7.72 (1H, d, J = 15.9, H-7ꢃꢃꢃ), 7.48 (2H, d, J = 8.6, H-2ꢃꢃꢃ, 6ꢃꢃꢃ), 7.40 (2H, d, J = 15.9, H-7ꢃꢃꢃꢃ), 7.30 (2H, d, J = 8.6, H-2ꢃꢃꢃꢃ, 6ꢃꢃꢃꢃ),
6.86 (2H, d, J = 8.9, H-5ꢃ, 3ꢃ), 6.81 (2H, d, J = 8.6, H-5ꢃꢃꢃ, 3ꢃꢃꢃ), 6.80 (2H, d, J = 8.6, H-5ꢃꢃꢃꢃ, 3ꢃꢃꢃꢃ), 6.45 (1H, d, J = 15.9, H-8ꢃꢃꢃꢃ),
6.25 (1H, d, J = 2.0, H-8), 6.07 (1H, d, J = 15.9, H-8ꢃꢃꢃ), 6.05 (1H, d, J = 2.0, H-6), 5.65 (1H, d, J = 8.2, Glc H-1ꢃꢃ), 4.37 (1H,
dd, J = 11.9, 1.9, H-6ꢃꢃa), 4.22 (1H, dd, J = 11.9, 6.6, H-6ꢃꢃb), 3.40–5.20 (sugar protons). In addition, HPLC-UV-DAD permitted
the characterization of compound 3 as kaempferol 3-O-[2ꢃꢃ,6ꢃꢃ-di-O-E-p-coumaroyl]-ꢄ-D-glucoside [7, 9, 10].
Compound 4. C H O . UV (MeOH, ꢁ , nm): 267, 352; +NaOH: 275, 325, 403; +AlCl : 274, 398; +AlCl /HCl:
27 30 15
max
3
3
1
275, 396; +NaOAc: 274, 376; +H BO : 269, 357. H NMR (250 MHz, CD OD, ꢂ, ppm, J/Hz): 8.09 (2H, d, J = 9.0, H-6ꢃ, 2ꢃ),
3
3
3
6.92 (2H, d, J = 9.0, H-5ꢃ, 3ꢃ), 6.44 (1H, d, J = 2.1, H-8), 6.24 (1H, d, J = 2.1, H-6), 5.16 (1H, d, J = 7.7, Glc H-1ꢃꢃ), 4.50 (1H,
d, J = 1.5, Rha H-1ꢃꢃꢃ), 1.15 (3H, d, J = 6.2, Rha H-6ꢃꢃꢃ), 3.20–4.00 (sugar protons). In addition, HPLC-UV-DAD permitted the
characterization of compound 4 as kaempferol 3-O-[ꢅ-L-rhamnosyl-(6ꢆ1)-O-ꢄ-D-glucoside [11].
Acid hydrolysis of compound 4 produced kaempferol and glucose + rhamnose, confirming the nature of the two
sugars.
Compound 5. C H O . UV (MeOH, ꢁ , nm): 257, 358; +NaOH: 274, 325, 409; +AlCl : 274, 432; +AlCl /HCl:
27 30 16
max
3
3
1
275, 425; +NaOAc: 273, 388; +H BO : 264, 381. H NMR (250 MHz, CD OD, ꢂ, ppm, J/Hz): 7.55 (1H, dd, J = 8.2, 2.1,
3
3
3
H-6ꢃ), 7.53 (1H, d, J = 2.1, H-2ꢃ), 6.83 (1H, d, J = 8.2, H-5ꢃ), 6.36 (1H, d, J = 2.0, H-8), 6.17 (1H, d, J = 2.0, H-6), 5.33 (1H, d,
J = 7.3, Glc H-1ꢃꢃ), 4.38 (1H, sl, Rha H-1ꢃꢃꢃ), 0.99 (3H, d, J = 6.2, Rha CH ), 3.00–3.90 (sugar protons). In addition, HPLC-UV-
3
DAD permitted the characterization of compound 5 as quercetin 3-O-[ꢅ-L-rhamnosyl-(6ꢆ1)-O-ꢄ-D-glucoside] [7, 9].
Acid hydrolysis of compound 5 produced quercetin and glucose + rhamnose, confirming the nature of the two sugars.
Phenols Quantification. Total phenolics was quantified according to the Folin–Ciocalteu method using pyrogallol
as a standard [12].
Antioxidant Activity. The free radical scavenging activity of the n-butanolic extract of Eryngium triquetrum Vahl.
(BEET) was measured by a slightly modified method of Hatano [13, 14]. One milliliter of a 0.2 mM DPPH methanol solution
was added to 4 mL of various concentrations of the extract in methanol. The mixture was shaken vigorously and left to stand
at room temperature. After 30 min, the absorbance of the solution was measured at 517 nm and the antioxidant activity
calculated using the following equation: Scavenging capacity % = 100 – [(Ab of sample – Ab of blank) – 100/Ab of control].
Methanol (1 mL) plus plant extract solution (4 mL) were used as a blank, while DPPH solution plus methanol was used as a
negative control. The positive control was DPPH solution plus 1 mM rutin. Extract concentration providing 50% inhibition
(IC ) was calculated from the plot of inhibition percentage against extract concentration.
50
Antibacterial Activity. Susceptibility of the bacterial strains to the chloroform extract of Eryngium triquetrum Vahl.
(CEET) was investigated using the disk diffusion method and by comparing their antibiogram inhibition zones to those reported
by the National Committee for Clinical Laboratory Standards (NCCLS) [15]. A range of microorganisms, namely Escherichia
coli ATCC 25922, Escherichia coli, Staphylococcus aureus ATCC 43300, Staphylococcus aureus, Pseudomonas aeruginosa
ATCC 27853, Pseudomonas aeruginosa, Klebsiella pneumonia, and Morganella morganii were used. The reference strains
were obtained from the Pasteur Institute (Algiers). The other strains were obtained from the laboratory of bacteriology, Benbadis
Hospital, Constantine, using conventional methods (clinical isolation).
The five flavonol glycosides were reported for the first time from the species E. triquetrum Vahl., and two were
isolated for the first time from the genus, which are kaempferol-3-O-ꢄ-(6ꢃꢃ-O-E-p-coumaroyl)-ꢄ-D-glucopyranoside and
kaempferol-3-O-ꢅ-L-rhamnopyranosyl-(1ꢆ6)-ꢄ-D-glucopyranoside.
A significant phenolic content (>16 g/100 g of dry extract) and good radical scavenging activity were found for the
BEET (IC 136 ꢇg/mL), compared with the reference (quercetin IC 12 ꢇg/mL).
50
50
The CEET inhibited the growth of the tested miroorganisms. The best antibacterial activity was observed against
Staphylococcus aureus, Staphylococcus aureus ATCC 43300, Escherichia coli ATCC 25922, Escherichia coli, and Morganella
morganii with 30, 24, 22, 20, and 20 mm inhibition zone diameters, respectively, with 80 ꢇg/mL MIC value.
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B. Muckensturm, A. Boulanger, M. Farahi, and J. P. Reduron, Nat. Prod. Res., 24, 391 (2010).
M. Adams, W. Althera, M. Kessler, M. Kluge, and M. Hamburger, J. Ethnopharmacol., 133, 278 (2011).
M. Vigneron, E. Deparis, E. Deharo, and G. Bourdy, J. Ethnopharmacol., 98, 351 (2005).
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