Rhodomyrtus tomentosa (Aiton) Hassk. has been widely exploited in traditional medicine for the tr... more Rhodomyrtus tomentosa (Aiton) Hassk. has been widely exploited in traditional medicine for the treatment of many diseases and disorders. There have been no scientific reports on safety information of R. tomentosa leaf extract. The present study attempted to assess in vivo toxicity profile of R. tomentosa extract in order to provide information on the safety margin of the extract to support its pharmacological and medical applications. The extract at a dosage of 0.5 to 3.0 g/kg body weight of mice was orally administered daily up to 14 days. Behavioural and functional integrity were assessed by functional observational battery (FOB) analysis. Histopathological and ultrastructural changes were visualized under light microscopy and transmission electron microscopy, respectively. The extract at the concentration up to 3.0 g/kg body weight per day for 14 days caused no mortality. The extract at 0.5 to 2.0 g/kg body weight showed no adverse effects or signs of toxicity. It is evident that...
Bionanotechnology has increasingly gained attention in biomedical fields as antifungal and antibi... more Bionanotechnology has increasingly gained attention in biomedical fields as antifungal and antibiofilm agents. In this study, biosynthesized silver nanoparticles (bio‐AgNPs) using aqueous Eucalyptus camaldulensis leaf extract were successfully performed by a one‐step green approach. Spherical‐shaped nanoparticles, approximately 8.65 nm, exhibited noncytotoxicity to erythrocytes, HeLa, and HaCaT cells. The synthesized nanoparticles showed strong fungicidal activity ranging from 0.5 to 1 µg/ml. The nanoparticles affected Candida adhesion and invasion into host cells by reduced germ tube formation and hydrolytic enzyme secretion. Inhibitory effects of bio‐AgNPs on Candida biofilms were evaluated by the prevention of yeast‐to‐hyphal transition. A decrease in cell viability within mature biofilm demonstrated the ability of bio‐AgNPs to penetrate into the extracellular matrix and destroy yeast cell morphology, leading to cell death. Molecular biology study on biofilms confirmed downregulation in the expression of genes ALS3, HWP1, ECE1, EFG1, TEC1, ZAP1, encoding hyphal growth and biofilm development and PLB2, LIP9, SAP4, involved in hydrolytic enzymes. In addition to candida treatment, the bio‐AgNPs could be applied as an antioxidant to protect against oxidative stress‐related human diseases. The findings concluded that bio‐AgNPs could be used as an antifungal agent for candida treatment, as well as be incorporated in medical devices to prevent biofilm formation.
Infections due to carbapenem-resistant Escherichia coli (CREC) are problematic due to limitation ... more Infections due to carbapenem-resistant Escherichia coli (CREC) are problematic due to limitation in treatment options. Combination therapies of existing antimicrobial agents have become a reliable strategy to control these infections. In this study, the synergistic effects of meropenem in combination with aminoglycosides were assessed by checkerboard and time-kill assays. Of the 35 isolates, 19 isolates (54.3%) were resistant to carbapenems (imipenem and meropenem) with the MIC ranges from 16 to 128 µg/mL. These isolates were resistant to almost all antibiotic classes. Molecular characteristics revealed co-harboring of carbapenemase (blaNDM-1, blaNDM-5 and blaOXA-48) and extended-spectrum β-lactamases (ESBL) genes (blaCTX-M, blaSHV and blaTEM). The checkerboard assay displayed synergistic effects of meropenem and several aminoglycosides against most CREC isolates. Time-kill assays further demonstrated strong synergistic effects of meropenem in combination with either amikacin, genta...
