Antistaphylococcal and biofilm inhibitory activities of acetyl-11-keto-β-boswellic acid from Boswellia serrata

<p>Abstract</p> <p>Background</p> <p>Boswellic acids are pentacyclic triterpenes, which are produced in plants belonging to the genus <it>Boswellia</it>. Boswellic acids appear in the resin exudates of the plant and it makes up 25-35% of the resin. β-boswellic acid, 11-keto-β-boswellic acid and acetyl-11-keto-β-boswellic acid have been implicated in apoptosis of cancer cells, particularly that of brain tumors and cells affected by leukemia or colon cancer. These molecules are also associated with potent antimicrobial activities. The present study describes the antimicrobial activities of boswellic acid molecules against 112 pathogenic bacterial isolates including ATCC strains. Acetyl-11-keto-β-boswellic acid (AKBA), which exhibited the most potent antibacterial activity, was further evaluated in time kill studies, postantibiotic effect (PAE) and biofilm susceptibility assay. The mechanism of action of AKBA was investigated by propidium iodide uptake, leakage of 260 and 280 nm absorbing material assays.</p> <p>Results</p> <p>AKBA was found to be the most active compound showing an MIC range of 2-8 μg/ml against the entire gram positive bacterial pathogens tested. It exhibited concentration dependent killing of <it>Staphylococcus aureus </it>ATCC 29213 up to 8 × MIC and also demonstrated postantibiotic effect (PAE) of 4.8 h at 2 × MIC. Furthermore, AKBA inhibited the formation of biofilms generated by <it>S. aureus </it>and <it>Staphylococcus epidermidis </it>and also reduced the preformed biofilms by these bacteria. Increased uptake of propidium iodide and leakage of 260 and 280 nm absorbing material by AKBA treated cells of <it>S aureus </it>indicating that the antibacterial mode of action of AKBA probably occurred via disruption of microbial membrane structure.</p> <p>Conclusions</p> <p>This study supported the potential use of AKBA in treating <it>S. aureus </it>infections. AKBA can be further exploited to evolve potential lead compounds in the discovery of new anti-Gram-positive and anti-biofilm agents.</p

Tandem Catalysis by Lipase in a Vinyl Acetate-Mediated Cross-Aldol Reaction

The lipase Novozym435 (0.6% w/w) was used in tandem with organocatalysts in a first vinyl/isopropenyl acetate-mediated aldol reaction. The reaction was facilitated through the lipase-catalyzed in situ generation of acetaldehyde/acetone. The importantfeatures of the present methodology include the mild and facile reaction conditions, regenerability of the lipase, comparatively high yields and minimal side product formation

2,3-Unsaturated Allyl Glycosides as Glycosyl Donors for Selective α-Glycosylation

In the presence of NBS and a catalytic amount of a Lewis acid, 2,3-unsaturated allyl glycosides [6-(allyloxy)-3,6-dihydro-2-(hydroxymethyl)-2H-pyran-3-ol] have been successfully used as versatile glycosyl donors for the stereoselective R-glycosylation of a variety of alcohols comprising sensitive functions such as acetonide, keto, nitro, and ester in 50�90% yields. The methodology offers an equally facile alternative to 4-pentenyl replacement in unsaturated sugars

Lipase-catalyzed Separation of Geometrical Isomers: Geraniol 13Nerol

The substrate/lipase ratio as well as pH of the buffer medium played important roles in the resolution of geometrical isomeric mixture of geraniol 13nerol. Based on the results, an immobilized lipase from Pseudomonas fluorescens (PFL) was found effective in selective transesterifications whereas Pseudomonas sp. Lipase (PSL) was found to be useful in hydrolyzing the esters

Semi-synthetic analogs of pinitol as potential inhibitors of TNF-α cytokine expression in human neutrophils

Semi-synthetic analogs of pinitol were subjected to screening by determining TNF-a expression in human neutrophils using flowcytometry. Among the tested compounds, three derivatives displayed more than 50% inhibition of TNF-a cytokine secretion in LPS induced stimulated neutrophils and can be considered as potent anti-inflammatory moieties

1,2,3,4,5,6-Hexa-O-acetyl-scyllo-inositol

The title molecule, C18H24O12, has crystallographic 2/m symmetry with two acetate group located on a mirror plane. The H&amp;#8212;Csp3&amp;#8212;O&amp;#8212;Csp2 torsion angles characterizing orientation of the acetyl groups with respect to the cyclohexane ring are 0.0, 23.9 and &amp;#8722;23.9&amp;#176;. The cyclohexane ring is in a chair conformation with all substituents in equatorial positions. In the crystal, molecules are connected through C&amp;#8212;H...O hydrogen bonds into a chain extending along the c axis

An expedient chemo-enzymatic method for the synthesis of optically active masked 1,2-amino alcohols

The expedient synthesis of enantiopure masked 1,2-amino alcohols (ee >99%) including their alkyl substituted analogues has been achieved by the regioselective ring opening of epoxides using phthalimide,followed by highly efficient kinetic resolution under mild and environmentally friendly conditions. The addition of co-solvents during kinetic resolution significantly improved the enantioselectivity with reduction in time