No abstract

Three compounds were isolated from Acnistus arborescens, a tree commonly used in South and Central America in traditional medicine against several infectious diseases, some of which are caused by fungi. Bioassay-guided fractionation of a MeOH extract of leaves, based on its anti-Pneumocystis carinii activity, led to the isolation of compounds 1-3. Mono- and bidimensional NMR analyses enabled identification of two new withanolides, (20R,22R)-5beta,6beta-epoxy-4beta,12beta,20-trihydroxy-1-oxowith-2-en-24-enolide (1) and (20R,22R)-16beta-acetoxy-3beta,4beta;5beta,6beta-diepoxy-12beta,20-dihydroxy-1-oxowith-24-enolide (2), and withanolide D (3). Antifungal activity on 13 fungi responsible for human infections (five dermatophytes, one nondermatophyte mold, six yeasts, and Pneumocystis carinii) was examined. Cytotoxicity of these compounds was also evaluated in vitro.

Three methoxylated flavones isolated from Marrubium peregrinum - ladanein, scutellarein-5,7,4'-trimethyl ether, and scutellarein-5,6,7,4'-tetramethyl ether - were assayed for their cytotoxicity towards a recently developed dasatinib-resistant murine leukemia cell line (DA1-3b/M2 (BCR-ABL)), together with the structurally related non-methylated flavone scutellarein. The most active compound, ladanein, was looked for in 20 common Lamiaceae species by a quick HPLC screening. Among the possible positive results, the most interesting source was found to be Marrubium vulgare, which led to the isolation and identification of ladanein for the first time in this species. Ladanein also displayed moderate (20-40 microM) activities against K562, K562R (imatinib-resistant), and 697 human leukemia cell lines but was toxic neither to MOLM13 nor to human peripheral blood mononuclear cells. This work provides a common natural source for the hemi-synthesis of future ladanein-derived flavones and the study of their antileukemic activity.