Rhodomyrtone, a plant-derived principal compound isolated from Rhodomyrtus tomentosa (Myrtaceae) ... more Rhodomyrtone, a plant-derived principal compound isolated from Rhodomyrtus tomentosa (Myrtaceae) leaf extract, was assessed as a potential natural alternative for the treatment of acne vulgaris. The clinical efficacy of a 1% liposomal encapsulated rhodomyrtone serum was compared with a marketed 1% clindamycin gel. In a randomized and double-blind controlled clinical trial, 60 volunteers with mild to moderate acne severity were assigned to two groups: rhodomyrtone serum and clindamycin gel. The volunteers were instructed to apply the samples to acne lesions on their faces twice daily. A significant reduction in the total numbers of acne lesions was demonstrated in both treatment groups between week 2 and 8 (p < 0.05). Significant differences in acne numbers compared with the baseline were evidenced at week 2 onwards (p < 0.05). At the end of the clinical trial, the total inflamed acne counts in the 1% rhodomyrtone serum group were significantly reduced by 36.36%, comparable to ...
Failure in the prevention of cross-transmission from contaminated gloves has been recognized as a... more Failure in the prevention of cross-transmission from contaminated gloves has been recognized as an important factor that contributes to the spread of several healthcare-associated infections. Ex situ coating process with silver nanoparticles (AgNPs) using Eucalyptus citriodora ethanolic leaf extract as reducing and capping agents to coat glove surfaces has been developed to prevent this mode of transmission. Elemental analysis of coated gloves showed 24.8 Wt% silver densely adhere on the glove surface. The coated gloves fully eradicated important hospital-acquired pathogens including Gram-positive bacteria, Gram-negative bacteria, and yeasts within 1 h. The coated gloves showed significant reduction, an average of 5 logs when tested against all standard strains and most clinical isolates (p < 0.01). Following prolonged exposure, the coating significantly reduced the numbers of most adhered pathogenic species, compared with uncoated gloves (p < 0.0001), which was observed by fl...
The spread of multi-drug resistant (MDR) pathogens and the lagging pace in the development of nov... more The spread of multi-drug resistant (MDR) pathogens and the lagging pace in the development of novel chemotherapeutic agents warrant the use of combination therapy as a reliable, cost-effective interim option. In this study, the synergistic effects of fosfomycin in combination with other antibiotics were assessed. Of the 193 isolates, 90.6% were non-susceptible to fosfomycin, with minimum inhibitory concentrations (MICs) of ≥128 µg/mL. Antibacterial evaluation of fosfomycin-resistant isolates indicated multi-drug resistance to various antibiotic classes. Combinations of fosfomycin with 12 commonly used antibiotics synergistically inhibited most fosfomycin-resistant isolates. The fractional inhibitory concentration index indicated that combining fosfomycin with either aminoglycosides, glycylcyclines, fluoroquinolones, or colistin resulted in 2- to 16-fold reduction in the MIC of fosfomycin. Time-kill kinetics further confirmed the synergistic bactericidal effects of fosfomycin in comb...
Pathogen resistance to conventional antibiotics has become a serious clinical and public health p... more Pathogen resistance to conventional antibiotics has become a serious clinical and public health problem, making the development of an alternative mean a very urgent issue. Recently, biosynthesis of silver nanoparticles (AgNPs) was successfully accomplished in the presence of Eucalyptus citriodora leaf extract as a reducing agent. In this study, the antimicrobial mechanisms of AgNPs against important hospital‐acquired pathogens, including Gram‐positive, Gram‐negative bacteria, and fungi were further assessed. The results indicated that AgNPs could enhance a broad antimicrobial spectrum against drug‐resistant organisms, with a range of minimum inhibitory concentration from 0.02 to 0.36 μg/mL. Time‐kill assay showed that AgNPs produced bactericidal effects on the microorganisms. AgNPs could significantly reduce biofilm production in pathogens without affecting growth of the pathogens (p < 0.05). AgNPs inhibited cell viability and biofilm formation in a dose‐dependent manner. Cell membrane damage in microorganisms resulting from effects of AgNPs was observed. A significant increase in per cent uptake of crystal violet was observed in all isolates treated with AgNPs when compared with the control (p < 0.05). Upon treatment with AgNPs, the surface charge of the reference strains and clinical isolates of pathogens moved towards neutral. The alteration of surface potential after exposure to AgNPs could contribute to membrane disruption and cell viability. Scanning electron microscopy further confirmed morphological cell changes and disrupted the cell membrane. Increasing resistance to AgNPs was not induced by stepwise isolation of the bacteria after 45 passages on Luria‐Bertani agar supplemented with AgNPs. Furthermore, AgNPs was not toxic to red blood cells.
