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There has been much consideration over whether exogenous ketone bodies have the capacity to enhance exercise performance through altered substrate metabolism. This systematic review aimed to determine the effects of both ketone precursors and monoesters on endurance exercise performance. A systematic search was conducted in PubMed, SPORTDiscus, and CINAHL for randomized controlled trials investigating endurance performance outcomes in response to ingestion of a ketone supplement compared to a nutritive or non-nutritive control in humans. A meta-analysis was performed to determine the standardized mean difference between interventions using a random-effects model. Hedges’ g and 95% confidence intervals (CI) were reported. The search yielded 569 articles, of which 8 were included in this review (80 participants; 77 men, 3 women). When comparing endurance performance amongst all studies, no significant differences were found between ketone and control trials (Hedges g=0.136; 95% CI, -0.195, 0.467; p=0.419). Sub-analyses based on type of endurance tests showed no significant differences in time to exhaustion (Hedges g=-0.002; 95% CI, -0.312, 0.308; p=0.989) or time trial (Hedges g=0.057; 95% CI, -0.282, 0.395; p=0.744) values. Based on these findings, exogenous ketone precursors and monoesters do not significantly improve endurance exercise performance. While all studies reported an increase in blood ketone concentrations after ingestion, ketone monoesters appear to be more effective at raising concentrations than precursors.

<p> The photo-addition of 2-cyclohexenone to norbornadiene has been investigated. A substantial proportion of the products formed were α, β unsaturated ketones. The structure of these has been assigned and a rationale is presented to explain the formation of these products. </p> / Thesis / Master of Science (MSc)

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Since the ordinary methods for the preparation of a-diketones are rather long and rarely yield a high percentage of product, the attempt was made to perfect some short, simple, direct method whereby the straight and mixed a-diketones could be prepared. / M.S.

Benzophenone (BP) and substituted BPs constitute a major class of aromatic ketones and are of potential interest in various areas of excited state solution phase photochemistry and photobiology. High triplet state energy, faster rate of intersystem crossing (ISC) and higher triplet state quantum yield enables BP systems as potential photosensitizers via triplet energy transfer mechanism. The short lived triplet state of BP systems are highly reactive and acts as potential electron acceptor and interesting photochemical behavior have been observed for photoinduced electron transfer reactions in various solvent media, in particular for donor-bridgeacceptor (D-B-A) family. Though detailed spectroscopic studies of BP and substituted BP are documented, not much attention are given to its heterocyclic analogue. Substitution of aromatic ring carbon with one or more heteroatom (N and S) results in drastical change in photochemical properties and excited state reactivity. In solution phase and in nanosecond time domain heteroaromatic ketones form the triplet excited state that upon subsequent photoreactions, leads to formation of short lived species viz. radicals, ions and radical ions. Therefore exploring the trends in excited state reactivity with the variation with functional group and ring substitution and solvent medium is of considerable interest. The complete reaction mechanism of a photoreaction can be understood by studying reactivity of various short lived intermediates formed. In solution phase, the reactivity of a certain species or rate of a chemical reaction can be well understood by correlating to its structure. This approach requires accurate reproducible techniques for the excited state structural determination. Wide range of time resolved (TR) spectroscopies spanning over whole electromagnetic spectrum have been developed over decades and successfully applied to study excited state phenomena. In a typical two beam experiment, the pump pulse excites the molecular system to higher electronic state and the probe pulse records the spectrum of intermediate species at variable delay time with respect to the pump. The data from different TR techniques used to be complementary in nature and the combination helps in a deeper understanding of excited state reaction mechanism. Though time resolved absorption (TRA) is the most popular and oldest technique to study the excited state photoreactions, no structural information and the poor spectral resolution of the broad and overlapping absorption bands are the limitations towards predicting the reactive intermediates with accuracy. However time resolved resonance Raman (TR3) spectroscopy is a very sensitive technique to obtain vibrational structural information of short lived intermediates. The position and intensity of highly resolved Raman bands provide information about the structural and kinetics parameters respectively. From a set of Raman spectra along various delay time, structure of multiple intermediates evolved for parallel photoreactions can be predicted accurately. We have employed TRA, TR3 and density functional theoretical (DFT) calculation to address few fundamental questions about effect of solvent and ring substitution on the excited state structure and energetics of heterocyclic ketones, hence the reactivity. Comparing the experimental findings with the theoretical output not only makes the data more accurate but also several additional conclusions can be drawn that could not be performed only with the experimental modality. In chapter 1 of the thesis, we have presented a general summary of photophysical phenomena and measured properties and parameters of heterocyclic ketones. Typical photoreactions involving various related aromatic ketones obtained from literature are discussed. This is followed by a brief account of theory of resonance Raman spectroscopy and density functional theoretical calculation. The objectives of the present investigation are highlighted. The detailed assembly of experimental techniques employed for present investigation is discussed in chapter 2. The lasers, spectrometers, collection optics, detection systems and data collection and analysis procedures are briefly illustrated for individual set up. The theory of methods of DFT calculations is also discussed. The effect of substitution of N atom in the aromatic rings on excited state structure and reactivity (hydrogen abstraction reaction) for isomeric (2, 3, 4) benzoylpyridines (BzPy) in various solvents is studied using the above experimental and theoretical methodologies and is presented in Chapter 3. In neutral solvents viz. acetonitrile and carbon tetrachloride the photogenerated lowest triplet state (T1) is observed to be formed that follow monoexponetial decay. In the presence of hydrogen donating solvents like methanol and isopropanol the triplet state is found to undergo hydrogen abstraction reaction to form a ketyl radical and solvent radical. The lifetime and absorption and Raman features of triplet state and ketyl radicals are entirely different from each other and lack any overlapping characteristics. The observed enhanced reactivity of BzPy in comparison to BP is believed to be because of the introduction of the N hetero atom in one of the phenyl ring. From the theoretical data, it was clear that more planarity is attained in case of BzPy as compared to BP and contributes to the enhanced reactivity. The spin density calculation shows that one third of the spin is localized in the phenyl ring in case of BP. The total spin density on Phenyl ring is 0.62 and on carbonyl group is 1.45. In case of BzPy the spin density on phenyl ring is 0.45 and on carbonyl group is 1.59. This indicates that in the excited state the spin is localized more on the carbonyl group. Also from charge density calculation using DFT it is clear that in the triplet state of BzPy the oxygen atom of C=O group is more positive than in case of BP which makes it more electrophilic. Among the three isomeric BzPy the trend in charge density is dependent on the position of nitrogen and found to be in the order of 2-BzPy>3-BzPy>4-BzPy. This can be explained on the basis of -I and –M effect of N atom and the extent depends on its position. So the trend for case of photoreduction follows the order 2-BzPy>3-BzPy>4-BzPy. The hydrogen abstraction reaction used to be considerably fast that produces a substrate ketyl radical and solvent radical (donor radical). These radicals further can dimerise to form various photoproducts viz. Pinacols or can form a stable complex between them. The fate of the radicals formed as a result of hydrogen abstraction of 4-BzPy and the accurate characterization of the adduct is explained in Chapter 4. In the present case the cross coupling reaction of the radicals is observed at longer delay time to form a light absorbing transient (LAT) which is the dominant pathway over other parallel reactions. The exact position of the donor radical in the complex is predicted by correlating the experimental Raman bands and theoretically obtained structural parameters and vibrational frequency. The adduct formed as a result of cross coupling reaction was identified as p-LAT, 2-[4-(hydroxylpyridylmethylene)cyclohexa-2,5dienyl]propan-2-ol. In case of benzoylthiophenes (BzTh), the effect of substitution of S atom on the excited state structure and reactivity towards various hydrogen donors viz. phenol and indole in different solvents are presented in Chapter 5. The difference in rate and mechanism of photoreaction for both the hydrogen donors are compared. For TPK the T1 state is of ππ* character and the T2 state is of nπ* character as is confirmed by flash photolysis and low temperature phosphorescence spectra in EPA matrix. The CO bond length for the triplet state species is more than that of ground state. In case of the ππ* triplet prominent structural changes in thienyl ring are observed and the phenyl ring remains much unaltered. The reaction of the triplet state species with phenol in two different solvents shows a relatively faster rate of reaction. If only ππ* triplet has been taking part in reaction, it might have resulted in slow reaction rate. Because the reaction rate is fairly high, It is concluded that not only ππ* triplet is involved in reaction but there is a contribution from the little higher energy T2 state having nπ* character. The reactivity trends towards hydrogen transfer reaction for three isomeric dithienyl ketones with respect to the position of heteroatoms in the ring are presented in Chapter 6. Energetically close lying (ππ* and nπ*) triplet states are observed to undergo state switching with the change in position of heteroatom in the ring and thus define the characteristics of the triplet state and plays important role in predicting the reactivity trend. Brief summary of the present investigation along with important possible extensions of the present work in described in Chapter 7.

