Antiprotozoal and antioxidant alkaloids from Alternanthera littoralis. (February 2017)

• Record Type: Journal Article
• Authors: Koolen, Hector H.F.; Pral, Elizabeth M.F.; Alfieri, Silvia C.; Marinho, Jane V.N.; Serain, Alessandra F.; Hernández-Tasco, Alvaro J.; Andreazza, Nathalia L.; Salvador, Marcos J.
• Is Part Of: Phytochemistry. Volume 134(2017)
• Page Start: 106
• Page End: 113
• Publication Date: 2017-02
• Subjects: Alternanthera littoralis -- Amaranthaceae -- Alkaloids -- Antiprotozoal activities -- Antioxidant activity -- Catechol; Botanical chemistry -- Periodicals; Biochemistry -- Periodicals; Botany -- Periodicals; Chimie végétale -- Périodiques; 572.2
• DOI: 10.1016/j.phytochem.2016.11.008
• Languages: English
• ISSNs: 0031-9422

Abstract

Abstract: Five alkaloids, in addition to hydroxytyrosol and uridine, were isolated from aerial parts of Alternanthera littoralis P. Beauv. Among the isolated compounds, alternamide A was an unusual tricyclic alkaloid with a bridged benzoazepine core. All isolated alkaloids have a catechol moiety, indicating a possible common biosynthetic route. Their structures were established by 1D and 2D NMR spectroscopy in combination with extensive tandem MS experiments by collisional induced dissociation (CID). The antiprotozoal activity of the isolated compounds was assayed against trypomastigote forms of Trypanosoma cruzi and amastigotes of Leishmania amazonensis. Alternamine A was the most active compound, reducing markedly the viability of both parasites. Antioxidant capacities evaluated by ORACFL assay showed that the isolated alkaloids (mainly alternamide B) contributed to the high activity recorded for the ethanolic crude extract; possibly, the catechol moiety present in all structures plays a central role in this result. Graphical abstract: Alternamides A and B, alternamines A and B, along with N -(3, 4-dihydroxyphenethyl)formamide, tyrosol and uridine were isolated from aerial parts of Alternanthera littoralis . Alternamide A and alternamines A and B exhibited antiprotozoal activities with IC50 values in the range of 0.23–0.82 μM. All isolated compounds displayed high antioxidant activity. Highlights: Alkaloids were identified in Alternanthera for the first time. Isolated compounds displayed a common catechol moiety. Isolated alkaloids displayed antiprotozoal and antioxidant activities.