Title of Invention

"A PROCESS FOR THE PREPARATION OF TRANSPARENT SOFT COLLAGEN FILM."

Abstract The present invention relates to a process for the preparation of transparent, soft collagen film. More particularly the present invention provides a process for the preparation of anionically charged transparent collagenous substrate for external application in the medical treatment for eye disease. The process of the present invention is envisaged to have enormous potential application in the pharmaceutical industry for preparing ophthalmic substances in the form of films, which can be applied topically to the cornea or instilled in the space .between the eyeball and lower eyelid for curing eye disease. The novelty and non-obviousness of the present invention lies not only in the treatment of the succinylated collagen solution with organic polar solvent to make the said solution free from air bubble for ensuring transparency, but also in the use of plasticisers to ensure softness of the resulting substance, thereby resulting in a substance suitable for being used as dressing aid in ophthalmic applications.
Full Text The present invention relates to a process for the preparation of transparent, soft collagen film. More particularly the present invention provides a process for the preparation of anionically charged transparent collagenous substrate for external application in the medical treatment for eye disease. The process of the present invention is envisaged to have enormous potential application in the pharmaceutical industry for preparing ophthalmic substances in the form of films, which can be applied topically to the cornea or instilled in the space between the eyeball and lower eyelid for curing eye disease.
A good biomaterial for use in ophthalmology should be thin, pliable, amenable to
sterilisation and relatively inert biologically and chemically and should not undergo
secondary changes after exposure to the drugs employed in ophthalmology. When
used as a dressing material it should be able to prevent infection from air-borne
bacteria, stop flow of body fluids from the wound and help in healing and formation
of uniform granulation tissue. Additionally it should be soft, clear and preferably
more transparent than the normally used biological dressings for open raw wounds.
The implant materials useful for ophthalmology must be clear and transparent.
There has been a practice of using ocular lenses, which are made up of synthetic
polymers, for cataract patients after surgical treatment. Waltman and Kaufman
(Investigative Ophthalmology, 9, 250, 1970) used hydrophilic contact lenses as
devices for maintaining high drug concentration in the anterior chamber of the eye.
Other polymeric devices for drug delivery are soluble ocular inserts, such as the
polyvinyl alcohol inserts (PVAI), the soluble Ophthalmic drug insert (SODI) and
polypeptide devices. Although these polymeric lenses, which are essentially used as
corneal shields, are able to control infections from the air borne bacteria, the major
problem associated with them is the absence of biocompatibility, which are likely to
generate various physiological complications, resulting in delay in healing as well as
curing.
This prompted the researchers to look for a biocompatible material to ensure better as
well as faster healing in ophthalmic treatments. Capozza (Chemical Abstract, 84,
35314s, 1976) prepared an interesting enzymatically degradable pharmaceutical
carrier by using chitin (poly N-acetyl-D-glucosamine), which is an important
structural polysaccharide of invertebrates. In this process (German patent 2,505,
305,1975 ) chitin was enzymatically decomposed to serve as a matrix for the ocular
inserts. The major limitation of this insert is again the compatibility because of its
non-protein origin.
Several attempts have therefore been made to explore the possibility of using a
proteinous source for this purpose. The most important animal protein in this context
is collagen, which exists in animal body in the form of bundles of continuous fibres,
cross linked to various extents, thereby forming almost a continuity within tissues.
Collagen has already been very well recognised as an excellent naturally occuring
biomaterial especially because of its following advantages.
i. High tensile strength
ii. Controllable biodegradation
iii. Haemostatic properties
iv. Low antigenicity
v. Low inflammatory and cytotoxic responses
vi. Ability to promote cellular growth and attachment
Moreover, use of collagenous material is, in general, likely to be a better choice in
ophthalmological applications from the point of view of compatibility, because of the
fact that both cornea and lens of human eye are essentially composed of collagenous
tissue and hence the films made out of collagenous substance would not only exhibit
minimal antigenicity but also behave favourably in respect of its several other
parameters like ion-exchange, reactivity with cells and biodegradability, when used in
the eye.
The main limitation of using unmodified collagen films is the development of opacity
at neutral pH. This is due to aggregation of collagen fibrils at neutral pH. The native
collagen is essentially an amino acid polymer containing many positively and
negatively charged groups. Acid soluble collagen molecules have the unique
