Report on the Fifth International Conference on Natural Products for Health and Beauty (NATPRO 5) held in Thailand, 6–8th May, 2014

Excerpt: The 5th International Conference on Natural Products for Health and Beauty (NATPRO 5) was held at the Moevenpick Resort and Spa Karon Beach, Phuket, Thailand on 6–8 May 2014. NATPRO was established in 2005 by Professor Maitree Suttajit, Mahasarakham University with the aim of building research networking on natural products. NATPRO 2, 3 and 4 were subsequently organized by Naresuan University, Rangsit University and Chiang Mai University in 2008, 2011 and 2012, respectively

Effect of Thai medicinal plant extracts on cell aggregation of Escherichia coli O157: H7.

Medicinal plants have been used for treating diarrhoea but the interference mechanisms are not clearly understood. One possible hypothesis is that of an effect on cell surface hydrophobicity of microbial cells. In this study, we examined cell aggregation affected by crude extracts of Thai medicinal plants on cell surface hydrophobicity of Escherichia coli strains by salt aggregation test. Correlation between minimal inhibitory concentration and cell aggregation was performed. Aqueous and ethanolic extracts of 8 medicinal plants including Acacia catechu, Holarrhena antidysenterica, Peltophorum pterocarpum, Piper sarmentosum, Psidium guajava, Punica granatum, Quercus infectoria, and Tamarindus indica were tested with E. coli O157: H7 and other E. coli strains isolated from human, porcine, and foods. Aqueous extracts of Peltophorum pterocarpum, Psidium guajava, and Punica granatum were highly effective against E. coli O157: H7 with the MIC values of 0.09 to 0.39, 0.19 to 0.78, and 0.09 to 1.56 mg/ml, respectively. Ethanolic extract of Quercus infectoria and Punica granatum demonstrated good MIC values of 0.09 to 0.78, and 0.19 to 0.78 mg/ml, respectively. It was established that aqueous extracts of Punica granatum and Piper sarmentosum at high concentration (25 mg/ml) enhanced cell aggregation of almost all E. coli strains while aqueous and ethanolic extracts ofQuercus infectoria enhanced cell aggregation of some E. coli strains. Correlation between minimal inhibitory concentration and cell aggregation was not found in this study

Bactericidal, Bacteriolytic, and Antibacterial Virulence Activities of Boesenbergia pandurata (Roxb) Schltr Extract against Streptococcus pyogenes

Purpose: To determine the anti-Streptococcus pyogenes activity of the chloroform extract of Boesenbergia pandurata (Roxb.) Schltr. (Zingiberaceae) and investigate its possible antibacterial mechanisms of action.Methods: Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were investigated against 47 clinical isolates of S. pyogenes. Time-kill study was performed to determine how quickly the extract acts on S. pyogenes. The ability of the extract to damage bacterial cell wall and effects on S. pyogenes virulence factors including protease enzyme and haemolysin were investigated.Results: The extract exhibited good antibacterial activity against all of the clinical isolates of S. pyogenes with similar MIC and MBC ranging from 3.91-62.50 μg/ml. Complete killing of the bacterial cells by the extract at concentrations of 4MIC, 2MIC, and MIC occurred within 4, 8, and 12 h, respectively. Treatment of the bacterial cells with the extract at 2MIC and 4MIC caused cell lysis. All the test concentrations (1/32 - 1/2MIC) produced no effects on protease and haemolysin enzymes.Conclusion: Boesenbergia pandurata extract has powerful in vitro activity against S. pyogenes. The ability of the extract to lyse the bacterial cells suggests that the mechanism of action may be associated with cell wall and cell membrane damage.Keywords: Antibacterial, Bacteriocidal, Bacteriolytic, Virulence, Boesenbergia pandurata, Streptococcus pyogenes

Antibacterial activity of crude extracts of Thai medicinal plants against clinical isolates of methicillin-resistant Staphylococcus aureus

