<p>U okviru doktorske disertacije su razvijeni i optimizovani postupci pripreme uzoraka hrane (žitarica, sirovina, poluproizvoda i prehrambenih proizvoda na bazi žitarica, voća i povrća) i stočne hrane, kao i simultano određivanje tropanskih i glikoalkaloida primenom gasne i tečne hromatografije uz maseno-spektrometrijsku detekciju. Razdvajanje alkaloida primenom gasne hromatografije je izvedeno na kapilarnoj koloni (HP-5MS UI), uz detekciju sa kvadrupolnom masenom spektrometrijom SIM tehnikom, u intervalu m/z 50&ndash;550 a.m.u. Pri optimizovanim uslovima postignuto je razdvajanje homatropina, atropina i skopolamina u vremenu od 12.75 min, pri čemu<br />tropin i anisodamin nisu mogli biti detektovani. Glikoalkaloidi nisu direktno mogli biti određivani gasnom hromatografijom usled njihove visoke molekulske mase i male isparljivosti. Za simultano određivanje tropanskih alkaloida (tropin, l-hiosciamin, atropin, skopolamin, homatropin i anisodamin) i glikoalkaloida (&alpha;-solanin i &alpha;-kakonin) validirana je brza i osetljiva multirezidualna LC&ndash;MS/MS metoda. Kori&scaron;ćena je disperzivna čvrsto-fazna ekstrakcija sa 0.5% mravlje kiseline u acotonitrilu/vodi (75:25, v/v), solima magnezijum sulfat, natrijum hlorid i natrijum citrat kao i C₁₈ sorbent. Analiti su razdvojeni na Chirobiotic V koloni, sa mobilnom fazom sastavljenom od 10 mM amonijum formata u voda/acetonitril (90:10, v/v) i metanol/acetonitril (50:50, v/v), me&scaron;anim u odnosu 20:80 (v/v). Detekcija komponenti je izvedena u pozitivnom elektrosprej modu (ESI+), kori&scaron;ćenjem reakcionog vi&scaron;estrukog monitoring akvizacionog moda (MRM). Optimizovana tečno hromatografska metoda je podrazumevala brz i jednostavan proces ekstrakcije, sa prinosom od 61-111% za pojedine alkaloide, dobru linearnost u &scaron;irokom opsegu (5-80 &mu;g/kg, r²=0.998), dobru selektivnost, robusnost i preciznost (CV &lt; 5%). Granica detekcije (LOD) za sve alkaloide je bila u opsegu od 0.74 do 0.79 ng/g dok se granica kvantifikacije (LOQ) kretala od 2.17 do 2.46 ng/g u svim žitaricama, izuzev za tropin u soji i lanenom semenu (LOD = 1.55 i LOQ = 4.91 ng/g). Pri analizi uzoraka sa trži&scaron;ta alkaloidi nisu detektovani u analiziranim uzorcima hrane, kao &scaron;to su: p&scaron;enica, raž, kukuruz, bra&scaron;no od me&scaron;anih žitarica, kukuruzno bra&scaron;no, biskvit i krekeri. Stočna hrana namenjena ishrani svinja i peradi je sadržala atropin, skopolamin, &alpha;-solanin i &alpha;-kakonin u koncentracionom opsegu od 3.6 do 21.7 ng/g. Atropin i skopolamin su detektovani u koncentracionom opsegu od 2.8 do 9.8 ng/g u hrani namenjenoj ishrani krava i zečeva, dok u hrani nemenjenoj ishrani konja i divljih životinja alkaloidi nisu detektovani. U analiziranim uzorcima voća i povrća (jabuka, kru&scaron;ka, avokado, mrkva, krastvac i paprika) po prvi put u ovom radu su detektovani glikoalkaloidi, &alpha;-solanin i &alpha;-kakonin. Koncentracija oba glikoalkaloida se kretala u opsegu od 0.3 do 15 ng/g. Sadržaj glikoalkaloida u krompiru i čipsu (8708.9-18794.7 ng/g) se nalazio u okviru preporučenog ukupnog sadržaja glikoalkaloida od 200 mg/kg (sirova odvaga) (FAO/WHO, 1999). Apsorpcija i translokacija alkaloida od strane p&scaron;enice u koren, listove i stabljiku je ustanovljena upotrebom atropina ¹⁴C. Utvrđeno je da biljka nakon 15 dana apsorbuje 4.30% i 2.28% atropina ¹⁴C za niži (13676 dpm/g soil) i vi&scaron;i (37203 dpm/g soil) sadržaj standarda sa kojim je zemlji&scaron;te spajkovano, redom. Količina apsorbovanog atropina se smanjivala tokom rasta biljke. Biljka starosti 90 dana je apsorbovala 0.38% i 0.21% atropina ¹⁴C za