Henrycinols A and B, Two Novel Indole Alkaloids Isolated from Melodinus henryiCraib

Abstract

(5), were isolated from the roots of Melodinus henryi Craib. Their structures were established on the basis of 1D-and 2D-NMR spectroscopic analysis. The relative configuration of henrycinols A and B was determined by NOESY analysis.

Application of the Asymmetric Pictet–Spengler Reaction in the Total Synthesis of Natural Products and Relevant Biologically Active Compounds

“…Henrycinols A and B, two indole alkaloids, extracted from Melodinus henryi CRAIB of Apocynaceae genus by Zhang and co-workers [ 149 ]. These alkaloids belong to the class of 1,2,3,4-tetrahydro-β-carbolines, a structural scaffold, that is, abundant in a range of indole alkaloids [ 150 ].…”

“…The natural products henrycinol A and B were obtained in satisfactory overall yield in eight and nine steps, respectively. Therefore, the synthetic sequence starting with the PSR of the desired aldehyde [ 151 , 152 ] obtained from (−)-2,3- O -isopropylidene- d -threitol 66 with l -tryptophan methylester 67 gave a separable mixture of 1,3- cis tetrahydro-β-carboline 69α as the main product in 50% yield and 1,3- trans tetrahydro-β-carboline 69β in 18% yield [ 149 ].…”

Phytochemical and Pharmacological Properties of the Genus Melodinus – A Review

“…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]. Five indole alkaloids, Δ14-vincamenine N4-oxide (99), meloyunine (109), 14β-hydroxymeloyunine (110) and its epimer (111), and 16,19-epoxy-Δ14-vincanol (113) were described from M. yunnanensis [32].…”

“…Three other novel alkaloids, melohenine A (163), an unusual C24 monoterpenoid indole alkaloid with additional skeletal carbons arranged compactly in eight rings, and henrycinols A-B (164-165) with an a cinnamoyl group system were also isolated from roots of M. henryi [52,57]. The relative configuration of henrycinols A and B was determined by NOESY analysis.…”

“…(3α,14α,16α)-2,7-secoeburnamine derivative (207) with an unprecedented 6/9/6/6 tetracyclic ring system, regarded as a key intermediate from indole to quinoline alkaloids were obtained from M. henryi and M. yunnanensis [35,52,55]. Three simple alkaloids, venoterpine (208), ( )-R/S-1-(3-pyridyl)ethanol (209) and 2, 5-diphenyloxazole (210), were also isolated from M. aeneus, M. axillaris and M. celastroides [33,38,45].…”