Showing papers in "Planta Medica in 2014"

Preclinical Evidence for the Pharmacological Actions of Naringin: A Review

Abstract: Naringin, chemically 4′,5,7- trihydroxyflavanone-7-rhamnoglucoside, is a major flavanone glycoside obtained from tomatoes, grapefruits, and many other citrus fruits. It has been experimentally documented to possess numerous biological properties such as antioxidant, anti-inflammatory, and antiapoptotic activities. In vitro and in vivo studies have further established the usefulness of naringin in various preclinical models of atherosclerosis, cardiovascular disorders, diabetes mellitus, neurodegenerative disorders, osteoporosis, and rheumatological disorders. Apart from this, naringin has also exerted chemopreventive and anticancer attributes in various models of oral, breast, colon, liver, lung, and ovarian cancer. This wide spectrum of biological expediency has been documented to be a result of either the upregulation of various cell survival proteins or the inhibition of inflammatory processes, or a combination of both. Due to the scarcity of human studies on naringin, this review focuses on the various established activities of naringin in in vitro and in vivo preclinical models, and its potential therapeutic applications using the available knowledge in the literature. Additionally, it also encompasses the pharmacokinetic properties of naringin and its inhibition of CYP isoenzymes, and the subsequent drug interactions. Moreover, further clinical research is evidently needed to provide significant insights into the mechanisms underlying the effects of naringin in humans.

Kaempferol derivatives as antiviral drugs against the 3a channel protein of coronavirus.

Abstract: The protein coded by the open-reading-frame 3a of SARS coronavirus has been demonstrated to form a cation-selective channel that may become expressed in the infected cell. The activity of the channel is involved in the mechanism of virus release. Drugs that inhibit the ion channel can, therefore, inhibit virus release, and they could be a source for development of novel therapeutic antiviral agents. Various drugs found in Chinese herbs that are well known as anticancer agents also have an antiviral potency. Here we tested the flavonols kaempferol, kaempferol glycosides, and acylated kaempferol glucoside derivatives with respect to their potency to block the 3a channel. We used the Xenopus oocyte with a heterologously expressed 3a protein as a model system to test the efficacy of the flavonols. Some of these drugs turned out to be potent inhibitors of the 3a channel. The most effective one was the glycoside juglanin (carrying an arabinose residue) with an IC50 value of 2.3 µM for inhibition of the 3a-mediated current. Kaempferol derivatives with rhamnose residue also seem to be quite effective. We suggest that viral ion channels, in general, may be a good target for the development of antiviral agents, and that, in particular, kaempferol glycosides are good candidates for 3a channel proteins of coronaviruses.

Exploring marine resources for bioactive compounds.

Abstract: 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.

Naturally occurring homoisoflavonoids and their pharmacological activities.

Abstract: Homoisoflavonoids, a special subclass of flavonoids, are rarely found in nature, mainly existing in Fabaceae and Asparagaceae families and being less common in Polygonaceae, Portulacaceae, Orchidaceae, and Gentianaceae families. Until now, approximately 240 natural occurring homoisoflavonoids have been identified from roots, barks, heartwood, bulbs, leaves, and seeds of the plants from the above mentioned families, which have often been used in traditional medicine. Homoisoflavonoids have been reported with a broad range of bioactivities, including anti-microbial, anti-mutagenic, anti-oxidant, immunomodulatory, anti-diabetic, cytotoxic, anti-angiogenic, vasorelaxant, and anti-inflammatory effects. To organize this review, the homoisoflavonoids were classified into five groups based on their structures: sappanin-type (I), scillascillin-type (II), brazilin-type (III), caesalpin-type (IV), and protosappanin-type (V). The structures of natural occurring homoisoflavonoids are described, and their proposed biosynthetic pathway and recent pharmacological studies are discussed. The main purpose of this review is to provide a comprehensive and up-to-date state of knowledge from phytochemical and pharmacological studies performed on homoisoflavonoids during the past decades. Homoisoflavonoids might have a large potential for further investigations of their bioactivities in order to identify important leads.

Hydrogen Sulfide Releasing Capacity of Natural Isothiocyanates: Is It a Reliable Explanation for the Multiple Biological Effects of Brassicaceae?

