Melodinines A−G, Monoterpenoid Indole Alkaloids from Melodinus henryi

Abstract

Nineteen monoterpenoid indole alkaloids including seven new ones, melodinines A-G (1-7), were isolated from Melodinus henryi. The structures of the new compounds were elucidated using spectroscopic methods, and the structure of compound 4 was confirmed by single-crystal X-ray diffraction analysis. The known compounds were identified by comparing their spectroscopic data with those reported in the literature. All of the compounds were evaluated for cytotoxic activity against five human cancer cell lines, and compound 11 exhibited cytotoxicity against HL-60, SMMC-7721, A-549, and SK-BR-3 cells with IC50 values of 2.0, 16.8, 25.9, and 24.7 microM, respectively.

Phytochemical and Pharmacological Properties of the Genus Melodinus – A Review

“…Fig 6) Five pair of epimers, 87-96, were isolated from nine Melodinus species. Four eburnamine-type alkaloids including two new ones, melodinines F-G (97, 98), together with O-methylepivincanol (100), (-)-eburnamenine (101) were isolated from M. henryi [35,48]. Δ14-Isoeburnamine (105) and (+)-isoeburnamine (106) were obtained from M. celastroides, M. henryi, M. oblongus and M. henryi [30,40,42,52].…”

“…(Table 5( Melodinines A-C (158-160, resp. ), together with leuconotis alkaloid 376 (161), possessed 22 skeletal carbons arranged compactly in six rings, were isolated from M. henryi by RP-18 gel and Sephadex LH-20 [48].…”

“…Two known compounds, stemmadenine (166) and its N-oxide (167), were isolated from M. henryi [18,35,48]. [38].…”

“…Other monomeric alkaloids, 204-210 ( Figure 13) (-)-Rhazinilam (204) was a natural compound isolated from M. australis and M. henryi, whose tetracyclic structure possesses an axially chiral phenyl-pyrrole subunit bridged by a ninemembered lactam ring [18,35,48,68]. Melohenine B (205), 14, 15-dehydromelohenine B (206) and…”

A Photoinduced Cyclization Cascade—Total Synthesis of (−)‐Leuconoxine

“…Besides leuconoxine and its structural siblings leuconodines A-F [7] and melodinine E, [8] the fenestrane structure motif is only reported in three other natural products: laurenene, [9] the penifulvins such as penifulvin A, [10] and asperaculin A [11] -all of them are terpenes. To the best of our knowledge, the leuconoxine subgroup represent the first alkaloids containing a fenestrane structure motif.…”