The High Content of <i>Ent-</i>11α-hydroxy-15-oxo-kaur- 16-en-19-oic Acid in <i>Adenostemma lavenia</i> (L.) O. Kuntze Leaf Extract: With Preliminary in Vivo Assays

Background: <i>Ent-</i>11&alpha;-hydroxy-15-oxo-kaur-16-en-19-oic acid (11&alpha;OH-KA) is a multifunctional biochemical found in some ferns, <i>Pteris semipinnata</i>, and its congeneric species. Although a number of therapeutic applications of 11&alpha;OH-KA have been proposed (e.g., anti-cancer, anti-inflammation, and skin whitening), the content of 11&alpha;OH-KA in these ferns is not high. <i>Adenostemma lavenia</i> (L.) O. Kuntze, an Asteraceae, has also been reported to contain 11&alpha;OH-KA. The decoction (hot water extract) of whole plants of <i>A. lavenia</i> is used as a folk remedy for inflammatory disorders, such as hepatitis and pneumonia, suggesting that 11&alpha;OH-KA may be the ingredient responsible for the medicinal properties of this plant. Methods: The anti-melanogenic activities of the water extracts of <i>A. lavenia</i> leaves and <i>Pteris dispar</i> Kunze (a cognate of <i>P. semipinnata</i>) leaves were compared in mouse B16F10 melanoma cells. The amount of 11&alpha;OH-KA was measured by using liquid chromatography spectrometry. C57BL/6J mice were treated with the water extract of <i>A. lavenia</i> leaf, and the blood concentration of 11&alpha;OH-KA was measured. The in vivo efficacy of the water extract of <i>A. lavenia</i> leaf was evaluated according to tis anti-melanogenic activity by monitoring hair color. Results: Although both the extracts (<i>A. lavenia</i> and <i>P. dispar</i> Kunze) showed high anti-melanogenic activities, only <i>A. lavenia</i> contained a high amount of 11&alpha;OH-KA, approximately 2.5% of the dry leaf weight. 11&alpha;OH-KA can be purified from <i>A. lavenia</i> leaves in two steps: water extraction followed by chloroform distribution. The treatment of mice with the water extract of <i>A. lavenia</i> leaf suppresses pigmentation in their hairs. Conclusions: Despite the small number of mice examined, the present preliminary result of the suppressed hair pigmentation suggests that the water extract of <i>A. lavenia</i> leaf and the ingredient that is possibly responsible for this&mdash;11&alpha;OH-KA&mdash;are new materials for oral cosmetics. The results may also be helpful in the future development of functional foods and methods to treat patients suffering from hyperpigmentation disorders, such as melasma.