capability of being reconstituted as the pH of the solutions is raised to neutrality, when
the clear acidic collagenous solution turns into an opaque neutral mass of
reconstituted collagen fibrils. Collagen fibrillogenesis at neutral pH can be prevented
by chemically modifying collagen molecule to either side of neutrality. Such
modification particularly on epsilon amino groups can be used to prepare clear
solution of collagen at neutral pH. When used internally, it is amenable for absorption
in the living system without causing oedema, allergic reactions and autogenic
reactions. The solution is available in sterile ready to use form.
As reported by Hammer et al (Investigative Ophthalmology and Visual Science, 25,
1329-1332, 1984), succinylated collagen films appear to be more transparent and
biopcompatible in comparison to unsuccinylated collagen films. Moreover, they do
not get folded when used as a corneal shield to cover cornea of the eye. This is why
succinylated collagen films considered to be very useful as a protective cover for
ophthalmic management especially for corneal wounds caused by injury, surgery or
diseases and post operative treatment for cataract surgery.
Olcott and Fraenkel Conrat (Chemical Reviews, 41, 151, 1947) succinylated collagen
by dissolving collagen in acid pH and then raising pH to 9.00 by using NaOH solution
and carried out succinylation with succinic anhydride. The major limitation of the
process, practised hitherto, is that the collagen is likely to be oxidised during the
preparation due to absence of inert atmosphere in the preparation process.
Our copending patent application (1598 DEL99) has obviated this limitation by a
modified process of anionic modification of collagen, whereby insoluble collagen is
treated with nonionic surfactant, flooded with inert gas and then swelled in alkaline
conditions. The swelled mass is treated with proteolytic enzyme and succinylation
was conducted after enzyme deactivation by pH adjustment to 9.0.
The major limitation associated with this succinylated collagen is the presence of air
bubble, which makes the film unsuitable for ophthalmic applications.
Another drawback associated with this succinylated collagen is its lack of softness,
resulting in severe irritation to sensitive eyes, because of pinching of the cornea and
the eyeball by the hard film, thereby rendering the same unsuitable for ophthalmic
applications.
The main object of the present invention is to provide a process for the preparation of
transparent, soft collagen film, which obviates the drawbacks stated above.
Another object of the present invention is to prepare collagenous dressing material
which is very much compatible to human corneal layer.
Yet another object of the present invention is to prepare collagenous ophthalmic
dressing aid which stays unfolded even during movement of eye, essentially being
stuck to the upper portion (mainly cornea) of the eyeball.
Still another object of he present invention is to prepare collagenous dressing material
free from any air bubble to ensure its suitability for ophthalmic applications.
Yet another object of the present invention is to prepare collagenous dressing material,
which is reasonably soft to be used for ophthalmic applications.
Still another object of the present invention is to the use abundantly available
collagenous materials like achilles tendon and foetal bovine skin for preparing the
ophthalmic dressing aid.
Yet another object of the present invention is to prepare succinylated collagen shield
having negative charge at physiology pH of 7.4.
Accordingly the present invention provides a process for the preparation of
transparent, soft collagen film, which comprises
i) preparing succinylated collagen solution process such as herein described,
ii) treating the said succinylated collagen solution with 25 to 50% v/v of organic polar solvent at a temperature in the range of 15-25°C for a period of minimum 24 hrs to get the bubble free solution,
iii) treating the bubble free solution as formed in step (ii) with 0.35 to 0.5% v/v of conventional plasticiser under stirring condition for a period of minimum 2 hrs, to get a homogeneous solution,
iv) subjecting the homogeneous solution, as formed in step (iii) to conventional casting followed by drying by known method at a temperature in the range of 15-25°C for 25-40 hrs to get transparent, soft collagen film.
In an embodiment of the present invention, the organic polar solvent used may be such as ethanol, isopropyl alcohol, either individually or in combination.
In another embodiment of the present invention, the amount of the organic polar solvent used may be in the range of 25 to 50% v/v.
In yet another embodiment of present invention the plasticiser used may be such as glycerol, ethylene glycol, either individually or in combination.
In still another embodiment of present invention, the amount of the plasticizer used may be minimum 0.35 to 0.5% v/v.
The process of the present invention is described below in detail.
The succinylated collagen solution used in this invention is prepared in the following
manner.
A source of collagenous tissue is washed well in water and chopped into smaller pieces, which are minced at 10-20°C. The minced material is then scoured using min.

