Warifteine and methylwarifteine: ¹H and ¹³C assignments by two‐dimensional NMR spectroscopy

Abstract

The identity and structures of warifteine and methylwarifteine, two tertiary bisbenzylisoquinoline alkaloids of an unusual type, were elucidated and verified by 2D NMR spectroscopy. Complete 1 H and 13 C NMR spectral assignments were obtained.

1H and 13C NMR assignments of two new isomeric bisbenzylisoquinoline alkaloids from Cissampelos sympodialis Eichl. (Menispermaceae)

“…A similar strategy based on the well‐resolved signal for H‐5 and its long‐range HMBC correlations allowed assignments for the F ring system to be made. Additional evidence for these assignments was obtained by comparison with data for roraimine and warifteine . Similar correlations for compound 2 were observed (Table ).…”

“…The infrared spectrum was carried out in KBr disks and showed the following bands: 3480 cm À1 (hydroxyl group), 1676 cm À1 (a,b-unsaturated carbonyl), 1610 cm À1 (C = C olefinic), and 1503 cm À1 (C = C aromatic). The first noteworthy feature in the 13 C NMR spectrum of the isolated material was a pair of high-frequency signals at d C = 192.45 ppm and 192.08 ppm, which did not correspond to any of the signals attributed to warifteine, [7] but are close to the chemical shift attributed to the C-15 carbonyl of roraimine (d C = 192.4 ppm). [6] The high-resolution positive electrospray mass spectrum displayed an intense quasimolecular [M + H] + ion at m/z = 607.2459 compatible with the molecular formula C 36 H 35 N 2 O 7 (error = 3.4 ppm for calculated 607.2438).…”

“…In our continuing investigation of bioactive compounds isolated from the species C. sympodialis , we have found several pharmacologically active bisbenzylisoquinoline alkaloids in the extracts of this plant's leaves and rhizomes, including warifteine and methylwarifteine as well as roraimine . Recently, spectral assignments and reference data were published for warifteine, an unusual alkaloid containing a p ‐xylyl moiety . During a routine extraction procedure aimed at isolating of warifteine, the major bisbenzylisoquinoline alkaloid found in the rhizomes of C. sympodialis , two new diastereomeric alkaloids were found as a mixture.…”

“…[6] Recently, spectral assignments and reference data were published for warifteine, an unusual alkaloid containing a p-xylyl moiety. [7] During a routine extraction procedure aimed at isolating of warifteine, the major bisbenzylisoquinoline alkaloid found in the rhizomes of C. sympodialis, two new diastereomeric alkaloids were found as a mixture. These alkaloids were found to be structurally related to roraimine, a bisbenzylisoquinoline alkaloid previously isolated from the rhizomes of C. sympodialis.…”

Strychnos L. da América do Sul e Central

“…A maioria das espécies usadas popularmente emprega o chá das folhas ou cascas (Angenot et al, 1990b;Frederich et al, 2000) (Mukherjee et al, 2003), (Tabela 1). Segundo Verpoorte (1977), os alcalóides indólicos monoterpênicos são subdivididos em 3 séries em função da substituição no C 3 : a série normal apresenta um hidrogênio no C 3 , como por exemplo a estricnina (20); a série pseudo apresenta uma hidroxila no C 3 , como a 3-hidroxidiabolina (19b) e a série N-metil-seco-pseudo apresenta uma carbonila no C 3 e o nitrogênio apresentase substituído, geralmente com um grupamento metila, como a 10,11-dimetoxiestricnobrasilina (34b).…”