Naphtho[2,3-c]furan-4,9-diones and related compounds: theoretically interesting and bioactive natural and synthetic products

Sc(OTf)3-Mediated One-Pot Synthesis of Coumarin-Fused Furans: A Thiol-Dependent Reaction for the Easy Access of 2-Phenyl-4H-furo[3,2-c]chromen-4-ones

Herein, we report a simple and efficient method for the preparation of novel thioether-linked coumarin-fused furans from the one-pot three-component reaction of arylglyoxal, 4-hydroxycoumarin, and various aromatic thiols in the presence of Sc(OTf)₃ as a catalyst. This methodology is also applicable to cyclic 1,3-dicarbonyls such as cyclohexane-1,3-dione and dimedone. Depending upon the thiols, this methodology can either give a three-component thioether-linked coumarin-fused furan (4) or a two-component furocoumarin product (5). Wide substrate scope, good to excellent yields, and products having more than one pharmaceutically important motif are the salient features of this methodology.

Epoxyquinophomopsins A and B from endophytic fungus Phomopsis sp. and their activity against tyrosine kinase

Two new quinone derivatives, epoxyquinophomopsins A (1) and B (2), were purified from the EtOAc extract of endophytic fungus Phomopsis sp isolated from Morus cathayana. The structures of both compounds were determined based on 1D and 2D NMR and mass spectral data, as well as by x-ray diffraction analysis for 1. Compounds 1 and 2 were screened against eight receptor- (RTKs) and eight non-receptor tyrosine kinases (nRTKs). Both compounds showed strong inhibitory properties against Bruton's Tyrosine Kinase (nRTK) with their kinase activity were 19% and 20%, respectively. Only compound 1 that showed strong inhibitory properties against RTKs EGFR and HER-4 with its kinase activity were 16 and 15%, respectively. Thus, both compounds have potential as tyrosine kinase inhibitors.

Ethnobotany, phytochemistry and pharmacological significance of the genus Bulbine (Asphodelaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Bulbine (Asphodelaceae) is spread across Southern Africa and Australia and has been traditionally used for various medicinal applications such as treating skin diseases, burns, diarrhoea, and sexually transmitted diseases.

AIM OF THIS REVIEW

The aim is to present a critical review of the ethnomedicinally important species of the genus Bulbine with a comprehensive overview of their chemical constituents and biological activities.

MATERIALS AND METHODS

This paper is an overview of literature published on the genus Bulbine in the last six decades with regards to phytochemical composition and their respective pharmacological potentials with the aid of data obtained from the search engine Google Scholar with string searches performed using keywords to obtain relevant publications from scientific databases including ACS Journals, PubMed, Science Direct, SciELO, Sci Finder, Springer, Tailor & Francis, The Plant List Database, Web of Science and Wiley.

RESULTS

The literature survey reveals that only 12 species in the genus Bulbine have been reported to be used traditionally with scientific records of ethnomedicinal usage Anthraquinones appeared as the most abundant phytochemicals in the genus. Other isolated/detected metabolites include isofuranonaphthoquinones, flavonoids, and triterpenoids. Promising pharmacological activities have been reported by members of the genus with antiplasmodial, antitrypanosomal, antiviral, antioxidant, anticancer, anti-inflammatory and anti-microbial activity, potent wound healing properties as well as improved reproduction.

CONCLUSIONS

This review showed the traditional uses of this genus and its preventative and curative properties in the management of the listed diseases providing support from bioassays of the tested compounds and extracts. State-of-the-art analytical techniques are required for the characterisation and quantification of the compounds within the genus. The efficacy of the therapeutic potential of the Bulbine species need to be further confirmed with pre-clinical and clinical studies.

Biscogniauxone, a New Isopyrrolonaphthoquinone Compound from the Fungus Biscogniauxia mediterranea Isolated from Deep-Sea Sediments

The properties and the production of new metabolites from the fungal strain LF657 isolated from the Herodotes Deep (2800 m depth) in the Mediterranean Sea are reported in this study. The new isolate was identified as Biscogniauxia mediterranea based on ITS1-5.8S-ITS2 and 28S rRNA gene sequences. A new isopyrrolonaphthoquinone with inhibitory activity against glycogen synthase kinase (GSK-3β) was isolated from this fungus. This is the first report of this class of compounds from a fungus isolated from a deep-sea sediment, as well as from a Biscogniauxia species.

The deep eutectic melt of sorbitol and metformin hydrochloride: synthesis of 3-substituted 2-aminonaphtho[2,3-b]furan-4,9-diones and their photophysical properties

The low-melting deep-eutectic mixture of sorbitol and metformin HCl was successfully employed as a recyclable solvent for promoting the synthesis of benzofuroquinone dyes.

Total synthesis of monosporascone and dihydromonosporascone

The first synthesis of monosporascone has been achieved in five steps and 57% overall yield.

Et3N-induced demethylation-annulation of 3-alkynyl-4-methoxy-2-pyridones and structurally related compounds in the synthesis of furan-fused heterocycles

Various 3-iodo-4-methoxypyridin-2-ones and related pyrone and coumarin derivatives have been demonstrated as readily available precursors of 2-substituted furan-fused heterocycles by means of in situ sequential Sonogashira-acetylide coupling, dealkylation, and regioselective furan annulation reactions. A Et3N-induced S(N)2 process has been established that accounts for the dealkylation process.

New cytotoxic furoquinones obtained from terpenyl-1,4-naphthoquinones and 1,4-anthracenediones

A series of new furoterpenyl-1,4-naphtho(anthra)quinones have been prepared via oxidative cyclization of the corresponding 2-hydroxy-3-butenyl-1,4-naphtho(anthra)quinones. Depending on the reaction conditions the 1,2-quinones or the 1,4-quinones were obtained. Several new furo-1,4-anthraquinones were also obtained by condensation of 2,3-dichloroquinones with 1,3-dicarbonyls. The compounds synthesized have been evaluated for their cytotoxicity against neoplastic cell lines, some of them being effective below the micromolar level.

A novel manganese(iii) acetate mediated reaction between 2-benzoyl-1,4-naphthoquinones and 1,3-dicarbonyl compounds

A manganese(III)-mediated reaction between 2-benzoyl-1,4-naphthoquinones and 1,3-dicarbonyl compounds is described. This reaction provides an effective method for the synthesis of naphtho[2,3-c]furan-4,9-diones and naphthacene-5,12-diones, and it shows fair to high chemoselectivity depending on the electronic effect of the benzoyl group substituent on the reactants. With ethyl benzoylacetate and 1,3-diketones, the novel naphtho[2,3-c]furan-4,9-diones were produced effectively with high selectivity.