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Planta medica [journal]
- Assay Suitability for Natural Product Screening: Searching for Leads to Fight Alzheimer's Disease. [JOURNAL ARTICLE]
- Planta Med 2014 Sep 15.
Phenotypic and target-based approaches represent two principal strategies for identifying new bioactive compounds. In this review, differences between these approaches, as well as strengths and limitations thereof, are described by examples from the therapeutic area of Alzheimer's disease. Some of the central mechanisms of the disease that today are targets of screening campaigns are described. These mechanisms include acetylcholinesterase inhibition, amyloid-based approaches, and oxidative stress. Examples of assays using natural products, either as isolated pure compounds, unpurified or partially purified extracts, are given for each mechanism. Further, the article presents and discusses the pros and cons of both target-based and phenotypic approaches for the chosen mechanisms. In most cases, a thoroughly biology-driven selection of the used assays can be recommended, especially when taking into account the complexity of the disease in question. However, target-based assays also have their justification as long as there is an awareness of what the assay read-out stands for. A clear recommendation is thus for every researcher to critically consider the aim of their bioactivity screening efforts and to adopt the screening strategies most appropriate for the goals set.
- How to Translate a Bioassay Into a Screening Assay for Natural Products: General Considerations and Implementation of Antimicrobial Screens. [JOURNAL ARTICLE]
- Planta Med 2014 Sep 15.
Natural product sources have been a valuable provider of molecular diversity in many drug discovery programs and several therapeutically important drugs have been isolated from these. However, the screening of such materials can be very complicated due to the fact that they contain a complex mixture of secondary metabolites, but also the purified natural compounds exert a challenge for bioactivity screening. Success in identifying new therapeutics using in vitro bioassays is largely dependent upon the proper design, validation, and implementation of the screening assay. In this review, we discuss some aspects which are of significant concern when screening natural products in a microtiter plate-based format, being partly applicable to other assay formats as well, such as validation parameters, layouts for assay protocols, and common interferences caused by natural products samples, as well as various troubleshooting strategies. Examples from the field of natural product drug discovery of antibacterial compounds are discussed, and contributions from the realm of academic screenings are highlighted.
- Extracts from Rhododendron ferrugineum Do Not Exhibit Grayanotoxin I: An Analytical Survey on Grayanotoxin I within the Genus Rhododendron. [JOURNAL ARTICLE]
- Planta Med 2014 Sep 12.
For quantitative determination of grayanotoxin I (1) in plant material, a GC/MS method was developed after trimethylsilyl derivatisation of the analytes. Forskolin (5) was used as an internal standard for quantification. ICH-compliant method validation indicated sufficient specificity, precision, quantitation (15 µg/mL) and detection (5 µg/mL) limits. Regression analysis showed that a non-linear (polynomial) model was preferable to a linear one. For isolation of grayanotoxin I reference material from Rhododendron ponticum leaves, an efficient two-step fast centrifugal partition chromatography isolation protocol is described. A survey of 17 different plant species from the genus Rhododendron revealed high grayanotoxin I content for R. catawbiense, R. ponticum, R. degronianum subsp. yakushimanum, R. × sochadzeae, R. moupinense, R. galactinum, and R. mucronatum var. ripense. The content of this compound in leaf material from R. ponticum decreased rapidly during drying process. Grayanotoxin I was not detected in different batches of fresh leaves and fruits from R. ferrugineum. In contrast to the claims of German health authorities, this traditionally used herb therefore cannot be evaluated as toxic due to the presence of grayanotoxin I.
- Mechanisms of Action of Phytochemicals from Medicinal Herbs in the Treatment of Alzheimer's Disease. [JOURNAL ARTICLE]
- Planta Med 2014 Sep 11.
Alzheimer's disease is a chronic neurodegenerative disorder characterized by progressive dementia and deterioration of cognitive function. Although several drugs currently used for the treatment of Alzheimer's disease delay its onset and slow its progression, still there is no drug with profound disease-modifying effects. Studies aiming the treatment of this neurodegenerative disorder explore various disease mechanisms. Since antiquity, medicinal herbs have been used in traditional medicine. Recent studies suggest that the neurobiological effects of phytochemicals from medicinal herbs may contribute to clinical benefits in in vitro and in vivo models of Alzheimer's disease. This review focuses on five phytochemicals, berberine, curcumin, ginsenoside Rg1, puerarin, and silibinin, which have been mostly investigated to treat the development and progression of this neurodegenerative disorder.
- Exploring Marine Resources for Bioactive Compounds. [JOURNAL ARTICLE]
- Planta Med 2014 Sep 9.
