Search results for "Arum"

2019

Phytochemical investigations of ethanol root bark and stem bark extracts of Cleistochlamys kirkii (Benth.) Oliv. (Annonaceae) yielded a new benzopyranyl cadinane-type sesquiterpene (cleistonol, 1) alongside 12 known compounds (2–13). The structures of the isolated compounds were established from NMR spectroscopic and mass spectrometric analyses. Structures of compounds 5 and 10 were further confirmed by single crystal X-ray crystallographic analyses, which also established their absolute stereochemical configuration. The ethanolic crude extract of C. kirkii root bark gave 72% inhibition against the chloroquine-sensitive 3D7-strain malaria parasite Plasmodium falciparum at 0.01 μg/mL. The is…

Medicinally Used Asarum Species: High-Resolution LC-MS Analysis of Aristolochic Acid Analogs and In vitro Toxicity Screening in HK-2 Cells

2017

Species of Asarum are used in traditional Chinese medicine and, similar to members of the genus Aristolochia, they contain aristolochic acid analogs (AAAs). These compounds are known for their nephrotoxic and carcinogenic effects. So far, the phytochemistry and nephrotoxicity of species of Asarum is not well studied. A high-resolution LC-MS-based metabolomic approach was used to study the phytochemical variation in medicinally used Asarum species. The cytotoxicity of the samples was assessed using human kidney (HK-2) cells. The majority of samples contained potentially nephrotoxic AAAs, including 9-methoxy aristolactam (AL) IV, AL I, and AL IV. These compounds were present in methanol as we…

Discovery of new antimalarial compounds by use of molecular connectivity techniques.

1999

Abstract Molecular connectivity has been applied to the search for new compounds with antimalarial activity. Linear discriminant analysis and connectivity functions were used to select several potentially suitable drugs which were tested for antimalarial properties by use of an in-vitro micro test which estimates parasite growth by measurement of incorporation of [3H]hypoxanthine. Hexetidine stands out among the compounds selected. Activity assays were performed with Plasmodium falciparum passou and 3CD7 strains, for which the IC50 values (doses resulting in 50% inhibition) were 320 and 400 ng mL−1 respectively. These results are comparable with those obtained for quinine chlorhydrate (IC50…

Dioncophyllines C2, D2, and F and related naphthylisoquinoline alkaloids from the Congolese liana Ancistrocladus ileboensis with potent activities ag…

2017

Dioncophylline F (1), the first 5,8'-coupled dioncophyllaceous alkaloid (i.e., lacking an oxygen function at C-6 and possessing an R-configuration at C-3), was isolated from the recently described Congolese liana Ancistrocladus ileboensis. Two further, likewise Dioncophyllaceae-type, alkaloids, the dioncophyllines C2 (2) and D2 (3), were identified, along with the Ancistrocladaceae-type compound ancistrocladisine B (4), which is oxygenated at C-6 and S-configured at C-3. The structures of the new compounds were determined by spectroscopic, chemical, and chiroptical methods. The stereostructure of 1 was further confirmed by total synthesis. As a consequence of the lack of a methyl group orth…

Survival strategies and pathogenicity of Ralstonia solanacearum phylotype II subjected to prolonged starvation in environmental water microcosms

2008

Survival strategies exhibited over 4 years by Ralstonia solanacearum phylotype (ph) II biovar (bv) 2 in environmental water microcosms were examined. The bacterium is a devastating phytopathogen whose ph II bv 2 causes bacterial wilt in solanaceous crops and ornamental plants. Outbreaks of the disease may originate from dissemination of the pathogen in watercourses, where it has to cope with prolonged nutrient limitation. To ascertain the effect of long-term starvation on survival and pathogenicity of R. solanacearum in natural water microcosms, survival experiments were conducted. Microcosms were prepared from different sterile river water samples, inoculated separately with two European s…

Nicotinamide Adenine Dinucleotide-Dependent and Nicotinamide Adenine Dinucleotide-Independent Lactate Dehydrogenases in Homofermentative and Heterofe…

