[Two new flavonoid glycosides from Nervilia fordii].

Two new flavonoid glycosides were isolated from the aerial parts of Nervilia fordii by various chromatographies such as D101 macroporous resin, ODS and preparative HPLC chromatographic techniques. Their structures were elucidated as rhamnocitrin-3-O-ß-glucopyranosyl-4'-O-ß-galactosyl-(1→3)-glucopyranoside(1) and 7,3'-di-O-methylquercetin-4'-O-[ß-galactosyl-(1→3)-ß-glucopyranosyl]-3-O-ß-glucopyranoside(2) on the basis of extensive spectroscopic analyses, including 1D-, 2D-NMR, HR-ESI-MS and analytical hydrolysis.

[Concentrations of different carbon and nitrogen fractions in rhizosphere and non-rhizosphere soils of typical plant species in mountainous area of southern Ningxia, Northwest China].

Taking the rhizosphere and non-rhizosphere soils of five typical plants Agropyron cristatum, Artemisia frigida, Pseudoraphis bungeana, Thymus mongolicus, and Artemisia sacrorum in a mountainous area of southern Ningxia as test objects, this paper studied their C and N forms contents. The C and N forms contents in the rhizosphere and non-rhizosphere soils differed with plant species. In the rhizosphere soil of A. sacrorum, the C content was the highest, with the total soil organic C (TOC), light fraction organic C (LFOC), and heavy fraction organic C contents being 22.94, 1.95, and 20. 88 g kg-1, respectively. In the rhizosphere soil of P. bungeana, the N content was the highest, with the total N (TN), mineralizable N (MN), and available N contents being 2.05 g kg-1 , 23.73 mg kg-1, and 11.99 mg kg-1 , respectively. In the rhizosphere soil of A. frigida, the LFOC/TOC and MN/TN ratios were the highest, which benefited the C and N transformed into more active forms. Light fraction organic C and mineralizable N could be used as the sensitive indicators of plant habitat change. For the five plant species, the contents of different C and N forms in the rhizosphere soil were generally higher than those in the non-rhizosphere soil.