Distribution and oxidative activities of phenolic compounds in the plant kingdom

Plant phenolics have been studied for decades because of their role as chemodefensive compounds against herbivores and pathogens, and their assumed health benefits to humans. One of their proposed modes of actions is oxidation, which can happen enzymatically or spontaneously at alkaline conditions. An underlying issue is that the majority of studies only focus on one or few plant species or families, so gaining a comprehensive overview of the distribution of phenolics across the plant kingdom requires compiling data from several studies which may utilize fundamentally different extraction and analytical methods and have different research foci. This thesis has two parts. First, an existing analytical method was improved with an addition of a simple in planta enzymatic oxidation step. Thereby a single analytical procedure results in three types of data: the phenolic profile of the oxidized and non-oxidized plant samples as well as the alkaline and enzymatic oxidative activity of the individual compounds as well as the raw extract. Analyzing hundreds of samples revealed that at alkaline conditions, the most active compounds either contained a pyrogallol moiety or a catechol moiety at the end of an alkane chain. While enzymatic oxidation tended to favor compounds with a catechol moiety, the activity varied between plant species and even between tissues within the same species. In addition, a method for estimating the prevailing pH in larval gut was developed by studying the isomerization of caffeoylquinic acids at alkaline pH and comparing the results to the existing data of the isomer ratios in larval frass. Second, a research gap in the field of composition and ecology of the phenolics of tropical plants was covered in a large-scale screening study. Several predictions inspired by theories and hypotheses on plant apparency as well as resource availability and allocation were confirmed. For example, there was a strong positive correlation between seed mass and polyphenol content. The majority of seeds containing phenolics were rich in either various hydrolysable tannins or proanthocyanidins.Kasvikunnan fenolisten yhdisteiden esiintyvyys jahapettumisaktiivisuus Kasvien fenolisia yhdisteitä on tutkittu vuosikymmeniä, koska ne toimivat kemiallisena puolustuskeinona kasvinsyöjiä ja taudinaiheuttajia vastaan, minkä lisäksi niiden uskotaan olevan hyödyllisiä ihmisten terveydelle. Entsyymien katalysoiman sekä emäksisissä olosuhteissa tapahtuvan spontaanin hapettumisen on esitetty olevan eräs niiden toimintamuodoista. Valtaosa tutkimuksista keskittyy vain yhteen tai korkeintaan muutamaan kasvilajiin tai -heimoon, joten kattavan kokonaiskuvan saaminen edellyttää useiden tutkimustulosten koostamista siitäkin huolimatta, että mahdollisesti eri tavoitteisiin tähtäävissä tutkimuksissa on voitu käyttää oleellisesti erilaisia uutto- ja analyysimenetelmiä. Tämä väitöskirjatyö on kaksiosainen. Ensimmäisessä osassa olemassa olevaan analyysimenetelmään lisättiin yksinkertainen vaihe, jossa fenoliset yhdisteet hapetetaan itse kasvinäytteessä. Yhdellä analyysikerralla saadaan näin kerättyä kolmenlaista dataa: hapetettujen ja hapettamattoman näytteen sisältämät fenoliset yhdisteet sekä yksittäisten yhdisteiden ja raakauutteen emäksinen ja entsymaattinen hapettumisaktiivisuus. Satojen kasvinäytteiden analysointi osoitti, että emäksisissä olosuhteissa aktiivisimmat yhdisteet sisältävät joko pyrogallooliryhmän tai tyydyttyneen hiilivetyketjun päähän sitoutuneen katekoliryhmän. Katekoliryhmän sisältävät yhdisteet olivat niin ikään altteimpia hapettumaan entsymaattisesti, mutta hapettumisaktiivisuus vaihteli eri kasvilajien ja jopa saman lajin kasvinosien välillä. Lisäksi tässä osassa kehitettiin menetelmä toukkien suolen vallitsevan pH:n arvioimiseksi tutkimalla kahveoyylikviinihappojen isomeroitumista toukkien suolen emäksisiä olosuhteita imitoivissa pH:issa ja vertaamalla tuloksia aiemmin kerättyyn tietoon kahveoyylikviinihappoisomeerien määrällisistä suhteista toukkien ulosteessa. Työn toisessa osassa tutkittiin trooppisten kasvilajien siemeniä. Trooppisten kasvien sisältämiä fenolisia yhdisteitä ja niiden ekologiaa ei ole aiemmin juurikaan tutkittu, varsinkaan tässä mittakaavassa. Monet kasvien näkyvyyteen sekä ravinteiden saatavuuteen ja kohdentamiseen perustuvista ennusteista saivat kokeista vahvistusta – esimerkiksi siementen painon ja polyfenolikoostumuksen välillä havaittiin vahva korrelaatio. Fenolisia yhdisteitä sisältävistä lajeista valtaosa sisälsi joko erityyppisiä hydrolysoituvia tanniineja tai proantosyanidiineja

