Four Cyclopeptide Alkaloids from Discaria longispina

Abstract

The isolation of the cyclopeptide alkaloids, adoutine-Y', discarine-B, discarine-E, and discarine-X, a new 14-membered cyclopeptide alkaloid from D. longispina, are reported. The structure of the new alkaloid was elucidated by spectroscopic methods and by chemical degradation.

Plant Cyclopeptides

“…The following reagents or methods were used to detect cyclopeptide alkaloids nonspecifically: a fluorescent indicator, ,,, 10% or 30% aqueous sulfuric acid, ,, vanillin−sulfuric acid reagent, anisaldehyde−H 2 SO 4 reagent, diazo reagent, cerium(IV) reagent, Mayer's reagent, and Dragendorff's reagent; ,,,,,,− ,− ,,,,,, Dragendorff's reagent was the most common one.…”

Stereochemistry and NMR Data Assignment of Cyclopeptide Alkaloids from Zizyphus Oxyphylla

“…533.1763). The EI-MS spectrum showed a base peak at m/z 148, which indicated the presence of N, N-dimethyl phenylalanine as a side chain [4]. In the 1 H NMR spectrum, a 6H methyl singlet at δ 2.38 was assigned to N, N-dimethyl protons.…”

“…Figure 3: Key HMBC interactions in compounds 1-3. formula of C 31 H 40 N 4 O 5 (calcd for C 31 H 40 N 4 O 5 + H = 549.3076). The EI-MS showed a base peak at m/z 148, which indicated the presence of N, N-dimethyl phenylalanine as a side chain[4]. When the NMR spectroscopic data of 2 were compared with those of 1, the resonances for proline (A) were found to be missing, showing instead a leucine amino acid unit (Table1).…”

Naturally-Occurring Cyclopeptides: Structures and Bioactivity

“…Discaria americana (bark) Discarene C [186] Discarene D [186] (root bark) Adouetine Y' [187] Franganine [187] Frangulanine [187] Discarines A, B, C, D, M, N [187] Discaria longispina Adoutine Y' [188] Discarine B [188] Discarine E [188] Discarine X [188] Discaria febrifuga Discarine G [189] (bark) Frangufoline [190] Adouetine [190] Scutianine B [190] Franganine [190] Discarines C and D [190] Zizyphus amphibia (bark) Amphibine A (41) [125] Amphibine B [125] Amphibine C [125] Zizyphus oenoplia (bark) Zizyphine A (9) [191,192] Zizyphine B (29) [191,192] Zizyphine C (30) [191,192] Zizyphine D (51) [191,192] …”