WO2014081275A1

WO2014081275A1 - A method for isolating shikimic acid from oil palm waste

Info

Publication number: WO2014081275A1
Application number: PCT/MY2013/000190
Authority: WO
Inventors: Thang YIN MEE; Mohd ZAIREY BIN MOHD ZAIN; David ROSS APPLETON; Neoh BEE KEAT; Teh HUEY FANG; Mohd AMIRON BIN ERSAD; Harikrishna A/L K. KULAVEERASINGAM
Original assignee: Sime Darby Malaysia Berhad
Priority date: 2012-11-26
Filing date: 2013-11-07
Publication date: 2014-05-30
Also published as: MY160083A; BR112015012026A2; CR20150332A; IN2015DN04312A

Abstract

The present invention relates to a method for isolating shikimic acid from oil palm waste using resin adsorption and hydrolysis techniques. The method comprises the steps of subjecting an oil palm waste material to resin adsorption to obtain an adsorbent containing caffeoylshikimic acid isomers, recovering caffeoylshikimic acid isomers in a single fraction, followed by subjecting the single fraction to hydrolysis to obtain shikimic acid and purifying the shikimic acid. The method in accordance with the invention provides good recovery of shikimic acid and enables the shikimic acid to be purified using simple purification method.

Description

A METHOD FOR ISOLATING SHIKIMIC ACID FROM OIL PALM WASTE

FIELD OF THE INVENTION

The present invention relates to a method for isolating shikimic acid from oil palm waste. More particularly, the present invention relates to a method for isolating shikimic acid from oil palm waste using resin adsorption and hydrolysis techniques.

BACKGROUND OF THE INVENTION Shikimic acid is a white crystalline compound of non-nitrogenous acid found naturally in plants. It has two kinds of functional group in the same molecule, i.e. three hydroxyl groups and a carboxylic acid group, which are optically active. In its anionic form, shikimic acid is known as shikimate. Shikimate is an important intermediate compound of the "shikimate pathway" in plants and microorganisms. Further, shikimate is the principal precursor for the synthesis of aromatic amino acids, phenylalanine, tryptophan and tyrosine and other compounds such as alkaloids, phenolics and phenyl propanoids.

Further, based on more recent studies, it is now known that shikimic acid is an essential precursor for the synthesis of Tamiflu, which is the only known drug against avian flu caused by H5N1 virus. With the eminent dangers of avian flu, many pharmaceutical companies are looking to increase production of Tamiflu.

Currently, demands for shikimic acid for production of Tamiflu are met mainly from fruits of Chinese star anise (lllicium verum). The Chinese star anise is known to contain about 2 to 7% of shikimic acid. Unfortunately, the tree of Chinese star anise is not easily cultivable. Therefore, the limited availability of Chinese star anise may impede the production of Tamiflu. With the increasing market demands for Tamiflu, more efforts are put in place to explore alternate sources of shikimic acid. One of the current alternatives provided in the prior art is the production of shikimic acid from genetically engineered Escherichia coli. It is estimated that nearly two-thirds of the demand for shikimic acid is still being sourced from plants, with the remaining one-third obtained from genetically engineered Escherichia coli.

EP1092766 A1 discloses a method of using microorganism belonging to the genus Citrobacter to produce shikimic acid. The method includes the steps of contacting a solution containing shikimic acid with a basic anion exchange resin to adsorb the shikimic acid and eluting the shikimic acid with an aqueous basic solution to thereby purify the shikimic acid.

CN1931823 discloses a process of extracting and separating shikimic acid from aniseed. The process involves water extraction to obtain an extracted solution. The extracted solution is then subjected to an anionic resin column and eluting with sodium hydroxide solution containing the shikimic acid. The solution containing the shikimic acid is desalted in a cationic resin column, concentrated and crystallized in acetone to obtain shikimic acid crystal. Shikimic acid can be purified using different purification methods. JP 2001- 026567 and WO 2001/068891 A1 both disclose a method of purifying shikimic acid by treating a solution containing shikimic acid with an alkali and adsorbing the shikimic acid by an anion exchange resin. Water is then passed through the resin, followed by an aqueous basic solution to recover the shikimic acid. During the elution, dehydroshikimic acid is dehydrated and isomerized to form protocatechuic acid. In this method, shikimic acid can easily be separated from analogous compounds such as dehydroshikimic acid which has a similar chemical structure. There are a number of research efforts going on in identifying caffeoylshikimic acid from plants as one of the alternate sources to recover shikimic acid as caffeoylshikimic acid can be hydrolyzed to shikimic acid. According to Sambanthamurthi et al., "Oil palm phenolics as a source of shikimic acid - a MPOB-MIT collaboration MPOB Information Series", ISSN 15 -7871 , June 2010 (MPOB TT No. 450), shikimic acid and its esters are not commonly found in nature. It is likely that these compounds do not accumulate to an appreciable extent in most plants, owing to their high metabolic turnover. Researchers have found that oil palm phenolic contains three isomers of caffeoylshikimic acid, a group of unique signature phenolics, as major components from the aqueous stream of palm oil mill. Oil palm phenolics also contain numerous phenolic acids such as caffeic acid, protocatechuic acid and p-hydroxybenzoic acid. The major contributors to the total phenolics are caffeoylshikimic acid at 10,800 ± 2400 mg/kg, followed by p-hydroxybenzoic acid at 7000 ± 1000 mg/kg.