0.2% w/w of a surfactant, on the weight of a minced collagenous tissue, at a temperature of max 40° C. The scoured mass is then slimed with min 0.2% of sliming agent at 30-40° C. The slimed mass is then washed thoroughly to make the same free from non-coliagenous particles, fat and other chemicals. The resulting stock is treated with min. 0.5-2% w/w, of a proteolytic enzyme on the weight of the minced collagenous tissue at 2-8°C for 12-48 hours, the pH of the bath is adjusted in the range of 2-3.5.
The enzyme treated stock is then homogenised using a conventional homogeniser at a temperature of max.37° C and diluted with 150 - 400% v/v, water to form a collagen solution. The viscous solution, thus formed is treated with min. 5% of a precipitant on the volume of the collagen solution with continuous stirring. The resulting suspension is separated conventionally by centrifuging in the range of 10000 - 20000 rpm at 4 - 8° C and the precipitated collagen is dissolved in 200 - 400% v/v of an acid at a pH in the range of 2-4. The homogenous solution, thus obtained is dialysed against of 0.02 M di sodium hydrogen phosphate solution. The dialysate is centrifuged at 10000 rpm and the precipitate is redissolved in 500 ml of 0.5 M acetic acid and dialysed against distilled water for 10-48 hrs to get pure collagen solution.
The pure collagen solution, thus prepared from a collagenous source, is treated with minimum 0.25%w/v of surfactant under agitating condition for a period of at least 5 minutes under inert atmosphere to form a frothy mass. The frothy mass is reacted with 2.5 - 5.0% w/v of succinic anhydride, dissolved in acetone, in presence of inert atmosphere. The suspension thus formed is subjected to separation by conventional
centrifugation at 10000-15000 rpm to obtain the precipitate, which is dissolved in
100-200% water to get a solution, which is dialysed conventionally to get pure
succinylated collagen solution.
The pure succinylated collagen solution, as obtained above, is treated with 25 to 50%
v/v of organic polar solvent for a period of minimum 24 hrs at a temperature in the
range of 15-25° C under stirring conditions. The resulting mass is then treated with
0.35 to 0.5% v/v, of conventional plasticiser under stirring condition for a period of
minimum 2 hrs to get a homogeneous solution, which is subjected to conventional
casting to any shape and size, followed by drying by known method at a temperature
in the range of 15-25° C for a period of 25-40 hrs to get transparent, soft collagen
film.
The novelty and non-obviousness of the present invention lies not only in the
treatment of the succinylated collagen solution with organic polar solvent to make the
said solution free from air bubble for ensuring transparency, but also in the use of
plasticisers to ensure softness of the resulting substance, thereby resulting in a
substance suitable for being used as dressing aid in ophthalmic applications.
The following examples are given by way of illustration and therefore should not be
construed to limit the scope of the present invention.
Example -1
Hundred grams of foetal calf skin collected from a slaughter house, was thoroughly
washed in plain water to free it from extraneous materials like the surrounding tissues.
The washed stock was then chopped into small pieces of 2cm3 and the cut pieces
were minced in Hobart Meat grinder. The temperature was maintained at 10° C by
mixing crushed ice cubes along with the tendon pieces. The minced mass was then
taken in a bath containing the scouring solution, which was prepared by dissolving
200 mg of ethylene-oxide condensate of nonyl phenol in 300 ml water, with
vigorous stirring. The temperature of the bath was maintained at 37°C and the stirring was continued for 8 hrs.
Two hundred milligrams of sodium peroxide was dissolved in 300 ml of water taken in a beaker and the pH of the solution was adjusted to 10 for preparing a sliming solution. The scoured stock was then added to this sliming solution and stirring was continued for 4 hrs at a temperature of 30° C. The stock was then washed thoroughly with three changes of plain water to remove all the loose non -collagenous particles.
Five grams of crystalline pepsin was added to 200 ml of water taken in a beaker at 6° C with constant stirring. The washed slimed stock was then put into the above enzyme bath with vigorous stirring. The pH of the bath was adjusted to 2 by adding HC1. After a period of 48 hrs, the enzyme treated mass was fed into a polytron homogenisor maintained at 37°C and the homogenisation was done at 2500 rpm for 10 minutes till a viscous solution of collagenous tissue was obtained. The homogenate, thus formed, was taken in a beaker and was diluted with 100 ml of distilled water. 5 g of sodium chloride was then added to the beaker with stirring. When a precipitate of collagen tissue was formed at the bottom of the beaker, the precipitated collagen was centrifuged at 4° C and 10000 rpm and the sediment was then resolubilised in
500 ml of acetic acid at pH 2, while continuously stirring the solution for 90 min, till a clear viscous solution of collagen was obtained. The homogenous solution, thus obtained, was dialysed against 5 lit of 0.02 M di sodium hydrogen phosphate solution. The dialysate was centrifuged at 10000 rpm and the precipitate was redissolved in 500 ml of 0.5M acetic acid and dialysed against 51ts of distilled water for 10 hours to get pure collagen solution.
