Structure and Physiological Activity of DDMP Saponins in Leguminous Plant

对天然大豆种子中B族皂苷的组成和结构进行了研究。分离得到5种皂苷，按洗脱顺序分别命名为大豆皂苷α，大豆皂苷β，大豆皂苷β，大豆皂苷γ，大豆皂苷γ，大豆皂苷V，大豆皂苷I，大豆皂苷II，大豆皂苷III，大豆皂苷IV，大豆皂苷V、大豆皂苷I、大豆皂苷II、大豆皂苷III和大豆皂苷IV，它们分别以缩醛键连接在大豆皂苷V、I、II、III和IV的C-22上，分别为2，3-dihydro-2，5-dihydroxy-6-methyl-4H-pyran-4-one(DDMP)。这些DDMP结合皂苷被认为是天然大豆种子中真正的皂苷，大豆皂苷I、II、III、IV和V是在提取或浓缩过程中加热产生的人工制品。DDMP皂苷广泛存在于豆科植物中，如从美国花生砧木中分离得到的大豆皂苷。从菜豆和扁豆中分离得到新的DDMP皂苷，分别命名为大豆皂苷αa和扁豆皂苷I。在连接茎和胚芽的纤维维管束中，细胞周围观察到高浓度的DDMP皂素。在活性氧和乙醛存在下，测定了儿茶素的化学发光(CL)。(-)-表没食子儿茶素(EGC)在黄酮类、花青素和儿茶素中具有最强的化学发光。化学发光强度P依赖于活性氧物种X(如H_2O_2)、催化物种Y(如EGC)和受体物种Z(如MECHO)的浓度：p=k[X][Y][Z](k，光子常数)。用黄素酶-NH_2O_4法、ESR和化学发光法测定了DDMP皂苷清除氧自由基的活性。1毫克DDMP皂素/mg显示出相当于ESR自旋捕捉法测得的17.1个单位/毫升的超氧化物歧化酶清除超氧化物歧化酶的活性。我们发现A组皂苷和DDMP皂苷分别是Y相当于EGC，Z相当于MECHO。

The composition and the structures of group B saponins in native soybean seeds were investigated. Five kinds of saponins named soyasaponins alphag, betag, betaa, gammag and gammaa according to elution order from HPLC were isolated, and the structures were characterized as having a 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) group attached by acetal linkage to C-22 of the aglycones soyasaponines V,I,II,III and IV,respectively. These DDMP cojugated saponins are considered to be the genuine saponins in native soybean seeds, and soyasaponins I,II,III,IV and V are artifacts produced by heating during the extraction or concentration process. The DDMP saponins are widely distributed in the leguminous plant such as soyasaponin betag isolated from rootstock of the American groundnut. And new DDMP saponins were isolated from Phaseolus coccineus and Dolichos lablab, named as soyasaponin alphaa and lablab saponine I respectively. A high concentration of DDMP saponin was observed around the cell in fibrovascular bundles connecting the stem to the plumule.The chemiluminescence (CL) of catechins were measured in the presence of active oxygen species and acetaldehyde (MeCHO). (-)-Epigallocatechin (EGC) exhibited the strongest CL among flavonoids, anthocyanins and catechins. The CL intensity, P,was dependent on the concentrations of active oxygen species, X,such as H_2O_2, catalytic species, Y,such as EGC and receptive species, Z,such as MeCHO as follows ; p=k[X][Y][Z] (k, photon constant). DDMP saponins showed oxygen-radical-scavenging activity assayd by using the xanthin oxidase-NH2OH methods, ESR and chemiluminescence. One milligram of DDMP saponin/mg exhibited superoxide-scavenging activity of a degree equvalent to 17.1 units of superoxide dismutase/ml measured by the ESR spin trapping method. We have found that group A and DDMP saponins are Y equivalent to EGC and Z equivalent to MeCHO,respectively.