Phenolic or caffeoylshikimic acid can be extracted from plants using various methods. US Patent no. 7,387,802 discloses a method for extracting phytochemical such as flavonoids, phenolic acids and hydroxyl acids from palm oil milling effluents using membrane filter. WO 2010/137943A1 discloses a method of extracting caffeoylshikimic acid, protocatechuic acid, hydroxytyrosol and hydroxybenzoic acid from parts of an oil palm including, but are not confined to, vegetation liquor of palm oil milling and palm oil mill effluent, using solid phase extraction approach, followed by semi-preparative high performance liquid chromatography for purification. WO 2011/159144 A1 discloses a method of producing shikimic acid from palm-based waste materials and by-products by purifying shikimic acid from extracts comprising oil palm phenolics, using standard purification methods. The extracts are obtained by pretreating the oil palm with glyphosate and subjecting the extracts to separation using different types of membranes.

Previously reported methods rely on complicated individual purification process for purifying caffeoylshikimic acid isomers and this method is envisaged to be difficult when it is used for large scale production. Other methods known in the art involve direct purification of shikimic acid mixtures from complex extracts. These methods are also not suitable for large scale commercial production as they involve complex extracts. The methods also do not demonstrate the viability of obtaining an optimum source of shikimic acid that could be purified easily on commercial scale. Consequently, with the increase in use and demand of shikimic acid, there is a need in the art to provide a new source of shikimic acid and method to meet the demand, and to address at least one of the above problems, or at least to provide an alternative.

SUMMARY OF THE INVENTION

The above and other problems are solved and an advance in the art is made by a method for isolating shikimic acid from oil palm waste materials in accordance with this invention. A first advantage of the method in accordance with embodiments of this invention is that the method provides good recovery of shikimic acid using resin adsorption and hydrolysis techniques in the method. A second advantage of the method in accordance with embodiments of this invention is that the method enabled the shikimic acid obtained by the method of the present invention to be purified using simple purification process. A third advantage of the method in accordance with embodiments of this invention is that the simplified purification process enables the method of the present invention to be suitable for use in large scale production of shikimic acid. In accordance with an embodiment of this invention, a method for isolating shikimic acid from oil palm waste material is provided. The method comprises the steps of (i) providing an oil palm waste material; (ii) passing the oil palm waste material through an adsorption resin to obtain an adsorbent containing caffeoylshikimic acid isomers; (iii) washing the adsorbent containing the caffeoylshikimic acid isomers using water; (iv) eluting unwanted polar compounds adsorbed on the adsorbent using a mixture containing water and solvent; (v) recovering caffeoylshikimic acid isomers in a single fraction using a mixture containing water and solvent; (vi) subjecting the single fraction to hydrolysis to obtain shikimic acid; and (vii) purifying the shikimic acid.

In accordance with one embodiment of this invention, the method further comprises centrifuging the oil palm waste material to obtain a supernatant and a solid prior to the step of passing the oil palm waste material through the adsorption resin; and subjecting the supernatant to resin or solid phase adsorption to obtain an adsorbent containing caffeoylshikimic acid isomers.

In accordance with some embodiments of this invention, the oil palm waste material is selected from the group comprising a liquid waste material such as separator sludge and aqueous phase of post-3-phase decanter.

In accordance with one embodiment of this invention, the method further comprises contacting the oil palm waste material with at least one member selected from the group consisting of water, an organic solvent or a mixture thereof to obtain an extract prior to the step of passing the oil palm waste material through an adsorption resin.

In accordance with some embodiments of this invention, the oil palm waste material is selected from the group comprising a solid waste material such as oil palm frond, rachis and decanter cake.

