A stereoselective approach to optically active butenolides by Horner–Wadsworth–Emmons olefination reaction of α-hydroxy ketones

Iodine-Mediated Oxidative Rearrangement of α,β-Unsaturated Diaryl Ketones: A Facile Access to 1,2-Diaryl Diketones

A metal-free oxidative rearrangement was explored for the synthesis of 1,2-diaryl diketones by utilizing α,β-unsaturated diaryl ketones and I2/TBHP in good to high yields. The reaction proceeds via oxidative aryl migration, followed by C-C bond cleavage. A simple and high-yielding protocol was developed for the synthesis of a wide range of 1,2-diaryl diketones, which are the backbone for a variety of medicinally important molecules.

Isolation of naturally occurring novel isoflavonoids: an update

This review covers the literature concerning the isolation and identification of new naturally occurring isoflavonoids from Leguminosae and non-Leguminous species between 2012–2017.

Synthesis of tricyclic butenolides and comparison their effects with known smoke-butenolide, KAR1

Plant-derived smoke - butenolide, called at present karrikin 1 (KAR₁) is known as an important inductor of seed germination and seedling growth. In this study, tricyclic butenolides were synthesized and their effects on germination of dormant and non-dormant Avena fatua caryopses were compared, as were also their effects versus those of KAR₁ on seedling growth. KAR₁ was found to be most effective and to completely remove dormancy. Butenolides, rac-8 and (S)-8a, showed a low stimulatory effect on germination of dormant caryopses, visible only when applied at very high concentrations. These compounds used at concentrations 100 times those of KAR₁ similarly increased the speed of germination and vigor of non-dormant caryopses. Likewise, growth of coleoptiles and their fresh weight were increased by KAR₁ as well as by rac-8 and (S)-8a to a similar value. KAR₁ and rac-8 were more effective than (S)-8a in increasing root growth. The results shown indicate that the presence of an aromatic ring in the absence of methyl group at C3 induced a much lower, or a similar, effect on germination of dormant and non-dormant Avena fatua caryopses and seedling growth compared to KAR₁, but only when used at much higher concentrations. The simultaneous presence of a methyl group at C3 and an aromatic ring in the compound rac-7 exerted only a slight effect on the root growth.

Fungal ABC transporter-associated activity of isoflavonoids from the root extract of Dalea formosa

New potential treatments for disseminated fungal infections are needed, especially for infections caused by the commonly drug-resistant pathogens Candida albicans and C. glabrata. These pathogens cause systemic candidiasis, a significant cause of mortality in immune-compromised patients. ABC transporters of the pleiotropic drug resistance subfamily, such as Cdr1p of C. albicans, play an important role in antifungal resistance and are potential bioassay targets for antifungal therapies against drug-resistant pathogens. We observed strong antifungal growth inhibitory activity in the methanol extract of Dalea formosa roots. This extract afforded six new isoflavonoids, sedonans A-F (1-6), a new but-2-enolide, 4'-O-methylpuerol A (7), and the new pterocarpan ent-sandwicensin (8). The structures and absolute configurations of these compounds were assigned using spectroscopic and chiroptical techniques. The direct antifungal activity of 1 against C. glabrata (MIC = 20 μM) was higher than that of fluconazole. Sedonans A-F and ent-sandwicensin were also active against Saccharomyces cerevisiae strains that express differing ABC transporter-associated resistance mechanisms but differed in their susceptibility to Cdr1p-mediated detoxification. A sedonan A (1)/ent-sandwicensin (8) combination exhibited synergistic growth inhibition. The results demonstrate that multiple crude extract compounds are differentially affected by efflux-mediated resistance and are collectively responsible for the observed bioactivity.