Suadimins A–C, Unprecedented Dimeric Quinoline Alkaloids with Antimycobacterial Activity from Melodinus suaveolens

Abstract

The suadimins A–C (1–3) from Melodinus suaveolens are the first example of monoterpenoid quinoline alkaloid dimers featuring an unprecedented carbon skeleton. Their structures and absolute configurations were established on the basis of extensive spectroscopic analyses, electric circular dichroism (ECD), and X-ray crystallography. Suadimin A showed significant antimycobacterial activity in vitro with an MIC90 of 6.76 μM against the H37Rv strain of M. tuberculosis.

Discovery of four modified classes of triterpenoids delineated a metabolic cascade: compound characterization and biomimetic synthesis

“…1,2 Cascade reactions based on biosynthetic mechanism have been recognized as a crucial synthetic strategy enabling consecutive chemical transformations. [3][4][5][6][7] In addition to discovering structurally interesting and biologically significant natural molecules, [8][9][10][11][12][13][14][15] we have been committed to the biomimetic and/or bioinspired syntheses of important natural compounds identified by our research group as well, which aimed to validate the proposed biosynthetic pathways from chemical view. [16][17][18][19] Dichapetalin-type triterpenoids, a rare category of natural products featuring the modified skeletons by condensing a C6-C2 unit to the A ring of 13,30-cycodammarane triterpenoids, were found as the characteristic components of Dichapetalum and Phyllanthus genera.…”

Suadimins D—J, Monoterpenoid Indole‐Quinoline and Bisindole Alkaloids from Melodinus suaveolens

“…The family Apocynaceae contains about 250 genera and 2000 species of tropical trees, shrubs, woody climbers, and herbs, [ 6 ] which is one of the major plant family of MIAs, MQAs, and their conjugates. [ 2,7 ] To date, about 170 monoterpenoid bisindole, bisquinoline, and indole‐quinoline alkaloids consisting of more than 15 kinds of MIAs and MQAs monomeric blocks, with either single linkages (such as C‐3/C‐10, C‐5/C‐10, C‐3/C‐14, C‐9/C‐16, C‐10/C‐16, etc .) or double linkages (such as C‐3/C‐10 and C‐14/O/C‐11, C‐22/C‐16 and N‐1, C‐16/C‐15 and N‐1/C‐3, C‐3/C‐14 and C‐5/O/C‐15, etc .…”

Clerodenoids A—F: C‐ring Aromatized and/or Rearranged Abietane Diterpenoids from Clerodendrum chinense var. simplex

“…simplex , an ethnomedicinal plant of the Dai minority in China, has been used for the treatment of rheumatic arthritis, hypertension, erysipelas, and chronic osteomyelitis. [ 12 ] As part of our continuing efforts toward the discovery of biologically active diterpenoids from medicinal plants, [ 13‐18 ] six new diterpenoids ( 1 — 6 , Figure 1) were identified from the roots of C. chinense . Their structures were elucidated by extensive spectroscopic data analysis and X‐ray crystallography, as well as time‐dependent density functional theory‐based electronic circular dichroism (TDDFT‐ECD) calculation.…”