Nitrogen-containing bibenzyls from Pleione bulbocodioides: Absolute configurations and biological activities

Dihydrophenanthrene Dimers: Why and Where It Is Possible to Isolate Their Precursors

An interesting class of compounds of natural origin is dihydrophenanthrene dimers, which are characterized by a series of remarkable biological properties. Considering the hypothesis that each dimer is obtained through a biosynthetic mechanism that involves the coupling of the corresponding radicals of the single dihydrophenanthrene unit, we identified 29 dihydrophenanthrenes. Of these dihydrophenanthrenes, 11 were new compounds that could be isolated from 10 different plant species; 11 had already been identified, but not yet isolated in the 17 different plant species from which the corresponding dimers had been isolated; and 7 were known and had been isolated in the same plant sources of the corresponding dimers. A targeted analysis of several natural extracts from specific plant sources would allow the identification of known or new molecules with potential and/or specific biological activities and, in a final analysis, would confirm the relative biosynthetic mechanism.

Xylochemical Synthesis and Biological Evaluation of the Orchidaceous Natural Products Isoarundinin I, Bleochrin F, Blestanol K, and Pleionol

The first total syntheses of the orchid-derived natural products isoarundinin I (1), (±)-bleochrin F ((±)-2), (±)-blestanol K ((±)-3), and (±)-pleionol ((±)-4) from renewable starting materials are reported, along with the evaluation of their biological activities. The total syntheses were based on regioselective aromatic bromination reactions in combination with a key acid-promoted regioselective intramolecular cyclization. The biological results suggest that isoarundinin I (1), (±)-blestanol K ((±)-3), and (±)-pleionol ((±)-4) have the potential to inhibit the growth of both sensitive and multidrug-resistant cancer cells.

Discovery of glucosyloxybenzyl 2-hydroxy-2-isobutylsuccinates with anti-inflammatory activities from Pleione grandiflora

Six new glucosyloxybenzyl 2-hydroxy-2-isobutylsuccinates, pleionesides A-F (1-6), along with two known compounds (7, 8) were obtained from the pseudobulbs of Pleione grandiflora (Rolfe) Rolfe. The structures and absolute configurations of new compounds were established by HRESIMS and NMR data, along with acidic hydrolysis and alkaline hydrolysis experiments. Compounds 1-6 were tested for their anti-inflammatory activities on LPS-induced BV2 microglial cells. Amoung them, 2, 4 and 5 showed moderate activities with IC₅₀ values of 73.4, 32.8 and 57.1 μM, respectively, compared with the positive control quercetin with an IC₅₀ value of 28.3 μM.

Hepatoprotective Glucosyloxybenzyl 2-Hydroxy-2-isobutylsuccinates from Pleione yunnanensis

Nine new glucosyloxybenzyl 2-hydroxy-2-isobutylsuccinates, pleionosides M-U (1-9), and 12 known compounds (10-21) were isolated from the pseudobulbs of Pleione yunnanensis. Their structures and absolute configurations were established through a combination of HRESIMS and NMR data and supported by physical and chemical methods. Compounds 5, 6, 10, and 15 showed significant in vitro hepatoprotective activity against d-galactosamine (d-GalN)-induced toxicity in HL-7702 cells with increasing cell viability by 27%, 22%, 19%, and 31% compared to the model group (cf. bicyclol, 14%) at 10 μM, respectively. Compounds 4, 9, and 11 exhibited moderate hepatoprotective activity against N-acetyl-p-aminophenol (APAP)-induced toxicity in HepG2 cells with increasing cell viability by 9%, 16%, and 12% compared to the model group (cf. bicyclol, 9%) at 10 μM, respectively.

