With the exception of aminoethanoic acid (glycine), the industrially produced amino acids are chiral and the two isomers (D and L) have different properties in biologically induced reactions. However, chemical synthesis produces equimolar quantities of D- and L- forms and additional expensive steps are required to produce a pure stereoisomer. However, biotechnological routes have the great advantage of producing pure optically active amino acids.
Diaspirin [bis(2-carboxyphenyl) succinate; PN508]and fumaryl diaspirin [bis(2-carboxyphenyl) fumarate; PN517] wereprepared as previously described (). Aspirin is commercially available asacetylsalicylic acid, and the synthesis of the other compounds isas described in supplementary information (provided upon request).The compounds tested are shown in .
To understand the molecular basis for the antitumoureffects of aspirin and identify more effective alternatives, wepreviously synthesised a series of derivatives of the aspirinmolecule. These studies revealed that diaspirin (DiA) and fumaryldiaspirin (F-DiA) inhibit proliferation of CRC cell lines atsignificantly lower concentrations than aspirin (). To extend these studies and identifyfurther lead molecules, we synthesised an additional series ofaspirin derivatives ().Cytotoxicity (MTT) assays demonstrated that at 0.5 mM(pharmacologically relevant dose for aspirin), DiA (PN508) andF-DiA (PN517) and to an even greater extent, isopropylm-bromobenzoylsalicylate (PN529) reduced the viability of SW480 CRCcells (). To investigate thespecificity of compound toxicity in more detail, we tested thecapacity of DiA, F-DiA and PN529 to affect proliferation of anumber of established cell lines ( and ), controlling for any variabilitythat could arise from cell culture conditions through culturing allcells with DMEM as the basal medium. While we noted that culturingSW480 cells in their non-native medium (DMEM rather than L-15medium) reduced the sensitivity of the cells to the compoundstested, DiA and F-DiA in this assay system arguably showed amodicum of specificity towards the other CRC cell lines tested(HCT116 and LoVo), and given our finding that PN529 can inducenecrosis (), we focused ourattention on the anti-proliferative activity of DiA and F-DiA inmore detail and .
The major anti-proliferative effect of aspirin isrecognised to be the induction of apoptosis. However, the mechanismby which DiA and F-DiA act against CRC cells is as yet unknown. Tofurther understand this mechanism, we used Annexin V assays toinvestigate the effects of aspirin derivatives on apoptotic celldeath. We found that both compounds (3 mM) induced a significantincrease in the percentage of SW480 CRC cells undergoing apoptosis,compared to the carrier (DMSO)-treated controls (). This increase in apoptosis wasparalleled by a decrease in the percentage of viable cells,confirming the death-inducing capacities of the agents (data notshown). Time course studies revealed that 3 mM F-DiA mediated asignificant increase in apoptosis within 3 h of treatment (), while a more prolonged (>5 h)exposure was required before DiA-mediated apoptosis was evident(data not shown). In contrast to the diaspirin compounds, aspirinat 3 mM had minimal effect on cell growth/death after an 18-hexposure (data not shown), which is in keeping with previousstudies showing that 5 mM aspirin is required to induce detectableapoptosis of these cells within this time frame (). Taken together, these data indicatethat the diaspirin compounds induce apoptosis of CRC cells and thatthis occurs at a lower concentration than for aspirin and thatF-DiA is the more active of the compounds.
Life can get very confusing!When this reacts with ethanoic anhydride, it is ethanoylated (or acylated, if you want to use the more general term) to give:You might find all sorts of other variants on drawing this as well.This molecule is .Although this reaction can also be done with ethanoyl chloride, aspirin is by reacting 2-hydroxybenzoic acid with ethanoic anhydride at 90°C.
These results suggest that the 40% ethanol extract of mangosteen has potent inhibitory activities of both histamine release and prostaglandin E2 synthesis.
Liu Y, Ju J, Xiao H, et al: Effects ofcombination of calcium and aspirin on azoxymethane-induced aberrantcrypt foci formation in the colons of mice and rats. Nutr Cancer.60:660–665. 2008. : :