Profiles of the Headspace Volatile Organic and Essential Oil Compounds from the Tunisian Cardaria draba (L.) Desv. and Its Leaf and Stem Epidermal Micromorphology

In this work, we investigated aroma volatiles emanated by dry roots, stems, leaves, flowers, and fruits of Cardariadraba (L.) Desv. growing wild in Tunisia and its aerial part essential oils (EOs) composition. A total of 37 volatileorganic compounds (96.7%–98.9%) were identified;4 esters, 4 alcohols, 7 hydrocarbons, 12 aldehydes, 5 ketones,1 lactone, 1 organosulfur compound, 2 organonitrogen compounds, and 1 acid. The hydrocarbons form the maingroup, representing 49.5%–84.6% of the total detected volatiles. The main constituent was 2,2,4,6,6-pentamethylheptane(44.5%–76.2%) reaching the highest relative percentages. Forty-two compounds were determined in thetwo fractions of EOs, representing 98.8% and 97.2% of the total oil composition, respectively. The principal componentswere hexadecanoic acid (34.6%), 6-methyl-5-hepten-2-one (18.3%), decanal (15.0%), 6,10,14-trimethyl-2-pentadecanone (13.2%), and n-pentacosane (13%). Micromorphological details of the leaf and stem epidermisusing light microscopy revealed polygonal cells with sinuous walls in the adaxial and abaxial leaf surfaces andnearly rectangular and long ones with linear and thick walls for the stem epidermis. The stomata complexes wereanisocytic in the leaf epidermis and mainly anisocytic and rarely paracytic in the stem epidermis. Non-glandulartrichomes were unbranched and long with an acute apex or short with a convex apex. The glandular ones wereidentified for the first time in this species. They were short-stalked with a large secretory head. The highest stomatalindex (17.02%) was recorded in the abaxial leaf surface. The identification of headspace volatiles and essentialoil compounds can be used to characterize this species, and the various epidermis micromorphologicalfeatures are very useful for biosystematics taxonomic studies within Brassicaceae.

Isolation of bioactive antioxidant compounds from the aerial parts of Allium roseum var.grandiflorum subvar.typicum Regel.

Objective:To assess the antioxidant activity of aerial parts of Allium roseum var.grandiflorum subvar.typicum Regel.(A.roseum var.grandiflorum subvar.typicum Regel.)for the first time,as well as to isolate the main bioactive compounds.Methods:The chloroformic extract of Allium roseum(A.roseum)and their fractions obtained by subjection to a chromatographic study were tested for their antioxidant activities by using 2,2-diphenyl-2-picrylhydrazyl and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)assays.An activity-guided purification was conducted to isolate five compounds in pure form where their structures were identified by means of nuclear magnetic resonance analyses,including 1D and 2D nuclear magnetic resonance experiments.Results:The evaluation of the antioxidant activity of chloroformic extract and their fractions from A.roseum var.grandiflorum subvar.typicum Regel.showed interesting results.The active chloroformic extract afforded five isolated compounds where their structures were identified as β-sitosterol(1),chrysoeriol(2),luteolin(3),apigenin(4),andβ-sitosterol 3-O-β-D-glucoside(5).All the compounds were isolated for the first time from the A.roseum var.grandiflorum subvar.typicum Regel.The three flavonoids(2–4)exhibited the highest antioxidant activity with IC_(50) values of 62.28,21.26 and 513.42μg/mL,respectively(2,2-diphenyl-2-picrylhydrazyl assay)and 218.00,73.50 and 877.66μg/mL,respectively[2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)assay].An important value of trolox equivalent antioxidant capacity(2.10 mmol/L)was reported for luteolin(3).Conclusions:These results may suggest that the A.roseum var.grandiflorum subvar.typicum Regel.have great potential as a source of a natural preservative ingredient in beneficial for natural health products.