The selected plants belong to different families, such as Araceae, Liliaceae, Polygonaceae, Brassicaceae, Plantaginaceae,
etc. It is known that different solvents can extract different molecules, depending on their polarities and solubilities, from plants. So the plant materials were separately extracted with hexane, ethanol, and water by maseration and biological activities of these extracts were analyzed and compared with different polarities. The yields of the extracts are given in
Table 2.
Antioxidant activities of the extracts were examined using spectrophotometric assays with the ABTS cation radical scavenging activity and CUPRAC (
37). Most of the extracts showed acceptable antioxidant activities (
Table 3). Among the extracts, the ethanol extract of
R. acetosella (
3) had the highest antioxidant potential for ABTS and CUPRAC with IC
50 value of 23.73 µg/mL and 25.31 µg/mL, respectively. Isbilir and Sagiroglu have reported that
R. acetosella includes rutin, flavone glycosides, vitamins, carotenoids, minerals, and phenolics, so it has various biological acitivites such as antioxidant, anticancer, antidiabet, and anti-inflammatory effects. Additionally, the methanol extract of
R. acetosella showed the highest antioxidant activity with IC
50 value of 0.03 µg/mL in DPPH assay in this report (
40). Also, Alpinar
et al. tested antioxidant capacity of
R. acetosella using CUPRAC method (0.12 ± 0.03 mmol g
-1) and they found similar results with our study (
41). It is known that
Rumex genus is rich in anthracene derivatives. Wegiera
et al. identified that
Rumex species contain chrysophanol, physcion, emodin, aloe-emodin, barbaloin, sennoside A, and sennoside B, as anthracene derivatives oftheir studies showed that the antioxidant potentials of anthrecene derivatives were determined with various methods such as DPPH radical scavenging ability, reducing power, and superoxide scavenging activity (
42).
On the other hand, the ethanol extract of
P. lanceolata (
9) exhibited low to moderate antioxidant activity for ABTS and CUPRAC with IC
50 value of 39.28 µg/mL and 40.65 µg/mL, respectively. Ferrezzano
et al. have reported that methanol : water extract of
P. lanceolata includes phenolic acids, flavonoids, coumarins, lignans, lipids, and cinnamic acids (
43). The antioxidant effect of this species could be related to contained substances and mostly like the results of the synergic activity of the main compounds. The antioxidant effects of
O. sigmodeum (
2),
S. vulgaris (
7),
A. millefolium subsp.
pannonica (
6) and
C. squamatus (
8) species have not been investigated up to now. As seen in
Table 3, the results of antioxidant assays showed that the all extracts were showed moderately antioxidant activity.
The inhibitory activities of the extracts of selected species on AChE and BChE were determined by the Ellman’s method using galantamine as the reference compound (
36). The IC
50 values for AChE and BChE inhibitions are summarized in
Table 3. IC
50 values against AChE are between 7.24 µg/mL and 165.20 µg/mL. IC
50 values against BChE are between 6.40 µg/mL and 142.78 µg/mL.
The anticholinesterase activity (against acetyl- and butryl-cholinesterase enzymes) of extracts was compared with that of galantamine (IC
50 = 0.5 ± 0.01), used as a standard drug against Alzheimer’s disease. Among them, the hexane extract of
Capsella bursa-pastoris (
4) has the highest inhibitory activity against AChE (IC
50 = 7.24 ± 0.08).
C. bursa-pastoris has various biological activities such as antibleeding, anticancer, and
antithrombin,
etc. because of containing minerals, vitamins, ascorbic acid, proteins, linoleic acid, fatty acids (
44). Grosso
et al. investigated the metabolic profile of
C. bursa-pastoris with methanol extract and quercetin-6-C-glucoside, kaempferol-3-O-glucoside, fatty acids, organic acids, aminoacids, and sterols were determined. According to the presented study by Grosso
et al., the methanol extract of
C. bursa-pastoris had moderate inhibitory activity against AChE (19% inhibition at a concentration of 0.1 mg/mL) (
44).
The hexane extract of
A. millefolium subsp
. pannonica (
6) had the highest BChE inhibitory activity with IC
50 value of 6.40 µg/mL, in our study. Karaalp
et al. have previously reported that
Achillea species include flavonoids and sesquiterpen lactones. It is known that flavonoids have anticholinesterase properties and several biological activities (
45). Also, sesquiterpene lactones have various biological activities such as antiinflammatuar, antipyretic, antimalarial, antimicrobial, antiviral, antiphytoviral, antiulserogenic, smooth muscle contractility, immunologic, neurotoxic, and cytotoxic (
46). It can be said that due to synergic interactions between these compounds and
A. millefolium, this species might be an effective cholinesterase inhibitor.
Sixteen percent of the all plant extract samples have minimal or no cholinesterase inhibitory activity. This result showed that most of the active molecules against AChE and BChE were in hexane (nonpolar solvent) extract. This may be most likely due to anticholinesterase activity of nonpolar compounds found in high amounts within these extracts. The studying of nonpolar extracts for anticholinesterase activity are worth further phytochemical evaluation for identifying their active components.
Antiaflatoxigenic activities of the extracts of all selected plants were tested
in-vitro according to R-Biopharm Elisa Fast aflatoxin method (
39). The results of antiaflatoxigenic assay showed that the ethanol extract of
P. lanceolata and
A. millefolium subsp
. pannonica exhibited good potential to reduce the amount of aflatoxin.