Antimicrobial activity

Antimetastatic activity Antimicrobial action Antimicrobial activity... 

Strandberg E, Ulrich AS (2004) NMR methods for studying membrane-active antimicrobial peptides. Concepts Magn Reson A 23A 89-120... 

The capsules contained a mean of 82 mg feverfew and thus the level of activity calculated as parthenolide can be estimated as 0.67%. Other studies quote 0.87% sesquiterpene lactones calculated as parthenolide [27] and 0.25-0.30% of active (antimicrobial) material [33]. Bohlmann s extraction of individual components from the dried plant yielded 116 mg sesquiterpene lactones/kg dried feverfew which amounts to less than 0.01 % [17]. Another extraction yielded 330 mg endoperoxides/kg and 56 mg canin/kg alone [19] which would amount to a level of sesquiterpene lactones of at least 0.04%. Thus, the level of sesquiterpene lactones appears to vary with different sources of the plant and this could have been due to a number of factors including the conditions in which feverfew was grown, the season in which it was picked and the way in which it was stored. Another important determinant of the parthenolide content of feverfew appears to be the geographical location. A recent survey of commercial preparations found that all the North American commercial products tested contained less that 0.1% parthenolide, wheras much higher values were obtained for British products. A minimum level of 0.2% parthenolide in commercial products has been proposed by the Health Protection Branch of Health and Welfare Canada [71]. 

Figure 1.1. Opposite) Sulpha drugs and their mode of action. The first sulpha drug to be used medically was the red dye prontosil rubrum (a). In the early 1930s, experiments illustrated that the administration of this dye to mice infected with haemolytic streptococci prevented the death of the mice. This drug, while effective in vivo, was devoid of in vitro antibacterial activity. It was first used clinically in 1935 under the name Streptozon. It was subsequently shown that prontosil rubrum was enzymatically reduced by the liver, forming sulphanilamide, the actual active antimicrobial agent (b). Sulphanilamide induces its effect by acting as an anti-metabolite with respect to /iflra-aminobenzoic acid (PABA) (c). PABA is an essential component of tetrahydrofolic acid (THF) (d). THF serves as an essential co-factor for several cellular enzymes. Sulphanilamide (at sufficiently high concentrations) inhibits manufacture of THF by competing with PABA. This effectively inhibits essential THF-dependent enzyme reactions within the cell. Unlike humans, who can derive folates from their diets, most bacteria must synthesize it de novo, as they cannot absorb it intact from their surroundings...

Decraene, V., Pratten, J., and Wilson, M. (2008a). Novel light-activated antimicrobial coatings are effective against surface-deposited Staphylococcus aureus. Curr. Microbiol. 57, 269-273. 

A number of studies have focused on identifying the active antimicrobial principles in fresh garlic extract. Allicin has been identified as the active agent in garlic extracts. The antifungal activity of allicin has been shown to depend on the sulfhydryl moiety because activity is destroyed by thiols such as L-cysteine, glutathione, and mercaptoethanol. Ajoene, a compound found in oil-macerated garlic, has also been shown to have antimicrobial activity (Ali et al., 2000). 

Another kind of contact-active antimicrobial surface was achieved by tethering antimicrobial peptides to surfaces [62], If such peptides were exclusively membrane-active they could not work like in solution but would be immobilized via a polymeric spacer that could potentially cross the cell wall. The latter was demonstrated by the group of Dathe, who immobilized cationic antimicrobial peptides on PentaGels [63], Also, the well-known antimicrobial peptide magainin I... 

Waschinski CJ, Zimmermann J, Salz U et al. (2008) Design of contact-active antimicrobial acrylate-based materials using biocidal macromers. Adv Mater 20 104-108... 

Wilson M (2003) Light-activated antimicrobial coating for the continuous disinfection of surfaces. Infect Control Hosp Epidemiol 24 782-784... 

Bozja J, Sherrill J, Michielsen S et al. (2003) Porphyrin-based, light-activated antimicrobial materials. J Polym Sci A Polym Chem 41 2297-2303... 

Shai, Y. (2002) Mode of action of membrane active antimicrobial peptides. Biopolymers 66, 236-248. 

The utilization and activity (antimicrobial, antiprotozoan, antibacterial, anti-trichomonal, etc.) of other 2-nitroimidazole derivatives and also 4- and 5-nitroimidazoles are summarized in Table 3. The various activities of nitropyrazoles, nitrotriazoles, nitrotetrazoles, and nitrothiazoles are presented in Table 4. 

Toniolo C, Crisma M, Formaggio F, Peggion C, Epand RF, Epand RM. Lipopeptaibols, a novel family of membrane active, antimicrobial peptides. Cell. Mol. Life Sci. 2001 58 1179-1188. 

In selecting a suitable chelating agent, its compatibility with the active drug should be considered. The addition of EDTA to thiomerosal solutions was suggested as a means of removing this most active antimicrobial compound from a solution by chelation (6). EDTA has been reported to enhance the photostability of solutions of minoxidil (48), riboflavin (69), sodium nitroprusside (83), tetracycline hydrochloride (71), demeclocycline hydrochloride (82), reserpine (106), and... 

Antimicrobial activity, within a pharmaceutical context, is generally found only in the organic acids. These are weak acids and will therefore dissociate incompletely to give the three entities HA, H+ and A- in solution. As the undissociated form, HA, is the active antimicrobial agent, the ionization constant, Ka, is important and the pKa of the acid must be considered, especially in formulation of the agent. 

Membrane-active antimicrobial peptides (AMPs), or host-defense peptides, kill microorganisms by permeabilizing their membrane. They often form amphipathic structures upon binding to lipid membranes. At low peptide concentrations they are normally in a monomeric surface-bound S-state, and at higher concentrations they may self-assemble and insert into the bilayer in a functionally active T- or I-state (see Figures 18.1 and 18.3). In our previous 19F NMR investigations we have compared three such AMPs, which are described below. 

---