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This thesis describes the development of a novel method for the rapid identification of complex organic materials, including macromolecules, that involves a high temperature simultaneous hydrolysis and derivatisation reaction. In this procedure, aqueous quaternary alkylammonium hydroxides are made to react with a wide range of complex molecular species, including synthetic and natural polymers, under high temperature flash heating conditions. The hydrolysis products are converted to derivatives, such as alkyl esters or alkyl ethers. The reaction forms the basis for a modified pyrolysis gas chromatography (Py-GC) identification technique. Although the process is primarily intended for the rapid identification of polymers which are susceptible to hydrolysis, it is also valuable for characterisation of a variety of hydrolysable lower molecular weight species, such as polymer additives, triglycerides and natural waxes.The reaction takes place when an intimate mixture of an aqueous quaternary alkylammonium hydroxide solution is flash heated with the analyte in a conventional pyrolysis unit, and "on-line" GC-MS is used to separate and identify the reaction products. Analytes included synthetic polyester resins and phenolic polymers, natural products such as lipids and wood extractives, and natural polymers including lignocellulose, proteins and kerogen.Reaction variables, such as temperature, pH analyte particle size, substrate, and the derivatising reagent were studied, in order to find the optimum conditions for the reaction. While the reaction occurs at temperatures as low as 358 degrees celsius, a 770 degrees celsius reaction temperature was adopted to allow direct comparison with Py-GC data. A high pH of the derivatising reagent was found to be necessary to achieve an efficient hydrolysis of the macromolecule. Small particle size gives better conversion to derivatised ++ / products. The nature of the heating substrate did not appear to influence the reaction. Tetraalkylammonium hydroxides (TAAH) were found to be the most effective derivatising reagents for the reaction. Tetramethylammonium hydroxide (TMAH) was the most useful derivatising reagent, since the methyl derivatives of the hydrolysed products were conveniently chromatographed and usually had well known mass spectra. Other TA-AHs were useful for (i) producing higher molecular weight alkyl derivatives of low molecular weight side chains in some polymers, e.g., acetate groups in polyvinyl acetate, (ii) the purpose of determining sites of pre-existing methylation in natural products such as lignocellulose, or (iii) cases where methylation products could be confused with existing pyrolysis products.The reaction mechanism is believed to involve hydrolysis of the organic material, formation of the tetra-alkylammonium salt, and thermal degradation of the quaternary ammonium salt to alkylated derivatives. Some evidence is presented to support this mechanism, which is considered to be ionic in character, rather than a free radical reaction.A detailed study of the reaction of alkyd resins indicated that polyhydric alcohols, polybasic acids, degree of cure, oil length, and rosin acid and epoxy modification could be determined. The reaction of rosin modified phenolic resins (tert-butyl phenol formaldehyde and para-nonyl phenol formaldehyde), gave rosin acid methyl esters and easily identifiable products from the synthetic components.Fatty acid methyl esters could be obtained directly from lipids, such as vegetable oils, without time consuming preparative steps. The problems of base catalysed isomerisation of the double bonds in polyunsaturated fatty acids were overcome by reducing the amount of base used for the reaction. The reaction facilitated the identification of fatty acids in ++ / woolwax, the triglycerides in cosmetic products, and lipids in trace quantities of human fingerprint deposits.A more reliable representation of the chemical structure of lignocellulose in softwood and hardwood species was obtained by the reaction, as compared to conventional PyGC which underestimates the aromatic carboxylic acid moieties. Gymnosperm or angiosperm origin was indicated by the presence of solely guaiacyl, or both guaiacyl and syringyl derived groups, respectively. Other extraneous extractable material was identified simultaneously, including aliphatic and aromatic acids, which would not normally be detected by conventional Py-GC.An alternative method involved extracting the wood with TMAH, followed by pyrolysis of the extract, to give less complex but more specific GC profiles. The TMAH extraction procedure also indicated some characteristic biomarker species as well as guaiacyl and syringyl derived compounds. The pyrolysis of tetraethylammonium hydroxide (TEAH) extracts revealed the sites of pre-existing methylation in the Eucalyptus marginata species.The thermally assisted hydrolysis and alkylation method which has been developed is usually superior to the conventional Py-GC procedure for those polymers which are prone to hydrolysis, since it results in products which are more readily related to the polymer structure. For example, concerted hydrolysis and alkylation of polyester resins results in alkyl carboxylate esters and the alkyl ethers, whereas in conventional Py-GC the products are alkenes and carboxylic acids. Carboxylic acids are more difficult to chromatograph by GC, and aromatic carboxylic acids in particular are susceptible to decarboxylation under the pyrolysis conditions.The reaction procedure has provided an alternative approach to the characterisation of submicrogram quantities of a range of synthetic polymers, natural products and ++ / natural polymers, which has not previously been possible without lengthy chemical degradation procedures. Although it has not displaced the conventional Py-GC technique, it has given a new dimension to the characterisation of organic materials, providing a powerful tool for forensic science investigations and the analysis of complex materials.

