lignans and tetralin

(-)-Podophyllotoxin is one of the most potent microtubule depolymerizing agents and has served as an important lead compound in antineoplastic drug discovery. Reported here is a short chemoenzymatic total synthesis of (-)-podophyllotoxin and related aryltetralin lignans. Vital to this approach is the use of an enzymatic oxidative C-C coupling reaction to construct the tetracyclic core of the natural product in a diastereoselective fashion. This strategy allows gram-scale access to (-)-deoxypodophyllotoxin and is readily adaptable to the preparation of related aryltetralin lignans.

Topics: Antineoplastic Agents, Phytogenic; Biological Products; Dioxygenases; Humans; Lignans; Molecular Structure; Podophyllotoxin; Tetrahydronaphthalenes

Eight new aryltetralin lignans, cleisindosides A-F (1-6), picroburseranin (7), and 7-hydroxypicropolygamain (8), were isolated from the fruits of Cleistanthus indochinensis (Euphorbiaceae). The structures of the isolates were established on the basis of their one- and two-dimensional NMR spectral data, as well as their mass spectrometric data. Compound 7 was found to have potent cytotoxicity against oral epidermoid carcinoma cells with an IC50 value of 0.062 µM, whereas glycosylation to 3 (IC50 7.5 µM) and stereochemical changes to 8 (IC50 10.8 µM) led to marked decreases in biological activity. Thus, it was determined that the C-7 and C-8' positions are critical for the biological activity of the lignans from this plant.

Topics: Antineoplastic Agents, Phytogenic; Cell Line, Tumor; Cell Survival; Chromatography, High Pressure Liquid; Euphorbiaceae; Fruit; Glycosides; Humans; Inhibitory Concentration 50; Lignans; Magnetic Resonance Spectroscopy; Molecular Structure; Plant Extracts; Tetrahydronaphthalenes

Phytochemical investigation of the aerial parts of Eriope blanchetii and E. latifolia (Lamiaceae) yielded podophyllotoxin, as well as the aryltetralin lignans α- and β-peltatin and yatein. Oleanolic, ursolic and epikatonic acids were also isolated. This is the first occurrence of podophyllotoxin in the family.

Topics: Chromatography, Thin Layer; Lamiaceae; Lignans; Magnetic Resonance Spectroscopy; Podophyllotoxin; Spectrometry, Mass, Electrospray Ionization; Tetrahydronaphthalenes

The aryl tetralin lignans are synthesized by Podophyllum sps. and are in great demand worldwide due to their use in synthesis of topoisomerase inhibitors. However, the sustained production of these aryl tetralin lignans requires large-scale harvesting from the natural environments, which has resulted in the plant-endangered status. In view of the difficulties in their total chemical synthesis, cultivation and failure of metabolic engineering approaches, there is a need to search for alternative sources of production of aryl tetralin lignans. We unequivocally established the methodology for isolation, identification, and characterization of a novel fungal endophyte (Trametes hirsuta) that produces aryl tetralin lignans consistently as shown by HPLC, LC-MS, LC/MS-MS and (1)H NMR. The lignans produced by the microorganism are biologically active, and exhibit potent antioxidant, anticancer and radioprotective properties. This strategy promises to improve the production of these therapeutically important compounds at lower costs.

Topics: Cell Fractionation; Chromatography, High Pressure Liquid; Fungi; Kinetics; Lignans; Lipid Peroxidation; Models, Biological; Plant Cells; Plant Structures; Plants; Podophyllotoxin; Podophyllum; Spectrometry, Mass, Electrospray Ionization; Tetrahydronaphthalenes

The conformational properties of polygamain and morelensin, two aryltetralin lignan lactones, have been investigated in both the gas-phase and chloroform solution using DFT calculations at the B3LYP/6-311G(d,p) level. Results indicate that the conformation of polygamain is very rigid. Thus, the conformational flexibility of its five-membered rings is considerably restricted as reflects the pseudorotational parameters of the corresponding envelope conformations. On the other hand, morelensin shows a notable conformational flexibility, which is mainly due to its two methoxy groups. Accordingly, 16 minimum energy conformations with relative energies smaller than 2.4 kcal/mol were detected. Furthermore, chemical shifts for 13C nuclei have been calculated using the GIAO method, results being compared with experimental data. A good agreement was found for both polygamain and morelensin.

Topics: Benzofurans; Dioxoles; Lactones; Lignans; Models, Chemical; Models, Molecular; Molecular Conformation; Tetrahydronaphthalenes