Abstract: Hydrogen sulfide is an endogenous pleiotropic gasotransmitter, which mediates important physiological effects in the human body. Accordingly, an impaired production of endogenous hydrogen sulfide contributes to the pathogenesis of important disorders. To date, exogenous compounds, acting as hydrogen sulfide-releasing agents, are viewed as promising pharmacotherapeutic agents. In a recent report, the hydrogen sulfide-releasing properties of some synthetic aryl isothiocyanate derivatives have been reported, indicating that the isothiocyanate function can be viewed as a suitable slow hydrogen sulfide-releasing moiety, endowed with the pharmacological potential typical of this gasotransmitter. Many isothiocyanate derivatives (deriving from a myrosinase-mediated transformation of glucosinolates) are well-known secondary metabolites of plants belonging to the family Brassicaceae, a large botanical family comprising many edible species. The phytotherapeutic and nutraceutic usefulness of Brassicaceae in the prevention of important human diseases, such as cancer, neurodegenerative processes and cardiovascular diseases has been widely discussed in the scientific literature. Although these effects have been largely attributed to isothiocyanates, the exact mechanism of action is still unknown. In this experimental work, we aimed to investigate the possible hydrogen sulfide-releasing capacity of some important natural isothiocyanates, studying it in vitro by amperometric detection. Some of the tested natural isothiocyanates exhibited significant hydrogen sulfide release, leading us to hypothesize that hydrogen sulfide may be, at least in part, a relevant player accounting for several biological effects of Brassicaceae.

Mechanisms of action of phytochemicals from medicinal herbs in the treatment of Alzheimer's disease

Abstract: !Alzheimerʼs disease is a chronic neurodegenerative disorder characterized by progressive dementia and deterioration of cognitive function. Although several drugs currently used for the treatment of Alzheimerʼs 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 Alzheimerʼs 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. !

African Medicinal Plants with Antidiabetic Potentials: A Review

Abstract: Diabetes mellitus is one of the major health prob- lems in Africa. The conventional oral synthetic antidiabetic drugs available to manage the dis- ease are costly and not readily affordable to the majority of the affected population. Interestingly, the continent is endowed with a tremendous number of medicinal plants that have been ex- plored for their folkloric treatment of diabetes mellitus. Scientific investigations have validated the antidiabetic potentials of a number of these medicinal plants but there is no repository with information on these scientifically investigated plants as a guide for future research. In this re- view article, all of the in vivo antidiabetic studies

Evaluation of In Vitro Absorption, Distribution, Metabolism, and Excretion (ADME) Properties of Mitragynine, 7-Hydroxymitragynine, and Mitraphylline

Abstract: Mitragyna speciosa (kratom) is a popular herb in Southeast Asia, which is traditionally used to treat withdrawal symptoms associated with opiate addiction. Mitragynine, 7-hydroxymitragynine, and mitraphylline are reported to be the central nervous system active alkaloids which bind to the opiate receptors. Mitraphylline is also present in the bark of Uncaria tomentosa (catʼs claw). Several therapeutic properties have been reported for these compounds but limited information is available on the absorption and distribution properties. This study focuses on evaluating the absorption, distribution, metabolism, and excretion (ADME) properties of these compounds and their effect on major efflux transporter P-glycoprotein, using in vitro methods. Quantitative analysis was performed by the Q-TOF LC-MS system. Mitragynine was unstable in simulated gastric fluid with 26 % degradation but stable in simulated intestinal fluid. 7-Hydroxymitragynine degraded up to 27 % in simulated gastric fluid, which could account for its conversion to mitragynine (23 %), while only 6 % degradation was seen in simulated intestinal fluid. Mitraphylline was stable in simulated gastric fluid but unstable in simulated intestinal fluid (13.6 % degradation). Mitragynine and 7-hydroxymitragynine showed moderate permeability across Caco-2 and MDR-MDCK monolayers with no significant efflux. However, mitraphylline was subjected to efflux mediated by P-glycoprotein in both Caco-2 and MDR-MDCK monolayers. Mitragynine was found to be metabolically stable in both human liver microsomes and S9 fractions. In contrast, both 7-hydroxymitragynine and mitraphylline were metabolized by human liver microsomes with half-lives of 24 and 50 min, respectively. All three compounds exhibited high plasma protein binding (> 90 %) determined by equilibrium dialysis. Mitragynine and 7-hydroxymitragynine inhibited P-glycoprotein with EC50 values of 18.2 ± 3.6 µM and 32.4 ± 1.9 µM, respectively, determined by the calcein-AM fluorescent assay, while no inhibition was seen with mitraphylline. These data indicate the possibility of a drug interaction if mitragynine and 7-hydroxymitragynine are coadministered with drugs that are P-glycoprotein substrates.

Influence of Gut Microbiota-Derived Ellagitanninsʼ Metabolites Urolithins on Pro-Inflammatory Activities of Human Neutrophils

