Synergism of CAY-1 with amphotericin B and itraconazole.

BACKGROUND: CAY-1 is a fungicidal saponin from cayenne pepper whose mode of action differs from amphotericin B (AB) and itraconazole (IT). This work determined CAY-1 synergism with AB or IT. METHODS: CAY-1 was purified and used in checkerboard microdilution studies where CAY-1 and AB or IT were mixed with nongerminated (NG) and germinating (G) conidia of three Aspergillus species and Candida albicans. Inhibition was visually determined at 24 and 48 h. RESULTS: CAY-1 had predominantly additive-synergistic interaction with AB or IT against the Aspergillus NG and G conidia. Excellent synergy between CAY-1 and AB occurred at 24 and 48 h against C. albicans. Results suggest CAY-1 enhances AB and IT efficacy.

CAY-1, a novel antifungal compound from cayenne pepper.

CAY-1, a novel saponin from Capsicum frutescens (commercially known as cayenne pepper) was investigated to determine its in vitro antifungal activity, mechanism of action and mammalian cell cytotoxicity. CAY-1 was active against 16 different fungal strains, including Candida spp. and Aspergillus fumigatus [minimum inhibitory concentrations (MIC) ranging from 4 to 16 microg ml(-1)], and was especially active against Cryptococcus neoformans (90% inhibition at 1 microg ml(-1)). Synergistic activity was also observed between CAY-1 and amphotericin B against Candida albicans and A. fumigatus. No significant cytotoxicity was demonstrated when CAY-1 was tested against 55 mammalian cell lines at up to 100 microg ml(-1). Importantly, CAY-1 appears to act by disrupting the membrane integrity of fungal cells.

CAY-I, a fungicidal saponin from Capsicum sp. fruit.

Saponins are steroidal or terpenoid-based glycosides with surface active properties. A steroidal saponin, CAY-1, with a molecular weight of 1243.35 Da, was isolated and purified to homogeneity from commercially available dry, ground fruit of Capsicum frutescens. CAY-1 was shown to be a potent fungicide for the germinating conidia of Aspergillus flavus, A. fumigatus, A. parasiticus and A. niger with species-dependent LD90 values between 3 and 20 microM. Activity against some Aspergillus species was affected by the test medium used. In vitro assays, CAY-1 was effective against Pneumocystis carinii (IC50): 9.5 microM) and Candida albicans (IC90: 6.2 microM). CAY-1 had no effect on the viability of the nongerminating conidia of the two filamentous fungi, P. carinii and C. albicans, nor on the conidial type of Fusarium oxysporum. It was ineffective against the bacteria Enterobacter agglomerans, Bacillus subtilis, Escherichia coli and Staphylococcus aureus. CAY-1 was not cytotoxic to A 549 lung carcinoma cells or HeLa cells at effective fungicidal concentrations. The results indicate that CAY-1 is an effective fungicide for Aspergillus species, C. albicans and P. carinii at concentrations below the threshold for mammalian cell toxicity.

Solid-phase microextraction for the detection of termite cuticular hydrocarbons.

Solid-phase microextraction (SPME)-gas chromatography-mass spectrometry was used to identify the cuticular hydrocarbons of the subterranean termite Coptotermes formosanus Shiraki. Headspace SPME and direct contact SPME methods were evaluated and compared to the hexane extraction method. Variables, such as temperature, time, number of termites, condition of the termites, and the type of SPME fiber were evaluated. Methods were refined to increase the reproducibility as well as the sensitivity. Both SPME methods were successfully used for the identification of all the major termite cuticular hydrocarbons. Using the headspace SPME method, other compounds of interest could also be identified, such as fatty acids. Using the direct contact SPME method, termites could be repeatedly studied over time to monitor chemical changes.

All-D-cecropin B: synthesis, conformation, lipopolysaccharide binding, and antibacterial activity.

Cecropin B (LCB) is a natural peptide with antibacterial and antifungal properties. The enantiomer of LCB, containing all-D amino acids (DCB), was synthesized to examine its antibacterial and binding properties. The conformation of DCB was compared to its enantiomer by circular dichroism. Both the L- and D-peptides showed an identical induction of alpha-helical secondary structure. However, binding studies between Lipopolysaccharide (LPS) and DCB or LCB were studied with a dimethylmethylene blue spectrophotometric assay, showing the two enantiomeric peptides differed in their interaction with LPS. Antibacterial activity of DCB was determined against three Gram-negative bacteria, Pantoea agglomerans (ATCC 27996), Escherichia coli (ATCC 8739), and Pseudomonas aeruginosa (ATCC 17648), giving comparable results to LCB.

D-cecropin B: proteolytic resistance, lethality for pathogenic fungi and binding properties.

L-Cecropin B (LCB) is a potent fungicidal peptide that is subject to proteolytic degradation by extracellular enzymes produced by Aspergillus flavus. We hypothesized that D-cecropin B (DCB), containing all D-amino acids, should resist proteolysis while retaining its fungicidal and target specificities. DCB was synthesized by solid phase methods using Fmoc chemistry. In vitro, at pH 6 x 0, DCB was lethal against the germinating conidia of A. flavus (LD90, 25 microM) and A. fumigatus (LD98, 25 microM) and for nongerminating and germinating conidia of Fusarium moniliforme (LD98, 1 x 25 microM) and F. oxysporum (LD95, 2 x 5 microM) at concentrations similar to those previously reported for LCB. It was lethal for Candida albicans with an LD98 at 12 x 5, microM. DCB was not active for the nongerminating conidia of A. fumigatus or A. flavus. Papain, trypsin, pepsin A and Staphylococcus aureus V8 protease degraded LCB but not DCB. Binding assays and circular dichroism showed DCB and LCB bound to cholesterol, ergosterol, beta-1,3-glucan, mannan and chitin. Data show that DCB retains the potent fungicidal properties of the L-form while being resistant to proteolytic enzymes that degrade the latter peptide. This study demonstrates that D-enantiomerization of cecropin B yields a novel fungicidal peptide, which resists proteolytic degradation and is lethal for pathogenic fungi.