Prenylated anthraquinones and other constituents from the seeds of Vismia laurentii

Two new prenylated anthraquinones, laurenquinone A (1) and B (2) were isolated from the seeds of Vismia laurentii together with four known compounds; xanthone V(1) (3), physcion (4), 3-geranyloxyemodin anthrone (5) and friedelin (6). The structures of the new metabolites were determined with the help of spectroscopic data including extensive 2D-NMR spectroscopy. The known compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature. Compounds 1, 4 and 5 exhibited moderate algicidal activity against Chlorella fusca and 3 showed moderate activity against the gram-positive bacterium Bacillus megaterium.     

Purification and Biochemical Characterization of Polyphenol Oxidases from Embryogenic and Nonembryogenic Cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.) Cells

Polyphenol oxidases (PPOs) were isolated from cell suspensions of two cultivars of cotton (Gossypium hirsutum L.), and their biochemical characteristics were studied. PPO from Coker 312, an embryogenic cultivar, showed a highest affinity to catechol 20 mM, and PPO from R405-2000, a nonembryogenic cultivar, showed a highest affinity to 4-methylcatechol 20 mM. The optimal pH for PPO activity was 7.0 and 6.0 for Coker 312 and R405-2000, respectively. The enzyme had an optimal temperature of 25 °C and was relatively stable at 20–30 °C. Reducing sodium metabisulfite, ascorbic acid, dithiothreitol, SnCl₂, and FeCl₃ markedly inhibited PPO activity, whereas its activity was highly enhanced by Mg²⁺, Ca²⁺, and Mn²⁺ and was moderately inhibited by Ba²⁺, Cu²⁺, and Zn²⁺. The analysis revealed a single band on the sodium dodecyl sulfate polyacrylamide gel electrophoresis which corresponded to a molecular weight of 55 kDa for Coker 312 and 42 kDa for R405-2000.     

A new time domain estimation of k-factors GARMA processes

We address the problem of parameter estimation of long memory time series. We consider k-factors Gegenbauer Autoregressive Moving Average (k-GARMA) processes and we estimate their parameters by the minimum Hellinger distance estimator. We establish the consistency of the estimator and the asymptotic normality for some bandwidth choice.     

Tramadol—A True Natural Product?

We have independently investigated the source of tramadol, a synthetic analgesic largely used for treating moderate to severe pain in humans, recently found in the roots of the Cameroonian medicinal plant, Nauclea latifolia. We found tramadol and its three major mammalian metabolites (O‐desmethyltramadol, N‐desmethyltramadol, and 4‐hydroxycyclohexyltramadol) in the roots of N. latifolia and five other plant species, and also in soil and local water bodies only in the Far North region of Cameroon. The off‐label administration of tramadol to cattle in this region leads to cross‐contamination of the soil and water through feces and urine containing parent tramadol as well as tramadol metabolites produced in the animals. These compounds can then be absorbed by the plant roots and also leached into the local water supplies. The presence of tramadol in roots is, thus, due to an anthropogenic contamination with the synthetic compound.     

Pycnangloside: a new cerebroside from bark of Pycnanthus angolensis

Pycnanthus anglonensis is known for its medicinal value. This paper deals with a phytochemical investigation of this species, from which pycnangloside (1), a new cerebroside has been isolated. Its structure was determined by comprehensive analyses of its 1D and 2D NMR spectroscopic, and ESI mass spectrometric data. Four known compounds were also isolated and identified as biochanin A, formonentin, beta-sitosterol, and beta-sitosterol glucopyranoside.     

Non-minimal and non-universal supersymmetry

I motivate and discuss non-minimal and non-universal models of supersymmetry and supergravity consistent with string unification at 10¹⁰ GeV.     

Tramadol—A True Natural Product?

