Malai Taweechotipatr

Human-Derived Probiotic Lactobacillus reuteri Demonstrate Antimicrobial Activities Targeting Diverse Enteric Bacterial Pathogens

Lactobacillus reuteri is a commensal-derived anaerobic probiotic that resides in the human gastrointestinal tract. L. reuteri converts glycerol into a potent broad-spectrum antimicrobial compound, reuterin, which inhibits the growth of gram-positive and gram-negative bacteria. In this study, we compared four human-derived L. reuteri isolates (ATCC 55730, ATCC PTA 6475, ATCC PTA 4659 and ATCC PTA 5289) in their ability to produce reuterin and to inhibit the growth of different enteric pathogens in vitro. Reuterin was produced by each of the four L. reuteri strains and assessed for biological activity. The minimum inhibitory concentration (MIC) of reuterin derived from each strain was determined for the following enteric pathogens: enterohemorrhagic Escherichia coli, enterotoxigenic E. coli, Salmonella enterica, Shigella sonnei and Vibrio cholerae. We also analyzed the relative abilities of L. reuteri to inhibit enteric pathogens in a pathogen overlay assay. The magnitude of reuterin production did not directly correlate with the relative ability of L. reuteri to suppress the proliferation of enteric pathogens. Additional antimicrobial factors may be produced by L. reuteri, and multiple factors may act synergistically with reuterin to inhibit enteric pathogens.

Evaluation of an ethnopharmacologically selected Bhutanese medicinal plants for their major classes of Phytochemicals and biological activities

ETHNOPHARMACOLOGICAL RELEVANCE As many as 229 medicinal plants have been currently used in the Bhutanese Traditional Medicine (BTM) as a chief ingredient of polyherbal formulations and these plants have been individually indicated for treating various types of infections including malaria, tumor, and microbial. We have focused our study only on seven species of these plants. AIM OF THE STUDY We aim to evaluate the antiplasmodial, antimicrobial, anti-Trypanosoma brucei rhodesiense and cytotoxicity activities of the seven medicinal plants of Bhutan selected using an ethno-directed bio-rational approach. This study creates a scientific basis for their use in the BTM and gives foundation for further phytochemical and biological evaluations which can result in the discovery of new drug lead compounds. MATERIALS AND METHODS A three stage process was conducted which consisted of: (1) an assessment of a pharmacopoeia and a formulary book of the BTM for their mode of plant uses; (2) selecting 25 anti-infective medicinal plants based on the five established criteria, collecting them, and screening for their major classes of phytochemicals using appropriate test protocols; and (3) finally analyzing the crude extracts of the seven medicinal plants, using the standard test protocols, for their antiplasmodial, antimicrobial, anti-Trypanosoma brucei rhodesiense and cytotoxicity activities as directed by the ethnopharmacological uses of each plant. RESULTS Out of 25 medicinal plants screened for their major classes of phytochemicals, the majority contained tannins, alkaloids and flavonoids. Out of the seven plant species investigated for their biological activities, all seven of them exhibited mild antimicrobial properties, five plants gave significant in vitro antiplasmodial activities, two plants gave moderate anti-Trypanosoma brucei rhodesiense activity, and one plant showed mild cytotoxicity. Meconopsis simplicifolia showed the highest antiplasmodial activity with IC(50) values of 0.40 μg/ml against TM4/8.2 strain (a wild type chloroquine and antifolate sensitive strain) and 6.39 μg/ml against K1CB1 (multidrug resistant strain) strain. Significantly the extracts from this plant did not show any cytotoxicity. CONCLUSIONS These findings provide the scientific basis for the use of seven medicinal plants in the BTM for the treatment of malaria, microbial infections, infectious fevers, and the Trypanosoma brucei rhodesiense infection. The results also form a good preliminary basis for the prioritization of candidate plant species for further in-depth phytochemical and pharmacological investigations toward our quest to unearth lead antiparasitic, anticancer and antimicrobial compounds.

