Recent Studies on Cyclic 1,7-Diarylheptanoids: Their Isolation, Structures, Biological Activities, and Chemical Synthesis

Abstract

Diarylheptanoids are a family of plant secondary metabolites with a 7 carbon skeleton possessing two phenyl rings at the 1- and 7-positions. They can be subdivided into acyclic and cyclic diarylheptanoids where the latter are further divided into meta,meta-bridged biphenyls ([7.0]metacyclophanes) and meta,para-bridged diphenyl ether heptanoids (oxa[7.1]metapara-cyclophanes). Since the isolation of curcumin from the rhizomes of turmeric (Curcuma longa) in 1815 which was named curcumin, a variety of diarylheptanoids have been isolated from a number of plant families such as Aceraceae, Actinidiaceae, Betulaceae, Burseraceae, Casuarinaceae, Juglandaceae, Leguminosae, Myricaceae, and Zingiberaceae. Earlier studies on these diarylheptanoids have been summarized on several occasions, of which the main themes only focus on isolation, structure elucidation, and the biological properties of linear types. Only a few have covered cyclic diarylheptanoids and their chemical synthesis has been covered lastly by Zhu et al. in 2000. The present paper has, therefore, covered recent progress in cyclic diarylheptanoids focusing on the isolation, structural and biological features, and chemical synthesis.

New Cyclic Diarylheptanoids from Platycarya strobilacea

“…In the 1 H-NMR spectrum, six aromatic proton signals at δ H 6.57 (dd, J = 8.1, 2.1 Hz, H-6′), 5.72 (d, J = 2.1 Hz, H-2′), 6.72 (d, J = 8.1 Hz, H-5′), 6.82 (d, J = 2.0 Hz, H-2″), 6.77 (dd, J = 8.2, 2.0 Hz, H-6″), and 6.83 (d, J = 8.2 Hz, H-5″) revealed the presence of two 1,3,4-trisubstituted aromatic rings that were ABX coupling patterns. The chemical shift of H-2′ at 5.72 ppm appeared highly upfield from other aromatic proton signals, and such a shielding effect is characteristic of biaryl-type cyclic diarylheptanoids that have an ether linkage between C-3′ and C-4″ [ 2 , 8 , 11 ]. The above information suggests that compound 1 is 2-hydroxy-3′,4″-epoxy-1-(4′-hydroxyphenyl)-7-(3″-hydroxyphenyl)-3-heptanone.…”

“…Therefore, the structure of compound 5 was proposed and named platycary E. Previously, Jahng and Park (2018) summarized series of cyclic diaryl ether heptanoids and their biological properties. Some of these compounds showed cytotoxic activities against human cancer cell lines, nitric oxide (NO) production inhibitory activity, neuroprotective activity, radical scavenging activity, and osteogenic activity [2]. In view of the valuable pharmacological activities of cyclic diarylheptanoids, we tested the cytotoxic activity of compounds 1-5 against human cancer cell lines (including HL-60, A549, SMMC-7721, MCF-7, and SW480), and their ability to inhibit NO production in Lipopolysaccharide (LPS) activated murine macrophage RAW 264.7 cells and protective effect of corticosterone-induced apoptosis in Pheochromocytoma (PC12) cells.…”

“…More than 500 diarylheptanoids, an important class of plant secondary metabolites with a aryl-C7-aryl skeleton (linear or cyclic type), have been isolated from a number of plant families, including the Aceraceae, Actinidiaceae, Betulaceae, Burseraceae, Casuarinaceae, Zingiberaceae Leguminosae, Myricaceae, and Juglandaceae [ 1 ]. Cyclic diarylheptanoids are further divided into meta , meta -bridged biphenyls and meta , para -bridged diphenyl ether heptanoids, many of which have beneficial biological activities such as anti-tumor, anti-inflammatory, estrogenic, anti-amyloidogenic, and anti-emetic activity [ 1 , 2 ]. Hence, the discovery of new natural diarylheptanoids and their phytochemical characterization is of considerable potential benefit to medical science.…”

Diarylheptanoid analogues from the rhizomes ofZingiber officinaleand their anti-tumour activity

“…R9 was treated by semi-preparative HPLC eluting with 42% CH 3 CN, and compound 8 (11.6 mg, t R ¼ 25.6 min) was obtained. In addition, detailed isolation procedures for known compounds (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) and spectroscopic data of isolated new compounds are provided in the ESI. †…”

Stable Catechol Keto Tautomers in Cytotoxic Heterodimeric Cyclic Diarylheptanoids from the Seagrass Zostera marina

“…Due to their inherent steric strain, cyclic diarylheptanoids are frequently found to possess axial and/or planar chirality. 2 , 3 Indeed, the smallest natural product that contains axial, planar, and point chirality elements in the same molecule is the cyclic diarylheptanoid tedarene B. 4 When the energy barrier between the atropisomers is relatively low, axial or planar chirality is known to cause coalescent NMR signals.…”