Structure-Elucidating Total Synthesis of the (Polyenoyl)tetramic Acid Militarinone C§

The (polyenoyl)tetramic acid militarinone C (1) heads a family of seven members. Before our work, the configuration of C-5 was unknown whereas the configurations of C-8' and C-10' were either (R,R) or (S,S). We synthesized the four stereoisomers of constitution 1, which conform with these insights. This included cross-coupling both enantiomers of the western building block (8) with both enantiomers of the eastern building block (9). The specific rotations of the resulting 1 isomers suggested that natural 1 is configured like the coupling partners (S)-8 and (R,R)-9. This conclusion was corroborated by degrading natural 1 to alcohol 35 and by proving its configurational identity with synthetic (R,R)-35.

A multicomponent herbal feed additive improves somatic cell counts in dairy cows - a two stage, multicentre, placebo-controlled long-term on-farm trial

In contrast to natural and historical diets of wild and domesticated ruminants, the diversity of plant species is limited in diets of modern dairy cows. Are "production diseases" linked to this? We conducted a trial to test the effects of a multicomponent herbal feed additive (HFA) on health, performance and fertility traits. A dose-finding study (DF) with 62 cows on 11 commercial farms compared a low (50 g) and a high (100 g) dose of HFA (HFA-50, HFA-100) with a placebo (PL). In a subsequent field trial (FT) with 280 cows on 30 commercial farms, HFA-100 was compared to PL. Cows were randomly assigned to HFA and PL groups and received HFA or PL individually daily from 14 days pre- to 300 days post-calving. Data were analysed with mixed effects models. No differences between HFA and PL were found regarding performance, body condition score and overall culling rates. A tendency towards lower milk urea for HFA-100 compared to PL (p = .06) was found in DF. HFA significantly reduced elevated milk acetone observations (≥10 mg/L) in the first 10 lactation weeks (HFA-100: 4%; HFA-50: 4%; PL: 12%) in DF. HFA-50 significantly reduced lameness incidence (HFA-100: 11%; HFA-50: 2%; PL: 14%) in DF. Calving intervals were 15 days shorter in HFA compared to PL in both trials, which could be confirmed by tendency (p = .07) in FT. In both trials, the proportion of test days with elevated somatic cell score (≥3.0) was significantly lower in HFA compared to PL (DF: HFA-100: 40%, HFA-50: 45% and PL: 55%; FT: HFA-100: 38% and PL: 55%) which is also reflected by tendency (p = .08) in lower culling rates due to udder diseases in FT. HFA showed no negative impact on any of the measured parameters. The effects of HFA indicate a potential of phytochemically rich and diverse feed additives for dairy cows' nutrition and physiology.

A Bufadienolide-Enriched Fraction of Bryophyllum pinnatum Inhibits Human Myometrial Contractility In Vitro

Bryophyllum pinnatum has been used since the 1970s to prevent premature labour, first in anthroposophic hospitals and, more recently, also in the main Swiss perinatal centres. However, it is not known which compounds in B. pinnatum leaves contribute to the tocolytic effect. Here we studied the effects of a flavonoid-enriched fraction, the corresponding flavonoid aglycon mixture, a bufadienolide-enriched fraction, and B. pinnatum leaf press juice on human myometrial contractility in vitro. The strength (area under the curve and amplitude) and frequency of contractions were recorded using strips of human myometrium mounted in an organ bath system. Cell viability assays were performed with the human myometrium hTERT-C3 and PHM1 - 41 cell lines. Repeated addition of the flavonoid-enriched fraction, flavonoid aglycon mixture, bufadienolide-enriched fraction, or B. pinnatum leaf press juice led to a progressive decrease of contraction strength, without jeopardising the vitality of myometrium strips. The bufadienolide-enriched fraction was the most active, since 1 µg/mL of the bufadienolide-enriched fraction lowered the area under the curve to 40.1 ± 11.8% of the initial value, whereas 150 µg/mL of the flavonoid-enriched fraction, 6.2 µg/mL of the flavonoid aglycon mixture, and 10 µg/mL of the B. pinnatum leaf press juice were required to achieve comparable inhibition. A progressive increase of contraction frequency was observed, except in the case of the flavonoid aglycon mixture, which did not affect frequency. None of the test substances decreased myometrial cell viability, even at concentrations of 500 µg/mL of the flavonoid-enriched fraction, 40 µg/mL of the flavonoid aglycon mixture, 3.8 µg/mL of the bufadienolide-enriched fraction, and 75 µg/mL of the B. pinnatum leaf press juice, i.e., higher than those used in the myometrium experiments. Given the concentrations of flavonoids in the flavonoid-enriched fraction and B. pinnatum leaf press juice, and of bufadienolides in the bufadienolide-enriched fraction and B. pinnatum leaf press juice, it appears that bufadienolides may be mainly responsible for the relaxant effect.

