A new C21-steroidal glycoside with two known compounds were isolated from the root of Cynanchum Stauntonii. Based on the spectral analysis, including MS, 1H NMR, 13C NMR, DEPT, 1H-1H COSY, 13C-1H COSY, HMQC and HMBC, ...A new C21-steroidal glycoside with two known compounds were isolated from the root of Cynanchum Stauntonii. Based on the spectral analysis, including MS, 1H NMR, 13C NMR, DEPT, 1H-1H COSY, 13C-1H COSY, HMQC and HMBC, their chemical structures were determinated as glaucogenin-C 3-O-α-L-cymaropyranosyl-（1→ 4）-β-o-digitoxopyranosyl-（1→4）-β-D-canaropyranoside （1）, stigmasterol （2） and ursolic acid （3）.展开更多
Insignin A, a new C21-steroidal aglycone having the rare 15,16-seco pregnane skeleton was isolated from the acidic hydrolysis part of the 95% EtOH extract of Biondia insignis. It's structure was identified to be ...Insignin A, a new C21-steroidal aglycone having the rare 15,16-seco pregnane skeleton was isolated from the acidic hydrolysis part of the 95% EtOH extract of Biondia insignis. It's structure was identified to be 15R,16-epoxy-3?,14?,16?-trihydroxy-15,16-secopregn-5-ene-20-one based on the spectral data.展开更多
A new C_(21) furanoterpene. ent-untenospongin A (2), together with a known related compound. tetradehydrofurospongin-1 (1), has been isolated from the indian marine sponge Hippospongia sp. and its structure was determ...A new C_(21) furanoterpene. ent-untenospongin A (2), together with a known related compound. tetradehydrofurospongin-1 (1), has been isolated from the indian marine sponge Hippospongia sp. and its structure was determined on the basis of spectroscopic data.展开更多
Besides a series of normal C_(21) steroids from Marsdenia incisa incisa P.T.Li et Y.P.Li, it small amount of novel C_(21) steroidal glycoside (Ⅱ) had been isolated. The mild acidic hydrolysis of (Ⅱ) afforded genin-(...Besides a series of normal C_(21) steroids from Marsdenia incisa incisa P.T.Li et Y.P.Li, it small amount of novel C_(21) steroidal glycoside (Ⅱ) had been isolated. The mild acidic hydrolysis of (Ⅱ) afforded genin-(Ⅰ). By spectroscopic analyses of IR, ELMS, FDMS, ~1H NMR, ^(13)C NMR (DEPT, PRFT), ~1H-~1H COSY, ~1H-^(13)C COSY for (Ⅰ) and (Ⅱ), (Ⅰ) had been deduced as B-nor (7) -6β-formyl-pregnane-3β, 5β, 8β, 12β, 14β, 17β, 20-heptatol, named neomarinogenin; (Ⅱ) had been deduced as neomarinogenin 3-O-β-D-thevetopyranosyl-(1→-4)-β-Dcymaropyranosyl-(1→4)-β-D-cymaropyranoside, named neomarinoside. Their physical and spectral data were as follows. Neomarinogenin (Ⅰ). A colorless prism from Me_2 CO, mp 202—205℃, 〔α〕_D^(17)+28.81°(MeOH, c0.05), C_(21)H_(34)O_8 (Found: C, 60.76; H, 8.19, C_(21)H_(34)O_8, requires C, 60.87. H, 8.21％); IRv_(max)^(KBr)cm^(-1): 3450 (OH), 1700 (C=O), 1050(C-O-C); EIMS m/z: 397 (M-OH), 380 (397-OH), 379, 378 (M-2H_2O), 36; (M-3H_2O), 342 (M-4H_2O), 333,展开更多
Effects of 650℃ aging for 1—1000 h on structure and hydrogen embrittlement susceptibility (HES)of steel Cr21Ni6Mn9N have been investigated.The results show that M_(23)C_6 type carbide precipitates at grain boundarie...Effects of 650℃ aging for 1—1000 h on structure and hydrogen embrittlement susceptibility (HES)of steel Cr21Ni6Mn9N have been investigated.The results show that M_(23)C_6 type carbide precipitates at grain boundaries and Cr-depletive region appears beside them during aging.The precipitates grow and connect each other as the aging time prolongs.Meanwhile, the degree of Cr-depletion aggravates first and then recovers gradually while the aging time is very long,i.e.,1000 h.The HES of the steel increases with increasing aging time but does not reduce with the recovery of Cr content at the Cr-depletive region.That implies that the ex- isting of carbides at grain boundaries might be the main reason which promotes the HES of steel during aging.展开更多
文摘A new C21-steroidal glycoside with two known compounds were isolated from the root of Cynanchum Stauntonii. Based on the spectral analysis, including MS, 1H NMR, 13C NMR, DEPT, 1H-1H COSY, 13C-1H COSY, HMQC and HMBC, their chemical structures were determinated as glaucogenin-C 3-O-α-L-cymaropyranosyl-（1→ 4）-β-o-digitoxopyranosyl-（1→4）-β-D-canaropyranoside （1）, stigmasterol （2） and ursolic acid （3）.
