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At least 217 records · Page 12Linked to original sources
PubMed1998

Neuromuscular blocking activity of methanolic extract of Piper sarmentosum leaves in the rat phrenic nerve-hemidiaphragm preparation.

Methanolic extract of Piper sarmentosum Roxb. (Piperaceae) leaves was studied for the neuromuscular blocking activity in rat phrenic nerve-hemidiaphragm preparations. The plant extract, at concentrations of 3.2, 4.0, 4.8 and 6.4 mg/ml, exhibited an initially transient increase in twitch tension which was followed by a marked dose-related neurally-evoked twitch depression. The neuromuscular blocking effect produced by the plant extract was compared with d-tubocurarine (dTC) and succinylcholine (SCh). The EC50 for neurally-evoked twitch depression of the extract, dTC and SCh was 4.07 mg/ml, 1.1 microM and 15 microM, respectively. The neurally-evoked twitch depression produced by the extract was partially antagonized by tetraethylammonium (TEA) but not by neostigmine (NS). These findings suggested that the plant extract possessed a marked neuromuscular blocking activity at the neuromuscular junction and a possible mechanism which was likely to inhibit neurotransmitter (acetylcholine) release at the presynaptic terminal.

Action Potentials↗
PubMed2002

Novel compounds from Piper methysticum Forst (Kava Kava) roots and their effect on cyclooxygenase enzyme.

Milled Piper methysticum roots were extracted sequentially with hot water and methanol. Cyclooxygenase (COX) enzyme inhibitory assay directed purification of the methanol extract yielded bornyl esters of 3,4-methylenedioxy cinnamic acid (1) and cinnamic acid (2), pinostrobin (3), flavokawain B (4), and 5,7-dimethoxyflavanone (5). The structures of compounds 1-5 were accomplished by spectral experiments. The aqueous extract contained previously reported kava lactones, as confirmed by TLC analysis. Compounds 3 and 5 were isolated for the first time from kava kava roots. Compound 4 showed the highest COX-I inhibitory activity at 100 microg/mL. All the compounds tested gave good COX-I and moderate COX-II enzyme inhibitory activities at 100 microg/mL. This is the first report of COX-I and -II inhibitory activities for compounds 1-5.

Cinnamates↗
PubMed2002

A piperidine amide extracted from Piper longum L. fruit shows activity against Aedes aegypti mosquito larvae.

Mosquito larvicidal activity of Piper longum fruit-derived materials against the fourth-instar larvae of Aedes aegypti was examined. A crude methanol extract of P. longum fruits was found to be active against the larvae, and the hexane fraction of the methanol extract showed a strong larvicidal activity of 100% mortality. The biologically active component of P. longum fruits was characterized as pipernonaline by spectroscopic analyses. The LC(50) value of pipernonaline was 0.25 mg/L. The toxicity of pipernonaline is comparable to that of pirimiphos-methyl as a mosquito larvicide. In tests with available components derived from P. longum, no activity was observed with piperettine, piperine, or piperlongumine.

Aedes↗
PubMed2006

In vitro cytotoxicity of nonpolar constituents from different parts of kava plant (Piper methysticum).

Kava (Piper methysticum), a perennial shrub native to the South Pacific islands, has been used to relieve anxiety. Recently, several cases of severe hepatotoxicity have been reported from the consumption of dietary supplements containing kava. It is unclear whether the kava constituents, kavalactones, are responsible for the associated hepatotoxicity. To investigate the key components responsible for the liver toxicity, bioassay-guided fractionation was carried out in this study. Kava roots, leaves, and stem peelings were extracted with methanol, and the resulting residues were subjected to partition with a different polarity of solvents (hexane, ethyl acetate, n-butanol, and water) for evaluation of their cytotoxicity on HepG2 cells based on the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and lactate dehydrogenase and aspartate aminotransferase enzyme leakage assays. Organic solvent fractions displayed a much stronger cytotoxicity than water fractions for all parts of kava. The hexane fraction of the root exhibited stronger cytotoxic effects than fractions of root extracted with other solvents or extracts from the other parts of kava. Further investigations using bioassay-directed isolation and analysis of the hexane fraction indicated that the compound responsible for the cytotoxicity was flavokavain B. The identity of the compound was confirmed by (1)H and (13) C NMR and MS techniques.

Aspartate Aminotransferases↗
PubMed2006

Determination of kavalactones in dried kava (Piper methysticum) powder using near-infrared reflectance spectroscopy and partial least-squares regression.

Kava (Piper methysticum Forst F.), or àwa in the Hawaiian language, has been used for thousands of years by the people of the South Pacific Islands, in particular Fiji, Vanuatu, Tonga, and Samoa, for social and ceremonial occasions. Kava has the unique ability to promote a state of relaxation without the loss of mental alertness. Kava recently became part of the herbal pharmacopoeia throughout the United States and Europe because of its anxiolytic properties. The active compounds are collectively called kavalactones (or kava pyrones). The need for a less time-consuming and costly method to determine the concentration of kavalactones in dried kava is urgent. The combination of near-infrared reflectance spectroscopy (NIRS) and partial least-squares (PLS) methods has been found to be a convenient, versatile, and rapid analytical tool for determination of kavalactones in dried kava powder. Calibration equations were developed based on the analyses of 110 samples with variable physical and chemical properties collected over time from Hawaii kava growers and validated by analyses of a set of 12 samples with unknown kavalactones concentration. All six major kavalactones and the total kavalactones were measured using NIRS with accuracy acceptable for commercial use. The NIRS measurements are reproducible and have a repeatability on a par with HPLC methods.

