Organic chemistry of Protosalvinia (Foerstia) from the Chattanooga and New Albany Shales

Vertical samplings of Protosalvinia, a thalloid Upper Devonian alga from the Chattanooga and New Albany Shales, are chemically analyzed and correlated with the organic chemical constituents isolated from associated shale matrices. Normal, saturated acids (n-C₈ to n-C₃₆n-paraffins (C₁₀ to C₃₆), showing an odd carbon-number preference, branched-chain alkanes, and vanadyl porphyrins isolated from Protosalvinia vary in their concentrations with depth of burial and with the dominant associated morphology of Protosalvinia, i.e., P. arnoldii, P. ravenna, P. furcata. Organic constituents of shales, in general, reflect those detected in thalli; relative concentrations, molecular diversity, carbon chain-lengths and maxima of compounds extracted from both shale and fossil material are similar. Pristane, phytane and porphyrins are probably derived from a chlorophyllous organism, while δ¹³C data corroborate a photosynthetic system operating in the primary biosynthesis of shale geochemistry. Crude-oil extracts of Protosalvinia-rich strata contain higher alkane and lower aromatic hydrocarbon concentrations than those of an average crude oil. Chemical variations among forms of Protosalvinia suggest biochemical differences in original plant composition rather than diagenetic transitions; field observations of morphological trends seen in vertical samplings may be used in crude extrapolations of the organic chemical compositions of shale strata.     

Microbial Oxidation of Isoprenoid Alkanes,Phytane, Norpristane and Farnesane

Rhodococcus sp. BPM 1613, a pristane oxidizing microorganism, grows on isoprenoid hydrocarbons such as phytane (2,6,10,14-tetramethylhexadecane), norpristane (2,6,10-trimethylpentadecane) and farnesane (2,6,10-trimethyldodecane) as the sole carbon source, resulting in accumulation of oxidation products in the culture broth. The oxidation products of phytane, norpristane and farnesane in the respective culture broth were isolated and purified by the use of silica gel column chromatography. Their chemical structures were determined by instrumental analyses such as IR, NMR and mass spectrometry. The oxidation products of phytane were identified as 2,6,10,14-tetramethyl-1-hexadecanol and 2,6,10,14-tetramethylhexadecanoic acid, the product of norpristane as 2,6,10-trimethyl-1-pentadecanol, and that of farnesane as 2,6,10-trimethyl-1-dodecanol. All these oxidation products were either monoalcohols or monocarboxylic acids derived through oxidation of the isopropyl terminus of each alkane.

In addition, the relationship between the terminal structure of isoprenoid hydrocarbons and microbial oxidation was explored on the basis of these results.     

Fungal Metabolite from Members of the Genus Rhizopus

A fluorescent metabolite present in seven members of the genus Rhizopus was isolated. This compound appeared green before spray treatment and purple after spray treatment with p-anisaldehyde in visible light. Subsequent purification and structural elucidation of the isolated compound yielded 1-[2,6,10,14-tetramethyl-17-carbomethyl heptadecyl]-1-[2,6,10,14-tetramethyl-17-methanoyl heptadecyl]-benzene.     

Anaerobic Microbial Growth from Components of Cretaceous Shales

Cretaceous rock formations have been shown to harbor extant sulfate-reducing microbial communities. At these sites, microbial activity is concentrated at rock interfaces where there is likely a diffusion of nutrients from low permeability organic rich shales to higher permeability sandstones. This study was undertaken to further characterize this process and to determine the components of shale that provide electron donors for sulfate reduction activity. To this end, samples of Cretaceous sandstones were incubated with ground shales from available depths at the Cerro Negro exploratory drilling site in northwestern New Mexico. Both sulfate consumption as an indicator of sulfate reduction and acetate production were stimulated in the sandstone-shale incubations. The greatest levels of stimulation were observed with shales originally closest to the lower sandstone-shale interface and a strong correlation was observed between shale organic carbon and microbial activity. These results suggested that the organic matter in shale was supplying the needed electron donor for the sulfate-reducing microbial community. Further evidence for this interpretation was provided when a pure culture of Acetobacterium psammolithicum , an acetogen isolated from this site, was stimulated to produce acetate by the addition of autoclaved shales. To investigate the components in shale that were responsible for stimulating microbial activity, we extracted shale organic material. Aqueous extracts and to a lesser extent neutral ether extractions stimulated activity although neither to the same extent as the shale itself. Alkaline aqueous extracts were fractionated using XAD-7 resin. Each of the fractions contributed to some degree, but the greatest stimulation in microbial activity was attributed to both the hydrophilic eluate and to the fulvic acid fraction. These data indicate that a relatively complex group of organic compounds supply electron donors to the sandstone microbial communities.     

