Key Engineering Materials Vol. 859

Abstract: Clove oil is the volatile essential oil obtained from Syzygium aromaticum. Eugenol, which is the main component, has antimicrobial, antifungal activity and antioxidant. From antiseptic activity, clove oil can be used in treatment of oral cavity infection. The aims of this research are to formulate and evaluate clove oil mucoadhesive gel for oral applications. Gel bases were prepared from Poloxamer 407 (P407). The effect of clove oil, P407 and xanthan gum on formulations were studied. Clove oil preparations were evaluated for their physicochemical properties (physical appearance, pH, viscosity, gelling capacity and gel dissolving time at 37 °C in artificial saliva). Mucoadhesive property was studied using porcine buccal mucosa. The amount of eugenol in clove oil was analyzed by gas chromatography (GC). Stability study of clove oil gel was performed under stress and room temperature conditions (1 month). The results showed that preparations containing 0% and 1% clove oil were in situ gel while those containing 3% and 5% clove oil were gel. All formulations showed good and clear physical appearance with the pH value of 5.2. The gelling capacity and gel dissolving time of more than 15 minutes in artificial saliva at 37°C was found in all preparations. They also showed mucoadhesive property. The GC results showed that the amount of eugenol in clove oil were 99.52 ± 0.51 %V/V. The preparations containing 1% clove oil showed good physical and chemical stability after storage at room temperature for 1 month. There was no significant difference in the amount of eugenol after storage (p>0.05). In conclusion, the preparations containing 20% P407 and 1% clove oil are the most appropriate formulation.

Abstract: Clove oil, extracted from dried floral buds of clove (Syzygium aromaticum), are used in topical products because it has antioxidant and antimicrobial activities. Microemulsions (ME) are stable emulsion which can be formulated by simple mixing of oil, water, surfactant and co-surfactant. The objectives of this research were to develop and evaluate clove oil-loaded ME for topical application by using Tween 80 as surfactant. Ethanol, isopropanol and propylene glycol (PG) were used as co-surfactants. Pseudo ternary-phase diagram showed that using ethanol and isopropanol provided larger ME area than using PG in all surfactant:co-surfactant ratio (SR; 1:0.5, 1:1 and 1:2). Up to 20% w/w of clove oil can be loaded in ME by using surfactant mixture of 60-80% w/w. The effects of various amounts of clove oil (5-20%) and surfactant mixture (60, 70, 80%) at SR of 1:1 on physico-chemical properties of ME were observed. All formulations are transparent with the pH values of 6.8-8.0. The droplets size of ME using ethanol and isopropanol as co-surfactant ranged from 10-100 nm while that using PG was higher. Conductivity values showed that all formulations were o/w ME. Zeta potential values revealed stable particles. For ethanol and isopropanol, ME containing 5-10% clove oil and 60-70% SM showed good physico-chemical stability. The amount of eugenol in clove oil analyzed by gas chromatographic (GC-FID) method was 82.27% v/v. The stability test of selected formulations (70% surfactant mixture at SR = 1:1) was evaluated from %eugenol remaining at room temperature and in refrigerator after 4-week storage. It was found that the amount of eugenol in the formulation was effected by the storage condition. Our results indicate that clove oil can be prepared in ME with physico-chemical stability by using Tween 80 and ethanol as surfactant system.

Abstract: Xanthan gum (X)-incorporated natural rubber (NR) cast films were fabricated from blocked NR by solvent casting method using dichloromethane as the solvent. The rather smooth films were obtained. X markedly promoted both of water sorption and erosion in phosphate buffer pH 7.4 of these composite films. With increasing X amount also significantly enhanced the film tensile strength, Young’s modulus and area under the curve while did not affect contact angle of water/formamide and surface free energy. 30%X-loaded NR films exhibited the highest durability with apparently high water sorption and erosion for further using such as wound dressing.

Abstract: Borneol and dimethyl sulphoxide (DMSO) have been used as the skin penetration enhancers. Different concentrated borneol solutions in aprotic DMSO were prepared as the binary mixtures and determined their surface tension and contact angle behaviors using goniometer. Low borneol concentration minimized the surface tension and there was nearly stable contact angle for 30-70% borneol solutions. The trend contact angle value was decreased on glass slide, acrylic and LDPE whereas increasing on agarose gel and porcine tissues including buccal mucosa, gum and tongue with borneol concentration dependence. However, the borneol-DMSO binary mixture exhibited high wettability owing to its contact angle on glass surface was less than 90°. The solvent exchange between DMSO of borneol solutions and aqueous phase form agarose gel and porcine tissues including tongue, gum and buccal mucosa initiated the phase transformation from solution into matrix-like and promoted the higher contact angle with borneol concentration dependence. The understanding of surface tension and contact angle behaviors of aprotic borneol-DMSO binary mixture is useful for developing them into in situ forming gel for drug delivery such as in the oral cavity.

