Ge Lin

Bio: Ge Lin is an academic researcher from The Chinese University of Hong Kong. The author has contributed to research in topics: Stemona tuberosa & Stemona. The author has an hindex of 5, co-authored 7 publications receiving 245 citations.

Antitussive activity of Stemona alkaloids from Stemona tuberosa.

Abstract: Bioactivity-directed fractionation of the crude extract of Stemona tuberosa led to the isolation and characterization of four new stenine-type Stemona alkaloids, namely tuberostemonine J ( 2), tuberostemonine H ( 3), epi-bisdehydrotuberostemonine J ( 4) and neostenine ( 5), together with the known neotuberostemonine ( 1). These five isolated alkaloids were examined for antitussive activity in guinea pig after cough induction by citric acid aerosol stimulation. In this report, we demonstrated, for the first time, that compounds 1 and 5 showed significant antitussive activities. Further study of the structure-activity relationship on these isolated alkaloids and two synthetic analogues revealed that the saturated tricyclic pyrrolo[3,2,1- jk] benzazepine nucleus is the primary key structure contributing to the antitussive activity and all cis configurations at the three ring junctions are the optimal structure for the antitussive activity of stenine-type Stemona alkaloids.

Determination of hepatotoxic pyrrolizidine alkaloids by on-line high performance liquid chromatography mass spectrometry with an electrospray interface.

Abstract: The present study describes the determination of two different types of hepatotoxic pyrrolizidine alkaloids (PAs) and also distinguishing the hepatotoxic PAs from non-toxic ones by both in-source collision-induced dissociation high performance liquid chromatography mass spectrometry (CID-HPLC/MS) and HPLC/MS/MS (CID in the collision cell), using electrospray ionization. The mass spectra provided molecular ions and characteristic fragment ions, which could be used readily for a rapid identification of different types of PAs. Applications of both in-source CID-HPLC/MS and HPLC/MS/MS analytical methods were successful for the determination of PAs in blood samples obtained from rats dosed with PAs and in the PA-containing plant. The results demonstrated that the developed HPLC/MS methods with two different CID techniques provided a very simple and rapid analysis for an unequivocal diagnosis of PA poisoning and for definitive identification of PAs in plants or herbal medicines.

Authentication and Quality Assessment of the Antitussive Herb Baibu (Radix Stemonae)

Abstract: The Chinese herb Radix Stemonae, or Baibu in Chinese, has been used for treating coughing for over 15 centuries. According to the Pharmacopoeia of the People's Republic of China, it comes from the tuberous roots of three species of Stemona . The properties of multiple origins of source plants and existence of multiple antitussive components made the authentication and quality assessment extremely difficult. This review provides an up-to-date coverage of scientific advances in species identification and authentication among the three genuine species and substitutes derived from the genus Asparagus , characterization of the Stemona alkaloids including chemical diversities among the three genuine species and among the major commodity derived from Stemona tuberosa from different locations, identification of the antitussive components and mechanisms of action, clarification of adverse reactions, and, based on all these information, development of quality assessment methods.

Isolation and Stereochemistry of Two New Alkaloids from Stemona tuberosa

Abstract: Two new stenine-type alkaloids, neotuberostemonol ( 3 ) and neotuberostemoninol ( 4 ), along with the known compound neotuberostemonine ( 2 ), were isolated from Stemona tuberosa Lour. Their structures were characterized by X-ray crystallography in combination with spectroscopic methods, and their absolute configurations were inferred from the known configuration of tuberostemonine ( 1 ). In the crystalline state, weak C–H⋯O hydrogen bonds play an important role in the molecular packing of 3 and 4 .

Pyrrolizidine alkaloids--genotoxicity, metabolism enzymes, metabolic activation, and mechanisms.

Abstract: Pyrrolizidine alkaloid-containing plants are widely distributed in the world and are probably the most common poisonous plants affecting livestock, wildlife, and humans. Because of their abundance and potent toxicities, the mechanisms by which pyrrolizidine alkaloids induce genotoxicities, particularly carcinogenicity, were extensively studied for several decades but not exclusively elucidated until recently. To date, the pyrrolizidine alkaloid-induced genotoxicities were revealed to be elicited by the hepatic metabolism of these naturally occurring toxins. In this review, we present updated information on the metabolism, metabolizing enzymes, and the mechanisms by which pyrrolizidine alkaloids exert genotoxicity and tumorigenicity.

Chemical markers for the quality control of herbal medicines: an overview

Abstract: Selection of chemical markers is crucial for the quality control of herbal medicines, including authentication of genuine species, harvesting the best quality raw materials, evaluation of post-harvesting handling, assessment of intermediates and finished products, and detection of harmful or toxic ingredients. Ideal chemical markers should be the therapeutic components of herbal medicines. However, for most herbal medicines, the therapeutic components have not been fully elucidated or easily monitored. Bioactive, characteristic, main, synergistic, correlative, toxic and general components may be selected. This article reviews the effective use of chemical markers in the quality control of herbal medicines including the selection criteria considering the roles and physicochemical factors which may affect the effective use of chemical markers.