Sakchai Wittaya-areekul

Development and in vitro evaluation of chitosan-Eudragit RS 30D composite wound dressings

The purpose of this research was to design and evaluate chitosan-based films intended for wound dressing application. Required properties for successful wound dressing, such as liquid uptake, vapor and oxygen penetration, bioadhesiveness, and film elasticity, were examined. Water uptake and vapor penetration of the films were determined gravimetrically, while oxygen penetration was determined by Winkler’s method. The bioadhesive properties were determined with an in-house pulley system instrument using a pig gut model. Film elasticity was determined with a stretch test using an Instron apparatus. The results showed that pure chitosan films exhibited relatively high liquid uptake and the adsorption tended to decrease with the addition of Eudragit RS 30D. Moisture vapor and oxygen were found to be able to penetrate through all film formulations in comparable amounts. The bioadhesiveness test tended to show lower bioadhesive properties with the addition of Eudragit RS 30D. The formulation containing only chitosan exhibited low elongation of the film at 2 N, but the film elasticity increased with the addition of Eudragit RS 30D. In conclusion, the addition of Eudragit RS 30D could improve a film’s mechanical properties but lower its bioadhesiveness.

Stability studies of saponins in Bacopa monnieri dried ethanolic extracts.

Bacopa monnieri (L.) Wettst. (Brahmi) is currently used as a drug and food supplement for memory improvement. However, studies on the physical and chemical stability of the extract components, especially on the lead compound important for pre-formulation, have not yet been reported. In this study, the stabilities of the crude extract and the diluted crude extract were investigated at various temperatures using saponin glycosides, bacopaside I and bacoside A3 as markers for quantitative analysis. The stability testing of bacopaside I and bacoside A3 standard solution was performed at various temperatures and pH values. The quantity of both compounds under all conditions was analyzed using HPLC techniques. The moisture adsorption of the crude extract was determined at 5, 40, 60 and 80 degrees C at 75 % relative humidity using gravimetric methods. The results revealed that the crude extract quickly adsorbed moisture up to 54 % w/w at both 40 and 80 degrees C, while it only slowly adsorbed moisture at 5 degrees C. The amounts of intact bacopaside I and bacoside A3 in the crude extract decreased drastically at 80 degrees C, slowly at 40 and 60 degrees C, and remained unchanged at 5 degrees C during the period of investigation. Moreover, the amount of both compounds in the standard solution dropped sharply at a pH of 1.2 but slowly at pH 6.8 and 9.0, respectively. The pre-formulation data could be further used for improvement of the final product quality.

Mangifera indica Fruit Extract Improves Memory Impairment, Cholinergic Dysfunction, and Oxidative Stress Damage in Animal Model of Mild Cognitive Impairment

To date, the effective preventive paradigm against mild cognitive impairment (MCI) is required. Therefore, we aimed to determine whether Mangifera indica fruit extract, a substance possessing antioxidant and cognitive enhancing effects, could improve memory impairment, cholinergic dysfunction, and oxidative stress damage in animal model of mild cognitive impairment. Male Wistar rats, weighing 180–200 g, were orally given the extract at doses of 12.5, 50, and 200 mg·kg−1 BW for 2 weeks before and 1 week after the bilateral injection of AF64A (icv). At the end of study, spatial memory, cholinergic neurons density, MDA level, and the activities of SOD, CAT, and GSH-Px enzymes in hippocampus were determined. The results showed that all doses of extract could improve memory together with the decreased MDA level and the increased SOD and GSH-Px enzymes activities. The increased cholinergic neurons density in CA1 and CA3 of hippocampus was also observed in rats treated with the extract at doses of 50 and 200 mg·kg−1 BW. Therefore, our results suggested that M. indica, the potential protective agent against MCI, increased cholinergic function and the decreased oxidative stress which in turn enhanced memory. However, further researches are essential to elucidate the possible active ingredients and detail mechanism.

