Bioassay-guided isolation of aldose reductase inhibitors from Artemisia dracunculus

LC-PDA-ESI/MS Identification of the Phenolic Components of Three Compositae Spices: Chamomile, Tarragon, and Mexican Arnica

Chamomile ( Matricaria chamomilla L.), tarragon ( Artemisia dracunculus L.) and Mexican arnica ( Heterotheca inuoides) are common compositae spices and herbs found in the US market. They contain flavonoids and hydroxycinnamates that are potentially beneficial to human health. A standardized LC-PDA-ESI/MS profiling method was used to identify 51 flavonoids and 17 hydroxycinnamates. Many of the identifications were confirmed with authentic standards or through references in the literature or the laboratory's database. More than half of the phenol compounds for each spice had not been previously reported. The phenolic profile can be used for plant authentication and to correlate with biological activities.

Effective cytochrome P450 (CYP) inhibitors isolated from tarragon (Artemisia dracunculus)

Two effective cytochrome P450 (CYP) inhibitors were isolated from tarragon, Artemisia dracunculus. Their structures were spectroscopically identified as 2E,4E-undeca-2,4-diene-8,10-diynoic acid isobutylamide (1) and 2E,4E-undeca-2,4-diene-8,10-diynoic acid piperidide (2). Both compounds had dose-dependent inhibitory effects on CYP3A4 activity with IC50 values of 10.0 ± 1.3 µM for compound 1 and 3.3 ± 0.2 µM for compound 2, and exhibited mechanism-based inhibition. This is the first reported isolation of effective CYP inhibitors from tarragon (Artemisia dracunculus) purchased from a Japanese market.

Proteomic analysis reveals cellular pathways regulating carbohydrate metabolism that are modulated in primary human skeletal muscle culture due to treatment with bioactives from Artemisia dracunculus L

Insulin resistance is a major pathophysiologic abnormality that characterizes metabolic syndrome and type 2 diabetes. A well characterized ethanolic extract of Artemisia dracunculus L., termed PMI 5011, has been shown to improve insulin action in vitro and in vivo, but the cellular mechanisms remain elusive. Using differential proteomics, we have studied mechanisms by which PMI 5011 enhances insulin action in primary human skeletal muscle culture obtained by biopsy from obese, insulin-resistant individuals. Using iTRAQ™ labeling and LC-MS/MS, we have identified over 200 differentially regulated proteins due to treatment with PMI 5011 and insulin stimulation. Bioinformatics analyses determined that several metabolic pathways related to glycolysis, glucose transport and cell signaling were highly represented and differentially regulated in the presence of PMI 5011 indicating that this extract affects several pathways modulating carbohydrate metabolism, including translocation of GLUT4 to the plasma membrane. These findings provide a molecular mechanism by which a botanical extract improves insulin stimulated glucose uptake, transport and metabolism at the cellular level resulting in enhanced whole body insulin sensitivity.

Artemisia dracunculus L. (tarragon): a critical review of its traditional use, chemical composition, pharmacology, and safety

Artemisia dracunculus L. (tarragon) has a long history of use as a spice and remedy. Two well-described "cultivars" (Russian and French) are used widely and differ in ploidy level, morphology, and chemistry. Key biologically active secondary metabolites are essential oils (0.15-3.1%), coumarins (>1%), flavonoids, and phenolcarbonic acids. In vivo studies mainly in rodents, particularly from Russian sources, highlight potential anti-inflammatory, hepatoprotective, and antihyperglycemic effects. Despite concerns about the toxic effects of two of its main constituents, estragole (up to 82%) and methyleugenol (up to 39%), no acute toxicity or mutagenic activity has been reported at doses relevant for human consumption. Water extracts of A. dracunculus contain very low amounts of estragole and methyleugenol and, therefore, are considered to pose a very limited risk. Overall, a stronger focus on clinical studies and precise taxonomic and phytochemical definition of the source material will be essential for future research efforts.

Qualitative variation of anti-diabetic compounds in different tarragon (Artemisia dracunculus L.) cytotypes

Ethanolic extracts of diploid Artemisia dracunculus L. (wild tarragon) from populations in the U.S., and polyploid tarragon from a variety of sources, were screened for the anti-diabetic compounds davidigenin; sakuranetin; 2',4'-dihydroxy-4-methoxydihydrochalcone; 4,5-di-O-caffeoylquinic acid; 5-O-caffeoylquinic acid and 6-demethoxycapillarisin using LC-MS. Only decaploid plants contained all six target compounds and were the only plants that contained davidigenin and 2,4-dihydroxy-4-methoxydihydrochalcone. These results exhibit the importance of germplasm selection and provenance when studying plants for medicinal activity. Relying only on the "right species" for consistent medicinal activities may not be sufficient, as intraspecific variation may be highly significant.

