Lichenochemicals: extraction, purification, characterization, and application as potential anticancer agents.

Introduction: To date, over 1,000 lichen secondary metabolites have been identified. Despite their promising cytotoxic properties, the number of literature reports on anticancer evaluation of lichenochemicals is limited. As cancer prevalence among the human population increases, there is growing interest in lichens as a natural source of secondary metabolites for anti-cancer drug discovery and development.Areas covered: The lack of significant progress in lichen anticancer research is due to the low levels of cytotoxic compounds contained in lichens, the technical difficulties associated with their isolation and characterization, and the insufficient understanding of their mechanism of action on different cancer cell lines. In this review, the authors discuss these challenges and provide systematically organized information on the limitations and advantages of commonly used and newly developed methods for lichen exploration and screening of lichen secondary metabolites for their anticancer potential.Expert opinion: Recent research activities have demonstrated that lichen secondary metabolites possess chemotherapeutic properties. A systematic and multidisciplinary approach is required to advance lichen research and improve our understanding of the mechanisms responsible for the potent cytotoxic properties of lichenochemicals. More efforts need to focus on screening and discovery of new lichen-derived compounds with unique anticancer properties.

Antioxidant, Antibacterial, and Cytotoxic Activities of the Ethanolic Origanum vulgare Extract and Its Major Constituents.

Oregano is a perennial shrub that grows in the mountains of the Mediterranean and Euro/Irano-Siberian regions. This study was conducted to identify the major constituents of the ethanolic Origanum vulgare extract and examine the cytotoxic, antioxidant, and antibacterial properties of the extract but more importantly the contribution of its specific major constituent(s) or their combination to the overall extract biological activity. Gas chromatography/mass spectroscopy analysis showed that the extract contained monoterpene hydrocarbons and phenolic compounds, the major ones being carvacrol and thymol and to a lesser extent p-cymene, 1-octacosanol, creosol, and phytol. A549 epithelial cells challenged with the extract showed a concentration-dependent increase in cytotoxicity. A combination of thymol and carvacrol at equimolar concentrations to those present in the extract was less cytotoxic. The A549 cells pretreated with nonlethal extract concentrations protected against hydrogen-peroxide-induced cytotoxicity, an antioxidant effect more effective than the combination of equimolar concentrations of thymol/carvacrol. Inclusion of p-cymene and/or 1-octacosanol did not alter the synergistic antioxidant effects of the carvacrol/thymol mixture. The extract also exhibited antimicrobial properties against Gram-positive and Gram-negative bacterial strains including clinical isolates. In conclusion, the oregano extract has cytotoxic, antioxidant, and antibacterial activities mostly attributed to carvacrol and thymol.

The effects of antioxidant vitamin supplementation on resistance exercise induced lipid peroxidation in trained and untrained participants.

BACKGROUND: The theoretical benefits of using antioxidant vitamin supplements to quench oxygen free radicals appear large. High intensity aerobic-type exercise produces oxygen free radicals that can cause damage to lipid membranes (lipid peroxidation) that may lead to many problems such as the inactivation of cell membrane enzymes, the progression of degenerative diseases (cardiovascular disease and cancer) and lessening of the effectiveness of the immune system. The major function of vitamin E is to work as a chain-breaking antioxidant in a fat soluble environment. Little research has examined lipid peroxidation associated with high intensity resistance exercise or possible protective effects of antioxidant supplementation or the effects of training state. RESULTS: There were no significant group (trained vs untrained) or treatment (vitamin E vs placebo) effects found between the 4 groups assessed. There was only one significant difference found and that was in the main effect for time (F = 22.41, p < 0.01). CONCLUSIONS: The Resistance Exercise Test caused a significant increase in malondialdehyde in all 4 groups at 6 hours post exercise. There was no evidence that vitamin E supplementation was effective in reducing oxidative damage in comparison to the placebo group. As well, there was no difference between the trained and untrained groups with respect to their impact on lipid peroxidation measures.

Comparison of various methods of electromyographic monitoring of the recurrent laryngeal nerve in thyroid surgery.

In the present study, 3 types of electrodes for recurrent laryngeal nerve (RLN) monitoring are compared: 1) intralaryngeal surface electrodes attached to a conventional endotracheal tube, 2) monopolar needle electrodes placed on the vocal cords by direct laryngoscopy, and 3) bipolar needle electrodes inserted intraoperatively through the cricothyroid ligament. Data were collected from stimulation of 21 RLNs in 16 patients undergoing thyroid surgery. The reliability in terms of distinct electromyographic (EMG) potentials following stimulation of the RLN was 100% with monopolar and bipolar needle electrodes and 76% with intralaryngeal surface electrodes. The mean (+/-SD) amplitudes of the EMG potentials were 1.61 +/- 1.6 mV, 2.37 +/- 1.8 mV, and 0.35 +/- 0.4 mV for the monopolar endolaryngeal, bipolar transligament, and intralaryngeal surface electrodes, respectively. The advantages and disadvantages of each type of electrode are discussed.

Synthesis of Terpenoids Using a Free Radical Fragmentation/Elimination Sequence.

Total syntheses of the guaiane alismol 8 and the trinor-guaiane dictamnol 18 are reported. In both syntheses the initial [2+2] photoadduct is transformed into an iodo xanthate 14 or a diiodide 27, respectively. In the critical step, the strained bifunctional substrate undergoes a very efficient free radical fragmentation/elimination sequence to give the requisite seven-membered ring with regioselective placement of the two double bonds in that ring. This first alismol synthesis was accomplished in eight steps while the dictamnol synthesis required only six steps. Clarification of the structure of dictamnol is also described.