niži i vi&scaron;i sadržaj standarda, redom. Povećanje koncentracije supstance u zemlji&scaron;tu nije uticalo na dalje povećanje apsorpcije. Do nagomilavanja supstance je do&scaron;lo u listovima (83%) dok su niže koncentracije zabilježene u korenu (8.6%), stabljici (4.2%) i semenu (4.1%). U analiziranim uzorcima vode, koja je poticala od ispiranja zemlji&scaron;ta obogaćenog atropinom ¹⁴C, nakon 30 dana supstanca je detektovana u koncentraciji od 0.5%. Tokom vremena je ustanovljeno smanjenje ispiranja ove supstance (0.01% nakon 90 dana). Analiza uzoraka zemlji&scaron;ta nakon 30 i 60 dana je pokazala značajne adsorpcione osobine atropina, tako da je količina čvrsto adsorbovanog (neekstrahovanog) atropina iznosila 60% i 70%, redom. Zaostali atropin je bio stabilan i nakon 90 dana.</p> / <p>The methods of sample preparation have been developed and optimized for food (grains, raw materials, food products based on grains and fruits and vegetables) and feed analyses for the purpose of simultaneous determination of tropane and glycoalkaloids by gas and liquid chromatography hyphenated to mass spectrometry. Separation of alkaloids by gas chromatography was achieved by using capillary column HP-5MS UI. The alkaloids have been detected by using a quadrupole mass spectrometer inSIM mode for the range of m/z 50&ndash;550 a.m.u. Under optimised conditions, good separation of homatropine, atropine and scopolamine was achieved after 12.75 min, while tropine and anisodamine couldn`t be detected. Glycoalkaloids could not be analysed directly by gas chromatography due to their high molecular weight and low volatility. For simultaneous determination of tropane alkaloids (tropine, atropine, scopolamine, homatropine, anisodamine) and glycoalkaloids (&alpha;-solanine, &alpha;-chaconine) fast and sensitive multiresidue LC&ndash;MS/MS method was validated. In sample preparation dispersive solid phase extraction (DSPE) was performed with 0.5% formic acid in acetonitrile/water (75:25, v/v) and a mixture of magnesium sulphate, sodium chloride, sodium citrate and C18 sorbent. The analytes were separated by isocratic HPLC on a Chirobiotic V column with the mobile phase that consisted of 10 mM ammonium formate in water/acetonitrile (90:10, v/v) and methanol/acetonitrile (50:50, v/v), mixed in the ratio of 20:80 (v/v).<br />Compounds were detected in positive electrospray ionization mode (ESI+), using multi reaction monitoring (MRM). Optimised liquid-chromatographic method exhibited good linearity in the range 5-80 ng/g (r²=0.998). The method has shown to be specific, selective, accurate (recoveries from 61- 111%), precise (CV &lt; 5%) and rugged. Calculated limits of detection (LOD) for all alkaloids were in the range 0.74-0.79 ng/g, while the limits of quantitation (LOQ) were in the range 2.2-4.9 ng/g in all grains, except for tropine in soybean and linseed (LOD = 1.55 and LOQ = 4.91 ng/g). The proposed method was applied in the analyses of samples obtained from local supermarkets. The alkaloids were not detected in following food samples:<br />wheat, rye, maize, mixed grain flour, corn flour, biscuits and crackers. The feeds for pigs and chicken were the most contaminated with atropine, scopolamine, &alpha;-solanine and &alpha;-chaconine with the contents of alkaloids in the range of 3.6 to 21.7 ng/g. Atropine and scopolamine were detected in cattle and rabbit feed in concentrations ranging from 2.8 to 9.8 ng/g, while in feed for horses and wild animals none of the target alkaloids were detected. Conducted research reports for the first time the presence of glycoalkaloids, &alpha;-solanine and &alpha;-chaconine in fruit and vegetable samples (apple, pear, avocado, carrot, cucumber and paprika). The concentrations of these alkaloids were in the range of 0.3 to 15 ng/g. The content of glycoalkaloids in potato and chips complied with the recommended content of total glycoalkaloids concentration of 200 mg/kg (raw weight) (FAO/WHO, 1999). Absorption and translocation of alkaloids in wheat (roots, leaves, stem) was determined by using atropine ¹⁴C. It was found that young wheat after 15 days absorbed approximately 4.30% and 2.28% of atropine ¹⁴C for low (13676 dpm/g soil) and high (37203 dpm/g soil) spiked levels in soil, respectively. Increase in the spiked concentration in the soil did not affect higher absorption of atropine ¹⁴C in wheat. The highest accumulation of atropine ¹⁴C was observed in the leaves (83%) while lower<br />concentrations were detected in the roots (8.6%), stems (4.2%) and seeds (4.1%). In collected water samples during the soil leaching, atropine ¹⁴C was detected in the concentration of 0.5%. Leaching decreased with the time (0.01% after 90 days). Analyses of soil samples after 30 and 60 days showed strong adsorption of atropine to the soil and quantity of adsorbed atropine was 60% and 70%, respectively. Adsorbed atropine in the soil was stable after 90 days.</p>

Neste trabalho são apresentados os ensaios realizados para a caracterização da cultura de Rauvolfia sellowii Müll. Arg. (Apocynaceae). Foram determinados os parâmetros: pH, peso fresco, peso seco, produção de alcalóides, e consumo de açúcares. A curva de crescimento foi similar às observadas para as culturas de células de outras espécies, estendendo-se até o dia 14. As culturas de R. sellowii não converteram a sacarose em glicose e frutose no meio de cultura. A sacarose foi absorvida diretamente do meio. A absorção completou-se no dia 22. Não houve mudança significativa no pH do meio durante o desenvolvimento celular. A vomilenina foi identificada como o alcalóide majoritário. As alterações na produção deste alcalóide foram avaliadas pela modificações nas condições de cultivo, supressão de auxinas, aumento da concentração de sacarose e mio-inositol, adição de extrato de levedura (eliciador biótico), e adição dos precursores triptofano e triptamina. Em todos os casos houve a supressão da produção de vomilenina. Com exceção da adição de precursores, os tratamentos provocaram o acúmulo de substâncias desconhecidas, possivelmente outros alcalóides. / This work aimed to characterize the growth parameters of a Rauvolfia sellowii Müll. Arg. (Apocynaceae) cell suspension culture. The parameters analyzed were pH variation, biomass accumulation (fresh weight and dry weight), production of alkaloids and sugars uptake. The growth curve was similar to that observed for other plant cells, the culture cycle lasted for 14 days. R. sellowii cultures did not converted sucrose into glucose and fructose in the culture medium. Sucrose was directly taken up from the medium. The complete uptake occurred at day 22. There were no significant changes in the medium pH during the cell development. The major alkaloid accumulated in the cultures was characterized as the vomilenine. The regulation of vomilenine production was also evaluated by changing the culture conditions: depletion of auxins, increase of sucrose and myo-inositol concentration, addition elicitor (yeast extract) and precursor feeding (tryptophan and tryptamine). In all the conditions tested, vomilenine production was suppressed. Moreover, with the exception of precursor feeding, all treatments caused the accumulation of unknown substances, possibly alkaloids.