The surface functionalisation of polyethylene and polypropylene by industrial and laboratory scale corona treatments and by laboratory flame treatment was studied. The surface sensitive techniques of X-ray photoelectron spectroscopy (XPS), attenuated total reflection infra-red spectroscopy (FTIR-ATR), contact angle measurement and electron microscopy (SEM and TEM) were employed. Corona and flame treatments resulted in incorporation of oxygen only into the surfaces of both polyethylene and polypropylene, resulting in improved surface wettabilities. A variety of oxygen functional groups were introduced by the two treatments. The industrial and laboratory scale treatments of both polymers were found to be similar in terms of the oxygen concentrations incorporated and surface wettabilities achieved. The presence of significant amounts of chain scission products were indicated on corona treated surfaces, while only minimal quantities were indicted on flame treated surfaces. This was attributed to their volatilisation during flame treatment. Introduction of sulfur dioxide into the flame and corona regions during treatment resulted in significant improvements in surface wettability. Incorporation of sulfur and nitrogen resulted from the presence of sulfur dioxide. A possible mechanism involving the formation of sulfonic acid groups and ammonium sulfonate groups was suggested. An oxidation depth model developed for use with variable take-off angle XPS showed that significantly deeper oxidation occurred in the presence of sulfur dioxide. Corona treatment was more effective in improving surface wettabilities than flame treatment, this being attributed to heat induced functional group reorientation during flame . treatment for polyethylene and to differences in surface chemistry resulting from the two treatments in the case of polypropylene. The surface wettability of poly ethylene was more readily improved than the surface wettability of polypropylene after all the treatments investigated. A method for estimating functional group concentrations using chemical derivatisation and contact angle measurement was developed. Functional group estimates for flame treated polyethylene were found to be in good agreement with chemical derivatisation used in conjunction with XPS measurements.

La Directive Cadre sur l'Eau (DCE) (2000/60) a mis en place une liste de 33 substances prioritaires, avec des normes qualité de l'environnement (NQE) pour chaque substance, et leur concentration dans les milieux aquatiques qui ne doivent pas dépasser c es NQE. De plus, elle exige des performances analytiques spécifiques pour ces méthodes: la limite de quantification doit être au moins aussi basse que 30% des NQE et l'incertitude de la méthode au niveau de la NQE doit être inférieure à 50%, pour k = 2. Par conséquent, le défi analytique actuel est de mesurer de faibles concentrations de ces polluants dans les matrices parfois difficiles. Ceci peut être réalisé en améliorant la technique d'extraction utilisée pour obtenir un extrait de l'échantillon plus concentré et plus propre. Dans ce contexte, les trois méthodes d'analyse ont été mises au point pour déterminer les composés musqués, alkylphénoliques et organométalliques dans les matrices environnementales. Ces techniques d'extraction et de pré-concentration innovantes ont ensuite été appliquées pour l’évaluation de la présence de ces composés dans les stations d'épuration locales et dans les cours d'eau récepteurs. Enfin, les niveaux de concentrations de fond au niveau national ont été mises à jour pour les composés organométalliques. / The ambitious Water Framework Directive (WFD) (2000/60) set up a list of 33 priority substances, with Environmental Quality Standards (EQS) for each substance, and their concentration in aquatic environments should not go beyond the EQS. Additionally, it requires specific analytical method performances: the limit of quantification must be at least as low as 30 % of the EQS and the uncertainty of the method at the EQS level must be inferior to 50 %, for k=2. Therefore, the current analytical challenge is to measure low concentrations of these pollutants in sometimes difficult matrices. This can be achieved by improving the extraction technique used to obtain a more concentrated and cleaner sample extract. In this context, 3 analytical methods were developed to determine musk, alkylphenols and organometallic compounds in environmental matrices. Recent extraction and pre-concentration techniques were applied and later the occurrence of these compounds in the local WWTPs and in the receiving water bodies where they are discharged was evaluated. Additionally, updated French background concentrations were established for organometallic compounds.

