Efficacy of silver and gold nanoparticles obtained from vermiwash: In vitro study on antimicrobial and antidiabetic activities

Emerging nanobiotechnology has provided innovative techniques to synthesize nanoparticles through biological methods to explore the potentialities of biological sources like phytoextracts, microbes, animal secretions and excretion. This research studies the potential of vermiwash to synthesize the silver and gold nanoparticles and evaluate its in vitro effect of antimicrobial   and antidiabetic activities. The characterization of the nanoparticles was analyzed through various techniques. Ultraviolet (UV)-Visible spectroscopy showed the maximum absorption spectrum at 413 nm for silver and 541 nm for gold nanoparticles. Fourier transform infrared spectroscopy (FTIR) revealed the reducing agent involved in nanoparticles synthesis. Scanning electron microscope (SEM) images revealed the size of the silver and gold nanoparticles as 24 nm and 50 nm, respectively. Energy dispersive X-ray (EDAX) analysis revealed the elemental composition of the synthesized nanoparticles. X-ray diffraction (XRD) analysis confirmed the crystalline nature of the nanoparticles that displayed the preferential orientation of the crystals toward the (111) plane.  Antimicrobial activity was assessed using the resazurin assay method.  A minimum inhibitory concentration (MIC) of less than 7.8 µg was observed in Staphylococcus aureus and Klebsiella pneumoniae. In the antifungal activity, MIC at 250 µg was noted in Mucor sp. and Candida albicans. Antidiabetic activity was assessed by α-amylase and α-glucosidase inhibitory assay. IC50 of α-amylase and α-glucosidase activity of the silver nanoparticles was noted as 218 and 221 µg/mL, respectively. IC 50 value for the enzymatic assay dose-dependently confirmed the effect. Conclusively biosynthesized nanoparticles from vermiwash showed potential efficiency of antibacterial, antifungal and antidiabetic activities

5-Acetyl-4-(2-chloro­phen­yl)-6-methyl-3,4-dihydro­pyrimidine-2(1H)-thione

In the title mol­ecule, C13H13ClN2OS, the heterocyclic ring adopts a flattened boat conformation with the plane through the four coplanar atoms making a dihedral angle of 85.6 (1)° with the benzene ring, which adopts an axial orientation. The thionyl, acetyl and methyl groups all have equatorial orientations. Inter­molecular N—H⋯O, N—H⋯S and C—H⋯S hydrogen bonds are found in the crystal structure. A weak C—H⋯π inter­action involving the benzene ring also occurs

Two-dimensional NMR spectral studies of some 2,6-diarylpiperidin-4-ones

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2,3,5-Triphenyl­pyrazine

In the title mol­ecule, C22H16N2, the pyrazine ring deviates very slightly from planarity [maximum deviation 0.044 (3) Å], tending towards a twist-boat conformation. The phenyl ring at position 3 makes dihedral angles of 64.0 (2) and 45.8 (2)°, respectively, with the phenyl rings at positions 2 and 5. The dihedral angle between the phenyl rings at positions 2 and 5 is 49.7 (2)°. A C—H⋯π inter­action is found in the crystal structure, but no classical hydrogen bonds form

1-Benzyl-3,5-bis­[(E)-3-thienyl­methyl­idene]piperidin-4-one

In the title mol­ecule, C22H19NOS2, the piperidine ring adopts an envelope conformation with the benzyl substituent in an equatorial position. Each of the olefinic double bonds has an E configuration. The dihedral angle between the two thio­phene rings is 1.55 (18)°. The thio­phene rings form angles of 72.21 (14) and 73.43 (14)° with the phenyl ring. Both thio­phene rings are disordered over two orientations [occupancy ratios of 0.799 (1):0.201 (1)] at 180° from one another. In the crystal, weak inter­molecular C—H⋯O hydrogen bonds and C—H⋯π inter­actions help to stabilize the packing

Ethyl 4-(4-bromo­phen­yl)-6-r-phenyl-2-oxocyclo­hex-3-ene-1-t-carboxyl­ate

In the title compound, C21H19BrO3, the cyclo­hexene ring adopts an envelope conformation, with all substituents equatorial. The plane through its five coplanar atoms makes dihedral angles of 28.88 (10) and 71.94 (10)° with the bromo­benzene and phenyl rings, respectively. The dihedral angle between the latter two rings is 51.49 (15)°. Inter­molecular C—H⋯O hydrogen bonds are found in the crystal structure; a C—H⋯π inter­action is also present

2-Methyl-3,5,6-triphenyl-2,3-dihydro­pyrazine

In the title mol­ecule, C23H20N2, the heterocyclic ring adopts a screw-boat conformation, with all substituents equatorial. The phenyl ring at position 3 makes dihedral angles of 78.12 (15) and 72.67 (15)°, respectively, with the phenyl rings at positions 5 and 6; the dihedral angle between the phenyl rings at positions 5 and 6 is 67.32 (14)°. A C—H⋯π inter­action is present in the crystal structure

2-(2-Chloro­phen­yl)-3-methyl-5,6-diphenyl-2,3-dihydro­pyrazine

In the title mol­ecule, C23H19ClN2, the heterocyclic ring adopts a screw-boat conformation, with all substituents equatorial. The benzene ring at position 2 makes dihedral angles of 77.88 (12) and 76.31 (12)° with the phenyl rings at positions 5 and 6, respectively. The dihedral angle between the phenyl rings at positions 5 and 6 is 70.05 (10)°. The Cl atom is disordered over two positions with occupancy factors of 0.946 (5) and 0.054 (5). In the crystal, C—H⋯π inter­actions are found

5-Acetyl-4-(2-chloro­phen­yl)-6-methyl-3,4-dihydro­pyrimidin-2(1H)-one

In the title mol­ecule, C13H13ClN2O2, the heterocyclic ring adopts a flattened boat conformation with the plane through the four coplanar atoms making a dihedral angle of 89.16 (5)° with the benzene ring, which adopts an axial orientation. The carbonyl, acetyl and methyl groups each have an equatorial orientation. In the crystal structure, inter­molecular N—H⋯O hydrogen bonds lead to a tape motif. The H atoms of the methyl group at position 6 are disordered over two positions of opposite orientation

2-r-(4-Chloro­phen­yl)-6-c-phenyl-3,4,5,6-tetra­hydro-2H-thio­pyran-4-one 1-oxide

The thio­pyran unit of the title mol­ecule, C17H15ClO2S, is in chair form. A crystallographic mirror plane bis­ects the mol­ecule, passing through the O=S and the opposite C=O atoms of the central ring, with statistical disorder of the Cl atom. The geometry around the S atom is tetra­hedral and the carbonyl C is planar. The 4-chloro­phenyl group at the 2 position and the phenyl ring at the 6 position have equatorial orientations. Inter­molecular C—H⋯O and C—H⋯Cl hydrogen bonds are found in the crystal structure. In addition, there is a short O⋯C inter­molecular contact [2.970 (5) Å]