Carbon isotopic abundances in Mesozoic and Cenozoic fossil plants: Palaeoecological implications

Carbon isotopic abundances have been measured for more than one hundred samples of fossil plants ranging in age from middle Triassic to late Tertiary. Most of the plant fossils were identified at the specific or generic level and were selected as representing a variety of continental environments, including xeric and humid habitats. Material analysed included numerous fragments of flowers, seeds, fruits, leaves and wood, as well as a single amorphous lignite sample. The analyses performed for the plant fragments indicate relatively constant isotopic compositions during this time interval, with plant δ¹³C values ranging between -28 and -20%. These values are within the range for living terrestrial plants with C₃, photosynthesis, although values more positive than -23% are rare in C₃ plants and typically found in plants growing under environmental stress. Lower δ¹³C values might have been expected owing to the much higher CO₂, levels of the Cretaceous atmosphere that have been inferred from marine carbonates. No fossils with values indicating C₄, photosynthesis were discovered. Fossil plants from inferred mesic environments showed δ¹³C values ranging between -26.7 and -24.1%. Highest δ¹³C values in angiosperms (up to -20.1%) were measured for Late Cretaceous combretaceous flowers from Portugal. Some cheirolepidiaceous conifers from the Early Cretaceous also showed high δ¹³C values. Values measured for Pseudofrenelopsis varians and Glenrosa taxensis were -21.9%, and values of gymnosperm wood, probably of cheirolepidiaceous affinity, were -19.0%. These high values are in accordance with inferred ecological conditions for the fossil plants. They may suggest a tendency for C₄,-like photosynthesis, although the data are equivocal. Higher values (-17.3%) clearly falling outside the C₃, range were, however, obtained from a single lignite fragment of Late Cretaceous (Maastrichtian) age. The nature of this plant fragment is unknown, but the result suggests that C₄-like photosynthesis was present at least in some latest Cretaceous vegetation. A hadrosaurian dinosaur with well-preserved collagen-like organic matter from the same deposit showed δ¹³C values around-16%, which also suggests the presence of CAM or even C₄ plants in the latest Cretaceous. □Carbon isotopic abundances, δ¹³C values, dinosaurs, plants, photosynthetic pathways, Mesozoic.     

Primary and diagenetic microstructures in trilobites

McAllister, John E. & Brand, Uwe 1989 01 15: Primary and diagenetic microstructures in trilobites. Lethaia , Vol. 22, pp. 101–111. Oslo. ISSN 0024–1164.
Ordovician and Devonian trilobites were studied by scanning electron microscopy (SEM) to define primary and diagenetic microstructures. Primary structures such as Osmólska cavities and hexagonal surface openings are present in samples obtained from both shale and limestone lenses in shales. Generally, samples with primary microstructures are also geochemically well preserved. Diagenetic microstructures were found in samples from shales and limestones, but those from limestones are the most geochemically and microstructurally altered. 'Dendritic' patterns and fused matrices were found in the altered cuticles of trilobites of different species and ages and are therefore considered a normal feature of the diagenetic alteration of cuticular calcite. Primary and diagenetic microstructures of trilobite cuticles are independent of size, species and age of the specimens, but are largely controlled by lithology and thus diagenesis. * Trilobita, primary-, diagenetic microstructures, fossil diagenesis .     

Environmental hazards of arsenic associated with black shales: a review on geochemistry, enrichment and leaching mechanism

Black shales are high organic matter-rich dark coloured mudstones those are often deposited during ??oceanic anoxia events??. Most of the black shale horizons are rich in arsenic far above their average crustal abundance and are susceptible to weathering eventually leaching high As contents to the surrounding environment causing As enrichment in soil and water which adversely affect the living beings. Numerous arsenic contaminations are being reported from black shale hosted areas globally, hence, making extremely crucial to understand the processes of enrichment, leaching and broader prospective of environmental hazards. Few studies have shown arsenic concentrations as high as 6,000?mg/kg within black shales causing groundwater enrichment up to hundreds mg/L. Arsenic is commonly attached to sulphide mineral structure and partly to organic matter and clay contents during deposition and diagenetic processes. Majority of sulphide bound arsenic becomes available to oxidative dissolution processes in presence of atmospheric oxygen and water which is further triggered by certain microbial community such as Acidophilus ferrooxidans hence, enhancing arsenic release. Physical weathering processes carry the arsenic-rich shale constituents to the depositional site where it is dissolved subsequently. Chemical diffusion and mechanical transport are two prime processes transporting arsenic from black shale horizons to the water bodies or soil columns, while air pollutions are caused by combustions of organic matter-rich coaly shales.     

