AMPHIPHILIC BIOCONJUGATES OBTAINED FROM XYLAN DERIVATIVES

Abstract

The present invention concerns a compound of formula (I): wherein:—n is an integer comprised between 1 and 7;—X.sub.1 is in particular a radical of formula —CH.sub.2—S—(CH.sub.2).sub.k—S—;—A.sub.1 is in particular a linear or branched alkylene radical comprising from 2 to 30 carbon atoms, and—X.sub.2 is in particular an alkoxy group of formula OR.sub.a, wherein R.sub.a is a linear or branched alkyl group comprising from 1 to 10 carbon atoms.

##STR00001##

Claims

1. A compound of formula (I): ##STR00037## wherein: n is an integer comprised between 1 and 15; X.sub.1 is chosen from the group consisting of: a radical of formula (II):
—CH.sub.2—S—(CH.sub.2).sub.k—S—  (II) wherein k is an integer comprised between 2 and 10, and a radical of formula (III) ##STR00038## A.sub.1 is chosen from the group consisting of: a linear or branched alkylene radical A′.sub.1, optionally substituted by at least one hydroxyl group, comprising from 2 to 30 carbon atoms, when X.sub.1 is a radical of formula (II) as defined above, and a radical of formula -A.sub.2-O—, wherein A.sub.2 is a linear or branched alkylene radical, comprising from 2 to 10 carbon atoms, when X.sub.1 is a radical of formula (III) as defined above, X.sub.2 is chosen from the group consisting of: an alkoxy group of formula OR.sub.a, wherein R.sub.a is H or a linear or branched alkyl group comprising from 1 to 10 carbon atoms, when X.sub.1 is a radical of formula (II) as defined above, and a linear or branched alkyl group A.sub.3, optionally substituted by at least one hydroxyl group, optionally comprising at least one double bond, comprising from 2 to 30 carbon atoms, when X.sub.1 is a radical of formula (III) as defined above.

2. The compound of claim 1, of formula (I-1): ##STR00039## wherein n, k, A′.sub.1 and R.sub.a are as defined in claim 1.

3. The compound of claim 1, of formula (I-2): ##STR00040## wherein n, A.sub.2 and A.sub.3 are as defined in claim 1.

4. The compound of claim 2, wherein A′.sub.1 has the formula (IV): ##STR00041## wherein: R is a linear or branched alkyl group comprising from 2 to 15 carbon atoms, and optionally comprising at least one hydroxyl group; and A.sub.4 is a linear or branched alkylene radical comprising from 2 to 15 carbon atoms.

5. The compound of claim 3, wherein A.sub.3 has the following formula (V): ##STR00042## wherein: A.sub.4 is a linear or branched alkylene radical comprising 1 to 10 carbon atoms, optionally substituted by at least one hydroxyl group, and R.sub.3 is a linear or branched alkyl group comprising 1 to 10 carbon atoms, optionally substituted by at least one hydroxyl group.

6. The compound of claim 1, having one of the following formulae: ##STR00043## wherein: R.sub.2 is H or OH; and R.sub.a is as defined in claim 1.

7. The compound of claim 1, wherein n is 3.

8. The compound of claim 1, having one of the following formulae: ##STR00044##

9. A process for the preparation of a compound of formula (I-1) of claim 2, comprising the reaction of a compound of formula (VI): ##STR00045## with a compound of formula (VII): ##STR00046## k, n, A′.sub.1 and R.sub.a being as defined in claim 2.

10. A process for the preparation of a compound of formula (I-2) of claim 3, comprising the reaction of a compound of formula (VIII): ##STR00047## with a compound of formula (IX): ##STR00048## n, A.sub.2, and A.sub.3 being as defined in claim 3.

11. A cosmetic composition comprising at least one compound of formula (I) of claim 1, and a physiologically acceptable vehicle.

12. A pharmaceutical composition comprising at least one compound of formula (I) claim 1, and a pharmaceutically acceptable excipient.

13. A food supplement comprising at least one compound of formula (I) of claim 1.

14. (canceled)

15. A surfactant comprising a compound of formula (I) of claim 1.

Description

EXAMPLES

Example 1

Preparation of Xylooligosaccharides

[0105] Controlled sulfuric acidic hydrolysis of beechwood 4-O-methylglucuronoxylan (MGX) was performed to get well-defined xylooligosaccharides (XOS).

