Cytotoxic Spiroepoxide Lactone and Its Putative Biosynthetic Precursor from Goniobranchus Splendidus.
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ABSTRACT:
SUBMITTER: Forster LC
PROVIDER: S-EPMC6044697 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Strigolactones (SLs) are a class of terpenoid plant hormones that regulate shoot branching as well as being known as root-derived signals for symbiosis and parasitism. SL has tricyclic-lactone (ABC-ring) and methyl butenolide (D-ring), and they are connected through an enol ether bridge. Recently, a putative biosynthetic intermediate called carlactone (CL), of which carbon skeleton is in part similar to those of SLs, was identified by biochemical analysis of three biosynthetic enzymes, DWARF27, CAROTENOID CLEAVAGE DIOXYGENASE 7 (CCD7), and CCD8 in vitro. However, CL has never been identified from plant tissues, and the conversion of CL to SLs has not been proven in vivo. To address these questions, we chemically synthesized (13)C-labeled CL. We show that (13)C-labeled CL is converted to (-)-[(13)C]-2'-epi-5-deoxystrigol ((-)-2'-epi-5DS) and [(13)C]-orobanchol, endogenous SLs in rice, in the dwarf10 mutant, which is defective in CCD8. In addition, we successfully identified endogenous CL by using liquid chromatography-quadrupole/time-of-flight tandem mass spectrometry in rice and Arabidopsis. Furthermore, we determined the absolute stereochemistry of endogenous CL to be (11R)-configuration, which is the same as that of (-)-2'-epi-5DS at the corresponding position. Feeding experiments showed that only the (11R)-isomer of CL, but not the (11S)-isomer, was converted to (-)-2'-epi-5DS in vivo. Taken together, our data provide conclusive evidence that CL is an endogenous SL precursor that is stereospecifically recognized in the biosynthesis pathway.
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Project description:Cancer is one of the most important causes of death worldwide. Solid tumors represent the great majority of cancers (>90%) and the chemotherapeutic agents used for their treatment are still characterized by variable efficacy and toxicity. Sesquiterpene lactones are a group of naturally occurring compounds that have displayed a diverse range of biological activities including cytotoxic activity. A series of oxygenated and oxy-nitrogenated derivatives (4?15) from the sesquiterpene lactones cumanin (1), helenalin (2), and hymenin (3) were synthesized. The silylated derivatives of helenalin, compounds 13 and 14, were found to be the most active against tumor cell lines, with GI50 values ranging from 0.15 to 0.59 ?M. The ditriazolyl cumanin derivative (11) proved to be more active and selective than cumanin in the tested breast, cervix, lung, and colon tumor cell lines. This compound was the least toxic against splenocytes (CC50 = 524.1 µM) and exhibited the greatest selectivity on tumor cell lines. This compound showed a GI50 of 2.3 µM and a SI of 227.9 on WiDr human colon tumor cell lines. Thus, compound 11 can be considered for further studies and is a candidate for the development of new antitumor agents.
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Project description:(23S)-23,25-Dihydroxycholecalciferol was converted into at least five metabolites in kidney homogenates prepared from 1,25-dihydroxycholecalciferol-treated chickens. One of these has been positively identified as 23,25,26-trihydroxycholecalciferol by u.v.-absorbance analysis, mass spectrometry and chemical formation of derivatives. 23,25,26-Trihydroxycholecaciferol produces 25-hydroxycholecalciferol-26,23-lactone when incubated in chick kidney homogenates.
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Project description:BackgroundQuorum sensing (QS) networks are more commonly known as acyl homoserine lactone (HSL) networks. Recently, p-coumaroyl-HSL has been found in a photosynthetic bacterium. p-coumaroyl-HSL is derived from a lignin monomer, p-coumaric acid, rather than a fatty acyl group. The p-coumaroyl-HSL may serve an ecological role in diverse QS pathways between p-coumaroyl-HSL producing bacteria and specific plants. Interference with QS has been regarded as a novel way to control bacterial infections. Heterologous production of the QS molecule, p-coumaroyl-HSL, could provide a sustainable and controlled means for its large-scale production, in contrast to the restricted feedback regulation and extremely low productivity of natural producers.ResultsWe developed an artificial biosynthetic process for phenylacetyl-homoserine lactone analogs, including cinnamoyl-HSL, p-coumaroyl-HSL, caffeoyl-HSL, and feruloyl-HSL, using a bioconversion method via E. coli (CB1) in the co-expression of the codon-optimized LuxI-type synthase (RpaI) and p-coumaroyl-CoA ligase (4CL2nt). In addition to this, we show the de novo production of p-coumaroyl-HSL in heterologous host E. coli (DN1) and tyrosine overproducing E. coli (DN2), containing the rpaI gene in addition to p-coumaroyl-CoA biosynthetic genes. The yields for p-coumaroyl-HSL reached 93.4 ± 0.6 and 142.5 ± 1.0 mg/L in the S-adenosyl-L-methionine and L-methionine feeding culture in the DN2 strain, respectively.ConclusionsThis is the first report of a de novo biosynthesis in a heterologous host yielding a QS molecule, p-coumaroyl-HSL from a glucose medium using a single vector system combining p-coumaroyl-CoA biosynthetic genes and the LuxI-type synthase gene.
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