New Pyrimidine‐2‐thiones from Reactions of Amidrazonethiols with 2‐Amino‐1,1,2‐ethenetricarbonitrile and Investigation of Their Antitumor Activity

Reactions of thiosemicarbazones with 2‐amino‐1,1,2‐ethenetricarbonitrile were reported. The reaction occurred in the amidrazonyl site, and new pyrimidine‐2‐thiones were obtained. The reaction mechanism was discussed. The structure of products was elucidated by MS, IR, and NMR spectra together with elemental analyses. The antitumor activity was evaluated against one tumor cell line. Using a standard MTT assay, the effect of the samples on the growth of HepG2 cells was investigated. Half of these compounds showed no cytotoxic effect on HepG2 cells, while the others result in decreasing in the HepG2 cell viability.     

Amination of Malononitrile Dimer to Amidines: Synthesis of 6‐aminopyrimidines

Reactions of amidines with malononitrile dimer in DMF and catalyzed with piperidine are reported. The reaction occurred via amination process followed by cyclization to give racemic 6‐aminopyrimidine compounds. The reaction mechanism was discussed. The structure of products was elucidated by mass spectrometry, IR and NMR spectra together with elemental analyses.     

Efficient Palladium‐Assisted One‐Pot Deprotection of (Acetamidomethyl)Cysteine Following Native Chemical Ligation and/or Desulfurization To Expedite Chemical Protein Synthesis

The acetamidomethyl (Acm) moiety is a widely used cysteine protecting group for the chemical synthesis and semisynthesis of peptide and proteins. However, its removal is not straightforward and requires harsh reaction conditions and additional purification steps before and after the removal step, which extends the synthetic process and reduces the overall yield. To overcome these shortcomings, a method for rapid and efficient Acm removal using Pd^II complexes in aqueous medium is reported. We show, for the first time, the assembly of three peptide fragments in a one‐pot fashion by native chemical ligation where the Acm moiety was used to protect the N‐terminal Cys of the middle fragment. Importantly, an efficient synthesis of the ubiquitin‐like protein UBL‐5, which contains two native Cys residues, was accomplished through the one‐pot operation of three key steps, namely ligation, desulfurization, and Acm deprotection, highlighting the great utility of the new approach in protein synthesis.     

Trends in lipase-catalyzed asymmetric access to enantiomerically pure/enriched compounds

Over the last few years, there has been a dramatic increase in the number of publications in the field of lipase-catalyzed reactions performed in common organic solvents, ionic liquids or even non-conventional solvents. A fairly large percentage of these publications have emerged from organic chemists who have recognized the potential of biocatalysis as a viable and popular technique in organic synthesis. Considerable research has shown that reactions catalyzed by enzymes are more selective and efficiently performed than many of their analogues in the organic chemistry laboratory. This review article focuses on some of the recent developments in the rapidly growing field of lipase-catalyzed asymmetric access to enantiomerically pure/enriched compounds. The literature search is dated back to the last five years and covers some comprehensive examples.     

Officinalioside,a new lignan glucoside from Borago officinalis L.

A new lignan glucoside, officinalioside (1), was isolated from n-BuOH fraction of the aerial parts of Borago officinalis L., together with four known compounds: actinidioionoside (2), roseoside (3), crotalionoside C (4) and kaempferol 3-O-β-D-galactopyranoside (5). The structure of the new compound was established by means of spectroscopic and chemical analyses. Compounds 1 and 2 showed a moderate DPPH radical scavenging activity (IC₅₀: 52.6 ± 1.70 and 41.3 ± 0.25 μM, respectively) comparable with that of the standard trolox (16.6 ± 2.2 μM) without any significant cytotoxicity towards human cell line A549 (IC₅₀ > 100 μM).     

Synthesis, spectroscopic and cytotoxic studies of biologically active new schiff bases derived from p-nitrobenzaldehyde

Thirteen new Schiff bases derived from p-nitrobenzaldehyde were synthesized by condensation with the appropriate amines. An unusual reduction of the p-nitrobenzaldehyde to the corresponding alcohol was also observed in one of the reactions. The structures of the compounds were identified using spectroscopic techniques. Cytotoxicity for the titled compounds was studied against Brine Shrimp, used as the test animal.     

Three New Clerodane Diterpene Derivatives from Casearia Membranacea

Three new clerodane diterpene derivatives were isolated from the leaves of Casearia membranacea Hance collected in Taiwan. The isolated metabolites were identified as caseamembrins P (1), Q (2), and R (3). Identification of the structures was based on detailed analysis of the spectral data, especially 2D NMR.     

Sensory, physicochemical and microbiological quality of irradiated minimally processed cauliflower

Minimally processed cauliflower samples were irradiated, stored at 5 °C for 2 weeks and analyzed for sensory, physicochemical and microbiological qualities at 0th, 7th and 14th days. The data showed highest mean values of 7.93 and 7.57 for appearance and flavor, respectively, for 1.0 kGy treated samples. The D₁₀ values of contaminating microorganisms on cauliflower were 0.20 (Escherischia coli) and 0.24 kGy (Salmonella paratyphae A.) and the resulting 5D₁₀ value was 1.2 kGy. The study revealed that a dose of 1.5 kGy is enough for retention of quality and reduction of microbial load to 5D₁₀ values in cauliflower during 2 weeks storage at refrigerated temperature.