Surfactants antimicrobial effects

Povidone-iodine (PVP-I, polyvinyl pyrrolidon-iodine complex, Betadine, Betaisodona, Braunol, Braunosan H, Disadine D.P., Disphex, Efo-Dine, Inadine, Isodine, Proviodine, Traumasept, Videne, CAS no. 25655-41-8). This is the most widely used iodophor and does not have the irritant properties associated with iodine solutions. At a strength of 7.5% in a surfactant base, povidone-iodine is applied as a surgical scrub, and at 4% is used as a shampoo or skin cleanser. Because of the small amounts of free iodine (less then 1 ppm in a 10% solution), antimicrobial effects are moderate in comparison with iodine solutions. 

Pulmonary surfactant, a complex mixture of phospholipids and proteins synthesized and secreted by alveolar type 11 cells, functions to keep alveoli from collapsing during expiration (55). Surfactant is composed of 90% to 95% lipids and 5 to 10% proteins including SP-A, -B, -C, and -D (5,56,57). All four of the SP accumulate within the alveolar spaces in PAP (57). The two hydrophilic SP, A and D, have been the most studied. SP-A and SP-D belong to the coUectin family and play roles in the innate immunity of the lung (55). Pulmonary collectins have antimicrobial effects and display both inflammatory and anti-inflammatory properties (55). In iPAP, AMs exhibit defective clearance of surfactant however. 

SLS s foaming properties do have a use in dental care besides consumer satisfaction, although its performance does not rely upon it heavily. The foaming action allows the polishing agent in toothpaste to be suspended and the detergency properties to reach otherwise inaccessible areas and cavities in the mouth. SLS also shows antimicrobial effects on bacterial flora in the mouth and hence is the most commonly chosen surfactant for toothpastes. 

Xia, et al. [49] studied a series of a-amino-(Ai-acyl)-fl-alkoxypropionate surfactants and found a correlation between their CMC and MIC values. However, the antimicrobial effect took place at concentrations of surfactant below the CMC. This suggests, in a good agreement with our results, that the antimicrobial activity is due to the individual molecules and not to the aggregates. 

Thus the antimicrobial effectiveness of the range of substances presented in Fig. 7.38a and b at a range of surfactant concentration will not be a simple function. The inactivation that occurs is frequently preceded at lower concentrations by an enhancement of activity. This is brought out well in Fig. 7.38a and b. 

Abbreviations of prominent use properties of the various classes of commercial surfactants are shown in Table 1. Antimicrobial activity includes germicidal, bactericidal, and bacteriostatic effects emolliency describes lubrication or a soft feel imparted to skin by surfactants a hair conditioner is a substantive surfactant appHed from aqueous solution to impart a lubricating or antistatic effect and opacifters are used to thicken hand-dishwashing products and cosmetic preparations to convey an appearance of high concentration and to retard solvent drainage from foam. 

Figure 4 Stabilized bromine antimicrobials are produced by eosinophils, a type of mammalian white blood cell. Bacteria are captured by phagocytosis and contained intracellularly within vesicles called phagosomes. Granules release cationic surfactants, lytic enzymes, and eosinophil peroxidase into the phagosome in a process known as degranulation. Eosinophil peroxidase, an enzyme that is structurally similar to the bromoperoxidases found in seaweed (Figure I), selectively catalyzes oxidation of bromide to hypobromite by reducing hydrogen peroxide to water. The hypobromite immediately reacts with nitrogenous stabilizers such as aminoethanesulfonic acid (taurine) to form more effective and less toxic antimicrobial agents.

Quaternary ammonium salts are well-known cationic surfactants and popular phase-transfer (FT) catalysts. In addition, these salts exhibit both antimicrobial activities and antielectrostatic effects. Another useful compound which belongs to the ammonium salt group is chinoline chloride, also known as vitamin B4 it is an essential component that ensures proper functioning of the nervous system and is widely used as a feed additive for livestock. 

The quaternary surfactants benzalkonium chloride (BAG) and benzethonium chloride are preferred by many manu-fecturers because of their stabihty, excellent antimicrobial properties in acid formulation, and long shelf life. They exhibit toxic effects on both the tear film and the corneal epithelium and have long been known to increase drug penetration. The toxicity of these compounds may be increased by the degree of acidity of the formulation. 

Several factors may influence the success or failure of a preservative to protect a formulation against microbial contamination. These factors include the interaction of the preservative with surfactants, active substances, other components of the vehicle, sorption by the polymeric packaging materials, and product storage temperature. Although hundreds of chemicals can fimction as germicides, only a few substances have made it to the marketplace. The small list is not based as much on a compound s effectiveness as an antimicrobial agent as on the compound s safety and effectiveness in the final product. 

Chlorocresol is used as an antimicrobial preservative in cosmetics and pharmaceutical formulations. It is generally used in concentrations up to 0.2% in a variety of preparations except those intended for oral administration or that contact mucous membrane. Chlorocresol is effective against bacteria, spores, molds, and yeasts it is most active in acidic media. Preservative efficacy may be reduced in the presence of some other excipients, particularly nonionic surfactants, see Sections 10 and 12. 

Kump TRR, Wan LSC, Chan LW. Effect of surfactants on the antimicrobial activity of preservatives. Pharma Acta Helv 1991 66 274-280. 

Sorbic acid is an antimicrobial preservative with antibacterial and antifungal properties used in pharmaceuticals, foods, enteral preparations, and cosmetics. Generally, it is used at concentrations of 0.05-0.2% in oral and topical pharmaceutical formulations, especially those containing nonionic surfactants. Sorbic acid is also used with proteins, enzymes, gelatin, and vegetable gums. It has been shown to be an effective preservative for promethazine hydrochloride solutions in a concentration of 1 g/L. ... 

The presence of peptides can also have an effect on wine quality. In general, these compounds are known to have several biological (antioxidant, antimicrobial, antihypertensive, etc.) and chemical-physical (surfactant) properties and also to affect the taste of some foods. However, peptides have received only a little attention, mainly because of the difficulties in their isolation from wines (Moreno-Arribas et al., 2002). 

Many pharmaceutical emulsifiers are GRAS in food applications. For example, a combination of lactic acid and propylene glycol used on broiler carcasses has been found highly effective in eliminating any salmonel-lae present. The surfactant 12-butyryloxy-9-octadecenoic acid (BOA) is composed of citric acid, EDTA, and sodium lauryl sulfate, and 0.6% of this medium has been found to reduce levels of S. typhimurium cells by >5 log10. Sodium lauryl sulfate resulted in the greatest increase in activity. The addition of ethanol, DMSO, or Span 20 to acids had little or no effect on their antimicrobial activity. In some cases it actually resulted in decreased activity of the acid (Tamblyn and Conner, 1997). 

U.S. 5753600 (1998) Kamegai et al. (Kao) Saccharide nonionic surfactant Low irritation to skin and scalp improve scalp/skin resistance to external stimuli like antimicrobial contagion improved antibacterial effect... 

---