mycolactone-b and mycolactone

Topics: Animals; Antineoplastic Agents; Cell Line; Cell Line, Tumor; Cell Survival; Drug Design; Humans; Inhibitory Concentration 50; Macrolides; Mice; Molecular Structure

The pathogenicity of Mycobacterium ulcerans (Buruli ulcer) is closely associated with the secretion of exotoxin mycolactone. The cytotoxicity of mycolactone has been linked to its apoptogenic activity. We explored if low mycolactone concentrations, which are not able to induce apoptosis, can influence other essential activities on two primary human keratinocyte populations, keratinocyte stem cells (KSC) and transit amplifying cells (TAC), and on a human keratinocyte line, HaCaT. We demonstrated that 0.01 and 0.1 ng/ml mycolactone A/B are not able to induce apoptosis in primary human keratinocytes, but interfere with KSC wound repair. Moreover, the same toxin concentrations reduce cell proliferation of KSC and TAC and their ability to adhere to type IV collagen. HaCaT cells are more resistant to the toxin; nevertheless, they show a delayed woud repair when treated with 1 and 10 ng/ml mycolactone A/B. Moreover, these sub-apoptotic concentrations affect their ability to proliferate and adhere to collagen IV. Wound healing is a complex mechanism, which occurs "in vivo" as the outcome of many co-ordinated events. Sub-apoptotic mycolactone concentrations can affect essential mechanisms, which are required to achieve wound repair, such as adhesion, migration and proliferation of human keratinocytes.

Topics: Adult; Apoptosis; Buruli Ulcer; Cell Adhesion; Cell Line; Cell Proliferation; Collagen Type IV; Humans; Keratinocytes; Macrolides; Middle Aged; Mycobacterium ulcerans; Stem Cells; Wound Healing

Mycolactones are complex macrolides responsible for a severe necrotizing skin disease called Buruli ulcer. Deciphering their functional interactions is of fundamental importance for the understanding, and ultimately, the control of this devastating mycobacterial infection. We report herein a diverted total synthesis approach of mycolactones analogues and provide the first insights into their structure-activity relationship based on cytopathic assays on L929 fibroblasts. The lowest concentration inducing a cytopathic effect was determined for selected analogues, allowing a clear picture to emerge by comparison with the natural toxins.

Topics: Animals; Bacterial Toxins; Buruli Ulcer; Fibroblasts; Macrolides; Mice; Molecular Structure; Mycobacterium Infections; Mycobacterium ulcerans; Structure-Activity Relationship

Unprecedentedly efficient and highly (≥98 %) stereoselective syntheses of mycolactones A and B side chains relied heavily on Pd-catalyzed alkenylation (Negishi version) and were completed in 11 longest linear steps from ethyl (S)-3-hydroxybutyrate in 12% and 11% overall yield, respectively, roughly corresponding to an average of 82% yield per step. The synthesis of mycolactone core was realized by using Pd-catalyzed alkenyl-allyl coupling and an epoxide-opening reaction with a trialkylalkenylaluminate as key steps. Fully hydroxy-protected mycolactones A and B of ≥98% isomeric purity were synthesized successfully for the first time. However, unexpected 4:3-5:4 inseparable mixtures of mycolactones A and B were obtained upon deprotection.

Topics: Alkenes; Bacterial Toxins; Catalysis; Lactones; Macrolides; Molecular Structure; Stereoisomerism

Topics: Acyltransferases; Amino Acid Sequence; Bacterial Toxins; Lactones; Macrolides; Mass Spectrometry; Molecular Sequence Data; Molecular Structure; Mycobacterium ulcerans; Polyketide Synthases; Sequence Homology, Amino Acid; Substrate Specificity