Amarastelline A: A Fluorescent Alkaloid from Quassia amara and Its Properties in Living Cells

Quassinoids: Phytochemistry and antitumor prospect

Quassinoids, originating from the oxidative degradation of tetracyclic tirucallane triterpene, are a diverse class of secondary metabolites identifying from nature mostly in Simaroubaceae family. The crucial pharmacological activities and structural complexity of quassinoids have long fascinated scientists due to their medicinal uses, infamous toxicity, and unique biosynthesis. In the past few decades, 482 quassinoids, assigned to 6 skeletons, have been isolated and identified from plants. The names, classes, molecular formula, and plant sources of these secondary metabolites are collated here. This review will be a detailed update of the naturally occurring quassinoids reported from the plant kingdom, providing an in-depth discussion of their diversity, antitumor activities, structure-activity relationship.

Fluorescent Canthin-6-one Alkaloids from Simaba bahiensis: Isolation, Identification, and Cell-Labeling Properties

Canthin-6-one alkaloids, which are present in plants of the genus Simaba, are natural compounds that are capable of acting as fluorescent probes. However, the chemical composition and fluorescent properties of most species of this genus have not been analyzed. The objective of this study was to characterize the fluorescent properties of an extract of S. bahiensis and identify the chemical entities responsible for these properties. In addition, the cell-labeling properties of the fluorescent dye from A and of the isolated compounds were characterized by confocal fluorescence microscopy and flow cytometry. One quassinoid and three fluorescent alkaloids were isolated from S. bahiensis, all compounds were identified by using NMR spectroscopy and high-resolution mass spectrometry. Staining experiments and HPLC-FL analysis shown that canthin-6-one alkaloids are the main green fluorescent compounds in the analyzed dyes. All compounds evaluated showed a cytoplasmic marker with a residence time of 24 h. The present study is the first to describe the presence of canthin-6-one alkaloids in S. bahiensis, in addition to demonstrating promising cell-labeling properties of fluorescent compounds from S. bahiensis with broad emission wavelengths.

Antimalarial plants with potential male-factor antifertility properties

Malaria, caused mainly by Plasmodium falciparum among other Plasmodium species, is one of the main causes of death from parasitic diseases. Malaria is still a health problem mainly because of the cost of effective antimalarial drugs and the growing parasite resistance to conventional antimalarial drugs, making a great proportion of the people in malaria endemic countries dependent on plants for its treatment. Corollary, a large number of the rural populations consume antimalarial herbal preparations in large or excessive quantities despite the fact that it has been reported that some of them could cause male-factor infertility, a growing global health concern. Few studies have compiled information on the scientifically validated male-factor antifertility effects of these antimalarial plant remedies. The aim of this review therefore is to compile information on commonly used antimalarial plant remedies that have been experimentally validated as having male-factor antifertility effects. Thus, antimalarial plant remedies with experimentally confirmed male-factor antifertility potentials and compounds isolated from them are identified and discussed. The male-factor antifertility effects of these plants include reduction of sperm quality, regulation of reproductive hormone levels and induction of lipid peroxidation. Indiscriminate use of such antimalarial plants is discouraged when male contraception is not desired.

Construction of Canthin-5,6-diones via Termolecular Condensation Reaction: Studies on Synthesis of Amarastelline A

A termolecular condensation reaction of harmane, alkyl halide, and dimethyl oxalate has been developed for the construction of a variety of canthin-5,6-diones. The carbon skeleton of amarastelline A, a fluorescent canthin alkaloid, was synthesized in 99.8% yield by applying this procedure.

Fluorescent natural products as probes and tracers in biology

Fluorescence is a remarkable property of many natural products in addition to their medicinal and biological value. Herein, we provide a review of these peculiar secondary metabolites to stimulate prospecting of them as original fluorescent tracers, endowed with unique photophysical properties and with applications in most fields of biology.

Fruitful Decades for Canthin-6-ones from 1952 to 2015: Biosynthesis, Chemistry, and Biological Activities

In this review, more than 60 natural canthin-6-one alkaloids and their structures are considered. The biosynthesis, efficient and classic synthetic approaches, and biological activities of canthin-6-one alkaloids, from 1952 to 2015, are discussed. From an analysis of their structural properties and an investigation of the literature, possible future trends for canthin-6-one alkaloids are proposed. The information reported will be helpful in future research on canthin-6-one alkaloids.

The Cytotoxic Activity of Diterpenoids fromIsodonspecies

Fifteen Isodon diterpenoids (1–15) were evaluated for their cytotoxic activity against HeLa and HL-60 human cancer cell lines, and against murine vincristine (VCR)-resistant P388 cells. Kamebanin (14) showed efficient cytotoxic activity against HeLa and HL-60 cells. In addition, although dihydroenmein (2) and trichorabdal B (7) were inactive against several tested cell types, they were found to have cytotoxic-enhancing activity of VCR against VCR-resistant P388 cells.