Quassinoid

Abstract: The Simaroubaceae form a large botanical family of mostly pantropical distribution; only a few representatives (such as Ailanthus) extend into temperate regions. Many species of this family, for example Quassia amara L. (Surinam quassia) and Picraena excelsa Lindt. (=Picrasma excelsa Planch or Aeschrion excelsa Kuntze, Jamaica quassia, have been known, for over a century, to contain bitter substances which are called collectively “quassin“. However, the isolation of individual constituents and even more, the elucidation of their structures was not accomplished until modern physical techniques of investigation were available. Amongst these, thin layer chromatography, nuclear magnetic resonance spectroscopy, circular dichroism and mass spectroscopy should be mentioned. An example of the power of the new physical techniques in this field, and particularly that of NMR spectroscopy, is provided by the chemistry of quassin (1) and neoquassin (2), the first Simaroubaceae constituents whose structures were established by VALENTA and his co-workers (74, 75) in the early 1960’s. During the intervening years a number of genera of the family Simarubaceae have been investigated and many new bitter constituents have been isolated and had their structures elucidated (see Tables). These Simaroubaceae constituents, which occur either as esters or in the free state, are all closely related chemically and form the bitter principles of the quassin group, which are called quassinoids (13).

Abstract: Bruceantin, purified from an Ethiopian plant used to treat dysentery, killed Entamoeba histolytica in vitro (IC50 [the concentration of drug which decreased the number of colonies to half that of controls] = 0.018 microgram/ml). Six related quassinoids of 17 tested were also amoebicidal. No relationship between quassinoid structure and amoebicidal activity was apparent.

Abstract: New cytostatic quassinoids, 6α-hydroxyeurycomalactone (1), longilactone (2) and 14, 15β-dihydroxyklaineanone (3) were isolated from the woods of Eurycoma longifolia (Simaroubaceae) with three cytotoxic quassinoids, 11-dehydroklaineanone (4), eurycomalactone (5) and 5, 6-dehydroeurycomalactone (6), and with seven cytotoxic tirucallane-type triterpenes, niloticin (7), dihydroniloticin (8), piscidinol A (9), bourjotinolone A (10), 3-episapelin A (11), melianone (12) and hispidone (13). All of them showed potent cytotoxic activity against P388 and KB cells.

Abstract: To investigate natural inhibitors against tobacco mosaic virus (TMV) from plants, 10 known β-carboline alkaloids and one quassinoid have been isolated from MeOH extract of the wood of Picrasma quassioides Benn. These compounds were screened for their inhibitory activities against tobacco mosaic virus (TMV). The activity of each compound against TMV infection and replication was tested using a half-leaf assay method, a leaf-disk method, and Western blotting analyses. All of the β-carboline alkaloids showed moderate anti-TMV activities and exhibited synergistic effects when combined with the quassinoid nigakilactone B (11). To our knowledge, this is the first report on anti-TMV activity of β-carbolines and their synergistic effects against TMV when combined with a quassinoid.