Degradation of the multiple branched alkane 2,6,10,14-tetramethyl-pentadecane (pristane) in Rhodococcus ruber and Mycobacterium neoaurum

Pristane, a highly branched hydrocarbon that also contains iso-branched termini, was used as a substrate for several alkane-metabolizing bacteria. Rhodococcus ruber and Mycobacterium neoaurum were able to utilize pristane for growth effectively. The intermediates produced by these bacteria during incubation with pristane were analyzed by gas chromatography (GC) and gas chromatography/mass spectra (GC/MS). The products revealed as products of 4-methyl pentanoic acid; methyl butanedioic acid; 2-methyl pentadioic acid; methyl propanedioic acid; 4-methyl heptanedioic acid; and 2,6,10,14-tetramethyl-pentadecan-3-one were detected in M. neoaurum cultures. In R. ruber, methyl butanedioic acid; 2-methyl pentadioic acid; 4,8-dimethylnonanoic acid, 4-methyl heptanedioic acid; 2,6,10-trimethylundecanoic acid; 3,7-dimethyl decanedioic acid; and 2,6,10,14-tetramethyl-pentadecan-3-one were detected. The occurrence of these intermediates showed that pristane could be catabolized not only via mono- but also by a di-terminal oxidation pathway. Furthermore, the presence of 2,6,10,14-tetramethyl-pentadecan-3-one; 3,7-dimethyldecandioate; and 2-methylbutandioate established a third pathway initiated by sub-terminal oxidation at the third carbon atom of pristane. Novel intermediates detected suggest simultaneous sub-terminal and di-terminal oxidation pathways.     

A comparison of triglycerides from aphids and their cornicle secretions

Direct mass spectrometry of extracts showed that body triglycerides from 30 species of aphids contained the same fatty acid radicals, C₆ (hexanoyl), C_6:2 (sorboyl), C₁₄ (myristoyl), and C₁₆ (palmitoyl) as did the cornicle secretions, but in many species the proportions of hexanoyl and/or palmitoyl triglycerides were greater in the body. When cornicle secretions were collected progressively so as to draw increasingly upon body fat reserves, their composition changed gradually towards that of the body extracts.All summer forms of Myzus persicae had similar body triglycerides, even when selected for resistance to organophosphorus insecticides, or bred for 3 months on an artificial diet. The composition of body triglycerides was also independent of colour in two aphid species in which pink and green forms were compared.Body extracts contain enough triglycerides for their composition to be determined in single aphids and the use of body extracts allows examination of aphids lacking cornicles and of specimens that do not give cornicle secretion because of low body turgor. Although, as in the case of cornicle secretions, the triglyceride composition of body extracts was not well correlated with taxonomic position, body extracts provide a second chemical characteristic that can be used to define a particular species.     

Microbody enzymes and carboxylases in sequential extracts from c(4) and c(3) leaves

A seven-step sequential grinding procedure was applied to leaves of Atriplex rosea, Sorghum sudanense, and Spinacia oleracea to study the distribution of carboxylases and microbody enzymes. In the extracts from C₄ species there were 7- to 10-fold reciprocal changes in specific activities of ribulose-1, 5-diphosphate carboxylase and phosphoenolpyruvate carboxylase. No such changes occurred in sequential extracts from spinach. No inhibitors of ribulose-1, 5-diphosphate carboxylase were detected when the mesophyll extracts of Sorghum were assayed together with spinach extracts. These results reaffirm the conclusion of others that phosphoenolpyruvate carboxylase is largely confined to the mesophyll in these species and ribulose-1, 5-diphosphate carboxylase to the bundle sheath. The specific activities of glycolate oxidase and hydroxypyruvate reductase in bundle sheath extracts were two to three times those in mesophyll fractions. Catalase behaved similarly in Atriplex rosea but in Sorghum the specific activity was virtually the same in all fractions. From the relative amounts of these enzymes present, and comparison with the data obtained from spinach, it is concluded that typical leaf peroxisomes are present in the bundle sheaths of both C₄ species and in the mesophyll of Atriplex rosea. The relative enzyme activities in the mesophyll of Sorghum suggest that the microbodies there are of the non-specialized type found in many nongreen tissues. The activities of the microbody enzymes in the bundle sheath of Sorghum seem quite inadequate to support photorespiration.     