Abstract: The local drug delivery based on mucoadhesion is an effective medical treatment. The mucoadhesive property relies on the formulated gel having optimized rheology. The addition of the drug also showed a major influence towards the sol-gel transition. In this study, compositional effect of Eudragit E100^® base polymer, various mucoadhesive polymers, and the black ginger extract on the rheological property of the formulated sol-gel was assessed. It was found that gelling point and gel strength could be tuned mainly based on the concentration of Eudragit E100 limited at 40% w/w due to the viscosity. At Eudragit E100 of 30% w/w, 0.5% w/w herbal extract, and 1%w/w polyvinyl alcohol, the solution reached the gel point at 286 s (tan δ=1) with the gel strength of 1 kPa (G’=G”). For all the formulated sol-gels, the rheological property became better (faster gelling point with the gel strength varying from 100-700 kPa at low strain) a simulated saliva environment.

Abstract: Chitosan (CS) is known for excellent biodegradability and low immunogenicity. However, its low water solubility has hampered CS biomedical application. In this study, we aimed to modify CS with polyethylene glycol (PEG) to improve water solubility and explored the possibility to use as a drug delivery vehicle. Degree of substitution of PEG on CS was varied, ranged from 16% to 78%. After dispersing in water, CS-PEG₇₅₀ and CS-PEG₅₀₀₀ could spontaneously form small nanoaggreagtes (NGs) at low concentration, with critical aggregation concentration ranged from 32 μg/mL to 112 μg/mL. Upon encapsulation of curcumin, all NGs were slightly bigger in size. CS-PEG₇₅₀ (1:40) NGs showed the highest entrapment efficiency at 59%, while CS-PEG₅₀₀₀ (1:40) and (1:60) NGs exhibited 36.9% and 36.5% entrapment efficiency, respectively. With few steps of modification, this modified CS copolymers reveal improved water solubility and decent entrapment efficiency. Thus this copolymer is a potential contender as a drug delivery vehicle.

Abstract: Alstonia scholaris (L.) R. Br. (Apocynaceae) is a plant with various pharmacological activities, especially anti-inflammatory activity. There were rare reports about the phytochemicals of its flowers. This study aimed to determine the chemical constituents of the extracts from A. scholaris flowers along with screening for their anti-lipoxygenase activities. The fresh flowers (40 kg) of A. scholaris were dried at 45 ^◦C and powdered (4 kg, 10% yield of fresh flower). The powder of dry flowers (4 kg) were extracted with 95% ethanol by using ultrasonic assistance to obtain ethanolic crude extract (ASF-EtOH) 201 g (5% yield of dry flower). The ASF-EtOH (100 g) was further subjected to liquid-liquid partition to obtain dichloromethane layer (ASF-DCM), ethyl acetate layer (ASF-EtOAc) and water layer (ASF-Water) around 26.4 g (26.4% yield), 9.3 g (9.3% yield) and 46.6 g (46.6% yield), respectively. All of the extracts were quantified for their chemical compositions by using colorimetric methods. Then their anti-lipoxygenase activities were evaluated by using linoleic acid as a substrate and lipoxygenase as an enzyme. The results indicated that one gram of ASF-EtOH, ASF-DCM, ASF-EtOAc and ASF-Water contained total alkaloids, cardiac glycosides, flavonoids and triterpenoids in the range of 1.25-5.15 mg berberine chloride equivalent, 4.47-36.64 mg digoxin equivalent, 37.87-40.16 mg rutin equivalent and 110.88-359.32 mg ursolic acid equivalent, respectively. The inhibitory effects towards lipoxygenase enzyme of ASF-EtOH, ASF-DCM, ASF-EtOAc (0.2 mg/ml) were 73.7, 89.9 and 67.4 %, respectively, which were higher than that of diclofenac sodium, an anti-inflammatory drug, at the same concentration. While ASF-Water (1 mg/ml) inhibited lipoxygenase activity around 19.4%. These results exhibited potential of the flowers of A. scholaris to provide plenty of secondary metabolites with potent anti-lipoxygenase activity. Therefore, the flowers of A. scholaris is a good material for further purification and discovery of anti-lipoxygenase agent.

