Essential antimicrobial activity

Lis-BALCHIN M, HART s, SIMPSON E (2001) Buchu (Aguthosmu betuUna and. crenulata, Rutaceae) essential oils their pharmacological action on guinea-pig ileum and antimicrobial activity on microorganisms. J Pharm Pharmacol. S3 579-82. 

Cold-pressed essential oils from the peel are some of the most important by-products recovered during the processing of Citrus fruits. The presence of limonene in the aqueous discharges, with its antimicrobial activity [1], decreases the effectiveness of the waste treatment system and increases the time necessary for the biological breakdown of the organic matter produced in the peel oil recovery system [2,3]. Additional recovery of essential oils from waste water would increase industry s returns and reduce the pollution problems associated with the disposal of waste water [4,5]. Several methods for reducing the levels of residual essential oils in the aqueous effluent have been developed over the years [6-11]. 

Additional hypotheses for their mechanism of action have more recently been proposed. It is well known that proanthocyanidins are able to complex metals through their ortho-diphenol groups. This property is often viewed as imparting negative traits (e.g., reduction of the bioavailability of essential mineral micronutrients, especially iron and zinc) [87]. Since iron depletion causes severe limitation to microbial growth, their ability to bind iron has been suggested as one of the possible mechanisms explaining the antimicrobial activity of proanthocyanidins [88] (Table 1). 

Figure 15 Structures of lantibiotics containing a conserved methyllanthionine ring displayed in red. The glutamate that is essential for both mersacidin and haloduracin antimicrobial activity is shown in blue. The structure of plantaricin C has not yet been unambiguously determined and the proposed structure is shown. The stereochemistry of the lanthionine between residues 7 and 27 is not known.

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. 

In addition, the solubility of many preservatives in a mostly aqueous system may not be high enough for effective antimicrobial activity. For example, the para-bens often require heating in order to be solubilized. Additionally, it is essential to understand that bacteriostatic agents can partition between organic and aqueous phases in such a way that their activity is significantly reduced. Methyl paraben... 

Biond, D., Ciand, P., Geraci, C. Antimicrobial activity and chemical composition of essential oil from Sicilian aromatic plants. Flavor Fragrance 1993 8 331-337. 

The antimicrobial activity of eugenol may be associated with structural damage and alteration of the permeability mechanism of microsome, lysosome, and cell walls. The substance acts primarily on cytoplasm membranes, causing alteration of its permeability, and thus allowing leakage of essential bacterial cell constituents with subsequent death of the bacteria. 

Secondary metabolites include essential oils, used in the flavour and fragrance industries. Essential oils are found in over 50 plant families and represent terpenoids and other aromatic compounds accumulating typically at relatively low concentrations (usually <1% of fresh weight, but can be up to 20%), but which have useful antimicrobial activity (Biavati el a/., 2003). Production of essential oils by plants is affected by many factors influencing plant growth. 

Biological functions. The potential biological role of LF has been studied extensively over the last 30 years. Originally, the function of LF was considered essentially antimicrobial, but later, this glycoprotein has proven to be far more multifunctional. At present, the major known or speculated in vivo activities of LF may be summarised as follows (Hambraeus and Lonnerdal, 1994 Hutchens et al., 1994 Nuijens et al., 1996 Spik et al, 1998 Baveye etal., 1999) ... 

Clove bud oil has various biological activities such as antibacterial, antifungal, antioxidant and insecticidal properties. The high level of eugenol present in the essential oil imparts strong biological and antimicrobial activity. 

Clove exhibits potent antimicrobial activity against Bacillus subtilis, Escherichia coli and Saccharomyces cerevisiae (De et al., 1999). Essential oils from clove and eugenol show various degrees of inhibition against... 

Lopez, P., Sanchez, C., Batle, B. and Nerin, C. (2005) Solid and vapour phase antimicrobial activities of six essential oils susceptibility of selected foodborne bacterial and fungal strains. Journal of Agriculture and Food Chemistry 53, 6338-6346. 

Meena, M.R. and Sethi, V. (1 994) Antimicrobial activity of essential oils from spices. Journal of Food Science and Technology 31 (1), 68-70. 

Elgayyar, M., Draughon, F.A., Golden, D.A. and Mount, J.R. (2001) Antimicrobial activity of essential oils from plants against selected pathogenic and saprophytic microorganisms. Journal of Food Protection 64(7), 1019-1 024. 

The essential oil of cumin exhibits strong antimicrobial activity against Escherichia coli, Staphylococcus aureus and Listeria monocytogenes. Complete death time on exposure to cumin oil was 20, 180 and 90 min for E. coli, S. aureus and L. monocytogenes, respectively (Gachkar et al., 2007). 

Among the 60 constituents of the cumin oil identified by GC, GC-MS and olfactometry as essential volatiles, cuminaldehyde (36%), /3-pinene (19.3%), p-cymene (18.4%) and y-terpinene (15.3%) are the principal components showing high antimicrobial activity against the mould A. niger, the Gram-positive bacteria, Bacillus subtilis and S. epidermidis, as well as the yeasts, Saccharomyces cerevisiae and Candida albicans (Jirovetz et al., 2005). 

Jirovetz, L., Buchbauer, G., Stoyanova, A.S., Georgiev, E.V. and Damianova, S.T. (2005) Composition, quality control and antimicrobial activity of the essential oil of cumin (Cuminum cyminum F.) seeds from Bulgaria that had been stored for up to 36 years. Flavour and Fragrance journal 21 (1), 186-1 91. 

Bouzouita, N., Kachouri, F., Hamdi, M. and Chaabouni, M.M. (2003) Antimicrobial activity of essential oils from Tunisian aromatic plants. Flavour and Fragrance journal 18(5), 380-383. 

A long-lasting open question in the study of Actinomycetes is why this group of bacteria produce such highly diverged compounds as secondary metabolites. It is well known that some of the compounds exhibit antimicrobial activities, which leads to a plausible argument that the defensive function of these compounds is essential for the life of this kind of bacteria in the natural environment, although this simple idea does not fully explain the marked diversity of structure and activity of the secondary metabolites. 

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