In accordance with one embodiment of this invention, the caffeoylshikimic acid isomers are 3-O-caffeoylshikimic acid, 4-O-caffeoylshikimic acid, and 5-0- caffeoylshikimic acid.

In accordance with some embodiments of this invention, the single fraction is hydrolyzed using alkaline water, alkaline watersolvent mixtures or an alkaline aqueous solution. In accordance with one embodiment of this invention, the single fraction is hydrolyzed using an alkaline aqueous solution.

In accordance with one embodiment of this invention, the method further comprises concentrating the single fraction containing the caffeoylshikimic acid isomers prior to the step of subjecting the single fraction to hydrolysis to obtain the shikimic acid.

In accordance with one embodiment of this invention, the supernatant and the adsorption resin is in a ratio of 1 :1 to 10:1. In accordance with some embodiments of this invention, the shikimic acid is purified using any one of the methods selected from the group consisting of ion exchange resin, reversed phase silica, simulated moving bed technology and countercurrent chromatography.

In accordance with another embodiment of this invention, a shikimic acid isolated from oil palm waste material by the method in accordance with the invention is provided. BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present invention will more clearly understood from the following detailed description taken in conjunction with the accompanying drawings:

Figure 1 shows the results of a separator sludge analysed by HPLC-LTQ- Orbitrap. In particular, Figure 1A shows the total ion chromatogram (TIC) of the separator sludge; Figure 1 B shows a chromatogram at m/z 335; Figure 1C shows the spectra at 9.27 min; Figure 1D shows the spectra at 9.73 min; and Figure 1E shows the spectra at 10.77 min.

Figure 2 shows the results of a decanter cake analysed by HPLC-LTQ-Orbitrap. In particular, Figure 2A shows the TIC of the decanter cake; and Figure 2B shows a chromatogram at m/z 335.

Figure 3 shows the results of an aqueous phase of post 3-phase decanter analysed by HPLC-LTQ-Orbitrap. In particular, Figure 3A shows the TIC of the aqueous phase of post 3-phase decanter; and Figure 3B shows a chromatogram at m/z 335.

Figure 4 shows the results of ethanolic and water extracts of oil palm frond analysed by HPLC-LTQ-Orbitrap. In particular, Figure 4A shows the TIC of the ethanolic extract; Figure 4B shows a chromatogram of the ethanolic extract at m/z 335; Figure 4C shows the TIC of the water extract; and Figure 4D shows a chromatogram of the water extract at m/z 335.

Figure 5 shows the results of an ethanolic and water extracts of oil palm rachis analysed by HPLC-LTQ-Orbitrap. In particular, Figure 5A shows the TIC of the ethanolic extract; Figure 5B shows a chromatogram of the ethanolic extract at m/z 335; Figure 5C shows the TIC of the water extract; and Figure 5D shows a chromatogram of the water extract at m/z 335. Figure 6 shows the HPLC-PDA chromatograms of an aqueous phase of post 3- phase decanter at wavelength 327 to 329. In particular, Figure 6A shows a chromatogram of Fraction C; and Figure 6B shows a chromatogram of Fraction D. Figure 7 shows the total amount of caffeoylshikimic acid isomers (measured in ppm) present in different fractions as compared to that of an original aqueous phase of post 3-phase decanter before separation.

Figure 8 shows the maximum plot of HPLC-PDA of fractions D and E. In particular, Figure 8A is Fraction D and 8B is Fraction E.

Figure 9 shows the amount of shikimic acid (measured in ppm) during hydrolysis reaction. Figure 10 shows the chromatograms of an aqueous phase of post 3-phase decanter (Figure 10A) enriched caffeoylshikimic acid isomers fraction before (Figure 10B) and after hydrolysis (Figure 10C).

DETAILED DESCRIPTION OF THE INVENTION

In a typical palm oil milling process, several operations are involved in extracting crude palm oil from fresh palm oil fruit bunches. The operations include, sterilization, stripping, digestion and pressing, clarification, separation, purification, drying and storage. Palm oil is derived from fleshy mesocarp of the fruit of oil palm (Elaeis guinenensis). Oil palm industry has been recognized for its contribution towards economic growth and rapid development. However, it has also contributed to environmental pollution due to the production of huge quantities of by-products.

The present invention relates to a method for isolating shikimic acid from byproducts or waste materials derived from the palm oil industry. The by-products or waste materials produced in the palm oil industry include, but are not limited to, oil palm trunk, oil palm fronds, empty fruit bunches, palm pressed fibres, palm kernel shells, palm kernel cake, and palm oil mill effluent.

