Abstract
The aqueous methanolic extract of Teucrium oliverianum was partitioned with different solvent systems with increasing polarities. The phytochemical investigation of the CHCl3 fraction led to the isolation of six compounds. The structures of the compounds were determined by NMR co-chromatographic TLC and found to be: 8-O-acetylharpagide 1, 12-O-methylteucrolin A 2, teucrolivin A 3, eupatorin 4, teucrolivin B 5 and 24 (S)-stigmasta-5, 22, 25-trip-3 beta-ol 6. The total extract and the isolated compounds were tested for their ability to induce the cytoprotective enzyme NAD (P)H:quinone oxidoreductase (NQO1). Among the purified compounds, the diterpenoid, teucrolivin B 5 was the only one which was able to induce NQO1 by more than 2-fold, whereas the flavonoid eupatorin 4 was the most potent inducer, increasing the NQO1 specific activity by 1.75-fold at a concentration of 25 mu g/ml. Compounds 2, 3 and 6 were essentially inactive, indicating that compounds 1, 4 and 5 are the main contributors to the NQO1 inducer activity of the total extract.