ANTIOXIDANT ACTIVITY OF TISSUE CULTURE-RAISED BALLOTA NIGRA L. PLANTS GROWN EX VITRO.

Antioxidant properties and total phenolic and flavonoid contents were evaluated in methanolic extracts of shoots from Ballota nigra plants initiated in vitro (from nodal explants) and in vivo (from seeds). The plants were grown in greenhouse and in the field, and were analyzed at the vegetative and flowering stages. The shoot extract of wild-grown plants of B. nigra was also investigated. The results indicate that antioxidant potential of the B. nigra extracts seems to be due to their scavenging of free radicals (DPPH assay) and metal reducing (FRAP test), while they were less effective at the prevention of linoleic acid peroxidation (LPO test). The extracts from shoots of in vitro derived plants were found to exhibit the greatest antioxidant properties. The extracts were also characterized by the highest content of phenolic compounds and their level was affected by plant developmental stage. The extracts of shoots collected at the flowering period exhibited higher amounts of phenolics and flavonoids than in the extracts of immature plants. A close correlation between the total phenolic content and flavonoid content and antioxidant activity using the DPPH and FRAP assays was obtained. The results of the present study suggest the use in vitro-derived plants of B. nigra instead of using wild plants for pharmaceutical purposes.