Lipid composition of halophilic species of Dunaliella from the dead sea

The lipid patterns of six halophilic Dunaliella species from the Dead Sea (C₉, D_11a, D_11b, D₁₃, F_20a and D. viridis) were found to be generally similar to those of halotolerant Dunaliella species previously examined, except for the presence in the halphilic Dunaliella of small to trace amounts of one or more (up to five) unidentified glycolipids. The lipids of two of the halophilic algae, species C₉ and D_11b, were studied in detail and were found to be similar in composition. Glycolipids were the major group (55.0 and 53.2 mol % for C₉ and D_11b, respectively), followed by neutral lipids (mainly triacyglycerols: 21.3 mol %; 24.6 mol %), whereas phospholipids were a much smaller fraction (6.5 mol %; 5.8 mol %). Monogalactosyldiacylglycerol was the largest component (22.0 mol %; 24.3 mol %) but digalactosyldiacylglycerol (18.7 mol %; 14.9 mol %) and sulfoquinovosyldiacylglycerol (14.3 mol %; 14.0 mol %) were also present in high concentrations. All phospholipids were present at low concentrations: phosphatidylglycerol (4.4 mol %; 3.1 mol %); phosphatidylethanolamine (1.1 mol %; 0.7 mol %); phosphatidylcholine (0.9 mol %; 1.9 mol %); and phosphatidylinositol (traces). Diacylglyceryl-O-(N,N,N-trimethyl)homoserine was present in C₉ and D_11b (3.3 mol %; 9.3 mol %) and in all the other species examined. Fatty acid composition of the individual lipid components of C₉ and D_11b showed characteristic differences between glycolipids and phospholipids, in a similar pattern for both algae. The major fatty acids detected in all species examined were -linolenic, linoleic, palmitic, oleic and a polyunsaturated sixteen carbon acid.     

Steroids,phthalyl esters and hydrocarbons from Balanites wilsoniana stem bark

IR assay for sapogenin of Balanites wilsoniana revealed 0.2% in the root wood, 0.7% in the root bark, 0.3% in the stem bark, 1.4% in the fatty seed and 0.6%. w/w in the leaf. The 25 α-epimers predominated in all parts except in the root wood. Six glucosideshaving diosgenin or yamogenin as aglycones were found and one was characterized diosgenin 3 β-d-glucopyranoside from IR, MS and NMR studies. Cholesterol, stigmasterol, sitosterol, 25 α-spirosta-3:5-diene and 25-β-spirosta-3:5-diene were also present. Free diosgenin and dienes were detected in appreciable quantities in the fat from the bark. The ‘unsaponifiable’ fraction of this fat contained phthalyl esters (mainly dioctyl and dibutyl) and saturated hydrocarbons C₁₀C₃₂ (with C₁₀C₂₀ predominating), together with the above mentioned steroids.     

7‐methylheptacosane is a major component of the contact sex pheromone of the cerambycid beetle Neoclytus acuminatus acuminatus

Abstract Male Neoclytus acuminatus acuminatus (F.) (Coleoptera: Cerambycidae) attempt to mate with females only after touching them with their antennae, suggesting that mate recognition is mediated by contact pheromones in the cuticular wax layer of females. Consistent with that hypothesis, males exhibit similar responses to dead females in laboratory bioassays, but not to solvent‐washed dead females with their cuticular hydrocarbons removed. The mating response of males is restored when solvent extracts are reapplied to carcasses of solvent‐washed females, indicating that the contact pheromone is present in solvent extracts. Solvent extracts of the female cuticle contain six methylalkanes that are not present in extracts of males, three of which (7Me‐C₂₅, 7Me‐C₂₇ and 9Me‐C₂₇) constitute almost 40% of the total hydrocarbons. The bioactivity of these three compounds is tested by applying synthetic standards to solvent‐washed carcasses of females and presenting them to males. Standards are tested singly, pairwise and as the complete blend; freeze‐killed females serve as controls. Males attempt to couple with solvent‐washed female carcasses treated with 7Me‐C₂₇ alone and in combination with 9Me‐C₂₇ but only the complete blend elicits the same number of mounting and coupling attempts as does the control. These findings suggest that 7Me‐C₂₇ (7‐methylheptacosane) is the major component of the contact sex pheromone of N. a. acuminatus and that 7Me‐C₂₅ and 9Me‐C₂₇ act as synergists.     

