Lignans and Neolignans from Sinocalamus affinis and Their Absolute Configurations

Abstract

Twenty-two new lignans and neolignans (1-22), together with 14 known analogues, have been isolated from an ethanolic extract of the stem (with skin removed) of Sinocalamus affinis. Their structures were elucidated by spectroscopic and chemical methods. On the basis of systematic NMR and circular dichroism (CD) data analysis, the validity of J7,8 and ΔδC8-C7 values to distinguish threo and erythro aryl glycerol units in different neolignans and the CD data [particularly the Rh2(OCOCF3)4-induced CD data (the E band)] to determine the absolute configurations at C-8 (C-7) of the aryl glycerol units are discussed. At a concentration of 10 μM, compounds 20 and 22 inhibited NO production in mouse peritoneal macrophages 84.2±5.9% and 71.7±1.0%, respectively. Compounds 19, 20, and 22 showed activity against serum deprivation induced PC12 cell damage by increasing the cell viability from 80.7±2.8% to 91.6±6.4%, 107.2±8.0%, and 97.6±8.5%, respectively.

(±)-Acortatarinowins A–F, Norlignan, Neolignan, and Lignan Enantiomers from Acorus tatarinowii

“…These compounds showed typical antipodal ECD curves ( Figure 2b) and specific rotations of opposite sign. The positive Cotton effect around 233 nm in the ECD spectrum suggested an 8S configuration for (−)-2a, 9,12 allowing the determination of the absolute configuration of (−)-2a as 7R,8S and that of its enantiomer (+)-2b as 7S,8R. Compounds 2a and 2b were assigned the names (−)-acortatarinowin B and (+)-acortatarinowin B, respectively.…”

Two new glycosides and one new neolignan from the roots of Cynanchum stauntonii

“…Analysis of the 13 C NMR and DEPT spectra (Section 2) showed resonances for twentytwo carbons: seven aromatic quaternary carbons (including four oxygenated ones), nine methines (including five aromatic and two olefinic ones), three oxygenated methylenes, and three methyls (including two methoxyls). The proton and carbon signals in the 1 H and 13 CNMR spectra of 3 were superimposable on those of (+)-(7S, 8R, 7 0 E)-4-hydroxy-3, 5 0 -dimethoxy-4 0 , 7-epoxy-8, 3 0 -neolign-7 0 -ene-9, 9 0 -diol 9 0 -ethyl ether, a known neolignan isolated previously from Sinocalamus affinis (Xiong et al, 2011), except that the hydroxyl group of 3 was proposed to be linked at C-5 instead of C-4, which was supported by the long-range 1 H-13 C correlations from d H 6.89 (H-2) to d C 115.3 (C-4), 118.5 (C-6), 87.3 (C-7); d H 6.96 (H-4) to d C 110.2 (C-2), 118.5 (C-6); d H 6.74 (H-6) to d C 110.2 (C-2), 115.3 (C-4), 87.3 (C-7) in the HMBC spectrum (Fig. 2).…”

“…2). In addition, the absolute configurations of C-7 and C-8 were established by analysis of the CD spectrum of 3, which displayed a typical Cotton effect, positive at 230 nm and negative at 258 nm and 283 nm, suggesting compound 3 had the 7S and 8R configurations (Xiong et al, 2011). On the basis of the evidences above, compound 3 was concluded to be (+)-(7S, 8R, 7 0 E)-5-hydroxy-3, 5 0 -dimethoxy-4 0 , 7-epoxy-8, 3 0 -neolign-7 0 -ene-9, 9 0 -diol 9 0 -ethyl ether.…”

Antioxidant compounds from ethanol extracts of bamboo (Neosinocalamus affinis) leaves

“…In addition to the coupling constant of anomeric proton (J ¼ 7.6 Hz), the detection of glucose in acid hydrolysis products of compound 9 on TLC (EtOAcMeOH -H 2 O, 15:6:2, v/v/v) indicated the presence of glucopyranosyl unit with b-D or a-L configuration in compound 9. 8 00 -guaiacylglyceryl) ether [7], and [9]. On biogenetic basis, it is reasonable for compound 9 to possess such absolute configurations by comparing with 1, and aglycone derivatives isolated from the same species [7].…”

“…8 00 -guaiacylglyceryl) ether [7], and [9]. On biogenetic basis, it is reasonable for compound 9 to possess such absolute configurations by comparing with 1, and aglycone derivatives isolated from the same species [7]. Thus, the structure of compound 9 was determined as…”