Phylogeny of Acronychia (Rutaceae) and First Insights into Its Historical Biogeography and the Evolution of Fruit Characters

Macoligophones A-I, prenylated acetophenone dimers and monomers from Maclurodendron oligophlebium

Chemical investigation of the bark of Maclurodendron oligophlebium resulted in the isolation of three prenylated acetophenone (PAP) dimers (1-3) and seventeen monomers (4-20). Among them, macoligophones A-I (1, 2, and 4-10) are previously undescribed. Utilizing chiral column, compounds 1-7 were separated into their individual enantiomers. Compound (-)-3 represents an undescribed levorotatory form of a known PAP dimer, acrotrione. Structurally, compounds 1 and 2 contain an unusual oxidized xanthene moiety featured by an uncommon enol substituent. Compound 8 incorporates a unique highly modified coumarin core, representing the second PAP bearing a C7 side chain. Their structures were determined using a combination of spectroscopic analyses, X-ray crystallography, and quantum chemical ECD calculations. Furthermore, both pairs of dimeric PAP enantiomers, (+)-/(-)-1 and (+)-/(-)-2, displayed moderate antiplasmodial activity against chloroquine-resistant Plasmodium falciparum Dd2 strain. This study not only extends the structural repertoire of this important class of aromatic compounds, but also provides a noteworthy source of inspiration for the discovery of antimalaria drugs.

Prenylated Acetophloroglucinol Dimers from Acronychia trifoliolata: Structure Elucidation and Total Synthesis

The isolation of 12 secondary metabolites, including seven new acetophenone monomers, from the 50% CH3OH/CH2Cl2 extract (N089419-L/6) of Acronychia trifoliolata was reported previously. In the present work, three new prenylated acetophenone dimers (1-3) and five known dimers (4-8) were isolated, and their structures were elucidated by using various NMR spectroscopic techniques and HRMS. Among the new dimers, an unprecedented 4-isobutyl-3-isopropyltetrahydro-2H-pyran ring was observed in the structure of 1. This study is the first to report the formation of a 2H-pyran ring between two prenylated acetophloroglucinols. Only four related dimers have been reported before, and they were formylated phloroglucinol dimers from the family Eucalypteae. Compounds 2 and 3 are acrovestone-like dimers, and the structure of 3 was confirmed by total synthesis. The evaluation of the antiproliferative activity of isolated and synthesized acrovestone-like dimers indicated that a double bond in the prenyl-like moiety as found in the more active compounds might be important for mediating activity, while the pendant isobutyl group seems to be less important.

Phylogeny and biogeography of the pantropical genus Zanthoxylum and its closest relatives in the proto-Rutaceae group (Rutaceae)

Zanthoxylum L. (prickly ash) is the only genus in the Citrus L. family (Rutaceae) with a pantropical distribution. We present the first detailed phylogenetic and biogeographic study of the genus and its close relatives in the proto-Rutaceae group. Our phylogenetic analyses based on two plastid and two nuclear markers show that the genus Toddalia Juss. is nested within Zanthoxylum, that earlier generic and intrageneric classifications need revision, and that the homochlamydeous flowers of the temperate species of Zanthoxylum are the result of a reduction from heterochlamydeous flowers. The biogeographic analyses reveal a Eurasian origin of Zanthoxylum in the Paleocene or Eocene with successive intercontinental or long-range migrations. Zanthoxylum likely crossed the North Atlantic Land Bridges to colonize the Americas in the Eocene, and migrated back to the Old World probably via the Bering Land Bridge in the Oligocene or Miocene. Zanthoxylum also colonized several Pacific Islands and the Hawaiian clade shows phylogenetic incongruence between the plastid and nuclear datasets, suggesting hybridization. The Hawaiian species are one of the rare examples of endemic Hawaiian lineages that are older than the current main islands.