SignificanceMethane from global rice cultivation currently accounts for one-half of all crop-related greenhouse gas emissions. Several international organizations are advocating reductions in methane emissions from rice by promoting intermittent flooding without accounting for the possibility of large emissions of nitrous oxide (N2O), a long-lived greenhouse gas. Our experimental results suggest that the Indian subcontinent’s N2O emissions from intermittently flooded rice fields could be 30–45 times higher than reported under continuous flooding. Net climate impacts of rice cultivation could be reduced by up to 90% through comanagement of water, nitrogen, and carbon. To do this effectively will require a careful ongoing global assessment of N2O emissions from rice, or we will risk ignoring a very large source of climate impact.

INTRODUCTIONCelecoxib, 4-[5-(4-methylphenyl)-3-trifluoromethyl-1H-pyrazol-1yl] benzene sulphonamide, is a 1,5-diarylsubstituted pyrazole with a pK a of 11.1 (Figure 1). Celecoxib was the first specific inhibitor of cycloxygenase-2 (COX-2) to be approved by the United States Food and Drug Administration (FDA), in 1998. This clinical introduction of celecoxib has been the result of the important discovery of the COX isoenzymes and the subsequent search for molecules effective in selectively inhibiting COX-2 with little or no effect on COX-1. The major clinical goal was to produce a nonsteroidal antiinflammatory drug (NSAID) that had little or no effect on the gastrointestinal (GI) tract and kidney. 1 Celecoxib is used in the treatment of rheumatoid arthritis, osteoarthritis, and for the management of the pain of these conditions.2-4 The aqueous solubility of celecoxib is low at 3 to 7 μg/mL when determined in vitro at pH 7 and 40°C. Since the pK a of celecoxib is 11.1 the solubility of the drug is likely to also be low at physiological pH.5 The oral bioavailability of celecoxib is between 22% and 40%.6 Thus, it is important to enhance the solubility and dissolution rate of celecoxib to improve its overall oral bioavailability.Celecoxib, a specific inhibitor of cycloxygenase-2 (COX-2) is a poorly water-soluble nonsteroidal antiinflammatory drug with relatively low bioavailability. The effect of ȕ-cyclodextrin on the aqueous solubility and dissolution rate of celecoxib was investigated. The possibility of molecular arrangement of inclusion complexes of celecoxib and ȕ-cyclodextrin were studied using molecular modeling and structural designing. The results offer a better correlation in terms of orientation of celecoxib inside the cyclodextrin cavity. Phase-solubility profile indicated that the solubility of celecoxib was significantly increased in the presence of ȕ-cyclodextrin and was classified as A L -type, indicating the 1:1 stoichiometric inclusion complexes. Solid complexes prepared by freeze drying, evaporation, and kneading methods were characterized using differential scanning calorimetry, powder x-ray diffractometry, and scanning electron microscopy. In vitro studies showed that the solubility and dissolution rate of celecoxib were significantly improved by complexation with ȕ-cyclodextrin with respect to the drug alone. In contrast, freeze-dried complexes showed higher dissolution rate than the other complexes.

A wide range of benzo[c]cinnolines are prepared through a sequential C-C and C-N bond formation by means of an oxidative C-H functionalization. The reaction proceeds via the C-arylation of 1-arylhydrazine-1,2-dicarboxylate with aryl iodide using Pd(OAc)2/AgOAc followed by an oxidative N-arylation in the presence of PhI/oxone in trifluoroacetic acid. It is entirely a new strategy to generate the benzo[c]cinnoline libraries with a diverse substitution pattern.