Stereochemistry plays an important role in nature because biologically important molecules such as amino acids, nucleotides and sugars, only exist in enantiomerically pure forms. Semiochemicals carry messages, between the same species (pheromones) and between different species (allelochemicals). Both pheromones and allelochemicals can be used as environmentally friendly pest management. Many semiochemicals, i.e. behaviour modifying chemicals, consist of pure or well-defined mixtures of stereoisomers, where some of the other stereoisomers can be repellent. It is therefore important to be able to separate them to produce a synthetic pheromone in a mixture that is attractive. Pine sawflies are a family of insects that in some cases can be severe defoliators of conifer trees. Diprion pini, Diprion similis and Neodiprion sertifer are severe pests for these trees and have got the most attention in pine sawfly pheromone studies. The pheromone precursors are stored in the female body as long-chain secondary alcohols, which, when released, are esterified to acetates or propionates. The alcohols are chiral, and normally one of the stereoisomer is the main pheromone component, sometimes possible together with other stereoisomers as essential minor components. Bicyclus is a genus of African butterflies, and especially Bicyclus anynana has become a popular model for the study of life history evolution, morphology, mating choice and genetics. The wing pattern of Bicyclus differs depending on the season, with large eyespots during the rain-season and small or absent spots during the dry season.  Euglossa is one of the genera among the orchid bees in the Neotropics that does not produce its own pheromone. Instead, the males collect fragrances from orchids and other sources and store them in a pocket in their hind legs. Both Bicyclus and Euglossa use semiochemicals similar to pine sawflies, and thus can be analysed by the same methods. Pheromones and other semiochemicals in insects are often present in low amounts in a complex matrix, and purification of the sample before chemical analysis is often required. A common method is gradient elution on a solid phase silica column. Separation of stereoisomers can be achieved either by using a column with a chiral stationary phase (CSP) or with pre-column derivatisation using a column with an achiral stationary phase (ASP) or a combination of both, with mass detection as the dominant detection method. The purpose of this work has been to improve the purification method, find suitable methods to separate the stereoisomers of secondary alcohols, and to apply this on extracts of insects. By selecting the right fractions to collect during gradient elution the purification method was optimised. To reduce plasticizer contamination from ordinary columns, solid phase columns of Teflon or glass were used. For pre-column derivatisation of different chiral alcohols various acid chlorides were tested. For the pine sawfly pheromone precursors enantiopure (2S)-2-acetoxypropionyl chloride was the best choice. To separate some of the stereoisomers achiral 2-naphthoyl chloride was used. For derivatisation of 6,10,14-trimethylpentadecan-2-ol (R)-trans-chrysanthemoyl chloride was the best choice. The derivatised alcohols were separated on different columns, both chiral and non-chiral. Varian FactorFour VF-23ms was chosen as a general-purpose column, the Agilent HP-88 column was the best column with an ASP of those tested, and the Chiraldex B-PA column (CSP) was the only one that could separate all eight stereoisomers of derivatised 3,7-dimethylundecan-2-ol, 3,7-dimethyldodecan-2-ol, and 3,7-dimethyltridecan-2-ol. To determine the stereoisomeric purity of standard solutions used in field experiments and extracts of different species of insects the optimised methods were applied. For extracts from B. anynana, Euglossa and Neodiprion lecontei this work describe the first determination of the stereochemistry of some of their semiochemicals. For the determination of the stereochemistry of chiral semiochemicals the methods for purification and separation presented herein have shown to be of great value. The results will hopefully contribute to a better understanding of the communication among insects, and ultimately to a more environmentally friendly pest control. / Många naturligt förekommande kemiska ämnen finns som två spegelbilder av varandra, ungefär som höger och vänster hand. Dessa kan ha helt olika egenskaper och det är därför viktigt att kunna separera dem. Insekter och andra djur använder olika doftämnen för att kommunicera med varandra, om det är inom samma art kallas de för feromoner. De kan bestå av ett ämne eller en blandning av flera. Dessa doftämnen kan man även använda för att på ett miljövänligt sätt bekämpa skadeinsekter. En fälla med syntetiskt feromon för en viss insekt lockar endast till sig den arten, medan alla andra är opåverkade. Eftersom dessa ämnen ofta finns som spegelbilder där kanske bara den ena är aktiv och den andra rent av frånstötande, måste man kunna separera dem för att framställa ett syntetiskt feromon som är attraktivt. Målet med detta arbete har varit att bestämma feromonet hos olika arter av tallsteklar som kan vara svåra skadedjur på tallskog. De metoder som tagits fram har även tillämpats på några arter av afrikanska fjärilar samt orkidébin från Centralamerika eftersom de använder snarlika doftämnen. Att få fram feromonet från en insekt är lite som att leta efter in nål i en höstack eftersom de ofta bara innehåller några miljarddels gram per individ. Provet behöver först renas, och en del av arbetet i det här projektet har gått ut på att ta fram en lämplig reningsmetod. Huvudfokus har dock varit på att ta fram metoder som kan separera och identifiera det eller de ämnen, och spegelbilder av dessa, som doftämnena består av. När lämpliga metoder tagits fram har extrakt av olika insektsarter analyserats. I några fall är det första gången som deras feromon bestämts i detalj. Resultaten kan förhoppningsvis bidra till en ökad kunskap om insekters sätt att kommunicera, och i slutändan till miljövänligare bekämpning av skadeinsekter.