Abstract: Ellagitannin-rich products exhibit beneficial influence in the case of inflammation-associated diseases. Urolithins, metabolites of ellagitannins produced by gut microbiota, in contrary to high molecular weight hydrophilic parental polyphenols, possess well established bioavailability. Because of the important role of neutrophils in progression of inflammation, the influence of urolithins on their pro-inflammatory functions was tested. Urolithin B at a concentration of 20 µM showed significant inhibition of interleukin 8 and extracellular matrix-degrading enzyme MMP-9 production. It was also significantly active in prevention of cytochalasin A/formyl-met-leu-phenylalanine-triggered selectin CD62L shedding. Urolithin C was the only active compound towards inhibition of elastase release from cytochalasin A/formyl-met-leu-phenylalanine-stimulated neutrophils with 39.0 ± 15.9 % inhibition at a concentration of 5 µM. Myeloperoxidase release was inhibited by urolithins A and C (at 20 µM by 46.7 ± 16.1 and 63.8 ± 8.6 %, respectively). Urolithin A was the most potent reactive oxygen species release inhibitor both in formyl-met-leu-phenylalanine and 4β-phorbol-12β-myristate-R13-acetate-stimulated neutrophils. At the concentration of 1 µM, it caused reactive oxygen species level decrease by 42.6 ± 26.6 and 53.7 ± 16.0 %, respectively. Urolithins can specifically modulate inflammatory functions of neutrophils, and thus could contribute to the beneficial health effects of ellagitannin-rich medicinal plant materials and food products.

Antimicrobial, antioxidative, and insect repellent effects of Artemisia absinthium essential oil.

Abstract: In this paper, the chemical composition and biological activity of the essential oil of Artemisia absinthium was studied. The aim of this study was to investigate the potential of ethnopharmacological uses of this plant species in the treatment of gastrointestinal diseases and wounds, and as an insect repellent. The aerial part of the plant was hydrodistilled, and the chemical composition of the essential oil was analyzed by gas chromatography and gas chromatography/mass spectrometry. Forty-seven compounds, corresponding to 94.65 % of the total oil, were identified, with the main constituents being sabinene (24.49 %), sabinyl acetate (13.64 %), and α-phellandrene (10.29 %). The oil yield was 0.23 % (v/w). The antimicrobial activity of the oil was investigated against ten bacterial isolates (from patients wounds and stools) and seven American Type Culture Collection strains using a microwell dilution assay. The minimal inhibitory/bactericidal concentration of the oil ranged from < 0.08 to 2.43 mg/mL and from 0.08 to 38.80 mg/mL, respectively. The antioxidant activity of the essential oil was evaluated using 2,2-diphenyl-1-picrylhydrazil and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical-scavenging methods and assessed as significant. Skin irritation potential and acute toxicity of the oil were also investigated. Results of the skin irritant reaction showed that none of the 30 volunteers developed a positive skin irritant reaction to undiluted A. absinthium essential oil. Acute oral exposure to the essential oil did not cause mortality in the treated mice, but it did cause neurological, muscle, and gastrointestinal problems. A subchronic toxicity test on Drosophila melanogaster showed that the essential oil of A. absinthium is toxic for developing insect larvae. Starting with the concentration of 0.38 % of essential oil in medium, significant mortality of larvae exposed to the oil was noted when compared to the control. Probit analysis revealed that the LC50 value of A. absinthium essential oil for D. melanogaster larvae after 15 days of exposure was 6.31 % (49 mg/mL). The essential oil also affected the development of D. melanogaster larvae and significantly delayed achievement of the pupa stadium.

Olive leaf extracts protect cardiomyocytes against 4-hydroxynonenal-induced toxicity in vitro: comparison with oleuropein, hydroxytyrosol, and quercetin.

Abstract: Olive (Olea europaea) leaf, an important traditional herbal medicine, displays cardioprotection that may be related to the cellular redox modulating effects of its polyphenolic constituents. This study was undertaken to investigate the protective effect of the ethanolic and methanolic extracts of olive leaves compared to the effects of oleuropein, hydroxytyrosol, and quercetin as a positive standard in a carbonyl compound (4-hydroxynonenal)-induced model of oxidative damage to rat cardiomyocytes (H9c2). Cell viability was detected by the MTT assay; reactive oxygen species production was assessed by the 2′,7′-dichlorodihydrofluorescein diacetate method, and the mitochondrial membrane potential was determined using a JC-1 dye kit. Phospho-Hsp27 (Ser82), phospho-MAPKAPK-2 (Thr334), phospho-c-Jun (Ser73), cleaved-caspase-3 (cl-CASP3) (Asp175), and phospho-SAPK/JNK (Thr183/Tyr185) were measured by Western blotting. The ethanolic and methanolic extracts of olive leaves inhibited 4-hydroxynonenal-induced apoptosis, characterized by increased reactive oxygen species production, impaired viability (LD50: 25 µM), mitochondrial dysfunction, and activation of pro-apoptotic cl-CASP3. The ethanolic and methanolic extracts of olive leaves also inhibited 4-hydroxynonenal-induced phosphorylation of stress-activated transcription factors, and the effects of extracts on p-SAPK/JNK, p-Hsp27, and p-MAPKAPK-2 were found to be concentration-dependent and comparable with oleuropein, hydroxytyrosol, and quercetin. While the methanolic extract downregulated 4-hydroxynonenal-induced p-MAPKAPK-2 and p-c-Jun more than the ethanolic extract, it exerted a less inhibitory effect than the ethanolic extract on 4-hydroxynonenal-induced p-SAPK/JNK and p-Hsp27. cl-CASP3 and p-Hsp27 were attenuated, especially by quercetin. Experiments showed a predominant reactive oxygen species inhibitory and mitochondrial protecting ability at a concentration of 1–10 µg/mL of each extract, oleuropein, hydroxytyrosol, and quercetin. The ethanolic extract of olive leaves, which contains larger amounts of oleuropein, hydroxytyrosol, verbascoside, luteolin, and quercetin (by HPLC) than the methanolic one, has more protecting ability on cardiomyocyte viability than the methanolic extract or each phenolic compound against 4-hydroxynonenal-induced carbonyl stress and toxicity.

