Pyrrolizidine alkaloids from Eupatorium portoricense

Three pyrrolizidine alkaloids were isolated from Eupatorium portoricense and their structures elucidated by spectroscopic methods as (-)-viridifloryl-supinidine (amabiline), (-)-viridifloryl-heliotridine (echinatine), and C12- O-acetyl-(-)-viridifloryl-heliotridine (O(12)-acetylechinatine).     

Pyrrolizidine alkaloids from Cynoglossum furcatum

Two new pyrrolizidine alkaloids have been isolated from the roots of Cynoglossum furcatum. On the basis of chemical and spectroscopic evidence, structures of the compounds have been elucidated. They are lactodine (3), a monoster alkaloid and viridinatine (4), a pyrrolizidine diester alkaloid. The structure of lactodine is elucidated as 9-O-(-)lactyl heliotridine and viridinatine as 7-O-(-)viridifloryl echinatine.     

Pyrrolizidine alkaloids from Cynoglossum furcatum

Two new pyrrolizidine alkaloids have been isolated from the roots of Cynoglossum furcatum. On the basis of chemical and spectroscopic evidence, structures of the compounds have been elucidated. They are lactodine (3), a monoster alkaloid and viridinatine (4), a pyrrolizidine diester alkaloid. The structure of lactodine is elucidated as 9-O-(-)lactyl heliotridine and viridinatine as 7-O-(-)viridifloryl echinatine.     

Pyrrolizidine alkaloids of three species of senecio in British Columbia

A new alkaloid, 9- O-acetyl-7- O-angelyl-retronecine, was isolated from Senecio triangularis together with 7-O-angelyl-, 9-O-angelyl-, and 7-O-angelyl-9-O-sarracinylretronecine; S. pseudaureus and S. streptanthifolios yielded only retrorsine and senecionine.     

Pyrrolizidine alkaloids: Actions on muscarinic receptors in the guinea-pig ileum

1. Eleven pyrrolizidine alkaloids have been tested on the isolated guinea-pig ileum preparation.2. Platyphylline, supinine, heleurine and cynaustraline were more potent in antagonizing responses to acetylcholine and carbachol than responses to histamine. Their anticholinergic activity appeared to involve a competitive mechanism.3. Lasiocarpine, monocrotaline, spectabiline, sarracine, 7-angelylheliotridine, heliotrine and senecionine had similar antagonistic potencies against responses to both acetylcholine and histamine.4. The alkaloids had no appreciable activity as antagonists of acetylcholine in the isolated toad rectus abdominis preparation.5. These results are discussed with respect to interactions of the alkaloids at receptor sites involved in anticholinergic activity at the muscarinic receptor.     

Pyrrolizidine alkaloids,flavonoids and volatile compounds in the genus Eupatorium

Within the scope of a study of antitumour compounds in higher plants a survey is given concerning the presence of pyrrolizidine alkaloids, flavonoids and volatile compounds inEupatorium species. Preliminary results of a phytochemical study of these compounds inE. cannabinum are also presented. From the results of a GC-MS analysis of an alkaloid extract from aerial parts ofE. cannabinum the conclusion can be drawn, that the composition of pyrrolizidine alkaloids is more complicated than reported in literature. This is caused by the fact that different stereoisomers exist. The presence of at least two alkaloids with a molecular weight of 283 (supinine or isomers) and four alkaloids with a molecular weight of 299 (echinatine or isomers) could be shown. In subterranean plant material also other pyrrolizidine alkaloids are present. A great number of flavonoids, also as glycosides, have been shown inEupatorium species, often in low quantities. Rutin, present in manyEupatorium species, could not be detected in subterranean parts ofE. cannabinum. Relatively little attention has been paid to the analysis of volatile compounds (essential oils) ofEupatorium species. Thymol derivatives are often reported to be present inEupatorium species. Thirty-five compounds could be detected by means of a GC-MS analysis in the essential oil ofE. cannabinum about which no literature data were available.     

Pyrrolizidine alkaloids in plants used in the traditional medicine of Madagascar and the Mascarene islands

Pyrrolizidine alkaloids (PAs) can be hazardous to the health of humans and animals. Although their toxicity has been known for a long time, PA containing plants are still in use in many traditional medicines. Traditional healing systems have become of increasing interest as many people believe that they can be used without any risk and side effects. This also applies to the traditional medicine of Madagascar and the Mascarene island (Mauritius, Reunion, Rodriguez). Recent literature reports have recommended this traditional medicine because of its good efficacy and pharmacological properties. However, several plants are listed there which have already been described to contain toxic PAs or are suspected of containing them.     

Pyrrolizidine alkaloids: Organohalogen derivative isolated from Senecio jacobaea (Tansy Ragwort)

Senecio jacobaea (Tansy Ragwort) has previously been reported to contain 6 hepatotoxic pyrrolizidine alkaloids (PAs). Utilizing high pressure liquid chromatography (HPLC) plus mass spectrometry, 3 additional pyrrolizidine alkaloids are described, including a second chlorinated pyrrolizidine alkaloid. These additional pyrrolizidine alkaloids, through a variety of products, appear to pose an increased human health hazard.     

Characterization and Lifetime Dietary Risk Assessment of Eighteen Pyrrolizidine Alkaloids and Pyrrolizidine Alkaloid N-Oxides in New Zealand Honey

Pyrrolizidine alkaloids (PAs) are a large group of botanical toxins of concern, as they are considered genotoxic carcinogens, with long-term dietary exposure presenting an elevated risk of liver cancer. PAs can contaminate honey through honeybees visiting the flowers of PA-containing plant species. A program of monitoring New Zealand honey has been undertaken over several years to build a comprehensive dataset on the concentration, regional and seasonal distribution, and botanical origin of 18 PAs and PA N-oxides. A bespoke probabilistic exposure model has then been used to assess the averaged lifetime dietary risk to honey consumers, with exposures at each percentile of the model characterized for risk using a margin of exposure from the Joint World Health Organization and United Nations Food and Agriculture Organization Expert Committee on Food Additives (JECFA) Benchmark Dose. Survey findings identify the typical PA types for New Zealand honey as lycopsamine, echimidine, retrorsine and senecionine. Regional and seasonal variation is evident in the types and levels of total PAs, linked to the ranges and flowering times of certain plants. Over a lifetime basis, the average exposure an individual will receive through honey consumption is considered within tolerable levels, although there are uncertainties over high and brand-loyal consumers, and other dietary contributors. An average lifetime risk to the general population from PAs in honey is not expected. However, given the uncertainties in the assessment, risk management approaches to limit or reduce exposures through honey are still of value.