HPLC-Based Activity Profiling for GABAA Receptor Modulators in Murraya exotica

A dichloromethane extract from twigs and leaves of Murraya exotica produced allosteric potentiation of gamma aminobutyric acid (GABA) induced chloride currents in a microelectrode assay in Xenopus laevis oocytes expressing GABA receptors of α1, β2, γ2s subunit composition. The activity was tracked by HPLC-based activity profiling utilizing a zebrafish locomotor activity assay. Osthol (9) was identified as the main active compound. In addition, five other coumarins and four flavonols were identified. Osthol (9) and structurally related coumurrayin (10) were tested in the Xenopus oocyte assay. Compound 9 potentiated GABAA-induced chloride currents by 487 ± 42%, with an EC50 of 46 ± 10 μM, while 10 showed negligible effects on chloride currents. In silico evaluation of physicochemical properties showed that 9 and 10 had properties that are favorable for oral bioavailability and BBB permeability.

Antiprotozoal Isoprenoids from Salvia hydrangea

Fractionation of the n-hexane extract of Salvia hydrangea afforded seven isoprenoids including six new compounds (1-6) and salvadione A (7). Their structures were established by comprehensive spectroscopic and spectrometric data analysis (1D and 2D NMR, HRMS). The absolute configuration of salvadione A (7) was established by single-crystal X-ray diffraction analysis with Cu/Kα radiation. In addition, the absolute configuration of all compounds was determined by electronic circular dichroism spectroscopy. A biosynthetic pathway for the formation of the scaffold of 1 is proposed. The antiprotozoal activity of the compounds against Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum was determined, and cytotoxicity was assessed in rat myoblast L6 cells. Perovskone C (2) exhibited good activity against P. falciparum (IC₅₀ 0.6 μM) and a selectivity index of 62.2.

Antiprotozoal Diterpenes from Perovskia abrotanoides

As part of a screening for new antiparasitic natural products from Iranian plants, n-hexane and ethyl acetate extracts from the aerial parts of Perovskia abrotanoides were found to exhibit strong inhibitory activity against Trypanosoma brucei rhodesiense and Leishmania donovani. The activity was tracked by high-performance liquid chromatography (HPLC)-based activity profiling. Preparative isolation by a combination of silica gel column chromatography and HPLC afforded 17 diterpenoids (1: -17: ), including 14 abietane-, two icetexane-, and one isopimarane-type derivatives. Among these, (5R,10S)-11-hydroxy-12-methoxy-20-norabieta-8,11,13-triene (2: ), 12-hydroxy-norabieta-1(10),8,11,13-tetraene-1,11-furan (6: ), and 12-methoxybarbatusol (9: ) were new compounds, the structure of which was established by comprehensive spectroscopic data analysis (one- and two-dimensional nuclear magnetic resonance, high-resolution electrospray ionization mass spectrometry, electronic circular dichroism). The antiprotozoal activity of the isolated compounds was evaluated against T. b. rhodesiense, Trypanosoma cruzi, L. donovani, and Plasmodium falciparum. Selectivity indexes (SI) were calculated in comparison to cytotoxicity on rat myoblast (L6) cells. Particularly active were 7α-ethoxyrosmanol (4: ) with an IC₅₀ of 0.8 µM against T. b. rhodesiense (SI 14.9) and an IC₅₀ of 1.8 µM (SI 6.9) against L. donovani, ferruginol (8: ) with an IC₅₀ of 2.9 µM (SI 19.2) against P. falciparum, and miltiodiol (10: ) with an IC₅₀ of 0.5 µM (SI 10.5) against T. b. rhodesiense. None of the compounds exhibited selective toxicity against T. cruzi (SI ≤ 1.6).