Editorial : COVID-19: Challenges, opportunities and lessons for occupational health

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Hygroscopicity of Nucleated Nanoparticles in CLOUD 7 Experiments

We investigated hygroscopicity of nucleated nanoparticles derived from dimethylamine and α-pinene with sulfuric acid during CLOUD 7 (Cosmic Leaving OUtdoor Droplets) campaign at CERN. The hygroscopicity of nucleated nanoparticles from 10 to 20 nm in mobility diameter was measured with a nano tandem differential mobility analyzer (nano-TDMA). Here, we present preliminary results from the CLOUD 7 experiments

A systematic review of primary school class teachers views of mathematics teaching and learning

The current study aimed (1) to analyse teachers’ view profiles from positive to negative based on the analysis of influencing factors and (2) to investigate the most studied concepts and methods in this context. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines, we conducted a comprehensive review of 25 peer-reviewed articles published between January 2010 and December 2022. Our findings show a landscape in which concepts related to mathematics teaching and learning often intersect with other domains. Nevertheless, a distinction exists in the definition of the fundamental concept, with limited attention given to mathematics learning and the role of students in contrast to the focus on mathematics teaching and the role of teachers. Our research highlights the necessity of thorough exploration of the dynamic factors that influence these views and their associated outcomes, categorised as (A) mutual consistency, (B) weak consistency, and (C) inconsistency, each providing distinct implications for support needs. Additionally, from an ontological perspective on affect, many studies overlook the notion of 'view' as a state or trait characteristic, potentially leading to inappropriate method selection. Therefore, we propose recommendations for future research, advocating for methodological precision, expanded object exploration, dynamic profiling, and the inclusion of diverse teacher categories

Oxidatively Active Plant Phenolics Detected by UHPLC-DAD-MS after Enzymatic and Alkaline Oxidation

We developed a combination of methods to estimate the alkaline oxidative conditions of the midgut of insect larvae and to reveal the alkaline and enzymatic oxidative activities for individual phenolic compounds present in the larval host plants. First, we monitored the in vitro isomerization of 5-O-caffeoylquinic acid (5-CQA) into 3-CQA, 4-CQA and 5-CQA at pH 9.0-11.0. Then we calculated the isomer ratios of 3-CQA, 4-CQA and 5-CQA from the frass of eight species of insect herbivores fed on foliage containing 5-CQA. The isomer ratios suggested that the midgut pH of these larvae ranged from 9.4 to around 10.1. Second, we developed an in situ enzymatic oxidation method that enabled oxidation of phenolics in a frozen plant sample at 30 A degrees C by species- and tissue-specific enzymes. Then we measured the alkaline and enzymatic oxidative activities of the individual phenolics in 20 plant species by quantifying the proportion of the compound concentration lost due to the auto-oxidation of a plant extract at pH 10 and due to the enzymatic oxidation of the frozen plant sample at 30 A degrees C. Our results showed that both of the oxidative activity types depended primarily on the type of phenolic compound, but the enzymatic oxidative activity depended also on the plant species and tissue type. This combination of methods offers an approach to characterize a wide array of phenolics that are susceptible to oxidation by the plant enzymes and/or by the alkaline conditions estimated to prevail in the insect midgut. We propose that these kinds of compound-specific results could guide future studies on specific plant-herbivore interactions to focus on the phenolics that are likely to be active rather than inactive plant phenolics