Introduction: Hypertension is an important public health challenge worldwide, being the leading cause of cardiovascular disease, morbidity and mortality. It is particularly prevalent in people in sub-Saharan Africa, especially in urban areas. There is an urgent need to develop strategies to prevent, detect, treat, and control hypertension effectively in the African region. Helicobacter pylori, a gram-negative bacterium responsible for many gastric disorders worldwide, has been associated with hypertension in some previous studies; where blood pressure of patients with Helicobacter pylori infection did not subside after hypertensive treatment, when compared to patients without Helicobacter pylori infections. This effect was suggested to be due to Helicobacter pylori produced and modified cardiotonic steroids that are found in elevated concentrations in hypertensive patients. Cardiotonic steroids are positive inotropic agents which are known to increase blood pressure. A sensitive analytical method is needed to detect and quantify the low concentrations of cardiotonic steroids in biological samples. Materials and Methods: An extraction method was optimised using reversed phase Solid Phase Extraction. A targeted liquid chromatography tandem mass spectrometry method using an Agilent binary series 1100/1200 LC system with a Kinetex C18 RP column (100 x 2.1 mm, 2.6 µm) coupled to a Sciex 4000QTRAP tandem mass spectrometer was developed and validated for the detection and quantitation of 9 different cardiotonic steroids in both solvent and whole blood. The method was validated according to the International Conference on Harmonization guidelines with regards to precision, accuracy, sensitivity, selectivity, linearity, range, limit of detection, limit of quantification, reproducibility, recovery, carry-over and stability. Media from Helicobacter pylori cultures and faecal samples from human and different normo- and hypertensive rat strains were analysed. Data analysis was performed with Analyst® Software (version 1.5.2) and multiple t-test and Kruskal Wallis test using GraphPad Prism 8 software. Results and Discussion: The calibration curves of tested cardiotonic steroids were linear over a concentration range of 0.1-40 ng/mL with coefficients of determination greater than 0.990 except for telocinobufagin. The analytical method was selective with an estimated limit of detection and limit of quantification between 0.02-0.5 ng/mL and 0.1-2 ng/mL respectively. All tested cardiotonic steroids showed good recovery of over 70%. Accuracy and precision were found to be within acceptable limits of 15% and 20% at lowest limit of quantification for almost all the analytes and their stability in blood and solvent at room temperature, 4°C, -20°C and -80°C was tested for a month. Cardiotonic steroids were detected in Helicobacter pylori cultures and faecal samples with the exception of ouabain and proscillaridin A which were not detected at all. Although Helicobacter pylori were shown to produce cardiotonic steroids in vitro, no evidence of the effect of Helicobacter pylori on cardiotonic steroids production was detected in different normo- and hypertensive rat groups. Conclusion: The quantitative analytical method was successfully validated, over expected in vivo concentration ranges for 8 different cardiotonic steroids. The extraction and analytical methods were both successfully applied to Helicobacter pylori cultures and faecal rat samples where cardiotonic steroids were detected. / Dissertation (MSc)--University of Pretoria 2020. / National Research Foundation Student bursary / Pharmacology / MSc (Pharmacology) / Unrestricted

Yes / TOBI® is a recently marketed preservative and sulphate free tobramycin formulation approved by FDA for maintenance therapy for patient with cystic fibrosis. The performance of selected recent nebuliser delivery systems has been assessed using the developed method to determine the optimum combinations to deliver approved tobramycin inhaled solution (TOBI)®. A simple, sensitive and specific high performance liquid chromatographic method has been developed and used to quantitative determination of the aminoglycoside tobramycin following pre-column derivatisation with phenylisocyanate (PIC). The reaction time was 10 min at 80º C and the resulting derivative was stable for five days at room temperature. The quantitative performance of the assay was further improved by using another aminoglycoside (neomycin) as internal standard. The stable resulting PIC-tobramycin derivative was separated using a HPLC 5μm Columbus C18 column (150x4.60 mm i.d, Phenomenex). The mobile phase was consisted of acetonitrile-glacial acetic acid-water (450:5:545, v/v/v) and ultraviolet detection at (240 nm). The proposed method showed good validation data. The standard curve was linear (n=5) at seven different concentrations, ranging from 20 to 140μg/ml and the correlation coefficient (R2) of the regression line was 0.9995. