ABSTRACT
Saponin is a kind of complex compounds with triterpenoid or spiral aglycones.Natural saponins are used as substrates,and many novel compounds are obtained by biotransformation technology. Especially, converted products of saponins with strong activities provide valuable lead compounds for the research and development of new drugs. Saponins can be divided into triterpenoid saponin and steroidal saponin according to the structure of the mother nucleus. There are about 89 reported saponin components,including 56 triterpenoid saponins and 33 steroidal saponins. Biological enzyme catalysis,microbial transformation and intestinal microflora transformation are the main bioconversion technologies and key development directions of saponins. The research and optimization technology of biological enzyme and microbial transformation of saponins are the effective methods to prepare active secondary saponins. The biotransformation reaction of saponins mainly includes hydrolysis,redox and rearrangement,resulting in the formation of aglycones,secondary glycosides and their derivatives. The hydrolysis of saponin sugar chains was the main biological transformation pathway, and could generate a number of secondary saponins with less glycosyl groups. The secondary saponins could be absorbed into blood and become real active ingredients in body. Preparation of rare secondary saponins,discovery of lead compounds and development of new drugs are the main directions of biotransformation of saponins. The studies on the metabolism and mechanism of natural saponins by microbial and intestinal microbial biotransformation will also become hotspots. According to relevant papers at home and abroad,the researches on transformation technique,transformation approach and transformation reaction of saponins from natural products in the past thirty years were summarized, and the prospects of research and development were also analyzed to provide scientific basis for further study and comprehensive utilization of these conversion products.
ABSTRACT
<p><b>OBJECTIVE</b>To analyze lymph node (LN) metastasis patterns and determine the appropriate extent of LN dissection in distal-third gastric cancer.</p><p><b>METHODS</b>Clinical data of 545 patients with distal third gastric cancer undergoing radical operation in the Fujian Provincial Hospital between 2001 and 2010 were analyzed retrospectively. The metastasis rate for each LN station was analyzed stratified by the depth of tumor invasion.</p><p><b>RESULTS</b>The incidence of LN metastasis in this cohort was 38.2% (208/545). LN metastasis rate in mucosal cancer was 2.0% (2/99) and involved LNs were limited to station 1 LN stations. LN metastasis rate in submucosal cancer was 18.9% (18/95), significantly higher than that in mucosal cancer (P<0.01). The metastasis rates to groups No.7, 8 and 9 in station 2 were 5.3% (5/94), 3.2% (3/94), and 1.1% (1/89) respectively. In addition, 3 cases (3.2%) had metastasis in station 2 outside the range of groups 7, 8 and 9 including groups No.1, 11p and 12. Gastric cancer invading the muscularis propria or deeper layers showed an significant increased rate of metastasis (P<0.01).</p><p><b>CONCLUSION</b>D1 dissection seems to be sufficient for mucosal cancer. Standard D2 dissection should be performed for cancers of the muscularis propria or deeper. For submucosal cancer, an extended D1+ dissection is required for complete removal of metastatic nodes.</p>