Physicochemical Properties of Starch from Dioscorea pyrifolia tubers.

Starch from Dioscorea pyrifolia tubers was characterized for its proximate composition, physicochemical properties and toxicity. This starch contains 44.47±1.86% amylose, 4.84±0.29% moisture, 0.88±0.21% ash, 1.34±0.11% proteins and 92.73±0.48% carbohydrates. X-ray diffraction (XRD) analysis showed a type-C starch with a relative crystallinity of 23.31±2.41%. The starch granules are polyhedral, with a diameter of 2.8 to 5.6µm and average size of 3.93±1.47µm. Initial, peak and finishing gelatinization temperatures for the starch were 71.51±0.07, 75.05±0.15, and 78.25±0.18°C, respectively; the gelatinization enthalpy was 3.86±0.02J/g, and the peak height index was 1.09±0.05. Thermogravimetric analysis showed a weight loss of 85.81±0.52% and a decomposition temperature of 320.16±0.35°C, which indicated that there was good thermal stability of the starch. Fish embryo toxicity (FET) showed that the starch was not toxic and that it was suitable for food and non-food industries.

Isolation and identification of anti-methicillin resistant Staphylococcus aureus compounds from Phyllanthus columnaris stem bark

Aim: Phyllanthus columnaris Müll.Arg. was found to possess anti-methicillin resistant Staphylococcus aureus (antiMRSA) activities. This study aimed at isolating, identifying and evaluating the active compounds from the stem bark of Phyllanthus columnaris Müll.Arg. against MRSA. Methodology and results: Stem bark extracts (methanol, acetone and aqueous) of Phyllanthus columnaris were subjected to anti-MRSA screening by disc diffusion method. MIC and MBC tests were carried out to compare the lowest concentration to inhibit and kill the sixteen MRSA tested among the three extracts. TLC bioautography were performed to detect the bioactive compounds. Isolation of the two active compounds was performed by means of preparative TLC. Morphological and ultra-structure alterations of the MRSA treated with bioactive compounds after 24 h were revealed by scanning and transmission electron microscopy. Both methanol and acetone extracts exhibited good anti-MRSA activity with the lowest minimum inhibitory concentration (MIC) value for both extracts were 0.78 mg/mL and the lowest minimum bactericidal concentration (MBC) were 1.56 mg/mL. Bioassay-guided chromatography by bioautography revealed two active anti-MRSA compounds from both tannin-free methanol and acetone extracts and characterized as stigmasterol and lupeol by nuclear magnetic resonance (NMR) spectral data. Scanning and transmission electron microscopy of MRSA treated with stigmasterol and lupeol showed cell wall disruption, release of cytoplasmic compounds and decreased in cellular volume. Conclusion, significance and impact of study: Results obtained herein, may suggest that the stem bark of Phyllanthus columnaris possess anti-MRSA and the two of the active compounds isolated were stigmasterol and lupeol. Their anti-MRSA effects up to the morphological and ultra-structure studies were not reported earlier

Synthesis, antibacterial activity and cytotoxicity of new fused pyrazolo[1,5-a]pyrimidine and pyrazolo[5,1-c][1,2,4]triazine derivatives from new 5-aminopyrazoles.

New 5-aminopyrazoles 2a-c were prepared in high yields from the reaction of known α,α-dicyanoketene-N,S-acetals 1a-c with hydrazine hydrate under reflux in ethanol. These compounds were utilized as intermediates to synthesize pyrazolo[1,5-a]-pyrimidines 3a-c, 4a-d, 5a-c, and 6a-c, as well as pyrazolo[5,1-c][1,2,4]triazines 7a-c and 8a-c, by the reaction of 2-[bis(methylthio)methylene]malononitrile, α,α-dicyanoketene-N,S-acetals 1a-b, acetylacetone, acetoacetanilide as well as acetylacetone, and malononitrile, respectively. Furthermore, cyclization of 2a-c with pentan-2,5-dione yielded the corresponding 5-pyrrolylpyrazoles 9a-c. Moreover, fusion of 2a-c with acetic anhydride resulted in the corresponding 1-acetyl-1H-pyrazoles 10a-c. The antibacterial activity and cytotoxicity against Vero cells of several selected compounds are also reported.

3-Amino-5-(piperidin-1-yl)thio-phene-2,4-dicarbonitrile.

In the title compound, C(11)H(12)N(4)S, the thio-phene ring is roughly planar, with a maximum deviation of 0.012 (1) Šfor the S atom, and makes a dihedral angle of 7.89 (8)° with the mean plane of the piperidine ring, which is in a chair conformation. The crystal packing is stabilized by pairs of centrosymmetric inter-molecular N-H⋯N hydrogen bonds, which results in the formation of a step-wise chain parallel to [10[Formula: see text]].

3-Oxo-5-(piperidin-1-yl)-2,3-dihydro-1H-pyrazole-4-carbonitrile.

In the title compound, C(9)H(12)N(4)O, the piperidine ring adopts a chair conformation and makes a dihedral angle of 42.49 (11)° with the approximately planar pyrazole moiety [maximum deviation = 0.038 (2) Å]. In the crystal, N-H⋯O and N-H⋯N hydrogen bonds and a weak C-H⋯O inter-action link the mol-ecules into sheets lying parallel to (110).