title: Two new iridoids from selected Penstemon species--antimicrobial activity.
abstract: Eighteen secondary metabolites, belonging to three different chemical groups, were isolated from the methanolic extracts of the aerial parts of selected penstemon plants [Penstemon fruticosus (Pursh) Greene var. fruticosus, Penstemon palmeri Gray and Penstemon venustus Doug. ex Lindl.], and their structures were elucidated on the basis of spectral evidence. Six iridoid glucosides (1-6), three phenylpropanoid glucosides (13-15) and two acetophenone derivatives (16,17), obtained from P. fruticosus, five iridoids (2, 7-10), one phenylpropanoid glucoside (15) and two acetophenones (16, 18), isolated from P. palmeri while three iridoids (2, 11, 12) and three phenylpropanoids (13-15) were identified in P. venustus. Two of the iridoid glucosides (4, 5) from P. fruticosus are new natural products named accordingly as cis- and trans- forms of 10-O-p-methoxycinnamoylaucubin. All isolated compounds, as well as crude methanolic extracts, were evaluated for their antimicrobial activities against six Gram-positive and Gram-negative bacteria and three human pathogenic fungi.
authors.affiliation: a Department of Pharmacognosy with Medicinal Plant Unit , Faculty of Pharmacy, Medical University of Lublin , Lublin , Poland.
authors.forename: Sybilla M
authors.initials: SM
authors.lastname: Zajdel
authors.forename: Konstantia
authors.initials: K
authors.lastname: Graikou
authors.forename: Georgios
authors.initials: G
authors.lastname: Sotiroudis
authors.forename: Kazimierz
authors.initials: K
authors.lastname: Głowniak
authors.forename: Ioanna
authors.initials: I
authors.lastname: Chinou
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology*; D005960:Glucosides / Q000737:chemistry / Q000494:pharmacology; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D057888:Iridoid Glucosides / Q000737:chemistry / Q000494:pharmacology; D039823:Iridoids / Q000737:chemistry* / Q000494:pharmacology*; D015394:Molecular Structure; D032263:Penstemon / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000890:Anti-Infective Agents; D005960:Glucosides; D057888:Iridoid Glucosides; D039823:Iridoids; D010936:Plant Extracts