Evaluation of PMI-5011, an ethanolic extract of Artemisia dracunculus L., on peripheral neuropathy in streptozotocin-diabetic mice

We previously reported that PMI-5011, an ethanolic extract of Artemisia dracunculus L., alleviates peripheral neuropathy in high fat diet-fed mice, a model of prediabetes and obesity developing oxidative stress and pro-inflammatory changes in the peripheral nervous system. This study evaluated PMI-5011 on established functional, structural, and biochemical changes associated with Type I diabetic peripheral neuropathy. C57Bl6/J mice with streptozotocin-induced diabetes of a 12-week duration, developed motor and sensory nerve conduction velocity deficits, thermal and mechanical hypoalgesia, tactile allodynia, and intra-epidermal nerve fiber loss. PMI-5011 (500 mg/kg/day for 7 weeks) alleviated diabetes-induced nerve conduction slowing, small sensory nerve fiber dysfunction, and increased intra-epidermal nerve fiber density. PMI-5011 blunted sciatic nerve and spinal cord 12/15-lipoxygenase activation and oxidative-nitrosative stress, without ameliorating hyperglycemia or reducing sciatic nerve sorbitol pathway intermediate accumulation. In conclusion, PMI-5011, a safe and non-toxic botanical extract, may find use in the treatment of diabetic peripheral neuropathy.

Molecular mechanisms for activation of the agouti-related protein and stimulation of appetite

OBJECTIVE

The agouti-related protein (Agrp) is a powerful orexigenic peptide, but little is known about its transcriptional regulation. The objective of this study was to determine molecular mechanisms for the activation of hypothalamic Agrp and identify compounds that stimulate appetite.

RESEARCH DESIGN AND METHODS

We used promoter analyses methods, hypothalamic cell culture and transfection, immunohistochemistry, luciferase-expressing transgenic mice, in vivo bioluminescence, anitisense RNA, mouse feeding studies, indirect calorimetry, real-time PCR, and Western blots.

RESULTS

We found that the Krüppel-like factor 4 (Klf4) is a potent activator of Agrp by binding to a specific CACCC-box in its minimal promoter. We also found that an extract of tarragon, termed PMI-5011, activated hypothalamic Klf4 and Agrp. In vivo, PMI-5011 increased Agrp promoter activity in luciferase-expressing transgenic mice, increased hypothalamic Klf4 and Agrp expression, increased hypothalamic Orexin and melanin-concentrating hormone, increased food intake, reduced circulating insulin and leptin levels, attenuated energy expenditure, and enhanced body weight but only when using a high-fat diet.

CONCLUSIONS

These data show that Klf4 augmented hypothalamic Agrp by binding to a specific CACCC-box onto its minimal promoter. In addition, the tarragon extract PMI-5011 activated Klf4 and orexigenic neuropeptides and reduced peripheral insulin and leptin levels leading to positive energy balance.

Antispasmodic and antioxidant activities of fractions and bioactive constituent davidigenin isolated from Mascarenhasia arborescens

ETHNOPHARMACOLOGICAL RELEVANCE

Mascarenhasia arborescens A. DC. (Apocynaceae) is used in traditional medicine in the North of Madagascar to treat intestinal disorders, intestinal spasms and diarrhoea.

AIM OF THE STUDY

The main objective of this work was to evaluate the antispasmodic activity of the crude methanolic extract of Mascarenhasia arborescens and of its four partitions and to identify the effective compound responsible for this effect.

MATERIALS AND METHODS

Isolation and structure elucidation techniques were performed in order to identify the bioactive constituent of Mascarenhasia arborescens and HPLC analysis was used for its quantification. Total phenolic content (TPC) of crude extracts and partitions were determined using the Folin-Ciocalteu method. Crude methanolic extract, partitions and the bioactive compound were investigated for their spasmolytic activity on several isolated organs. Their antiradical activity was also investigated by the DPPH test.

