In the denitrifying member of the -Proteobacteria Thauera aromatica, the anaerobic metabolism of aromatic acids such as benzoate or 2-aminobenzoate is initiated by the formation of the coenzyme A (CoA) thioester, benzoyl-CoA and 2-aminobenzoyl-CoA, respectively. Both aromatic substrates were transformed to the acylCoA intermediate by a single CoA ligase (AMP forming) that preferentially acted on benzoate. This benzoateCoA ligase was purified and characterized as a 57-kDa monomeric protein. Based on V max /K m, the specificity constant for 2-aminobenzoate was 15 times lower than that for benzoate; this may be the reason for the slower growth on 2-aminobenzoate. The benzoate-CoA ligase gene was cloned and sequenced and was found not to be part of the gene cluster encoding the general benzoyl-CoA pathway of anaerobic aromatic metabolism. Rather, it was located in a cluster of genes coding for a novel aerobic benzoate oxidation pathway. In line with this finding, the same CoA ligase was induced during aerobic growth with benzoate.
The TLC method developed allows unambiguous identification of three different olibanum samples (Boswellia papyrifera, Boswellia serrata, Boswellia carterii/Boswellia sacra). Evidence on the specific biosynthesis routes of these Boswellia species is reported.
The microsomal prostaglandin E2 synthase (mPGES)-1 is
the terminal enzyme in the biosynthesis of prostaglandin (PG)E2 from cyclooxygenase (COX)-derived PGH2. We previously
found that mPGES-1 is inhibited by boswellic acids (IC50 = 3–30 μM), which are bioactive triterpene acids present
in the anti-inflammatory remedy frankincense. Here we show that besides
boswellic acids, additional known triterpene acids (i.e., tircuallic,
lupeolic, and roburic acids) isolated from frankincense suppress mPGES-1
with increased potencies. In particular, 3α-acetoxy-8,24-dienetirucallic
acid (6) and 3α-acetoxy-7,24-dienetirucallic acid
(10) inhibited mPGES-1 activity in a cell-free assay
with IC50 = 0.4 μM, each. Structure–activity
relationship studies and docking simulations revealed concrete structure-related
interactions with mPGES-1 and its cosubstrate glutathione. COX-1 and
-2 were hardly affected by the triterpene acids (IC50 >
10 μM). Given the crucial role of mPGES-1 in inflammation and
the abundance of highly active triterpene acids in frankincence extracts,
our findings provide further evidence of the anti-inflammatory potential
of frankincense preparations and reveal novel, potent bioactivities
of tirucallic acids, roburic acids, and lupeolic acids.
In a one‐step conversion, commercially available or known compounds are connected to form myrtucommulone A, an anti‐inflammatory and apoptosis‐inducing substance from the common myrtle Myrtus communis (see scheme). This strategy can be used, as well to prepare myrtucommulone libraries.
The synthesis of adenophostin A (2) and two analogues [etheno adenophostin (4) and 8-bromo adenophostin (5)] modified at the adenine moiety, is reported. A combination of NMR analysis and molecular modelling was used to compare their structures in solution and determined that they all adopt very similar conformations. The analogues were tested for their ability to mobilise Ca(2+) from DT40 cells expressing recombinant Type 1 rat Ins(1,4,5)P(3)R which reveals etheno adenophostin as a high affinity fluorescent probe of the Ins(1,4,5)P(3)R. 8-Bromo adenophostin was only slightly less potent. The biological results support our current hypothesis regarding the binding mode of adenophostin A at the Ins(1,4,5)P(3)R, i. e. that a cation-pi interaction between the base moiety and Arg 504 of the receptor in combination with H-bonding may be responsible for the high potency of adenophostin A relative to Ins(1,4,5)P(3).
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