Methods Applied to the In Vitro Primary Toxicology Testing of Natural Products: State of the Art, Strengths, and Limits

Abstract: The present review attempts to build up a comprehensive picture of the major primary techniques used to screen and assess the cytotoxicity of plant complex mixtures. These can be based on metabolic activity, on membrane integrity, on morphological features, on cell growth; the type of cell death can also be established from more or less specific events (e.g., apoptosis, autophagy, DNA damage detection, reactive oxygen species involvement). This review will discuss the benefits, the difficulties, and the challenges that may occur along cytotoxicity testing of raw extracts and isolated natural compounds.

Protective role of Cupressuflavone from Cupressus macrocarpa against carbon tetrachloride-induced hepato- and nephrotoxicity in mice.

Abstract: The hepatoprotective and nephroprotective activity of cupressuflavone isolated from Cupressus macrocarpa was investigated against CCl4-induced toxicity in mice. Cupressuflavone was administered (40, 80, and 160 mg/kg/day) for five days. CCl4 was administered (0.5 mL/kg intraperitoneally) at the end of the experiment. A substantial increase (p < 0.001) in the levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, total bilirubin, cholesterol, creatinine, uric acid, urea, and malondialdehyde was observed in the CCl4-treated group compared to the normal control group. In contrast, a significant reduction (p < 0.001) in glutathione and superoxide dismutase contents as well as the total protein level was evident in the CCl4-intoxicated mice. Cupressuflavone pretreatment markedly inhibited the CCl4-induced increase in alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, cholesterol, creatinine, uric acid, urea, and malondialdehyde levels in a dose-dependent manner (p < 0.001 at all the tested doses). In addition, a significant (p

Simultaneous determination of five minor coumarins and flavonoids in Glycyrrhiza uralensis by solid-phase extraction and high-performance liquid chromatography/electrospray ionization tandem mass spectrometry.

Abstract: Minor phenolic compounds in licorice (Glycyrrhiza uralensis) have recently been proved for diverse bioactivities and favorable bioavailability, indicating that they may play an important role in the therapeutic effects or herb-drug interactions of licorice. However, so far, their abundance in licorice remains unknown. In this study, a reliable solid-phase extraction coupled with a high-performance liquid chromatography and diode array detection method was established to determine the minor phenolic compounds in licorice. The analytes were enriched by a three-step solid-phase extraction method, and then separated on a YMC ODS-A column by gradient elution. Five coumarins and flavonoids were identified by electrospray ionization tandem mass spectrometry, and then quantified using high-performance liquid chromatography and diode array detection. The amounts of glycycoumarin, dehydroglyasperin C, glycyrol, licoflavonol, and glycyrin in G. uralensis were 0.81 ± 0.28, 1.25 ± 0.59, 0.20 ± 0.08, 0.12 ± 0.04, and 0.17 ± 0.08 mg/g, respectively. Abundances of these compounds in other Glycyrrhiza species (G. glabra, G. inflata, and G. yunnanesis) were remarkably lower than G. uralensis.

Combined use of extract libraries and HPLC-based activity profiling for lead discovery: potential, challenges, and practical considerations.

Abstract: A 96-well format plant extract library and a tailored technology platform have been set up for the discovery of new natural product lead compounds. The considerable advantages of the library approach are discussed. Key considerations such as sample generation, logistics, and data management are addressed. The potential of a HPLC-based profiling approach combining off-line bioassays with in-line and off-line spectroscopy (including HR-ESIMS and microprobe NMR) for tracking bioactivity is demonstrated with a selection of examples encompassing different types of bioassay formats. The information generated by this approach with regards to hit prioritization and preliminary structure activity-relationships is discussed. Practical aspects, such as validation of profiling protocols, the amounts of extracts to be applied, and the re-dissolution of fractions are addressed. Such information is intended for scientists aiming at implementing library-based discovery platforms in their own laboratory.

In vitro anti-inflammatory and wound-healing potential of a Phyllostachys edulis leaf extract--identification of isoorientin as an active compound.

