title: Crystallographic and NMR studies of antiinfective tricyclic guanidine alkaloids from the sponge Monanchora unguifera.
abstract: Three tricyclic guanidine alkaloids, including 1,8a;8b,3a-didehydro-8beta-hydroxyptilocaulin (1), 1,8a;8b,3a-didehydro-8alpha-hydroxyptilocaulin (2) and mirabilin B (3), were identified from the marine sponge Monanchora unguifera. 1,8a;8b,3a-Didehydro-8alpha-hydroxyptilocaulin (2) is a new stereoisomer of 1, the structure of which was elucidated by spectroscopic analysis, comparison of its spectral data with those of 1, and confirmed by X-ray analysis. Compounds 1 and 2 co-crystallized in an unusual perfect order and packed around an approximate inversion center. A mixture of 1 and 2 is active against the malaria parasite Plasmodium falciparum with an IC50 value of 3.8 microg/mL while mirabilin B (3) exhibited antifungal activity against Cryptococcus neoformans with an IC50 value of 7.0 microg/mL and antiprotozoal activity against Leishmania donovani with an IC50 value of 17 microg/mL.
authors.affiliation: Department of Pharmacognosy, School of Pharmacy, University of Mississippi, University, MS 38677, USA.
authors.forename: Hui-ming
authors.initials: HM
authors.lastname: Hua
authors.forename: Jiangnan
authors.initials: J
authors.lastname: Peng
authors.forename: Frank R
authors.initials: FR
authors.lastname: Fronczek
authors.forename: Michelle
authors.initials: M
authors.lastname: Kelly
authors.forename: Mark T
authors.initials: MT
authors.lastname: Hamann
mesh_terms: D000470:Alkaloids / Q000737:chemistry* / Q000494:pharmacology; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology; D000981:Antiprotozoal Agents / Q000737:chemistry / Q000494:pharmacology; D003455:Cryptococcus neoformans / Q000187:drug effects; D003460:Crystallization; D018360:Crystallography, X-Ray; D019791:Guanidine; D020128:Inhibitory Concentration 50; D007893:Leishmania donovani / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D010963:Plasmodium falciparum / Q000187:drug effects; D011161:Porifera / Q000737:chemistry*
chemical_list: D000470:Alkaloids; D000890:Anti-Infective Agents; D000935:Antifungal Agents; D000981:Antiprotozoal Agents; D019791:Guanidine