RESULTS

Bioassay-guided fractionation using isolated guinea pig ileum pre-contracted with histamine 3x10(-6) M led to the isolation of davidigenin (DG), a dihydrochalcone, as the main active constituent from the most promising methylene chloride partition (McP). This partition was effective on isolated guinea pig ileum pre-contracted with 3x10(-6) M histamine, with a median effective concentration (EC(50)) of 41.19+/-3.74 microg/ml. The DG content of this partition was shown to be 26.5% by HPLC. DG induced a concentration-dependent relaxation of the histamine pre-contracted guinea pig ileum with an EC(50) of 8.04+/-0.81 microg/ml and a concentration-dependent relaxation of the acetylcholine pre-contracted rat duodenum with an EC(50) of 9.35+/-0.30 microg/ml. It inhibited in a non-competitive manner histamine-induced isolated ileum contraction and the acetylcholine-induced isolated duodenum contraction. Moreover, DG does not have any antiradical activity.

CONCLUSIONS

We demonstrated for the first time antispasmodic and antioxidant effects of Mascarenhasia arborescens. This study supports its use in traditional medicine. Furthermore, we highlighted the crucial role of davidigenin in the antispasmodic activity of this plant.

An extract of Artemisia dracunculus L. enhances insulin receptor signaling and modulates gene expression in skeletal muscle in KK-A(y) mice

An ethanolic extract of Artemisia dracunculus L. (PMI 5011) has been observed to decrease glucose and insulin levels in animal models, but the cellular mechanisms by which insulin action is enhanced in vivo are not precisely known. In this study, we evaluated the effects of PMI 5011 to modulate gene expression and cellular signaling through the insulin receptor in skeletal muscle of KK-A(y) mice. Eighteen male KK-A(y) mice were randomized to a diet (w/w) mixed with PMI 5011 (1%) or diet alone for 8 weeks. Food intake, adiposity, glucose and insulin were assessed over the study, and at study completion, vastus lateralis muscle was obtained to assess insulin signaling parameters and gene expression. Animals randomized to PMI 5011 were shown to have enhanced insulin sensitivity and increased insulin receptor signaling, i.e., IRS-associated PI-3 kinase activity, Akt-1 activity and Akt phosphorylation, in skeletal muscle when compared to control animals (P<.01, P<.01 and P<.001, respectively). Gene expression for insulin signaling proteins, i.e., IRS-1, PI-3 kinase and Glut-4, was not increased, although a relative increase in protein abundance was noted with PMI 5011 treatment. Gene expression for specific ubiquitin proteins and specific 20S proteasome activity, in addition to skeletal muscle phosphatase activity, i.e., PTP1B activity, was significantly decreased in mice randomized to PMI 5011 relative to control. Thus, the data demonstrate that PMI 5011 increases insulin sensitivity and enhances insulin receptor signaling in an animal model of insulin resistance. PMI 5011 may modulate skeletal muscle protein degradation and phosphatase activity as a possible mode of action.

High-fat diet-induced neuropathy of prediabetes and obesity: effect of PMI-5011, an ethanolic extract of Artemisia dracunculus L

Artemisia species are a rich source of herbal remedies with antioxidant and anti-inflammatory properties. We evaluated PMI-5011, an ethanolic extract of Artemisia dracunculus L., on neuropathy in high-sfat diet-fed mice, a model of prediabetes and obesity developing oxidative stress and proinflammatory changes in peripheral nervous system. C57Bl6/J mice fed high-fat diet for 16 weeks developed obesity, moderate nonfasting hyperglycemia, nerve conduction deficit, thermal and mechanical hypoalgesia, and tactile allodynia. They displayed 12/15-lipoxygenase overexpression, 12(S)-hydroxyeicosatetraenoic acid accumulation, and nitrosative stress in peripheral nerve and spinal cord. PMI-5011 (500 mgkg⁻¹d⁻¹, 7 weeks) normalized glycemia, alleviated nerve conduction slowing and sensory neuropathy, and reduced 12/15-lipoxygenase upregulation and nitrated protein expression in peripheral nervous system. PMI-5011, a safe and nontoxic botanical extract, may find use in treatment of neuropathic changes at the earliest stage of disease.