Immunoaffinity techniques applied to the purification of gibberellins from plant extracts

The use of immunoaffinity columns containing anti-gibberellin (GA) antibodies for the selective purification of GAs in plant extracts is described. GA₁, GA₃, GA₄, GA₅, GA₇, and GA₉ conjugates to bovine serum albumin were synthesized and used to elicit anti-GA polyclonal antibodies (Abs) in rabbits. Protein A purified rabbit serum, containing a mixture of anti-GA Abs, was immobilized on matrices of Affi-gel 10 or Fast-Flow Sepharose 4B. Columns of these immunosorbents retained a wide range of C-19 GA methyl esters, but no C-20 GA methyl esters. Quantitative recovery of C-19 GA methyl esters was achieved from the columns, which, after reequilibration in buffer, could be reused up to 500 times. The immunosorbents were tested by examination of extracts from immature soybean and pea seeds. GAs were initially purified by passing the extracts through DEAE-cellulose and concentrating them on octadecylsilica. The extracts were methylated and further purified on the mixed anti-GA immunoaffinity columns. GAs were detected and quantified as methyl esters or methyl ester trimethylsilyl ethers by gas chromatography-mass spectrometry-selected ion monitoring. GA₇ was found in soybean seeds, 17 days after anthesis, at low levels (8.8 nanograms per gram fresh weight). C-19 GAs were examined in cotyledons, embryonic axes, and testae of G2 pea seeds harvested 20 days after anthesis. High levels of GA₂₀ and GA₂₉ were found in cotyledons (3580 and 310 nanograms per gram fresh weight, respectively) and embryonic axes (5375 and 1430 nanograms per gram) fresh weight, respectively). Lower levels of GA₉ were found in cotyledons and embryonic axes (147 and 161 nanograms per gram fresh weight, respectively). GA₉ was the major GA of testae at levels of 195 nanograms per gram fresh weight. Trace quantities of GA₂₀ and GA₅₁ were also observed in testae.     

Biomarker indications for microbial contribution to Recent and Late Jurassic carbonate deposits

Summary Biomarker investigations were applied to the hydrocarbon fractions of three Recent (cyanobacterial mat, Lake Van microbialite and Lake Satonda microbialite) and two Late Jurassic carbonate samples obtained from sponge bioherms. The relative concentrations ofn-alkanes, monomethyl alkanes, acyclic isoprenoids, steroids and hopanoids in these samples are studied and their probable biological precursors are discussed. Normal alkanes with carbon chain lengths ranging from C₁₅ to C₃₄ and monomethyl alkanes ranging from C₁₇ to C₂₁ with a varying methyl branching pattern are found. The major hydrocarbons are low molecular weight (LMW)n-alkanes (C₁₅–C₂₁) with a slight to strong predominance ofn-heptadecane (C₁₇). High molecular weight (HMW)n-alkanes occur in low to moderate relative concentrations showing a preference of odd-carbon numbered compounds with a maximum at C₂₉. Within the acyclic isoprenoids, pristane, phytane/phytene, pentamethyl-eicosane, squalane and lycopane could be identified. Polycyclic terpenoids of the sterane and/or hopane type are present in all carbonate samples. The carbon numbers of these components range from 27 to 29 and 27 to 32, respectively. These organic compounds identified can be attributed to various source organisms such as cyanobacteria, archaebacteria, algae and vascular plants. All hydrocarbon fractions of the samples are characterized by moderate to high relative concentrations of compounds derived from cyanobacteria, signifying the role of these organisms as contributors to the Recent as well as to the Late Jurassic carbonate deposits.     