O maracujá azedo, Passiflora edulis, e o maracujá doce, Passiflora alata, são as duas espécies pertencentes à família Passifloraceae de maior importância econômica para o Brasil, sendo seus frutos amplamente comercializados como alimentos. Um grupo de substâncias conhecido como alcaloides &beta;-carbolínicos são componentes minoritários desses frutos, no entanto, a literatura indica que substâncias pertencentes a esse grupo podem ter atividade tóxica. Este trabalho apresentou três objetivos específicos, com o intuito de ampliar o conhecimento sobre a fitoquímica dos frutos de P. edulis e de P. alata e da aplicação da SBSE como método de preparo de amostra: quantificação de harmana e de harmina na polpa e nas sementes de P. alata utilizando SBSE-PDMS e análise por HPLC/Flu; identificação de alcaloides &beta;-carbolínicos nas cascas de P. edulis através de análises por HPLC/Flu e por UHPLC/MS; estudo do processo de extração de norharmana por SBSE com duas fases extratores diferentes (PDMS e EG-Silicone) por HPLC/Flu. A quantificação de harmana e harmina na polpa e nas sementes de P. alata foi realizada após preparo de amostra por SBSE-PDMS e análises por HPLC/Flu. A concentração de harmana encontrada foi 1,0328 . 10-1 ± 3,1217 . 10-3 &mu;g L-1 na polpa, enquanto que nas sementes foi encontrada a concentração de 7,4391 . 10-5 ± 2,5501 . 10-6 &mu;g g-1. As concentrações de harmina ficaram abaixo do LOD e do LOQ na polpa e nas sementes de P. alata, respectivamente. Na identificação dos alcaloides &beta;-carbolínicos nas cascas de P. edulis, os extratos para análises por HPLC/Flu e por UHPLC/MS foram preparados pelo método clássico, sendo identificados os alcaloides norharmana, harmana, harmina, harmol e harmalol. Nas análises por HPLC/Flu de extrato das cascas de P. edulis preparado utilizando SBSE-PDMS, o alcaloide norharmana foi identificado como majoritário e por esse motivo, foi realizado o estudo do processo de extração de norharmana por SBSE com duas fases extratoras diferentes, PDMS e EG-Silicone, utilizando planejamento fatorial fracionário, tendo como objetivo obter a melhor recuperação percentual possível. Com as melhores condições para extração definidas, os ensaios utilizando PDMS e EG-Silicone apresentaram recuperação percentual de cerca de 50 % e 80 %, respectivamente. A quantificação de harmana na polpa e nas sementes do maracujá doce, P. alata, indicou quantidades muito pequenas desse alcaloide nessas partes dos frutos, levando à conclusão que um fruto de P. alata, apresenta cerca de 140 vezes menos alcaloides &beta;-carbolínicos do que o fruto de P. edulis, levando em consideração as quantidades de harmana e harmina no maracujá azedo relatadas na literatura. A identificação dos alcaloides &beta;-carbolínicos nas cascas de P. edulis é um importante passo para a compreensão sobre a fitoquímica dessa parte do fruto, que, nos últimos anos, deixou de ser apenas resíduo industrial e passou a ser produto alimentício com valor agregado, comercializadas como farinhas das cascas de maracujá. O estudo sobre a utilização da SBSE como técnica de extração de norharmana mostrou-se promissor, atingindo recuperação percentual aceitável para o futuro desenvolvimento de um método de quantificação de norharmana nas cascas de maracujá. / Sour passion fruit, Passiflora edulis, and sweet passion fruit, Passiflora alata, are the two species of Passifloraceae of greater economic importance to Brazil, and their fruits are widely marketed as food. A class of compounds known as &beta;-carboline alkaloids is a minor component of these fruits, however, the literature indicates that substances belonging to this group may have toxic activity. This work presents three specific objectives, in order to increase knowledge about the phytochemistry of P. edulis and P. alata and the application of SBSE as a sample preparation method: quantification of harmane and harmine in the pulp and in the seeds of P. alata using SBSE-PDMS and HPLC/Flu analysis; identification of &beta;-carboline alkaloids in P. edulis peels using HPLC/Flu and UHPLC/MS analysis; study of the SBSE extraction process of norharmane using two different phases (PDMS and EG-Silicone), by HPLC/Flu analysis. Quantification of harmane and harmine in the pulp and the seeds of P. alata was performed after sample preparation by SBSE-PDMS and analysis by HPLC/Flu. The concentration of harmane was 1,0328 . 