Abstract: Extracts prepared from the leaves of Phyllostachys edulis (bamboo) have received attention in pharmacological research due to their potent antitumor, anti-inflammatory, antimicrobial, and anti-ulcerogenic activities. In this study, anti-inflammatory effects of a bamboo leaf extract on tumor necrosis factor alpha-induced overproduction of interleukin 8, vascular endothelial growth factor, and interleukin 6 in immortalized human keratinocytes were investigated for the first time. In addition, wound-healing effects were evaluated in 3T3-swiss albino mouse fibroblasts. Bamboo leaf extract and isoorientin inhibited the tumor necrosis factor alpha-induced release of interleukin 8 and vascular endothelial growth factor. Furthermore, isoorientin dose-dependently reduced levels of interleukin 6 in tumor necrosis factor alpha-α-treated immortalized human keratinocytes cells. Wound healing was evaluated using a modification of the classical scratch assay. For evaluation of the wound gap, a new computerized method based on time-lapse microscopy was developed. It was shown that bamboo leaf extract (10 µg/mL) improved wound closure by 28 % (12 h) and 54 % (24 h), respectively. In concentrations of 50 µg/mL and above, bamboo leaf extract inhibited cell migration without affecting cell viability. Isoorientin (10 µM) improved wound closure by 29 % (12 h) and 56 % (24 h), respectively. Comparable to bamboo leaf extract, higher concentrations of isoorientin prevented cell migration. It is suggested that bamboo leaf extract as well as isoorientin have a dual activity – in higher doses, they show anti-inflammatory effects, and in lower concentrations, they exert anti-angiogenic activities.

Genistein as antiviral drug against HIV ion channel.

Abstract: Various drugs found in Chinese herbs are well known for their antiviral potency. We have tested several flavonoids with respect to their potency to block the viral protein U of the human immunodeficiency type 1 virus, which is believed to form a cation-permeable ion channel in the infected cell. We used Xenopus oocytes with heterologously expressed viral protein U as model system to test the efficacy of the drugs in voltage-clamp experiments. This method had been demonstrated in the past as a useful tool to screen drugs for their potency in inhibition of ion channel activity. The viral protein U-mediated current could be inhibited by Ba(2+) with a K1/2 value of 1.6 mM. Therefore, we determined viral protein U-mediated current as current component blocked by 10 mM Ba(2+). We screened several flavonoids with respect to their effects on this current. The flavonols quercetin and kaempferol, and the flavanols (-)epigallochatechin and (-)epichatechin were ineffective. The flavanone naringenin showed at 20 µM slight (about 10%) inhibition. The most potent drug was the isoflavon genistein which exhibited at 20 µM significant inhibition of about 40% with a K1/2 value of 81 ± 4 µM. We suggest that viral ion channels, in general, may be a good target for development of antiviral agents, and that, in particular, isoflavons may be candidates for development of drugs targeting viral protein U.

Enhancement of voltage-gated K+ channels and depression of voltage-gated Ca2+ channels are involved in quercetin-induced vasorelaxation in rat coronary artery.

Abstract: Quercetin is one of the most common flavonoids in the human daily diet. Its affects the coronary artery, especially L-type voltage-gated Ca 2+ channels and voltage-gated K + channels in the arterial smooth muscle cells, which are poorly understood. The present experiments were designed to study the myogenic effect of quercetin and its possible underlying mechanisms in the rat coronary artery. A wire myograph was used to observe the myogenic effects. Arterial smooth muscle cells were freshly isolated from the rat coronary artery and the intracellular free Ca 2+ concentration was measured with molecular probe fluo-4-AM. The effects of quercetin on L-type voltage-gated Ca 2+ channels and voltage-gated K + channels were studied using a whole-cell patch clamp. Quercetin (3–30 µM) produced a depression and relaxation on the contraction induced by KCl or the thromboxane A2 analog 9,11-Dideoxy-9 α ,11 α -methanoepoxy prostaglandin F 2α . The vasorelaxation was attenuated by 4-aminopyridine, a specific voltage-gated K + channel inhibitor, but was not affected by the NG-nitro-L-arginine methylester ester (a nitric oxide synthesis inhibitor), glibenclamide (a ATP-activated K + channel inhibitor), iberiotoxin (a Ca 2+ -activated K + channel inhibitor), BaCl 2 (an inward rectifier K + channel inhibitor), or by endothelium denudation. At the same concentrations, quercetin reduced the KCl-induced elevation of the intracellular free Ca 2+ concentration, inhibited the inward Ca 2+ currents through L-type voltage-gated Ca 2+ channels, and increased the outward K + currents through voltage-gated K + channels in the rat coronary artery smooth muscle cells. Collectively, our results demonstrate that quercetin possesses vasospasmolytic effects in RCA and suggest that depression of the Ca 2+ influx through L-type voltage-gated Ca 2+ channels and augmentation of voltage-gated K + channel activity in the myocytes may underlie coronary relaxation.

The inhibitory effect of Scutellaria baicalensis extract and its active compound, baicalin, on the translocation of the androgen receptor with implications for preventing androgenetic alopecia.