A stable and productive marine microbial community was sustained through the end‐Devonian Hangenberg Crisis within the Cleveland Shale of the Appalachian Basin,United States

The end‐Devonian Hangenberg Crisis constituted one of the greatest ecological and environmental perturbations of the Paleozoic Era. To date, however, it has been difficult to precisely constrain the occurrence of the Hangenberg Crisis in the Appalachian Basin of the United States and thus to directly assess the effects of this crisis on marine microbial communities and paleoenvironmental conditions. Here, we integrate organic and inorganic chemostratigraphic records compiled from two discrete outcrop locations to characterize the onset and paleoenvironmental transitions associated with the Hangenberg Crisis within the Cleveland Shale member of the Ohio Shale. The upper Cleveland Shale records both positive carbon (δ¹³C_org) and nitrogen (δ¹⁵N_total) isotopic excursions, and replenished trace metal inventories with links to eustatic rise. These dual but apparently temporally offset isotope excursions may be useful for stratigraphic correlation with other productive end‐Devonian epeiric marine locations. Deposition of the black shale succession occurred locally beneath a redox‐stratified water column with euxinic zones, with signs of strengthening denitrification during the Hangenberg Crisis interval, but with an otherwise stable and algal‐rich marine microbial community structure sustained in the surface mixed layer as ascertained by lipid biomarker assemblages. Discernible trace fossil signals in some horizons suggest, however, that bioturbation and seafloor oxygenation occurred episodically throughout this succession and highlight that geochemical proxies often fail to capture these rapid and sporadic redox fluctuations in ancient black shales. The paleoenvironmental conditions, source biota, and accumulations of black shale are consistent with expressions of the Hangenberg Crisis globally, suggesting this event is likely captured within the uppermost strata of the Cleveland Shale in North America.     

Kytococcus aerolatus sp. nov., isolated from indoor air in a room colonized with moulds

A Gram-positive, coccoid bacterial isolate (02-St-019/1^T), forming beige pigmented colonies was obtained from an indoor air sample. Based on 16S rRNA gene sequence similarity studies it was determined that this isolate 02-St-019/1^T belonged to the genus Kytococcus, showing sequence similarties of 98.6% to Kytococcus schroeteri DSM 13884^T and 98.3% to Kytococcus sedentarius DSM 20547^T, respectively. The diagnostic diaminoacid of the peptidoglycan was lysine, cell wall sugars were ribose and xylose. The major menaquinones detected were MK-7 and MK-8. The polar lipid profile consisted of the major phospholipids diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylserine and phosphatidylinositol mannoside. Fatty acid patterns were composed of major amounts of the iso- and anteiso-branched fatty acids anteiso C_17:0, iso C_15:0 and iso C_17:0 and unsaturated fatty acids (C_17:1 ω8c, iso C_17:1 ω9c, and C_17:1 ω8c) with smaller amounts of the straight-chain fatty acids C_15:0, C_16:0 and C_17:0. The results of DNA–DNA hybridizations and physiological and biochemical tests clearly allowed a genotypic and phenotypic differentiation of strain 02-St-019/1^T from the two described Kytococcus species. On the basis of these results a novel species to be named Kytococcus aerolatus sp. nov., is proposed, with the type strain 02-St-019/1^T (=DSM 22179^T=CCM 7639^T).     

C(4) Photosynthesis: Light-dependent CO(2) Fixation by Mesophyll Cells, Protoplasts, and Protoplast Extracts of Digitaria sanguinalis

Mesophyll cells, protoplasts, and protoplast extracts of Digitaria sanguinalis were used for comparative studies of light-dependent CO₂ fixation. CO₂ fixation was low without the addition of organic substrates. Pyruvate, oxaloacetate, and 3-phosphoglycerate induced relatively low rates (10 to 90 μmoles/mg chlorophyll·hr) of CO₂ fixation when added separately. However, a highly synergistic relationship was found between pyruvate + oxaloacetate and pyruvate + 3-phosphoglycerate for inducing light-dependent CO₂ fixation in the mesophyll preparations. Highest rates of CO₂ fixation were obtained with protoplast extracts. Pyruvate, in combination with oxaloacetate or 3-phosphoglycerate induced light-dependent rates from 150 to 380 μmoles of CO₂ fixed/mg chlorophyll·hr which are equivalent to or exceed reported rates of whole leaf photosynthesis in C₄ species. Concentrations of various substrates required to give half-maximum velocities of CO₂ fixation were determined, with the protoplast extracts generally saturating at the lowest substrate concentrations. Chloroplasts separated from protoplast extracts showed little capacity for CO₂ fixation. The results suggest that CO₂ fixation in C₄ mesophyll cells is dependent on chloroplasts and extrachloroplastic phosphoenolpyruvate carboxylase.     

