(−)-Veranigrine, a new steroidal alkaloid from Veratrum nigrum L

Veratrum nigrum L.: A comprehensive review of ethnopharmacology, phytochemistry, pharmacology, pharmacokinetics and metabolism, toxicity, and incompatibility

ETHNOPHARMACOLOGICAL RELEVANCE

Veratrum nigrum L. (V. nigrum) is a well-known herb with a lengthy history of use in Asian and European countries. V. nigrum has been traditionally used to treat epilepsy, hypertension, malignant sores, and stroke, and it possesses emetic and insecticide properties.

AIM OF THE REVIEW

This review summarized the ethnopharmacology, phytochemistry, pharmacology, pharmacokinetics and metabolism, and toxicity of V. nigrum as well as its incompatibility with other herbs. Current challenges in the use of V. nigrum and possible future research directions were also discussed.

MATERIALS AND METHODS

Information on V. nigrum was collected from electronic databases such as PubMed, Google Scholar, Web of Science, CNKI, and WanFang DATA; Masterpieces of Traditional Chinese Medicine; local Chinese Materia Medica Standards; and relevant documents.

RESULTS

In ethnomedical practice, V. nigrum has been used as an emetic and insecticide. Approximately 137 compounds have been isolated from V. nigrum, including alkaloids, stilbenes, flavonoids, organic acids, and esters. Its crude extracts and compounds have shown various effects, including anticancer, hypotensive, insecticidal, and antimicrobial activities as well as the ability to improve hemorheological abnormalities. Pharmacokinetic studies have indicated that veratramine (VAM) and jervine have high bioavailability and possibly enterohepatic circulation. In addition, the sex-related pharmacokinetic differences in V. nigrum alkaloids warrant further attention. Toxicological studies have indicated that cevanine-type alkaloids and VAM may be the main toxic components of V. nigrum, and purine metabolism disorders may be related to V. nigrum toxicity. Furthermore, the neurotoxicity and embryotoxicity of V. nigrum have also been observed. The quality control of V. nigrum and the mechanism underlying its incompatibility with other herbs also deserve further research and refinement.

CONCLUSION

This review summarized the existing information on V. nigrum, laying the foundation for further studies on this herb and its safe use. Among the various compounds present in V. nigrum, steroid alkaloids are the most numerous and have high content; furthermore, they are closely related to the pharmacological effects of V. nigrum, but their toxicity can not also be ignored. Given that toxicity is a critical issue limiting the clinical application of V. nigrum, more toxicological studies on V. nigrum and its active ingredients, especially steroid alkaloids, should be conducted in the future to further explore its toxicity targets and the underlying mechanisms and to provide more evidence and recommendations to enhance the safety of its clinical application.

Chemistry and bioactivities of natural steroidal alkaloids

Steroidal alkaloids possess the basic steroidal skeleton with a nitrogen atom in rings or side chains incorporated as an integral part of the molecule. They have demonstrated a wide range of biological activities, and some of them have even been developed as therapeutic drugs, such as abiraterone acetate (Zytiga^®), a blockbuster drug, which has been used for the treatment of prostate cancer. Structurally diverse natural steroidal alkaloids present a wide spectrum of biological activities, which are attractive for natural product chemistry and medicinal chemistry communities. This review comprehensively covers the structural classification, isolation and various biological activities of 697 natural steroidal alkaloids discovered from 1926 to October 2021, with 363 references being cited.

The Veratrum and Solanum alkaloids

This survey on steroidal alkaloids of the Veratrum and Solanum family isolated between 1974 and 2014 includes 187 compounds and 197 references. New developments in the chemistry and biology of this family of natural products with a special focus on the medicinal relevance of the jervanine alkaloid cyclopamine are discussed.

The Correlation between Chemical Composition, as Determined by UPLC-TOF-MS, and Acute Toxicity of Veratrum nigrum L. and Radix paeoniae alba

The eighteen incompatible medicaments is an important theory in traditional Chinese medicine. The theory suggests that drugs in the eighteen incompatible medicaments can be toxic when used together. Veratrum nigrum L. and Radix paeoniae alba belong to the eighteen incompatible medicaments and have been prohibited for thousands of years. This study offers preliminary insight into the mechanism and chemical constituents responsible for the incompatibility and toxicity of these two agents. Specifically, we performed toxicology studies to identify and quantify the constituent substances of the two agents. Experiments revealed that acute toxicity increases when the dose of V. nigrum L. is higher than, or equal to, RPA. UPLC-TOF-MS analysis showed that, although the volumes of V. nigrum L. were the same, the content of some veratrum alkaloids changed significantly and had a trend toward a highly positive correlation (|r| ≥ 0.8) with toxicity. This suggests that the increased toxicity of the V. nigrum L. and RPA combination was due mainly to increased content of the special veratrum alkaloids. The cytotoxicity of veratridine in SH-SY5Y cells was decreased with increasing paeoniflorin concentrations. This study provides insight into the mechanism behind the incompatibility theory of TCM.

Alkaloids derived from genus Veratrum and Peganum of Mongolian origin as multidrug resistance inhibitors of cancer cells

Alkaloids comprise one of the largest groups of plant secondary metabolites including vinca alkaloids. The ability of six alkaloids from Veratrum lobelianum, one from Veratrum nigrum and three from Peganum nigellastrum to modify transport activity of MDR1 was studied. Flow-cytometry in a multidrug-resistant human MDR1-gene-transfected mouse lymphoma cells (L5178Y) was applied. The inhibition of multidrug resistance was investigated by measuring the accumulation of rhodamine-123 in cancer cells. Veralosinine and veranigrine were the most effective resistance modifiers. In a checkerboard method veralosinine and veranigrine enhanced the antiproliferative effects of doxorubicin on MDR cells in combination. The structure-activity relationships were discussed.