Five glycosylated flavonoids from the antibacterial butanolic extract of Pituranthos scoparius

Abstract

We have recently reported the antibacterial activity of the essential oils of the stems and the seeds of the endemic species Pituranthos scoparius (Coss. & Dur) Schinz (=Deverra scoparia Coss.& Dur), commonly known as "guezzah" [1]. It is a Saharian species [2] used in traditional medicine for the treatment of asthma and rheumatism [3,4] and in food as a flavoring [3]. Two isocoumarins have been reported from the roots of Pituranthos scoparius [5]. To our knowledge, the aerial parts of this plant have not been the subject of any study. We report here, for the first time, the identification and the antibacterial activity of the flavonoids of the aerial parts of Pituranthos scoparius.Pituranthos scoparius, an endemic species of the Pituranthos genus (Apiaceae), was collected from Ghardaia in April 2003. The plant material was authenticated by Prof. Gerard De Belair (University of Annaba, Algeria) and a voucher specimen (ZKNAPs04/01) was deposited at the Herbarium of the Faculty of Sciences, University Mentouri-Constantine and at the Musee Botanique de la ville d'Angers, France (MBAng2005.13).Air-dried and powdered aerial parts (1 kg) of Pituranthos scoparius were macerated in a methanolic solution (70%), the residue was filtered, concentrated, then successively extracted with petroleum ether, dichloromethane, ethyl acetate and n-butanol. The butanolic extract was concentrated under reduced pressure and column chromatographed on polyamid SC6 with a gradient of toluene-MeOH with increasing polarity. Fraction F 3 was chromatographed on silica gel preparative TLC plates eluted with the system ethylacetate-formic acid-H 2 O (8:1:1), affording compounds 1-3. Fractions F 5 and F 7 were subjected to preparative TLC on polyamid DC6 using H 2 O-MeOH-methylethyl ketone-acetylacetone (13:3:3:1) and flash column chromatography purification with Sephadex LH-20 eluted with methanol, leading to two compounds 4, 5.Acid Hydrolysis. The pure compounds were treated with 2 M HCl at 100°C for 1 h. The hydrolysates were extracted with EtOAc and the aglycones were identified by their UV spectra in methanol and by comparison of their R f with authentic samples.Sugars were identified in the aqueous residue by comparison with authentic samples on silica gel TLC impregnated with 0.2 M NaH 2 PO 4 , solvent Me 2 CO-H 2 O (9:1) revealed with aniline malonate.Compound 1, C 21 H 20 O 10 , mp 227-228°C identified as apigenin 7-O-glucoside or apigetrin [6]. Compound 2, C 21 H 20 O 9 , mp 284°C identified as apigenin 7-O-rhamnoside [6, 7]. Compound 3, C 28 H 32 O 16 , mp 171-173°C. UV (λ max , nm), MeOH: 356, 300sh, 254; +NaOH: 412, 329, 275; + AlCl 3 : 396sh, 361, 300, 267; +HCl: 402, 359, 302sh, 267; +NaOAc: 382, 320, 273; +H 3 BO 3 : 359, 305sh, 270sh, 259.FAB + -MS (m/z): 624 [M+H] + . 1 H NMR (250 MHz, CD 3 OD, δ, ppm, J/Hz): 7.92 (1H, d, J = 2.0, H-2′), 7.68 (1H, dd, J = 8.5, J = 2.0, H-6′), 6.92 (1H,d, J = 8.5, H-5′), 6.40 (1H, d, J = 2.0, H-8), 6.25 (1H, d, J = 2.0, H-6), 5.25 (1H, d, J = 7.5, H-1″glucose), 4.50 (1H, d, J = 1.2, H-1′″rhamnose...

Flavonoids, cytotoxic, antioxidant and antibacterial activities of Evax pygmaea

“…2011 ), isorhamnetin 3- O -β- d -xyloside ( 2 ) (Agrawal and Bansal 1989 ), isorhamnetin 3- O -β- d -glucoside ( 3 ) (Benmekhbi et al. 2008 ), quercetin 3- O -β- d -glucoside ( 4 ) (Touafek et al. 2011 ), quercetin 7- O -β- d -glucoside ( 5 ) (Sikorska & Matławska 2000 ), patuletin 3- O -β- d -glucoside ( 6 ) (Nacer et al.…”

Chemical Variability of the Essential Oil of Pituranthos scoparius from Algeria

“…scoparius contains a large variety of compounds. Five glycosylated flavonoids were isolated in butanolic extract (apigenin 7‐ O ‐glucoside or apigetrin, apigenin 7‐ O ‐rhamnoside, apigenin 6,8‐di‐ C ‐glucoside, isorhamnetin 3‐ O ‐glucoside and apigenin 6,8‐di‐ C ‐glucoside (vicenin‐2)) . Two isocoumarins have been isolated from the ethyl acetate extract of the root of P. scoparius : 6‐hydroxy‐5‐methoxy‐3‐propylisocoumarin and 6‐hydroxy‐5,7‐dimethoxy‐3‐propylisocoumarin .…”

“…Five glycosylated flavonoids were isolated in butanolic extract (apigenin 7-O-glucoside or apigetrin, apigenin 7-Orhamnoside, apigenin 6,8-di-C-glucoside, isorhamnetin 3-O-glucoside and apigenin 6,8-di-C-glucoside (vicenin-2)). [9] Two isocoumarins have been isolated from the ethyl acetate extract of the root of P. scoparius: 6-hydroxy-5-methoxy-3-propylisocoumarin and 6hydroxy-5,7-dimethoxy-3-propylisocoumarin. [10] Two cinnamic acids (5-O-caffeoylquinic acid and 5-feruloylquinic acid), and 13 known flavonoids (vicenin-2, six quercetin and six isorhamnetin O-glycosylated derivatives) were identified in methanolic and aqueous extracts.…”

“…[11] Some biological activities have been reported for the extract or essential oils of P. scoparius, such as antioxidant activity [12 -15] and antimicrobial activity. [9][14] [16] [17] Several studies have been carried out on the composition of P. scoparius essential oil obtained by hydrodistillation of aerial parts, stems, flowers and seeds. However, most of the articles reported on the analysis of only one or two oil samples.…”

Chemical Composition of the Essential Oil of Pituranthos scoparius

“…Only a very few studies were conducted on this plant. The main previous studies deal with the antibacterial of the flavonoids [4] antibacterial activities of the essential oils [1,5], chemical composition of the essential oil of stems and seeds (Table 1) [6,7]. Two isocoumarins from the roots of P. scoparius were isolated [8].…”