[0106] MGX (Sigma Aldrich; X-4252) was solubilized in sulfuric acidic media (0.7 M) at 50 g/L. The solution was heated at 90° C. for 45 minutes under magnetic stirring. After reaction, the solution was cooled down with ice and neutralized using a saturated barium hydroxide solution. Finally, centrifugation was conducted to remove the salt that precipitated and the supernatant was freeze-dried. XOS were purified by selective ethanol purification (1:9). The purification was done twice before drying the precipitate under vacuum.

[0107] XOS were obtained with 22 wt. % yield and characterized to have around 6 xylose units and only one methylglucuronic acid (MeGlcA) unit per chain positioned at the non reductive end chain.

Example 2

XOS Functionalization by Reductive Amination

[0108] XOS were dissolved in deionized water at 100 g/L.

[0109] 2-aminoethylazide (prepared from 2-chloroethylamine as explained below) or allylamine (Alfa Aesar) (7.5 eq.) was added under magnetic stirring, followed by NaBH.sub.3CN (Sigma Aldrich) (7.5 eq.).

Preparation of 2-aminoethylazide

[0110] 2-chloroethylamine hydrochlorate (Sigma Aldrich) is solubilized in water (133 g/L) at 80° C. Then sodium azide (3 eq., Sigma Aldrich) is added and the mixture is kept under reflux and magnetic stirring for the night. The mixture is cooled to room temperature then to 0° C. using an ice bath. Potassium hydroxide (same amount as 2-chloroethylamine hydrochlorate, Prolabo) is added and after total dissolution, the product is extracted using diethyl ether. Organic phase is dried over magnesium sulfate (Acros Organics), filtered and finally evaporated to obtain 2-aminoethylazide (20 mol.% yield).

[0111] The mixture XOS+2-aminoethylazide or allylamine was stirred at 50° C. for three days. The solution was then precipitated in ethanol three times (1:10) to remove the excess of amine and NaBH.sub.3CN. The product was finally dried under vacuum (random yield between 40 and 80 wt. % due to the purification step).

##STR00029##

Example 3

Thiol Functionalization of Fatty Acid Esters

[0112] Fatty acid esters (FAE) were dissolved in MeOH at 50 g/L. The esters used here are the following: methyloleate (MeOI) (Alfa Aesar) and methylricinoleate (MeRic) (Nu-Chek Prep).

[0113] Ethanedithiol (20 eq, Acros Organics) was added under magnetic stirring, followed by DMPA (0.1 eq.) (Sigma Aldrich). The mixture was stirred under UV irradiation for 15 minutes. The solution was then dried under vacuum. Finally the mixture was purified using flash chromatography (gradient of dichloromethane and methanol) and dried under vacuum (88 wt. % yield).

##STR00030##

Example 4

Thiol-Ene (TE) Coupling

[0114] Functionalized XOS were dissolved in MeOH at 50 g/L the day before to ensure solubilization. Functionalized FAE (15 eq.) and DMPA (0.75 eq.) were added under magnetic stirring in five times every hour while the mixture was stirred under UV irradiation. The mixture was stirred under UV irradiation for 19 hours, i.e. total reaction time of 24 h. The solution was then dried under vacuum. Finally the mixture was purified by washing the mixture two times with EtOH and one time with cyclohexane (72 wt. % yield).

[0115] with Oleate:

##STR00031##

[0116] with Ricinoleate:

##STR00032##

[0117] These TE bioconjugates have been analyzed through NMR, TGA and DSC. NMR analyses were performed in D.sub.2O as well as in CDCl.sub.3.

[0118] In deutered water, one can clearly see the well-defined signals of XOS between 2.8 and 6.1 ppm.

[0119] In deutered chloroform, one can barely see signals from MeOI. Most of bioconjugates have precipitated at the bottom of the NMR tube.

[0120] Then, thermal properties of TE bioconjugates were analyzed though TGA and DSC. TGA chromatograms clearly show that thermal stability of TE bioconjugates is increased in comparison to XOS. This increase can be due to the presence of sulfur. The temperature stability shows that the coupling is effective.

Example 5

Alcyne Functionalization of FAE

[0121] FAE were functionalized in bulk using 3-butyn-1-ol (10 eq., Acros Organics) with TBD as catalyst (0.1 eq., Sigma Aldrich). The mixture was stirred under nitrogen at 100° C. for 4 hours and for 4 hours more at 100° C. under vacuum. The mixture was then purified by adding ethyl acetate and water (4:1). The organic phase is mixed with water two times more and dried over Na.sub.2SO.sub.4. Finally the organic phase is filtrated and evaporated (75 wt. % yield).