Aqueous and ethanolic extracts of Acacia catechu, Garcinia mangostana, Impatiens balsamina, Peltophorum pterocarpum, Psidium guajava, Punica granatum, Quercus infectoria, Tamarindus indica, Uncaria gambir, Walsura robusta were primarily tested for their antibacterial activities against 35 clinical isolates of methicillin-resistant S. aureus and S. aureus ATCC 25923 using disc diffusion method (2.5 mg/disc). Almost all extracts, except Tamarindus indica exhibited antibacterial activity. Both aqueous and ethanolic extracts of Acacia catechu, Psidium guajava, Punica granatum, Quercus infectoria, and Uncaria gambir, and ethanolic extracts of Garcinia mangostana, Impatiens balsamina, Peltophorum pterocarpum, and Walsura robusta demonstrated inhibition zones, ranging from 6 to 22 mm. Determination of minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values were performed using agar dilution method. The MIC/MBC values of aqueous extracts of Quercus infectoria against clinical isolates of MRSA and S. aureus were 0.2 to 0.4/0.4 to 1.6 and 0.2/1.6 mg/ ml, respectively. Ethanolic extracts of Garcinia mangostana, Punica granatum and Quercus infectoria were demonstrated to be the most effective. The MIC values against MRSA isolates and S. aureus ranged from 0.05 to 0.4 and 0.1, 0.2 to 0.4 and 0.1, 0.2 to 0.4 and 0.2 mg/ml, respectively. The MBC values against MRSA ranged from 0.1 to 0.4, 0.4 to 1.6, and 1.6 to 3.1 mg/ml and against S. aureus at 0.4, 3.2, and 1.6 mg/ml, respectively

Anti-Streptococcus pyogenes Activity of Selected Medicinal Plant Extracts Used in Thai Traditional Medicine

Purpose: To evaluate the anti-Streptococcus pyogenes activity of selected medicinal plants used in Thai traditional medicine.Methods: Sixty-nine extracts of 51 selected Thai medicinal plant species were tested for anti-S. pyogenes activity by paper disc agar diffusion and broth microdilution methods.Results: Ten plants including Boesenbergia pandurata (Roxb.) Schltr., Cinnamomum bejolghota (Buch.-Ham.) Sweet, Cinnamomum porrectum (Roxb) Kosterm, Eleutherine americana Merr., Gymnopetalum cochinchinensis (Lour.) Kurz, Piper betle L., Quercus infectoria G. Olivier, Quisqualis indica L, Rhodomyrtus tomentosa (Aiton) Hassk., and Walsura robusta Roxb. demonstrated good antibacterial activity against S. pyogenes NPRC 101. These plants were selected and further evaluated for their anti-S. pyogenes activity against 11 isolates of S. pyogenes from patients with upper respiratory tract infections. Three plants including Boesenbergia pandurata, Eleutherine americana, and Rhodomyrtus tomentosa exhibited good antibacterial activity against all S. pyogenes isolates and produced similar activities against different tested isolates. Boesenbergia pandurata and Rhodomyrtus tomentosa demonstrated antibacterial activity with the same minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) range of 3.91 - 31.25 μg/ml whereas Eleutherine americana displayed MIC and MBC values of 250 and 250-500 μg/ml against all S. pyogenes isolates.Conclusion: Boesenbergia pandurata, Eleutherine americana, and Rhodomyrtus tomentosa have great antibacterial potentials against S. pyogenes.Keywords: Antibacterial activity, Boesenbergia pandurata, Eleutherine americana, Rhodomyrtus tomentosa, Streptococcus pyogenes, Thai medicinal plant, Upper respiratory tract infection

Thai ethnomedicinal plants as resistant modifying agents for combating Acinetobacter baumannii infections

ABSTRACTS: BACKGROUND: Acinetobacter baumannii is well-recognized as an important nosocomial pathogen, however, due to their intrinsic resistance to several antibiotics, treatment options are limited. Synergistic effects between antibiotics and medicinal plants, particularly their active components, have intensively been studied as alternative approaches. METHODS: Fifty-one ethanol extracts obtained from 44 different selected medicinal plant species were tested for resistance modifying agents (RMAs) of novobiocin against A. baumannii using growth inhibition assay. RESULTS: At 250 μg/ml, Holarrhena antidysenterica, Punica granatum, Quisqualis indica, Terminalia bellirica, Terminalia chebula, and Terminalia sp. that possessed low intrinsic antibacterial activity significantly enhanced the activity of novobiocin at 1 μg/ml (1/8xminimum inhibitory concentration) against this pathogen. Holarrhena antidysenterica at 7.8 μg/ml demonstrated remarkable resistant modifying ability against A. baumannii in combination with novobiocin. The phytochemical study revealed that constituents of this medicinal plant contain alkaloids, condensed tannins, and triterpenoids. CONCLUSION: The use of Holarrhena antidysenterica in combination with novobiocin provides an effective alternative treatment for multidrug resistant A. baumannii infections

Evaluation of a Rhodomyrtus tomentosa ethanolic extract for its therapeutic potential on Staphylococcus aureus infections using in vitro and in vivo models of mastitis

