Phenomycin, toxicity and distribution

Bioactivity profile of dissolved organic matter and its relation to molecular composition

Dissolved organic matter (DOM) occupies a huge and uncharted molecular space. Given its properties, DOM can be presented as a promising biotechnological resource. However, research into bioactivities of DOM is still in early stages. In this study, the biotechnological potential of terrestrial and marine DOM, its molecular composition and their relationships are investigated. Samples were screened for their in vitro antibacterial, antifungal, anticancer and antioxidant activities. Antibacterial activity was detected against Staphylococcus aureus in almost all DOM samples, with freshwater DOM showing the lowest IC50 values. Most samples also inhibited Staphylococcus epidermidis, and four DOM extracts showed up to fourfold higher potency than the reference drug. Antifungal activity was limited to only porewater DOM towards human dermatophyte Trichophyton rubrum. No significant in vitro anticancer activity was observed. Low antioxidant potential was exerted. The molecular characterization by FT-ICR MS allowed a broad compositional overview. Three main distinguished groups have been identified by PCoA analyses. Antibacterial activities are related to high aromaticity content and highly-unsaturated molecular formulae (O-poor). Antifungal effect is correlated with highly-unsaturated molecular formulae (O-rich). Antioxidant activity is positively related to the presence of double bonds and polyphenols. This study evidenced for the first time antibacterial and antifungal activity in DOM with potential applications in cosmeceutical, pharmaceutical and aquaculture industry. The lack of cytotoxicity and the almost unlimited presence of this organic material may open new avenues in future marine bioprospecting efforts.

Ni(II)-Catalyzed Enantioselective Synthesis of β-Hydroxy Esters with Carboxylate Assistance

A Ni-oxazoline complex-catalyzed asymmetric decarboxylative aldol reaction between malonic acid half-oxyesters and various carbonyls with carboxylate assistance was developed, affording structurally diverse β-hydroxy esters with good yields and enantioselectivities under mild conditions. Importantly, the broad substrate scope of this methodology enabled rapid accesses to several natural products and their analogues as exemplified by phenylpropanoid, phaitanthrin B, and phthalide.

Weakly-coordinating N-oxide and carbonyl groups for metal-catalyzed C–H activation: the case of A-ring functionalization

This feature review is focused on recent challenges based on the functionalizations at C-8 and C-5 positions of heterocyclic and quinoidal compounds – a topic that is still rarely explored in the literature.

Ruthenium-catalyzed C–H oxygenation of quinones by weak O-coordination for potent trypanocidal agents

C–H oxygenation of quinones by weak O-coordination was achieved by versatile ruthenium(ii) catalysis with ample substrate scope and trypanocidal compounds were also identified.

Direct sequential C–H iodination/organoyl-thiolation for the benzenoid A-ring modification of quinonoid deactivated systems: a new protocol for potent trypanocidal quinones

Under a combination of AgSR with a copper source, sulfur-substituted benzenoid quinones were prepared in high yields (generally >90%). The compounds have presented significant activity against T. cruzi, the etiologic agent of Chagas disease.

Overcoming naphthoquinone deactivation: rhodium-catalyzed C-5 selective C-H iodination as a gateway to functionalized derivatives

We report a Rh-catalyzed method for the C-5 selective C-H iodination of naphthoquinones and show that complementary C-2 selective processes can be achieved under related conditions. C-C bond forming derivatizations of the C-5 iodinated products provide a gateway to previously inaccessible A-ring analogues. The present study encompasses the first catalytic directed ortho-functionalizations of simple (non-bias) naphthoquinones. The strategic considerations outlined here are likely to be applicable to C-H functionalizations of other weakly coordinating and/or redox sensitive substrates.

A Direct Asymmetric Synthesis of Juglomycin A

Juglomycin A has been synthesized in four steps from 5-methoxy-1-naphthol.