FR2843027A1 - Plant extracts with high furan lipid content, having antiinflammatory activity, obtained by extracting avocado leaves with liquid, evaporating the extract and heat treating - Google Patents

Abstract

Production of a plant extract (I) with a high furan lipid content comprising subjecting avocado leaves to solid-liquid extraction followed by evaporation under vacuum and heat treatment at 80-120 degres Centigrade, with the steps being carried out in either order, is new. An Independent claim is included for the extracts (I) obtained by the process.

Description

PROCESS FOR OBTAINING AN EXTRACT OF LAWYER LEAVES

RICH IN FURANIC LIPIDS

  The present invention relates to a process for obtaining a plant extract of avocado leaves rich in

furan lipids.

  The avocado comprises, in a known manner, specific lipids of the furan type, the main component of which is a linoleic furan. Thus, "By avocado furan lipids" is meant according to the invention the components corresponding to the formula

GOLD

  in which R is a straight C11-Cl9, preferably C13-C17, saturated hydrocarbon chain or comprising one or more

  several ethylenic or acetylenic unsaturations.

  These avocado furan lipids have been described in particular in Farines, M. et al, 1995, J. of Am. Oil Chem. Soc.

72, 473.

  Currently, the known synthetic routes for obtaining furan lipids and commonly used depart from

  avocados in the form of fruit as a raw material.

  Given the therapeutic interest of avocado furan lipids for their beneficial and curative action on the connective tissue, especially in inflammatory pathologies such as osteoarthritis, periodontitis and scleroderma, and their high cost in general, it there is therefore a strong interest in finding alternative ways of preparing these lipids

avocado furanics.

  The Applicant has thus developed a process, making it possible to obtain a vegetable extract of avocado leaf rich in furan lipids, namely a

  content varying from 20 to 80% and preferably 30 to 50%.

  This process, the raw material of which consists of avocado leaves, comprises the following stages: - a liquid-solid extraction stage followed by evaporation under vacuum and, - a heat treatment stage between 80 and C. These two steps can be implemented in this

order or in reverse order.

  The avocado leaves can come from avocados belonging to the following varieties: Hass, Fuerte, Ettinger, Bacon, Nabal, Anaheim, Lula, Reed, Zutano, Queen, Criola Selva, Mexicana Canta, Region Dschang, Hall, Booth, Peterson, Collinson Red or Alpha Krome and

  more advantageously to the Hass, Fuerte and Reed varieties.

  Several solvents can be used during the liquid-solid extraction step of the leaves, having possibly previously undergone dehydration. The solvents can be chosen from the group consisting of alkanes, halogenated alkanes, ethers, esters, alcohols, aromatic compounds and supercritical fluids. Preferred, alone or as a mixture, hexane, ethanol, methanol, chloroform,

  dichloromethane, and ethyl acetate.

  The heat treatment step, whether it occurs directly on the leaves or at the plant extract stage, is carried out at temperatures between 80 and 1200C. This heat treatment can last from

5 to 72 hours.

  According to the method of the invention, the heat treatment step can be carried out with or without the presence of a

acid catalyst.

  Acid catalysts in the broad sense are understood to be so-called homogeneous inorganic and organic catalysts such as hydrochloric, sulfuric, acetic or paratoluenesulfonic acids but also, and preferably, heterogeneous solid catalysts such as silica, alumina, silica-aluminas , zirconia, zeolites, acid resins. We will choose in particular the acid aluminas of large specific surfaces,

  ie at least equal to 200 m2 / g.

  The process can also include a step, prior to the liquid-solid extraction, of dehydration of the

avocado leaves.

  The term “dehydration of avocado leaves” is understood more generally to mean all of the techniques known to those skilled in the art and which make it possible to extract water from a compound. Among these techniques, mention may be made of drying under a stream of hot air or under a controlled atmosphere (eg nitrogen), at atmospheric pressure or under vacuum, in a thick layer or thin layer, but also drying by microwaves, drying by spraying, lyophilization and osmotic dehydration in solution (direct osmosis) or in solid phase (eg drying in osmotic bags). In general, the temperature during this dehydration stage will preferably be maintained, whatever the technique used, less than or equal to

800C.

  Furthermore, it is preferred in the context of the present invention to stop dehydration when the humidity

residual reaches the 5% threshold.

  In the context of the present process, for reasons of ease of industrial implementation and for cost reasons, drying in ventilated dryers, in a thin layer and under a stream of hot air, at a temperature between 70 and 750C is prefer. The

  duration of the operation can vary from 5 to 72 hours.