Lactobacillus saerimneri and Lactobacillus ruminis: novel human‐derived probiotic strains with immunomodulatory activities

Human-derived lactobacilli were isolated from fecal samples of healthy volunteers. Forty-six isolates from different volunteers were selected and investigated for their immunomodulatory properties. Conditioned medium from each isolate was assessed for its effect on tumor necrosis factor (TNF) production in lipopolysaccharide-activated THP-1 monocytes. Of 46 Lactobacillus isolates, 12 significantly inhibited TNF production in varying magnitude. Lactobacillus strain TH58 displayed the most potent TNF-inhibitory activity (70% inhibition). In contrast, Lactobacillus strain TH14 exhibited immunostimulatory property by activating TNF production in THP-1 monocytes. Lactobacillus TH14 induced nuclear factor-kappaB (NF-kappaB) activation in the absence of lipopolysaccharide stimulation, whereas Lactobacillus TH58 had no effect on NF-kappaB signaling, irrespective of lipopolysaccharide stimulation. Strain TH58 was identified as Lactobacillus saerimneri and strain TH14 as Lactobacillus ruminis by sequence analysis of their 16S rRNA genes. This is the first report of a human isolate of L. saerimneri with TNF-inhibitory activity and L. ruminis, an indigenous species to humans, with TNF stimulatory activity. Our data suggest the potential use of these two strains as immunoprobiotic candidates.

Inhibition of TNF-α production in LPS-activated THP-1 monocytic cells by the crude extracts of seven Bhutanese medicinal plants

ETHNOPHARMACOLOGICAL RELEVANCE Seven studied medicinal plants; Aconitum laciniatum, Ajania nubigena, Codonopsis bhutanica, Corydalis crispa, Corydalis dubia, Meconopsis simplicifolia and Pleurospermum amabile, are currently used in the Bhutanese Traditional Medicine (BTM) for the management of different types of disorders including the diseases that bore relevance to various inflammatory conditions. AIMS OF THE STUDY This study aimed to evaluate the inhibition of TNF-α production in LPS-activated THP-1 monocytic cells by the crude extracts of seven selected Bhutanese medicinal plants. It is expected to; (a) generate a scientific basis for their use in the BTM and (b) form a basis for prioritization of the seven plants for further phytochemical and anti-inflammatory studies. MATERIALS AND METHODS Seven plants were selected using an ethno-directed bio-rational approach and their crude extracts were prepared using four different solvents (methanol, hexane, dichloromethane and chloroform). The TNF-α inhibitory activity of these extracts was determined by cytokine-specific sandwich quantitative enzyme-linked immunosorbent assays (ELISAs). The results were quantified statistically and the statistical significance were evaluated by GraphPad Prism version 5.01 using Students t-test with one-tailed distribution. A p-value ≤0.05 was considered statistically significant. RESULTS Of the seven plants studied, the crude extracts of six of them inhibited the production of pro-inflammatory cytokine, TNF-α in LPS-activated THP-1 monocytic cells. Amongst the six plants, Corydalis crispa gave the best inhibitory activity followed by Pleurospermum amabile, Ajania nubigena, Corydalis dubia, Meconopsis simplicifolia and Codonopsis bhutanica. Of the 13 extracts that exhibited statistically significant TNF-α inhibitory activity (p<0.05; p<0.01), five of them showed very strong inhibition when compared to the DMSO control and RPMI media. CONCLUSIONS Six medicinal plants studied here showed promising TNF-α inhibitory activity. These findings rationalize the traditional use of these selected medicinal plants in the BTM as an individual plant or in combination with other ingredients for the treatment of disorders bearing relevance to the inflammatory conditions. The results forms a good preliminary basis for the prioritization of candidate plant species for an in-depth phytochemical study and anti-inflammatory activity screening of the pure compounds contained within those seven plants.