Abstract: Androgens affect several human skin and prostate functions, and the androgen receptor is crucial for regulating the androgen-related mechanisms. In this study, we assessed the antagonizing effects of a Scutellaria baicalensis extract and its main component baicalin on proliferation of human scalp dermal papilla cells. First, the extract and baicalin slightly dissociated the radioisotope-labeled androgen receptor-agonist complex in the androgen receptor binding assay, and the IC 50 values were measured to assess the androgen receptor antagonistic effect of the extract (93 µg/mL) and baicalin (54.1 µM). Second, the extract and baicalin treatments dose-dependently inhibited the overgrowth of LNCaP prostate cancer cells, which were stimulated by dihydrotestosterone. Third, the extract and baicalin inhibited nuclear translocation of the androgen receptor stimulated by dihydrotestosterone in human dermal papilla cells. Additionally, the extract and baicalin enhanced proliferation of human dermal papilla cells in vitro . These results show that the extract and baicalin inhibited androgen activation signaling and promoted hDPC proliferation, suggesting that they could be used as active ingredients for treating androgen-associated disorders, such as androgenetic alopecia.

In vitro antiprotozoal and cytotoxic activity of ethnopharmacologically selected guinean plants.

Abstract: Based on an ethnobotanical survey, 41 Guinean plant species widely used in the traditional treatment of fever and/or malaria were collected. From these, 74 polar and apolar extracts were prepared and tested for their in vitro antiprotozoal activity along with their cytotoxicity on MRC-5 cells. A potent activity (IC50 < 5 µg/mL) was observed for Terminalia albida, Vismia guineensis, Spondias mombin, and Pavetta crassipes against Plasmodium falciparum; for Pavetta crassipes, Vismia guineensis, Guiera senegalensis, Spondias mombin, Terminalia macroptera, and Combretum glutinosum against Trypanosoma brucei brucei; for Bridelia ferruginea, G. senegalensis, V. guineensis, P. crassipes, and C. glutinosum against Trypanosoma cruzi. Only the extract of Tetracera alnifolia showed a good activity (IC50 8.1 µg/mL) against Leishmania infantum. The selectivity index of the active samples varied from 0.08 to > 100. These results may validate at least in part the traditional use of some of the plant species.

Identification and characterization of anticancer compounds targeting apoptosis and autophagy from Chinese native Garcinia species.

Abstract: Natural compounds from medicinal plants are important resources for drug development. Active compounds targeting apoptosis and autophagy are candidates for anti-cancer drugs. In this study, we collected Garcinia species from China and extracted them into water or ethanol fractions. Then, we performed a functional screen in search of novel apoptosis and autophagy regulators. We first characterized the anti-proliferation activity of the crude extracts on multiple cell lines. HeLa cells expressing GFP-LC3 were used to examine the effects of the crude extracts on autophagy. Their activities were confirmed by Western blots of A549 and HeLa cells. By using bioassay guided fractionation, we found that two caged prenylxanthones from Garcinia bracteata, neobractatin and isobractatin, can significantly induce apoptosis and inhibit autophagy. Our results suggest that different Garcinia species displayed various degrees of toxicity on different cancer cell lines. Furthermore, the use of a high content screening assay to screen natural products was an essential method to identify novel autophagy regulators.

Sucrose Esters from Physalis peruviana Calyces with Anti-Inflammatory Activity

Abstract: Physalis peruviana is a native plant from the South American Andes and is widely used in traditional Colombian medicine of as an anti-inflammatory medicinal plant, specifically the leaves, calyces, and small stems in poultice form. Previous studies performed by our group on P. peruviana calyces showed potent anti-inflammatory activity in an enriched fraction obtained from an ether total extract. The objective of the present study was to obtain and elucidate the active compounds from this fraction and evaluate their anti-inflammatory activity in vivo and in vitro. The enriched fraction of P. peruviana was purified by several chromatographic methods to obtain an inseparable mixture of two new sucrose esters named peruviose A (1) and peruviose B (2). Structures of the new compounds were elucidated using spectroscopic methods and chemical transformations. The anti-inflammatory activity of the peruvioses mixture was evaluated using λ-carrageenan-induced paw edema in rats and lipopolysaccharide-activated peritoneal macrophages. Results showed that the peruvioses did not produce side effects on the liver and kidneys and significantly attenuated the inflammation induced by λ-carrageenan in a dosage-dependent manner, probably due to an inhibition of nitric oxide and prostaglandin E2, which was demonstrated in vitro. To our knowledge, this is the first report of the presence of sucrose esters in P. peruviana that showed a potent anti-inflammatory effect. These results suggest the potential of sucrose esters from the Physalis genus as a novel natural alternative to treat inflammatory diseases.

In vitro and in vivo evaluation of the effect of puerarin on hepatic cytochrome p450-mediated drug metabolism.

