There are concerns about using synthetic phenolic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) as food additives because of the reported negative effects on human health. Thus, a replacement of these synthetics by antioxidant extractions from various foods has been proposed. More than 8000 different phenolic compounds have been characterized; fruits and vegetables are the prime sources of natural antioxidants. In order to extract, measure, and identify bioactive compounds from a wide variety of fruits and vegetables, researchers use multiple techniques and methods. This review includes a brief description of a wide range of different assays. The antioxidant, antimicrobial, and anticancer properties of phenolic natural products from fruits and vegetables are also discussed.

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Phytochemicals: Extraction, Isolation, and Identification of Bioactive Compounds from Plant Extracts

The increasing incidence of drug-resistant pathogens has drawn the attention of the pharmaceutical and scientific communities towards studies on the potential antimicrobial activity of plant-derived substances, an untapped source of antimicrobial chemotypes, which are used in traditional medicine in different countries. The aim of this review is to provide recent insights regarding the possibilities of the most important natural antimicrobial compounds derived from plant sources containing a wide variety of secondary metabolites, which are useful as alternative strategies to control infectious diseases. This review will focus on natural plant products as a useful source of antimicrobial molecules, active in particular, on bacteria and fungi. When considering that many of these compounds, which have been used for centuries, are a source of new drugs and that there are ever-increasing technical breakthroughs, it can be envisaged that in the next years some different molecules discovered by ingenious screeni...

Plant-derived antimicrobial compounds: alternatives to antibiotics.

Despite improvement of antifungal therapies over the last 30 years, the phenomenon of antifungal resistance is still of major concern in clinical practice. In the last 10 years the molecular mechanisms underlying this phenomenon were extensively unraveled. In this paper, after a brief overview of currently available antifungals, molecular mechanisms of antifungal resistance will be detailed. It appears that major mechanisms of resistance are essential due to the deregulation of antifungal resistance effector genes. This deregulation is a consequence of point mutations occurring in transcriptional regulators of these effector genes. Resistance can also follow the emergence of point mutations directly in the genes coding antifungal targets. In addition we further describe new strategies currently undertaken to discover alternative therapy targets and antifungals. Identification of new antifungals is essentially achieved by the screening of natural or synthetic chemical compound collections. Discovery of new putative antifungal targets is performed through genome-wide approaches for a better understanding of the human pathogenic fungi biology.

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Antifungal resistance and new strategies to control fungal infections.

Bael (Aegle marmelos (L.) Corr.) is an important medicinal plant of India. Leaves, fruits, stem and roots of A. marmelos have been used in ethno medicine to exploit its’ medicinal properties including astringent, antidiarrheal antidysenteric, demulcent, antipyretic and anti-inflammatory activities. Compounds purified from bael have been proven to be biologically active against several major diseases including cancer, diabetes and cardiovascular diseases. Preclinical studies indicate the therapeutic potential of crude extracts of A. marmelos in the treatment of many microbial diseases, diabetes and gastric ulcer. This review covers the biological activities of some isolated chemical constituents of A.marmelos and preclinical studies on some crude extracts and pure compounds to explore novel bioactive compounds for therapeutic application.

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Biological activities of crude extracts and chemical constituents of Bael, Aegle marmelos (L.) Corr. #

Medicinal property, phytochemistry and pharmacology of several Jatropha species (Euphorbiaceae): a review.

Natural products – antifungal agents derived from plants

The antimicrobial potential of seventy-seven extracts from twenty-four plants was screened against eight bacteria and four pathogenic fungi, using microbroth dilution assay. Lowest concentration of the extract, which inhibits any visual microbial growth after treatment with p-iodonitrotetrazolium violet, was considered to be minimum inhibitory concentration (MIC). Water extracts of Acacia nilotica, Justicia zelanica, Lantana camara and Saraca asoca exhibited good activity against all the bacteria tested and the MIC was recorded in range of 9.375-37.5 microg/ml and 75.0-300.0 microg/ml against the bacterial and fungal pathogens, respectively. The other extracts of Phyllanthus urinaria, Thevetia nerifolia, Jatropha gossypifolia Saraca asoca, Tamarindus indica, Aegle marmelos, Acacia nilotica, Chlorophytum borivilianum, Mangifera indica, Woodfordia fruticosa and Phyllanthus emblica showed antimicrobial activity in a range of 75-1200 microg/ml.

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Antimicrobial Activity Of Some Indian Medicinal Plants

Antimicrobial activities of 55 plant extracts were evaluated against twelve microbial strains using macrobroth dilution assay. Twenty one extracts exhibited antimicrobial activity against the tested microorganisms in range of 0.20 to 6.25 mg/ml. Extracts from Madhuca longifolia, Parkia biglandulosa, Pterospermum acerifolium showed highest antimicrobial potential among the tested plants (MIC 0.20-12.5 mg/ml). Bio-assays showed presence of multiple specifically active compounds at different R values in various f plant extracts. Acetone and ethanol extract of M. longifolia, P. biglandulosa; P. acerifolium shows greater antibacterial activity as compared to their water extracts and could be the potential source to develop new antimicrobial agents.

Screening of Some Selected Medicinal Plants Extracts for In-vitro Antimicrobial Activity

In vitro and in vivo antimicrobial activities of seeds of Caesalpinia bonduc (Lin.) Roxb.

The post-antifungal effect (PAFE) of the antifungal compound 2-(3,4-dimethyl-2,5-dihydro-1H-pyrrol-2-yl)-1-methylethyl pentanoate (DHP) upon Aspergillus fumigatus was investigated. The conidia of A. fumigatus were exposed to DHP at concentrations of 1 x and 4 x MIC(90) for variable times at 37 degrees C. Amphotericin B (AmB)-treated or drug-free controls were included in the study. DHP as well as AmB exposure resulted in prolonged lag phases of the turbidimetric growth curves. Both the treatments gave rise to delayed growth, with lag phases of 11 h upon treatment with a concentration of 4 x MIC(90) for 4 h. Furthermore, it was observed that DHP inhibited the expression of three A. fumigatus secretory proteins of 18, 42 and 55 kDa. One protein of 42 kDa was found to be a metalloprotease, which is an important virulence factor. Analysis of time-dependent antigenic profiles showed the early expression of high-molecular-mass antigens. Expression of low-molecular-mass antigens started after 24 h culture. The antigens of A. fumigatus that are expressed during the early phase of growth were observed to be adversely affected after treatment with DHP. Although the mechanism of action of DHP to inhibit these proteins/antigens is unknown, the observations may be valuable to understand their role in the virulence of the pathogen, as well as the antigen-mediated responses caused by A. fumigatus.

T. K. Mandal

Papers

Natural products – antifungal agents derived from plants

Antimicrobial Activity Of Some Indian Medicinal Plants

Screening of Some Selected Medicinal Plants Extracts for In-vitro Antimicrobial Activity

In vitro and in vivo antimicrobial activities of seeds of Caesalpinia bonduc (Lin.) Roxb.

Post-antifungal effects of the antifungal compound 2-(3,4-dimethyl-2,5-dihydro-1H-pyrrol-2-yl)-1-methylethyl pentanoate on Aspergillus fumigatus.