Felicia Diodata D'Auria

1-[(3-Aryloxy-3-aryl)propyl]-1H-imidazoles, New Imidazoles with Potent Activity against Candida albicans and Dermatophytes. Synthesis, Structure−Activity Relationship, and Molecular Modeling Studies

New 1-[(3-aryloxy-3-aryl)propyl]-1 H-imidazoles were synthesized and evaluated against Candida albicans and dermatophytes in order to develop structure-activity relationships (SARs). Against C. albicans the new imidazoles showed minimal inhibitory concentrations (MICs) comparable to those of ketoconazole, miconazole, and econazole, and were more potent than fluconazole. Several derivatives ( 10, 12, 14, 18- 20, 24, 28, 29, 30, and 34) turned out to be potent inhibitors of C. albicans strains resistant to fluconazole, with MIC values less than 10 microg/mL. Against dermatophytes strains, compounds 20, 25, and 33 (MIC <or= 5 microg/mL) were equipotent to ketoconazole, econazole, and miconazole. SARs of imidazoles 10- 44 were rationalized with reasonable accuracy by a previously developed quantitative pharmacophore for antifungal agents.

A three-step culture system to increase the xanthone production and antifungal activity of Hypericum perforatum subsp. angustifolium in vitro roots

Hypericum perforatum is a well-known medicinal plant. Among all secondary metabolites produced by this species, xanthones are very interesting for their antifungal activity. In the present study, with the aim to improve xanthone production and antifungal activity of H. perforatum subsp. angustifolium (sin. Fröhlich) Borkh in vitro roots, a new methodology consisting of a three-step culture system, has been developed. Regenerated roots of H. perforatum were cultured in a three-step culture system: in the first step, to increase biomass, the roots were cultured in half-strength liquid Murashige and Skoog (MS) medium supplemented with 1 mg L(-1) indole butyric acid (IBA) and 1.5% sucrose. In the second and third steps, to stimulate secondary metabolism, the roots were cultured with 1.1 mg L(-1) 2,4-dichlorophenoxyacetic acid (2,4-D), 0.215 mg L(-1) kinetin (KIN), and 0.186 mg L(-1) 1-naphthalenacetic acid (NAA). In the third step, some of the roots were treated with chitosan. Xanthone production increased 2.7 times following the three-step method. The mean minimal inhibitory concentration (MIC) values were of 36.9, 26.7, and 65 μg mL(-1), against Candida species, Cryptococcus neoformans and dermatophytes, respectively. A positive correlation between xanthone accumulation and antifungal activity has been shown.

Chemical composition and antifungal activity of Hypericum perforatum subsp. angustifolium roots from wild plants and plants grown under controlled conditions

The medicinal properties of the aerial parts of Hypericum perforatum subsp. angustifolium have been extensively investigated, yet little is known about the chemical composition or potential uses of the root extracts. In this study, xanthone production in wild plants and plants grown under controlled conditions was investigated. Chemical analyses carried out on wild plants revealed that xanthones were mainly accumulated in the roots. We mainly detected 1,7-dihydroxyxanthone, paxanthone, 5-O-methyl-2-deprenylrheediaxanthone B, kielcorin. The roots of wild plants showed low xanthone accumulation. In the roots of plants grown under controlled conditions, xanthone accumulation was 27 times greater than that in the roots of wild-grown plants. Kielcorin was not detected in the roots of plants grown under controlled conditions. As xanthones are known for their antifungal activity, the extracts from both samples were tested against the human fungal pathogens Candida albicans, non-albicansCandida species, Cryptococcus neoformans, and dermatophytes. The root extracts from plants grown under controlled conditions showed greater antifungal activity, probably correlated with higher xanthone accumulation.

In vitro antifungal activity of extracts obtained from Hypericum perforatum adventitious roots cultured in a mist bioreactor against planktonic cells and biofilm of Malassezia furfur

Xanthone-rich extracts from Hypericum perforatum root cultures grown in a Mist Bioreactor as antifungal agents against Malassezia furfur. Extracts of Hypericum perforatum roots grown in a bioreactor showed activity against planktonic cells and biofilm of Malassezia furfur. Dried biomass, obtained from roots grown under controlled conditions in a ROOTec mist bioreactor, has been extracted with solvents of increasing polarity (i.e. chloroform, ethyl acetate and methanol). The methanolic fraction was the richest in xanthones (2.86 ± 0.43 mg g− 1 DW) as revealed by HPLC. The minimal inhibitory concentration of the methanol extract against M. furfur planktonic cells was 16 μg mL− 1. The inhibition percentage of biofilm formation, at a concentration of 16 μg mL− 1, ranged from 14% to 39%. The results show that H. perforatum root extracts could be used as new antifungal agents in the treatment of Malassezia infections.

