Bio fabrication of silver nanoparticles with antibacterial and cytotoxic abilities using lichens.

Recently, increase bacterial resistance to antimicrobial compounds issue constitutes a real threat to human health. One of the useful materials for bacterial control is Silver nanoparticles (AgNPs). Researchers tend to use biogenic agents to synthesize stable and safe AgNPs. The principal aim of this study was to investigate the ability of lichen in AgNPs formation and to find out their suppression ability to MDR bacteria as well as their cytotoxic activity. In the current study, lichens (Xanthoria parietina, Flavopunctelia flaventior) were collected from the south of the Kingdom of Saudi Arabia. Lichens methanolic extracts were used for conversion of Ag ions to AgNPs. Prepared biogenic AgNPs were characterized by Ultraviolet-Visible (UV-Vis) Spectroscopy, Transmission electron microscopy (TEM), Dynamic Light Scattering (DLS) and Zeta potential and Energy-Dispersive X-ray Spectroscopy (EDS). Lichens Secondary metabolites were determined by Fourier-Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS). The antibacterial activity and synergistic effect of AgNPs were evaluated against pathogenic bacteria, including gram-positive; Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococcus (VRE), and gram-negative; (Pseudomonas aeruginosa, Escherichia coli) as well as the reference strains (ATCC) using the agar disk diffusion method. Cytotoxic effect of biogenic AgNPs was tested against HCT 116 (Human Colorectal Cancer cell), MDA-MB-231 (Breast cancer cell), and FaDu (Pharynx cancer cell) by MTT test. TEM imaging showed well-dispersed spherical particles of 1-40 nm size as well as zeta size showed 69-145 nm. Furthermore, FTIR and GC-MS identified various lichen chemical molecules. On the other hand, the highest antibacterial activity of AgNPs was noticed against P. aeruginosa, followed by MRSA, VRE, and E. coli. AgNPs influence on gram-negative bacteria was greater than that on gram-positive bacteria and their synergistic effect with some antibiotics was noted against examined microbes. Moreover, higher cytotoxicity for biogenic AgNPs against FaDu and HCT 116 cell line in relation to MDA-MB-231 was noted. Given the current findings, the biogenic AgNPs mediated by lichens had positive antibacterial, synergistic and cytotoxic powers. Therefore, they might be considered as a promising candidate to combat the multi-drug resistance organisms and some cancer cells.

Isolation, identification and anti-candidal activity of filamentous fungi from Saudi Arabia soil.

Ten fungal strains; namely, Penicillium melinii, Petriella setifera, Aspergillus pseudo-niger, Alternaria chlamydospora, Pythium nayoroense, Phoma glomerata, Mucor ramosissimus, Mucor racemosus, Fusarium chlamydosporum and Rhizopus azygosporus were isolated from soil. The extra- and intra-cellular extracts of the fungal strains grown on malt extract and yeast-extract sucrose media were screened for their anticandidal activity against different clinically-isolated Candida species. Most of the fungal extracts showed activity against different Candida species. However, the fungal strains grew on malt extract showed greater activities than those grew on yeast extract sucrose media. The activity of the intracellular was higher than the extracellular metabolites. All fungal extracts (extra and intra) were similar in chemical constituent; they contained carbohydrates and/or glycosides, unsaturated sterols and/or triterpens, tannins and traces of coumarins. Alkaloids, flavonoids, saponins, anthraquinones and cardenolides were no detected. The intra-cellular extracts contained more compounds than the extra-cellular extracts.

Anticandidal Activity of Extracts and a Novel Compound, Amnomopin, Isolated From Petriella setifera.

A novel triterpenoidal compound named 'amnomopin' (3ß-diglucoside-5,12-28-oic acid), which is named IUPAC as 3-O-(2' âž” 1″diglucoside)1,2,3,4,4a,5,6,6a,6b,7,9,10,11,12,12a,12b,13,14b-octadecahydro-10-hydroxy-2,2,6a,6b,9,9,12a-heptamethylpicene-4a-carboxylic acid, was isolated from the extract Petriella setifera. The total alcoholic extract of P. setifera showed a great activity against clinically isolated Candida species, including Candida albicans, Candida dubliniensis, Candida famata, Candida glabrata, Candida inconspicua, Candida kefyr, Candida krusei, Candida norvegensis, Candida parapsilosis and Candida tropicalis. Also, the new compound amnomopin was active against all the investigated Candida species. The highest anticandidal activity of P. setifera extract was obtained against C. kefyr (22.6 ± 1.5 mm), C. albicans and C. norvegensis (21.3 ± 0.63 mm) and C. krusei (20.6 ± 1.5 mm). Moreover, the minimum inhibitory concentrations of both the total extract and the isolated compound were low. The minimum inhibitory concentration of the compound isolated from P. setifera was 0.49 µg/mL against C. kefyr, 0.98 µg/mL against C. albicans and C. norvegensis and 1.95 µg/mL against C. krusei. The oral dosing of the extract and the isolated compound did not show any significant effect on the activity of alanine aminotransferase, aspirate aminotransferase and the levels of blood urea and serum creatinine. Copyright © 2017 John Wiley & Sons, Ltd.

Amhezole, A Novel Fungal Secondary Metabolite from Aspergillus terreus for Treatment of Microbial Mouth Infection.

Bio-guided fractionation of Aspergillus terreus extract leads to isolation of a novel terpenoidal secondary metabolite. The isolated compound and the total alcoholic extract of Aspergillus terreus showed a remarkable activity against microbial mouth infections; namely, Candida albicans, Lactobacillus acidophilus, Streptococcus gordonii, and S. mutan. Moreover, the Minimum Inhibitory Concentration of the isolated compound was determined and showed low values. The combination of each of the alcoholic extract of A. terreus and the isolated compound Coe-Comfort tissue conditioner inhibited the growth of Candida albicans at concentrations of 500 and 7.81 µg/mL, respectively, Lactobacillus acidophilus at concentrations of 250 and 7.81 µg/mL, respectively, Streptococcus gordonii at concentrations of 1000 and 62.50 µg/mL, respectively, and S. mutans at concentrations of 1000 and 125 µg/mL, respectively. The oral dosing of the extract and the isolated compound did not show any significant effect on the activity of alanine aminotransferase, aspirate aminotransferase, and the levels of blood urea and serum creatinine. Copyright © 2017 John Wiley & Sons, Ltd.