Bioassay guided discovery of apoptosis inducers from gamboge by high-speed counter-current chromatography and high-pressure liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry

A screening system, composed of high-speed counter-current chromatography and high-pressure liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry, was established to find bioactive lead compound. This system succeeded in discovering apoptosis inducers from gamboge, the resin of Garcinia hanburyi. High-speed counter-current chromatography was used to provide well-separated fractions for bioassay and the resulted active fractions were rapidly identified using high-pressure liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry. The solvent system of n-hexane/ethyl acetate/methanol/water was optimized to the ratio of 7:3:7:3 (v/v/v/v) by a K value analysis. As a result, two active fractions were obtained. They showed apoptosis inducing effects as potent as that of taxol (500 nM) at the concentration of 1 microg/ml. Gambogenic acid (72.1%) and epimeric isogambogic acids (25.3%) were identified in one of the fractions. The other active fraction mainly contained two epimeric mixtures, gambogic acids (68.7%) and gambogoic acids (26.9%). Among them, gambogenic acid, without epimerization, has priority to be lead compound.

Improved absorption and bioactivity of active compounds from an anti-diabetic extract of Artemisia dracunculus L

An ethanolic extract of Artemisia dracunculus L. (PMI-5011) was shown to be hypoglycemic in animal models for Type 2 diabetes and contains at least 6 bioactive compounds responsible for its anti-diabetic properties. To evaluate the bioavailability of the active compounds, high fat dietary induced obese C57BL/6J male mice were gavaged with PMI-5011 at 500mg/kg body weight, after 4h of food restriction. Blood plasma samples (200uL) were obtained after ingestion, and the concentrations of the active compound in the blood sera were measured by electrospray LC-MS and determined to be maximal 4-6h after gavage. Formulations of the extract with bioenhancers/solubilizers were evaluated in vivo for hypoglycemic activity and their effect on the abundance of active compounds in blood sera. At doses of 50-500mg/kg/day, the hypoglycemic activity of the extract was enhanced 3-5-fold with the bioenhancer Labrasol, making it comparable to the activity of the anti-diabetic drug metformin. When combined with Labrasol, one of the active compounds, 2', 4'-dihydroxy-4-methoxydihydrochalcone, was at least as effective as metformin at doses of 200-300mg/kg/day. Therefore, bioenhancing agents like Labrasol can be used with multicomponent botanical therapeutics such as PMI-5011 to increase their efficacy and/or to reduce the effective dose.

Constituents of the flowers of Erigeron annuus with inhibitory activity on the formation of advanced glycation end products (AGEs) and aldose reductase

Seven phenolic compounds, caffeic acid (1), 4-hydroxybenzoic acid (2), 4-methoxybenzoic acid (3), protocatechuic acid (4), eugenol O-beta-D: -glucopyranoside (5), 3,6-di-O-feruloylsucrose (6), and 3,5-di-O-caffeoylquinic acid methyl ester (7), were isolated from an EtOAc-soluble partition of the flowers of Erigeron annuus. The structures of 1-7 were determined by spectroscopic data interpretation, particularly 1D and 2D NMR studies, and by comparison of their data with those published in the literature. All the isolates were subjected to in vitro bioassays to evaluate their inhibitory activities against the formation of advanced glycation end products (AGEs) and rat lens aldose reductase (RLAR). Of the compounds, 1, 6, and 7 exhibited potent inhibitory activities against the formation of AGEs. In the RLAR assay, compound 7 showed the most potent inhibitory activity.

Quercetin transiently increases energy expenditure but persistently decreases circulating markers of inflammation in C57BL/6J mice fed a high-fat diet

Quercetin, a polyphenolic compound and a major bioflavonoid in the human diet, has anti-inflammatory properties and has been postulated to enhance energy expenditure (EE). We sought to determine whether quercetin alters body weight, body composition, EE, and circulating markers of inflammation. At 6 weeks (W) of age, 2 cohorts of C57BL/6J mice (N = 80) were placed on one of 2 diets for 3W or 8W: (1) high fat (HF) (45% kcal fat) or (2) high fat + quercetin (HF + Q) (45% kcal fat + 0.8% quercetin). Quercetin concentrations in the diet and plasma were evaluated using mass spectrometry. Body weight, composition (nuclear magnetic resonance), and food consumption were measured weekly. Energy expenditure was measured by indirect calorimetry at 3 and 8W, and inflammatory markers were measured in plasma obtained at 8W. The presence of quercetin in the HF diet did not alter food consumption over time in the HF + Q group and did not differ from the HF group at any time point. However, circulating plasma quercetin concentrations declined between 3 and 8W. At 3W, EE was higher during both day and night phases (P < .0001) in the HF + Q group compared with the HF group; but this difference was not detected at 8W and did not translate into significant differences between the HF + Q and HF groups with respect to body weight or body composition. During the night phase, concentrations of the inflammatory markers (interferon-gamma, interleukin-1alpha, and interleukin-4) were significantly lower when compared with HF treatment group (P < .05). Dietary supplementation with quercetin produces transient (3W) increases in EE that are not detected after 8W on the diet. A corresponding decrease in circulating quercetin between 3 and 8W suggests that metabolic adaptation may have diminished the impact of quercetin's early effect on EE and diminished its overall effect on nutrient partitioning and adiposity. However, quercetin at the levels provided was effective in reducing circulating markers of inflammation observed in animals on an HF diet at 8W.

