The antibacterial properties of 6-tuliposide B. Synthesis of 6-tuliposide B analogues and structure–activity relationship

Absolute configurations of (−)-hirsutanol A and (−)-hirsutanol C produced by Gloeostereum incarnatum

“…Procedure of determination of antibacterial activities was performed as previously described with a slight modification. 12 Briefly, assay was performed using Mueller-Hinton liquid medium containing 0.3% meat extract, 1.75% Bacto Peptone (BD, Franklin Lakes, NJ, USA) and 0.15% soluble starch. After preculture with Mueller-Hinton liquid medium, 5 ml of test compound solutions and 95 ml of bacterial inoculums were mixed to 5.0Â10 5 CFU ml À1 in 96-well microtiter plates.…”

“…Both 1 and 3 having carbonyl moiety conjugated with exomethylene could have weak antibacterial activities at submillimolar concentrations. 12 Recently X-ray crystal structure of hirsutanol A isolated from the marine fungus Chondrostereum sp. 13 and its biological activities 14 were reported.…”

MurA as a Primary Target of Tulipalin B and 6-Tuliposide B

“…The inhibitory activities of tuliposides and tulipalins against MurA showed a similar trend to the previously reported antibacterial activities. 10) Both (3 0 R)-and (3 0 S)-6-tuliposide Bs or (À)-and (þ)-tulipalin Bs showed almost the same inhibitory activities, while structurally similar tulipalin A showed much less activity than tulipalin Bs and 6-tuliposide Bs. The remaining activities of MurA were dramatically increas- …”

“…10) Based on this SAR, we speculated that the primary target of tulipalin B as an antibacterial agent could be cytoplasmic MurA, like the related compound, cnicin, 11) isolated from Cnicus benedictus L. MurA is the bacterial dual-substrate enzyme that catalyzes the coupling of phosphoenolpyruvate (PEP) and UDP-N-acetylglucosamine (UDP-GlcNAc) to afford enolpyruvated UDP-GlcNAc that is a primitive building unit of peptidoglycan.…”

Molecular Diversity of Tuliposide A-Converting Enzyme in the Tulip

“…5,6) Tulipalins show antimicrobial activities against a broad range of strains of bacteria and fungi, in which tulipalin A functions as an antifungal agent rather than an antibacterial, while tulipalin B functions in the opposite manner. [1][2][3][6][7][8][9][10][11][12][13] In addition, tulipalin A has been reported to exhibit high insecticidal activity. 14,15) Thus tulipalins are considered to serve as a chemical defense for tulip plants against microbial infection and herbivorous insect predation, and tuliposides function as storage forms for active tulipalins.…”