Abstract: Puerarin (8-β-D-glucopyranosyl-7-hydroxy-3-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) is a major pharmacological component of Puerariae Radix, the root of Pueraria lobata. We investigated the effect of puerarin on hepatic cytochrome P450-mediated drug metabolism in rats and humans. The in vitro cytochrome P450 inhibitory effect of puerarin in human and rat liver microsomes was evaluated using the following model cytochrome P450 substrates: phenacetin for CYP1A, diclofenac for CYP2C, dextromethorphan for CYP2D, and testosterone for CYP3A. The in vivo pharmacokinetics of intravenous and oral buspirone, a probe substrate for CYP3A, was studied with single simultaneous intravenous coadministration of puerarin in rats. In the in vitro cytochrome P450 inhibition study, the rate of disappearance of testosterone was significantly reduced in the presence of 10 µM PU, while that of other cytochrome P450 substrates was not significantly affected in both human and rat liver microsomes, suggesting that puerarin inhibits the in vitro hepatic CYP3A-mediated metabolism in the human and rat systems (IC50 = 15.5 ± 3.9 µM). After intravenous administration of buspirone with single simultaneous coadministration of intravenous puerarin at a dose of 10 mg/kg in rats, the total area under the plasma concentration–time curve from time zero to time infinity was increased while time-averaged total body clearance decreased. When buspirone was orally administered in rats with the 10 mg/kg intravenous puerarin coadministration, both total area under the plasma concentration–time curve from time zero to time infinity and the extent of absolute oral bioavailability were significantly increased. Therefore, results of the in vitro microsomal and in vivo pharmacokinetic studies suggest the possible inhibition of hepatic CYP3A-mediated drug metabolism by puerarin administration, potentially leading to metabolism-mediated herb–drug interactions with clinical significance.

Inhibition of Tau Aggregation by Three Aspergillus nidulans Secondary Metabolites: 2,ω-Dihydroxyemodin, Asperthecin, and Asperbenzaldehyde

Abstract: The aggregation of the microtubule-associated protein tau is a significant event in many neurodegenerative diseases including Alzheimerʼs disease. The inhibition or reversal of tau aggregation is therefore a potential therapeutic strategy for these diseases. Fungal natural products have proven to be a rich source of useful compounds having wide varieties of biological activity. We have screened Aspergillus nidulans secondary metabolites containing aromatic ring structures for their ability to inhibit tau aggregation in vitro using an arachidonic acid polymerization protocol and the previously identified aggregation inhibitor emodin as a positive control. While several compounds showed some activity, 2,ω-dihydroxyemodin, asperthecin, and asperbenzaldehyde were potent aggregation inhibitors as determined by both a filter trap assay and electron microscopy. In this study, these three compounds were stronger inhibitors than emodin, which has been shown in a prior study to inhibit the heparin induction of tau aggregation with an IC50 of 1–5 µM. Additionally, 2,ω-dihydroxyemodin, asperthecin, and asperbenzaldehyde reduced, but did not block, tau stabilization of microtubules. 2,ω-Dihydroxyemodin and asperthecin have similar structures to previously identified tau aggregation inhibitors, while asperbenzaldehyde represents a new class of compounds with tau aggregation inhibitor activity. Asperbenzaldehyde can be readily modified into compounds with strong lipoxygenase inhibitor activity, suggesting that compounds derived from asperbenzaldehyde could have dual activity. Together, our data demonstrates the potential of 2,ω-dihydroxyemodin, asperthecin, and asperbenzaldehyde as lead compounds for further development as therapeutics to inhibit tau aggregation in Alzheimerʼs disease and neurodegenerative tauopathies.

In vitro and in vivo antiplasmodial activity of three Rwandan medicinal plants and identification of their active compounds.

Abstract: In our previous study, we reported the interesting in vitro antiplasmodial activity of some Rwandan plant extracts. This gave rise to the need for these extracts to also be evaluated in vivo and to identify the compounds responsible for their antiplasmodial activity. The aim of our study was, on the one hand, to evaluate the antiplasmodial activity in vivo and the safety of the selected Rwandan medicinal plants used in the treatment of malaria, with the objective of promoting the development of improved traditional medicines and, on the other hand, to identify the active ingredients in the plants. Plant extracts were selected according to their selectivity index. The in vivo antiplasmodial activity of aqueous, methanolic, and dichloromethane extracts was then evaluated using the classical 4-day suppressive test on Plasmodium berghei infected mice. The activity of the plant extracts was estimated by measuring the percentage of parasitemia reduction, and the survival of the experimental animals was recorded. A bioguided fractionation was performed for the most promising plants, in terms of antiplasmodial activity, in order to isolate active compounds identified by means of spectroscopic and spectrometric methods. The highest level of antiplasmodial activity was observed with the methanolic extract of Fuerstia africana (> 70 %) on days 4 and 7 post-treatment after intraperitoneal injection and on day 7 using oral administration. After oral administration, the level of parasitemia reduction observed on day 4 post-infection was 44 % and 37 % with the aqueous extract of Terminalia mollis and Zanthoxylum chalybeum , respectively. However, the Z. chalybeum extract presented a high level of toxicity after intraperitoneal injection, with no animals surviving on day 1 post-treatment. F. africana , on the other hand, was safer with 40 % mouse survival on day 20 post-treatment. Ferruginol is already known as the active ingredient in F. Africana , and ellagic acid (IC 50 = 175 ng/mL) and nitidine (IC 50 = 77.5 ng/mL) were identified as the main active constituents of T. mollis and Z. chalybeum , respectively. F. africana presented very promising antiplasmodial activity in vivo . Although most of the plants tested showed some level of antiplasmodial activity, some of these plants may be toxic. This study revealed for the first time the role of ellagic acid and nitidine as the main antimalarial compounds in T. mollis and Z. chalybeum , respectively.