In this invention, the by-products or waste materials derived from oil palm fruit in a palm oil mill may be obtained from any stage of the palm oil milling process and also the waste materials may be obtained from the oil palm estate itself. In some embodiments of the invention, the waste materials include, but are not limited to, solid waste materials such as oil palm frond, rachis and decanter cake; and liquid waste materials such as separator sludge (centrifuged sludge) and aqueous phase of post 3-phase decanter.

The term "decanter cake" as used herein refers to a by-product obtained from palm oil milling decantation process. The term "separator sludge" or "centrifuged sludge" as used herein refers to a sludge obtained directly from a centrifuging decanter, a centrifuging separator and/or a 2-phase decanter of a palm oil mill without undergoing any pretreatment or solid-liquid separation. The term "aqueous phase of post 3-phase decanter" as used herein refers to an aqueous phase of a by-product produced in a palm oil milling decantation process. The method in accordance with this invention comprises the steps of passing a waste material derivable from oil palm fruit in a palm oil mill (or an oil palm mill waste material) through an adsorption resin to obtain an adsorbent containing caffeoylshikimic acid isomers. The resin for use in this invention can be any hydrophobic resin, such as an aromatic or modified aromatic resin, for example, sepabeads® and diaion®, or reversed phase silica, such as C18 derivatized silica. In one embodiment of the invention, the caffeoylshikimic acid isomers are 3-O-caffeoylshikimic acid, 4-O-caffeoylshikimic acid, and 5-O-caffeoylshikimic acid (dactylific acid). The method of the present invention can be applied to reconstituted aqueous solutions of other waste materials from oil palm mills which contain caffeoylshikimic acid isomers. In a preferred embodiment of the invention, the waste material is an aqueous phase of post 3-phase decanter. In another preferred embodiment, the waste material is a separator sludge. The adsorbent containing the caffeoylshikimic acid isomers is washed and eluted to remove unwanted polar compounds adsorbed on the adsorbent. The adsorbent can be washed and eluted with water and/or watersolvent mixture in a ratio from 100:0 to 50:50, depending on the type of adsorbent used. The solvent suitable for use in this invention includes, but is not limited to, any one of methanol, ethanol, acetonitrile and any other suitable water miscible solvent. Preferably, methanol or ethanol is used. In the embodiment where liquid waste material is used, the ratio of adsorbent to volume of liquid waste material is in the range from 1 :1 to 1 :5 (weight/volume), preferably 1 :2 to 1 :3. After the unwanted polar compounds are removed from the adsorbent, the caffeoylshikimic acid isomers on the adsorbent are recovered in a single fraction using water or a mixture of water and solvent in appropriate amount. Preferably, the water to solvent ratio ranges from 60:40 to 0:100, more preferably, 60:40 to 30:70, and most preferably 50:50 to 40:60, depending on the type of adsorbent used. The solvent suitable for use includes, but is not limited to, any one of methanol, ethanol, acetonitrile or any other suitable water miscible solvent. Preferably, methanol or ethanol is used. in one embodiment of the invention, the single fraction containing the caffeoy!shikimic acid isomers may be dried before the single fraction undergoes hydrolysis, to concentrate the single fraction. The step of drying can be carried out using any suitable methods known in the art. Such methods include, but are not limited to, freeze-drying, evaporation under vacuum or evaporation using heat. In another embodiment, the single fraction may undergo hydrolysis without going through the step of drying.

The single fraction can be hydrolyzed using, for example, alkaline water, alkaline water.solvent mixtures or alkaline aqueous solution.

In one embodiment of the invention, the single fraction is hydrolyzed using alkaline aqueous solution. Suitable alkaline aqueous solution includes, but is not limited to, sodium hydroxide, potassium hydroxide and other alkali known by one skilled in the art. In a preferred embodiment, the single fraction is hydrolyzed using aqueous sodium hydroxide solution.

The duration of hydrolysis may vary according to the scale of production of the shikimic acid and the concentration of. the solution used. In all cases, the single fraction is hydrolyzed until all the caffeoylshikimic acid isomers are hydrolyzed.

The hydrolysate containing the shikimic acid obtained from the hydrolysis can be purified using any methods known in the art. Preferably, the hydrolysate is purified using reverse phase silica, ion exchange resin, simulated moving bed technology, or countercurrent chromatography.

In one embodiment of the invention, the hydrolysate containing the shikimic acid is purified without having to neutralize the hydrolysate. In another embodiment, the hydrolysate is neutralized prior to subjecting the hydrolysate to acetone precipitation to recover the shikimic acid.

