Andirol A and B, two unique 6-hydroxymethylpterocarpenes from Andira inermis

N2-fixing tropical legume evolution: a contributor to enhanced weathering through the Cenozoic?

Fossil and phylogenetic evidence indicates legume-rich modern tropical forests replaced Late Cretaceous palm-dominated tropical forests across four continents during the early Cenozoic (58-42 Ma). Tropical legume trees can transform ecosystems via their ability to fix dinitrogen (N2) and higher leaf N compared with non-legumes (35-65%), but it is unclear how their evolutionary rise contributed to silicate weathering, the long-term sink for atmospheric carbon dioxide (CO2). Here we hypothesize that the increasing abundance of N2-fixing legumes in tropical forests amplified silicate weathering rates by increased input of fixed nitrogen (N) to terrestrial ecosystems via interrelated mechanisms including increasing microbial respiration and soil acidification, and stimulating forest net primary productivity. We suggest the high CO2 early Cenozoic atmosphere further amplified legume weathering. Evolution of legumes with high weathering rates was probably driven by their high demand for phosphorus and micronutrients required for N2-fixation and nodule formation.

NMR spectral assignments of a new [C--O--C] isoflavone dimer from Andira surinamensis

The phytochemical investigation of extracts from the branch wood and branch barks of Andira surinamensis yielded a novel isoflavone dimer, 4'-methoxyisoflavone-(7-O-7'')-3''',4'''-methylenedioxyisoflavone (surinamensin), along with the triterpene lupeol and the known isoflavones 5,7-dihydroxy-4'-methoxyisoflavone (biochanin A), 5,4'-dihydroxy-7-methoxyisoflavone (prunetin), 7,3'-dihydroxy-4'-methoxyisoflavone (calycosin), and 5,7,3'-trihydroxy-4'-methoxyisoflavone (pratensein). The structure of the new isoflavone was elucidated by 1D and 2D homonuclear and heteronuclear NMR spectroscopy and by comparison with published data for closely related compounds.

Isoflavonoids of the leguminosae

Isoflavonoids are found predominantly in subfamily Papilionoideae of the Leguminosae. This review describes more than 420 new examples of Leguminosae isoflavonoids, giving details of their source, identification, biological activity, synthesis, and ecological or chemosystematic significance. Other topics addressed include the application of hyphenated analytical techniques to the characterisation of legume-derived isoflavonoids, and advances made in biosynthetic studies. A checklist of new compounds by species is given, and 404 references are cited.