Biodiversity in the seas is only partly explored, although marine organisms are excellent sources for many industrial products. Through close co-operation between industrial and academic partners, it is possible to successfully collect, isolate and classify marine organisms, such as bacteria, fungi, micro- and macroalgae, cyanobacteria, and marine invertebrates from the oceans and seas globally. Extracts and purified compounds of these organisms can be studied for several therapeutically and industrially significant biological activities, including anticancer, anti-inflammatory, antiviral, antibacterial, and anticoagulant activities by applying a wide variety of screening tools, as well as for ion channel/receptor modulation and plant growth regulation. Chromatographic isolation of bioactive compounds will be followed by structural determination. Sustainable cultivation methods for promising organisms and biotechnological processes for selected compounds can be developed, as well as biosensors for monitoring the target compounds. The (semi)synthetic modification of marine-based bioactive compounds produces their new derivatives, structural analogs and mimetics that could serve as hit or lead compounds and be used to expand compound libraries based on marine natural products. The research innovations can be targeted for industrial product development in order to improve the growth and productivity of marine biotechnology. Marine research aims at a better understanding of environmentally conscious sourcing of marine biotechnology products and increased public awareness of marine biodiversity. Marine research is expected to offer novel marine-based lead compounds for industries and strengthen their product portfolios related to pharmaceutical, nutraceutical, cosmetic, agrochemical, food processing, material and biosensor applications.
- Thymbra capitata Essential Oil Prevents Cell Death Induced by 4-Hydroxy-2-Nonenal in Neonatal Rat Cardiac Myocytes. [JOURNAL ARTICLE]
- Planta Med 2014 Sep 9.
An interdisciplinary experimental investigation on the antioxidant activity of Thymbra capitata essential oil was made. This plant is a Mediterranean culinary herb, whose essential oil antioxidant power has recently been demonstrated in vitro as one of the highest in nature. We tested if this in vitro antioxidant capacity was reproducible on biological systems using as model system primary cultures of neonatal rat cardiomyocytes treated with the lipid peroxidation product 4-hydroxy-2-nonenal. The composition and the in vitro antioxidant activity of the T. capitata essential oil were also assessed. Cell viability, mitochondrial membrane potential, and reactive oxygen species level were measured in cells treated with pathophysiologic doses of 4-hydroxy-2-nonenal (< 10 µM) or vehicle after being pre-incubated with small concentrations of the T. capitata essential oil, and the ability of small doses (< 40 ppm) to prevent the death of neonatal rat cardiomyocytes proved very remarkable. Long-term pre-incubation (12 h) with 20 ppm prevented 4-hydroxy-2-nonenal-induced cell death and avoided mitochondrial membrane potential loss and reactive oxygen species generation caused by 4-hydroxy-2-nonenal. A deleterious effect was shown at doses higher than 40 ppm. The results of this study pave the way to further analysis in animal models to achieve a deeper understanding of the in vivo antioxidant power of T. capitata essential oil.
- Establishment of an enzyme-linked immunosorbent assay and application on determination of ginsenoside re in human saliva. [Journal Article]
- Planta Med 2014 Aug; 80(13):1143-50.
This work describes an immunochemical approach for the quality control of Panax ginseng and a pharmacological study of ginsenoside Re, a major bioactive constituent in P. ginseng, using an enzyme-linked immunosorbent assay. A hybridoma secreting monoclonal antibody against ginsenoside Re was produced by fusing splenocytes immunized with a ginsenoside Re-bovine serum albumin conjugate with the hypoxanthine-aminopterin-thymidine-sensitive mouse myeloma SP2/0 cell line. The method, at an effective measuring range of 7.8-500 ng · mL(-1) of ginsenoside Re, successfully detected ginsenoside Re in Chinese traditional herb prescriptions. The results demonstrate that we generated a novel and reliable assay system for measuring ginsenoside Re in Chinese medicines more efficiently. Futhermore, we determined the ginsenoside Re concentrations in the saliva of six healthy adults after the oral administration of a ginseng capsule to study the pharmacokinetics of ginsenoside Re in human saliva.
- Inhibition of Cytochrome P450 2C9 Expression and Activity In Vitro by Allyl Isothiocyanate. [Journal Article]
- Planta Med 2014 Aug; 80(13):1097-106.
