Antimicrobial activity in the body

Antimicrobial activities observed in this study might be due to the presence of flavonoid Compounds. Extracts of various medicinal plants containing phenolic and flavonoids possess antimicrobial activity investigated the properties of Gallic, caffeic, vanillic acid, rutin, and quercetin of different wine against pathogenic microorganisms. (Higdon et al., 1996). Escherichia coli were the most sensitive bacterium and Flavo bacterium sp. was resistant against all phenolic compounds tested. The flavonoid revealed the presence of kaempferol, myricetin, naringin, quercetin and rutin in P. macrocarpa fruit. .(cook et al.,1996). The presence of these compounds might contribute to antimicrobial activity of P. macrocarpa fruit since Cushnieand Lamb reported that kaempferol, myricetin, naringin, quercetin and rutin have antimicrobial activity against human pathogenic microorganisms with some mechanisms of action such as inhibition Of nucleic acid synthesis, cytoplasmic membrane function and energy metabolisms.

Inflammation is a normal biological process in response to tissue injury, microbial pathogen infection, and chemical irritation. Inflammation is started by transfer of immune cells from blood vessels and release of mediators at the site of injury (Neussely et al.,2000). This process is followed by call of inflammatory cells, release of ROS, RNS, and inflammatory cytokines to release foreign pathogens, and repairing injured tissues. In general, normal inflammation is rapid and self-limiting, but normal type resolution and very long inflammation cause many lethal defects. Introdution of antimicrobials has long paved the way for human health. However, future effectiveness of antibiotics is somewhat doubtful, because microorganisms are developing potential in an unavoidable manner to these antimicrobial agents.

Flavonoids are known to be produce by plants in response to microbial infection; thus, it should not be surprising that they have been found in vitro to be effective antimicrobial substances against a wide range of microorganisms. Flavonoid rich plant extracts from different species have been reported to possess antibacterial activity.(Iqbal et al.,(2003) Several flavonoids including apigenin, galangin, flavone and flavonols glycosides, isoflavones, flavanones, and Chalcones have been shown to possess potent antibacterial activity Antibacterial flavonoids might be having various cellular targets, rather than one specific site of action.(Ohsugi et al.,1985) One of their molecular actions is to form complex with proteins through hydrogen bonding and hydrophobic effects, as well as by covalent bond formation. Thus, their mode of antimicrobial action may be related to their ability to inactivate microbial adhesins, enzymes, cell envelope transport proteins, and so forth. (Dixon et al (1983). Lipophilic flavonoids may also disrupt microbial membranes. Catechins, the most reduced form of the C3 unit in flavonoid compounds, have been extensively researched due to their antimicrobial activity. These compounds are reported for their in vitro antibacterial activity against Vibrio cholerae, Streptococcus mutans, Shigella, and other bacteria.

Flavonoids are present in photosynthesising cells and are commonly found in fruit, vegetables, nuts, seeds, stems, flowers, tea, wine, propolis and honey. For centuries, preparations having these compounds as the principal physiologically active constituents have been used to treat human diseases. (Berrel et al (1999) Increasingly, this class of natural products is becoming the subject of anti-infective research, and many groups have separated and identified the structures of flavonoids having antifungal, antiviral and antibacterial activity.(Bolwel et al.,(1995). Moreover, several groups have demonstrated synergy between active flavonoids as well as between flavonoids and existing chemotherapeutics. Reports of activity in the field of antibacterial flavonoid research having widely clash, probably owing to inter- and intra-assay variation in susceptibility testing (simmonds et al.,2003) However, several high-quality investigations have observe the relationship between flavonoid structure and antibacterial activity and these are in close agreement. In addition, numerous research groups have sought to clear the antibacterial mechanisms of action of selected flavonoids. (cotelle et al.,(1996) The activity of quercetin, for example, has been at least partially attributed to inhibition of DNA gyrase. It has also been proposed that sophora flavone G and (-)-epigallocatechin gallate inhibit cytoplasmic membrane function, and that licochalcones A and C inhibit energy metabolism.(Abrosca et al.,(1988) Other flavonoids whose mechanisms of action have been investigated include robinetin, myricetin, apigenin, rutin, galangin, 2,4,2′-trihydroxy-5′-methylchalcone and lonchocarpol A. These compounds represent novel leads, and future studies may allow the development of a pharmacologically acceptable antimicrobial agent or class of agents.

Natural products of higher plants may contain a new source of antimicrobial agents with possibly novel mechanisms of action. They are effective in the treatment of infectious diseases while simultaneously contain many of the side effects that are often associated with conventional antimicrobials. (Stewart et al.,(2000) A method using scanning electron microscope (SEM) to study the morphology of the bacterial and fungal microbes and thus determining antimicrobial activity.

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