Proanthocyanidins in Pruning Wood Extracts of Four European Plum (Prunus domestica L.) Cultivars and Their hLDHA Inhibitory Activity

European plum tree (Prunus domestica L.) is cultivated in many countries for its delicious and nutritive fruit and, accordingly, certain amounts of wood (from pruning works) are generated every year. The main objective of this work was to value this agricultural woody residue, for which the chemical composition of pruning wood extracts from four European plum cultivars was investigated, and the human lactate dehydrogenase A (hLDHA) inhibitory activity of plum wood extracts and pure proanthocyanidins present in those extracts was measured. For the chemical characterization, total phenolic content and DPPH radical-scavenging assays and HPLC-DAD/ESI-MS analyses were performed, the procyanidin (−)-ent-epicatechin-(2α→O→7,4α→8)-catechin ( 4 ), the phenolic glucoside (−)-annphenone ( 3 ) and the flavan-3-ol catechin ( 1 ) being the major components of the wood extracts. Some quantitative and qualitative differences were found among plum cultivars, and the content of proanthocyanidins ranged from 1.51 (cv. ‘Claudia de Tolosa’) to 8.51 (cv. ‘De la Rosa’) mg g⁻¹ of dry wood. For the hLDHA inhibitory activity, six wood extracts and six proanthocyanidins were evaluated by a UV spectrophotometric assay, compound 4 showing the highest inhibitory activity (IC₅₀ 3.2 μM) of this enzyme involved on the excessive production of oxalate in the liver of patients affected by the rare disease Primary Hyperoxaluria.     

Antiparasitic activity of prenylated benzoic acid derivatives from Piper species

Fractionation of dichloromethane extracts from the leaves of Piper heterophyllum and P. aduncum afforded three prenylated hydroxybenzoic acids, 3-[(2E,6E,10E)-11-carboxy-3,7,15-trimethyl-2,6,10,14-hexadecatetraenyl)-4,5-dihydroxybenzoic acid, 3-[(2E,6E,10E)-11-carboxy-13-hydroxy-3,7,15-trimethyl-2,6,10,14-hexadecatetraenyl]-4,5-dihydroxybenzoic acid and 3-[(2E,6E,10E)-11-carboxy-14-hydroxy-3,7,15-trimethyl-2,6,10,15-hexadecatetraenyl]-4,5-dihydroxybenzoic acid, along with the known compounds, 4,5-dihydroxy-3-(E,E,E-11-formyl-3,7,15-trimethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid (arieianal), 3,4-dihydroxy-5-(E,E,E-3,7,11,15-tetramethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid, 4-hydroxy-3-(E,E,E-3,7,11,15-tetramethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid, 3-(3,7-dimethyl-2,6-octadienyl)-4-methoxy-benzoic acid, 4-hydroxy-3-(3,7-dimethyl-2,6-octadienyl)benzoic acid and 4-hydroxy-3-(3-methyl-1-oxo-2-butenyl)-5-(3-methyl-2-butenyl)benzoic acid. Their structures were elucidated on the basis of spectroscopic data, including homo- and heteronuclear correlation NMR experiments (COSY, HSQC and HMBC) and comparison with data reported in the literature. Riguera ester reactions and optical rotation measurements established the compounds as racemates. The antiparasitic activity of the compounds were tested against three strains of Leishmania spp., Trypanosoma cruzi and Plasmodium falciparum. The results showed that 3-(3,7-dimethyl-2,6-octadienyl)-4-methoxy-benzoic acid exhibited potent and selective activity against L. braziliensis (IC₅₀ 6.5 μg/ml), higher that pentamidine used as control. Moreover, 3-[(2E,6E,10E)-11-carboxy-3,7,15-trimethyl- 2,6,10,14-hexadecatetraenyl)-4,5-dihydroxybenzoic acid and 4-hydroxy-3-(3-methyl-1-oxo-2-butenyl)-5-(3-methyl-2-butenyl)benzoic acid showed moderate antiplasmodial (IC₅₀ 3.2 μg/ml) and trypanocidal (16.5 μg/ml) activities, respectively.