Fire Retardancy of Cementitious Panels with Larch and Spruce Bark as Bio-Admixtures.

The aim of this study is to investigate the production of fire-resistant panels made out of bark from spruce (Picea abies), larch (Larix decidua Mill.) and cement. This research included test panels produced from bark, cement, water and cement-bonded recycling material aiming for the target density of 750 kg/m3. The physical (density, dimension stability, thickness swelling) and mechanical properties such as tensile strength and compressive strength together with fire resistance were tested. Considering the results, appealing values have been achieved: max. compressive strength: 3.42 N/mm2; max. thickness swelling: 5.48%; and density: 515 to 791 kg/m3. In principle, the properties of the produced panels depend not only on the density, but also on the hydration and, above all, on the compaction and the composition of the boards. The fire tests demonstrated that the produced panels have an enormous potential in terms of fire resistance and could be utilized for fire-retardant applications.

Selected Properties of Cement Bound Spruce and Larch Bark Bio-Aggregates.

The aim of this study is to investigate the suitability of spruce and larch bark for the production of cement-bonded composites. At the beginning of this research, the curing behaviour of the admixtures was quantified with temperature profiles when testing spruce, larch, pine and poplar bark, to determine the compatibility between the components of the bio-aggregates, to analyse the cement curing and to establish which bark species should be successfully included in cement bonded composites. Considering the results, it was observed that the average densities of 600-700 kg/m3 of bio-aggregates are 40-55% lower than that of established products on the market, although spruce and larch bark are in a similar range. The situation is different for the compressive strength, as larch bark showed up to 30% higher values than spruce bark. This study revealed also different hardening characteristics of the two cement types used as binders for spruce and larch bark. The results of this study demonstrated that tree bark of Picea abies and Larix decidua Mill. can be successfully utilized for the production of a cement-bonded composite material.

In vitro inhibitory effects of plant-derived by-products against Cryptosporidium parvum.

Disposal of organic plant wastes and by-products from the food or pharmaceutical industries usually involves high costs. In the present study, 42 samples derived from such by-products were screened in vitro against Cryptosporidium parvum, a protozoan parasite that may contaminate drinking water and cause diarrhoea. The novel bioassay was previously established in the microtitre plate format. Human ileocaecal adenocarcinoma (HCT-8) cell cultures were seeded with C. parvum oocysts and parasite development was monitored by an indirect fluorescent antibody technique (IFAT) and microscopic assessment for clusters of secondary infection (CSI). Minimum inhibitory concentrations (MICs) and potential detrimental effects on the host cells were determined. An ethanolic extract from olive (Olea europaea) pomace, after oil pressing and phenol recovery, reproducibly inhibited C. parvum development (MIC = 250-500 µg mL(-1), IC50 = 361 (279-438) µg mL(-1), IC90 = 467 (398-615) µg mL(-1)). Accordingly, tyrosol, hydroxytyrosol, trans-coniferyl alcohol and oleuropein were selected as reference test compounds, but their contributions to the observed activity of the olive pomace extract were insignificant. The established test system proved to be a fast and efficient assay for identifying anti-cryptosporidial activities in biological waste material and comparison with selected reference compounds.

Quality assessment and antiplasmodial activity of West African Cochlospermum species.

The present study focuses on development of phytochemical methods for quality assessment of two West-African Cochlospermum species (Cochlospermum planchonii and Cochlospermum tinctorium) traditionally used for malaria treatment in Burkina Faso. Antimalarial activity of preparations from dried rhizomes (decoction) was tested against the chloroquine-sensitive Plasmodium strain 3D7 using the histidine-rich protein II (HRP2) drug susceptibility assay and compared with extract preparations using organic solvents of different polarity. Two main apocarotenoids were isolated from rhizomes of C. planchonii and unambiguously identified as dihydrocochloxanthine and cochloxanthine by spectroscopic methods. Comparative HPLC analyses of thirty-nine (39) samples from markets and from collections in natural habitats of both species showed a high variability in the accumulation of cochloxanthines and related carotenoids which were proven to be characteristic for rhizomes of both species and generally absent in leaves. Furthermore, content of total phenolics and antioxidant activities (DPPH and FRAP) as well as haemolytic activity of various extracts was tested. The HPLC method presented here was validated and provides a good separation of both compounds including 10 minor carotenoids. Extracts from both species and pure cochloxanthine offered pronounced antioxidant activities and weak haemolytic activity while, in contrast, dihydrocochloxanthine had a strong haemolytic effect at the highest concentration analysed. However, cochloxanthine as well as dihydrocochloxanthine showed erythroprotective effects against the haemolytic activity of the reference saponin. Moderate antiplasmodial activity between 16 and 63 µg/ml were observed with all tested extracts, and lower IC50 values were obtained with pure dihydrocochloxanthine (IC50=6.9 µg/ml), cochloxanthine (IC50=6.8 µg/ml), the DCM fraction (IC50=2.4 µg/ml) and the ethyl acetate fraction (IC50=11.5µg/ml) derived from a methanolic extract of C. planchonii. This study shows a major variability of carotenoid content and antiplasmodial activity of both C. planchonii and C. tinctorium. The high haemolytic activity of dihydrocochloxanthine (at 100 µg/ml) should be considered as a selection criterion for choosing species phenotypes for treatment.