The method in accordance with the invention may further comprise centrifuging the oil palm waste material prior to the step of subjecting the oil palm waste material to resin adsorption, to obtain a supernatant and a solid. The supernatant may then undergo resin adsorption or silica-based adsorption. The types of resin suitable for use in this step include, but are not limited to, hydrophobic resin, such as an aromatic or modified aromatic resin (for example, sepabeads® and diaion®), or reversed phase silica, such as C 8 derivatized silica. The centrifuge used in the method of the present invention can be of any type of centrifuge such as a continuous centrifuge or a batch centrifuge. The operating temperature of the centrifuge is preferably set in the range from 4°C to 60°C, preferably below 10°C. The speed of the centrifuge may vary, as long as it can prolong the operating time with slow speed. The ratio of supernatant to adsorption resin used in the adsorption may range from 1 :1 to 10:1 , preferably 2:1 to 3:1 (volume/weight).

The method of the present invention uses resin adsorption and hydrolysis techniques in isolating shikimic acid from oil palm waste materials. Adsorption of the precursor compounds such as caffeoylshikimic acid isomers into a single fraction using, for example, reverse phase silica or ion exchange resin, followed by hydrolysis provide good recovery of shikimic acid from oil palm waste materials and enable the shikimic acid to be purified using simple purification process. The method of the present invention eliminates the need to use complicated and expensive methods for purifying caffeoylshikimic acid isomers prior to converting the caffeoylshikimic acid isomers to shikimic acid in a separate process. The simplified purification processes enable the method of the present invention to be used for large scale isolation of shikimic acid from caffeoylshikimic acid isomers and large scale recovery of caffeoylshikimic acid from the starting materials.

The following examples are provided to further illustrate and describe particular embodiments of the present invention, and are in no way to be construed to limit the invention to the specific procedures, conditions or compositions described therein.

EXAMPLES

Experimental Scope & Data Stock solutions of standard compounds of shikimic acid, caffeic acid and dehydroshikimic acid were prepared in 50% methanol-water. A series of standard solution was injected into a liquid chromatography coupled with triple quadruple mass spectrometer (Triple-Quad)system and a liquid chromatography coupled with photodiode array detector (HPLC-PDA) system, respectively. The areas of the peaks of each standard were used to make the respective standard curves. The mass spectra of caffeoylshikimic acid were confirmed by reference to Jaiswal et a/., " Profiling and Characterization by LC-MSⁿ of the Chlorogenic Acids and Hydroxycinnamoylshikimate Ester in Mate (Ilex paraguariensis)" J. Agric. Food Chem., Vol. 58, No. 9: 5471-5484 (2010) as no standard is available. Caffeoylshikimic acid was reported at m/z 335 in their mass spectra, located in three peaks. All three regioisomers showed in their MS² spectra a base peak at m/z 178.9, corresponding to a caffeic acid fragment (Jaiswal et al., 2010).

In the following examples, few solid and liquid waste materials were selected for caffeoylshikimic acid extraction and determination. The solid waste materials involved were oil palm frond, rachis and decanter cake, and the liquid waste materials involved were separator sludge (centrifuged sludge) and aqueous phase of post-3-phase decanter.

The composition of caffeoylshikimic acid was determined using liquid chromatography coupled with photodiode array detector (HPLC-PDA) or liquid chromatography coupled with LTQ-Orbitrap mass spectrometer (HPLC-LTQ- Orbitrap). The composition of caffeoylshikimic, shikimic, caffeic and dehydroshikimic acids was determined using liquid chromatography coupled with triple quadruple mass spectrometer (Triple-Quad).

Example 1

Separator sludge was collected from palm oil mill and stored at -80°C. 1 mL of thawed separator sludge was filtered with 0.2 prn membrane filter. The sludge was then subjected to HPLC-LTQ-Orbitrap with ESI negative mode to determine the presence of caffeoylshikimic acid in the separator sludge. The total ion chromatogram (TIC) obtained is as shown in Figure 1A and the chromatogram at m/z 335 is as shown in Figure 1 B. Three peaks were found at retention times of about 9.3, 9.7, and 10.7 minutes, representing 3-O-caffeoylshikimic acid, 4-0- caffeoylshikimic acid, and 5-O-caffeoylshikimic acid, respectively. The mass spectra of each peak are as shown in Figures 1C, 1 D and 1 E, with the base peak at m/z 335. These peaks affirm the presence of caffeoylshikimic acid isomers in separator sludge.