In Vitro Anti-inflammatory Effects of Equisetum arvense Are Not Solely Mediated by Silica

Equisetum arvense, known as common horsetail, is used for the treatment of inflammatory diseases and is the plant with the highest concentration of silica. Yet it is unknown if the medicinal properties are mediated by its silica content. In the current study, optimal conditions for silica-rich horsetail preparations were identified. Bioactivity of the preparations was analyzed in vitro using flow cytometry-based activity and functionality profiling of primary human lymphocytes as well as cytokine measurement using a classical ELISA technique. Experiments revealed that horsetail preparations suppress activation and proliferation of lymphocytes by an interleukin-2-dependent mechanism. The effect increased with the silica concentration in the decoctions. Lymphocytes' polyfunctionality was also influenced, shown by a downregulation of IFN-γ. Analytical profiling by HPLC-UV-MS and bioactivity testing revealed relevant immunosuppressive concentrations of a component that has been identified as isoquercitrin. Our results show that both silica and isoquercitrin are active compounds of horsetail preparations.

Eudesmane Sesquiterpenes from Verbesina lanata with Inhibitory Activity against Grapevine Downy Mildew

An in-house library of more than 3000 extracts of plant and fungal origin was screened against some major plant pathogens. As one of the hits, an ethyl acetate extract from inflorescences of Verbesina lanata showed significant inhibitory activity in vitro against grapevine downy mildew (Plasmopara viticola), with a MIC₁₀₀ value of 35 μg/mL. An emulsifiable concentrate formulation with 50 mg/g of the extract was developed for in vivo evaluation. A suspension of the formulation containing 1 mg/mL of extract lowered leaf surface infection of grapevine seedling by 82% compared to the nontreated control. With the aid of HPLC-based activity profiling, the antifungal activity was correlated with a series of lipophilic compounds. Preparative isolation by a combination of chromatographic techniques afforded 16 eudesmane sesquiterpenes including eight new congeners. Nine compounds were obtained in sufficient quantities to be tested in vitro and were found to inhibit the zoospore activity of P. viticola with MIC₁₀₀ values ranging from 4 to 50 μg/mL. The two major compounds, 6β-cinnamoyloxy-4β,9β,15-trihydroxyeudesmane (9) and 6β-cinnamoyloxy-1β,15-dihydroxyeudesm-4-en-3-one (13), showed MIC₁₀₀ values of 5 and 31 μg/mL, respectively.

Potential of Bryophyllum pinnatum as a Detrusor Relaxant: An in Vitro Exploratory Study

An earlier prospective, randomised, placebo-controlled clinical trial had suggested that Bryophyllum pinnatum might have potential in the treatment of overactive bladder. Here we investigated the effects of B. pinnatum leaf press juice, fractions enriched in flavonoids and bufadienolides, and a flavonoid aglycon mixture and individual aglycons on detrusor contractility as a major target in overactive bladder treatment. The strength of the detrusor contractions was investigated using porcine muscle strips stimulated with KCl. B. pinnatum leaf press juice increased the contraction force of muscle strips. Treatment with the flavonoid-enriched fraction had almost no effect on contractility, while the bufadienolide-enriched fraction and flavonoid aglycons led to a concentration-dependent lowering of the contraction force. The data indicate that several components of B. pinnatum leaf press juice may contribute to the inhibitory effect on detrusor contractility, which in turn provides support to overactive bladder treatment with B. pinnatum.

