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Eriodictyon sessilifolium, an endemic Hydrophyllaceae of Baja California (Mexico), has been studied for the natural products exuded by glandular trichomes covering its leaves and stems. Major components of this exudate were isolated and identified by spectroscopic methods to be 4-hydroxy-3-(2,3-dihydroxy-3-methylbutyl)-benzoic acid methyl ester (1), the natural methyl ester of anodendroic acid (2), and 2,2-dimethyl-3-hydroxychroman-6-carboxylic acid methyl ester (3). Possible biosynthetic relations between these new natural products are considered. In addition, 9 known flavonoid aglycones were identified as exudate constituents.

Seven species of the genus Baccharis have been analyzed for flavonoid aglycones. Many known methylated flavones, flavonols and flavanones were identified. From B. sarothroides, two novel flavonols were isolated and elucidated as 5,7,4′-trihydroxy-3,6,8-trimethoxyflavone and its methyl ether, 5,4′-dihydroxy-3,6,7,8-tetramethoxyflavone. Previous literature reports on flavonoids in Baccharis are summarized and their distribution and external occurrence is discussed. One novel diterpene and one rare triterpene were found in the terpenoid fractions that constitute most of the exudate material in these and other Compositae.

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