Five hundred millilitres of this pure collagen solution was taken in a round bottom flask and 1.25g of sodium lauryl sulphate was added to it with continuous shaking, while flooding the solution with nitrogen gas. This process of flooding with the nitrogen was continued for three times to make the flask completely free from oxygen. After a period of 30 minutes, pH of the frothy collagen mass was found to be 6, which was adjusted at 9.0 by adding 10% NaOH solution to the flask. 12.5g of succinic anhydride, dissolved in 500 ml of acetone, was then added to the flask with continuous stirring, maintaining the pH constantly at 9.0 by using 10% NaOH solution.
After completion of succinylation, which was ascertained by the fact that the pH of the solution remained constant at 9.0, 2N HC1 was added to the flask with stirring to bring down the pH to 4.2. The resulting suspension was centrifuged at 10000 rpm and the supernatant was decanted. The precipitate, collected thereby, was washed with water and dialysed against 2 lit of distilled water for 12 hours to get pure succinylated collagen solution.
100 ml of pure succinylated collagen was taken in a beaker. 25 ml of ethanol was added to the beaker under stirring conditions and stirring was continued for a period of 24 hrs at a temperature of 25°C. The resulting mass was then treated with 0.35 ml of glycerol under stirring conditions for a period of 2 hrs at a temperature of 25 °C to get a solution for ophthalmic application. The solution was poured into 10 x 10 cm teflon coated trough and air dried at a temperature of 25°C. The air dried films were taken. 12 mm diameter round discs were then cut using a stainless metal punch for ophthalmic application. Example-II
Hundred grams of Achilles tendon of a freshly slaughtered cow, collected from a slaughter house, was thoroughly washed in plain water to free it from extraneous materials like the surrounding tissues. The washed stock was then chopped into small pieces of 2cm3 and the cut pieces were minced in Hobart Meat grinder. The temperature was maintained at 15° C by mixing crushed ice cubes along with the tendon pieces. The minced mass was then taken in a bath containing the scouring solution, which was prepared by dissolving 300 mg of Sodium laurel sulphate in 300 ml water, with vigorous stirring. The temperature of the bath was maintained at 40°C and the stirring was continued for 3 hrs.
Two hundred milligrams of potassium peroxide was dissolved in 300 ml of water taken in a beaker and the pH of the solution was adjusted to 10 for preparing a sliming solution. The scoured stock was then added to this sliming solution and stirring was continued for 4 hrs at a temperature of 40 °C. The stock was then
washed thoroughly with three changes of plain water to remove all the loose non -collagenous particles.
Two grams of crystalline pepsin was added to 200 ml of water taken in a beaker at 4° C with constant stirring. The washed slimed stock was then put into the above enzyme bath with vigorous stirring. The pH of the bath was adjusted to 2.5 by adding HC1. After a period of 12 hrs, the enzyme treated mass was fed into a polytron homogenisor maintained at 30°C and the homogenisation was done at 2500 rpm for 10 minutes till a viscous solution of collagenous tissue was obtained. The homogenate, thus formed, was taken in a beaker and was diluted with 200 ml of distilled water. 15 g of potassium chloride was then added to the beaker with stirring. When a precipitate of collagen tissue was formed at the bottom of the beaker, the precipitated collagen was centrifuged at 6°C and 5000 rpm and the sediment was then resolubilised in 500 ml of acetic acid at pH 3, while continuously stirring the solution for 90 min, till a clear viscous solution of collagen was obtained.
The homogenous solution, thus obtained, was dialysed against 5 lit of 0.02 M disodium hydrogen phosphate solution. The dialysate was centrifuged at 10000 rpm and the precipitate was redissolved in 500 ml of 0.5 M acetic acid and dialysed against 5 Its of distilled water for 24 hours to get pure collagen solution. Five hundred millilitres of this pure collagen solution was taken in a round bottom flask and 3g of Iso octyl phenoxy polyethoxyethanol, was added to it with continuous shaking, while flooding the solution with nitrogen gas. This process of flooding with the nitrogen was continued for three times to make the flask
completely free from oxygen. After a period of 30 minutes, pH of the frothy collagen
mass was found to be 6, which was adjusted at 9.0 by adding 10% NaOH
solution to the flask. 25 g of succinic anhydride, dissolved in 500 ml of acetone, was then added to the flask with continuous stirring, maintaining the pH constantly at 9.0 by using 10% NaOH solution.
After completion of succinylation, which was ascertained by the fact that the pH of the solution remained constant at 9.0, 2N HC1 was added to the flask with stirring to bring down the pH to 4.2. The resulting suspension was centrifuged at 10000 rpm and the supernatant was decanted. The precipitate, collected thereby, was washed with water and dialysed against 2 lit of distilled water for 12 hours to get pure anionic collagen solution.
100 ml of pure succinylated collagen was taken in a beaker. 50 ml of isopropyl alcohol was added to the beaker under stirring conditions and stirring was continued for a period of 24 hrs at a temperature of 15°C. The resulting mass was then treated with 0.5 ml of ethylene glycol under stirring conditions for a period of 2 hrs at a temperature of 15°C to get a solution for ophthalmic application. The solution was poured into 13 mm teflon coated circular disketes and air dried at a temperature of 15°C. The air dried films were taken for ophthalmic application. Example - III