Vermistatin derivatives with α-glucosidase inhibitory activity from the mangrove endophytic fungus Penicillium sp. HN29-3B1.

Abstract: Three new vermistatin derivatives, 6-demethylpenisimplicissin (1), 5′-hydroxypenisimplicissin (2), and 2′′-epihydroxydihydrovermistatin (3), along with five known vermistatin analogues, methoxyvermistatin (4), vermistatin (5), 6-demethylvermistatin (6), hydroxyvermistatin (7), and penisimplicissin (8), were isolated from the culture of the mangrove endophytic fungus Penicillium sp. HN29-3B1 from Cerbera manghas. Their structures were elucidated mainly by nuclear magnetic resonance spectroscopy. The absolute configurations of compounds 1 and 2 were deduced on the basis of circular dichroism data. The absolute structures of compounds 3 and 5 were confirmed by a single-crystal X-ray diffraction experiment using Cu Kα radiation. In the bioactivity assay, compounds 1 and 3 exhibited α-glucosidase inhibitory activity with IC50 values of 9.5 ± 1.2 and 8.0 ± 1.5 µM, respectively. The plausible biosynthetic pathways for all compounds are discussed.

Quercetin, luteolin, and epigallocatechin gallate promote glucose disposal in adipocytes with regulation of AMP-activated kinase and/or sirtuin 1 activity.

Abstract: Quercetin, luteolin, and epigallocatechin gallate are flavonoids abundant in edible and medicinal plants with beneficial effects on glucose homeostasis. This study explored the action of these flavonoids on glucose disposal in adipocytes. Quercetin, luteolin, and epigallocatechin gallate enhanced glucose consumption with the positive regulation of AMP-activated kinase phosphorylation, and the AMP-activated kinase inhibitor compound C abolished their effects on glucose consumption. Luteolin and epigallocatechin gallate, but not quercetin, increased sirtuin 1 abundance, and their regulation of glucose consumption was also attenuated by co-treatment with sirtuin 1 inhibitor nicotinamide. Quercetin, luteolin, and epigallocatechin gallate suppressed nuclear factor-κB activation by inhibition of p65 phosphorylation with beneficial regulation of adipokine expression, whereas these actions were diminished by coincubation with compound C. The sirtuin 1 inhibitor nicotinamide attenuated the effects of luteolin and EGCG on p65 phosphorylation and adipokine expression without any influence on the activity of quercetin. Results of Western blot and fluorescence microscopy also showed that quercetin, luteolin, and epigallocatechin gallate increased Akt substrate of 160 kDa phosphorylation and promoted 2-deoxy-D-glucose uptake by adipocytes under basal and inflammatory conditions. These findings suggested that quercetin, luteolin, and epigallocatechin gallate inhibited inflammation and promoted glucose disposal in adipocytes with the regulation of AMP-activated kinase and/or sirtuin 1.

Protective effects of oxymatrine on experimental diabetic nephropathy.

Abstract: Diabetic nephropathy, one of the most common and serious vascular complications of both type 1 and type 2 diabetes mellitus, has become a major contributor of end-stage renal failure. The aims of this study were to investigate the effects and possible underlying action mechanism(s) of oxymatrine on renal damage in diabetic rats. Diabetes was induced in male Sprague-Dawley rats by administering a high-fat diet and an intraperitoneal 30 mg/kg streptozotocin injection. The animals were treated orally with saline, metformin hydrochloride, and oxymatrine at 50, 100, and 150 mg/kg/day for 11 weeks. At the end of the treatment, renal tissue, blood, and urine samples were collected for histological and biochemical examination. The results revealed that oxymatrine significantly decreased blood glucose, urinary protein and albumin excretion, serum creatinine, and blood urea nitrogen in diabetic rats, and ameliorated diabetes-induced glomerular and tubular pathological changes. Furthermore, oxymatrine significantly prevented oxidative stress and reduced the contents of renal advanced glycation end products, transforming growth factor- β 1, connective tissue growth factor, and inflammatory cytokines in diabetic rats. All these results indicate that oxymatrine has protective effects on experimental diabetic nephropathy by multiple mechanisms.