Folate derivatives, useful in particular in the context of the folate assay

1. A method of in vitro assaying of folate(s) in a sample, the method comprising:

(a) Contacting the sample with a folate binding partner in the presence of a folate conjugate decarboxylated in the α position and suitable for emitting a signal in a non-radioisotopic competition immunoassay, the folate conjugate corresponding to general formula (III):

wherein:

X is a linear aliphatic saturated hydrocarbon chain containing from 2 to 10 carbon atoms;

Y′ is one of the following general formula (IV) or (V):

wherein R1 is —NH—, —O—, or —S—; and

M is a marker molecule capable of directly or indirectly generating a detectable signal,

wherein the folate conjugate does not consist of either a NSP-DMAE-HD-pteroate compound or a NSP-DMAE-HEG-pteroate compound represented the following formulae (A) and (B):

(b) measuring a signal intensity from the folate conjugate bound with the folate binding partner; and

(c) identifying a concentration of the folate(s) present in the sample by referencing a calibration curve comprising a relationship between the measured signal intensity and the concentration of the folate(s).

2. The method according to claim 1 , wherein X is a linear aliphatic saturated hydrocarbon chain containing from 2 to 7 carbon atoms.

3. A process of in vitro non-radioisotopic competition immunoassay of folate(s) in a biological sample, the process comprising:

a) contacting the biological sample with at least one folate binding partner suitable to in the presence of a with at least one conjugate corresponding to the general formula (III):

wherein

X is a linear aliphatic saturated hydrocarbon chain containing from 2 to 10 carbon atoms;

Y′ is one of the following general formula (IV) or (V):

wherein R1 is —NH—, —O—, or —S—; and

M is a marker molecule capable of directly or indirectly generating a detectable signal;

b) measuring the intensity of the signal; and

c) identifying a concentration of the folate(s) present in the biological sample by referencing a calibration curve comprising a relationship between the measured signal intensity and the concentration of the folate(s).

4. A method for in vitro determination of folate deficiency in a human or animal patient, the method comprising:

a) assaying folate(s) in a biological sample by

i. contacting the biological sample with at least one folate binding partner suitable to in the presence of a with at least one conjugate corresponding to the general formula (III):

wherein

X is a linear aliphatic saturated hydrocarbon chain containing from 2 to 10 carbon atoms;

Y′ is one of the following general formula (IV) or (V):

wherein R1 is —NH—, —O—, or —S—; and

M is a marker molecule capable of directly or indirectly generating a detectable signal

ii) measuring the intensity of the signal;

iii) identifying a concentration of the folate(s) present in the biological sample by referencing a calibration curve comprising a relationship between the measured signal intensity and the concentration of the folate(s) in order to determine the folate(s) concentration in the biological sample;

b) comparing the concentration with a threshold value, the threshold value corresponding to a predetermined folate(s) concentration; and

c) identifying a folate(s) deficiency where the concentration falls below the threshold value.

5. The process according to claim 3 , wherein referencing a calibration curve comprises comparing the measured concentration of the folate(s) with a threshold value corresponding to a predetermined concentration of the folate(s).

6. The method according to claim 2 , wherein the hydrocarbon chain contains from 3 to 5 carbon atoms.

7. The method of claim 1 wherein prior to step (a), the sample is treated to dissociate the folate(s) from other molecules in the sample.

8. The method of claim 1 wherein Y′ is of general formula (IV).

9. The method of claim 1 wherein R1 is NH or O.

10. The method of claim 1 wherein R1 is NH.

11. The method of claim 1 wherein the compound of formula III is selected from the group consisting of

wherein n is an integer between 2 and 10.

12. The method of claim 1 wherein the binding partner is selected from the group consisting of antibodies, antibody fragments, nanofitins, folates receptor or protein; wherein said binding partner binds folates(s).

13. The method of claim 1 wherein M is selected from an enzyme, a chromophore, a fluorescent molecule or an electrochemiluminescent salt.

14. The method of claim 13 wherein M is selected from the group consisting of horseradish peroxidase, alkaline phopatase, β-galactosidase, glucose-6-phosphate dehydrogenase, Alexa, phycocyanins, and organometallic derivatives based on acridinium and ruthenium.