Leaves from California yerba santa (Eriodictyon californicum) have been used historically by indigenous peoples for medicinal purposes. Recent research has ascribed potential pharmaceutical effects to leaf polyphenols, without a consideration of other constituents. Based on prior analyses of polyphenols in leaves sampled in nature, five accessions known to be rich in sterubin and five accessions known to be rich in eriolic acid C were grown from seeds in Ontario, Oregon, and samples of their leaves were harvested and evaluated for their essential oil and polyphenol contents. The major essential oil components in E. californicum were 1,8-cineole (0.6–35.5%), (Z)-β-ocimene (6.8–15.7%), terpinen-4-ol (8.3–16.1%), α-pinene (2.6–13.6%), β-phellandrene (1.9–11.7%), γ-terpinene (4.6–7.9%), ethyl (E)-cinnamate (0.2–8.9%), α-terpineol (1.5–5.2%), p-cymene (2.0–5.3%), and β-pinene (0.6–6.8%). Fifteen polyphenols with a prominence of eriolic acid C, rosmarinic acid, sterubin, homoeriodictyol, 6-methoxynaringenin, hesperetin, and eriodictyol were identified. Essential oils may contribute to the medicinal properties of the leaves of California yerba santa. Results from the ten samples were evaluated for both polyphenols and essential oils; the variations in several essential oils may be correlated to variations in some of the polyphenols.
Shock et al. (Tue,) studied this question.