  According to a first variant, the method is implemented according to the following sequence of steps: - Step 1: heat treatment of avocado leaves, - Step 2 liquid-solid extraction of avocado leaves, - Step 3: evaporation under solvent vacuum up

  obtaining a desolvent plant extract.

  According to a second variant, the method is implemented according to the following sequence of steps: - Step 1: liquid-solid extraction of avocado leaves, - Step 2: evaporation of the solvent under vacuum until an extract is obtained desolvent plant,

  - Step 3: heat treatment of the plant extract.

  According to a last variant, the method is implemented according to the following sequence of steps: - Step 1 dehydration of avocado leaves, - Step 2 liquid-solid extraction of avocado leaves, - Step 3: evaporation of the solvent until a plant extract is obtained,

  - Step 4: heat treatment of the plant extract.

  The sheets are advantageously ground before any operation carried out within the framework of the process of the invention. The present invention finally relates to a plant extract of avocado leaves capable of being obtained by the process according to the invention, including according to all of its variants. The following nonlimiting examples illustrate the invention. Example 1: one kilogram of Hass variety avocado leaves is carefully ground. The ground material obtained (320 g) is brought into contact with 2 liters of ethanol and then brought to reflux for 5 hours. Once cooled, the mixture is filtered through a buchner and the cake washed with three times 100 ml of ethanol. The solvent is then evaporated in vacuo using a rotary evaporator, then drawn under vacuum for another hour after total removal of the solvent. The extract obtained is then placed in an oven at 100 ° C. for 24 hours, then analyzed. We

  23 g of extract are obtained according to this process.

  Physico-chemical and chromatographic analysis of this extract gave the following results - Incineration residue: <0.1% - Volatile content: <0.1% - Furan lipid content: 42% Example 2: one kilogram of avocado leaves of the Fuerte variety is carefully ground. The ground product obtained (305 g) is brought into contact with 2 liters of hexane and then brought to reflux for 5 hours. Once cooled, the mixture is filtered through b chner and the cake washed with three times 100 ml of hexane. Once gathered, the

  hexane phases are dried in the presence of Na2SO4.

  The hexane is then evaporated under vacuum using a rotary evaporator, then drawn under vacuum for a further hour after complete removal of the solvent. The extract obtained is then placed in the oven at 1000C for 24 hours,

  then analyzed. 26 g of extract are obtained according to this process.

  The physico-chemical and chromatographic analysis of this extract gave the following results - Incineration residue: <0.1% - Volatile content: <0.1% - Furan lipid content: 46% Example 3: one kilogram of Hass variety avocado leaves is carefully ground. The ground material is brought into contact, with stirring, for 5 hours, with 10 liters of methanol, 10 liters of chloroform and 10 liters of brine (1% NaCl). The mixture is then centrifuged and the solid pellet removed. The lower liquid phase is recovered and then dried over Na2SO4. The solvents are then evaporated under vacuum using a rotary evaporator, then drawn under vacuum for another

  one hour after complete removal of the solvents.

  The extract obtained is then placed in an oven at 100 ° C. for 24 hours, then analyzed. 21 g of extract are obtained according to this process. The physicochemical and chromatographic analysis of this extract gave the following results: - Incineration residue: <0.1% - Volatile content: <0.1% - Furan lipid content: 46% Example 4: a kilogram of Hass variety avocado leaves, is carefully ground. The ground material is then dried in an oven, under a stream of hot air, at 110 ° C. for 24 hours. 302 g of dry matter are then recovered. The latter is then brought into contact with 2 liters of hexane and then brought to reflux for 5 hours. Once cooled, the mixture is filtered through

  b chner and the cake washed with three times 100 ml of hexane.

  The hexane is then evaporated under vacuum using a rotary evaporator, then drawn under vacuum for a further hour after complete removal of the solvent. We obtain

according to this process 31 g of extract.

  The physico-chemical and chromatographic analysis of this extract gave the following results - Incineration residue: <0.1% - Volatile content: <0.1% - Furan lipid content: 41% Example 5: one kilogram of Hass variety avocado leaves is carefully ground. The ground material is then dried in an oven, under a stream of hot air, at 700C for 72 hours. 315 g of dry matter are then recovered. The residual moisture present in the leaves is then 4.8%. This dehydrated material is then brought into contact with 2 liters of hexane and then brought to reflux for 5 hours. Once cooled, the mixture is filtered through a buchner and the cake washed with three times 100 ml of hexane. The hexane is then evaporated under vacuum using a rotary evaporator, then drawn under vacuum for a further hour after complete removal of the solvent. The extract obtained is then placed in an oven at 100 ° C. for 24 hours, then analyzed. We

  23 g of extract are then obtained according to this process.

