Jacaranone glycosides from Senecio scandens

Jacaranone Derivatives with Antiproliferative Activity from Crepis pulchra and Relevance of This Group of Plant Metabolites

Jacaranones are a small group of specific plant metabolites with promising biological activities. The occurrence of jacaranones is limited to only a few plant families, with Asteraceae being the most abundant source of these compounds. Therefore, jacaranones can also serve as chemotaxonomic markers. Our phytochemical investigation of Crepis pulchra L. (Asteraceae) resulted in three jacaranone derivatives (jacaranone, 2,3-dihydro-2-hydroxyjacaranone, 2,3-dihydro-2-methoxyjacaranone), and (6R,9S)-3-oxo-α-ionol-β-d-glucopyranoside, fulgidic acid, 12,15-octadecadienoic acid methyl ester, scopoletin and apigenin-7-O-β-d-glucoside. This is the first report on the isolation of jacaranones from a species belonging to the Cichorioideae subfamily of Asteraceae. Jacaranone derivatives were subjected to an in vitro antiproliferative assay against a panel of human cancer cell lines (MCF-7, MDA-MB-231, HeLa, and C33A), revealing high or moderate activities, with IC₅₀ values ranging from 6.3 to 26.5 μM.

Chinese Herbal Medicine-induced Liver Injury

The widespread use of Chinese herbal medicine (CHM) and the associated adverse reactions has attracted the attention of researchers and physicians. Reports have shown that several types of CHM can cause liver injury, with increasing numbers of cases reported every year. The difficulty in characterizing CHM-induced liver injury stems from clinical manifestations, diagnosis and pathogenesis. The clinical manifestations are varied, but gastrointestinal symptoms are the majority. The Council for International Organizations of Medical Sciences scale is currently the most commonly used method for assessing causality in cases of medicine-induced liver injury with excellent sensitivity, specificity and predictive validity. However, the pathogenesis of CHM-induced liver injury is not well understood. The classic view encompasses a contribution from "toxic metabolites" that either elicit an immune response or directly affect cellular biochemical processes or functions. In addition, poor quality and inappropriate clinical use of CHMs contribute to safety concerns. To ensure the safe use of CHMs and decrease the number of hepatotoxic cases, clinicians, researchers and pharmaceutical companies should share responsibility by regulating clinical use, strengthening basic toxicology research and establishing a strict quality control system.

The importance of hyphenated techniques in the discovery of new lead compounds from nature

Nature represents an extraordinary reservoir of novel molecules and there is currently a resurgence of interest in natural products as a possible source of new lead compounds for introduction into therapeutical screening programmes. To discover new bioactive natural products, the dereplication of crude extracts performed prior to isolation work is of crucial importance for avoiding the tedious isolation of known constituents. In this respect, chemical screening strategies based on hyphenated techniques such as liquid chromatography-ultraviolet photodiode array detection, liquid chromatography-mass spectrometry, liquid chromatography tandom mass spectrometry and liquid chromatography-nuclear magnetic resonance (LC-NMR) are more and more extensively used. In the laboratory of Hostettmann's group, these analytical methods have been fully integrated into the isolation process and are used for the chemical screening of crude plant extracts, in complement with online or at-line bioassays, for rapid localisation and identification of new bioactive compounds. In this paper, possibilities and limitations of hyphenated techniques for de novo online natural product identification are discussed. As LC-NMR is playing a key role in this respect, the main part of the paper is dedicated to this technique. In particular, various ways of integrating NMR in the dereplication process are illustrated and strategies involving either direct or indirect hyphenation are presented.

Authentication of Senecio scandens and S. vulgaris based on the comprehensive secondary metabolic patterns gained by UPLC-DAD/ESI-MS

A secondary metabolic pattern using ultra-performance liquid chromatography (UPLC)-DAD/ESI-MS was constructed to gain chemical information for authentication of Senecio scandens (SS) and Senecio vulgaris (SV), the two representative species containing hepatotoxic pyrrolizidine alkaloids (HPAs). The metabolic pattern showed three groups of bioactive constituents: phenolic/aromatic acids, flavonoid glycosides and the HPAs. 47 peaks were identified including 19 phenolic/aromatic acids, 10 flavonoid glycosides and 18 PAs by direct comparison with the available reference compounds or deduced from the UV absorption and their ESI-MS fragmentation patterns. The two species could be authenticated diagnostically by their metabolic profiling of the three chromatographic fingerprints. Although both SS and SV contain PAs as the characteristic constituents, only 2 PAs, adonifoline and adonifoline N-oxide were detected in SS, while other 16 PAs were detected in SV, including the highly toxic senecionine, retrorsine, seneciphylline and their corresponding N-oxides. The concentration of PAs in SV is also higher than that in SS. The number and concentration of the phenolic compounds in SS were higher than in SV. Jacaranone derivatives were only detected in SS and jacaranone ethyl ester was detected as the predominant constituent. In the fingerprint of the n-butanol extracts, 10 quercetin and kaempferol glycosides derivatives were detected. 9 were found in SS and only 2 in SV. PAs, jacaranone derivatives and flavonoid glycosides can serve as the metabolic markers to distinguish the Senecio plants from each other, and provide evidence for their clinical application in the consideration of safety and efficacy.