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.86μg/ml and 2.62μg/ml, respectively. The relative standard deviation (RSD %) was less than 0.6% for intra-day assay (n=5) and 2.5% for inter-day assay (n=5). A number of nebuliser performance comparison studies have been demonstrated for aerosolise TOBI® to choice the optimum combination produces high repirable inhaled mass of tobramycin. The objective of this study was to evaluate the performance of recent nebuliser delivery systems to nebulise approved tobramycin inhaled solution (TOBI)®.

This dissertation describes the elucidation and implementation of derivatisation in the quantification of biologically active vitamin D metabolites in limited volume serum and dry blood spot samples (DBS) using the liquid chromatography tandem-mass spectrometry (LC-MS/MS) analytical technique. This manuscript describes in detail the development and validation of an analytical methodology, highlighting the role derivatisation and mass spectrometry plays in the structural characterisation and quantification of vitamin D metabolites. The first chapter reviews comprehensively, the history of vitamin D biosynthesis discovery as an anti-rickets agent, the biochemistry of vitamin D, its metabolic pathway, functions in the different biological systems and the consequences of its deficiency in the body. The second chapter reviews the current methods and techniques utilised for the detection and characterization of vitamin D metabolites, with specific emphasis based on the contribution made by derivatisation and mass spectrometry. A brief introduction to derivatisation is provided, with specific focus on PTAD and Amplifex diene reagents (Cooksontype reagents) used in this study. The importance of sensitivity and selectivity of targeted analytes is described first in detail for underivatised analytes, followed by PTAD and Amplifex derivatised samples. Chapter 2 also describes the importance of vitamin D quantification using liquid chromatography, the strengths and limitations of LC-MS/MS when used in isolation and after derivatisation. Also discussed, is how combining these techniques can overcome inherent limitations in LCMS/MS and enhance analytical performance. In Chapter 3 the materials and methods used and the study design is laid out, describing a brief introduction of the routinely used clinical diagnostics assay enzyme-linked immunosorbent assay (ELISA) as a reference method and is compared to an LC-MS/MS assay, to ascertain discrepancies and agreement between both methodologies from the same volunteer samples. Chapters 3 and 4 describes the comprehensive development, optimisation and validation of the highly sensitive PTAD derivatives LC-MS/MS assay for the quantification of active vitamin D metabolites, as well as the development of method using Amplifex diene derivatisation. Also discussed, is sample preparation optimisation of DBS and Mitra micro-samples. A holistic approach was taken to the development of the methodologies to provide data from which the required analytical information can be obtained for method evaluation and statistical analysis. The validated PTAD derivatives method is applied to the quantification of vitamin D metabolites in limited volume (100 μL) clinical human serum samples from 30 volunteers compared to results obtained using the clinical diagnostics ELISA technique. In Chapter 4 data analysis is described and the results are further discussed and a conclusion made based on the findings from the study. This study envisaged that combination of limited sample volume and DBS, derivatisation and LCMS/ MS is a powerful tool in vitamin D metabolite analysis and provided evidence of a positive increase in sensitivity and selectivity between derivatised compared to underivatised samples. A 10-fold increase in signal-to-noise-ratio (S/N) was observed when comparing PTAD derivatised, and Amplifex diene derivatised versus underivatised samples. Chapter 5 presents suggested future directions and considerations in the areas of vitamin D metabolite derivatisation and DBS sampling technique analysis using LC-MS/MS research based on the results presented in this dissertation. / Dissertation (MSc)--University of Pretoria, 2017. / Pharmacology / MSc / Unrestricted