Eleutherine americana, a well‐known Asian medicinal herb, has been claimed for many biological ac... more Eleutherine americana, a well‐known Asian medicinal herb, has been claimed for many biological activities. In this study, potential of E. americana ethanolic extract against adhesion and invasion of Caco‐2 cells by commonly contaminated Campylobacter spp. was evaluated. MIC₅₀ values of E. americana extract against 39 enteritis patient and 26 chicken isolates were 125 µg/ml. Two models were set up: Model I, Prevention: Preincubation of E. americana extract with campylobacters before adding to Caco‐2 cells. Adhesion to and invasion of Caco‐2 cells by campylobacters were completely inhibited within 12 hr. Model II, Treatment: Preincubation of the organisms with Caco‐2 cells before adding the extract. Adding the extract after the bacteria were mixed with Caco‐2 cells resulted in moderate effect on adhesion, but complete prevention of penetration of the organisms into Caco‐2 cells was observed. The extract at the highest concentration tested (250 μg/ml) demonstrated no cytotoxicity toward Caco‐2 cells. PRACTICAL APPLICATIONS: Eleutherine americana bulb extract could be applied as an effective food preservative to control campylobacter contamination at initial stage in food chain. In addition, the extract provides a curative approach to campylobacter infections.
Endotracheal tubes (ETTs) are a common source of bacterial colonization, leading to ventilator-as... more Endotracheal tubes (ETTs) are a common source of bacterial colonization, leading to ventilator-associated pneumonia (VAP). This research developed a biofilm-resistant ETT, following the principles of green chemistry. Using an aqueous layer-by-layer (LbL) technique, a thick polyelectrolyte multilayered film was deposited on a ventilation tube. The polyelectrolyte multilayered film accommodated silver nanoparticles (AgNPs) formed in situ by reducing Ag+ ions with Eucalyptus citriodora leaf extract. The multilayered film coating conformed to the curved surfaces of the ETT. Film thickness and silver content increased exponentially with the number of polyelectrolyte bilayer pairs, and a sufficiently high AgNPs content of 10-30%w/w was obtained at 75 to 125 bilayer films. Adhesion of the Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa was prevented by 99.9 and 99.99%, respectively, without cytotoxic effects against human lung epithelial cells (p < 0.05).
Psoriasis is a common skin disease pathogenically driven by TNF and IL-17A-induced epidermal hype... more Psoriasis is a common skin disease pathogenically driven by TNF and IL-17A-induced epidermal hyperproliferation and inflammatory responses. The ongoing need for new therapeutic agents for psoriasis has highlighted medicinal plants as sources of phytochemicals useful for treating psoriatic disease. Rhodomyrtone, a bioactive phytochemical from Rhodomyrtus tomentosa, has well-established anti-proliferative activities. This study assessed the potential of rhodomyrtone for curtailing TNF/IL-17A-driven inflammation. Stimulating human skin organ cultures with TNF+IL-17A to model the skin inflammation in psoriasis, we found that rhodomyrtone significantly decreased inflammatory gene expression and the expression and secretion of inflammatory proteins, assessed by qRT-PCR, immunohistochemistry and ELISA assays respectively. RNA-seq analysis of monolayer primary keratinocytes treated with IL-17A/TNF showed that rhodomyrtone inhibited 724/1587 transcripts >2-fold altered by IL-17A/TNF (p<...