Malaria continues to cause significant mortality in sub-Saharan Africa and elsewhere, and existing vector control measures are being threatened by growing resistance to pyrethroid insecticides. With the goal of developing new human-safe, resistance-breaking insecticides we have explored several classes of acetylcholinesterase inhibitors. In vitro assay studies demonstrate that tri- and difluoromethyl ketones can potentially inhibit An. gambiae AChE (AgAChE). These compounds inhibit the enzyme by making a covalent adduct with the catalytic serine of AChE. Trifluoromethyl ketones however are poor inhibitors of the G119S resistant mutant of AgAChE. However difluoromethyl ketones can inhibit G119S AgAChE and compound 3-10g showed an IC₅₀ value of 25.1 nM after 23h incubation time. Despite this potent inhibition of AgAChE, the tri-, di-, and (mono)fluoroketones showed very low toxicity to An. gambiae, perhaps due to hydration and rapid clearance. In an attempt to improve An. gambiae toxicity, oximes and oxime ethers of these compounds were prepared as potential prodrugs. These structures identified trifluoromethyl ketone oxime 3-2d as a potent toxin against both wild-type (G3-strain) and a multiply resistant (Akron) strain of An. gambiae. This compound is within 3-fold of the toxicity of propoxur to wild type An. gambiae (LC₅₀ values of 106 and 39 µg/mL, respectively). Most significantly, 3-2d was much more toxic than propoxur to multiply-resistant (Akron) strain An. gambiae (LC₅₀ = 112 and >5,000 µg/mL, respectively). However, thus far we have not been able to link the toxicity of these compounds to a cholinergic mechanism. Pre-incubation studies suggest that significant hydrolysis of these compounds to TFKs does not occur over 22 h at pH 7.7 or 5.5. The mechanism of action of 3-2d remains unknown. Our enzyme inhibition studies have demonstrated that 3-2d does not hydrolyze to the trifluoromethyl ketone 2-9d at pH 7.7. The high Akron toxicity of 3-2d and poor inhibition of G119S AgAChE by 2-9d argue against enzyme mediated conversion of 3-2d to 2-9d within the mosquito. Thus, we can rule out an AChE inhibition mechanism for toxicity. Additional experiments by our collaborator (Dr. Jeffrey Bloomquist, University of Florida) also rule out inhibition of mitochondrial respiration or agonism of the muscarinic acetylcholine receptor. Future work will address other potential insecticidal modes of action. / Ph. D.

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