Biofilm Inhibition via Delivery of Novel Methylthioadenosine Nucleosidase Inhibitors from PVA-Tyramine Hydrogels while Supporting Mesenchymal Stromal Cell Viability.

The rise of antibiotic resistance, coupled with increased expectations for mobility in later life, is creating a need for biofilm inhibitors and delivery systems that will reduce surgical implant infection. A limitation of some of these existing delivery approaches is toxicity exhibited toward host cells. Here, we report the application of a novel inhibitor of the enzyme, methylthioadenosine nucleosidase (MTAN), a key enzyme in bacterial metabolic pathways, which include S-adenosylmethionine catabolism and purine nucleotide recycling, in combination with a poly(vinyl alcohol)-tyramine-based (PVA-Tyr) hydrogel delivery system. We demonstrate that a lead MTAN inhibitor, selected from a screened library of 34 candidates, (2S)-2-(4-amino-5H-pyrrolo3,2-dpyrimidin-7-ylmethyl)aminoundecan-1-ol (31), showed a minimum biofilm inhibitory concentration of 2.2 ± 0.4 µM against a clinical staphylococcal species isolated from an infected implant. We observed that extracellular DNA, a key constituent of biofilms, is significantly reduced when treated with 10 µM compound 31, along with a decrease in biofilm thickness. Compound 31 was incorporated into a hydrolytically degradable photo-cross-linked PVA-Tyr hydrogel and the release profile was evaluated by HPLC studies. Compound 31 released from the PVA-hydrogel system significantly reduced biofilm formation (77.2 ± 8.4% biofilm inhibition). Finally, compound 31 released from PVA-Tyr showed no negative impact on human bone marrow stromal cell (MSC) viability, proliferation, or morphology. The results demonstrate the potential utility of MTAN inhibitors in treating infections caused by Gram-positive bacteria, and the development of a nontoxic release system that has potential for tunability for time scale of delivery.

Chemical composition and cytotoxicity of oils and eremophilanes derived from various parts of Eremophila mitchellii Benth. (Myoporaceae).

A detailed investigation of the wood, leaf, branch and root oil of Eremophila mitchellii (Benth.) was carried out by a combination of GC-FID, GC-MS and NMR. The wood oil was composed predominantly of eremophilanes, a rare class of biologically active, bicyclic sesquiterpenoids. The root oil was also found to contain the eremophilanes together with the zizaene sesquiterpene, sesquithuriferone. 9-Hydroxy-1,7(11),9-eremophilatrien-8-one and the known 1(10),11-eremophiladien-9-one (eremophilone), 9-hydroxy-7(11),9-eremophiladien-8-one (2-hydroxyeremophilone), 8-hydroxy-11-eremophilen-9-one (santalcamphor), 8-hydroxy-10,11-eremophiladien-9-one, sesquithuriferone and 8-hydroxy-1,11-eremophiladien-9-one were purified and elucidated by NMR. Three approaches to the purification of the major eremophilanes from the wood oil are described. (+) Spathulenol, α-pinene, globulol, viridiflorene were the major constituents of the leaf oil. All of the essential oils and the eremophilanes exhibited cytotoxicity against P388D(1) mouse lymphoblast cells in-vitro.

Diarylheptanoid from Pleuranthodium racemigerum with in vitro prostaglandin E(2) inhibitory and cytotoxic activity.

Bioactivity-guided fractionation of an ethanolic extract of the rhizome of Pleuranthodium racemigerum, a tropical Zingiberaceae species from Northeastern Australia, resulted in the isolation and structural elucidation of 1-(4''-methoxyphenyl)-7-(4'-hydroxyphenyl)-(E)-hept-2-ene (1), a new diarylheptanoid related to curcumin. Compound 1 was a fairly potent inhibitor of prostaglandin E(2) production in 3T3 murine fibroblasts (IC(50) approximately 34 microM) and also displayed moderate cytotoxicity against this cell line (IC(50) = 52.8 microM). The compound also demonstrated cytotoxic activity against the P388D1 murine lymphoblast cell line (IC(50) = 117.0 microM) and four human cell lines: Caco-2 colonic adenocarcinoma (IC(50) = 44.8 microM), PC3 prostate adenocarcinoma (IC(50) = 23.6 microM), HepG2 hepatocyte carcinoma (IC(50) = 40.6 microM), and MCF7 mammary adenocarcinoma (IC(50) = 56.9 microM). The cytotoxicity of compound 1 closely resembled that of curcumin, in terms of both IC(50) values and dose-response curves.