Alkaloids ofThalictrum collinum
The method of methanolic extraction was applied to the roots. After the methanol has been distilled off, the concentrated extract was treated with 10% sulfuric acid, the acid extracts were alkalinized to pH 9, and the alkaloids were extracted with ether and chloroform. The combined ether-soluble and chloroform-soluble alkaloids obtained were separated into phenolic and nonphenolic bases. The combined nonphenolic tertiary bases were chromat.graphed on a column of alumina (1:70, neutral, activity grade II). The alkaloids were eluted with benzene, benzene--chloroform, chloroform, ethyl acetate, and ethyl acetate-methanol.
New Flavonoid Glycoside from Thalictrum minus
The new flavonoid diglycoside thamiflaside was isolated from the aerial part of Thalictrum minus. The chemical structure of this glycoside was determined as apigenin 7-O-α-L-2″′-methoxyrhamnopyranosyl-(1→6)-β-D-glucopyranoside based on PMR and 13C NMR (DEPT, HSQC, HMBC) physicochemical methods.
Two new organic reference materials for delta13C and delta15N measurements and a new value for the delta13C of NBS 22 oil.
Analytical grade L-glutamic acid is chemically stable and has a C/N mole ratio of 5, which is close to that of many of natural biological materials, such as blood and animal tissue. Two L-glutamic acid reference materials with substantially different 13C and 15N abundances have been prepared for use as organic reference materials for C and N isotopic measurements. USGS40 is analytical grade L-glutamic acid and has a delta13C value of -26.24 per thousand relative to VPDB and a delta15N value of -4.52 per thousand relative to N2 in air. USGS41 was prepared by dissolving analytical grade L-glutamic acid with L-glutamic acid enriched in 13C and 15N. USGS41 has a delta13C value of +37.76 per thousand and a delta15N value of +47.57 per thousand. The delta13C and delta15N values of both materials were measured against the international reference materials NBS 19 calcium carbonate (delta13C=+1.95 per thousand ), L-SVEC lithium carbonate (delta13C=-46.48 per thousand ), IAEA-N-1 ammonium sulfate (delta15N=0.43 per thousand ), and USGS32 potassium nitrate (delta15N=180 per thousand ) by on-line combustion continuous-flow and off-line dual-inlet isotope-ratio mass spectrometry. Both USGS40 and USGS41 are isotopically homogeneous; reproducibility of delta13C is better than 0.13 per thousand, and that of delta15N is better than 0.13 per thousand in 100-microg amounts. These two isotopic reference materials can be used for (i) calibrating local laboratory reference materials, and (ii) quantifying drift with time, mass-dependent fractionations, and isotope-ratio-scale contraction in the isotopic analysis of various biological materials. Isotopic results presented in this paper yield a delta13C value for NBS 22 oil of -29.91 per thousand, in contrast to the commonly accepted value of -29.78 per thousand for which off-line blank corrections probably have not been quantified satisfactorily.