The respiratory oxygen uptake by mesophyll protoplasts of pea (Pisum sativum cv Arkel) was stimulated up to threefold after 15 minutes of Illumination at an intensity of 1250 microeinsteins per square meter per second in the presence of 5 millimolar bicarbonate at 300C. The extent of light-enhanced dark respiration (LEDR) increased progressively with duration of preillumination. The LEDR exhibited two phases. The initial high rate of respiration decreased in about 10 minutes to a lower steady value similar to that before Illumination. The promotion of LEDR by the presence of bicarbonate and inhibition by glyceraldehyde or 3-(3,4-dichlorophenyl)-1,1-dimethylurea suggested that LEDR was dependent on products of photosynthetic carbon assimilation/electron transport. Thus, the photosynthetic products exert a markedly quick influence on dark respiration in mesophyll protoplasts.The carbon and energy economy of a plant depend not only on photosynthesis but also on respiration. The interaction between photosynthesis and respiration, therefore, is very important. Photosynthesis over long periods of illumination leads to an accumulation of carbohydrates, which can stimulate dark respiration (3). The lowering of photosynthetic efficiency at lower light intensities, a phenomenon called the Kok effect (12), is believed to be primarily due to dark respiration (1 1, 16, 17).The magnitude ofmitochondrial (dark) respiration in leaves of higher plants during photosynthesis is not yet clearly established (7, 8). There is a large variation in the reported reduction in dark respiration on illumination, ranging from 0 to 100% (2, 4, 13). Most of the studies to date have been made with intact leaves or leaf discs, which have certain inherent problems, such as recycling of assimilated/released CO2 within the leaf (5), making it difficult to establish the interaction between photosynthesis and respiration (14).We have used isolated mesophyll protoplasts from pea (Pisum sativum cv Arkel) leaves to reevaluate the effect of light on dark respiration. Protoplasts are useful tools for studying plant metabolism because they form homogeneous suspensions; pose no problem of recycling of gas, as within ' (20) have demonstrated a strong interaction between photosynthesis and respiration in mesophyll protoplasts of pea.Our results indicate that there is a marked upsurge in respiratory 02 uptake after even short periods ofillumination. This phenomenon, termed LEDR,2 appears to be related to photosynthetic carbon metabolism/electron transport. As this article was under preparation, LEDR was described in leaves (19). This article is the first report of LEDR in protoplasts. MATERIALS AND METHODSThe first and second fully expanded leaves from 8-to 10-d-old plants of pea (Pisum sativum L. cv Arkel) grown outdoors (natural photoperiod of approximately 12 h; average daily temperatures of 30C day/20C night) were used. The leaves were picked from the plants between 9:00 and 10:00 AM, by which time the plants were exposed to sunlight for about 3 or...

The novel strategy is based on an oxidative two‐step transformation of hydrazine dicarboxylates with aryl iodides.

The respiratory uptake or photosynthetic evolution of oxygen by mesophyll protoplasts of pea (Pisum sativum L. cv. Arkel) were monitored during successive short. (3–5 min) cycles of darkness and illumination. The rate of respiration was nearly doubled after 3–4 short periods of illumination while there was a 15–20% enhancement in photosynthesis with cycles of illumination and darkness preceding illumination. Such interaction between photosynthesis and respiration was statistically significant when bicarbonate was present in the reaction medium. The inhibitors of photosynthesis [3(3,4–dichlorophenyl)‐l,l‐dimethylurea (DCMU), glyceraldehyde] decreased respiration after periods of illumination, whereas inhibitors of respiratory electron transport (Rotenone, antimycin A, NaN3) suppressed photosynthesis, as well. We suggest that a rapid beneficial interaction exists between photosynthesis and respiration in protoplasts, even during short cycles of light and darkness.

Cascade cyclization of a 3‐[(3‐methylbut‐2‐enylamino)methyl]but‐3‐en‐1‐ol derivative with aldehydes in the presence of TMSOTf at 0 °C under mild conditions provides the corresponding spiropyrrolidine scaffolds in good yields. Similar cyclization of a 3‐[(4‐methylpent‐3‐enylamino)methyl]but‐3‐en‐1‐ol derivative with aldehydes affords the correponding spiropiperidine compounds. This is a new approach for the construction of biologically relevant spirocycles in a single‐step process.

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