Two new phenylpropanoid glycosidic compounds from the pseudobulbs of Pleione bulbocodioides and their hepatoprotective activity

Two new phenylpropanoid glycosidic compounds (a pair of epimers), named pleionosides K (1) and L (2), were isolated from the pseudobulbs of Pleione bulbocodioides (Franch.) Rolfe. Their structures, including absolute configurations, were elucidated by a combination of MS, NMR data, chemical methods and the comparison of experimental and calculated electronic circular dichroism (ECD). Their possible biosynthetic pathway was discussed in the text. Furthermore, the two compounds exhibited moderate hepatoprotective activity against N-acetyl-p-aminophenol (APAP)-induced HepG2 cell damage in in vitro assays, with cell survival rates of 25.83% and 28.82% at 10 μM, respectively, and antioxidant effect against H₂O₂-induced toxicity in human SK-N-SH cell, with increasing viability at 10 μM of 24.9% and 34.6%, respectively.

Chemical Constituents and Biological Activity Profiles on Pleione (Orchidaceae)

Pleione (Orchidaceae) is not only famous for the ornamental value in Europe because of its special color, but also endemic in Southern Asia for its use in traditional medicine. A great deal of research about its secondary metabolites and biological activities has been done on only three of 30 species of Pleione. Up to now, 183 chemical compounds, such as phenanthrenes, bibenzyls, glucosyloxybenzyl succinate derivatives, flavonoids, lignans, terpenoids, etc., have been obtained from Pleione. These compounds have been demonstrated to play a significant role in anti-tumor, anti-neurodegenerative and anti-inflammatory biological activities and improve immunity. In order to further develop the drugs and utilize the plants, the chemical structural analysis and biological activities of Pleione are summarized in this review.

Benzophenones from Anemarrhena asphodeloides Bge. Exhibit Anticancer Activity in HepG2 Cells via the NF-κB Signaling Pathway

A chemical investigation of the fibrous roots of Anemarrhena asphodeloides Bge. led to the isolation of four benzophenones, including one new compound (1) and three known ones (2–4). Comprehensive ¹D, ²D NMR and HRESIMS data established the structures of the isolated compounds. The absolute configurations were determined by comparison of the calculated optical rotation (OR) with experimental data. All the isolates were evaluated for their cytotoxicities on hepatocellular carcinoma cell lines (HepG2 and Hep3B). Compound 1 showed strong cytotoxicity against HepG2 and Hep3B cells, with IC₅₀ values at 153.1 and 180.6 nM. Through MTT assay, flow cytometry and Western blot analysis, compound 1 demonstrated the ability to stimulate apoptosis via the NF-κB signaling pathway in HepG2 cells. These benzophenones are potential lead compounds for the development of better treatments for hepatocellular carcinoma.

Phenanthrenequinone enantiomers with cytotoxic activities from the tubers of Pleione bulbocodioides

This is a rare report of eight new phenanthrenequinones possessing a 9(10)H-phenanthren-10(9)-one structure and their marked cytotoxic activities from natural sources.

Hepatoprotective activity of glucosyloxybenzyl succinate derivatives from the pseudobulbs of Pleione bulbocodioides

Ten previously undescribed glucosyloxybenzyl succinate derivatives, pleionosides A-J, and fifteen known compounds were isolated from the pseudobulbs of Pleione bulbocodioides (Franch.) Rolfe. Their structures were elucidated by a combination of MS and NMR data, physical and chemical methods and a comparison with known compounds. Furthermore, three compounds exhibited potent hepatoprotective activity against N-acetyl-p-aminophenol (APAP)-induced HepG2 cell damage in in vitro assays, with cell survival rates of 31.89%, 31.52% and 31.97% at 10 μM. Four compounds exhibited moderate antioxidant activity with increasing viability at 10 μM of 36.1%, 45.0%, 25.5% and 20.7%.

A practical protocol for the synthesis of bibenzyls via C(sp3)–H activation of methyl arenes under metal-free conditions

A variety of bibenzyl derivatives have been synthesized with excellent atom economy via C(sp³)–H–C(sp³)–H coupling of readily available methyl arenes using K₂S₂O₈ under metal-free and environmentally benign conditions.

The therapeutic effect of Bletilla striata extracts on LPS-induced acute lung injury by regulation of inflammation and oxidation

Identification of active ingredients, and their structures, from Bletilla striata and investigation of the antioxidative and anti-inflammatory responses in vitro and in vivo.