Example 2

A solid or cake of post 3-phase decanter was collected from palm oil mill and stored at -80°C. 1 g of thawed decanter cake was mixed with 1 ml_ of 50% methanol-water, vortex for 1 minute. The sample was then centrifuged at 12,000 rpm for 1 minute. The supernatant was filtered with 0.2 pm membrane filter and then subjected to HPLC-LTQ-Orbitrap analysis to determine the presence of caffeoylshikimic acid isomers in the cake of decanter. The TIC obtained is as shown in Figure 2A and the chromatogram at m/z 335 is as shown in Figure 2B. Three peaks were found in Figure 2B at retention times of 9.28, 9.71 , and 10.73 minutes, representing 3-O-caffeoylshikimic acid, 4-O-caffeoylshikimic acid, and 5- O-caffeoylshikimic acid, respectively. These peaks affirm the presence of caffeoylshikimic acid isomers in the cake of decanter.

Example 3 An aqueous phase of post 3-phase decanter was collected from palm oil mill and stored at -80°C. 1 mL of thawed aqueous sample was filtered with 0.2 pm membrane filter. The sample was then subjected to HPLC-LTQ-Orbitrap with ESI negative mode to determine the presence of caffeoylshikimic acid in the aqueous phase of decanter. The TIC obtained is as shown in Figure 3A and the chromatogram at m/z 335 is as shown in Figure 3B. Three peaks were found in Figure 3B at retention times of 9.31 , 9.72, and 10.75 minutes, representing 3-O- caffeoylshikimic acid, 4-O-caffeoylshikimic acid, and 5-O-caffeoylshikimic acid, respectively. These peaks affirm the presence of caffeoylshikimic acid isomers in the aqueous phase of decanter. Example 4

Oil palm frond was collected from oil palm estate and was air dried, separated from rachis, and ground to about 100 pm. 3 kg of the ground frond were extracted with hexane, followed by dichloromethane. Subsequently, the residual were extracted with ethanol, followed by water. 9 litre of solvent were used for every extraction. Each extraction was carried out for three days. Each solvent extraction was repeated twice before changing to a more polar solvent. 0.1 g of dried ethanolic extract and 0.1 g of dried water extract of oil palm frond were each dissolved in 1 mL of 50% methanol-water, respectively. Each extract was then filtered with 0.2 pm membrane filter before the extract was subjected to HPLC-LTQ-Orbitrap to determine the presence of caffeoylshikimic acid. The TIC of the ethanolic extract and the water extract are as shown in Figures 4A and 4C respectively. The chromatograms at m/z 335 of the ethanolic extract and the water extract are as shown in Figures 4B and 4D respectively. Traces amount of caffeoylshikimic acid isomers were detected in the ethanolic and water extracts of oil palm frond, represented by three peaks found in Figures 4B and 4D, at retention times 9.30 minutes and 9.71 minutes in Figure 4B, and 10.62 minutes in Figure 4D. These peaks affirm the presence of caffeoylshikimic acid isomers in oil palm frond.

Example 5 Ethanolic and water extracts of rachis were prepared as per Example 4 and analyzed by HPLC-LTQ-Orbitrap to determine the presence of caffeoylshikimic acid. The TIC of the ethanolic extract and the water extract obtained from rachis are as shown in Figures 5A and 5C respectively. The chromatograms at m/z 335 of the ethanolic extract and the water extract are as shown in Figures 5B and 5D respectively.

From the chromatograms, we can see that significant amounts of caffeoylshikimic acid isomerswere detected in ethanolic and water extracts of oil palm rachis. Example 6

About 2000 mL of aqueous phase of post 3-phase decanter (similar to the one used in Example 3) was subjected to about 900 g of sepabead® SP207 separation (180 mm x 80 mm i.d.) to recover the caffeoylshikimic acid isomers from the aqueous phase of post 3-phase decanter. A total of 4 fractions, A to D were obtained. The solvent system used in the separation is as shown in Table 1. The fractions were dried and then subjected to HPLC-PDA for analysis. Caffeoylshikimic acid isomers were detected in fractions C and D as shown in Figures 6A and 6B. However, elution through the column was difficult due to blockage caused by the fruits debris found in this aqueous sample. This example shows the concentration and recovery of caffeoylshikimic acid isomers into one sample.

Table 1 : Solvent system for separation of aqueous phase of post 3-phase decanter using sepabead® SP207.