Anti-Anxiety Agents↗
PubMed2002

Antifungal activity of benzoic acid derivatives from Piper lanceaefolium.

Bioactivity-guided fractionation of a methanol extract from the leaves of Piper lanceaefolium resulted in the isolation of four new benzoic acid derivatives (1-4), together with taboganic acid, pinocembrin, and pinocembrin chalcone. Lanceaefolic acid methyl ester (3) and pinocembrin chalcone displayed activity against Candida albicans with a minimal inhibitory concentration value of 100 microg/mL in both cases.

Antifungal Agents↗
PubMedDate not supplied

Cytotoxic pyridone alkaloids from the leaves of Piper aborescens.

Bioactivity-guided fractionation of a CHCl3 extract of the leaves of Piper aborescens afforded a new cytotoxic pyridone alkaloid, N-(3-methoxy-4,5-methylenedioxydihydrocinnamoyl)-delta 3-pyridin-2-one [1], as well as three known cytotoxic pyridone alkaloids, N-(3-methoxy-4,5-methylenedioxycinnamoyl)-delta 3-pyridin-2-one [2], piplartine [3], and piplartine dimer A [4].

Alkaloids↗
PubMed1994

Cytotoxic and antibacterial dihydrochalcones from Piper aduncum.

Bioactivity-guided fractionation of a CH2Cl2 extract from the leaves of Piper aduncum afforded three new dihydrochalcones, piperaduncins A [3], B [4], and C [5], as well as two known dihydrochalcones, 2',6'-dihydroxy-4'-methoxydihydrochalcone [1] and 2',6',4-trihydroxy-4'-methoxydihydrochalcone [2] (asebogenin), together with sakuranetin, anodendroic acid methyl ester, and the carotenoid lutein. The structures of the isolates were elucidated by spectroscopic methods, mainly 1D- and 2D nmr spectroscopy. The proposed stereochemistry for compound 4 was deduced by NOESY spectroscopy and the corresponding energy minimum was established by molecular modelling calculations and translated into a 3D structure.

Animals↗
PubMed1995

The isolation and structural elucidation of three new neolignans, piperulins [corrected] A, B, and C, as platelet activating factor receptor antagonists from Piper puberulum.

Three new neolignans, piperulins [corrected] A [1], B [2], and C [3], were isolated from Piper puberulum. Their structures and relative stereochemistries were determined from spectral data and the X-ray crystallographic analysis of 1. Compounds 1 and 3 inhibit specific platelet activating factor receptor binding with IC50 values of 7.3 and 5.7 microM, respectively.

Animals↗
PubMed1996

Insecticidal neolignans from Piper decurrens.

2,3-Dihydro-2-(4'-hydroxyphenyl)-3-methyl-5(E)-propenylbenzofuran (conocarpan) (1), 2-(4'-hydroxy-3'-methoxyphenyl)-3-methyl-5(E)- propenylbenzofuran (eupomatenoid-5) (2), and 2-(4'- hydroxyphenyl)-3-methyl-5(E)-propenylbenzofuran (eupomatenoid-6) (3), three known neolignans found for the first time in a species of the Piperaceae, were isolated from Piper decurrens via insecticidal bioassay-guided fractionation, along with a small quantity of a new related compound, 2,3-dihydro-5-formyl-2-(4'-hydroxyphenyl)-3-methylbenzofuran (decurrenal) (4), and 3,7,11,15-tetramethyl-2(E)-hexadecen-1-ol (trans-phytol).

Animals↗
PubMed1997

Methyl 4-hydroxy-3-(3'-methyl-2'-butenyl)benzoate, major insecticidal principle from Piper guanacastensis.

The CHCl3-soluble extract of Piper guanacastensis (Piperaceae) was found to have noteworthy insecticidal activity to Aedes atropalpus mosquito larvae (LC50 80.5 micrograms/mL). Bioassay-guided fractionation afforded methyl 4-hydroxy-3-(3'-methyl-2'-butenyl)benzoate (1) as the major bioactive constituent (LC50 20.5 micrograms/mL). The separation of compound 1 from its transesterification artifact (2), ethyl 4-hydroxy-3-(3'-methyl-2'-butenyl)benzoate, was achieved by recycling reversed-phase HPLC. The flavonoids acacetin, chrysin, and pinostrobin were also isolated from the active fraction but did not display insecticidal properties.

Aedes↗
PubMed1998

Antifungal amide from leaves of Piper hispidum.

