Key Engineering Materials Vol. 914

Abstract: Naturally-occurring saturated fatty acids have been classified as the interesting biomaterials. Typically, the interfacial tension and wettability relying on intermolecular forces relate to the well-fitted performance with any target sites of in situ forming matrix. This research aimed to determine surface tension/contact angle of several saturated fatty acids in selected aprotic solvents commonly used in in situ forming system by varying fatty acid concentrations and molecular weights. Six fatty acids were dissolved in the aprotic solvents, namely 2-pyrrolidone (PYR), N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO). As fatty acid concentrations in binary mixtures increased, surface tension and contact angle became diminished except where DMSO was used as a solvent. The longer chain of fatty acid, the lower the surface tension except when C_14-16 fatty acid was dissolved in NMP. Contact angle was also decreased as the chain of fatty acid increased except for C_14-16 fatty acid-based preparation due to their viscosity. Understanding these fatty acid solution's surface tension/contact angle behaviors is useful for designing the suitable fatty acid-based in situ forming system.

Abstract: Progesterone (P4) is a neurosteroid hormone synthesized in both males and females, it is widely used in reproductive health and hormone replacement therapy. The aim of this study was to develop microemulsions (ME) and optimization of P4 microemulsion using a simplex lattice mixture design for enhancing the transdermal delivery of P4. Pseudo-ternary phase diagrams were generated to find the optimal ratio of the microemulsion constituents. The solubilities of P4 in different oils, surfactants, and co-surfactants were determined. The ME formulations of P4 were then prepared and optimized by simplex lattice mixture design. Each ME formulation was characterized for size, PDI, zeta potential, drug content, in vitro permeation study, and drug permeation in porcine skin. The result showed that the optimal ME formulation composed of 34.97 %w/w eugenol as the oil phase, 18.35 %w/w Labrasol^® as the surfactant, 36.69 %w/w ethanol as the cosurfactant, and 10.00% w/w water containing HPβCD (1.0 M). The optimized ME showed an appropriate size of about 178 ± 42 nm with a low polydispersity index (PDI) and almost neutral charge. The drug content of the optimized ME was about 19.9 ± 0.6 %w/w. The results of in vitro permeability showed that the optimized ME formulation was significantly higher than the drug suspension. Moreover, the P4 from the optimized ME was able to be deposited in the dermis (1.07 mg) at a higher extent than in the stratum corneum (0.65 mg). In conclusion, this study explored a formulation approach to improve the transdermal permeation of P4.

Abstract: Bacteria form biofilms to facilitate colonization, and biofilm formation on polymeric medical devices is a common cause of hospital-acquired infection. Simulated body fluid (SBF) is a supersaturated calcium-phosphate solution with ionic composition nearly equal to that of human blood plasma, and has been used to test the bioactivity of materials. The purpose of this work was to understand whether SBF influenced surface structure on bacterial adhesion and biofilm formation on polycarbonate, a polymer commonly used in medical devices. In this study, polycarbonate coupons were immersed in a SBF solution at 37 oC for 7 and 14 days and air-dried for 30 minutes, and compared with deionized water immersion. Colony biofilms of P. aeruginosa were then investigated by growing bacteria on top surface of immersed coupons for 24 and 48 hours, and observed by the quantitative assay (areal cell density) and visualized using a field emission scanning electron microscopy (FESEM). Results stated that a prolonged immersion time of coupons in deionized water enhanced biofilm growth. Immersion in SBF for a period of 14 days showed a significant reduction in the viability following 24 hours of incubation compared to that in deionized water incubated for 48 hours. FESEM further demonstrated that P. aeruginosa had a tendency to form biofilm on a polycarbonate substrate, and was able to develop biofilms on both the SBF and deionized water. Significant cell clusters and bacterial adhesion was observed at 48-hour incubation. These insights can potentially assist in the establishment of infection and colonization of this opportunistic pathogen, and will aid the development of strategies to prevent biofilm formation.