Example 7

About 3,000 mL of the supernatant of aqueous phase of post 3-phase decanter obtained via centrifugation were subjected to sepabead® SP207 separation (200 mm x 80 mm i.d.) to recover caffeoylshikimic acid isomers. A total of fractions A to F were obtained. The solvent system used in the separation is as shown Table 2

Table 2: Solvent system used for separation of supernatant obtained from centrifuging aqueous phase of post 3-phase decanter. Fraction Methanol:Water Volume (ml_)

A 0:100 3000

B 0:100 3000

C 30:70 3000

D 50:50 3000

E 60:40 3000

F 70:30 3000

The fractions were analyzed by HPLC-PDA without drying. The total amount of caffeoylshikimic acid isomers present in each fraction was as shown in Figure 7. The total amount of caffeoylshikimic acid isomers was calculated based on area obtained from HPLC-PDA standard curve of caffeic acid and relative to the molecular weight of caffeic acid.

From the above results, we can see that most of the caffeoylshikimic acid isomers were collected in fractions D and E (as identified by HPLC-PDA) as compared to original supernatant obtained from centrifuging aqueous phase of post 3-phase decanter before resin adsorption, namely "O" as indicated in Table 3 and Figure 7. A total of about 5.03 g and about 5.75 g of fractions D and E were obtained, respectively. The maximum plot of HPLC-PDA of fraction D and E were as shown in Figures 8A and 8B, respectively.

Table 3: Preliminary indication of relative caffeoylshikimic acid isomers (CSA) present in each fraction as compared to supernatant obtained from centrifuging aqueous phase of post 3-phase decanter (namely O).

Fractions CSA (ppm)

O 141

A 2

B 3

C 17

D 120

E 44

F 4 Example 8

Fraction E of Example 7 (namely, the enriched caffeoylshikimic acid fraction) underwent alkali hydrolysis, followed by purification with sepabead® SP207 (180 mm x 15 mm i.d.).

A total of about 4.6323 g of enriched caffeoylshikimic acid fraction was dissolved in 93 ml_ of 50% methanol and hydrolyzed with 4.7 ml_ of sodium hydroxide with a concentration of 3 mol/L. The hydrolysis reaction was monitored for 5 hours and then overnight by observing the formation of shikimic acid using HPLC-PDA. The results are illustrated in Table 4. Caffeoylshikimic acid was hydrolyzed and the amount of shikimic acid slowly increased throughout the hydrolysis reaction, (see Figure 9).

Table 4: Caffeoylshikimic and shikimic acid contents determined during 5 hours and 22 hours of hydrolysis before neutralization. Zero hour represents the time point where right after sodium hydroxide was added into the CSA solution. ppm

Time (mins) Shikimic Acid CSA

0 21 1972

20 142 1341

40 285 1127

60 400 986

80 494 770

100 510 539

120 637 451

140 687 306

160 721 223

180 748 161

210 797 100

240 848 66

270 772 39

300 951 32

1320 941 19 The shikimic acid obtained after the hydrolysis can be purified by any suitable method known in the art including, but is not limited to, sepabead® SP207, RP18, ion exchange, and simulated moving bed technology. A total of 95 mg of shikimic acid was recovered from 4.63 g (out of a total of 5.75g) of fraction E. This method has the potential of yielding 53 mg of shikimic acid per litre of aqueous phase of post 3-phase decanter.

Example 9

An aqueous phase of post 3-phase decanter (4 L) was centrifuged to obtain a supernatant (3.25 L) and a solid. The supernatant obtained (3 L) was then subjected to resin adsorption using sepabead® SP207 to recover an enriched caffeoylshikimic acid fraction. The centrifuge used in the study was set at 4°C at 10,000 rpm. The aqueous phase of post 3-phase decanter was centrifuged for 10 minutes. During the adsorption, the ratio of supernatant to adsorption resin used was 3:1 (volume/weight).

The adsorbent containing caffeoylshikimic acid was washed with water twice, followed by elution with watermethanol at a ratio of 90:10 thrice until most of the unwanted polar materials were removed. This can be monitored using HPLC- PDA. The amount of water and/or watermethanol used for washing can be the same as the volume of the supernatant of post 3-phase decanter loaded into the adsorption resin, at 3L each elution.

After eluting the unwanted polar compounds adsorbed on the adsorbent, the caffeoylshikimic acid isomers was recovered in a single fraction by eluting a watermethanol mixture (3 L) in a ratio of 50:50 until most of the caffeoylshikimic acid isomers were recovered. This can be monitored using HPLC-PDA. A total of 9 L solvent mixtures of watermethanol was used.

The caffeoylshikimic acid enriched fraction obtained was dried and a part of caffeoylshikimic acid enriched fraction (weight in grams) was dissolved in 20 parts (volume in mL) of 50% methanol-water. The concentrated caffeoylshikimic acid enriched fraction was then hydrolyzed with a part of sodium hydroxide with a concentration of 3 mol/L for about 5 hours to obtain the desired shikimic acid. The shikimic acid obtained is then purified from the hydrolysate using method known in the art, such as anion exchange method.

