The results showed that the extract and isolated compounds exhibited significant antioxidant activities. Hence this plant has the potential to be a natural antioxidant in the food industry and an anticancer drug.

No abstract

Origanum species are significant aromatic and medicinal plants used in food and pharmaceutical industries. Isolation of bioactive compounds was executed on n-butanol extract to yield the compounds responsible for the activities. Tricosan-1-ol (1), (8E,16E)-tetracosa-8,16-diene-1,24-diol (2), azepan-2-one (3), 3,4-dihydroxybenzoic acid (4), apigenin (5), eriodictyol (6), globoidnan-A (7), luteolin (8), rosmarinic acid (9), apigenin-7-O-glucuronide (10), and vicenin-2 (11) were isolated by chromatographic methods (column chromatography and semi-preparative High Performance Liquid Chromatography (HPLC) and structures were elucidated on the basis of spectroscopic techniques including 1D/2D nuclear magnetic resonance (NMR) and Liquid chromatography/Time-of-flight/Mass spectrometry (LC-TOF/MS). The isolated compounds and extracts were applied for antioxidant assays including 1,1-diphenyl-2-picrylhydrazyl (DPPH • ) scavenging, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS •+ ) scavenging, reducing power, and cuprac techniques. 3,4-Dihydroxy benzoic acid (4), eriodictyol (6), luteolin (8), and rosmarinic acid (9) revealed the considerable antioxidant activities. ARTICLE HISTORY

Sideritis libanotica ssp. linearis was screened for the isolation of new natural antioxidant compounds. The antioxidant activity of flavones obtained from the methanol extract of the plant was evaluated in vitro using total antioxidant, reduction power and free radical scavenging activity. Results were compared with the positive controls of antioxidant standards (α-tocopherol and butylated hydroxytoluene). The results indicate that the flavones possess a higher antioxidant activity when compared to the other components in the plant. The lowest antioxidant activity was observed in fatty acids (FAs) and hydrocarbons. The FAs were methylated with MeOH and KOH and analysed by GC-MS. The structures of the isolated compounds were established based on spectroscopic evidence (NMR, GC-MS, HPLC, IR and UV). In this work, the isolated pure flavone (3'-O-methylhypolaetin 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)]-6″-O-acetyl-β-D-glucopyranoside) was found to possess the highest antioxidant activity.

Five novel 3-alkyl-4-phenylacetylamino-4,5-dihydro-1H-1,2,4-triazol-5-ones (2) were synthesized by the reactions of 3-alkyl-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (1) with phenylacetyl chloride and characterized by elemental analyses and IR, 1 H-NMR, 13 C-NMR and UV spectral data. The newly synthesized compounds 2 were titrated potentiometrically with tetrabutylammonium hydroxide in four non-aqueous solvents such as isopropyl alcohol, tert-butyl alcohol, acetonitrile and N,N-dimethylformamide, and the half-neutralization potential values and the corresponding pK a values were determined for all cases. In addition, these new compounds and five recently reported 3-alkyl-4-(pmethoxybenzoylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (3) were screened for their antioxidant activities.