Microbial Pectinase as Potential Tool for Specific and Controlled Drug Delivery System

 

 

Praveen Kumar G, Suneetha V*

Department of Biotechnology, School of Biosciences and Technology, VIT University, Vellore, India

 

ABSTRACT:

A pro-drug is a dormant derivative of a parent molecule of pharmacological importance which necessitates immediate or enzymatic transformation within the body to release its active drug form. They are proved to be more beneficial due to their target selectivity and biological activity. Nowadays, drugs 5-7% of the drugs accepted worldwide and about one-third of drugs approved each year are pro-drugs. Pectin is an edible plant polysaccharide present in plants which was widely utilized for construction of specific drug delivery systems. The main problem faced in drug delivery absence of site specificity of drug release at specific time. Recently, enzymes were used to design sharp-witted drug delivery system that becomes as an emerging field due to its specific advantages which includes substrate specificity and maximum selectivity under minor conditions. Pectinases or pectinolytic enzymes are catalysts which breakdown pectin through hydrolysis or elimination reactions. A Pectinolytic enzyme helps in the controlled release of drug certain time period with site specificity.  This review gives the overview on the action of pectinase on different pectin substrates and its combination with ions and other derivatives coating for controlled and specific colonic drug delivery system.

 

 

 

 

 

INTRODUCTION:

Pectin is an edible plant polysaccharide present in plants which was widely utilized for the making of site-specific delivery of drug systems. Pectin consists of plant cell wall component which is mainly comprises of homogalacturonan region with various degrees of methyl esterification with various degrees of side chains that include arabinans, galactans or arabigalactans which are linked to rhamnogalacturonan regions of the molecule¹. Pectinases or pectinolytic enzymes are the complex group of biocatalysts which degrade the α-1,4 glycosidic bonds of pectin by hydrolysis, de-esterification or elimination reactions. This characteristic of degrading the pectin gives them a prominent place in industrial and other fields².

 

Based on the degree of methyl esterification (DM) the pectin can be divided into greater than 50% are known as high methoxyl pectin (HM) and which has low degree of esterification were known as low methoxyl pectin (LM). In case of low-methoxyl pectin the gelation was formed as a result of ionic linkage with calcium bridges produced by calcium ions (Ca2⁺). On the other hand, highmethoxyl pectin was formed by the hydrophobic interactions between the molecules in combination with hydrogen bonds³. The colon-specific drug delivery system has grabbed their attention for the delivery of different drugs. A drug molecule has to be released to the colon and it should not be degraded when it passed through the gastrointestinal tract⁴. Pectin utilized as stabilizer or texturizer in foods because of their unique property of stability at higher temperature and in acidic conditions. The recent discoverable pectin composites have maximum improved properties in compared to that of pectin-based formulations. It includes: maximal drug loading capacity, early drug release, controlled release of peptide and protein drugs with maximum capacity, broader biocompatibility, mostly fit for their swelling and degradation behaviors for the requirements of engulfed drugs. The quantity of calcium ions included into the pectin gels has greater effect on the gel stability strength and delivering the incorporated drugs⁵.The problems often faced in drug delivery includes (a) minimal solubility of drug and chemical strength inhibiting the drug (b) scanty or different bioavailability due to partial absorption process between biological membranes (c) absence of site specificity⁶. A prodrug is a dormant derivative of a parent molecule of pharmacological importance which necessitates immediate or enzymatic modification within the body to release its vital drug form⁷. Pectin deserved its place in pharmaceutical field as it was favorably helps in the reduction of blood cholesterol level and prophylactic activity by the removal of toxic cations from the body ⁸.  In recent years, enzymes were used to design sharp-witted drug delivery system that becomes as an emerging field due to its specific advantages which includes substrate specificity and maximum selectivity under minor conditions. Meanwhile, every biological and metabolic process involves enzymes so they can be utilized for the enzyme-mediated drug release by its enzymatic action at specific cancerous or inflammated tissues^9-12.Prodrug has been proved to be beneficial for more pharmacologically active compounds in enhancing their physicochemical and biological activity and its target specificity. At present, 5-7% of the drugs accepted worldwide and about 15% of all new drugs approved each year are prodrugs¹³. This review, mainly describes about the pectin its derivatives, combination of pectin with ions and other derivatives and main role of pectinase in drug delivery studies.

 

Pectin-an efficient coating for drug:

The most tantalizing pectin property for its application in industrial area is its gelling activity to form gel. The pectin has been developed to form hydrogels for the drug delivery. In case of high DE pectins, solubility of pectin reduced due to the development of hydrophobic parts which are parallel to the helix axes expand to some extent. The high DE pectins form gels in the existence of maximal concentrations of sugar and its single valency of salts of this pectin exhibit minimum viscosity at certain pH. On the other hand, low DE pectins are hydrophilic in nature and it can only form gel at acidic pH or in the existence of divalent cations. Moreover, insertion of amide groups in low DE pectin will reduce its solubility with increase in their tendency to form gels^14-15.

