Antiprotozoal activities of Melampyrum arvense and its secondary metabolites

• Published in: Planta Medica
• Main Authors: Kırmızıbekmez, H, Atay, İ, Kaiser, M, Yeşilada, E, Tasdemir, D
• Format: Conference Proceeding
• Language: English
• Published: 21.07.2009
• ISSN: 0032-0943; 1439-0221
• DOI: 10.1055/s-0029-1234331

The genus Melampyrum (Scrophulariaceae) consists of annual semi-parasitic plants and represented by two species, M. arvense and M. pratense in the flora of Turkey [1] . In the continuation of our efforts to find natural antiprotozoal compounds from the Scrophulariaceae family [2,3], the crude MeOH extract of M. arvense was found to show in vitro activity against parasitic protozoa Trypanosoma brucei rhodesiense and Leishmania donovani (IC 50 values 8.8 and 30.5µg/ml). The MeOH extract was suspended in H 2 O and partitioned against CHCl 3 . Both aqueous and CHCl 3 phases showed activity against two parasites and possessed no cytotoxicity against mammalian L6 cells (IC 50 >90µg/ml). An activity guided fractionation of the H 2 O extract using MPLC and repeated column chromatography techniques afforded ten pure compounds, whose structures were elucidated by spectroscopic methods ( 1 H and 13 C NMR, ESIMS) to be iridoid glucosides aucubin (1) , melampyroside (2) , mussaenoside (3) , mussaenosidic acid (4) , 8- epi -loganin (5) , flavonoids, apigenin (6) , luteolin (7) , luteolin 7- O -glucopyranoside (8), lignan glycoside dehydrodiconiferyl alcohol 9- O -β-glucopyranoside (9) and benzoic acid (10) . All compounds showed moderate to remarkable trypanocidal activity (IC 50 s 3.8–60.8µg/ml), with compound 7 being the most potent one. The majority of the metabolites also possessed leishmanicidal properties and again compound 7 was the most active constituent (IC 50 3.0µg/ml). Except for compounds 6 and 7 , all compounds lacked cytotoxicity towards mammalian cells (IC 50 >90µg/ml). This is the first detailed phytochemical study on Turkish M. arvense and first report on the antiprotozoal effect of the plant and its constituents. References: 1. Hedge, I.C. (1967) Melampyrum L. in: Flora of Turkey and East Aegean Islands Vol. 6, Ed. Davis P.H., University Press. Edinburgh. 2. Tasdemir, D. et al. (2005) Phytochemistry 66:355–362. 3. Tasdemir, D. et al. (2008) Phytomedicine 15:209–215.