Chemical profiling of botanical supplements: Maca (Lepidium meyenii) and damiana (Turnera diffusa)

The heritage of the knowledge about medicinal plants and their usage is an invaluable treasure for human beings. Over the past decades, the medical and economic benefits of plant-based products have regained recognition, and the usage of botanical supplements has grown rapidly. At the same time, the widespread use of herbal products has raised great concerns about their quality, safety and efficacy. There is an urgent necessity to call for more scientific investigations in this field. In this dissertation, two botanicals, damiana (Turnera diffusa Willd. ex Schult.) and maca (Lepidium meyenii Walpers), were studied. Both have long been used as dietary supplements with claims of tonic and aphrodisiac properties.;A new N-hydroxypyridine derivative (macaridine), a new fatty acid, as well as seven new alkamides were isolated from maca. These compounds could be used as markers for authentication and standardization of maca products. An HPLC analytical method was developed to allow the determination of the marker compounds in maca dietary supplements. The accuracy, precision, linearity, limit of detection and intra/inter day repeatability were determined for the validation. The analysis of several commercial maca products showed significant differences in the quantitative composition.;Six new flavonoids, along with additional 29 compounds were identified from damiana (T. diffusa). Twenty three of these compounds were for the first time reported from this species. Their biological activities, including antimicrobial, antiprotozoal, antileishmanial, anticancer, antioxidant and cytotoxicity activities, were examined. An HPLC method was developed for the authentication and analysis of damiana raw materials and the products, and the HPLC fingerprints of nine samples of Turnera species were obtained. A tritiated water release assay was established to allow measuring the effect of the extract and compounds isolated from T. diffusa on aromatase activity. The isolated flavonoids and the extract of T. diffusa showed potential aromatase inhibitory activity.;Key Words: botanicals, maca, Lepidium meyenii, damiana, Tumera diffusa, aphrodisiac, chemical profiling, structure identification, isolation, HPLC analysis, biological activity, dietary supplements, aromatase, bioassay, flavonoid, alkamide, marker...