Of neo-clerodane diterpenoid

The stereochemistry at C-12 is also very important. This chiral centre of neo-clerodane diterpenoids, C-12 was assumed to have (S) configuration. This view was maintained after X-ray analysis and, chemical correlations with the compounds of known absolute stereochemistry. Hence, Teucrium diterpenoids were invariably found with C-12S configuration. However, recent studies, using H NOE difference techniques [24,25], have shown that S configuration at C-12 is by no means a common stereochemical property. During the investigation... 

E-isolinaridial and E-isolinaridial methylketone are two neo-clerodane diterpenoids isolated from the aerial parts of Linaria saxatilis var. glutinosa (Schrophulariaceae). Benrezzouk et al. evaluated these compounds on multiple inflammation pathways and found that they were not COX-1/COX-2 inhibitors [139]. However, E-isolinaridial and E-isolinaridial methylketone were dual inhibitors against purified phospholipase A2 and 5-lipoxygenase. E-isolinaridial and E-isolinaridial methylketone showed potent inhibition of cell-free 5-LOX enzyme with IC50 values of 0.42 pM and 1.41 pM,... 

Jakupovic et al. [34] investigated some representatives of the genus Baccharis which grow in Texas and Mexico, and seven new e /-clerodane diterpenoids have been described from Baccharis pteronioides D. C. Novel neo-clerodane diterpenoids were also isolated from the aerial parts of B. genistelloides, which were collected in the area of Sao Paulo and neighbouring states of Brazil [35-37] and from Baccharis scoparia (L.) Sw., a species widespread in the Caribbean Islands [38],... 

In case of the presence of an acetyl group at C-3 together with 4, 18-oxirane ring in a neo-clerodane diterpenoid, the H NMR spectrum clearly... 

According to Rowe s nomenclature [14], the hydrogen at C-lOa being and methyl at C-5 P(Me-19) indicate clerodane, the reverse en/-clerodane structure. Roger [ 15] assigned en/-/jeo-clerodane for the former and neo-clerodane for the latter type of stmctures. In the present day, clerodane and neo-clerodane names are used commonly. Most of the diterpenoids isolated from Teucrium species have neo-clerodane structures. 

In Teucrium diterpenoids C-6 position is also very important. Almost all of the neo-clerodane diterpenes have an oxygen function at that location, either as a hydroxyl, acetyl or a ketone, and sometimes as an ether function. In somecases, C-6 hydroxyl group forms a lactone with C-18 methylene group as in compounds 7, 14, 16. The hydroxyl or the acetyl groups could possess a or P stereochemistry. When the literature is studied, there are some discrepancies for the chemical shifts of the C-6 proton, either a or 3, it appears in the lowfield or highfield, as observed in compounds 77 and 78. 

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