10-1 ± 3,1217 . 10-3 &mu;g L-1 in the pulp while the in the seeds it was found 7.4391 . 10-5 ± 2.5501 . 10-6 &mu;g g-1 harmane. The concentrations of harmine were below the LOD and LOQ in the pulp and in the seeds of P. alata, respectively. For the identification of the &beta;-carboline alkaloids in the peels of P. edulis, the extracts were prepared by using the classic method and analyzed by HPLC/Flu and UHPLC/MS, and the alkaloids norharmane, harmane, harmine, harmol and harmalol were identified. In the HPLC/Flu analysis of the extract of P. edulis peels prepared using SBSE-PDMS, the alkaloid norharmane was identified as a major constituent and, for this reason, it was performed a study about the extraction process of norharmane by SBSE, evaluating two different phases, PDMS and EG-Silicone, by using fractional factorial design, aiming to get the best percentage recovery. Defined the best conditions for extraction, the experiments performed by using PDMS and EG-Silicone bars showed percentage recovery about 50% and 80%, respectively. Quantification of harmane in the pulp and seeds of sweet passionfruit, P. alata, indicated very small amounts of this alkaloid in these parts of the fruits, leading to the conclusion that the fruits of P. alata, has around 140 times less &beta;-carboline alkaloid than the fruits of P. edulis, taking into account the amounts of harmana and harmine on sour passionfruit reported in the literature. Identification of &beta;-carboline alkaloids in P. edulis peels is an important step for understanding the phytochemistry of this part of the fruits, which, in recent years, is no longer just an industrial waste and became a food product with added value, marketed as passion fruit peels flour. The study about the utilization of SBSE as extraction technique of norharmane showed to be promising, reaching acceptable recovery percentage, for the future development of a method for quantification of norharmane in passion fruit peels.

1 9 ABSTRACT Jurkaninová, M.: Vinca minor L. alkaloids and their biological activity I. Diploma thesis, Charles University, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Botany, Hradec Králové, 2019 The aim of this thesis was the isolation of alkaloids from selected fraction 3 (joined fractions (15 - 36), which was a sub-fraction of the fraction VM 323 - 327. It was obtained from the previous processing of an alkaloidal extract from the Vinca minor L at the Department of Pharmaceutical Botany as a part of elaboration of diploma thesis of Aneta Vítavcová.[78] The fraction VM 323-327 was separated by column chromatography on silica gel and a totally, of 7 subfractions were obtained. Subsequent repeated processing of the selected sub-fraction 3 (15 - 36) by preparative TLC on silica gel resulted in the isolation of (-)-vinoxine and its racemate (±)-vinoxine. Identification of their structure was determined based on MS, NMR and optical rotation. The inhibitory activity against acetylcholinesterase, butyrylcholiesterase and prolyl oligopeptidase were determined for the isolated substances. Inhibitory activity against selected enzymes was measured by spectrophotometric methods. Isolated alkaloids were required to be inactive against AChE and POP (IC50 >1000 μM), against to BChE showed a...

