A new dimeric imidazole alkaloid plasmid conjugation inhibitor from Lepidium sativum. Issue 20 (16th May 2018) - Kwapong, Awo Afi
Graphical abstract: Highlights: A new dimeric imidazole alkaloid was isolated from the seeds of Lepidium sativum. Structure elucidation was achieved by analysis of the NMR spectroscopic and mass spectral data. The new compound, named lepidine AK (1 ), reduced the conjugal transfer of the IncI2 plasmid TP114 to 44.7%. Interestingly, compound1 also promoted the conjugation of the IncN plasmid pKM101 to greater than 120%. Plasmid transfer inhibitors may have utility in reducing the spread of antibiotic resistance genes and bacterial virulence. Abstract: Phytochemical investigation of the methanolic extract of Lepidium sativum seeds led to the isolation of a new compound, named 2-(3-(3-((1 H -imidazol-2-yl)methyl)-5-methoxyphenoxy)benzyl)-1 H -imidazole and given the trivial name Lepidine AK (1 ), along with three known compounds; Lepidine E (2 ), Lepidine B (3 ) and 2-(3-(2-((1 H -imidazol-2-yl)methyl)-6-methoxyphenoxy)benzyl)-1 H -imidazole (4 ). The structures were elucidated based on NMR spectroscopy, UV, IR and high-resolution electrospray ionization mass spectrometry. The isolated compounds were tested for bacterial conjugation inhibition. Lepidine AK (1, 100 μg/mL) reduced the conjugal transfer of the IncI2 plasmid TP114 to 44.7 ± 3.5% but interestingly promoted the conjugation of the IncN plasmid pKM101 to greater than 120%.