Isolation and Antibacterial Activity of Indole Alkaloids from Pseudomonas aeruginosa UWI-1.

In this study, we report the first isolation of three antibiotic indole alkaloid compounds from a Pseudomonad bacterium, Pseudomonas aeruginosa UWI-1. The bacterium was batch fermented in a modified Luria Broth medium and compounds were solvent extracted and isolated by bioassay-guided fractionation. The three compounds were identified as (1) tris(1H-indol-3-yl) methylium, (2) bis(indol-3-yl) phenylmethane, and (3) indolo (2, 1b) quinazoline-6, 12 dione. A combination of 1D and 2D NMR, high-resolution mass spectrometry data and comparison from related data from the literature was used to determine the chemical structures of the compounds. Compounds 1-3 were evaluated in vitro for their antimicrobial activities against a wide range of microorganisms using the broth microdilution technique. Compounds 1 and 2 displayed antibacterial activity against only Gram-positive pathogens, although 1 had significantly lower minimum inhibitory concentration (MIC) values than 2. Compound 3 displayed potent broad-spectrum antimicrobial activity against a range of Gram positive and negative bacteria. Several genes identified from the genome of P. aeruginosa UWI-1 were postulated to contribute to the biosynthesis of these compounds and we attempted to outline a possible route for bacterial synthesis. This study demonstrated the extended metabolic capability of Pseudomonas aeruginosa in synthesizing new chemotypes of bioactive compounds.

Antimicrobial cholic acid derivatives from the Pitch Lake bacterium Bacillus amyloliquefaciens UWI-W23.

Six cholic acid derivatives (1-6) were isolated from broth cultures of Bacillus amyloliquefaciens UWI-W23, an isolate from the Trinidad Pitch Lake. The compounds were extracted via solvent extraction and/or XAD resin adsorption and purified using silica gel column chromatography. Their structures were elucidated using 1D, 2D NMR and ESI-MS spectrometry and FT-IR spectrophotometry. One of the compounds, taurodeoxycholate (2) is for the first time being reported from a bacterial source while deoxycholate (4) is for the first time being reported from a Gram-positive bacterium. The other compounds have not been previously isolated from Bacillus spp. viz. cholate (1), taurocholic acid (3); glycodeoxycholic acid (5) and glycocholic acid (6). All six compounds exhibited antimicrobial activity against P. aeruginosa and B. cereus with MICs ranging from 7 to 250 µg/mL. Cholate (1) also showed activity against MRSA (MICs = 125 µg/mL) and glycocholic acid (6) against S. cerevisiae (MICs = 15.6 µg/mL).

Targeted antimicrobial therapy against Streptococcus mutans establishes protective non-cariogenic oral biofilms and reduces subsequent infection / 国际口腔科学杂志·英文版

<p><b>AIM</b>Dental biofilms are complex communities composed largely of harmless bacteria. Certain pathogenic species including Streptococcus mutans (S. mutans) can become predominant when host factors such as dietary sucrose intake imbalance the biofilm ecology. Current approaches to control S. mutans infection are not pathogen-specific and eliminate the entire oral community along with any protective benefits provided. Here, we tested the hypothesis that removal of S. mutans from the oral community through targeted antimicrobial therapy achieves protection against subsequent S. mutans colonization.</p><p><b>METHODOLOGY</b>Controlled amounts of S. mutans were mixed with S. mutans-free saliva, grown into biofilms and visualized by antibody staining and cfu quantization. Two specifically-targeted antimicrobial peptides (STAMPs) against S. mutans were tested for their ability to reduce S. mutans biofilm incorporation upon treatment of the inocula. The resulting biofilms were also evaluated for their ability to resist subsequent exogenous S. mutans colonization.</p><p><b>RESULTS</b>S. mutans colonization was considerably reduced ( +/- 0.4 fold reduction, P=0.01) when the surface was preoccupied with saliva-derived biofilms. Furthermore, treatment with S. mutans-specific STAMPs yielded S. mutans-deficient biofilms with significant protection against further S. mutans colonization (5 minutes treatment: 38 +/- 13 fold reduction P=0.01; 16 hours treatment: 96 +/- 28 fold reduction P=0.07).</p><p><b>CONCLUSION</b>S. mutans infection is reduced by the presence of existing biofilms. Thus maintaining a healthy or "normal" biofilm through targeted antimicrobial therapy (such as the STAMPs) could represent an effective strategy for the treatment and prevention of S. mutans colonization in the oral cavity and caries progression.</p>

Evaluation of the Wound-healing Activity of Ethanolic Extract of Morinda citrifolia L. Leaf.

Morinda citrifolia L. (noni) is one of the most important traditional Polynesian medicinal plants. The primary indigenous use of this plant appears to be of the leaves, as a topical treatment for wound healing. The ethanol extract of noni leaves (150 mg kg(-1) day(-1)) was used to evaluate the wound-healing activity on rats, using excision and dead space wound models. Animals were randomly divided into two groups of six for each model. Test group animals in each model were treated with the ethanol extract of noni orally by mixing in drinking water and the control group animals were maintained with plain drinking water. Healing was assessed by the rate of wound contraction, time until complete epithelialization, granulation tissue weight and hydoxyproline content. On day 11, the extract-treated animals exhibited 71% reduction in the wound area when compared with controls which exhibited 57%. The granulation tissue weight and hydroxyproline content in the dead space wounds were also increased significantly in noni-treated animals compared with controls (P < 0.002). Enhanced wound contraction, decreased epithelialization time, increased hydroxyproline content and histological characteristics suggest that noni leaf extract may have therapeutic benefits in wound healing.

Evaluation of the wound-healing activity of ethanolic extract of morinda citrifolia L. Leaf.

Morinda citrifolia L. (noni) is one of the most important traditional Polynesian medicinal plants. The primary indigenous use of this plant appears to be of the leaves, as a topical treatment for wound healing. The ethanol extract of noni leaves (150 mg kg(-1) day(-1)) was used to evaluate the wound-healing activity on rats, using excision and dead space wound models. Animals were randomly divided into two groups of six for each model. Test group animals in each model were treated with the ethanol extract of noni orally by mixing in drinking water and the control group animals were maintained with plain drinking water. Healing was assessed by the rate of wound contraction, time until complete epithelialization, granulation tissue weight and hydoxyproline content. On day 11, the extract-treated animals exhibited 71 per cent reduction in the wound area when compared with controls which exhibited 57 per cent. The granulation tissue weight and hydroxyproline content in the dead space wounds were also increased significantly in noni-treated animals compared with controls (P < 0.002). Enhanced wound contraction, decreased epithelialization time, increased hydroxyproline content and histological characteristics suggest that noni leaf extract may have therapeutic benefits in wound healing.

Crotogossamide, a cyclic nonapeptide from the latex of Croton gossypifolius.

A new cyclic nonapeptide, crotogossamide (1), was isolated from the latex of Croton gossypifolius. Its structure was elucidated by use of 1D and 2D NMR and MS and by hydrolysis followed by GC-MS analysis as cyclo(-Gly(1)-Ala(2)-Ser(3)-Gly(4)-Leu(5)-Asn(6)-Gly(7)-Ile(8)-Phe(9)-). This is the first report of a cyclic peptide from a Croton species. The known flavonoids kaempferol 3-O-rhamnopyranoside, quercitrin, and myricitrin were also isolated from the plant latex.