Abstract not available

Irradiation of a tryptamine linked through its side-chain nitrogen to an alkylidene malonate residue results in an intramolecular [2 + 2] cycloaddition to the indole 2,3-double bond. The resultant cyclobutane undergoes spontaneous retro-Mannich fission to produce a spiro[indoline-3,3-pyrrolenine] with relative configuration defined by the orientation of substituents in the transient cyclobutane. The novel tandem intramolecular photocycloaddition- retro-Mannich (TIPCARM) sequence leads to a spiropyrrolidine which is poised to undergo a second retro-Mannich fragmentation [TIPCA(RM)₂] that expels the malonate unit present in the photo substrate and generates transiently an indolenine. The indolenine undergoes rearrangement to a β-carboline which can undergo further rearrangement under oxidizing conditions to an oxindole. Three oxindole natural products, coerulescine, horsfiline and elacomine, were synthesized using this strategy. The TIPCARM strategy was extended to an approach that would encompass the Vinca alkaloids vindorosine and minovine. In this case, the TIPCARM sequence was followed by an intramolecular cyclization that provided tetracyclic ketone 5.86 containing rings A, B, C and D of vindorosine. A tetracyclic intermediate was synthesized which could also provided access to the Vinca alkaloid minovine. / Graduation date: 2012

The large pine weevil, Hylobius abietis L., is a major insect pest on conifer seedlings in northern Europe. Due to its feeding newly planted trees get girdled, resulting in high seedling mortality (up to 80%). As a consequence great financial losses to the forest industry occur. Today the seedlings are protected with the pyrethroid insecticide cypermethrin. This insecticide is toxic to aquatic organisms and is, from 2010, prohibited for use in Sweden by the Swedish Chemicals Inspectorate. An alternative to insecticides is to protect the seedlings with antifeedants, compounds that, either through taste or smell or both, deter the weevils from feeding. This thesis describes the search for and the synthesis of such antifeedant compounds. Bark extracts of several woody species, known to be non-palatable to the weevil, were prepared and found to display antifeedant activity against H. abietis. The major chemical constituents of the extracts were tested for antifeedant activity. Antifeedants such as eugenol, 2-phenylethanol and benzylalcohol, but also feeding stimulants such as β-sitosterol and linoleic acid, were identified. An extract of linden bark, Tilia cordata, was shown to contain nonanoic acid, a highly active antifeedant. Other aliphatic carboxylic acids were also found to display high antifeedant activities against the weevil, both in laboratory and in field tests. The enantiomers of dihydropinidine, a piperidine alkaloid present in several conifer species, were prepared by dimethylzinc mediated allylation of 2- methyltetrahydropyridine-N-oxide. When tested in micro feeding assays, no difference in antifeedant activity was found for the enantiomers. In a field test high antifeedant activity, comparable with that of the presently used insecticide cypermethrin, was found for (±)-dihydropindine. Other naturally occurring piperidine alkaloids were synthesised and also found to display high antifeedant activities in laboratory tests. Structure-activity relationships were evaluated for methoxy substituted benzaldehydes, benzoic acids and cinnamic aldehydes, -acids, -esters and -alcohols. While the carboxylic acids were inactive or even feeding stimulants, the aldehydes were the most active antifeedants / QC 20110124

