Differently substituted flavanones were isolated from Leguminosae and their antibacterial activity was comparatively studied against methicillin-resistant Staphylococcus aureus (MRSA). The minimum inhibitory concentrations (MICs) of phytochemical flavanones to clinical isolates of MRSA were determined by a serial agar dilution method. The structure-activity relationship has indicated that 2',4'- or 2',6'-dihydroxylation of the B ring and 5,7-dihydroxylation of the A ring in the flavanone structure are important for significant anti-MRSA activity and that substitution with a certain aliphatic group at the 6- or 8-position also enhances the activity. Among the thirteen flavanones tested, tetrahydroxyflavanones with these structural characteristics isolated from Sophora exigua and Echinosophora koreensis showed intensive activity to inhibit the growth of all MRSA strains at 3.13-6.25 micrograms/ml. The present hydroxyflavanones would be useful in the phytotherapeutic strategy against MRSA infections.

Comparative Study on the Antibacterial Activity of Phytochemical Flavanones against Methicillin-resistant Staphylococcus aureus.

Myricetin is a common plant-derived flavonoid and is well recognised for its nutraceuticals value. It is one of the key ingredients of various foods and beverages. The compound exhibits a wide range of activities that include strong anti-oxidant, anticancer, antidiabetic and anti-inflammatory activities. It displays several activities that are related to the central nervous system and numerous studies have suggested that the compound may be beneficial to protect against diseases such as Parkinson’s and Alzheimer’s. The use of myricetin as a preserving agent to extend the shelf life of foods containing oils and fats is attributed to the compound’s ability to protect lipids against oxidation. A detailed search of existing literature revealed that there is currently no comprehensive review available on this important molecule. Hence, the present work includes the history, synthesis, pharmaceutical applications and toxicity studies of myricetin. This report also highlights structure-activity relationships and mechanisms of action for various biological activities.

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Myricetin: A Dietary Molecule with Diverse Biological Activities

Microbial Pathogens and Strategies for Combating them: Science, Technology and Education

The antimicrobial activity of essential oils is discussed in this review taking in account studies which were published in the period of time from 2008 until September 2010. Furthermore, the most important methods to examine the antimicrobial efficiency of essential oils are presented. The studies are divided into the following two groups, namely antibacterial and antifungal active agents depending on the activity of the applied essential oil against the test microorganisms. Various interesting possible applications are revealed such as the use of essential oils instead of synthetic drugs to circumvent the increasing resistance of some pathogens. Moreover, they could not only be used for the therapy of infectious illnesses, but also as preservatives in the food industry. A further possibility is, among others, the application of essential oils in skin products in order to treat or avoid dermal infections. Additionally, the prevalent constituents of the individual antimicrobial active essential oils are elaborated. Copyright © 2011 John Wiley & Sons, Ltd.

A review on recent research results (2008–2010) on essential oils as antimicrobials and antifungals. A review.

Natural products – antifungal agents derived from plants

Chemical composition and antimicrobial activity of volatile components from capitula and aerial parts of Rhaponticum acaule DC growing wild in Tunisia.

In vitro evaluation of antimicrobial and antioxidant activities of some Tunisian vegetables

Antimicrobial activity of methanolic extracts obtained from the aerial parts of Evax pygmaea was tested against five bacteria and two strains of phytopathogenic fungi using the agar diffusion and broth microdilution methods. Antioxidant properties were evaluated through the ability of the different fractions to scavenge the stable ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) and DPPH (1,1-diphenyl-2-picrylhydrazyl) radicals. The TEAC (Trolox Equivalent Antioxidant Capacity) and IC50 values of the fractions were calculated and compared. The experimental data indicated that all fractions exhibit moderate to appreciable antibacterial activities against all Gram-positive cocci and Gram-negative rods except Pseudomonas aeruginosa, but no antifungal activity was observed. Ethyl acetate and methanol fractions were found to cause significant free radical-scavenging effects in both assays. These results may suggest that E. pygmaea could be used as a natural preservative ingredient in the food and/or pharmaceutical industries.

Antimicrobial and antioxidant activities of methanol extracts of Evax pygmaea (Asteraceae) growing wild in Tunisia

Antioxidant, antibacterial, and antiviral effects of Lactuca sativa extracts

Chromatographic separation of Rhus tripartitum (Anacardiaceae) chemical components revealed the presence of four main natural substances: a new biflavonoid masazinoflavanone (S1), myricetin (S2), (-)-lyoniresinol 3α-O-β-D-glucopyranoside (S3), and (-)-methyl shikimate (S4). The anti-inflammatory activity of the new biflavonoid substance was performed. Compared with the standard drug dexamethasone, the biflavonoid substance masazinoflavanone (S1) inhibited in a dose-related manner carrageenan-induced paw edema in rats. Antiradical scavenging capacities of extracts and natural substances issued from Rhus tripartitum were tested using free radical forms of ABTS and DPPH. The Trolox Equivalent Antioxidant Capacity (TEAC) assay shows values of 1.92, 1.39, 1.25, 2.40, and 1.58 mM Trolox/mg sample respectively for the chloroformic extract, the ethyl acetate extract, (S1), (S2), and (S3). Values revealed form the total phenolic content assay were 299.3, 372.3, 99.1, and 235.7 mg Catechin/g extract respectively for the chloroformic, ethyl acetate, ethyl acetate/methanol, and methanolic extracts.

Samia Ammar

Papers

Chemical composition and antimicrobial activity of volatile components from capitula and aerial parts of Rhaponticum acaule DC growing wild in Tunisia.

In vitro evaluation of antimicrobial and antioxidant activities of some Tunisian vegetables

Antimicrobial and antioxidant activities of methanol extracts of Evax pygmaea (Asteraceae) growing wild in Tunisia

Antioxidant, antibacterial, and antiviral effects of Lactuca sativa extracts

Anti-inflammatory and antioxidant activities of some extracts and pure natural products isolated from Rhus tripartitum (Ucria)