Salt effect on phenolics and antioxidant activities of Tunisian and Canadian sweet marjoram (Origanum majorana L.) shoots.
BACKGROUND
Two varieties of Origanum majorana (Canadian and Tunisian) were evaluated for their phenolic, flavonoid and tannin contents, individual phenolic compounds and antioxidant activities under NaCl constraint.


RESULTS
The results showed a significant variability in phenolic composition and antioxidant behavior between the two varieties under salt stress. The phenolic composition of methanolic extracts was determined by reversed-phase high-performance liquid chromatography. Amentoflavone was the predominant flavonoid compound; in addition, trans-2-hydrocinnamic acid became the major phenolic acid with salt treatment of the Tunisian variety. In the control, Canadian variety extract was characterized by high levels of gallic acid and amentoflavone. However, under 75 mmol L(-1) NaCl, gallic acid content doubled, whereas amentoflavone content was maintained in the Canadian variety. Stimulation of phenolic acid biosynthesis was observed in these two varieties under salt treatment despite the fact that shoots of the Tunisian variety showed higher antioxidant activities compared to those from the Canadian variety. Tunisian O. majorana might have developed tolerance to salinity and avoided tissue damage by activating enzymes involved in the galactosylation of quercetin into quercetin-3-galactoside and quercetin-3-rhamnoside.


CONCLUSIONS
Our results confirmed the tolerance of Tunisian O. majorana plants.
Unité de Physiologie et Biochimie de la Tolérance au Sel des Plantes, Département de Biologie, Faculté des Sciences de Tunis, Campus Universitaire, 1060 Tunis, Tunisia; Laboratoire des Substances Bioactives, Centre de Biotechnologie de Borj-Cedria, 2050 Hammam-lif, Tunisia.
Olfa
O
Baâtour
Hela
H
Mahmoudi
Imen
I
Tarchoun
Nawel
N
Nasri
Najla
N
Trabelsi
Rym
R
Kaddour
Maha
M
Zaghdoudi
Ghaith
G
Hamdawi
Riadh
R
Ksouri
Mokhtar
M
Lachaâl
Brahim
B
Marzouk
D000975:Antioxidants / Q000494:pharmacology*; D044946:Biflavonoids / Q000378:metabolism / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000378:metabolism; D002170:Canada; D005419:Flavonoids / Q000378:metabolism* / Q000494:pharmacology; D005707:Gallic Acid / Q000378:metabolism / Q000494:pharmacology; D031341:Origanum / Q000187:drug effects* / Q000378:metabolism; D010636:Phenols / Q000378:metabolism* / Q000494:pharmacology; D010666:Phenylpropionates / Q000378:metabolism / Q000494:pharmacology; D010851:Picrates / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D011794:Quercetin / Q000378:metabolism; D055049:Salt Tolerance; D012492:Salts / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology*; D013045:Species Specificity; D013312:Stress, Physiological; D013634:Tannins / Q000378:metabolism* / Q000494:pharmacology; D014416:Tunisia
D000975:Antioxidants; D044946:Biflavonoids; D001713:Biphenyl Compounds; D005419:Flavonoids; D010636:Phenols; D010666:Phenylpropionates; D010851:Picrates; D012492:Salts; D013634:Tannins; D012965:Sodium Chloride; C035253:3-phenylpropionic acid; D005707:Gallic Acid; C011164:amentoflavone; D011794:Quercetin; C004931:1,1-diphenyl-2-picrylhydrazyl