Evaluation of Anti-Candida Activity of Vitis vinifera L. Seed Extracts Obtained from Wine and Table Cultivars

For the first time, grape seed extracts (GSEs), obtained from wine and table cultivars of Vitis vinifera L., cultured in experimental fields of Lazio and Puglia regions of Italy and grown in different agronomic conditions, have been tested on 43 Candida species strains. We demonstrated a significant correlation between the content of the flavan-3-ols in GSEs extracts, with a polymerization degree ≥4, and anti-Candida activity. Moreover, we demonstrated that GSEs, obtained from plants cultured with reduced irrigation, showed a content of polymeric flavan-3-ols >250 mg/g with geometric mean MIC values between 5.7 and 20.2 mg/L against Candida albicans reference strains. GSE, showing 573 mg/g of polymeric flavan-3-ols, has been tested in an experimental murine model of vaginal candidiasis by using noninvasive in vivo imaging technique. The results pointed out a significant inhibition of Candida albicans load 5 days after challenge. These findings indicate that GSEs with high content of polymeric flavan-3-ols can be used in mucosal infection as vaginal candidiasis.

Synthesis of cyclic imides (methylphtalimides, carboxylic acid phtalimides and itaconimides) and evaluation of their antifungal potential.

BACKGROUND This paper describes the synthesis of three different subfamilies of cyclic imides: methylphtalimides, carboxyl acid phtalimides and itaconimides. METHODS Fifteen compounds (five of each sub-family) were obtained by the reaction of appropriated anhydrides and different aromatic amines, using the manual Topliss method. Their structures were confirmed by spectral data (IR and NMR). The antifungal activity of the synthesized compounds was investigated by broth microdilution to determine the minimal inhibitory concentration (MIC). The ability to inhibit the biofilm formation or destroy mature Candida albicans biofilm was also evaluated for the most active substances. RESULTS The results indicated that only the itaconimides 11-15 exhibited potent and promising antifungal properties, with MIC100 between 1 and 64 μg mL-1, being several times more potent than the reference drug, Fluconazole. Compounds 11-15 inhibited between 64% and 95% of biofilm formation, and destroyed between 78% and 99% of mature biofilm at a concentration of 64 μg mL-1. ADME (absorption, distribution, metabolism and excretion) in silico evaluations were carried out to predict whether the molecules under study are good drug candidates. CONCLUSIONS Itaconimides appear to be promising and relevant as tools for the future development of new and effective medicinal agents to treat fungal diseases.

Anti‐Dermatophyte and Anti‐Malassezia Activity of Extracts Rich in Polymeric Flavan‐3‐ols Obtained from Vitis vinifera Seeds

Several human skin diseases are associated with fungi as dermatophytes and Malassezia. Skin mycoses are increasing and new alternatives to conventional treatments with improved efficacy and/or safety profiles are desirable. For the first time, the anti‐dermatophytes and the anti‐Malassezia activities of Vitis vinifera seed extracts obtained from different table and wine cultivars have been evaluated. Geometric minimal inhibitory concentration ranged from 20 to 97 µg/mL for dermatophytes and from 32 to 161 µg/mL for Malassezia furfur. Dried grape seed extracts analyzed by HPLC/DAD/ESI/MS showed different quali–quantitative compositions in terms of monomeric and polymeric flavan‐3‐ols. The minimal inhibitory concentrations for Trichophyton mentagrophytes and for M. furfur were inversely correlated with the amount of the polymeric fraction (r = −0.7639 and r = −0.7228, respectively). Differently, the antifungal activity against T. mentagrophytes was not correlated to the content of flavan‐3‐ol monomers (r = 0.2920) and only weakly correlated for M. furfur (r = −0.53604). These results suggest that extracts rich in polymeric flavan‐3‐ols, recovered from V.  vinifera seeds, could be used for the treatment of skin fungal infections. Copyright

Efficient Electrochemical N-Alkylation of N-Boc-Protected 4-Aminopyridines: Towards New Biologically Active Compounds

The use of electrogenerated acetonitrile anion allows the alkylation of N-Boc-4-aminopyridine in very high yields, under mild conditions and without by-products. The high reactivity of this base is due to its large tetraethylammonium counterion, which leaves the acetonitrile anion “naked.” The deprotection of the obtained compounds led to high yields in N-alkylated 4-aminopyridines. Nonsymmetrically dialkylated 4-aminopyridines were obtained by subsequent reaction of monoalkylated ones with t-BuOK and alkyl halides, while symmetrically dialkylated 4-aminopyridines were obtained by direct reaction of 4-aminopyridine with an excess of t-BuOK and alkyl halides. Some mono- and dialkyl-4-aminopyridines were selected to evaluate antifungal and antiprotozoal activity; the dialkylated 4-aminopyridines 3ac, 3ae and 3ff showed antifungal towards Cryptococcus neoformans; whereas 3cc, 3ee and 3ff showed antiprotozoal activity towards Leishmania infantum and Plasmodium falciparum.