Five furofuranone lignan glucosides from Terminalia citrina inhibit in vitro E2-enhanced breast cancer cell proliferation

A new lignan from the stem bark of Fagraea fragrans Roxb

A new lignan, named fagraeanolide (1), and 14 known compounds were isolated from the stem bark of Fagraea fragrans Roxb. Their structures were determined by spectroscopic methods. Fagraeanolide is the first identified oxofurofuran lignan from the genus Fagraea, whileβ-boswelic acid (4), gentiogenol (5), 3-(4-hydroxy-3-methoxyphenyl)-acrylic acid octacosyl ester (7) and pinoresinol (14) were isolated from this plant for the first time. The crude extract of F. fragrans was not toxic to cell lines. The isolated compounds showed no antibacterial activity.

The Genus Terminalia (Combretaceae): An Ethnopharmacological, Phytochemical and Pharmacological Review

Terminalia Linn, a genus of mostly medium or large trees in the family Combretaceae with about 250 species in the world, is distributed mainly in southern Asia, Himalayas, Madagascar, Australia, and the tropical and subtropical regions of Africa. Many species are used widely in many traditional medicinal systems, e.g., traditional Chinese medicine, Tibetan medicine, and Indian Ayurvedic medicine practices. So far, about 39 species have been phytochemically studied, which led to the identification of 368 compounds, including terpenoids, tannins, flavonoids, phenylpropanoids, simple phenolics and so on. Some of the isolates showed various bioactivities, in vitro or in vivo, such as antitumor, anti HIV-1, antifungal, antimicrobial, antimalarial, antioxidant, diarrhea and analgesic. This review covers research articles from 1934 to 2018, retrieved from SciFinder, Wikipedia, Google Scholar, Chinese Knowledge Network and Baidu Scholar by using "Terminalia" as the search term ("all fields") with no specific time frame setting for the search. Thirty-nine important medicinal and edible Terminalia species were selected and summarized on their geographical distribution, traditional uses, phytochemistry and related pharmacological activities.

Lignans and Neolignans: Plant secondary metabolites as a reservoir of biologically active substances

Lignans and neolignans are plant secondary metabolites derived from the oxidative coupling of phenylpropanoids. Biological activity of these phenolic compounds ranges from antioxidant, antitumor (terminaloside P, IC₅₀ = 10 nM), anti-inflammatory, anti-neurodegenerative (schibitubin B, IC₅₀ = 3.2 nM) and antiviral (patentiflorin A, IC₅₀ = 14-23 nM) to antimicrobial. In addition, it was observed that several members of this group, namely enterolactone and its biochemical precursors also known as phytoestrogens, possess important protective properties. Most of these lignans and neolignans are presented in reasonable amounts in one's diet and thus the protection they provide against the colon and breast cancer, to name a few, is even more important to note. Similarly, neuroprotective properties were observed (schisanwilsonin G, IC₅₀ = 3.2 nM) These structural motives also serve as an important starting point in the development of anticancer drugs. Presumably the most famous members of this family, etoposide and teniposide, synthetic derivatives of podophyllotoxin, are used in the clinical treatment of lymphocytic leukemia, certain brain tumors, and lung tumors already for nearly 20 years. This review describes 413 lignans and neolignans which have been isolated between 2016 and mid-2018 being reported in more than 300 peer-reviewed articles. It covers their source, structure elucidation, and bioactivity. Within the review, the structure-based overview of compounds as well as the bioactivity-based overview of compounds are described.

Naturally occurring furofuran lignans: structural diversity and biological activities

Furofuran lignans containing the 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane skeleton, represent one of the major subclasses of the lignan family of natural products. Furofuran lignans feature a wide variety of structures due to different substituents at aryl groups and diverse configurations at furofuran ring. Moreover, they exhibit a wide range of significant biological activities, including antioxidant, anti-inflammatory, cytotoxic, and antimicrobial activities. This review summarizes source, phytochemistry, and biological activities of 137 natural furofuran lignans isolated from 53 species in 41 genera of 27 plant families for the last 20 years, which provides a comprehensive information for further research of these furofuran lignans as potential pharmaceutical agents.

α-Keto tetrahydrofuran lignan glucosides from the Bangladeshi medicinal plant Terminalia citrina inhibit estradiol (E2) induced proliferation in cancer cells

EtOAc extract from the leaves of Terminalia citrina collected in Bangladesh were separated, and seven previously undescribed α-keto tetrahydrofuran lignan glucosides (terminalosides Q to W) were isolated and characterized. NOESY analysis of ¹H NMR spectra and ECD spectroscopic data analysis revealed the absolute stereochemistry of the tetrahydrofuran ring of the isolated constituents as being a (7S,8R,8'S)- configuration in terminalosides Q to U and a (7R,8R,8'S)- configuration in terminalosides V and W. All of the isolated compounds were evaluated for their estrogenic and anti-estrogenic properties using two types of estrogen-responsive human breast cancer cell lines (MCF-7 and T47D). Terminaloside R, which has a dioxymethylene group in its aromatic ring, inhibited 90% of estradiol-enhanced cell proliferation in T47D and MCF-7 cells at concentrations of 0.01 μM and 0.1 μM, respectively. On the other hand, terminaloside T, the analogous compound which has two oxymethyl groups in place of dioxymethylene, suppressed 90% of cell proliferation selectively in T47D cells at a concentration of 0.01 μM. However, terminaloside W, the 7R-stereoisomer of terminaloside R, only showed moderate activity.