  The physico-chemical and chromatographic analysis of this extract gave the following results - Incineration residue: <0.1% - Volatile content <0.1% - Furan lipid content 38% Comparative example / Process without extensive heating of the leaves Example: one kilogram of avocado leaves of the Hass variety is carefully ground. The ground material is then dried in an oven, under a stream of hot air, at 600C for 96 hours. 307 g of dry matter are then recovered. The latter is then brought into contact with 2 liters of hexane and then brought to reflux for 5 hours. Once cooled, the mixture is filtered through

  b chner and the cake washed with three times 100 ml of hexane.

  The hexane is then evaporated under vacuum using a rotary evaporator, at 60 ° C., then drawn under vacuum for another hour after complete removal of the solvent. We

  27 g of extract are obtained according to this process.

  Physico-chemical and chromatographic analysis of this extract gave the following results - Incineration residue <0.1% - Volatile content: <0.1% - Furan lipid content: 2% Conclusion: absent extensive heating of the leaves, of the extract obtained or of the extract obtained from the fresh or dehydrated leaves after extraction with a solvent, the final extract obtained contains practically no furan lipids (content much lower than %) -

Claims (12)

claims   1. Method for obtaining a plant extract rich in furan lipids, characterized in that the raw material consists of avocado leaves and the method comprises the following stages: - a liquid-solid extraction stage followed by vacuum evaporation and - a heat treatment step between 80 and 1200C,   these two steps can be implemented in this order or in reverse order.   2. Method for obtaining a plant extract rich in furan lipids, characterized in that the avocado leaves come from avocado trees belonging to the following varieties: Hass, Fuerte, Ettinger, Bacon, Nabal, Anaheim, Lula, Reed, Zutano , Queen, Criola Selva, Mexicana Canta, Region Dschang, Hall, Booth, Peterson, Collinson Red or Alpha Krome.   3. Method for obtaining a plant extract rich in furan lipids according to any one of   claims 1 or 2, characterized in that the   heat treatment is carried out for a period varying between 5 and 72 hours.   4. Method for obtaining a plant extract rich in furan lipids according to any one of   Claims 1 to 3, characterized in that the one or more   appropriate solvents during the liquid solid extraction step are chosen from the group consisting of alkanes, halogenated alkanes, ethers, esters, alcohols, aromatic compounds and supercritical fluids. 5. Method for obtaining a plant extract rich in furan lipids according to claim 4, characterized in that the appropriate solvent (s) during the liquid-solid extraction step are chosen from the group consisting of hexane , ethanol, methanol, chloroform, dichloromethane, and ethyl acetate, taken alone or as a mixture.   6. A method of obtaining a plant extract rich in furan lipids according to claim 1 to 5, characterized in that the method comprises a step prior to extraction, dehydrating the avocado leaves. 7. Method for obtaining a plant extract rich in furan lipids according to claim 6, characterized in that the dehydration is chosen from the group consisting of drying under a stream of hot air or under a controlled atmosphere, drying under pressure atmospheric or vacuum, thick or thin layer, microwave drying, spray drying, lyophilization and osmotic dehydration in solution or in solid phase.   8. A method of obtaining a plant extract rich in furan lipids according to claim 7, characterized in that the dehydration consists of drying in ventilated dryers, in a thin layer and in a stream of air.   hot, at a temperature between 70 and 75 C.   9. Process for obtaining a plant extract rich in furan lipids according to any one of   Claims 1 to 8, characterized in that, the process   is implemented according to the following sequence of steps: - Step 1: heat treatment of avocado leaves, - Step 2: liquid-solid extraction of avocado leaves, - Step 3: evaporation of the solvent under vacuum until   obtaining a desolvent plant extract.   10. Method for obtaining a plant extract rich in furan lipids according to any one of   Claims 1 to 8, characterized in that, the process   is implemented according to the following sequence of steps: - Step 1: liquid-solid extraction of avocado leaves, - Step 2: evaporation of the solvent under vacuum until a desolvented plant extract is obtained,   - Step 3: heat treatment of the plant extract.   11. Method for obtaining a plant extract rich in furan lipids according to any one of   Claims 1 to 8, characterized in that the process   is implemented according to the following sequence of steps - Step 1 dehydration of the avocado leaves, - Step 2 liquid solid extraction of the avocado leaves, - Step 3: evaporation of the solvent under vacuum until a vegetable extract is obtained ,   - Step 4: heat treatment of the plant extract.   12. Vegetable extract of avocado leaves capable of being obtained by the process according to any one of claims 1 to 11.