Amaryllidaceae Alkaloids from Lycoris radiata

A phytochemical investigation on bulbs of Lycoris radiata resulted in the isolation of three new Amaryllidaceae alkaloids, named 5,6‐dehydrodihydrolycorine ( 1 ), 6β‐acetoxycrinamine ( 2 ), and (+)‐8‐O‐acetylhomolycorine α‐N‐oxide ( 3 ), together with eleven known alkaloids, 4 – 14 . The structures of the new alkaloids were established by means of spectroscopic methods, and the known compounds were identified by comparison of their data with those in the literature. Compound 2 showed cytotoxicity against HL‐60, A‐549, and MCF‐7 cells, with IC₅₀ values of 8.1, 24.3, and 15.0 μM , respectively.     

Alkaloids from Hippeastrum morelianum Lem. (Amaryllidaceae)

The Amaryllidaceae family has proven to be a rich source of active molecules. As part of an ongoing project, we report a phytochemical study of Hippeastrum morelianum (Amaryllidaceae), from which we have isolated two homolycorine-type alkaloids, the new 2α,7-dimethoxyhomolycorine (1) and the poorly described candimine (2), as well as six known alkaloids: tazettine, pretazettine, 3-epimacronine, haemanthamine, hamayne and trisphaeridine. For reference purposes, the NMR of the isolated compounds was unequivocally described, based on 2D NMR measurements including (1)H-(1)H COSY, (1)H-(1)H NOESY, HSQC and HMBC.     

Alkaloids from Eucharis amazonica (Amaryllidaceae)

Thirteen alkaloids have been isolated from dried bulbs and leaves of flowering Eucharis amazonica (Amaryllidaceae). The alkaloids, 7-methoxyoxoassoanine, 6-O-methylpretazettine and apohaemanthamine, are reported for the first time from a natural source.     

Two New Indole Alkaloids from Tabernaemontana hystrix Steud. (Apocynaceae)

Two new monoterpene indole alkaloids named ibogamine‐7,8‐dione ( 1 ) and 12‐methoxyvoachalotine ( 2 ), and eight known ones, coronaridine ( 3 ), coronaridine hydroxyindolenine ( 4 ), 5‐oxocoronaridine ( 5 ), 3‐oxocoronaridine hydroxyindolenine ( 6 ), 3‐oxocoronaridine ( 7 ), vobasine ( 8 ), ibogamine ( 9 ), and olivacine ( 10 ), were isolated from a CH₂Cl₂ extract of the root bark from Tabernaemontana hystrix. The structures of the compounds were elucidated on the basis of spectroscopic data analyses, mainly ¹H‐ and ¹³C‐NMR, including 2D experiments (¹H,¹H‐COSY, HMBC, and HMQC).     

Alkaloids Analysis of Habranthus cardenasianus (Amaryllidaceae), Anti-Cholinesterase Activity and Biomass Production by Propagation Strategies

Plants in the Amaryllidaceae family synthesize a diversity of bioactive alkaloids. Some of these plant species are not abundant and have a low natural multiplication rate. The aims of this work were the alkaloids analysis of a Habranthus cardenasianus bulbs extract, the evaluation of its inhibitory activity against cholinesterases, and to test several propagation strategies for biomass production. Eleven compounds were characterized by GC-MS in the alkaloid extract, which showed a relatively high proportion of tazettine. The known alkaloids tazettine, haemanthamine, and the epimer mixture haemanthidine/6-epi-haemanthidine were isolated and identified by spectroscopic methods. Inhibitory cholinesterases activity was not detected. Three forms of propagation were performed: bulb propagation from seed, cut-induced bulb division, and micropropagated bulbs. Finally, different imbibition and post-collection times were evaluated in seed germination assays. The best propagation method was cut-induced bulb division with longitudinal cuts into quarters (T1) while the best conditions for seed germination were 0-day of post-collection and two days of imbibition. The alkaloids analyses of the H. cardenasianus bulbs showed that they are a source of anti-tumoral alkaloids, especially pretazettine (tazettine) and T1 is a sustainable strategy for its propagation and domestication to produce bioactive alkaloids.     

Alkaloids from Stems of Ervatamia yunnanensis (II)

The non-alkaloid chemical constituents, which were isolated from the stems of Ervatamia yunnanensis Tsiang (Apocynaceae), have been reported in previous paper 1. As a part of our continuing research on the isolation of active compounds for anti-addictive …     

Advances in the Chemical and Biological Characterization of Amaryllidaceae Alkaloids and Natural Analogues Isolated in the Last Decade

Amaryllidaceae are bulbous wild and cultivated plants well known for their beautiful flowers and pharmaceutical applications, essentially due to the alkaloids and flavonoids content. Hundreds of alkaloids have been isolated until now and several scientific publications reported their sources, chemical structures, and biological activities. During the last decade, some unstudied Amaryllidaceae plants were the object of in-depth investigations to isolate and chemically and biologically characterize new and already known alkaloids as well as some analogues. This review describes the isolation and chemical and biological characterization of the Amaryllidaceae alkaloids, and their analogues obtained in the last decade, focusing the discussion on the new ones.     

C19 and C20 Diterpene Alkaloids from Aconitum toxicum Rchb.

Acotoxinine ( 1 ), a new norditerpene alkaloid, was isolated from the roots of Aconitum toxicum Rchb ., together with the structurally related C₁₉ diterpene alkaloids neoline ( 2 ) and aconitine ( 3 ) and C₂₀ diterpene alkaloids songorine ( 4 ) and songoramine ( 5 ). The structures were elucidated by HR‐MS and advanced NMR methods, including ¹H‐NMR, JMOD, ¹H,¹H‐COSY, HSQC, and HMBC experiments. This is the first report of C₂₀ diterpenoid alkaloids in Aconitum toxicum.     

Immunosuppressive Sesquiterpene Pyridine Alkaloids from Tripterygium wilfordii Hook. f.

Tripterygium wilfordii Hook. f. is a well-known traditional Chinese medicine used to treat autoimmune diseases. Sesquiterpene pyridine alkaloids (SPAs) are a major class of components found in this herb that have piqued the interest of researchers due to their complex and diverse structures as well as significant biological activities. In this study, ten new SPAs, wilfordatine A–J (1–10), were isolated from the roots of T. wilfordii, along with ten known analogues (11–20). Their structures were primarily elucidated by extensive 1D and 2D NMR spectroscopic analysis. To search for more immunosuppressive ingredients related to the clinical efficacy of T. wilfordii, the total alkaloids (TA) and compounds 4, 5, and 9–16 were tested for their inhibitory effects on nuclear factor-kappa B (NF-κB) pathway in Lipopolysaccharide (LPS) induced HEK293/NF-κB-Luc cells. Among them, TA, compounds 5, 11, and 16 showed potent immunosuppressive activity, with IC₅₀ values of 7.25 μg/mL, 8.75 μM, 0.74 μM, and 15.66 μM, respectively, and no influence on the cell viability at a concentration of 100 μg/mL (TA) or 100 μM (5, 11, and 16). Accordingly, TA, 5, 11, and 16, especially 11, were identified as promising candidates for further investigation into their potential use as immunosuppressive agents.