Abstract:

2D NMR techniques (COSY, TOCSY, HMQC, HMQCTOCSY, HMBC, NOESY) were used to elucidate the structure of schnabepeptide, a cyclic octopeptide isolated from the whole plant of schnabelia oligophylla Hand. Mazz. (Lamiaceae). The proton-coupling network shown in the TOCSY spectrum suggests that the octopeptide contains eight amino acid residues (a L-Ser, a L-Ile, a Gly, a D-Trp, two L-Val and two Pro). The 2D NOESY and HMBC spectra show the sequential connectivity of schnabepeptide is cyclo-(NH-Trp-Val-Gly-Val-Ser-Ile-Pro-Pro-CO).

Key words: NMR, assignments, HMQC, structure, schnabelia oligophylla, cyclic octopeptide