Metabolite Profile and Antiproliferative Effects in HaCaT Cells of a Salix reticulata Extract

Phenolic constituents of Salix reticulata (Salicaceae) and antiproliferative activity of an extract and individual compounds were investigated in immortalized human non-tumorigenic keratinocytes (HaCaT). A MeOH extract from aerial parts afforded several flavonoids, including luteolin and apigenin glycosides (2-5 and 9) and catechin (1), two procyanidin fractions, and the phenolic glucosides picein (6), triandrin (7), and salicortin (8). In an adenosine triphosphate assay, the MeOH extract reduced cell viability by approximately 60 % at a concentration of 100 µg/mL. Cell proliferation was assessed with a BrdU incorporation ELISA assay. The extract inhibited proliferation of HaCaT cells in a concentration-dependent manner, with approximately 50 % inhibition at 100 µg/mL. In time-lapse assays, the extract showed distinct inhibitory effects on cell migration at concentrations of 12.5, 25, and 50 µg/mL. The activity of selected constituents was also determined. Luteolin-7-O-β-glucuronide (3) significantly inhibited cell proliferation at concentrations of 10 and 50 µM. In contrast, luteolin-7-O-β-glucopyranoside (2) and a procyanidin fraction (P1) had only weak effects, while picein (6) and salicortin (8) did not affect cell proliferation. Luteolin-7-O-β-glucuronide (10 µM) and, to a lesser extent, the procyanidin fraction (10 µg/mL) also inhibited cell migration.

Bryophyllum pinnatum – Reverse Engineering of an Anthroposophic Herbal Medicine

Bryophyllum pinnatum (syn. Kalanchoe pinnata), a plant native to Madagascar, was introduced into anthroposophic medicine in the early 20th century. In recent years, a number of investigations were conducted on the chemical composition, pharmacological properties, and clinical efficacy of Bryophyllum. Here the phytochemistry, and pharmacological and clinical data are reviewed. With respect to pharmacology, a special focus was put on properties related to the use in anthroposophic medicine as a treatment for “hyperactivity diseases”, including preterm labor, restlessness, and sleep disorders. Recent studies suggest that B. pinnatum has also potential as a treatment option in patients suffering from overactive bladder syndrome. Tolerability of Bryophyllum is addressed, and existing toxicological data are discussed in relation to bufadienolides contained in Bryophyllum. Open questions regarding the use of Bryophyllum are also discussed.

The Dual Edema-Preventing Molecular Mechanism of the Crataegus Extract WS 1442 Can Be Assigned to Distinct Phytochemical Fractions

The hawthorn (Crataegus spp.) extract WS 1442 is used against mild forms of chronic heart failure. This disease is associated with endothelial barrier dysfunction and edema formation. We have recently shown that WS 1442 protects against this dysfunction by a dual mechanism: it both promotes endothelial barrier integrity by activation of a barrier-enhancing pathway (cortactin activation) and inhibits endothelial hyperpermeability by blocking a barrier disruptive pathway (calcium signaling). In this study, we aimed to identify the bioactive compounds responsible for these actions by using a bioactivity-guided fractionation approach. From the four fractions generated from WS 1442 by successive elution with water, 95 % ethanol, methanol, and 70 % acetone, only the water fraction was inactive, whereas the other three triggered a reduction of endothelial hyperpermeability. Analyses of intracellular calcium levels and cortactin phosphorylation were used as readouts to estimate the bioactivity of subfractions and isolated compounds. Interestingly, only the ethanolic fraction interfered with the calcium signaling, whereas only the methanolic fraction led to an activation of cortactin. Thus, the dual mode of action of WS 1442 could be clearly assigned to two distinct fractions. Although the identification of the calcium-active substance(s) was not successful, we could exclude an involvement of phenolic compounds. Cortactin activation, however, could be clearly attributed to oligomeric procyanidins with a distinct degree of polymerization. Taken together, our study provides the first approach to identify the active constituents of WS 1442 that address different cellular pathways leading to the inhibition of endothelial barrier dysfunction.

Efficacy of a Juncus effusus extract on grapevine and apple plants against Plasmopara viticola and Venturia inaequalis, and identification of the major active constituent

BACKGROUND

There is growing demand to replace chemical pesticides with alternatives owing to concerns related to impacts on human health and the environment. Plant-derived plant protection products could provide sustainable and environmentally friendly alternatives to chemical products. The aim of this study was to identify plant and fungal extracts with so far unknown activity against important plant pathogens by in vitro screening of a library of more than 3000 extracts.