A total of 233 mg of shikimic acid was recovered from 12.35 g (out of a total of 12.48 g obtained from 3 L of centrifuged aqueous phase of post 3-phase decanter) of enriched caffeoy!shikimic acid fraction. The enriched caffeoylshikimic acid fraction contained more than 3.5% of caffeoylshikimic acid. This method has the potential of yielding 63 mg of shikimic acid per litre of aqueous phase of post 3-phase decanter, with a recovery rate of more than 98% from the total caffeoylshikimic acid in the aqueous phase of post 3-phase decanter.

Figure 10 shows the HPLC-PDA chromatograms of aqueous phase of post 3- phase decanter (Figure 10A), enriched caffeoylshikimic acid fraction before hydrolysis (Figure 10B) and the fraction containing the resulting shikimic acid after hydrolysis (FigurelOC). This method can yield 63 mg of shikimic acid / L of aqueous phase of post 3-phase decanter via purification from the hydrolysate using method known in the art, such as ion exchange resin method, RP18, sepabead® SP207, simulated moving bed technology, etc.

Based on the results obtained in the above Examples, one can see that aqueous phase of post 3-phase decanter contains a relatively higher amount of caffeoylshikimic acid isomers as compared to the other oil palm waste materials. This aqueous solution is relatively free of solid particles and non-polar materials. It therefore presents as an optimum source for the precursors of shikimic acid to be concentrated.

The above is a description of the subject matter the inventor regards as the invention and is believed that others can and will design alternative systems that include this invention based on the above disclosure.

Claims

1. A method for isolating shikimic acid from oil palm waste material, the method comprising the steps of:

(i) providing an oil palm waste material;

(ii) passing the oil palm waste material through an adsorption resin to obtain an adsorbent containing caffeoylshikimic acid isomers;

(iii) washing the adsorbent containing the caffeoylshikimic acid isomers using water;

(iv) eluting unwanted polar compounds adsorbed on the adsorbent using a mixture containing water and solvent;

(v) recovering caffeoylshikimic acid isomers in a single fraction using water or a mixture containing water and solvent;

(vi) subjecting the single fraction to hydrolysis to obtain shikimic acid; and

(vii) purifying the shikimic acid.

2. The method according to claim 1, further comprising:

centrifuging the oil palm mill waste material to obtain a supernatant and a solid prior to step (ii); and

subjecting the supernatant to resin or solid phase adsorption to obtain an adsorbent containing caffeoylshikimic acid isomers.

3. The method according to claim 2, wherein the oil palm waste material is selected from the group consisting of liquid waste materials, such as separator sludge and aqueous phase of post-3-phase decanter.

4. The method according to claim 1 , further comprising:

contacting the oil palm waste material with at least one member selected from the group consisting of water, an organic solvent or a mixture thereof to obtain an extract prior to step (ii).

5. The method according to claim 1 , wherein the oil palm waste material is selected from the group consisting of solid waste materials, such as oil palm frond, rachis and decanter cake.

6. The method according to claim 3, wherein the oil palm waste material is an aqueous phase of post 3-phase decanter.

7. The method according to claim 3, wherein the oil palm waste material is separator sludge.

8. The method according to claim 1 , wherein the caffeoylshikimic acid isomers are 3-O-caffeoylshikimic acid, 4-O-caffeoylshikimic acid, and 5-0- caffeoylshikimic acid.

9 The method according to claim 1 , wherein the single fraction is hydrolyzed using alkaline water, alkaline watersolvent mixtures or an alkaline aqueous solution.

10. The method according to claim 9, wherein the single fraction is hydrolyzed using alkaline aqueous solution.

11. The method according to claim 1 , further comprising:

concentrating the single fraction containing the caffeoylshikimic acid isomers prior to step (vi).

12. The method according to claim 2, wherein the supernatant and the adsorption resin is in a ratio of 1 :1 to 10:1.

13. The method according to claim 1 , wherein the adsorption resin is selected from the group consisting of hydrophobic resin, such as an aromatic or modified aromatic resin or reversed phase silica, such as C 8 derivatized silica.

14. The method according to claim 1 , wherein the shikimic acid is purified using any one of the methods selected from the group consisting of ion exchange resin, reverse phase silica, simulated moving bed technology and countercurrent chromatography.

15. A shikimic acid isolated from oil palm waste material by the method as set forth in claim 1.