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.

/pdf/bio-fabrication-of-silver-nanoparticles-with-antibacterial-9q6js1ssdu.pdf

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

One-Pot Pseudo Five Component Synthesis of Biologically Relevant 1,2,6-Triaryl-4-arylamino-piperidine-3-ene-3- carboxylates: A Decade Update

Piperidine is a saturated heterocyclic ring, considered as a privileged scaffold in view of its role in wide range of biological activities. Piperidine is good candidate molecule for obtaining potent antioxidant agents. The planar nature of this heterocyclic nucleus allows the introduction of substituent groups at different positions on the ring. In the present review, the antioxidant profile of piperidine containing compounds has been focused. The compounds were classified into naturally occurring piperidines, unsaturated piperidines, N-substituted piperidines, piperamides, piperanols, piperidine oximes, and hydrazides.

/pdf/antioxidant-potential-of-piperidine-containing-compounds-a-2hngmkt0jr.pdf

Antioxidant potential of piperidine containing compounds-a short review

The new-fangled bis(4-substituted benzyl) 4-(4-substitued phenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate derivatives were synthesized by the union of substituted aryl aldehyde, tert-butyl acetoacetate, ammonium carbonate with 4-substituted benzyl alcohol via Hantzsch ester synthesis in aqueous medium under catalyst-free conditions. The newly synthesized compounds were characterized by spectroscopic techniques such as IR, NMR (1 H and 13 C), ESI mass, elemental analysis, and single-crystal X-ray diffraction. The characterized title compounds were evaluated for the larvicidal activity against Anopheles arabiensis by standard WHO larvicidal assay method using Temephos as standard at 4 μg/ml. The title compounds bis(4-methoxybenzyl) 2,6-dimethyl-4-(4-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate and bis(4-chlorobenzyl) 2,6-dimethyl-4-(4-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate exhibited promising larvicidal activity at 65.6% and 72.2%, respectively, when compared with the standard compound at 98.9%.

Synthesis and characterization of a novel series of 1,4-dihydropyridine analogues for larvicidal activity against Anopheles arabiensis.

Computational prediction of polar and non-polar solvent effect on the electronic property of N-BOC- Piperidine-4-Carboxylic acid

Six novel piperidine derivatives, compounds 5 to 10, have been synthesized and their antimicrobial and anti-oxidant activities evaluated using agar disc diffusion (antimicrobial) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity (antioxidant). Compound 9 revealed the least antibacterial activity. Compound 6 exhibited the strongest inhibitory activity and the best minimum inhibitory concentration (MIC) results against the seven bacteria tested in comparison to the other piperidine derivatives (5, 7, 8, 9, and 10). All six piperidine compounds displayed no activity against fungal species, Fusarium verticilliodes, Candida utilus and Penicillium digitatium. Compounds 7 and 8 revealed no activity against all seven fungi tested.  Compounds 5, 6, 9, and 10 revealed varying degree of inhibition against Aspergillus niger, Aspergillus flavus, Saccharomyces cerevisiae and Candida albicans. Compound 8 demonstrated the highest scavenging capacity of 78% at 1000 µg/ml and compound 6 demonstrated the least percentage of scavenging potential of 49% at 1000 µg/ml. All piperidine derivatives tested, revealed antioxidant potentials greater than 49% at 1 mg/ml as compared to the control Rutin, which displayed 97% scavenging capacity at the same concentration.  All piperidine derivatives revealed varying degree of antimicrobial and antioxidant activities.

	Key words: 1,2,5,6-Tetrahydropyridine (THP), piperidine derivatives, antibacterial, antifungal, antioxidant.

Shode Francis

Papers

Antimicrobial and antioxidant activities of piperidine derivatives