RESULTS

Several plant extracts with promising in vitro fungicidal activity (MIC100 ≤ 50 µg mL(-1) ) towards one or several of the investigated pathogens (Venturia ineaqualis, Phytophthora infestans, Plasmopara viticola) were identified by the screening. One of the hits, an ethyl acetate extract of Juncus effusus L. medulla, was further investigated, and dehydroeffusol (DHEF) was identified as its main active constituent. On susceptible grapevine and apple seedlings, efficacies of up to 100% were reached with the extract (EC50 123 or 156 µg mL(-1) ) and with DHEF (EC50 18 or 21 µg mL(-1) ) against P. viticola and V. inaequalis respectively.

CONCLUSIONS

Our results demonstrate that plants can provide promising alternatives for integrated and organic farming. J. effusus shows high efficacy at low concentrations and, as an abundant perennial species, is an interesting candidate for the development of a novel plant protection product. © 2015 Society of Chemical Industry.

Bryophyllum pinnatum and Related Species Used in Anthroposophic Medicine: Constituents, Pharmacological Activities, and Clinical Efficacy

Bryophyllum pinnatum (syn. Kalanchoe pinnata) is a succulent perennial plant native to Madagascar that was introduced in anthroposophic medicine in the early 20th century. In recent years, we conducted a large collaborative project to provide reliable data on the chemical composition, pharmacological properties, and clinical efficacy of Bryophyllum. Here, we comprehensively review the phytochemistry, as well as the pharmacological and clinical data. As to the pharmacology, special emphasis is given to properties related to the use in anthroposophic medicine as a treatment for "hyperactivity diseases", such as preterm labor, restlessness, and sleep disorders. Studies suggesting that B. pinnatum may become a new treatment option for overactive bladder syndrome are also reviewed. Tolerability is addressed, and toxicological data are discussed in conjunction with the presence of potentially toxic bufadienolides in Bryophyllum species. The few data available on two related species with medicinal uses, Bryophyllum daigremontianum and Bryophyllum delagoense, have also been included. Taken together, current data support the use of B. pinnatum for the mentioned indications, but further studies are needed to fully understand the modes of action, and to identify the pharmacologically active constituents.

A New Secoiridoid Glucoside, and a Metabolite Profile of Scabiosa lucida

Fourteen secondary metabolites, including a new secoiridoid glucoside (1), were isolated from the aerial parts of Scabiosa lucida by a combination of column chromatography, preparative and semi-preparative HPLC. They were identified by extensive NMR, and ESI-MS experiments, and by comparison with literature data.

New Secoiridoid Glucoside, and a Metabolite Profile of Scabiosa lucida

ourteen secondary metabolites, including a new secoiridoid glucoside (1), were isolated from the aerial parts of Scabiosa licida by a combination of column hromatography, preparative and semi-preparative HPLC. They were identified by extensive NMR, and ESI-MS experiments, and by comparison with iterature data.

Identification of Plant-derived Alkaloids with Therapeutic Potential for Myotonic Dystrophy Type I

Myotonic dystrophy type I (DM1) is a disabling neuromuscular disease with no causal treatment available. This disease is caused by expanded CTG trinucleotide repeats in the 3' UTR of the dystrophia myotonica protein kinase gene. On the RNA level, expanded (CUG)n repeats form hairpin structures that sequester splicing factors such as muscleblind-like 1 (MBNL1). Lack of available MBNL1 leads to misregulated alternative splicing of many target pre-mRNAs, leading to the multisystemic symptoms in DM1. Many studies aiming to identify small molecules that target the (CUG)n-MBNL1 complex focused on synthetic molecules. In an effort to identify new small molecules that liberate sequestered MBNL1 from (CUG)n RNA, we focused specifically on small molecules of natural origin. Natural products remain an important source for drugs and play a significant role in providing novel leads and pharmacophores for medicinal chemistry. In a new DM1 mechanism-based biochemical assay, we screened a collection of isolated natural compounds and a library of over 2100 extracts from plants and fungal strains. HPLC-based activity profiling in combination with spectroscopic methods were used to identify the active principles in the extracts. The bioactivity of the identified compounds was investigated in a human cell model and in a mouse model of DM1. We identified several alkaloids, including the β-carboline harmine and the isoquinoline berberine, that ameliorated certain aspects of the DM1 pathology in these models. Alkaloids as a compound class may have potential for drug discovery in other RNA-mediated diseases.