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Novel Process in Preparation of Deproteinized Natural Rubber Latex

Prapaporn Boonme, Wirach Taweepreda, Wiwat Pichayakorn

Advanced materials research · 2013

Natural rubber latex (NRL) tapped from Hevea brasiliensis is composed of cis-1,4-polyisoprene as the major polymer which provides several desirable physical properties which make it to be interesting in pharmaceutical formulations. However, the International Union of Immunological Societies (IUIS) has reported about latex allergies caused by 14 NRL proteins (Hev b1-14). This problem can be coped with deproteinization of NRL in order to obtain deproteinized natural rubber latex (DNRL). This study aimed to prepare DNRL by novel process which was easy to perform and used pharmaceutical acceptable agents. The obtained DNRL was assayed for remained protein amount in form of nitrogen content by Kjeldahl method. Its physical properties were characterized. Its stability was also physically investigated. The DNRL was tested for the skin irritation in 3 rabbits. It was found that the protein amount of DNRL was 0.257% while the initial protein amount of fresh NRL was 1.531%. Hence, the protein was removed for 83.21%. DNRL had the average pH of 7.27. Both protein content and pH value implied that DNRL should be safe for skin application. DNRL possessed Newtonian flow with low viscosity which should be easy for mixing with other components in the further pharmaceutical formulations. The particle size, polydispersity index (PI), and zeta potential of DNRL were 441.0 nm, 0.240, and -42.53 mV, respectively, indicating narrow size distribution and physical stability. The dry rubber content and total solid content of DNRL were controlled as 39.55% and 40.72%, respectively. The suitable storage condition of DNRL was at 2-8°C in tight containers where DNRL could be kept for longer than 4 months. Very slightly irritation with no allergy caused by DNRL was observed in the tested rabbits. It could be concluded that this deproteinization process was easy and the prepared DNRL by this process was suitable and safe for using in further pharmaceutical and cosmetic formulations.

Improved Deproteinization Process for Protein-Free Natural Rubber Latex

Wiwat Pichayakorn, Jirapornchai Suksaeree, Wirach Taweepreda

Advanced materials research · 2013

Hev b1-14 type proteins in natural rubber latex (NRL) have been identified as allergens in immunogenic responses. Several methods have been developed to reduce these proteins from NRL such as enzyme treatment, centrifugation, creaming, simple or ultrasonic leaching, and chlorination. In this work, the improvement of deproteinization of NRL was developed using the combination of enzyme treatment and leaching processes. The fresh NRL was incubated with 0.2 phr proteolytic alcalase enzyme, and preserved with 2%v/v paraben concentrate in the presence of a 2%v/v sodium lauryl ether sulfate (SLES) as a surfactant at 37°C for 24 hours, and then centrifuged. The upper rubber mass was then leached for three times with either distilled water, a 1%v/v SLES solution, or a mixture of 1%v/v SLES and 2.5%v/v ethanol, and then finally re-dispersed in distilled water. It was found that the increasing process of leaching with either 1%v/v SLES or a mixture of 1%v/v SLES and 2.5%v/v ethanol had the higher efficacy to reduce the remained protein in deproteinized NRL (DNRL). The best deproteinized process was the enzyme treatment and followed by the three times leaching process with a mixture of 1%v/v SLES and 2.5%v/v ethanol, that could completely reduce the proteins in DNRL to 0%. This DNRL had the pH value, viscosity, dry rubber content, and total solid content of 7.41, 13.82 cps, 42.57%, and 44.63%, respectively. Its particle size was 626.23 nm with low polydispersity index of 0.16. The negative charge of SLES could increase the higher negative charge of DNRL to-63.20 mV that exhibited very good physical stability during storage. In conclusions, the combination of enzyme treatment and leaching process with both SLES and ethanol was successful to produce the protein-free DNRL. This DNRL could be further used for several applications including medical skin products.

