Summary• The hypothesis was tested that flavonoids may scavenge singlet oxygen ( 1 O 2 ) in mesophyll cells of Phillyrea latifolia exposed to excess-light stress.• In cross-sections taken from leaves developed at 10% (shade) or 100% (sun) solar irradiance, we evaluated the excess photosynthetically active radiation (PAR)-induced accumulation of 1 O 2 in mesophyll cells by imaging the fluorescence quenching of theThe intracellular location of flavonoids was also analyzed using three-dimensional deconvolution microscopy.• Photo-induced quenching of DanePy fluorescence was markedly greater in the mesophyll of shade leaves than in that of sun leaves, the former showing a negligible accumulation of mesophyll flavonoids. The photo-induced generation of 1 O 2 was inversely related to the content of flavonoids in the mesophyll cells of sun leaves. Flavonoids were located in the chloroplasts, and were likely associated with the chloroplast envelope.• Here we provide relevant evidence for the potential scavenger activity of chloroplast-located flavonoids against 1 O 2 and new insights into the photo-protective role of flavonoids in higher plants.

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The 1,2-diamine motif is present in a number of natural products with interesting biological activity and in many important pharmaceutical agents. Chiral 1,2-diamines are also widely used as the control elements in asymmetric synthesis and catalysis. Such compounds are thus an attractive target for the synthetic chemist. Although the diamination of an alkene seems an obvious route to these structures, far less research has been devoted to it than to the analogous dihydroxylation or aminohydroxylation reactions that are well-established processes in asymmetric synthesis. Here, we examine recent advances in metal-catalysed diamination reactions and their asymmetric variants. Given the prevalence of these structures, it seems likely that they will find extensive application in the construction of natural products and drug molecules in the near future.

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Total synthesis of naturally occurring casuarine (1) and the first total synthesis of casuarine 6-O-alpha-glucoside (2) were achieved through complete stereoselective nitrone cycloaddition, Tamao-Fleming oxidation and selective alpha-glucosylation as key steps. Biological assays of the two compounds proved their strong and selective inhibitory properties towards glucoamylase NtMGAM and trehalase Tre37A, respectively, which place them among the most powerful inhibitors of these enzymes. The structural determination of the complexes of NtMGAM with 1 and of Tre37A with 2 revealed interesting similarities in the catalytic sites of these two enzymes which belong to different families and clans.