The capacity to resist the bactericidal action of complement (C′) is a strong but poorly understo... more The capacity to resist the bactericidal action of complement (C′) is a strong but poorly understood virulence trait in Klebsiella spp. Killing requires activation of one or more C′ pathways, assembly of C5b-9 membrane attack complexes (MACs) on the surface of the outer membrane (OM), and penetration of MACs into the target bilayer. We interrogated whole-genome sequences of 164 Klebsiella isolates from three tertiary hospitals in Thailand for genes encoding surface-located macromolecules considered to play a role in determination of C′ resistance. Most isolates (154/164) were identified as Klebsiella pneumoniae, and the collection conformed to previously established population structures and antibiotic resistance patterns. The distribution of sequence types (STs) and capsular (K) types were also typical of global populations. The majority (64%) of isolates were resistant to C′, and the remainder were either rapidly or slowly killed. All isolates carried genes encoding capsular polysa...
Particularly in Asia medicinal plants with antimicrobial activity are used for therapeutic purpos... more Particularly in Asia medicinal plants with antimicrobial activity are used for therapeutic purpose. One such plant-derived antibiotic is rhodomyrtone (Rom) isolated from Rhodomyrtus tomentosa leaves. Rom shows high antibacterial activity against a wide range of Gram-positive bacteria, however, its mode of action is still unclear. Reporter gene assays and proteomic profiling experiments in Bacillus subtilis indicate that Rom does not address classical antibiotic targets like translation, transcription or DNA replication, but acts at the cytoplasmic membrane. In Staphylococcus aureus, Rom decreases the membrane potential within seconds and at low doses, causes release of ATP and even the excretion of cytoplasmic proteins (ECP), but does not induce pore-formation as for example nisin. Lipid staining revealed that Rom induces local membrane damage. Rom's antimicrobial activity can be antagonized in the presence of a very narrow spectrum of saturated fatty acids (C15:0, C16:0, or C18...
To determine the anti-Streptococcus mutans mechanisms of action of lupinifolin from Albizia myrio... more To determine the anti-Streptococcus mutans mechanisms of action of lupinifolin from Albizia myriophylla Benth. (Fabaceae) wood and provide scientific evidence to support the traditional use of the plant against dental caries. The minimum inhibitory concentration (MIC) was evaluated using the broth micro-dilution method. The effects of lupinifolin on bactericidal activity, bacterial cell walls, and membranes were investigated by time-kill, lysis, and leakage assays, respectively. Electron microscopy was utilized to observe any cell morphological changes caused by the compound. Localization of lupinifolin in S. mutans was detected using the thin layer chromatography technique. The MIC range of lupinifolin against S. mutans (n=6) was 2-4 μg/ml. This compound displayed bactericidal effects on S. mutans ATCC 25175 by 90-99.9% killing at 4MIC-16MIC after 8-24 hours. Lupinifolin-treated cells demonstrated no lysis. However, significant cytoplasmic leakage through the bacterial membrane was...
Background Quercus infectoria G. Olivier (Fagaceae) nutgalls have been widely employed in traditi... more Background Quercus infectoria G. Olivier (Fagaceae) nutgalls have been widely employed in traditional Asian medicine for several treatments, especially wounds and skin disorders. However, the effects of this plant on wound healing have not yet been clearly elucidated. This present work was focused on utilization of Quercus infectoria (Qi) as a topical agent for chronic wound treatment. Methods Twenty Qi formulations (QiFs) were pharmaceutically formulated and antibacterial activity of all formulations was performed. The best formulation based on an antibacterial activity was selected for evaluation of wound healing property. Total phenolics, total flavonoids, and an anti-oxidant activity of the selected formulation were also investigated. Wound healing activity was assessed in streptozotocin-induced diabetic rats and control rats. Streptozotocin injection (50 mg/kg) was found to induce marked hyperglycaemia, compared with citrate-injected controls. Two wounds were created on the upp...
