Apiose activity

The configuration of the single asymmetric carbon atom in this formula was unknown. The customary formulas of apiose osazones would contain no asymmetric carbon atom Vongerichten and Muller could detect no optical activity of the two osazones which they prepared. 

The metabolism of apiose in plants has not been investigated extensively. It has been suggested80 that apiose could give rise to simple terpenes by condensation and reduction. Incubation of [ -,4C]apiose in parsley plants resulted in negligible, but unspecified, amounts of carbon-14 incorporated into apiin.66 The specific activity of the [ -14C]apiose administered was low (5 X 105 d.p.m./jumole) for this reason, the data suggested only that no highly active mechanism is available in parsley for the metabolism of this branched-chain sugar. 

The enzyme catalyzing the transfer of D-apiose from UDP-apiose to 4, 5-dihydroxyflavon-7-yl /3-D-glucopyranoside is commonly called apiin synthetase.7 Activity is measured by the formation of [14C]apiin from UDP-[U-14C]apiose. Apiin synthetase can be measured by the rapid separation and isolation, by poly(ethylenimine)-paper chromatography, of a product of the reaction, namely, [14C] apiin, from UDP-D-[U-14C]xylose and degradation products of UDP-[U-14C]apiose.31 There are reports of the isolation and purification of apiin synthetase from parsley leaves,31 from cell-suspension cultures of parsley,121 and from foxglove (Digitalis purpurea).31 Apiin synthetase isolated from parsley does not require metal ions, NAD+, or other cofactors, and is soluble. It is inhibited by several heavy metals, but not by tetra-N-... 

The value of some nucleosides for use as flavor enhancers,1348 and the possible antiviral or antitumor activity of certain nucleosides,135 have led to the synthesis of purine nucleosides containing analogs of D-apiose in which the ring-oxygen atom of the furanose forms has been replaced.136 Monomolar p-toluenesulfonylation of 3-C-(hydroxy-methyl)-l,2-0-isopropylidene-/3-L-threofuranose (50) yielded 3-C-(hydroxymethyl)-l,2-0-isopropylidene-31-0-p-tolylsulfonyl-/3-L-thre-ofuranose (51) which, through a series of steps, was converted into either methyl 2,3-O-isopropylidene- [3-C-(hydroxymethyl)-4-thio-/3-D-... 

Comparing the activity showed by each active compound, we also would hypothesize even more that apiose moiety joined to C-6 of glucose seems to contribute to COX-2 inhibition more than xylose moiety. Nevertheless, the presence of xylose on this position exerts the same effect on COX-2 inhibition than verbascoside, a diglycoside PPG. 

Also it might compare the activity of forsythoside with poliumoside and angoroside A, all of them with three sugars moieties, but, differing on the last one, apiose, rhamnose and arabinose, respectively, joined at the same position of the second sugar moiety, rhamnose. 

But, in this publication, the authors did not show the effect that the tested PPGs have on the rest of the bacteria that we have mentioned above. Kyriakpoulou and cols,[28] discovered that samioside, is more active than verbascoside against S. aureus, S. epidermidis, Enterobacter cloaceae, E. coli, K. pneumoniae and Pseudomonas aeruginosa. This result could make to think that an additional sugar moiety, in this case, apiose, at C-4 of rhamnosa could contribute to the antibacterial activity. 

However, as mentioned previously, terminal glucose moieties do correlate with the high toxicity of QS-17 and QS-18. Periodate oxidation of QS-18, which presumably destroys the cis vicinal dihydroxyl groups of apiose or galactose, eliminates adjuvant activity. Thus, one or both of these sugars... 

---