Indole Alkaloids from Cephalanceropsis gracilis

Abstract

Purification of CHCl3 and EtOAc solubles of the MeOH extract of Cephalanceropsis gracilis afforded seven new indole alkaloids, cephalinones A (1), B (2), C (3), and D (4) and cephalandoles A (5), B (6), and C (7), besides eight known compounds. The structures of the new compounds were determined by spectroscopic analysis. All 15 indole alkaloids were evaluated for their cytotoxic effects on MCF-7, NCI-H460, and SF-268 cell lines by the MTT method. Only cephalinone-F (6) showed significant cytotoxicity.

Structural Revisions of Natural Products with the Aid of the Structure Elucidator System

“…Cephalandole A was clearly a closely related structure with the same elemental composition as 12.16, and structure 12.17 was hypothesized as the most likely candidate. Compound 12.17 was described in the mid 1960s and this structure was synthesized by Mason et al 30 The spectral data of the reaction product fully coincided with those reported by Wu et al 29 The true chemical shift assignment is shown in structure 12.17. For clarity the differences between the original and revised structures are shown in Figure 12.…”

“…The synthetic compound displayed significantly different data from those given by Wu et al 29 The 13 C chemical shifts of the synthetic compound are shown on structure 12.16A. Cephalandole A was clearly a closely related structure with the same elemental composition as 12.16, and structure 12.17 was hypothesized as the most likely candidate.…”

“…In 2006 Wu et al 29 isolated a new series of alkaloids, particularly cephalandole A, 12.16. Using 2D NMR data (not tabulated in the article) they performed a full 13 C NMR chemical shift assignment as shown on structure 12.16.…”

Single-molecule chemistry and physics explored by low-temperature scanning probe microscopy

“…88 All these features are present in a metabolite of the pressuretolerant actinobacterium Dermacoccus abyssi, which was isolated from the sediment collected from the deepest place on Earth, Challenger Deep in the Mariana Trench. 89 Using SPM in addition to NMR and MS, the molecule could be identified as cephalandole A, 80 a molecule that was originally found in a Taiwanese orchid and that was first misassigned 90 and later corrected. 91 To identify the molecule from the deep sea bacterium, first its chemical formula was quickly determined to be C 16 H 10 N 2 O 2 by high-resolution MS. Then state of the art NMR spectroscopy was carried out to determine the substructures (shown in Fig.…”

“…Structures 3 and 4 could already be ruled out, because the angle between the two bicyclic systems could not be brought into accordance with the AFM measurements. This left only structure 1, cephalandole A, and structure 2, the previously misassigned structure of cephalandole A, 90 as candidates. Finally, the determination of the adsorption site by SPM and comparison with DFT calculations ruled out structure 2 and unambiguously identified the molecule as structure 1, i.e.…”