Total synthesis of (+)-lentiginosine from d-glucose

A total synthesis of (+)-lentiginosine, a potent and selective amyloglucosidase inhibitor, is reported from a d-glucose-derived epoxide in 38% overall yield. In this synthesis, ambient conditions and readily available starting materials and reagents are used.     

Investigation of 500 keV Si ion induced surface structuring of Ni and Ti for enhancement of field emission properties

The present paper reports the investigation of surface morphology, elemental composition, phase changes and field emission properties of Si ion irradiated nickel (Ni) and titanium (Ti). The Ni and Ti targets have been irradiated with 500 keV Si ions generated by Pelletron accelerator at various fluences ranging from 6.9 × 10¹³ to 77.1 × 10¹³ ions/cm². Stopping range of ions in matter analysis revealed higher values of electronic stopping and sputtering yield for Ni as compared with Ti. For both irradiated metals, electronic energy loss dominant over the nuclear stopping. The growth of induced surface structures have been analysed by using field emission scanning electron microscopy (FESEM) analysis. In case of Ni, as the ion fluence increases from 6.9 × 10¹³ to 65.8 × 10¹³ ions/cm², the formation of spherical particulates, agglomers and sputtering is observed. Although in the case of Ti, with the increase of Si ion fluence from 11.6 × 10¹³ to 77.1 × 10¹³ ions/cm², the formation of irregular-shaped particulates along with crater and sputtered channels is observed. X-ray diffraction (XRD) analysis shows that no new phase is identified. However, a significant increase in peak intensity is observed with increasing ion fluence. The variation in crystallite size and dislocation line density is also observed as a function of Si ion fluence. Fourier transform infrared spectroscopy analysis shows that no bands are formed after the Si ion irradiation. Field emission properties of ion-structured Ni and Ti are well correlated with the growth of surface structures observed by SEM and dislocation line density evaluated by XRD analysis.     

New terpenoids from Stachys parviflora Benth

Two new triterpenoidal saponins were isolated from the n-butanolic extract of Stachys parviflora (Lamiaceae). Their structures were elucidated on the basis of spectral data as stachyssaponin A; 3beta, 15alpha, 19alpha, 21beta, 22alpha-pentahydroxyolean-12-ene-28-oic acid 3-O-{alpha-L-rhamnopyranosyl-(1 --> 3)-beta-D-glucopyranoside}-22-O-{alpha-L-arabinofuranosyl-(1 --> 3)-beta-D-glucopyranoside} (1) and stachyssaponin B; 2beta, 3beta, 15alpha, 21beta-tetrahydroxyolean-12-ene-28-oic acid 2-O-[alpha-L-arabinofuranoside]-3, 21-bis-O-[beta-D-glucopyranoside] (2).     

Recovery of butanol from model ABE fermentation broths using MFI adsorbent: a comparison between traditional beads and a structured adsorbent in the form of a film

Butanol, a promising biofuel, can be produced by ABE (acetone, butanol and ethanol) fermentation using e.g. Clostridium acetobutylicum. However, the butanol concentration in the resulting broth is limited to only ca. 20 g/L due to the toxicity for the microorganisms. This low product concentration demands an efficient recovery process for successful commercialization of this process. In this study, a structured adsorbent in the form of steel monolith coated with a silicalite-1 film was prepared using the in situ growth method. The adsorbent was carefully characterized by SEM and XRD. The performance of the adsorbent was evaluated by performing breakthrough experiments at room temperature using model ABE fermentation broths and the performance was compared with that of traditional adsorbents in the form of beads. The structured silicalite-1 adsorbent showed less saturation loading time as compared to commercial binder free silicalite-1 beads, reflecting the different dimensions of the columns used, set by experimental constraints. Studies of the desorption process showed that by operating at appropriate conditions, butanol with high concentration i.e. up to 95.2 wt% for butanol–water model system and 88.5 wt% for ABE fermentation broth can be obtained using the structured silicalite-1 adsorbent. Commercial silicalite-1 beads also showed good selectivity but the concentration of butanol in the desorbed product was limited to 70 % for the butanol–water model system and 69 % for ABE fermentation broth, probably as a result of entrained liquid between the beads.     

Pregnane‐Type Steroidal Alkaloids of Sarcococca saligna: a New Class of Cholinesterase Inhibitors