The growing interest in the use of natural herbal products and dietary supplements to treat and prevent diseases raises the question of medicinal drug safety. Allyl isothiocyanate, a hydrolysis product of a glucosinolate, sinigrin, has multiple beneficial properties, and based on this fact, allyl isothiocyanate-containing dietary supplements have been developed. To date, no studies of the effects of this compound on the cytochrome P450 2C9 have been reported. In this study, we found that allyl isothiocyanate reduced catalytic activity, messenger ribonucleic acid, and protein expression of cytochrome P450 2C9 in HepaRG cells. An investigation of the transcriptional activity of the pregnane X receptor and the constitutive androstane receptor revealed that allyl isothiocyanate disrupted the transcriptional coregulation effects of the pregnane X receptor/constitutive androstane receptor with several important coregulators and interfered with the assembly of transcriptional complexes of the cytochrome P450 2C9 pregnane X receptor/constitutive androstane receptor-response element. The decrease of cytochrome P450 2C9 expression and activity mediated by allyl isothiocyanate suggested that this agent could alter the metabolism of drugs metabolized by cytochrome P450 2C9. This may cause food/dietary supplement-drug interactions or alter the therapeutic effects, and even the toxicity of drugs coadministered with allyl isothiocyanate. Since the consumption of allyl isothiocyanate-containing food/dietary supplements continues to increase, it is important to predict and ultimately avoid interactions with concomitant drugs. It is required that these possible pharmacokinetic interactions be characterized and the recommendations available to patients and healthcare professionals be improved.
- Curine, an Alkaloid Isolated from Chondrodendron platyphyllum Inhibits Prostaglandin E2 in Experimental Models of Inflammation and Pain. [Journal Article]
- Planta Med 2014 Aug; 80(13):1072-8.
Curine is a bisbenzylisoquinoline alkaloid that is isolated from Chondrodendron platyphyllum, a plant that is used to treat malaria, inflammation, and pain. Recent reports have demonstrated the antiallergic effects of curine at nontoxic doses. However, its anti-inflammatory and analgesic properties remain to be elucidated. This study investigated the anti-inflammatory and analgesic effects of curine in mice. We analyzed the effects of an oral treatment with curine in the formation of paw edema, vascular permeability, abdominal contortion, licking behavior, and hyperalgesia using different inflammatory stimuli. Curine significantly inhibited the formation of paw edema by decreasing vascular permeability, inhibited the acetic acid-induced writhing response, inhibited the licking behavior during inflammation but not during the neurogenic phase of the formalin test, and inhibited carrageenan-induced hyperalgesia. Finally, curine inhibited prostaglandin E2 production in vitro without affecting cyclooxygenase-2 expression. The effects of curine treatment were similar to the effects of indomethacin, but were different from the effects of morphine treatment, suggesting that the analgesic effects of curine do not result from the direct inhibition of neuronal activation but instead depend on anti-inflammatory mechanisms that, at least in part, result from the inhibition of prostaglandin E2 production. In conclusion, curine presents anti-inflammatory and analgesic effects at nontoxic doses and has the potential for use in anti-inflammatory drug development.
- Skullcap and Germander: Preventing Potential Toxicity through the Application of Hyperspectral Imaging and Multivariate Image Analysis as a Novel Quality Control Method. [JOURNAL ARTICLE]
- Planta Med 2014 Sep 3.
Scutellaria lateriflora (skullcap) is a medicinal herb that has a long history of use in the treatment of ailments such as insomnia and anxiety. Commercial herbal formulations claiming to contain S. laterifolia herba have flooded the consumer markets. However, due to intentional or unintentional adulteration, cases of hepatotoxicity have been reported. Possible adulteration with the potentially hepatotoxic Teucrium spp., T. canadense and T. chamaedrys has been reported. In this study, hyperspectral imaging in combination with multivariate image analysis methods was used to differentiate S. laterifolia, T. canadense, and T. chamaedrys raw materials in a non-destructive manner. Furthermore, the ability to detect adulteration of raw materials using the developed multivariate models was also investigated. Chemical images were captured using a shortwave infrared pushbroom imaging system in the wavelength range 920-2514 nm. Principal component analysis was applied to the images to investigate chemical differences between the species. Partial least squares discriminant analysis was used to model pre-assigned class images, and the classification model predicted the levels of adulteration in spiked raw materials. UHPLC-MS as an independent analytical technique was used to confirm chemical differences between the three species. The ability of hyperspectral chemical imaging as a non-destructive technique in the differentiation of the three species was achieved with three distinct clusters in the score scatter plot. A 92.3 % variation in modelled data using PC1 and PC2 was correlated to chemical differences between the three species. Near infrared signals in the regions 1924 nm and 2092 nm (positive P1), 1993 nm and 2186 nm (negative P1), 1918 nm, 2092 nm, and 2266 nm (positive P2), as well as 1993 nm and 2303 nm (negative P2) were identified as containing discriminating information using the loadings line plots. Chemical imaging of spiked samples showed spatial orientation of contaminants within the powdered samples, and percentage adulteration was accurately predicted at levels ≥ 40 % adulteration based on pixel abundance.