Two new C-benzylated chalcones and one new mimosin-type homoisoflavonoid from the twigs and leaves of Caesalpinia digyna.

Two new C-benzylated chalcones, 2',4'-dihydroxy-3'-(2-hydroxylbenzyl) chalcone (1) and 2',4'-dihydroxy-5'-(2-hydroxybenzyl) chalcone (2), one new and one known mimosin-type homoisoflavonoid, mimosol H (7) and mimosol G (8), together with four known chalcones (3-6) and four known sappanin-type homoisoflavonoids (9-12), were isolated from the twigs and leaves of Caesalpinia digyna. Their structures were characterized by comprehensive spectroscopic analyses (including NMR and HRESIMS). Compounds 1, 2 and 8 exhibited moderate cytotoxicity against SMMC-7721, A-549 and/or MDA-MB-231 cell lines with IC50 values ranging from 11.41 ± 0.88 to 30.01 ± 1.56 µM. Notably, C-benzyl chalcones (1 and 2) were isolated from species of the genus Caesalpinia for the first time. Homoisoflavonoids 7 and 8 are the first examples of mimosin-type homoisoflavonoids reported in Caesalpinia digyna.

Alkaloids from the stem barks of Erythrina stricta.

Four previously undescribed erythrinan alkaloids, 8α-acetonylerythristemine, 8α-acetonylerysotrine, 10ß-hydroxy-11ß-methoxyerysotramidine and 3-epierysotrine, one undescribed pyrrolidine derivative, S-1-(4-hydroxy-3-methoxyphenethyl)-5-hydroxy pyrrolidin-2-one, and one undescribed amide, N-(3-hydroxy-4-methoxyphenethyl)-4-hydroxylbutanamide, along with thirteen known alkaloids were isolated from the stem barks of Erythrina strica Roxb. (Leguminosae). Their structures were identified by extensive analysis of physical, spectroscopic and spectrometric data. It's very interesting that the coexistence of 3-methoxytyramine, erythrinarbine, S-1-(4-hydroxy-3-methoxyphenethyl)-5-hydroxy pyrrolidin-2-one and N-(3-hydroxy-4-methoxyphenethyl)-4-hydroxylbutanamide that may be closely related in biosynthesis, supports the hypothetical biogenetic pathway of pyrrolo [2,1-a]isoquinoline alkaloids.