Phytochemical investigation of Sarcococca saligna by extensive bioassay‐guided fractionation resulted in the isolation of the pregnane‐type steroidal alkaloids 1 – 15 , i.e. of the five new compounds 1 – 5 and the ten known alkaloids 6 – 15 . The structures of the new alkaloids salignenamide C ( 1 ), salignenamide D ( 2 ), 2β‐hydroxyepipachysamine D ( 3 ), salignenamide E ( 4 ), and salignenamide F ( 5 ) were elucidated with the help of modern spectroscopic techniques, while the known alkaloids axillarine C ( 6 ), axillarine F ( 7 ), sarcorine ( 8 ), N³‐demethylsaracodine ( 9 ), saligcinnamide ( 10 ), salignenamide A ( 11 ), vaganine A ( 12 ), axillaridine A ( 13 ), sarsalignone ( 14 ), and sarsalignenone ( 15 ) were identified by comparing their spectral data with those reported earlier. Inhibition of electric‐eel acetylcholinesterase (EC 3.1.1.7) and horse‐serum butyrylcholinesterase (EC 3.1.1.8) by alkaloids 1 – 15 were investigated. These new cholinesterase inhibitors may act as potential leads in the discovery of clinically useful inhibitors for nervous‐system disorders, particularly by reducing memory deficiency in Alzheimer's disease patients by potentiating and effecting the cholinergic transmission process. These compounds were found to inhibit both enzymes in a concentration‐dependent fashion with the IC₅₀ values ranging from 5.21–227.92 μM against acetylcholinesterase and 2.18–38.36 μM against butyrylcholinesterase.     

De novo design, synthesis and spectroscopic characterization of chiral benzimidazole-derived amino acid Zn(II) complexes: Development of tryptophan-derived specific hydrolytic DNA artificial nuclease agent

Novel ternary dizinc(II) complexes 1-3, derived from 1,2-bis(1H-benzimidazol-2-yl)ethane-1,2-diol and l-form of amino acids (viz., tryptophan, leucine and valine) were synthesized and characterized by spectroscopic (IR, (1)H NMR, UV-vis, ESI-MS) and other analytical methods. To evaluate the biological preference of chiral drugs for inherently chiral target DNA, interaction of 1-3 with calf thymus DNA in Tris-HCl buffer was studied by various biophysical techniques which reveal that all these complexes bind to CT DNA non-covalently via electrostatic interaction. The higher K(b) value of L-tryptophan complex 1 suggested greater DNA binding propensity. Further, to evaluate the mode of action at the molecular level, interaction studies of complexes 1 and 2 with nucleotides (5'-GMP and 5'-TMP) were carried out by UV-vis titrations, (1)H and (31)P NMR which implicates the preferential selectivity of these complexes to N3 of thymine rather than N7 of guanine. Furthermore, complex 1 exhibits efficient DNA cleavage with supercoiled pBR322. The complex 1 cleaves DNA efficiently involving hydrolytic cleavage pathway. Such chiral synthetic hydrolytic nucleases with asymmetric centers are gaining considerable attention owing to their importance in biotechnology and drug design, in particular to cleave DNA with sequence selectivity different from that of the natural enzymes.     

A new bisabolane sesquiterpenoid and a new abietane diterpenoid from Cephalotaxus sinensis

Phytochemical investigation of Cephalotaxus sinensis has led to the isolation of a new bisabolane sesquiterpenoid (1), a new abietane diterpenoid (2), and 13 known compounds (3–15). Their structures were elucidated by extensive spectroscopic analysis (MS, UV, IR, and NMR).     

Absolute configuration of 1β,10β-epoxydesacetoxymatricarin isolated from Carthamus oxycantha by means of TDDFT CD calculations

The absolute configuration of 1β,10β-epoxydesacetoxymatricarin 1, a sesquiterpenoid isolated from Carthamus oxycantha, was established by TDDFT CD calculations in combination with single crystal X-ray analysis. Since the solid-state CD spectrum shows contributions from intermolecular interactions in the crystal, 1 represents a test case for our solid-state CD/TDDFT approach.     

A study of redox properties of hydralazine hydrochloride,an antihypertensive drug

Hydralazine hydrochloride itself is a reducing agent and its redox properties like other reducing agents vary as the oxidizing agent and applied conditions vary. The redox properties of hydralazine were studied by spectrophotometric method. Formal redox potential of hydralazine was calculated and effect of pH was observed on redox properties of hydralazine.     

Nonlinear absorption properties correlated with the surface and structural changes of ultra short pulse laser irradiated CR-39

We have investigated femtosecond laser irradiation effects on the surface topography, structural changes and nonlinear absorption properties of CR-39. For this purpose, a CR-39 target was exposed in air to 25 fs, 800 nm Ti: sapphire laser radiation at fluences ranging from 0.25 J cm⁻² to 3.6 J cm⁻². The surface of irradiated CR-39 probed by an Atomic Force Microscope (AFM) exhibits the formation of several topographical structures, like bumps, explosions and nano cavities. Raman spectroscopy is performed to explore chemical and structural modification of the irradiated target. The spectroscopy reveals changes such as cross linking, bond breaking, formation of new bonds etc. in the fundamental structure of the polymer after irradiation. In order to establish a correlation between morphological and structural changes with the changes in the nonlinear absorption of the irradiated CR-39, a Z-scan technique was employed. A comparison of experimentally obtained data from Z-scan measurements with our calculations predicts the dominance of three-photon absorption in the case of pristine CR-39, whereas for irradiated targets concurrence of three- and two-photon absorption is probable. Nonlinear absorption increases with increasing laser fluences and is well correlated by surface and structural changes revealed by AFM and Raman spectroscopy.