1971

Three homofermentative ( Lactobacillus plantarum B38, L. plantarum B33, Pediococcus pentosaceus B30) and three heterofermentative ( Leuconostoc mesenteroides 39, L. oenos B70, Lactobacillus brevis ) lactic acid bacteria were examined for the presence or absence of nicotinamide adenine dinucleotide (NAD)-dependent and NAD-independent d - and l -lactate dehydrogenases. Two of the six strains investigated, P. pentosaceus and L. oenos , did not exhibit an NAD-independent enzyme activity capable of reducing dichlorophenol indophenol. The p H optima of the lactic dehydrogenases were determined. The NAD-dependent enzymes from homofermentative strains exhibited optima at p H 7.8 to 8.8, whereas va…

Piegādes ķēdes modelēšana izmantojot masu apkalpošanas sistēmas

2019

Darba tēma: Piegādes ķēdes modelēšana izmantojot masu apkalpošanas sistēmas Darba autors: Daniels Dāvis Ore Darbs ir veltīts, lai pētītu piegādes rindu ķēdes modeļus. Noteikt kādas ir teorētiskās iespējas un pielietojums, ja tiek aplūkotas ikdienā sastopamas masu apkalpošanas sistēmas. Darbā tiek aprakstīts mākslīgi izveidots piegādes ķēdes modelis. Darbā tiek apkopota teorija, kas paskaidro rindu sistēmu modeļus un kā noteikt dažādus sistēmas kvalitātes parametrus. Tiek aprakstīta programma Java Modeling Tools, kas ir paredzēta, lai analizētu rindu sistēmas veicot simulācijas. Izmantojot apkopoto informāciju, tiek praktiski noteikti un aprakstīti kvalitātes rādītāji mākslīgi izveidotajam m…

Dažādu kultivēšanas apstākļu ietekme uz Lactobacillus plantarum rezistenci pret oksidatīvo stresu

2020

Pienskābo baktēriju rezistence pret oksidatīvo stresu, kas cieši atkarīga no šūnu metabolisma, ir ļoti svarīga, lai tās varētu izmantot kā probiotikas. Darba mērķis bija novērtēt oksidatīvā stresa ietekmi uz L. plantarum kultūras enzimātisko aktivitāti pēc tās kultivēšanas dažādos apstākļos un aizsargvielu klātbūtnē. Oksidatīvā stresa ierosināšanai izmantots 1-2 mM H2O2 un 2-50 Gy jonizējošs starojums. Aizsargvielas – sulforafāns (SFA), sulforafēns (SFE). Salīdzinātas De Man, Rogosa and Sharpe (MRS) un Tryptone Soya Broth (TSB) barotnes. Barotnes sastāvs ietekmēja baktēriju augšanas kinētikas parametrus un reakciju uz oksidatīvo stresu. 1 μg/ml SFA vai SFE pievienošana kultūrām pirms apstar…

Origin of the natural variation in the storage of dietary carotenoids in freshwater amphipod crustaceans

2020

16 pages; International audience; Carotenoids are diverse lipophilic natural pigments which are stored in variable amounts by animals. Given the multiple biological functions of carotenoids, such variation may have strong implications in evolutionary biology. Crustaceans such as Gammarus amphipods store large amounts of these pigments and inter-population variation occurs. While differences in parasite selective pressure have been proposed to explain this variation, the contribution of other factors such as genetic differences in the gammarid ability to assimilate and/or store pigments, and the environmental availability of carotenoids cannot be dismissed. This study investigates the relati…

Prenylated Flavonoids from the Roots of Tephrosia rhodesica

2020

Five new compounds—rhodimer (1), rhodiflavan A (2), rhodiflavan B (3), rhodiflavan C (4), and rhodacarpin (5)—along with 16 known secondary metabolites, were isolated from the CH2Cl2–CH3OH (1:1) extract of the roots of Tephrosia rhodesica. They were identified by NMR spectroscopic, mass spectrometric, X-ray crystallographic, and ECD spectroscopic analyses. The crude extract and the isolated compounds 2–5, 9, 15, and 21 showed activity (100% at 10 μg and IC50 = 5–15 μM) against the chloroquine-sensitive (3D7) strain of Plasmodium falciparum. peerReviewed