A natural history of botanical therapeutics

Plants have been used as a source of medicine throughout history and continue to serve as the basis for many pharmaceuticals used today. Although the modern pharmaceutical industry was born from botanical medicine, synthetic approaches to drug discovery have become standard. However, this modern approach has led to a decline in new drug development in recent years and a growing market for botanical therapeutics that are currently available as dietary supplements, drugs, or botanical drugs. Most botanical therapeutics are derived from medicinal plants that have been cultivated for increased yields of bioactive components. The phytochemical composition of many plants has changed over time, with domestication of agricultural crops resulting in the enhanced content of some bioactive compounds and diminished content of others. Plants continue to serve as a valuable source of therapeutic compounds because of their vast biosynthetic capacity. A primary advantage of botanicals is their complex composition consisting of collections of related compounds having multiple activities that interact for a greater total activity.

Two new constituents from Artemisia capillaris Thunb

Two new compounds, 6'-O-caffeoyl-p-hydroxyacetophenone-4-O-beta-D-glucopyranoside(1) and 6-amino-9-[1-(3,4-dihydroxyphenyl)ethyl]-9H-purine (2) were isolated from the aerial parts of Artemisia capillaris Thunb. The structures were established on the basis of spectral data.

Evaluation of botanicals for improving human health

Botanical preparations have been used medicinally for thousands of years. Many commercially available botanical products are being marketed in the United States with little or no publicly available scientific validation of efficacy or consistency. For botanicals to be reliable for research purposes and consumer products, they must be standardized with sufficient quality controls to ensure consistent composition, safety, and potency. This includes uniform cultivation of source plants with controls to monitor for contamination from other species, pesticides, and environmental toxins. The active components of botanicals must be identified by activity-guided fractionation with the use of in vitro assays that require little test material followed by validation in vivo. Concentrations of active compounds within the botanicals can then be accurately measured to ensure the delivery of a dependable dose in the final product. The use of bioenhancing agents may be considered for compounds with poor bioavailability. Standardization of botanical therapeutics can only be achieved when the active compounds are identified and biological activity is confirmed, thus ensuring a consistent product.

Polyphenolic compounds from Artemisia dracunculus L. inhibit PEPCK gene expression and gluconeogenesis in an H4IIE hepatoma cell line

An ethanolic extract of Russian tarragon, Artemisia dracunculus L., with antihyperglycemic activity in animal models was reported to decrease phosphoenolpyruvate carboxykinase (PEPCK) mRNA expression in STZ-induced diabetic rats. A quantitative polymerase chain reaction (qPCR) assay was developed for the bioactivity-guided purification of the compounds within the extract that decrease PEPCK expression. The assay was based on the inhibition of dexamethasone-stimulated PEPCK upregulation in an H4IIE hepatoma cell line. Two polyphenolic compounds that inhibited PEPCK mRNA levels were isolated and identified as 6-demethoxycapillarisin and 2',4'-dihydroxy-4-methoxydihydrochalcone with IC(50) values of 43 and 61 muM, respectively. The phosphoinositide-3 kinase (PI3K) inhibitor LY-294002 showed that 6-demethoxycapillarisin exerts its effect through the activation of the PI3K pathway, similarly to insulin. The effect of 2',4'-dihydroxy-4-methoxydihydrochalcone is not regulated by PI3K and dependent on activation of AMPK pathway. These results indicate that the isolated compounds may be responsible for much of the glucose-lowering activity of the Artemisia dracunculus extract.

Revisiting the ancient concept of botanical therapeutics

Mixtures of interacting compounds produced by plants may provide important combination therapies that simultaneously affect multiple pharmacological targets and provide clinical efficacy beyond the reach of single compound-based drugs. Developing innovative scientific methods for discovery, validation, characterization and standardization of these multicomponent botanical therapeutics is essential to their acceptance into mainstream medicine.