Analysis of Antioxidant Prenylflavonoids in Different Parts of Macaranga Tanarius, the Plant Origin of Okinawan Propolis

Objective: To analyze the antioxidant prenylflavonoids in different parts of Macaranga tanarius (M. tanarius) (Euphorbiaceae) including the leaf, petiole, stem, leaflet, flower and fruit (only in female plant), and to evaluate their antioxidant properties.

Methods: Methanol extracts of each part of M. tanarius were prepared and five prenylflavonoids in them were quantitatively analyzed using HPLC. The fruits from female plant were further separated into seed, pericarp, and glandular trichome. After the quantitative analyses of prenylflavonoids in each part of M. tanarius, antioxidant activity of the extracts was evaluated by 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging assay.

Results: The leaf of M. tanarius contained two prenylflavonoids as main components in both male and female plants. Both flowers (male and female) contained five kinds of prenylflavonoids. In the petiole, stem and leaflet of both male and female plants, the prenylflavonoids were not detected or their amounts were very low. Five kinds of prenylflavonoids were detected in the seed, pericarp and glandular trichome of female M. tanarius. In particular, the glandular trichome had the highest level of total prenylflavonoids (235 mg/g of fresh plant). DPPH radical scavenging activity of all parts was more than 30%.

Conclusions: We found that different parts of M. tanarius contained antioxidant prenylflavonoids. In particular, not only the glandular trichome but also the leaf contained prenylflavonoids, which indicated that M. tanarius may be developed as a functional plant, because the leaves of this plant can be easily collected.