Bioactivity-guided fractionation of a CH2Cl2 extract from leaves of Piper hispidum (Piperaceae) yielded a new pyrrolidine amide, N-[7-(3',4'-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl] pyrrolidine 1, in addition to two known amides N-[5-(3', 4'-methylenedioxyphenyl)-2(E)-pentadienoyl] pyrrolidine and N-[2-(3', 4'-methylenedioxy-6'-methoxyphenyl)-2(Z)-propenoyl]pyrrolidine. The structure of compound 1 was elucidated by interpretation of spectral data, including ES-MS. Compound 1 showed antifungal activity against Cladosporium sphaerospermum.

Antifungal Agents↗
PubMed1998

Gibbilimbols A-D, cytotoxic and antibacterial alkenylphenols from Piper gibbilimbum.

Fractionation of the petroleum ether extract from the leaves of Piper gibbilimbum collected in Papua New Guinea afforded four new alkenylphenols, gibbilimbols A-D (1-4). The structures of the isolates were elucidated by spectroscopic methods, mainly 1D- and 2D-NMR spectroscopy. Gibbilimbols A-D were found to be toxic to brine shrimp with an LC50 of approximately 5 microg/mL. Gibbilimbols A-D were further found to be cytotoxic toward KB nasopharyngal carcinoma cells (ED50 7.8-2.1 microg/mL). All isolates also showed antibacterial activity toward Staphylococcus epidermidis and Bacillus cereus.

Anti-Bacterial Agents↗
PubMed1999

Arieianal, a prenylated benzoic acid from piper arieianum

A new prenylated benzoic acid, arieianal [3,4-dihydroxy-5-(E,E, E-11'-formyl-3',7',15'-trimethylhexadeca-2',6',10', 14'-tetraenyl)benzoic acid, 1], has been isolated from the leaves of Piper arieianum and assigned this structure on the basis of its spectral data.

Journal Article↗
PubMed2003

Identification of novel electrophilic metabolites of piper methysticum Forst (Kava).

Dietary supplements containing Piper methysticum Forst. (kava) have been implicated in multiple cases of liver injury in humans, including 10 recently reviewed cases in which patients required liver transplantation following the usage of kava-containing products (Centers for Disease Control and Prevention, reprinted. (2003) J. Am. Med. Assoc. 289, 36-37). To investigate a possible mechanism(s) of kava-induced hepatotoxicity, an extract of kava was incubated in vitro with hepatic microsomes, NADPH, and GSH. Electrophilic intermediates that were generated via metabolic activation were trapped as GSH conjugates and removed from the protein mixture using ultrafiltration. Positive ion electrospray LC-MS/MS with precursor ion scanning was used for the selective detection of GSH conjugates, and LC-MS(n) product ion scanning was used to elucidate their structures. Using this in vitro MS-based screening assay, two novel electrophilic metabolites of kava, 11,12-dihydroxy-7,8-dihydrokavain-o-quinone and 11,12-dihydroxykavain-o-quinone, were identified. Mercapturic acids of these quinoid species were not detected in the urine of a human volunteer following ingestion of a dietary supplement that contained kava; instead, the corresponding catechols were metabolized extensively to glucuronic acid and sulfate conjugates. These observations indicate that quinoid metabolites, under most circumstances, are probably not formed in substantial quantities following the ingestion of moderate doses of kava. However, the formation of electrophilic quinoid metabolites by hepatic microsomes in vitro suggests that such metabolites might contribute to hepatotoxicity in humans when metabolic pathways are altered (e.g., because of a drug interaction, genetic difference in enzyme expression, etc.) or if conjugation pathways become saturated.

Acetylcysteine↗
PubMed1998

Toxicity studies in mice of common spices, Cinnamomum zeylanicum bark and Piper longum fruits.

Acute (24 hours) and chronic (90 days) oral toxicity studies on the ethanolic extracts of common spices Cinnamomum zeylanicum Nees bark and Piper longum L. fruits were carried out in mice. Acute dosages were 0.5, 1.0 and 3 g/kg while the chronic dosage was 100 mg/kg/day. All external morphological, hematological and spermatogenic changes, in addition to body weight and vital organ weights, were recorded. The extracts of both the plants caused no significant acute or chronic mortality compared to the control during this study. During chronic treatment there was no significant change in the pre- and post treatment body weight of the test animals while the weight gain in the control group was significant. C. zeylanicum treatment caused reduction in liver weight while P. longum caused a significant increase in the weight of the lungs and spleen of the treated animals compared to the control. Hematological studies revealed a significant fall in hemoglobin level of C. zeylanicum treated animals. Both of the extracts induced a significant increase in reproductive organ weights, sperm motility, sperm count and failed to illicit any spermatotoxic effect.

Animals↗
PubMed2002

[Piper methysticum (kava) under discussion: observations on quality, effectiveness and safety].

Worldwide the application for a drug registration follows three basic principles: the proof of quality, efficacy and safety. In the following the applicability of these three principles on extracts from roots of the medicinal plant Kava (Piper methysticum) will be examined in the light of the current discussion of possible hepatic side effects ratio.

Adverse Drug Reaction Reporting Systems↗