 

 

Fig.1 Controlled release of Ca-pectinate tablets in pectinase solution

 

 

Fig.2 Shows capsule with pulsatile enzyme-degradable plug¹⁹

 

 

Fig.3(a) Schematic presentation showing molecular arrangement of hydrogel (b) Oblate-spheroid shape of Ca-oligochitosan pectin microsphere (c) Showing microsphere after incubated in simulated gastric fluid (d) Decrease in size of microsphere after incubated in pectinase solution²⁰

 

Calcium pectinate tablets with Pectinase -Specific drug delivery:

The cross-linking agents occupy a significant place in the formulation of pectin-based drug delivery system. Apart from the usage of zinc ions, calcium ions were most probably utilized as cross-linking agent as they enhance the pectin degradation by pectinolytic properties and reveals biological properties which help to inhibit the colon cancer development ¹⁶.More studies have been carried towards the pectin derivatives which can be degraded by enzyme but hydrophobic in nature¹⁷. The Ca-induced molecular synergy of carbohydrate chains are balanced at acidic pH which normally exists in GI tract. Moreover, the introduction of Ca-salts in pectin matrices should increase the sensitivity of enzyme against the microbial flora present in the human and more pectinase has shown to be stimulated or it requires calcium ions for their activity. Earliest study was carried out for the controlled drug delivery system for colon cancer which involves calcium pectinate and pectinase enzyme. The tablets were made with the combination of drug and drug marker with low solubility and it was incubated in buffers containing pectinase enzyme for degradation. The results clearly reveals that the enzyme concentration directly proportional to the maximum release rate as well as fasten the release process¹⁸.

 

Fig.4Slower drug release of polycationic-pectin coated tablets in pectinase solution

 

 

Table.1 Shows GI tract characteristics and drugs for colonic drug delivery^26-27

 

 

Pectinase-Pulsatile controlled drug delivery system:

Apart from controlled release of drugs, pulsatile drug delivery system (PDD) attains more attention because of more advantages compared to that of other delivery systems. PDD system will release the drug immediately with less time period after a particular lag time where no drug has been released. Earlier studies were carried out by the designing of enzymatically controlled plug which involves the compression of pectin and pectinase in different ratios. The results revealed that disintegration time of the plug was directly proportional to the plug weight and their combination ratios. Moreover, the addition of Na-EDTA interrupts the formation of insoluble calcium pectinate formation into the environment. The incorporation of effervescent agents helps in the enhancement of emptying the drug from the capsule¹⁹.

 

Ca-oligochitosan-pectin microspheres in gastric fluid and pectinase:

The Ca-pectin system is often utilized as colonic drug carrier for the controlled drug delivery system. But, the major disadvantage of this system it cannot reach the colon because of the maximal pH and enzymes present in the small intestine. Therefore, recent study was carried out to improve the specific drug release into the colon by cross-linking of Ca-oligochitosan-pectin to form microspheres to carry the drug. The results revealed the hydro gel system was stable when it intact with gastric fluid and pectinase enzyme²⁰.

 

Action of pectinase on pectin and Hydroxypropylmethyl cellulose (HPMC):

The cellulose derivative namely Hydroxypropylmethyl cellulose (HPMC) was used in combination with pectin. The tablets were made from methoxyl pectin and HPMC. The results revealed that broad layer high methoxyl pectin will detain the drug release from tablets to surrounding media. The surrounding solution increase the composite layer breakdown and it makes them as potential one for the colon-specific drug delivery^21-22.

 

Pectinase on pectin-polycations complex:

Polycations which include polylysine and polyacrylate derivatives forms a coacervate when it reacts with pectin (anionic biopolymer). The coecervation was observed by measuring the viscosity change in the solution titrating with one polymer solution into the other. The Eudragit, polyacrylate derivative was titrated with solution of pectin, the viscosity of the mixture solution increased earlier and decreased after it exceeds specific ratio of two polymers. The pectin of 5% is used to neutralize the positive charge in the derivative. The capability of pectin-Eudragit RL complex to inhibit the release of incorporated drugs has been studied. However, high methoxyl pectin (5%) film coating on the complex became impermeable for the pectinase which results in very slow leaching pectin which ultimately causes the slow release of drugs. Thus, pectinase with this derivative combination can be used for specific drug delivery system^23-25.

 

CONCLUSION:

The Drug delivery system which is site-specific to colon after the oral administration becomes major problem due to instability of drug and also the environment which has high pH and enzymatic responsiveness prevailing in the small intestine. The edible pectin can be coated with one of the derivative or ion which makes the drug for the controlled and specific drug delivery at certain time interval. Pectinase or pectinolytic enzyme plays a significant role in controlling the drug release by fastening the process or slower them. Pulsatile pectinase mediated drug delivery system can be efficient one in drug delivery system because of its control and specificity in delivering the drug at defined time interval. Microbial pectinase can be used as an alternative to commercial enzyme which makes the process more beneficial and cost-effective. 

 

ACKNOWLEDGEMENT:

We sincerely like to express our gratitude to Dr G. Viswanathan, founder and Hon’ble Chancellor, VIT University, Vellore, for his constant support and encouragement. We want o express special thanks to Dr. Sekar  Viswanathan, Mr. Sankar Viswanathan , Mr. G.V Selvam   and Dr. Anand V Samuel Vice Chancellor for their constant motivation and help and DST for funding.       

 

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Accepted on 17.05.2017        © RJPT All right reserved