Rhodomyrtus tomentosa (Aiton) Hassk. has been widely exploited in traditional medicine for the tr... more Rhodomyrtus tomentosa (Aiton) Hassk. has been widely exploited in traditional medicine for the treatment of many diseases and disorders. There have been no scientific reports on safety information of R. tomentosa leaf extract. The present study attempted to assess in vivo toxicity profile of R. tomentosa extract in order to provide information on the safety margin of the extract to support its pharmacological and medical applications. The extract at a dosage of 0.5 to 3.0 g/kg body weight of mice was orally administered daily up to 14 days. Behavioural and functional integrity were assessed by functional observational battery (FOB) analysis. Histopathological and ultrastructural changes were visualized under light microscopy and transmission electron microscopy, respectively. The extract at the concentration up to 3.0 g/kg body weight per day for 14 days caused no mortality. The extract at 0.5 to 2.0 g/kg body weight showed no adverse effects or signs of toxicity. It is evident that...
Bionanotechnology has increasingly gained attention in biomedical fields as antifungal and antibi... more Bionanotechnology has increasingly gained attention in biomedical fields as antifungal and antibiofilm agents. In this study, biosynthesized silver nanoparticles (bio‐AgNPs) using aqueous Eucalyptus camaldulensis leaf extract were successfully performed by a one‐step green approach. Spherical‐shaped nanoparticles, approximately 8.65 nm, exhibited noncytotoxicity to erythrocytes, HeLa, and HaCaT cells. The synthesized nanoparticles showed strong fungicidal activity ranging from 0.5 to 1 µg/ml. The nanoparticles affected Candida adhesion and invasion into host cells by reduced germ tube formation and hydrolytic enzyme secretion. Inhibitory effects of bio‐AgNPs on Candida biofilms were evaluated by the prevention of yeast‐to‐hyphal transition. A decrease in cell viability within mature biofilm demonstrated the ability of bio‐AgNPs to penetrate into the extracellular matrix and destroy yeast cell morphology, leading to cell death. Molecular biology study on biofilms confirmed downregulation in the expression of genes ALS3, HWP1, ECE1, EFG1, TEC1, ZAP1, encoding hyphal growth and biofilm development and PLB2, LIP9, SAP4, involved in hydrolytic enzymes. In addition to candida treatment, the bio‐AgNPs could be applied as an antioxidant to protect against oxidative stress‐related human diseases. The findings concluded that bio‐AgNPs could be used as an antifungal agent for candida treatment, as well as be incorporated in medical devices to prevent biofilm formation.
Infections due to carbapenem-resistant Escherichia coli (CREC) are problematic due to limitation ... more Infections due to carbapenem-resistant Escherichia coli (CREC) are problematic due to limitation in treatment options. Combination therapies of existing antimicrobial agents have become a reliable strategy to control these infections. In this study, the synergistic effects of meropenem in combination with aminoglycosides were assessed by checkerboard and time-kill assays. Of the 35 isolates, 19 isolates (54.3%) were resistant to carbapenems (imipenem and meropenem) with the MIC ranges from 16 to 128 µg/mL. These isolates were resistant to almost all antibiotic classes. Molecular characteristics revealed co-harboring of carbapenemase (blaNDM-1, blaNDM-5 and blaOXA-48) and extended-spectrum β-lactamases (ESBL) genes (blaCTX-M, blaSHV and blaTEM). The checkerboard assay displayed synergistic effects of meropenem and several aminoglycosides against most CREC isolates. Time-kill assays further demonstrated strong synergistic effects of meropenem in combination with either amikacin, genta...
