Regioselective Acylation of Ginsenosides by Novozyme 435 to Generate Molecular Diversity

Abstract

Ginsenosides are major bioactive constituents of ginseng (Panax spp.; Araliaceae), a traditional Chinese medicinal herb. In order to increase the molecular diversity and broaden the potential usage of ginsenosides, ginsenosides Rd (1), Rg3 (2), (20R)‐Rg3 (3), Rh2 (4), Re (5), Rh1 (8), Rg2 (9), gypenoside XVII (6), and pseudoginsenoside F11 (7) were regioselectively acylated with vinyl acetate, catalyzed by Novozyme 435 (lipase B from Candida antarctica), in organic solvents to afford different mono‐acetyl ginsenosides. Ginsenoside Rd (1) was also acylated with vinyl decanoate or vinyl cinnamate to generate 1b and 1c, respectively. Acylation of glucosylated ginsenosides (1–4, 6, 8) occurred at the primary 6‐OH function of the terminal glucose (Glc) moiety of the sugar at C(3) or C(20) of the dammarane‐type aglycone. In contrast, ginsenosides 5, 7, and 9, containing mixed sugar moieties, resulted in acylation of both the rhamnose (Rha) and the glucose (Glc) moieties. In the case of ginsenoside Re (5) and pseudoginsenoside F11 (7), acylation at the secondary 4‐OH function of the terminal Rha moiety, attached at C(3) of the aglycone, is preferred. The structures of all acylated products were determined by extensive MALDI‐TOF‐MS and NMR analyses.

Triterpenoids with Promoting Effects on the Differentiation of PC12 Cells from the Steamed Roots of Panax notoginseng

“…The other 30 carbons (Table 2) were assigned to nine methines with three oxygen-bearing (δ C 89.0, 71.0, and 80.1) and two olefinic (δ C 136.1 and 130.3) methines, eight methyls, seven methylenes, and six quaternary carbons, of which two are The absolute configuration of the side chain in 1 was determined from the 1 H NMR coupling constants, the 13 C NMR chemical shifts, and analysis of the Mo 2 (AcO) 4 -induced circular dichroism data. The large coupling constant of J 22,23 (15.6 Hz) suggested the E-geometry of Δ 22,23 20 The absolute configuration of C-24 was determined using Mo 2 (AcO) 4induced circular dichroism. The aglycone 1a was mixed with Mo 2 (AcO) 4 in DMSO to give a metal complex, which displayed a positive Cotton effect at 296 nm (Figure 1), suggesting the 24S configuration for 1a, according to the Snatzke rule.…”

“…The large coupling constant of J 22,23 (15.6 Hz) suggested the E-geometry of Δ 22,23 . The deshielded chemical shifts of C-21 (δ C 28.8) and C-17 (δ C 53.7) indicated the 20S configuration in 1, compared to a 20R configuration [C-21 (δ C 22.8) and C-17 (δ C 50.7)].…”

New Dammarane‐Type Saponins from the Rhizomes of Panax japonicus

“…The isolation of many acylated glycosides from the title plant further confirmed this assumption [27] [28]. The assignment of the 13 C-NMR data of C(1') and C(1'') in 6'''-O-acetylginsenoside Re [24] was revised. Assay for Determining whether 3 Was an Artifact or Natural Product.…”

“…In addition, the HMBC correlation of d(H) 5.02 (Glc HÀC(1')) with d(C) 79.6 (aglycone C(6)) was also observed. The ROESY correlations between HÀC(27) and HÀC (24) established the configuration of the C(24)¼C(25) bond as (Z). Accordingly, the structure of 2 was elucidated as shown in Fig.…”

“…Previously, Teng et al had obtained this compound by the acylation of ginsenoside Re, which was catalyzed by Novozyme 435 using vinyl acetate as the acyl donor [24]. Tung et al also isolated it from the flower-buds of P. ginseng steamed at 1208 for 4 h under 0.15 MPa pressure [25].…”