Abstract: Melasma, freckles, age spots, and acne scars are common aesthetic problems resulted from melanin overproduction. This study aimed to develop new skin depigmenting compounds and characterize on melanin inhibition activities. The fluorinated N-benzylaniline derivatives were synthesized and evaluated for their in vitro anti-tyrosinase activity. Derivatives with p-fluorine monosubstition, N-(4-fluorobenzyl)-3-fluoro-4-methoxyaniline (3d), was the most potent inhibitor against mushroom tyrosinase with 75.4 ± 0.34 % inhibition at 500 µM which was as potent as the positive control, kojic acid. Furthermore, compound 3d exhibited superior anti-melanogenic activity in α-MSH-induced B16F10 murine melanoma cells, compared to kojic acid. Therefore, N-(4-fluorobenzyl)-3-fluoro-4-methoxyaniline (3d) was proposed as a new agent effective against skin hyperpigmentation.

Abstract: Cinnamon bark oil (CO) has anticancer activity in various type of cancer cells and could be used alternatively to support anticancer drugs. For the enhancement of cytotoxic effects, the combination of bioactive compounds with chemotherapeutics drug has been interested in the possibility of cancer treatment. This study aimed to determine whether there is a synergistic effect between the combination of CO and chemotherapeutic drug such as imatinib mesylate (IM) on HCT 116 and HT29 colorectal cancer cell lines. The cytotoxic activities of CO and IM were investigated individually and their combination in each cancer cell line using cell viability assay. The interaction between CO and IM was determined using the combination index (CI) method. Cinnamon bark oil exhibited the high cytotoxicity on HCT116 cell, while IM showed the high cytotoxic activity on HT 29 cell. The tested combination decreased notably viability of cell and allowed to reduce the dose of imatinib chemotherapy drug. The combination of CO with IM showed a strong synergistic effect (CI < 1) on HT29 cell. For HCT116 cell treated combination of CO (4μg/mL) and IM (10μg/mL) demonstrated a strong synergistic effect (CI = 0.52). Thus, the combined CO and IM might be applied for pharmaceutical drug delivery for colon cancer treatment.

Abstract: Volatile oils are natural compounds that can be adopted in many drug and cosmetic formulations. Many volatile oils can be extracted from natural plants and they have their own special biological activities. Nine volatile oils including pine oil (P), guava leaf oil (G), lime peel oil (L), cinnamon bark oil (C), sage oil (S), tea tree oil (T) rosemary oil (R), clove oil (CL) and jasmine sambac oil (J) were in vitro tested for anti-microbial activities against various microbes and cytotoxicity properties agianst HCT116 and HT29 cell lines. From our result, for antimicrobial activities, the most effective oil against Gram positive such as Staphylococcus aureus are T, R and L. Only P showed the great inhibition on Gram negative bacteria such as Escherichia coli. C, P, L, T and R also exhibited different inhibitory effects on the pathogenic yeasts depending on the candida species. For the antitumoral activity on colorectal cancer cell lines, C showed the most cytotoxicity on both HCT116 and HT29 cells with IC50 value of 7.7 and 74.0 μg/ml, respectively. The second most cytotoxic was guava oil with the IC50 of 101.2 and 97.91 μg/ml on HCT116 and HT29, respectively. These investigated data may be useful as information for oil selection and development of pharmaceutical dosage forms using these natural volatile oils as the ingredients.

Abstract: Fruit, leaf, fruit stalk, and rhizome of Typha angustifolia, which is abundantly available in Thailand, were investigated for antimicrobial activities. The results showed that fruit ethanolic extract had high activity against Staphylococcus aureus and Bacillus subtilis similar to the fruit stalk and rhizome extracts whereas the lowest antibacterial activities was found in the leaf extract. Only rhizome extract had antifungal activity against Candida albicans. The fruit extract was chosen for furthur study because of its antibacterial action, ease of collecting, and preparation before usage. This fruit ethanolic extract was semi-purified by partition with petroleum ether, chloroform and ethylacetate, respectively and subsequently tested for antimicrobial activities by disc diffusion against S. aureus, Staphylococcus epidermidis, Sarcina lutea, Streptococcus faecalis, Streptococcus pneumoniae, Micrococcus flavus, Bacillus cereus, Bacillus pumillus, B. subtilis, Shigella somnei, Proteus mirabilis, Proteus valgalis, Alcaligenes fecalis, Serratia marcescens, Salmonella paratyphi A, Salmonella typhi, Escherechia coli, Pseudomonas aeruginosa, and Saccharomyces cerevisiae. The inhibitory zone against gram-positive bacteria was broader in all partitioned fractions than in gram-negative bacteria and yeast. Furthermore, none of the fractions were able to prevent the development of S. marcescens, P. aeruginosa, or E. coli. The inhibition zone of the ethyl acetate fraction was larger than that of chloroform and petroleum ether. In comparison to the other fractions, the chloroform fraction demonstrated the broadest inhibition zone against B. subtilis. Based on the bioautography investigation, it was reasonable to conclude that there were at least five antibacterial chemicals against B. subtilis. Therefore, fruit of T. angustifolia has the potential for use in the discovery of new antibacterial agents.

