Stereoselective Synthesis of 1-Tuberculosinyl Adenosine; a Virulence Factor of Mycobacterium tuberculosis

Abstract

Despite its status as one of the world’s most prevalent and deadly bacterial pathogens, Mycobacterium tuberculosis (Mtb) infection is not routinely diagnosed by rapid and highly reliable tests. A program to discover Mtb-specific biomarkers recently identified two natural compounds, 1-tuberculosinyl adenosine (1-TbAd) and N6-tuberculosinyl adenosine (N6-TbAd). Based on their association with virulence, the lack of similar compounds in nature, the presence of multiple stereocenters, and the need for abundant products to develop diagnostic tests, synthesis of these compounds was considered to be of high value but challenging. Here, a multigram-scale stereoselective synthesis of 1-TbAd and N6-TbAd is described. As a key-step, a chiral auxiliary-mediated Diels–Alder cycloaddition was developed, introducing the three stereocenters with a high exo endo ratio (10:1) and excellent enantioselectivity (>98% ee). This constitutes the first entry into the stereoselective synthesis of diterpenes with the halimane skeleton. Computational studies explain the observed stereochemical outcome.

Heterologous production of 1-tuberculosinyladenosine inMycobacterium kansasiimodels pathoevolution towards the transcellular lifestyle ofMycobacterium tuberculosis

“…Synthetic 1-TbAd and N 6 -TbAd were produced as described previously (36). Bacterial cultures were grown to mid-log phase and de-clumped as described above, then inoculated into 96-well plates in 200 μl pH-adjusted 7H9 containing 1-TbAd, N 6 -TbAd or vehicle (DMSO) control as indicated.…”

Antibacterial Natural Halimanes: Potential Source of Novel Antibiofilm Agents

“…Both enzymes are new potential targets for the development of novel drugs. Two new natural tuberculosinol derivatives, with an adenosine unit at C15 of the diterpene, have been isolated from M. tuberculosis [19,20], 1-TbAd, 3, and N 6 -TbAd, 4, (Figure 1). It has been observed, in a comparative lipidomic assay between M. tuberculosis and M. bovis that these two diterpenes occur in higher amounts in M. tuberculosis and comprise >1% of all M. tuberculosis lipids, so they could serve as an abundant chemical marker of M. tuberculosis [19,21].…”

“…Antifouling substances with no or reduced toxicity should be discovered or developed [44]. Halimane-purines constitute very interesting natural products for further biological and chemical research owing to their biological activities [20]. Several of these compounds show antibacterial activity, and are structurally similar to the diterpene purines isolated from M. tuberculosis (1-TbAd, 3, and N 6 -TbAd, 4), although in these ones the purine appears glycosylated in a different union with the diterpene [44].…”

“…Rv3377c is a DTC classified as class II that transforms GGPP into tuberculosinyl diphosphate (TPP) with a halimane core [23,57], while Rv3378c is a diterpene synthase that converts TPP into tuberculosinol, 1, or (R/S)-isotuberculosinols, 2, acting as a phosphatase/isomerase [11,17]. [19,20,60] It is probable that the biosynthesis of the diterpene purines isolated from marine organisms follows a similar path to 1-TbAd, 3, and N 6 -TbAd, 4, in which enzyme homologs to Rv3378c could be involved, probably expressed in the genome of the surrounding microbiome around the macro organism.…”

“…Tuberculosinol, 1, isotuberculosinol, 2, and analogues:1-tuberculosinyl adenosine (1-TbAd), 3, and N 6 -tuberculosinyl adenosine (N 6 -TbAd), 4, are halimanes that could be considered VF of M. tuberculosis and tuberculosis illness [18][19][20][22][23][24][25][26][27][28][29]. Nowadays, these compounds are being tested as biomakers for tuberculosis.…”