International audienceAbstractAn ethanolic extract from Rhodomyrtus tomentosa leaves (RTL) was studied as a natural alternative to control Staphylococcus aureus, which is an important pathogen responsible for bovine mastitis. The minimal inhibitory concentrations (MICs) of the RTL extract and of rhodomyrtone, a pure compound isolated from the plant, were determined by a microdilution method. Rhodomyrtone and the RTL extract exhibited antibacterial activity against S. aureus, including its persistent phenotype (SCV: small-colony variant) and a biofilm hyperproducer strain, with MICs of 0.25–0.5 and 8–16 µg/mL, respectively. Time-kill kinetics showed a strong bactericidal activity for both the RTL extract- and rhodomyrtone-treated bacteria at 2 × MIC as early as 4 h post-exposure. An additive effect of the extract at 0.5 × MIC was observed in a combination with oxytetracycline or pirlimycin against S. aureus by showing a 64- to 128-fold reduction in antibiotic MICs. Moreover, the RTL extract significantly decreased the number of intracellular SCVs inside bovine mammary epithelial cells. However, the extract or its combination with pirlimycin only slightly improved the activity of pirlimycin against the bacterial colonization of mouse mammary glands. In vitro MICs determined in the presence of casein indicated that the limited activity of the RTL extract in the murine model of mastitis could be linked to neutralization of active components by milk proteins. While the RTL extract showed interesting antibacterial properties in vitro, to be considered as an alternative to antibiotics in dairy farms, formulation studies are needed to cope with the observed reduction of activity in vivo

Synergistic effects of ethnomedicinal plants of Apocynaceae family and antibiotics against clinical isolates of Acinetobacter baumannii

AbstractObjectiveTo investigate the efficacy of 17 ethnomedicinal plants belonging to Apocynaceae family used in combination with 16 conventional antibiotics against non-multidrug resistant-, multidrug resistant (MDR)-, and extensive drug resistant (XDR) Acinetobacter baumannii (A. baumannii).MethodsAntibacterial activity and resistance modifying ability of 272 combinations were determined by growth inhibition assays and further confirmed by time-kill assay.ResultsAmong the combinations of the antibiotics with Apocynaceae ethanol extracts on this pathogen, 15 (5%) had synergistic effects, 23 (8%) had partial synergistic effects and 234 (86%) had no effects. Synergistic activity was observed mostly when the Apocynaceae extracts were combined with rifampicin or cefazolin. Interestingly, 10 out of 17 combinations between the extracts and rifampicin displayed synergistic or partial synergistic behaviors. Holarrhena antidysenterica extract was additionally tested to restore rifampicin activity against clinical isolates of MDR and XDR A. baumannii. With respect to total or partial synergy, 70% was XDR A. baumannii isolates and 66% was MDR A. baumannii isolates.ConclusionsHolarrhena antidysenterica extract clearly demonstrated the ability to restore rifampicin activity against both A. baumannii ATCC19606 and clinically isolated A. baumannii. Additional studies examining its active principles as well as mechanisms of actions such as the effects on efflux pumps and outer membrane permeability alterations are recommended

In vivo safety assessment of rhodomyrtone, a potent compound, from Rhodomyrtus tomentosa leaf extract

This research was funded by the Thailand Research Fund Senior Research Scholar (Grant number RTA6180006).Background Rhodomyrtus tomentosa (Aiton) Hassk. has been traditionally used to relieve various diseases. Rhodomyrtone, a bioactive acylphloroglucinol compound isolated from the leaves of Rhodomyrtus tomentosa, has been scientifically evidenced as a potential antibacterial agent. This study aimed to assess safety of rhodomyrtone in both invertebrate and vertebrate models. Material and Methods Safety of rhodomyrtone was determined in an invertebrate model, Galleria mellonella as well as vertebrate models including zebrafish (Danio rerio) and murine. In addition, toxicity to human erythrocytes was also measured. Results Treatment of Galleria mellonella with rhodomyrtone at 100 mg/kg body weight up to four days showed no visible toxic effects (100 % survival). In zebrafish embryo model, at least 80 % survival of embryos was demonstrated when treated with rhodomyrtone at 0.5 μg/mL for three days. Prior to clinical trial, it is a prerequisite that rhodomyrtone has to be evaluated for its biocompatibility with human blood components. The results displayed that rhodomyrtone at 256 μg/mL did not cause any observable human erythrocyte haemolysis. Furthermore, preclinical assessment of rhodomyrtone formulation justified potential applications of rhodomyrtone in humans. Oral toxicity testing in a mouse model indicated the absence of systemic toxicity when the animals received up to 5000 mg/kg body weight of rhodomyrtone formulation for a period of fourteen days. Conclusions As the minimal inhibitory concentration of rhodomyrtone against most Gram-positive pathogens is 0.5−1 μg/mL, the results suggest that it should produce no toxic effects at concentrations used in human, thus support further development in pharmaceutical industries and public health applications.Publisher PDFPeer reviewe