文摘Insignin A, a new C21-steroidal aglycone having the rare 15,16-seco pregnane skeleton was isolated from the acidic hydrolysis part of the 95% EtOH extract of Biondia insignis. It's structure was identified to be 15R,16-epoxy-3?,14?,16?-trihydroxy-15,16-secopregn-5-ene-20-one based on the spectral data.
文摘A new C_(21) furanoterpene. ent-untenospongin A (2), together with a known related compound. tetradehydrofurospongin-1 (1), has been isolated from the indian marine sponge Hippospongia sp. and its structure was determined on the basis of spectroscopic data.
基金This work was supported by grants from International Foundation for Science in Sweden and National Science Foundation of China.
文摘Besides a series of normal C_(21) steroids from Marsdenia incisa incisa P.T.Li et Y.P.Li, it small amount of novel C_(21) steroidal glycoside (Ⅱ) had been isolated. The mild acidic hydrolysis of (Ⅱ) afforded genin-(Ⅰ). By spectroscopic analyses of IR, ELMS, FDMS, ~1H NMR, ^(13)C NMR (DEPT, PRFT), ~1H-~1H COSY, ~1H-^(13)C COSY for (Ⅰ) and (Ⅱ), (Ⅰ) had been deduced as B-nor (7) -6β-formyl-pregnane-3β, 5β, 8β, 12β, 14β, 17β, 20-heptatol, named neomarinogenin; (Ⅱ) had been deduced as neomarinogenin 3-O-β-D-thevetopyranosyl-(1→-4)-β-Dcymaropyranosyl-(1→4)-β-D-cymaropyranoside, named neomarinoside. Their physical and spectral data were as follows. Neomarinogenin (Ⅰ). A colorless prism from Me_2 CO, mp 202—205℃, 〔α〕_D^(17)+28.81°(MeOH, c0.05), C_(21)H_(34)O_8 (Found: C, 60.76; H, 8.19, C_(21)H_(34)O_8, requires C, 60.87. H, 8.21％); IRv_(max)^(KBr)cm^(-1): 3450 (OH), 1700 (C=O), 1050(C-O-C); EIMS m/z: 397 (M-OH), 380 (397-OH), 379, 378 (M-2H_2O), 36; (M-3H_2O), 342 (M-4H_2O), 333,
文摘Effects of 650℃ aging for 1—1000 h on structure and hydrogen embrittlement susceptibility (HES)of steel Cr21Ni6Mn9N have been investigated.The results show that M_(23)C_6 type carbide precipitates at grain boundaries and Cr-depletive region appears beside them during aging.The precipitates grow and connect each other as the aging time prolongs.Meanwhile, the degree of Cr-depletion aggravates first and then recovers gradually while the aging time is very long,i.e.,1000 h.The HES of the steel increases with increasing aging time but does not reduce with the recovery of Cr content at the Cr-depletive region.That implies that the ex- isting of carbides at grain boundaries might be the main reason which promotes the HES of steel during aging.