Hundred grams of Achilles tendon collected from a slaughter house, was preserved at -20 °C for a period of 7 days by adding 10 gms of common salt, was thoroughly washed in plain water to free it from extraneous materials like the surrounding
ligament tissues was thoroughly washed in plain water to free it from extraneous materials like the surrounding ligament tissues and superficial flexor tendon. The washed stock was then chopped into small pieces of 2cm and the cut pieces were minced in Hobart Meat grinder. The temperature was maintained at 10 ° C by mixing crushed ice cubes along with the tendon pieces. The minced mass was then taken in a bath containing the scouring solution, which was prepared by dissolving 200 mg of Ethylene-oxide condensate of nonyl phenol in 300 ml water, with vigorous stirring. The temperature of the bath was maintained at 37° C and the stirring was continued for 8 hrs.
Three hundred milligrams of sodium peroxide was dissolved in 300 ml of water taken in a beaker and the pH of the solution was adjusted to 10 for preparing a sliming solution. The scoured stock was then added to this sliming solution and stirring was continued for 4 hrs at a temperature of 30 ° C. The stock was then washed thoroughly with three changes of plain water to remove all the loose non -collagenous particles.
One gram of crystalline papain was added to 200 ml of water taken in a beaker at
4°C with constant stirring. The washed slimed stock was then put into the above
enzyme bath with vigorous stirring. The pH of the bath was adjusted to 3.5 by adding
HC1. After a period of 48 hrs, the enzyme treated mass was fed into a polytron
homogenisor maintained at 37° C and the homogenisation was done at 2500 rpm for 10 minutes till a viscous solution of collagenous tissue was obtained. The homogenate, thus formed, was taken in a beaker and was diluted with 100 ml of
distilled water. 10 g of sodium chloride was then added to the beaker with stirring. When a precipitate of collagen tissue was formed at the bottom of the beaker, the precipitated collagen was centrifuged at 6°C and 15000 rpm and the sediment was then resolubilised in 500 ml of hydrochloric acid at pH 3.5, while continuously stirring the solution for 90 min, till a clear viscous solution of collagen was obtained. The homogenous solution, thus obtained, was dialysed against 5 lit of 0.02 M di sodium hydrogen phosphate solution. The dialysate was centrifuged at 10000 rpm and the precipitate was redissolved in 500 ml of 0.5M acetic acid and dialysed against 5 Its of distilled water for 48 hours to get pure collagen solution.
Five hundred millilitres of this pure collagen solution was taken in a round bottom flask and 4.5g of ethylene oxide condensate of nonyl phenol, was added to it with continuous shaking, while flooding the solution with organ gas. This process of flooding with the organ gas was continued for three times to make the flask completely free from oxygen. After a period of 30 minutes, pH of the frothy collagen mass was found to be 6, which was adjusted at 9.0 by adding 10% NaOH solution to the flask. 15g of succinic anhydride, dissolved in 500 ml of acetone, was then added to the flask with continuous stirring, maintaining the pH constantly at 9.0 by using 10% NaOH solution.
After completion of succinylation, which was ascertained by the fact that the pH of the solution remained constant at 9.0, 2N HC1 was added to the flask with stirring to bring down the pH to 4.2. The resulting suspension was centrifuged at 10000 rpm and the supernatant was decanted. The precipitate, collected thereby, was washed
with water and dialysed against 2 lit of distilled water for 12 hours to get pure anionic collagen solution.
100 ml of pure succinylated collagen solution was taken in a beaker. 15 ml of ethanol was taken in a beaker and 15 ml of isopropyl alcohol was added to it under stirring conditions for a period of 5 minutes. This mixture was then added to the succinylated collagen solution under stirring conditions and stirring was continued for a period of 24 hrs at a temperature of 20°C. In another beaker 0.2 ml of glycerol was added to 0.2 ml of ethylene glycol. This mixture was added to the succinylated collagen solution under stirring conditions for a period of 2 hrs at a temperature of 20°C to get a solution for ophthalmic application. The solution was poured into 10 x 10 cm teflon coated trough and air dried at a temperature of 20°C. The air dried films were taken. 12 mm diameter round discs were then cut using a stainless metal punch for ophthalmic application. The main advantages of the present invention are the following.
1. Organic polar solvent, used in the present invention, manipulates the solvent air interfacial tensions and helps the air bubbles to migrate to the surface and finally to escape in the atmosphere leaving behind bubble free collagen solution suitable for ophthalmic applications, thereby leaving no air bubble imprints on the dried collagen film resulting in a uniform and transparent film.
2. The film prevents excessive evaporation of fluid and controls other secondary infections and serves as a better scaffolding for re-epithelialisation.
3. The ocular region covered with the film can be constantly inspected without disturbing the film as the film is very thin and highly transparent.
4. The dressing aid of the present invention is very much compatible with human corneal layer at neutral pH conditions.
5. The use of plasticiser makes the dressing aid very soft, rendering it suitable for ophthalmic applications.






