Impact of Altitudes and Habitats on Valerenic Acid,Total Phenolics,Flavonoids, Tannins,and Antioxidant Activity of <Emphasis Type="Italic">Valeriana jatamansi</Emphasis>

The changes in total phenolics, flavonoids, tannins, valerenic acid, and antioxidant activity were assessed in 25 populations of Valeriana jatamansi sampled from 1200 to 2775 m asl and four habitat types of Uttarakhand, West Himalaya. Significant (p?<?0.05) variations in total phenolics, flavonoids, valerenic acid, and antioxidant activity in aerial and root portions and across the populations were observed. Antioxidant activity measured by three in vitro antioxidant assays, i.e., 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic) (ABTS) radical scavenging, 2,2′-diphenyl-1-picryylhydrazyl (DPPH) free radical scavenging, and ferric-reducing antioxidant power (FRAP) assays, showed significant (p?<?0.05) differences across the populations. However, no clear pattern was found in phytochemicals across the altitudinal range. Among habitat types, (pine, oak, mixed forest, and grassy land), variation in phytochemical content and antioxidant activity were observed. Equal class ranking, neighbor-joining cluster analysis, and principal component analysis (PCA) identified Talwari, Jaberkhet, Manjkhali, and Khirshu populations as promising sources with higher phytochemicals and antioxidant activity. The results recommended that the identified populations with higher value of phytochemicals and antioxidants can be utilized for mass multiplication and breeding program to meet the domestic as well as commercial demand.     

Axially chiral biaryl diols catalyze highly enantioselective hetero-Diels-Alder reactions through hydrogen bonding

Axially chiral 1,1'-biaryl-2,2'-dimethanol (3, BAMOL) family of diols are highly effective catalysts for enantioselective hetero-Diels-Alder reactions between aminosiloxydiene 1 and a wide variety of unactivated aldehydes. The reactions proceed in useful yields and excellent enantioselectivities. The diols function in the same capacity as Lewis acids, by activating the aldehyde carbonyl group through hydrogen bonding.     

Multifunctional palladium catalysis. 2. Tandem haloallylation followed by Wacker-Tsuji oxidation or sonogashira cross-coupling

[reaction: see text] Multifunctional palladium catalysis is utilized in the one-pot stereocontrolled synthesis of tetrasubstituted methyl ketones and enynes. The homogeneous palladium dihalide catalyst utilized for the bromo-/chloroallylation of alkynes is reused in situ for subsequent Wacker-Tsuji oxidation or Sonogashira cross-coupling.     

A convenient synthesis of t-butyldimethylsilyl protected cyanohydrins

A simple high yielding procedure is described for the direct conversion of aldehydes to t-butyldimethylsilyl (TBS) protected cyanohydrins using TBSCl, KCN and ZnI₂.     

Hydrogen bond catalyzed enantioselective vinylogous Mukaiyama aldol reaction

[chemical reaction: see text]. The concept of hydrogen bonding catalysis was extended to the vinylogous Mukaiyama aldol reaction, which gives rapid access to polyketide derivatives. The reaction of the silyldienol ether shown and a range of aldehydes catalyzed by TADDOL proceeds regiospecifically to produce the addition products in good yields and enantiomeric excesses.     

Sequential effects of ultraviolet radiation on the histomorphology, cell density and antioxidative status of the lens epithelium--an in vivo study

In vivo progressive effects of UV irradiation on the lens epithelium were studied using various histomorphological and biochemical parameters. Fifteen day old rat pups were exposed to 600 mW/m2 of radiation, including UV-A and UV-B, 12 h daily for 90, 120, 150 and 180 days. Biochemical parameters such as protein-bound and non-protein-bound sulfhydryl groups in both soluble and insoluble fractions and enzymes, which play an important role in combating the oxidative stress, were studied. Decreased cell density of lens epithelial cells (LEC) was observed in all three zones along with the decrease in the levels of soluble sulfhydryls (S-SH), glutathione reductase (GR), superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT). On the other hand, an increase in insoluble sulfhydryls was observed. Because of the decrease in S-SH and GR activities, the LEC became vulnerable to oxidative stress. Decreased activities of SOD, GPx and CAT suggest elevated oxidative stress. This effect of UV radiation may lead to cell death that may be responsible for the observed decrease in the cell density in all three zones of the lens epithelium.     