Rhodomyrtone, a plant-derived principal compound isolated from Rhodomyrtus tomentosa (Myrtaceae) ... more Rhodomyrtone, a plant-derived principal compound isolated from Rhodomyrtus tomentosa (Myrtaceae) leaf extract, was assessed as a potential natural alternative for the treatment of acne vulgaris. The clinical efficacy of a 1% liposomal encapsulated rhodomyrtone serum was compared with a marketed 1% clindamycin gel. In a randomized and double-blind controlled clinical trial, 60 volunteers with mild to moderate acne severity were assigned to two groups: rhodomyrtone serum and clindamycin gel. The volunteers were instructed to apply the samples to acne lesions on their faces twice daily. A significant reduction in the total numbers of acne lesions was demonstrated in both treatment groups between week 2 and 8 (p < 0.05). Significant differences in acne numbers compared with the baseline were evidenced at week 2 onwards (p < 0.05). At the end of the clinical trial, the total inflamed acne counts in the 1% rhodomyrtone serum group were significantly reduced by 36.36%, comparable to ...
Failure in the prevention of cross-transmission from contaminated gloves has been recognized as a... more Failure in the prevention of cross-transmission from contaminated gloves has been recognized as an important factor that contributes to the spread of several healthcare-associated infections. Ex situ coating process with silver nanoparticles (AgNPs) using Eucalyptus citriodora ethanolic leaf extract as reducing and capping agents to coat glove surfaces has been developed to prevent this mode of transmission. Elemental analysis of coated gloves showed 24.8 Wt% silver densely adhere on the glove surface. The coated gloves fully eradicated important hospital-acquired pathogens including Gram-positive bacteria, Gram-negative bacteria, and yeasts within 1 h. The coated gloves showed significant reduction, an average of 5 logs when tested against all standard strains and most clinical isolates (p < 0.01). Following prolonged exposure, the coating significantly reduced the numbers of most adhered pathogenic species, compared with uncoated gloves (p < 0.0001), which was observed by fl...
The spread of multi-drug resistant (MDR) pathogens and the lagging pace in the development of nov... more The spread of multi-drug resistant (MDR) pathogens and the lagging pace in the development of novel chemotherapeutic agents warrant the use of combination therapy as a reliable, cost-effective interim option. In this study, the synergistic effects of fosfomycin in combination with other antibiotics were assessed. Of the 193 isolates, 90.6% were non-susceptible to fosfomycin, with minimum inhibitory concentrations (MICs) of ≥128 µg/mL. Antibacterial evaluation of fosfomycin-resistant isolates indicated multi-drug resistance to various antibiotic classes. Combinations of fosfomycin with 12 commonly used antibiotics synergistically inhibited most fosfomycin-resistant isolates. The fractional inhibitory concentration index indicated that combining fosfomycin with either aminoglycosides, glycylcyclines, fluoroquinolones, or colistin resulted in 2- to 16-fold reduction in the MIC of fosfomycin. Time-kill kinetics further confirmed the synergistic bactericidal effects of fosfomycin in comb...
Pathogen resistance to conventional antibiotics has become a serious clinical and public health p... more Pathogen resistance to conventional antibiotics has become a serious clinical and public health problem, making the development of an alternative mean a very urgent issue. Recently, biosynthesis of silver nanoparticles (AgNPs) was successfully accomplished in the presence of Eucalyptus citriodora leaf extract as a reducing agent. In this study, the antimicrobial mechanisms of AgNPs against important hospital‐acquired pathogens, including Gram‐positive, Gram‐negative bacteria, and fungi were further assessed. The results indicated that AgNPs could enhance a broad antimicrobial spectrum against drug‐resistant organisms, with a range of minimum inhibitory concentration from 0.02 to 0.36 μg/mL. Time‐kill assay showed that AgNPs produced bactericidal effects on the microorganisms. AgNPs could significantly reduce biofilm production in pathogens without affecting growth of the pathogens (p < 0.05). AgNPs inhibited cell viability and biofilm formation in a dose‐dependent manner. Cell membrane damage in microorganisms resulting from effects of AgNPs was observed. A significant increase in per cent uptake of crystal violet was observed in all isolates treated with AgNPs when compared with the control (p < 0.05). Upon treatment with AgNPs, the surface charge of the reference strains and clinical isolates of pathogens moved towards neutral. The alteration of surface potential after exposure to AgNPs could contribute to membrane disruption and cell viability. Scanning electron microscopy further confirmed morphological cell changes and disrupted the cell membrane. Increasing resistance to AgNPs was not induced by stepwise isolation of the bacteria after 45 passages on Luria‐Bertani agar supplemented with AgNPs. Furthermore, AgNPs was not toxic to red blood cells.