Abstract: The aim of this study was to investigate the synergistic antioxidant activity of microemulsion containing mixed Moringa oleifera seed oil and Perilla frutescens seed oils, compared with microemulsion of single oils. The novel microemulsions for the moringa, perilla, and mixed seed oils were formulated by mixing appropriate amount of surfactant, water, and oil phase. The formulation containing the maximum amount of oil which appeared transparent was further evaluated for particle size, size distribution, surface charge, pH, and rheological behavior. The in vitro antioxidant properties of microemulsions were investigated in comparison with essential oils. Cream containing microemulsion was prepared and its physical stability was investigated by heating-cooling cycles. The results showed that the maximum content of oil incorporated in microemulsion system was 12.5%. The mean droplet sizes of moringa, perilla, and mixed oil microemulsion were 159.33±0.77, 183.86±1.42, and 263.43± 9.40 nm, respectively. All formulations exhibited pseudoplastic flow behavior. The mixture of moringa and perila seed oils in microemulsion possessed the highest significant antioxidant effect against 1,1-diphenyl-2-picrylhydrazyl compared with single oil microemulsion. The cream containing microemulsion exhibited good physical stability. Thus, the current research reveals the benefits of microemulsion containing mixed moringa and perilla seed oils based cream compared with single essential oils.

Abstract: Phase inversion in situ forming matrix is one of the promising drug delivery systems for periodontitis treatment owing to the prospective high antimicrobial agent level in the gingival crevicular fluid. Typically, this drug delivery system is a fluid polymeric solution that could change simultaneously to matrix-like after injection into aqueous physiological environment. The main propose of the current study was to achieve successful development of antibacterial agent-incorporated cholesterol phase inversion in situ forming matrix for crevicular pocket delivery. In this study, cholesterol was used as a fat matrix former, while N-methyl pyrrolidone (NMP) was used as the solvent and menthol was used as co-solvent. The 10%w/w metronidazole or doxycycline hyclate was employed as the active compounds. The developed formula were evaluated for viscosity and rheological behavior, antimicrobial activity using cup agar diffusion method and in vitro drug release using dialysis tube method. The consistency index from rheological test of doxycycline hyclate and metronidazole-loaded in situ forming matrices was not significantly different (p<0.05). Interestingly, the viscosity of all formula was quite low; thus, this characteristic provoked an ease of injection. They inhibited against Porphyromonas gingivalis efficiently more than cholesterol in situ forming matrix base (p<0.05). Drug release from systems loaded with doxycycline hyclate and metronidazole were rapid and nearly not different. Owing to the apparent efficiently inhibition against Porphyromonas gingivalis the in situ forming matrix loading doxycline hyclate was selected for further development to minimize the burst release and to prolong the drug release.

Abstract: Chitosan (CS) is a biodegradable and highly positive charged polymer that can be utilized as a non-viral vector for gene delivery. However, its transfection efficiency is low. Spermidine (SPD) and spermine (SPM) are ordinary polyamines found in almost all living organisms. Their structures contain tri- and tetra-amine, respectively. The present study aims to elucidate the effect of SPD or SPM on transfection efficiency and cytotoxicity of CS/DNA complexes in human cervical carcinoma (HeLa) cells. The ternary complexes (CS, DNA and SPD or SPM) at different weight ratios and mixing orders were formulated and tested on transfection efficiency. Their particle sizes and charges were also estimated. CS that has a molecular weight of 45,000 Daltons and degree of deacetylation of 85 was able to form complete complex with plasmid DNA expressing enhanced green fluorescence protein (pEGFP-C2) at weight ratio of 4. The SPM/CS/DNA (1:4:1) and SPD/ CS/DNA (512:4:1) complexes illustrated the greatest transfection efficiency. Moreover, the transfection efficiency was affected by the mixing order between CS, DNA and SPD or SPM. For cell toxicity experiments, more than 85% the average cell survival of the complexes were detected by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) cell growth assay. These findings suggest that addition of either SPD or SPM to CS before forming ternary complexes with DNA may significantly improve gene delivery potential in vitro.