Jacaranone-derived glucosidic esters from Jacaranda glabra and their activity against Plasmodium falciparum

In a survey of plants from Ecuador with antiprotozoal activity, Jacaranda glabra was found to show promising activity against the Plasmodium falciparum K1 strain. Subsequently, activity-guided isolation of the dichloromethane extract from the leaves of J. glabra afforded four new phenylethanoid glucosides containing jacaranone-type moieties (1-4), named jacaglabrosides A-D. Their chemical structures were identified using NMR spectroscopy and MS techniques. The compounds were found to be active in vitro against the P. falciparum K1 strain (IC(50) 1, 1.02; 2, 0.56; 3, 0.56; and 4, 0.55 microg/mL) and generally possessed a low cytotoxicity toward L-6 cells, with the exception of compound 1 (IC(50) 1, 8.3; 2, >90; 3, 87; and 4, 85 microg/mL).

Jacaranda--an ethnopharmacological and phytochemical review

The genus Jacaranda, an important representative of the tribe Tecomeae in the family Bignoniaceae, is interesting from both biological and chemical perspectives. In this review, a contemporary summary of biological and pharmacological research on Jacaranda species will be presented and critically evaluated. Significant findings in the treatment of protozoa-caused diseases as well as of skin illnesses have been presented in ethnobotanical reports and recent studies were performed on crude extracts for certain Jacaranda species. Jacaranone, the most important constituent isolated is known to possess anti-cancer activity. Recently, high cutaneous toxicity together with moderate activity against leishmaniasis was described. Very few additional data are available on the biological activities and cytotoxicity of pure compounds from Jacaranda. Thirteen of the forty-nine distinguished species of Jacaranda have been reported in scientific literature as ethnobotanically used or phytochemically investigated. However, information about a chemical profile is available only for six species. The following article gives a critical assessment of the literature to date and aims to show that the pharmaceutical potential of this genus has been underestimated and deserves closer attention.

Jacaranone analogs from Senecio scandens

Bioassay-guided fractionation of the ethanolic extract of Senecio scandens led to the isolation of four new compounds 4, 5, 7, and 8, along with four known jacaranone analogs (1, 2, 3, 6). Their structures were elucidated on the basis of spectral and chemical evidence. Compound 7 was obtained as a tautomeric mixture of alpha/beta-epimer. The cytotoxic activities of these compounds were evaluated. Among these, compounds 5 and 8 showed potent cytotoxicities. The benzoquinone derivative, jacaranone ethyl ester (1), was the major cytotoxic constituent in this plant with IC(50)s at a range of 0.5-1.0 microg/ml against various tumor cell lines. The SAR of these jacaranone analogs (1-8), isolated from S. scandens, was also discussed.

Identification of five hepatotoxic pyrrolizidine alkaloids in a commonly used traditional Chinese medicinal herb, Herba Senecionis scandentis (Qianliguang)

Senecio scandens Buch.-Ham is a plant source for a commonly used traditional Chinese medicinal (TCM) herb Qianliguang. A TCM herbal proprietary product containing Qianliguang as the major herb for the treatment of sinusitis has been used in China for several decades, and has also been exported to other regions and countries worldwide. In the present study, the aqueous extract of S. scandens collected in the Shanxi Province of China was determined, for the first time, to contain hepatotoxic and tumorigenic pyrrolizidine alkaloids (PAs) by using high-performance liquid chromatography/mass spectrometric (HPLC/MS) analysis in various scanning modes. A total of nine toxic and two non-toxic PAs were detected in the aqueous extract of S. scandens, of which six PAs, namely neoplatyphylline, senecionine, senecionine N-oxide, seneciphylline, seneciphylline N-oxide and senkirkine, were unequivocally characterized, while other PAs were tentatively assigned as jacobine, jacozine N-oxide (or erucifoline N-oxide), 7-tigloylplatynecine, usaramine and an isomer of yamataimine. The estimated total content of toxic PAs in S. scandens was 10.82 microg/g herb, which was significantly higher than that (> or =1 microg/g herb) recommended by Belgium and Germany not to be used clinically. Among the PAs definitively identified, senecionine, seneciphylline, and senkirkine are known tumorigens capable of inducing liver tumors in experimental animals, while seneciphylline N-oxide and senecionine N-oxide are probably tumorigenic due to their potential conversion into seneciphylline and senecionine via metabolic reduction in the body. Thus, the current finding of the presence of toxic/tumorigenic PAs in S. scandens challenges the safety of using this TCM herb and its proprietary products.