Film coating of seeds with Bacillus cereus RS87 spores for early plant growth enhancement

The plant growth-promoting rhizobacterium Bacillus cereus RS87 was previously reported to promote plant growth in various crops in both greenhouse and field trials. To apply as a plant growth promoting agent with practical use, it is essential to ease the burden of routine preparation of a fresh suspension of strain RS87 in laboratory. The objectives of this study were to investigate the feasibility of film-coating seeds with B. cereus RS87 spores for early plant growth enhancement and to reveal the indoleacetic acid (IAA) production released from strain RS87. The experiment consisted of the following 5 treatments: nontreated seeds, water-soaked seeds, film-coated seeds, seeds soaked with vegetative cells of strain RS87, and film-coated seeds with strain RS87 spores. Three experiments were conducted separately to assess seed emergence, root length, and plant height. Results showed that both vegetative cells and spores of strain RS87 significantly promoted (P < or = 0.05) seed emergence, root length and plant height over the control treatments. The strain RS87 also produced IAA. In conclusion, the film coating of seeds with spores of B. cereus RS87 demonstrated early plant growth enhancement as well as seeds using their vegetative cells. IAA released from strain RS87 would be one of the mechanisms for plant growth enhancement.

In vivo chondrocyte and transforming growth factor-β1 delivery using the thermosensitive chitosan/starch/β-glycerol phosphate hydrogel

In present study, the chitosan/starch/β-glycerol phosphate hydrogel was investigated as an effective carrier for chondrocytes and delivery of transforming growth factor-β1. In vitro study indicated that transforming growth factor-β1 was released sustainably for 14 days with its biological activity to stimulate chondrocyte functions, as indicated by the strong expression of type II collagen protein. Subcutaneous implantation to rats revealed the strong expressions of type II collagen and aggrecan messenger ribonucleic acids, and also type II collagen protein was observed in the hydrogel in combination with transforming growth factor-β1 within 2 weeks. Our collective results showed the potential of chitosan/starch/β-glycerol phosphate hydrogel for effective delivery of chondrocytes and transforming growth factor-β1, and preserve chondrocytes’ phenotype and functions in vitro.

A thermosensitive chitosan/corn starch/β-glycerol phosphate hydrogel containing TGF-β1 promotes differentiation of MSCs into chondrocyte-like cells

Our previous study showed that thermosensitive chitosan/corn starch/β-glycerol phosphate (C/S/β-GP) hydrogel was an effective carrier for chondrocytes and their transforming factor, TGF-β1. In the present study, MSCs were grown in C/S/β-GP hydrogels as an effective tool for chondrocyte-like cell differentiation. The MSCs-encapsulated hydrogel was prepared by blending chitosan solution (1.70% w/v in 0.1 M HCl) with pregelatinized corn starch solution (1.70% w/v). The total final concentration of the blended polymers was 1.53% w/v, and the weight ratio of chitosan to corn starch was 4 to 1. The TGF-β1 (final concentration of 25 ng/mL) and 5 × 105 MSCs were added to 500 μL chitosan/starch solution. Finally, β-GP (60% w/v) was added to obtain 6.0% w/v final concentration. The C/S/β-GP hydrogel changed from a liquid at room temperature to a gel at 37 ± 2°C. It converted the fibroblast-like MSCs into spheroid cells. In hydrogels containing TGF-β1, these cells further differentiated into chondrocyte-like cells. This was shown by their expressions of type II collagen and aggrecan mRNA. Type I collagen mRNA was initially expressed but this disappeared by 6 weeks in culture suggesting a complete chondrocyte differentiation by that time. Type II collagen protein production was detected by immunohistochemistry and immunofluorescence, and successively increased after 4–6 weeks in culture. Neither the mRNA nor the collagen expression could be detected in the absence of TGF-β1. The data indicate that MSCs would be an appropriate chondrocyte precursor in conjunction with our hydrogel loading TGF-β1 which is able to sustain chondrocyte function.

Brahmi, a Medicinal Plant for Memory Improvement

Faculty of Pharmaceutical Sciences and Center of Excellence for Innovation in Chemistry, Naresuan University, Phitsanulok 65000, Thailand; Department of Physiology, Faculty of Medical Sciences, Naresuan University, Phitsanulok 65000, Thailand; Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; Department of Preclinical Science, Faculty of Medicine, Thammasat University, Pathumthani. 12120, Thailand; Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand; Department of Pharmacognosy and Pharmaceutical Chemistry, Faculty of Pharmacy, Srinakharinwiroj University, 26120 Nakhonayok, Thailand; Department of Medicinal Plant Breeding, Graduate School of Pharmaceutical Sciences, Kyushu University.Fukuoka 812-8582, Japan; E-mail: k_ingkaninan@yahoo.com