Effects of cannabinoids Δ(9)-tetrahydrocannabinol, Δ(9)-tetrahydrocannabinolic acid and cannabidiol in MPP+ affected murine mesencephalic cultures.

Cannabinoids derived from Cannabis sativa demonstrate neuroprotective properties in various cellular and animal models. Mitochondrial impairment and consecutive oxidative stress appear to be major molecular mechanisms of neurodegeneration. Therefore we studied some major cannabinoids, i.e. delta-9-tetrahydrocannabinolic acid (THCA), delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in mice mesencephalic cultures for their protective capacities against 1-methyl-4-phenyl pyridinium (MPP(+)) toxicity. MPP(+) is an established model compound in the research of parkinsonism that acts as a complex I inhibitor of the mitochondrial respiratory chain, resulting in excessive radical formation and cell degeneration. MPP(+) (10 µM) was administered for 48 h at the 9th DIV with or without concomitant cannabinoid treatment at concentrations ranging from 0.01 to 10 µM. All cannabinoids exhibited in vitro antioxidative action ranging from 669 ± 11.1 (THC), 16 ± 3.2 (THCA) to 356 ± 29.5 (CBD) µg Trolox (a vitamin E derivative)/mg substance in the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) assay. Cannabinoids were without effect on the morphology of dopaminergic cells stained by tyrosine hydroxylase (TH) immunoreaction. THC caused a dose-dependent increase of cell count up to 17.3% at 10 µM, whereas CBD only had an effect at highest concentrations (decrease of cell count by 10.1-20% at concentrations of 0.01-10 µM). It influenced the viability of the TH immunoreactive neurons significantly, whereas THCA exerts no influence on dopaminergic cell count. Exposure of cultures to 10 µM of MPP(+) for 48 h significantly decreased the number of TH immunoreactive neurons by 44.7%, and shrunken cell bodies and reduced neurite lengths could be observed. Concomitant treatment of cultures with cannabinoids rescued dopaminergic cells. Compared to MPP(+) treated cultures, THC counteracted toxic effects in a dose-dependent manner. THCA and CBD treatment at a concentration of 10 µM lead to significantly increased cell counts to 123% and 117%, respectively. Even though no significant preservation or recovery of neurite outgrowth to control values could be observed, our data show that cannabinoids THC and THCA protect dopaminergic neurons against MPP(+) induced cell death.

Alcoholysis of naturally occurring imides: misleading interpretation of antifungal activities.

The frequent presence of the sulfur-containing amide penangin (10) in leaf extracts of Glycosmis species turned out to be the result of decomposition of imides generated by extraction and storage in MeOH. Reinvestigation of Glycosmis mauritiana and G. cf. puberula with acetone revealed the presence of six imides. In addition to penimides A (1) and B (2) and ritigalin (6), three new derivatives, krabin (4), isokrabin (5), and methoxypenimide B (3), were isolated and identified by spectroscopic methods. All six imides were shown to be susceptible to different rates of methanolic cleavage, leading to their corresponding methyl esters and sulfur-containing amides. Whereas the decomposition products penangin (10), isopenangin (11), and sinharin (14) are known, the corresponding cleavage of methyl N-methylthiocarbamate (7) from ritigalin (6), monitored in situ by (1)H NMR spectroscopy, is described here for the first time. Its structure was further confirmed by GC-MS coupling. HPLC-UV comparison of many different samples of G. mauritiana, extracted with MeOH, revealed considerable chemical variations in sulfur-containing amides, strongly correlated with different antifungal potency. The lack of activity of many methanolic crude extracts can be explained by a preponderance of the inactive decomposition product penangin (10), whereas the corresponding naturally occurring imides penimides A (1) and B (2) and methoxypenimide B (3), extracted with acetone, showed high fungitoxic properties.

Inhibition of leukotriene biosynthesis by stilbenoids from Stemona species.

Fifteen stilbenoids and two alkaloids from Stemona collinsae, S. tuberosa, and S. peirrei were tested alongside the commercially available stilbenoids resveratrol and pinosylvin for inhibition of leukotriene formation in an ex vivo test system based on activated human neutrophilic granulocytes. The stilbenoids resveratrol (1), pinosylvin (2), dihydropinosylvin (3), stilbostemin A (4), stilbostemin B (5), stilbostemin D (6), stilbostemin F (7), stilbostemin G (8), stemofuran B (9), stemofuran C (10), stemofuran D (11), stemofuran G (12), stemofuran J (13), stemanthrene A (14), stemanthrene B (15), stemanthrene C (16), and stemanthrene D (17) showed structure-dependent activities with IC(50) values ranging from 3.7 to >50 microM. The alkaloids tuberostemonine (18) and neotuberostemonine (19) were inactive at a concentration of 50 microM.