Racemic and asymmetric Diels-Alder reactions of 1-(2-oxazolidinon-3-yl)-3-siloxy-1,3-butadienes

Achiral and chiral 1-(2-oxazolidinon-3-yl)-3-siloxy-1,3-butadienes were prepared from readily available starting materials. Although more stable than the parent 1-amino-3-siloxy dienes, the 1-(2-oxazolidinon-3-yl)-3-siloxy-1,3-butadienes are still very reactive in Diels-Alder reactions, somewhat more than 1,3-dialkoxy-1, 3-butadienes (e.g., Danishefsky's diene). The cycloadditions of the achiral and chiral dienes with several different dienophiles were examined. The reactions proceeded in good yield, with modest to high endo selectivity. The chiral dienes exhibited excellent facial selectivity in cycloadditions with alpha-substituted acroleins, maleic anhydride and N-phenylmaleimide. Upon reduction and hydrolysis of the cycloadducts, substituted cyclohexenones were obtained with ee's ranging from 22% to >98%.     

Insight into Bioactivity of In-situ Trapped Enzyme-Covalent-Organic Frameworks

Selecting a suitable support material for enzyme immobilization with excellent biocatalytic activity and stability is a critical aspect in the development of functional biosystems. The highly stable and metal-free properties of covalent-organic frameworks (COFs) make them ideal supports for enzyme immobilization. Herein, we constructed three kinds of COFs via a biofriendly and one-pot synthetic strategy at room temperature in aqueous solution. Among the three developed COFs (COF-LZU1, RT-COF-1 and ACOF-1), the horseradish peroxidase (HRP)-incorporated COF-LZU1 is found to retain the highest activity. Structural analysis reveals that a weakest interaction between the hydrated enzyme and COF-LZU1, an easiest accessibility by the COF-LZU1 to the substrate, as well as an optimal conformation of enzyme together promote the bioactivity of HRP-COF-LZU1. Furthermore, the COF-LZU1 is revealed to be a versatile nanoplatform for encapsulating multiple enzymes. The COF-LZU1 also offers superior protection for the immobilized enzymes under harsh conditions and during recycling. The comprehensive understanding of interfacial interactions of COF host and enzyme guest, the substrate diffusion, as well as the enzyme conformation alteration within COF matrices represents an opportunity to design the ideal biocatalysts and opens a broad range of applications of these nanosystems.     

Investigation of amodiaquine bulk drug impurities by liquid chromatography/ion trap mass spectrometry

Three unknown impurities in an amodiaquine bulk drug sample were detected by reversed-phase high-performance liquid chromatography with ultraviolet detection (HPLC/UV). A liquid chromatography/tandem mass spectrometry (LC/MS(n)) method is described for the investigation of these impurities. Mass spectral data were acquired on an LCQ ion trap mass analyzer equipped with an electrospray ionization (ESI) source operated in positive ion mode. The fragmentation behavior of amodiaquine and its impurities has been studied. Based on the mass spectral data and the specifics of the synthetic route, the possible structures of these impurities were elucidated as 4-[(5-chloroquinolin-4-yl)amino]-2-(diethylaminomethyl)phenol (impurity I), 4-[(7-chloroquinolin-4-yl)-amino]phenol (impurity II) and 4-[(7-chloroquinolin-4-yl)amino]-2-(diethylaminomethyl)-N(1)-oxy]phenol (impurity III). The structures were confirmed by their independent synthesis and NMR spectral assignment.