Eleutherine americana, a well‐known Asian medicinal herb, has been claimed for many biological ac... more Eleutherine americana, a well‐known Asian medicinal herb, has been claimed for many biological activities. In this study, potential of E. americana ethanolic extract against adhesion and invasion of Caco‐2 cells by commonly contaminated Campylobacter spp. was evaluated. MIC₅₀ values of E. americana extract against 39 enteritis patient and 26 chicken isolates were 125 µg/ml. Two models were set up: Model I, Prevention: Preincubation of E. americana extract with campylobacters before adding to Caco‐2 cells. Adhesion to and invasion of Caco‐2 cells by campylobacters were completely inhibited within 12 hr. Model II, Treatment: Preincubation of the organisms with Caco‐2 cells before adding the extract. Adding the extract after the bacteria were mixed with Caco‐2 cells resulted in moderate effect on adhesion, but complete prevention of penetration of the organisms into Caco‐2 cells was observed. The extract at the highest concentration tested (250 μg/ml) demonstrated no cytotoxicity toward Caco‐2 cells. PRACTICAL APPLICATIONS: Eleutherine americana bulb extract could be applied as an effective food preservative to control campylobacter contamination at initial stage in food chain. In addition, the extract provides a curative approach to campylobacter infections.
Endotracheal tubes (ETTs) are a common source of bacterial colonization, leading to ventilator-as... more Endotracheal tubes (ETTs) are a common source of bacterial colonization, leading to ventilator-associated pneumonia (VAP). This research developed a biofilm-resistant ETT, following the principles of green chemistry. Using an aqueous layer-by-layer (LbL) technique, a thick polyelectrolyte multilayered film was deposited on a ventilation tube. The polyelectrolyte multilayered film accommodated silver nanoparticles (AgNPs) formed in situ by reducing Ag+ ions with Eucalyptus citriodora leaf extract. The multilayered film coating conformed to the curved surfaces of the ETT. Film thickness and silver content increased exponentially with the number of polyelectrolyte bilayer pairs, and a sufficiently high AgNPs content of 10-30%w/w was obtained at 75 to 125 bilayer films. Adhesion of the Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa was prevented by 99.9 and 99.99%, respectively, without cytotoxic effects against human lung epithelial cells (p < 0.05).
Psoriasis is a common skin disease pathogenically driven by TNF and IL-17A-induced epidermal hype... more Psoriasis is a common skin disease pathogenically driven by TNF and IL-17A-induced epidermal hyperproliferation and inflammatory responses. The ongoing need for new therapeutic agents for psoriasis has highlighted medicinal plants as sources of phytochemicals useful for treating psoriatic disease. Rhodomyrtone, a bioactive phytochemical from Rhodomyrtus tomentosa, has well-established anti-proliferative activities. This study assessed the potential of rhodomyrtone for curtailing TNF/IL-17A-driven inflammation. Stimulating human skin organ cultures with TNF+IL-17A to model the skin inflammation in psoriasis, we found that rhodomyrtone significantly decreased inflammatory gene expression and the expression and secretion of inflammatory proteins, assessed by qRT-PCR, immunohistochemistry and ELISA assays respectively. RNA-seq analysis of monolayer primary keratinocytes treated with IL-17A/TNF showed that rhodomyrtone inhibited 724/1587 transcripts >2-fold altered by IL-17A/TNF (p<...