We have independently investigated the source of tramadol, a synthetic analgesic largely used for treating moderate to severe pain in humans, recently found in the roots of the Cameroonian medicinal plant, Nauclea latifolia. We found tramadol and its three major mammalian metabolites (O‐desmethyltramadol, N‐desmethyltramadol, and 4‐hydroxycyclohexyltramadol) in the roots of N. latifolia and five other plant species, and also in soil and local water bodies only in the Far North region of Cameroon. The off‐label administration of tramadol to cattle in this region leads to cross‐contamination of the soil and water through feces and urine containing parent tramadol as well as tramadol metabolites produced in the animals. These compounds can then be absorbed by the plant roots and also leached into the local water supplies. The presence of tramadol in roots is, thus, due to an anthropogenic contamination with the synthetic compound.     

α-Mannosidases from the Digestive Fluid of <Emphasis Type="Italic">Rhynchophorus Palmarum</Emphasis> Larvae as Novel Biocatalysts for Transmannosylation Reactions

Two biological fluids, namely hemolymph and digestive fluid from the larval stage of Rhynchophorus palmarum Linneaus, a serious pest in agroecosystem exploiting oil palm, were screened for hydrolytic activities, by the use of synthetic and natural glycoside substrates. Several exo and endoglycosidase activities were observed but, the interesting α-mannosidase activity (0.41 ± 0.04 UI) had attracted our attention. So, we have previously demonstrated that this activity harbours four distinctive α-mannosidase isoforms named RpltM, RplM1, RplM2 and RplM3. We have extended this work to determine the ability of these enzymes to catalyze synthesis reactions. Finally, we have revealed that, α-mannosidases from the digestive fluid of R. palmarum larvae catalyze transmannosylation reactions. The stability of the enzymes and the optimization of the transfer product yield were studied as functions of pH, enzyme unit, starting concentration of donor or acceptor and time. It was shown that, in experimental optimum conditions, average yields of 12.34 ± 0.75, 12.15 ± 0.79, 5.59 ± 0.35 and 8.43 ± 0.50% were obtained for the α-mannosidases RpltM, RplM1, RplM2 and RplM3, respectively. On the basis of this work, α-mannosidases from the digestive fluid of Rhynchophorus palmarum larvae appear to be a valuable tool for the preparation of neoglycoconjugates.     

Villarinol, a new alkenoyloxyalkenol derivative from the endemic Philippine Rubiaceae species Villaria odorata

Villarinol (1), a new alkenoyloxy alkenol metabolite, has been isolated from the dichloromethane extract of Villaria odorata, an endemic Rubiaceae Philippine plant, along with the known compounds stigmasterol and 4-hydroxybenzaldehyde. The structure of 1 was elucidated on the basis of spectroscopic and spectrometric studies. The extracts of V. odorata exhibited moderate inhibition against Mycobacterium tuberculosis H37Rv, based on the colorimetric microplate alamar blue assay.     

Xanthones and Oxepino[2, 3‐b]chromones from Three Endophytic Fungi

Three new metabolites, microsphaeropsones A–C ( 1 – 3 ) with a unique oxepino[2,3‐b]chromen‐6‐one (ring‐enlarged xanthone) skeleton, were isolated from the endophytic fungus Microsphaeropsis species, co‐occurring with their putative biogenetic anthraquinoide precursors citreorosein ( 4 ) and emodin ( 5 ). From another Microsphaeropsis species, large amounts of fusidienol A ( 8 a ), smaller amounts of emodin ( 5 ), the known aromatic xanthones 9 a and 9 b , the new 3,4‐dihydrofusidienol A ( 8 b ), and the new aromatic xanthone 9 c were isolated. The endophyte Seimatosporium species produced a new aromatic xanthone, seimatoxanthone A ( 10 ), and 3,4‐dihydroglobosuxanthone A ( 12 ), closely related to α‐diversolonic ester ( 13 ) from Microdiplodia sp.. The structures were determined mainly by extensive 1D and 2D NMR experiments and supported by X‐ray single‐crystal analysis of 1 and the oxidation product 7 . The absolute configurations of the microsphaeropsones A–C ( 1 – 3 ) were established by comparison of the electronic and vibrational circular dichroism (ECD and VCD) spectra of 1 with time‐dependent DFT (TDDFT) and DFT calculations by using either the solid‐state structures or DFT‐optimized geometries as inputs. Preliminary studies indicated that 1 , 2 , and enone 7 showed antibacterial, fungicidal, and algicidal properties.