Cosmetic Pore Packs from Deproteinized Natural Rubber Latex

Wiwat Pichayakorn, Prapaporn Boonme, Wirach Taweepreda

Advanced materials research · 2013

Natural rubber latex (NRL) from Hevea brasiliensis consists of cis-1,4-polyisoprene that have many excellent physical properties such as high elasticity, tensile strength, and easily film-forming. However, some proteins in NRL can cause allergy. Hence, this research aimed to prepare cosmetic pore packs from deproteinized NRL (DNRL) that was prepared in-house by enzyme treatment and centrifugation processes. The properties of DNRL were evaluated in terms of amount of remained protein, pH, particle size, polydispersity index, and zeta potential. This DNRL was then formulated the pore pack products by mixing with the other ingredients and casting to the film form. An appropriate pore pack formulation composed of sodium alginate and polyvinylpyrrolidone K30 mixed with DNRL to produce films with good properties. Hydroxypropylmethylcellulose was also added to another formulation for improving toughness of the films. Both products had similar appearance and physical properties such as thickness, uniformity of weight, pH, tensile strength, and elongation at break, but lower peel strength comparing with the commercial pore pack product. These films showed good flexibility, softness, and toughness. After storage at room temperature for a month, there were no different in appearance and pH that presented good stability. The obtained pore packs also exhibited desirable characteristics with acceptable volunteer satisfactions. However, they should be improved for more adhesiveness in further study. In conclusion, DNRL could be used as major component for cosmetic pore pack preparations.

Separation and Characterization of Minerals from Centrifuged Waste Latex Sludge

Wirach Taweepreda

2013

Preparation and Properties of Electrospun PVC Nanofiber

Kritsada Phatcharasit, Wirach Taweepreda, Kanoktip Boonkerd, Jin Kuk Kim

Advanced materials research · 2013

Nanofibrous membranes based on poly (vinyl chloride) (PVC) were prepared by electrospinning. The morphology of nanofibrous was observed under field emission scanning electron microscope (FE-SEM) and effects of instrument parameters including electric voltage, tip to collector distance, and solution parameters such as PVC concentration and mixed solvent of THF and DMF (50:50) were evaluated. The beads on the fiber were formed with low concentration of PVC. The dielectric constant, thermal properties and crystallinity of the electrospun membranes were characterized by precision LCR meter, and differential thermal analysis (DTA), respectively. It was found that smooth surface of electrospun PVC nanofiber had a high ionic conductivity and their thermal properties were improved comparing with PVC sheet.

Characterization of Lidocaine Transdermal Patches from Natural Rubber Latex

Prapaporn Boonme, Hasleena Boontawee, Wirach Taweepreda, Wiwat Pichayakorn

Advanced materials research · 2013

The mucous liquid of Hevea brasiliensis or Para rubber tree, called natural rubber latex (NRL), composes of cis-1,4-polyisoprene which can form a patch under suitable formulation. In this study, blank and 5% lidocaine-loaded NRL patches were formulated and then characterized for physicochemical properties as well as evaluated in vitro drug release and stability. The patches were observed for their appearances. Surface morphology of the patches was investigated using a SEM. XRD was employed to study the crystallinity of the drug, the patch, and the drug-loaded patch. The extractions of lidocaine-loaded patches were analyzed for drug contents by HPLC. In vitro drug release study was performed using modified Franz diffusion cells. The patches at initial preparation and after kept at 4, 25, and 45 °C for 3 months were investigated for the stability determination. The results suggested that NRL could be used as a main component in pharmaceutical transdermal patches with acceptable physicochemical properties. Lidocaine-loaded NRL patches provided desirable drug release but high storage temperatures could age the patches resulting in darken color and lower release amount.

