Variability in polyphenol content, biological and anthelmintic activity of methanol:water extracts from the leaves of Gymnopodium floribundum Rolfe

Abstract

The effect of the harvest month and age of the leaves of Gymnopodium floribundum on the content of polyphenolic compounds (total phenols (TP), total tannins (TT) and condensed tannins (CT)) of methanol:water extracts was determined. In addition, the biological activity of polyphenols measured as the ability to precipitate protein (PP), inhibit egg hatching (EH), and larval exsheathment (LEI) of Haemonchus contortus was determined. G. floribundum leaves were harvested in 4 mo of the year: December, March, June and September. Twenty-four methanol:water extracts (70:30) were obtained, 12 produced from leaves of varied age (VA) and 12 from 90-d-old leaves (A90). All extracts caused similar PP regardless of age and harvest month. EH inhibition was only significant for December VA extract (EC50 = 374.4 μg/mL; P<0.05). A90 leaf extracts showed a EC50 > 1,500 μg/mL in December, June and September. Although all extracts inhibited larval exsheathment (LEI), the lowest EC50 was that of the VA leaf extract of June (EC50 = 80.4 μg/mL; P<0.05). Incubation of extracts with polyvinylpolypyrrolidone (PVPP) limited LEI (P<0.05), but polyphenols only explained part of that activity. In conclusion, the CT content of G. floribundum leaf extracts depends on their age and harvest month. Polyphenols showed PP activity and were partially associated with LEI. However, polyphenols do not explain the activity against H. contortus eggs.