Antioxidant dehydrotocopherols as a new chemical character of Stemona species.

From the roots of various Stemona species four new dehydrotocopherols (chromenols) were isolated and their structures and stereochemistry elucidated by spectroscopic methods. The double bond between C-3 and C-4 proved to be a typical chemical character of the genus found in most of the species. Various C-methylations of the aromatic ring reflect differences in methyltransferase activities and agreed with the current species delimitations showing an exclusive accumulation of dehydro-delta-tocopherol for the Stemona tuberosa group, whereas different provenances of Stemona curtisii were characterized by dehydro-gamma-tocopherol accompanied by small amounts of dehydro-alpha-tocopherol. From Stemona collinsae all four tocopherols were isolated with a clear preponderance of dehydro-delta-tocopherol accompanied by smaller amounts of the rare dehydro-beta-tocopherol. Stemona burkillii and a group of unidentified species showed a weak accumulation trend towards dehydro-alpha-tocopherol, whereas Stemona cochinchinensis and especially Stemona kerrii clearly differed by a preponderance of chromanol derivatives. In Stemona cf. pierrei no tocopherols could be detected at all. Based on TLC tests and microplate assays with the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH*) the antioxidant capacities of all chromenol derivatives were comparable with that of alpha-tocopherol showing no significant differences among each other, except for a more rapid kinetic behaviour of the 5,7,8-methylated dehydro-alpha-tocopherol.

Dihydrophenanthrenes and other antifungal stilbenoids from Stemona cf. pierrei.

Three new dihydrophenanthrenes, stemanthrenes A-C, along with the new dihydrostilbene stilbostemin G were isolated and identified from the underground parts of Stemona cf. pierrei together with the known pinosylvin, 4'-methylpinosylvin, dihydropinosylvin, stilbostemins B, D, and E as well as the pyrrolo[1,2-a]azepine alkaloids protostemonine and stemonine. The structures of all new stilbenoids, elucidated by NMR analyses, showed a common substitution pattern for aromatic ring A and characteristic C-methylations for ring B. The trivial name racemosol, previously reported for S. collinsae, was renamed to stemanthrene D due to its priority for another compound. Bioautographic tests on TLC plates with Cladosporium herbarum displayed high antifungal activity for compounds with an unsubstituted aromatic ring A, e.g. pinosylvin, but only weak effects for the higher substituted stilbostemin G and stemanthrenes A-C. Similar results were obtained by germ tube inhibition of five microfungi using 2-fold serial broth dilutions determined by a microplate reader. Because of weak inhibition and chemical instability of stemanthrenes, no EC(50) and EC(90) values could be calculated.

Two pyrrolo[1,2-a]azepine type alkaloids from Stemona collinsae Craib: structure elucidations, relationship to asparagamine A, and a new biogenetic concept of their formation.

The alkaloids 1',2'-didehydrostemofoline (2) and 2'-hydroxystemofoline (3) from Stemona collinsae Craib (Stemonaceae) were studied by X-ray crystallography and NMR spectroscopy, and they are compared with the parent compound stemofoline (1). The X-ray analysis of the CH2Cl2 solvate of 2'-hydroxystemofoline (3) allowed the determination of the absolute configuration of this compound unequivocally, whereas optical rotation was used to infer the absolute configuration of 1',2'-didehydrostemofoline (2). Based on these results, it is shown that asparagamine A isolated from Asparagus racemosus Willd. (Asparagaceae) is identical to 1',2'-didehydrostemofoline obtained from S. collinsae Craib, and that the reported plant source of asparagamine A was most likely a Stemona species. In the context of the current investigations, a novel concept on the biosynthesis of Stemona alkaloids has been worked out and is presented here.

Feeding deterrence and contact toxicity of Stemona alkaloids-a source of potent natural insecticides.

On the basis of chronic feeding bioassays with neonate larvae of Spodoptera littoralis reared on an artificial diet, the methanolic leaf and root extracts from Stemona collinsae displayed very high insect toxicity compared to those of two Aglaia species, a commercial Pyrethrum extract, and azadirachtin, whereas S. tuberosa extracts demonstrated low activity in roots and no activity in leaves. Beyond that, in leaf disk choice tests against fifth instar larvae, S. collinsae showed strong antifeedant activity, whereas S. tuberosa was characterized by remarkable repellency. The anti-insect properties of both species were based on pyrrolo[1,2-a]azepine alkaloids, from which didehydrostemofoline (asparagamine A) was the major compound of the roots of S. collinsae, exhibiting the highest toxicity in feeding assays. Saturation and hydroxylation of the side chain in the co-occurring stemofoline and 2'-hydroxystemofoline, respectively, led to an increasing loss of activity. Contact toxicity tests with stemofoline and didehydrostemofoline exhibited even higher activities than those of Pyrethrum extract. Tuberostemonine was the dominating alkaloid in the roots of S. tuberosa, showing outstanding repellency but no toxic effects.