Distribution of enzymatic and alkaline oxidative activities of phenolic compounds in plants

In this study, we screened 287 plant tissue samples from 175 plant species for their phenolic profiles. The samples were oxidized enzymatically in planta or at high pH in vitro to determine how these two oxidative conditions would alter the initial polyphenol profiles of the plant. Compounds that contained a pyrogallol or dihydrox-yphenethyl group were highly active at pH 10. Enzymatic oxidation favored compounds that contained a catechol group, whereas compounds containing a pyrogallol group or monohydroxysubstituted phenolic moieties at most were oxidized less frequently. This study gives a broad overview of the distribution and alkaline oxidative activities of water-soluble phenolic compounds in plants as well as the enzymatic oxidative activities of various plant tissues

Seed tannin composition of tropical plants

Seeds collected from trees, shrubs and lianas growing on Barro Colorado Island, Panama, were analyzed for their content of phenolic compounds, oxidative activities and protein precipitation capacities. Proanthocyanidins and hydrolysable tannins were detected in one-third of 189 studied species. The most oxidatively active group of species were the ones containing prodelphinidins and ellagitannins whereas the species that had the highest protein precipitation capacity in relation to their total phenolics were the ones containing punicalagin. In addition, the oxidative activity and relative protein precipitation capacity were exceptionally high in the proanthocyanidin-rich genus Psychotria. This study offers a comprehensive overview on the tannin composition and the alkaline oxidative activities and protein precipitation capacities of the seeds of tropical plants

Seed tannin composition of tropical plants

Seeds collected from trees, shrubs and lianas growing on Barro Colorado Island, Panama, were analyzed for their content of phenolic compounds, oxidative activities and protein precipitation capacities. Proanthocyanidins and hydrolysable tannins were detected in one-third of 189 studied species. The most oxidatively active group of species were the ones containing prodelphinidins and ellagitannins whereas the species that had the highest protein precipitation capacity in relation to their total phenolics were the ones containing punicalagin. In addition, the oxidative activity and relative protein precipitation capacity were exceptionally high in the proanthocyanidin-rich genus Psychotria. This study offers a comprehensive overview on the tannin composition and the alkaline oxidative activities and protein precipitation capacities of the seeds of tropical plants

Accounting Problems Under the Excess Profits Tax

DNA vaccines based on subunits from pathogens have several advantages over other vaccine strategies. DNA vaccines can easily be modified, they show good safety profiles, are stable and inexpensive to produce, and the immune response can be focused to the antigen of interest. However, the immunogenicity of DNA vaccines which is generally quite low needs to be improved. Electroporation and co-delivery of genetically encoded immune adjuvants are two strategies aiming at increasing the efficacy of DNA vaccines. Here, we have examined whether targeting to antigen-presenting cells (APC) could increase the immune response to surface envelope glycoprotein (Env) gp120 from Human Immunodeficiency Virus type 1 (HIV- 1). To target APC, we utilized a homodimeric vaccine format denoted vaccibody, which enables covalent fusion of gp120 to molecules that can target APC. Two molecules were tested for their efficiency as targeting units: the antibody-derived single chain Fragment variable (scFv) specific for the major histocompatilibility complex (MHC) class II I-E molecules, and the CC chemokine ligand 3 (CCL3). The vaccines were delivered as DNA into muscle of mice with or without electroporation. Targeting of gp120 to MHC class II molecules induced antibodies that neutralized HIV-1 and that persisted for more than a year after one single immunization with electroporation. Targeting by CCL3 significantly increased the number of HIV-1 gp120-reactive CD8(+) T cells compared to non-targeted vaccines and gp120 delivered alone in the absence of electroporation. The data suggest that chemokines are promising molecular adjuvants because small amounts can attract immune cells and promote immune responses without advanced equipment such as electroporation.Funding Agencies|Research Council of Norway; Odd Fellow</p