Polycyclic nitrogen containing heterocycles form the basic skeleton of numerous alkaloids and physiologically active drugs. Alloyohimbane was obtained from 3,4-dihydro-â-carboline using an iron-mediated [2+2+1] cycloaddition as the key-step. The bis-TMS-diyne was conveniently obtained by the C-alkylation of 3,4-dihydro-â-carboline followed by N-alkylation. Demetalation of the iron-complex followed by hydrogenation, E-ring expansion, and reduction provided alloyohimbane, a structurally and biologically interesting substance, via a linear eight-step sequence in 7% overall yield based on 3,4-dihydro-â-carboline. Another sequence provided (±)-alloyohimbane and (±)-3-epi-alloyohimbane in nine steps. The pyrrole unit occurs in a variety of naturally occurring compounds, pharmaceutical products and polymers. A novel two-step procedure for the synthesis of pyrroles by addition of a propargyl Grignard reagent to a Schiff base and subsequent silver(I)-promoted oxidative cyclization of the resulting homopropargylamine has been developed. The generality of this reaction was proven by the synthesis of a broad variety of substituted pyrroles using silver(I)-promoted cyclization. A three-step synthesis of (±)-harmicine, a natural product isolated from the Malaysian plant Kopsia griffithii having strong anti-leishmania activity, from 3,4-dihydro-â-carboline is achieved by addition of 3-trimethylsilylpropargyl Grignard reagent, Ag(I)-promoted oxidative cyclization to a pyrrole, and chemoselective hydrogenation of pyrrole ring. Total synthesis of anti-tumor active crispine A and biologically active 1,2,3,5,6,10b-hexahydropyrrolo[2,1-a]isoquinoline have been achieved in three steps using silver(I)-promoted oxidative cyclization as key step.

<p>The large pine weevil, Hylobius abietis L., is a major insect pest on conifer seedlings in northern Europe. Due to its feeding newly planted trees get girdled, resulting in high seedling mortality (up to 80%). As a consequence great financial losses to the forest industry occur. Today the seedlings are protected with the pyrethroid insecticide cypermethrin. This insecticide is toxic to aquatic organisms and is, from 2010, prohibited for use in Sweden by the Swedish Chemicals Inspectorate. An alternative to insecticides is to protect the seedlings with antifeedants, compounds that, either through taste or smell or both, deter the weevils from feeding. This thesis describes the search for and the synthesis of such antifeedant compounds.</p><p>Bark extracts of several woody species, known to be non-palatable to the weevil, were prepared and found to display antifeedant activity against H. abietis. The major chemical constituents of the extracts were tested for antifeedant activity. Antifeedants such as eugenol, 2-phenylethanol and benzylalcohol, but also feeding stimulants such as β-sitosterol and linoleic acid, were identified. An extract of linden bark, Tilia cordata, was shown to contain nonanoic acid, a highly active antifeedant. Other aliphatic carboxylic acids were also found to display high antifeedant activities against the weevil, both in laboratory and in field tests.</p><p>The enantiomers of dihydropinidine, a piperidine alkaloid present in several conifer species, were prepared by dimethylzinc mediated allylation of 2- methyltetrahydropyridine-N-oxide. When tested in micro feeding assays, no difference in antifeedant activity was found for the enantiomers. In a field test high antifeedant activity, comparable with that of the presently used insecticide cypermethrin, was found for (±)-dihydropindine. Other naturally occurring piperidine alkaloids were synthesised and also found to display high antifeedant activities in laboratory tests.</p><p>Structure-activity relationships were evaluated for methoxy substituted benzaldehydes, benzoic acids and cinnamic aldehydes, -acids, -esters and -alcohols. While the carboxylic acids were inactive or even feeding stimulants, the aldehydes were the most active antifeedants</p>

Despite decades of intense research, malaria remains a deadly worldwide disease. Resistance of Plasmodium falciparum to chemical treatment still remains important. Efforts are now being directed towards the discovery and development of new chemically diverse anti-malarial agents. In the course of the search for new antimalarial compounds, a study of plants traditionally used against malaria by the people inhabiting the forests located near Bhubaneswar, Orissa, India was made, which permitted the identification of 34 plants currently used. Among these, 27 plants were selected for testing for antiplasmodial activity aimed at identifying the most effective plants for further research. Also, their activities were compared with 27 randomly collected plant species in order to asess the value of an ethno-medical approach.