We Claim:
1. A process for the preparation of transparent, soft collagen film, which comprises;
i) preparing succinylated collagen solution by process such as herein described,
ii) treating the said succinylated collagen solution with 25 to 50% v/v of organic
polar solvent at a temperature in the range of 15-25°C for a period of
minimum 24 hrs to get the bubble free solution, iii) treating the bubble free solution as formed in step (ii) with 0.35 to 0.5% v/v of
conventional plasticiser under stirring condition for a period of minimum 2
hrs, to get a homogeneous solution, iv) subjecting the homogeneous solution, as formed in step (iii) to conventional
casting followed by drying by known method at a temperature in the range of
15-25°C for 25-40 hrs to get transparent, soft collagen film.
2. A process, as claimed in clam 1, wherein the organic polar solvent used is such as ethanol, isopropyl alcohol, either individually or in combination.
3. A process, as claimed in claims 1 to 2, wherein the plasticiser used is such as glycerol, ethylene glycol, ether individually or in combination.
4. A process for the preparation of transparent, soft collagen film, substantially as herein described with reference to the examples.

Documents:

201-del-2001-abstract.pdf

201-del-2001-claims cancelled.pdf

201-del-2001-claims.pdf

201-del-2001-complete specification (granted).pdf

201-del-2001-correspondence-others.pdf

201-del-2001-correspondence-po.pdf

201-del-2001-description (complete).pdf

201-del-2001-form-1.pdf

201-DEL-2001-Form-2.pdf

201-del-2001-form-4.pdf


Patent Number 195171
Indian Patent Application Number 201/DEL/2001
PG Journal Number 31/2009
Publication Date 31-Jul-2009
Grant Date
Date of Filing 27-Feb-2001
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI-110001, INDIA
Inventors:
# Inventor's Name Inventor's Address
1 PRAVEEN KUMAR SEHGAL CENTRAL LEATHER RESEARCH INSTITUTE, ADYAR, CHENNAI-600020, INDIA.
2 MOHAMED RAFIUDDIN AHMED CENTRAL LEATHER RESEARCH INSTITUTE, ADYAR, CHENNAI-600020, INDIA
3 RAJADAS JAYAKUMAR CENTRAL LEATHER RESEARCH INSTITUTE, ADYAR, CHENNAI-600020, INDIA
4 RAMASAMY SRIPRIYA CENTRAL LEATHER RESEARCH INSTITUTE, ADYAR, CHENNAI-600020, INDIA
PCT International Classification Number A61K 35/12
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA