
to the nature of the soil, climate, and altitude. This is, to the
best of our knowledge, the first report in which
St. John’s
wort
, a plant native to Syria, is extracted using different
solvents and its most important compounds are identified. In this
study, the dried above-ground parts, i.e., leaves, stem, petals, and
flowers, were extracted using different solvents (water, ethanol,
methanol, and acetone) and extraction protocols. By increasing the
polarity of the solvent, higher yields were obtained, indicating that
mainly hydrophobic compounds were extracted. Therefore, we conclude
that extraction using the tea method or using a mixture of water and
organic solvents resulted in higher yields compared with pure organic
solvents or continuous boiling with water for long periods. The obtained
extracts were analyzed using high-performance liquid chromatography
equipped with a diode array detector (HPLC–DAD), coupled with
UV–visible spectrophotometry at a full spectrum (200–800
nm). The HPLC spectra of the extracts were almost identical at three
wavelengths (260 nm for phloroglucinols (hyperforin and derivates),
590 nm for naphthodianthrones (hypericins), and 350 nm for other flavonols,
flavones, and caffeoylquinic acids), with differences observed only
in the intensity of the peaks. This indicates that the same compounds
were obtained using different solvents, but in different amounts.
Five standards (chlorogenic acid, quercetin, quercitrin hydrate, hyperoside,
and hypericin) were used, and a comparison with retention times and
ultraviolet (UV) spectra reported in the literature was performed
to identify 10 compounds in these extracts: hyperforin, adhyperforin,
hypericin, rutin, quercetin, quercitrin, quercitrin hydrate, hyperoside,
biapigenin, and chlorogenic acid. Although the European Pharmacopoeia
still describes ultraviolet spectroscopy as a method for determining
the quantity of Hyperici herba, interference from other metabolites
can occur. Combined HPLC–DAD and electrospray ionization–mass
spectrometry (LC-ESI-MS) in the positive mode have therefore also
been used to confirm the presence of these compounds in the extracts
by correlating known masses with the identified masses or through
characteristic fragmentation patterns. Total phenolic contents of
the extracts were determined by the Folin–Ciocalteu assay,
and antioxidant activity was evaluated as free radical scavenging
capacity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic
acid) (ABTS) assays. The resul...