Abstract: Cancer is currently a major public health concern worldwide. Previous studies have shown that heat shock protein 90 (Hsp90) is the key common cause of cancer. Thus, Hsp90 is one of the important molecular targets for the development of Hsp90 cancer drug based on geldanamycin (GDM) and alvespimycin (17-DMAG). Herein, novel geldanamycin derivatives, S1-S6 were designed as potential Hsp90 cancer drug by targeting signal transduction pathway, especially against oncogenic client protein from Hsp90. The binding of S1-S6 in the cavity of Hsp90 were investigated by molecular docking using the iGEMDOCK v2.1 software. The results illustrated that S1-S6 bound in the binding site of Hsp90 with similar manner to GDM and 17-DMAG. The binding energies of S1-S6 in Hsp90 (PDB ID:1YET) (-137.49 to -123.24 kcal/mol) were comparable to that of GDM (-133.06 kcal/mol) while the binding energies of S1-S6 in Hsp90 (PDB ID:1OSF) (-137.49 to -131.22 kcal/mol) were slightly higher than that of 17-DMAG (-145.31 kcal/mol). S1-S6 interacted well by hydrogen bonding with key amino acids in the binding site of Hsp90, which could inhibit the cancer cell growth. Therefore, S1-S6 containing novel geldanamycin derivatives could be promising molecules for anti-cancer drug against Hsp90 2 types in the future.

Abstract: Tea infusion is one of the most widely popular beverages. With several medicinal activities, mulberry leaf is listed as a raw material for tea infusion by the Thai Ministry of Public Health. However, long-term consumption may lead to health risk from toxic trace elements accumulated in herbal raw materials. In this research, the potentially toxic metal (including As, Cd, Pb, Ni and Ba) contents were determined in six mulberry reference leaves and nineteen commercial tea infusion products from local harvester (LHG) and non-harvester (non-LHG) groups using ICP-MS. Each sample was analyzed in triplicate. Health risks of toxic metal consumption was evaluated through content mean value, t-test and Pearson correlation at the significance level of 0.05. The relevant aspects of principal component analysis were also discussed. No observed contents of heavy metals in all sample exceeded the limitation of Thai FDA and WHO. Yet, it was notified that quantity of As, Cd, Ni and Ba in commercial products was higher than that of references while there was no difference in Pb content between two groups. Further investigation found that Cd, Ni and Ba contents in samples from LHG were lower than those from non-LHG significantly. On the contrary, higher Pb content was found in sample from LHG than that from non-LHG group. The amount of As was not different in both groups. As the result, awareness of environmental controls in cultivation area and proper production is crucial to reduce health risk of exposure to heavy metals.

Abstract: A one-pot two-step microwave-assisted reaction was developed as key steps for the synthesis of 4-(hydroxy-(1H-1,2,3-triazol-4-yl))methyl phenol derivatives, 7a-g. The reaction steps involved in situ generations of azides, 5a-g which were further coupled with alkyne to undergo a cycloaddition reaction, under microwave heating at 70 °C, 15 min to generate 1,4 disubstituted 1,2,3-triazole compounds, 6a-g. These two reactions occurred in the same vial and so we call “one-pot two-step” synthesis. In such a method, the alkyl and arylalkyl azides were generated in a safe manner under microwave irradiation using polar aprotic solvent, dimethyl sulfoxide. In this study, it was demonstrated that the one-pot two-step reaction could avoid tedious extraction procedures and handling of potentially explosive azides, and provide good yields of products with much less period of reaction time compared with the conventional method.