[0122] with Oleate:

##STR00033##

[0123] with Ricinoleate:

##STR00034##

Example 6

Azide-Alcyne (AA) Coupling

[0124] XOS were dissolved in DMSO at 100 g/L and stirred for at least few hours in a water bath at 30° C. FAE derivatives (1 eq.) were dissolved in DMSO (volume as low as possible) and added to the solution. After 15 minutes stirring, sodium ascorbate (NaAsc) (3.5 eq) was added. Finally after 10 minutes, CuSO.sub.4 (3.5 eq.) was added. The solution was stirred for 20-25 hours at 30° C. The reaction medium was then dialyzed 4-5 days against milliQ water (100-500 Da membrane) containing EDTA (VWR International) the first 2 days, and finally lyophilized (29 wt. % yield).

[0125] with Oleate:

##STR00035##

[0126] with Ricinoleate:

##STR00036##

[0127] AA bioconjugates have been analyzed through the same techniques as TE ones, i.e. NMR, TGA and DSC. Moreover, AA bioconjugates were also analyzed through IR spectroscopy.

[0128] Analyses of bioconjugates clearly show the disappearance of the N.sub.3 vibration (2,110 cm.sup.−1) meaning that the coupling was effective and that the conversion seems full.

[0129] Spectra also show the appearance of C═O (1730 cm.sup.−1) and C—N (1380 cm.sup.−1) vibrations due to the Huisgen cycloaddition and the appearance of clear signals corresponding to CH.sub.2 vibrations (asymmetric vibrations at 2,920 cm.sup.−1 and symmetric ones at 2,650 cm.sup.−1) of FAE. Then, NMR analyses were performed in D.sub.2O as well as CDCl.sub.3 for both bioconjugates.

[0130] In deutered water—for both bioconjugates—one can clearly see the signals of XOS between 3.1 and 4.7 ppm but the signals of FAE are undefined between 0.6 and 1.8 ppm. Moreover, no signal from aminoethylazide can be seen, confirming, together with IR, that the conversion is full.

[0131] In deutered chloroform—for both bioconjugates—one can see signals from FAE only. Some bioconjugates have precipitated at the bottom of the NMR tube but most of them are left in solution and organized in chloroform with FAE at the outer of the objects.

[0132] Finally, thermal properties of these AA bioconjugates were analyzed though TGA and DSC. For both FAE, TGA chromatograms show that thermal stability of AA bioconjugates is similar to XOS.

[0133] For both FAE, DSC chromatograms show a flat profile for AA bioconjugates as well as for XOS. Because FAE still have a crystallization/fusion behavior after functionalization, it means that there is no free FAE left in the product.

Example 7

Self-Assembly of Copolymers Obtained Using AA Coupling

[0134] The obtained copolymers are amphiphilic with a HLB of 15 (Davies method). This HLB value is similar to the one of Tween® 80, a surfactant widely employed in cosmetic and food fields.

[0135] The CMC of XOS-AA-Ric has been measured equal to 100 mg/L and the one of XOS-AA-OI equal to 260 mg/L. These copolymers decrease interface tension (water/air) as well as Tween® 80 and increase the wetting of aqueous solution on several surfaces as PET and PTFE. Moreover, XOS-AA-Ric has a foaming capacity. These results promise potential applications as surfactant in cosmetic and food industries.

[0136] Moreover, objects of XOS-AA-Ric and XOS-AA-OI self-assembly were characterized by DLS and TEM: spherical objects are formed with a micellar size under 50 nm. These objects have the fatty chains in their core and the XOS forming the shell. These objects are in dynamic equilibrium. Aggregates (≈500 nm) are also formed and can be eliminated by a simple filtration at 0.45 μm. Interestingly, their assembly is reversible and XOS-AA-Ric and XOS-AA-OI can self-assemble in chloroform forming spherical objects with a micellar size under 50 nm. In that case, XOS are in the core of the objects and fatty chains form the shell. These objects are also in dynamic equilibrium and bigger aggregates (≈1000 nm) are formed and can be eliminated by a simple filtration at 0.45 μm.

[0137] These results promise potential applications in active substance delivery as these polymers are biocompatible and biodegradable.