Three new phenanthrenes from Monomeria barbata Lindl

Dihydrophenanthrenes from medicinal plants of Orchidaceae: A review

The plants of Orchidaceae are widely distributed in the world, 47 species of which have been used as folk medicines with a long history. The tubers and stems of them exhibit diverse efficacy, including clearing heat and resolving toxin, moistening lung and relieving cough and promoting blood circulation. Since dihydrophenanthrenes were responsible for the medical purposes, the characteristic skeletons, pharmacological effects and clinical applications of dihydrophenanthrenes were summarized in this review, so as to provide a theoretical basis for the comprehensive study, development and application of DPs from medicinal plants of Orchidaceae.

Isolation, Structural Elucidation, Optical Resolution, and Antineuroinflammatory Activity of Phenanthrene and 9,10-Dihydrophenanthrene Derivatives from Bletilla striata

A phytochemical investigation of the aqueous EtOH extract of Bletilla striata tubers afforded 34 phenanthrene and 9,10-dihydrophenanthrene derivatives, including four new compounds, 1-4. These compounds were identified using physicochemical analyses and various spectroscopic methods. Twelve of these compounds were resolved into their enantiomers, and the absolute configurations were determined by comparison of experimental and calculated ECD spectra. The antineuroinflammatory activities were evaluated by measuring the inhibition of nitric oxide production in lipopolysaccharide-stimulated BV-2 microglial cells. Compounds 7, 32, and 33 displayed inhibitory activities, with IC₅₀ values of 1.9, 5.0, and 1.0 μM, respectively, suggesting that they should be subjected to development as potential inhibitors of neuroinflammation.

Stilbenoids from aerial parts of Dendrobium plicatile

Chemical investigation of Dendrobium plicatile Lindl resulted in the isolation and identification of one new bibenzyl, 2-chloro-3, 4'-dihydroxy-3',5-dimethoxybibenzyl (1), as well as 15 known stilbenoids. The structures of this new compound was elucidated by extensive spectroscopic analysis, including HRESIMS, ¹H and ¹³C NMR, DEPT, HMBC, COSY, HMQC, NOESY. Compounds 2, 3 and 5 were obtained from this genus for the first time, compounds 8, 10, 13 and 14 were obtained from this plant for the first time. In addition, the new compound exhibited potent cytotoxic activities against the human breast cancer (MDA-MB231) cell line, the hepatocellular carcinoma (HepG2) cell line and the human lung carcinoma (A549) cell line, with IC₅₀ 3.41, 3.02, 2.80 μM, respectively.

Phenanthrenes: A Promising Group of Plant Secondary Metabolites

Although phenanthrenes are considered to constitute a relatively small group of natural products, discovering new phenanthrene derivatives and evaluating their prospective biological activities have become of great interest to many research groups worldwide. Based on 160 references, this review covers the phytochemistry and pharmacology of 213 naturally occurring phenanthrenes that have been isolated between 2008 and 2016. More than 40% of the 450 currently known naturally occurring phenanthrenes were identified during this period. The family Orchidaceae is the most abundant source of these compounds, although several new plant families and genera have been involved in the search for phenanthrenes. The presence of certain substituent patterns may be restricted to specific families; vinyl-substituted phenanthrenes were reported only from Juncaceae plants, and prenylated derivatives occur mainly in Euphorbiaceae species. Therefore, these compounds also can serve as chemotaxonomic markers. Almost all of the newly isolated compounds have been studied for their biological activities (e.g., potential cytotoxic, antimicrobial, anti-inflammatory, and antioxidant effects), and many of them showed multiple activities. According to the accumulated data, denbinobin, with a novel mechanism of action, has great potential as a lead compound for the development of a new anticancer agent.

Isolation and characterization of two new 2-isobutylmalates from Bletilla striata

The present study isolated 17 compounds from the tubers of Bletilla striata (Orchidaceae), using various chromatographic techniques. Their structures were identified based on their physical-chemical properties and spectroscopic analyses. Among them, two new 2-isobutylmalates, named bletimalates A (1) and B (2), together with other fifteen known compounds (3-17), were isolated and identified. Additionally, compounds 3, 4, and 8 were isolated from this plant for the first time.

Novel cytotoxic phenanthrenequinone from Odontioda Marie Noel 'Velano'

A new phenanthrenequinone, 5-hydroxy-2,3-dimethoxy-1,4-phenanthrenequinone (1), was isolated along with a known 9,10-dihydrophenanthrenequinone, ephemeranthoquinone B (2) from an MeOH extract of Odontioda Marie Noel 'Velano' through bioassay-guided fractionation. Their structures were elucidated by spectroscopic analysis, and the compounds were tested for in vitro cytotoxic activity. The compounds showed slightly higher cytotoxicity in human oral squamous cell carcinoma and leukemic cell lines as compared with human oral normal cells. The results suggest that apoptosis may not be involved in the cytotoxicity induction.