The aim of this diploma thesis was to develop a miniaturized extraction method for a fast screening of non-volatile nitroso compounds using gas chromatography with a nitroso specific chemiluminescence detection. According to a final methodology, the samples were prepared by extraction of grinded malt using a mixture of pyridine and acetonitrile in ratio 60:40 (v/v). To enhance volatility of the determined analytes, the two-step derivatization using hexamethyldisalazane and N,O-bis(trimethyl)-trifluoroacetamide was used. The total volume of the sample was 200 l and the preparation time after optimization was in total 80 min. The extraction method was connected to a classification method, which can divide chromatographic peaks into the groups of N-nitroso and C-nitroso compounds, and interfering substances. After application of the methods mentioned above to real malt samples, the specific chromatographic peaks of C-nitroso and N-nitroso compounds were selected. Description of their properties and structure suggestion will be a subject of the following study. Keywords Nitroso compounds, malt, extraction, derivatization, gas chromatography, chemiluminescence detector

Au cours de ce travail de thèse intitulé " Identification chimique de métabolites secondaires de certains microorganismes, évaluation de leurs effets dans les domaines pharmaceutiques et agronomiques ", nous nous sommes intéressés à l'étude des effets des conditions de culture sur la production des composés organiques volatils microbiens à partir de deux souches bactériennes co-existantes dans le sol Français : Burkholderia sp. et Bacillus megaterium. A partir des différents extraits préparés, plus que cent composés ont été identifiés, comprenant les dicétopipérazines, les alcools, les composés soufrés, les esters et les acides carboxyliques, par le biais de plusieurs techniques chimiques, analytiques et spectroscopiques. Les résultats obtenus ont montré que les conditions de culture sont les pricipales responsables de la production des différentes familles chimiques des volatiles. Nous avons identifiés des composés qui sont rapportés pour la première fois à partir des bactéries tel que: la N-butylbenzènesulfonamide, triacontane, le proponaoate de 3- (3,5-di-tert-butyl-4-hydroxyphényl), (E) -5-chloro-3-(hydroxyimino) indoline-2-one et 1,3,5-triméthyl-2-octadecylcyclohexane. Sur le plan biologique, on a montré que les résultats obtenus sont fortement influencés par les conditions de culture utilisées pour cultiver les bactéries testées. En parallèle à cette investigation, nous avons montré que les extraits de Burkholderia sp. sont dotés d'un très important potentiel allélopathique. Enfin, une série des analogues de dicétopipérazines a été préparée et évaluée pour leurs activités anti-xanthine oxydase, anti a-amylase et anti 5-lipoxygénase ainsi que pour leurs activités cytotoxiques contre les lignées cellulaires suivantes ; OVCAR, MCF7 et HCT116. Un certain nombre de ces dérivés de dicétopiperazine ont montré des activités anti a-amylase et cytotoxique importantes. / In this thesis entitled " Chemical identification of secondary metabolites from microorganism, evaluation of their effects on pharmaceutical and agronomic fields ", we are interested in studying the effect of culture conditions on the production of microbial volatiles organic compounds by two bacteria that inhabit French soil which are: Burkholderia sp. and Bacillus megaterium. From different prepared extracts, more than one hundred compounds were identified, including diketopiperazine, alcohols, sulfur containing compounds, esters and carboxylic acids, by means of several chemical, analytical and spectroscopic techniques. Results showed that culture conditions of different bacteria are the mainly responsible of production of different blend of volatiles. Many identified compounds including N-butylbenzenesulfonamide, triacontane, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate, (E)-5-chloro-3-(hydroxyimino)indolin-2-one and 1,3,5-trimethyl-2-octadecylcyclohexane are reported for the first time from bacteria.Biologically, we have shown that obtained results are greatly influenced by the cultures conditions used in cultivation of tested bacteria. In addition to that, we have shown that Burkholderia sp. extracts possessed a very good allelopathic potential. Finally, a series new protested deketopiperazine derivatives have been prepared and evaluated in vitro against xanthine oxidase, a-amylase and 5-lipoxygenase enzymes, OVCAR, MCF7 and HCT116 cancer cell lines. Some of these molecules have been shown to be potent inhibitors of a-amylase and different cancer cell lines.