Absolute configuration of indoline alkaloids from Geissospermum reticulatum

Antioxidant, Cytotoxic, and Antiproliferative Activities and Total Polyphenol Contents of the Extracts of Geissospermum reticulatum Bark

Geissospermum species are medically important plants due to their health-promoting effects. The objective of this study was to determine the antioxidant ability and antiproliferative and cytotoxic effects of infusions, tinctures, and ethanolic extracts of Geissospermum reticulatum barks in relation to the contents of total phenolics and flavonoids. Seven samples of barks were collected in various regions of Peruvian Amazonia. We found that the amount of total phenolics in the studied products varied from 212.40 ± 0.69 to 1253.92 ± 11.20 mg GAE/kg. In our study there is a correlation (R² = 0.7947) between the results of antioxidants assays: FRAP and ORAC for tinctures, infusions, and ethanolic extracts of G. reticulatum barks. We have also observed antiproliferative activities of the ethanolic extracts on normal T-cells. These extracts have caused death on malignant cell lines (THP-1 and HL-60) and this data correlates well with their antioxidant capacity measured by ORAC method. Interestingly, the highest concentration of the ethanolic extract was not toxic in the zebrafish embryo developmental assay. Our results indicate that G. reticulatum is rich in antioxidants and have cytotoxic and antiproliferative properties. The data suggests potential immunosuppressive role of the extracts. This is the first study presenting the results of chemical and biological analysis of multiple preparations from G. reticulatum.

IR and Vibrational Circular Dichroism Spectroscopy of Matrine- and Artemisinin-Type Herbal Products: Stereochemical Characterization and Solvent Effects

Five Chinese herbal medicines--matrine, oxymatrine, sophoridine, artemisinin, and dihydroartemisinin--were investigated using vibrational circular dichroism (VCD) experiments and density functional theory calculations to extract their stereochemical information. The three matrine-type alkaloids are available from the dry roots of Sophora flavescens and have long been used in various traditional Chinese herbal medicines to combat diseases such as cancer and cardiac arrhythmia. Artemisinin and the related dihydroartemisinin, discovered in 1979 by Professor Youyou Tu, a 2015 Nobel laureate in medicine, are effective drugs for the treatment of malaria. The VCD measurements were carried out in CDCl3 and DMSO-d6, two solvents with different dielectric constants and hydrogen-bonding characteristics. A "clusters-in-a-liquid" approach was used to model both explicit and implicit solvent effects. The studies show that effectively accounting for solvent effects is critical to using IR and VCD spectroscopy to provide unique spectroscopic features to differentiate the potential stereoisomers of these Chinese herbal medicines.

Recent advances in the use of vibrational chiroptical spectroscopic methods for stereochemical characterization of natural products

A comprehensive look into application of vibrational optical activity methods for conformational and configurational assignments in natural product molecules over the last 15 years is provided.

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

This review summarizes the isolation, structure determination, total syntheses and biological activities of simple indole alkaloids and those with a nonrearranged monoterpenoid unit, with literature coverage from 2012 to 2013.

Antiparasitic Indole Alkaloids from Aspidosperma desmanthum and A. spruceanum from the Peruvian Amazonia

Twenty-three indole alkaloids were isolated from Aspidosperma desmanthum and A. spruceanum. Alkaloids 1-4 were isolated from the leaves, 5-8 from the stem bark and 9-15 from the root bark of A. desmanthum. Alkaloids 5, 11, 16, 17 and 19 were isolated from the stem bark, 18 and 20-22 from the root bark and 23 from the flowers of A. spruceanum. Compounds 4, 14, and 15 have not been previously reported as natural products while 16 and 20 have been isolated for the first time from the genus Aspidosperma. Their structures were determined by spectroscopic techniques including 1D and 2D NMR experiments (COSY, NOESY, HSQC, HMBC). The antiparasitic activity of these compounds was tested against Trypanosoma cruzi and Leishmania infantum and their non-specific cytotoxicity on mammalian cells. The most active compounds were 10, 12, 13, and 14 from A. desmanthum, and 19, 21 and 22 from A. spruceanum. Aspidolimine (10) aspidocarpine (12) and tubotaiwine (21) showed selective activity against L. infantum.