Phthiocerol dimycocerosates (PDIMs) and phenolic glycolipids (PGLs) are structurally related lipids noncovalently bound to the outer cell wall layer of Mycobacterium tuberculosis, Mycobacterium leprae, and several opportunistic mycobacterial human pathogens. PDIMs and PGLs are important effectors of virulence. Elucidation of the biosynthesis of these complex lipids will not only expand our understanding of mycobacterial cell wall biosynthesis, but it may also illuminate potential routes to novel therapeutics against mycobacterial infections. We report the construction of an in-frame deletion mutant of tesA (encoding a type II thioesterase) in the opportunistic human pathogen Mycobacterium marinum and the characterization of this mutant and its corresponding complemented strain control in terms of PDIM and PGL production. The growth and antibiotic susceptibility of these strains were also probed and compared with the parental wild-type strain. We show that deletion of tesA leads to a mutant that produces only traces of PDIMs and PGLs, has a slight growth yield increase and displays a substantial hypersusceptibility to several antibiotics. We also provide a robust model for the three-dimensional structure of M. marinum TesA (TesAmm) and demonstrate that a Ser-to-Ala substitution in the predicted catalytic Ser of TesAmm renders a mutant that recapitulates the phenotype of the tesA deletion mutant. Overall, our studies demonstrate a critical role for tesA in mycobacterial biology, advance our understanding of the biosynthesis of an important group of polyketide synthase-derived mycobacterial lipids, and suggest that drugs aimed at blocking PDIM and/or PGL production might synergize with antibiotic therapy in the control of mycobacterial infections. Mycobacterium tuberculosis (Mtb),3 Mycobacterium leprae, and several opportunistic mycobacterial human pathogens (e.g. M. marinum (Mm)) produce two related groups of diesters of ␤-glycol-containing aliphatic polyketides (e.g. phenolphthiocerols and phthiocerols) and polyketide synthase-derived multimethyl-branched fatty acids (e.g. mycocerosic acids) (Fig. 1). One of these groups is represented by phthiocerol dimycocerosates (PDIMs). The other group is represented by phenolphthiocerol dimycocerosates, which are glycosylated compounds generally known as phenolic glycolipids (PGLs). These complex lipids, which are believed to be noncovalently bound constituents of the outer leaflet of the unique mycobacterial outer membrane, are known important effectors of virulence (for review, see Ref. 1).Cox et al. (3) and Camacho et al.(2) independently demonstrated in 1999 that loss of PDIMs in PGL-deficient Mtb strains correlates with attenuation in animal models of tuberculosis. It has also been documented that production of PGLs confers a hyperlethality phenotype to PDIM-producing Mtb in murine disease models (4). Since these seminal reports, an overwhelming body of evidence has accumulated demonstrating that PDIMs and PGLs play key roles in virulence and host-pathogen interaction ...

Nine compounds have been isolated from the ethyl acetate soluble fraction of C. sinensis, namely protocatechuic acid (1), trans-caffeic acid (2), methyl rosmarinate (3), rosmarinic acid (4), kaempferide-3-O-β-D-glucopyranoside (5), kaempferol-3-O-β-D-glucopyranoside (6), quercetin-3-O-β-D-glucopyranoside (7), kaempferide-3-O-α-L-rhamnopyranosyl (1→6)-β-D-glucopyranoside (8) and kaempferol-3-O-α-L-rhamno-pyranosyl (1→6)-β-D-glucopyranoside (9), all reported for the first time from this species. The structures of these compounds were deduced on the basis of spectroscopic studies, including 1D and 2D NMR techniques. Compounds 1–9 were investigated for biological activity and showed significant anti-inflammatory activity in the carrageen induced rat paw edema test. The antioxidant activities of isolated compounds 1–9 were evaluated by the DPPH radical scavenging test, and compounds 1, 2, 4 and 7–9 exhibited marked scavenging activity compared to the standard BHA. These compounds were further studied for their anti-glycation properties and some compounds showed significant anti-glycation inhibitory activity. The purity of compounds 2–5, 8 and 9 was confirmed by HPLC. The implications of these results for the chemotaxonomic studies of the genus Cordia have also been discussed.

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