Antimicobacterial and antioxidant activitiy of Helichrysum devium Johns. from Madeira Archipelago

Plants of the genus Helichrysum belongs to the Asteraceae family. In Madeira Archipelago (Portugal) Helichrysum devium Johns. and Helichrysum melaleucum Rchb. ex Holl, endemic sub-species of Helichrysum, are used in traditional folk medicine for treating bronchitis and pharyngitis. Preliminary biological tests such as evaluation of Artemia salina mortality and antimycobacterial activity were performed with the crude methanol extract of the aerial parts (flowers and leaves) for those two Helichrysum species. The extracts showed high activity on Mycobacterium tuberculosis (<50µg/mL).

Subsequently, aerial parts of H. devium were extracted with solvents of increasing polarity (hexane, chloroform, ethyl acetate and methanol). In the determination of antimycobacterial activity it was observed that the hexane and chloroform extracts have an significant activity. The same extracts were very toxic (˜ 100% of mortality) in the Artemia salina test. All extracts showed remarkable radical scavenging activity in the DPPH assay. For the present studies, H. devium flowers and leaves were evaluated separately, the extracts being obtained by the same method. The antioxidant activities of the leaves and flowers extracts were evaluated using two methods: α- α-Diphenyl-β-picrylhydrazyl (DPPH) and 2,2'azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) assays.[2, 3]

The results are in good agreement and show that the hexane extract of flowers exhibits the highest antioxidant activity, followed by the ethyl acetate, chloroform and methanol extracts, respectively. The ethyl acetate extract of the leaves exhibits the highest antioxidant activity, followed by the chloroform, hexane and methanol extracts.

Acknowledgements: This work was supported in parts by the PhD grant of FCT SFRH/BD/24227/2005.