Antioxidant capacity of origanum heracleoticum l. flower and leaf extracts and their essential oil profiles of plants from micropropagation and collection from natural habitats
Maria Geneva, Ely Zayova, Marieta Hristozkova , Ira Stancheva
The composition of the essential oils and the antioxidant properties
of Origanum heracleoticum L. leaves and flowers collected from four
different natural populations in Bulgaria (two locations in Kresna
Gorge and two locations in Rhodopes Mountain) were studied and
compared with those of micropropagated and field-adapted plants.
Explants for micropropagation from wild-growing plants from Gorna
Breznitsa (Kresna Gorge) were used. The enzyme antioxidant potential
characterised by the activity of superoxide dismutase, catalase,
guaiacol peroxidase, ascorbate peroxidase as well as the non-enzyme
antioxidant potential characterized by the content of phenols,
flavonoids, water- and lipid-soluble antioxidant metabolites, were
affected by environmental conditions and type of propagation (wild
or micro). The highest enzyme antioxidant potential was observed in
the flowers and leaves of the micropropagated plants, followed by the
plants collected from Gorna Breznitsa. The variation in the content of
metabolites with antioxidant potential in the Greek oregano collected
from the two locations from each two areas of Bulgaria was detected.
The higher content of phenols and flavonoids was detected in
micropropagated plants as well as in wild-plants collected from two
localities from Kresna Gorge, when compared with the wild-plants
collected from Eastern Rhodopes. Forty-five compounds in the O.
heracleoticum essential oil collected from the native populations
were identified. Based on the essential oil composition, and especially
on the carvacrol and thymol contents, the O. heracleoticum plants
from all investigated natural populations in Bulgaria belonged to the
carvacrol chemotype. Besides environmental conditions, another
factor that affected the composition of O. heracleoticum essential oil
was the existence of chemotypes.