Antifungal photosensitive activity of Porophyllum obscurum (Spreng.) DC.: Correlation of the chemical composition of the hexane extract with the bioactivity.

We report Porophyllum obscurum as a source of new photosensitizers with potential use in Photodynamic Therapy as an alternative for oropharyngeal candidiasis treatment. The antifungal photosensitive activity of different extracts from P. obscurum was evaluated by using microdilution and bioautographic assays. The Minimum Fungicidal Concentration for hexanic extract under UV-A irradiation was 0.98µg/mL, but it was inactive in experiments without irradiation. The bioassay-guided fractionation of this extract led to the isolation of four thiophenes responsible for the photosensitive activity: 2,2':5'2″terthiophene, 5-(3-buten-1-ynyl)-2,2'-bithiophene, 5-(4-acetoxy-1-butenyl)-2,2'- bithiophene and 5-(4-hydroxy-1-butenyl)-2,2'- bithiophene, with Minimum Fungicidal Concentrations ranging 0.24-7.81µg/mL under UV-A irradiation. The activity of the hexanic extract was evaluated against 25 clinical strains of Candida spp. isolates as etiological agents of oropharyngeal candidiasis. No differences in susceptibility were observed in strains resistant and susceptible to conventional antifungal drugs. Qualitative and quantitative chemical analyses of seven samples of P. obscurum collected in four different phenological stages were carried out showing that full flowering stage possesses the highest thiophenes content. These data also allowed us to establish a correlation between the thiophene composition of the different extracts and their antifungal photosensitive activity, according to a second order polynomial model with the equation: y=11.2603-0.6831*x+0.0108*x2. The thiophenes isolated were the responsible of antifungal photosensitive activity and can be used for the future standardization of the extract. Results showed that P. obscurum hexanic extract could be potentially developed as an Herbal Medicinal Product to be applied as a photosensitizer in Photodynamic Therapy.

Constituents of Flourensia blakeana (Asteraceae).

Chemical study of the aerial parts of Flourensia blakeana Dillon allowed the isolation and identification of two novel compounds, 3, 5, 5'-trihydroxy-7, 3'- dimethoxyflavanone (1), and 2α-angeloyloxycostic acid (2) together with several known compounds. The structures were elucidated using spectroscopic data from.ID, 2D NMR and HRDEIMS experiments.

6-Methoxyflavonoids and Other Constituents from Microliabum polymnioides (Asteraceae).

The flower heads of Microliabum polymnioides afforded scopoletin, 5,4'-dihydroxy-3,6,7-trimethoxyflavone, 3,5,4'-trihydroxy-6,7-dimethoxyflavone and 3,5,7,4'-tetrahydroxy-6-methoxyflavone. The leaves contained hexadecanoic acid, phytol and docosane. This is the first report on the presence of 6-methoxyflavonoids in Microliabum genus.

Chemical composition, antifungal and herbicidal effects of essential oil isolated from Chersodoma Argentina (Asteraceae).

Analysis of the hydrodistilled essential oil of the aerial parts of Chersodoma argentina Cabrera by GC-MS and NMR spectroscopy revealed that over 80% consisted of monoterpene hydrocarbons such as alpha-thujene, alpha-pinene and beta-pinene. Contact and headspace volatile exposure assays of the essential oil demonstrated antifungal activity against Sclerotinia sclerotiorum, Sclerotium rolfsii and Rhizoctonia solani with the contact assay showing greater activity than the headspace assay. Herbicidal activity was shown by reduced root growth of Allium porrum, Solanum lycopersicon and Sorghum halepense in both assays.

Antifungal activity of Heterothalamus alienus metabolites.

The chemical study of Heterothalamus alienus gave rutin, spathulenol (1), (1R,7S)-germacra-4(15),5,10(14)-trien-1beta-ol (2), sakuranetin (3), padmatin 3-acetate (4), (2R,3R)-dihydroquercetin-7,3',4'-trimethyl ether (5), (2R,3R)-dihydroquercetin-7,4'-dimethyl ether (6), (2R,3R)-3-acetoxy-5,7,4'-trihydroxyflavanone (7), as the main components of an antifungal extract of the aerial parts of the plant. Compound 2 showed moderate activity, with Epidermophyton floccosum being the most susceptible species (MIC = 100 microg/mL); compound 3 showed the best antifungal behavior having a broad spectrum of action and the lowest MICs. This flavanone along with flavanolol 5 showed very good activity against standardized (MIC = 31.2 microg/mL) as well as clinical isolates of Trichophyton rubrum and T. mentagrophytes (MIC ranges 31.2-62.5 microg/mL and 31.2-125 microg/mL, respectively) and demonstrated not only fungistatic but also fungicide properties. Flavanolol 6 was active against all the dermatophytes tested with MICs of 62.5-250 microg/mL. Rutin, spathulenol (1) and the 3-acetylated flavanones 4 and 7 were inactive or marginally active against the fungal panel.

Antioxidant and free radical scavenging activities of Misodendrum punctulatum, myzodendrone and structurally related phenols.

The peroxyl radical scavenging activity of a dry methanol extract of Misodendrum punctulatum was determined by means of luminol-enhanced chemiluminescence assay, allowing to calculate the total reactive antioxidant potential (TRAP) index equal to 239 +/- 26 microm, expressed in Trolox equivalents. The flavan-3-ol catechin (1) and the phenylbutanone derivative myzodendrone (2) were identified through assay-guided fractionation as active metabolites present in the extract, and their structures were elucidated by chemical and spectroscopic analysis. Three other structurally related synthetic phenols, dehydrozingerone (3), zingerone (4) and myzodendrone aglycone (5), were also analysed using this method. Compounds 1 and 2 were highly effective as free radical scavengers (TRAP = 1257 microm and 1018 microm, respectively) when compared with Trolox (TRAP = 144 microm), used as a standard. Compounds 3 and 5 were also active showing TRAP values of 229 microm and 219 microm, respectively, similarly to that observed for the dry extract. On the other hand, 4 was inactive. Catechin (1) also reduced the production of thiobarbituric acid reactive substances (TBARS) in rat liver homogenates, with IC50 = 26 microg/mL, superior to that obtained for Trolox, IC50 = 73 microg/mL. Compounds 2 and 5 showed IC50 values > 1000 microg/mL, while no activity could be observed for 3, 4, or the extract.