Properties of Deproteinized Natural Rubber Latex Blended Films with Glycol Penetration Enhancers for Pharmaceutical Applications

Weeraya Simchareon, Thanaporn Amnuaikit, Prapaporn Boonme, Wirach Taweepreda, Wiwat Pichayakorn

Advanced materials research · 2013

The blended film of deproteinized natural rubber latex (DNRL) with hydroxypropyl methylcellulose (HPMC) and dibutylphthalate (DBP) provided good properties that suitable for pharmaceutical applications. However, this film had successfully been confirmed in transdermal use only for high skin permeable drugs. In this study, this film was further modified to look forward on the delivery of a low permeable drug. Glycols, one group of chemical penetration enhancer, were investigated to blend in this film in order to enhance the low permeable drug through the skin. Various concentrations (5, 10, 15, and 20 parts per hundred of rubber (phr)) of ethylene glycol (EG), propylene glycol (PG), and polyethylene glycol 400 (PEG400) were blended with DNRL/HPMC/ DBP mixtures before film construction by solution-casting technique. The modified films were evaluated in thickness, tensile strength, peel strength, tack adhesive, swelling and erosion ratios, moisture uptake, and compatibility. These blended films provided good characters in elasticity, adhesive properties, hydrophilicity, and compatibility. Their thickness could be controlled to be uniform. These new blended films were suitable to use in the further study for low permeable drug delivery through the skin.

Propranolol Hydrochloride Extended-Release Matrix Tablets Using Natural Rubber Latex as Binder

Kamon Panrat, Prapaporn Boonme, Wirach Taweepreda, Wiwat Pichayakorn

Advanced materials research · 2013

Matrix is one of the most interesting drug delivery systems to control drug release in pharmaceutical dosage forms. Natural rubber latex (NRL) from Hevea brasiliensis consists of cis-1,4-polyisoprene as the major polymer. It presents interesting physical properties such as easy to manipulate, low cost, high mechanical resistance, and insoluble in water. The aim of this study was to use the NRL as binder in matrix tablets for controlling the release rate of drug. NRL, sodium carboxymethylcellulose, olive oil, Tween 80, and lactose were used as polymer, adsorbent, plasticizer, surfactant, and diluent, respectively. Propranolol hydrochloride was used as a model drug. Propranolol hydrochloride matrix tablets were prepared by conventional heat-melting method. The in vitro release of drug from matrix tablets was determined by UV-Vis method according to dissolution test under Propranolol Hydrochloride Tablets USP30-NF25 monograph. Morphology of propranolol hydrochloride matrix tablet before and after released study was observed by scanning electron microscopy (SEM). It was found that NRL matrix tablets could control the drug release up to 12 hours. The release profiles were best fitted with Higuchi model. NRL amounts affected the properties of the propranolol hydrochloride matrix tablets. Increasing the NRL quantity in the matrices provided the decrease of release rate of drug. SEM photographs showed the number, size, and distribution of pore in propranolol hydrochloride matrix tablets that depended on amount of NRL addition. These results confirmed that NRL was possible to use as binder for matrix tablets in oral drug delivery systems.

Rubber recovery from centrifuged natural rubber latex residue using sulfuric acid

Wirach Taweepreda

DOAJ (DOAJ: Directory of Open Access Journals) · 2013

Waste latex sludge from centrifuged residue, which is a null by-product of concentrated latex manufacturing, wasdigested to retrieve the rubber by using sulfuric acid. It was found that the acid concentration and digestion time have aneffect on the amount and purity of the retrieved rubber. Sulfuric acid at concentrations of more than 10% by weight with adigestion time of 48 hours completely digested waste latex sludge and gave rubber 10% by weight. The quality of the retrievedrubber was examined for Mooney viscosity (MV), plasticity retention index, nitrogen content, and ash content. The averagemolecular weight of the retrieved rubber, using gel permeation chromatography, was lower than that of normal natural rubber(NR) which corresponds with the MV and initial plasticity (Po). The molecular structure from Fourier transform infraredspectroscopy (FT-IR) indicated that the retrieved rubber surface is wet composed with hydroxyl functional ended group.The residue solution was evaporated and crystallized. The structure of crystals was determined using power X-ray diffractometer.

Efficacy of a Rubber Seated Cushion for Pressure Ulcer Prevention: An experimental Study /Wipa Sae-sia, Wirach Taweepreda and Luppana Kitrungrote

Wipa Sae‐Sia, Wirach Taweepreda, Luppana Kitrungrote

2013