The capacity to resist the bactericidal action of complement (C′) is a strong but poorly understo... more The capacity to resist the bactericidal action of complement (C′) is a strong but poorly understood virulence trait in Klebsiella spp. Killing requires activation of one or more C′ pathways, assembly of C5b-9 membrane attack complexes (MACs) on the surface of the outer membrane (OM), and penetration of MACs into the target bilayer. We interrogated whole-genome sequences of 164 Klebsiella isolates from three tertiary hospitals in Thailand for genes encoding surface-located macromolecules considered to play a role in determination of C′ resistance. Most isolates (154/164) were identified as Klebsiella pneumoniae, and the collection conformed to previously established population structures and antibiotic resistance patterns. The distribution of sequence types (STs) and capsular (K) types were also typical of global populations. The majority (64%) of isolates were resistant to C′, and the remainder were either rapidly or slowly killed. All isolates carried genes encoding capsular polysa...
Particularly in Asia medicinal plants with antimicrobial activity are used for therapeutic purpos... more Particularly in Asia medicinal plants with antimicrobial activity are used for therapeutic purpose. One such plant-derived antibiotic is rhodomyrtone (Rom) isolated from Rhodomyrtus tomentosa leaves. Rom shows high antibacterial activity against a wide range of Gram-positive bacteria, however, its mode of action is still unclear. Reporter gene assays and proteomic profiling experiments in Bacillus subtilis indicate that Rom does not address classical antibiotic targets like translation, transcription or DNA replication, but acts at the cytoplasmic membrane. In Staphylococcus aureus, Rom decreases the membrane potential within seconds and at low doses, causes release of ATP and even the excretion of cytoplasmic proteins (ECP), but does not induce pore-formation as for example nisin. Lipid staining revealed that Rom induces local membrane damage. Rom's antimicrobial activity can be antagonized in the presence of a very narrow spectrum of saturated fatty acids (C15:0, C16:0, or C18...
To determine the anti-Streptococcus mutans mechanisms of action of lupinifolin from Albizia myrio... more To determine the anti-Streptococcus mutans mechanisms of action of lupinifolin from Albizia myriophylla Benth. (Fabaceae) wood and provide scientific evidence to support the traditional use of the plant against dental caries. The minimum inhibitory concentration (MIC) was evaluated using the broth micro-dilution method. The effects of lupinifolin on bactericidal activity, bacterial cell walls, and membranes were investigated by time-kill, lysis, and leakage assays, respectively. Electron microscopy was utilized to observe any cell morphological changes caused by the compound. Localization of lupinifolin in S. mutans was detected using the thin layer chromatography technique. The MIC range of lupinifolin against S. mutans (n=6) was 2-4 μg/ml. This compound displayed bactericidal effects on S. mutans ATCC 25175 by 90-99.9% killing at 4MIC-16MIC after 8-24 hours. Lupinifolin-treated cells demonstrated no lysis. However, significant cytoplasmic leakage through the bacterial membrane was...
Background Quercus infectoria G. Olivier (Fagaceae) nutgalls have been widely employed in traditi... more Background Quercus infectoria G. Olivier (Fagaceae) nutgalls have been widely employed in traditional Asian medicine for several treatments, especially wounds and skin disorders. However, the effects of this plant on wound healing have not yet been clearly elucidated. This present work was focused on utilization of Quercus infectoria (Qi) as a topical agent for chronic wound treatment. Methods Twenty Qi formulations (QiFs) were pharmaceutically formulated and antibacterial activity of all formulations was performed. The best formulation based on an antibacterial activity was selected for evaluation of wound healing property. Total phenolics, total flavonoids, and an anti-oxidant activity of the selected formulation were also investigated. Wound healing activity was assessed in streptozotocin-induced diabetic rats and control rats. Streptozotocin injection (50 mg/kg) was found to induce marked hyperglycaemia, compared with citrate-injected controls. Two wounds were created on the upp...
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Papers by Supayang Voravuthikunchai