Bis-nor-diterpene from Cnidoscolus quercifolius (Euphorbiaceae) induces tubulin depolymerization-mediated apoptosis in BRAF-mutated melanoma cells

A phytochemical investigation of cytotoxic extract and fractions of Cnidoscolus quercifolius Pohl led to isolation of five terpenoids, including three lupane-type triterpenes (1-3) and two bis-nor-diterpenes (4-5). Compounds 4 (phyllacanthone) and 5 (favelanone) are commonly found in this species and have unique chemical structure. Although their cytotoxic activity against cancer cells has been previously reported, the anticancer potential of these molecules remains poorly explored. In this paper, the antimelanoma potential of phyllacanthone (PHY) was described for the first time. Cell viability assay showed a promising cytotoxic activity (IC₅₀ = 40.9 μM) against chemoresistant human melanoma cells expressing the BRAF oncogenic mutation (A2058 cell line). After 72 h of treatment, PHY inhibited cell migration and induced apoptosis and cell cycle arrest (p < 0.05). Immunofluorescence assay showed that the pro-apoptotic effect of PHY is probably associated with tubulin depolymerization, resulting in cytoskeleton disruption of melanoma cells. Molecular docking investigation confirmed this hypothesis given that satisfactory interaction between PHY and tubulin was observed, particularly at the colchicine binding site. These results suggest PHY from C. quercifolius could be potential leader for the design of new antimelanoma drugs.

New ent-kaurene-type nor-diterpene and other compounds isolated from Annona vepretorum Mart. (Annonaceae)

A new nor-ent-kaurene diterpene and ten other compounds were isolated from Annona vepretorum stems, including four kaurene diterpenes, three alkamides, one sesquiterpene and two steroids. Their chemical structures were elucidated using spectroscopic methods, including 1D-, 2D-NMR, and HRESIMS. The absolute configuration of compounds 1, 5, 8, 9 and 10 was confirmed by CD experiments. Compounds 1-5 and 8-10 were evaluated for cytotoxic activity using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) MTT method, against three human carcinoma cell lines: human colon (HCT-116), glioblastoma (SF295) and prostate (PC3). However, all isolated compounds exhibited low cytotoxic activity.

Phytochemical and pharmacological aspects of Cnidoscolus Pohl species: A systematic review

BACKGROUND

Cnidoscolus is a genus belonging to the Euphorbiaceae family, distributed in South American countries, such as Mexico and Brazil, which includes several species widely used in folk medicine. However, the genus is not sufficiently exploited from a chemical and pharmacological point of view.

HYPOTHESIS/PURPOSE

This paper aims to present a systematic review of known pharmacological and chemical aspects from Cnidoscolus, an important genus for South America research groups on medicinal plants. In this article, we highlight the importance of Cnidoscolus species in the search for new bioactive molecules.

STUDY DESIGN

A systematic review was conducted in order to collect chemical and pharmacological information on species of this genus in the last 25 years.

METHODS

Literature search was performed through specialized databases (PUBMED, LILACS, SCIELO, Science Direct and Web of Science) using different combinations of the following keywords: Cnidoscolus, phytochemistry, pharmacological activity. For the selection of the manuscripts, two independent investigators (RGOJ and CAAF) first selected the articles according to the title, then to the abstract and finally through an analysis of the full-text publication. All selected manuscripts were analyzed for year of publication, country where the research was performed, reported plant species, isolated chemical compounds and evaluated biological activities.

RESULTS

Most of the studies involving Cnidoscolus were conducted by research groups located in Brazil, Nigeria and Mexico. Regarding the annual evolution of the publications, a larger number of articles published in 2014 were observed. Flavonoids, triterpenes and diterpenes represent the main classes of secondary metabolites that have been isolated from Cnidoscolus. In terms of the pharmacological investigations, C. aconitifolius, C. chayamansa and C. quercifolius are considered the most studied species, with different pharmacological activities.

CONCLUSION

All findings indicate that Cnidoscolus is an important genus of the Euphorbiaceae family. However, considering its chemical and pharmacological importance, the studies developed with Cnidoscolus species are still limited, representing an opportunity to investigate new bioactive molecules.