Foliar exudates of Blakiella bartsiifolia (S.F. Blake) Cuatrec. (Asteraceae, Astereae). A Preliminary study of the Chemical Composition

This is the first phytochemical study of Blakiella bartsiifolia, an endemic species of Mérida. From the foliar exudates two flavonoids ((5,4′-dihydroxy-3,6,7,3′-tetramethoxyflavone; 5,7,4′-trihydroxy-3,8,3′-trimethoxy-flavone) and a labdane diterpene (labda-7,14-dien-13(S)-ol) were identified by high field NMR spectroscopy. Plants naturally exposed to direct sunlight possessed a significantly higher specific absorbance coefficient in the UV region than plants growing in shaded areas.