Inhibitory Potency of Erythrina variegata Proteinase Inhibitors toward Serine Proteinases in the Blood Coagulation and Fibrinolytic Systems

The Erythrina variegata Kunitz family trypsin inhibitors, ETIa and ETIb, prolonged the activated partial thromboplastin time (APTT) and also the prothrombin time (PT) of human plasma, but the Kunitz family chymotrypsin inhibitor, ECI, and Bowman–Birk family inhibitor, EBI, from E. variegata hardly prolonged these times. Trypsin inhibitors ETIa and ETIb inhibited the amidolytic activity of factor Xa, and ETIb but not ETIa inhibited plasma kallikrein. Neither ETIa nor ETIb exhibited any inhibitory activity toward β-factor XIIa and thrombin. Furthermore, trypsin inhibitors ETIa and ETIb inhibited plasmin, a serine proteinase in the fibrinolytic system, whereas ECI and EBI did not. These results indicate that Erythrina Kunitz proteinase inhibitors possess different potency toward serine proteinases in the blood coagulation and fibrinolytic systems, in spite of their high similarity in amino acid sequence.     

Binding and precipitating activities ofErythrina lectins with complex type carbohydrates and synthetic cluster glycosides. A comparative study of the lectins fromE. corallodendron,E. cristagalli,E. flabelliformis,andE. indica

Erythrina lectins possess similar structural and carbohydrate binding properties. Recently, tri- and tetra-antennary complex type carbohydrates with non-reducing terminal galactose residues have been shown to be precipitated as tri- and tetravalent ligands, respectively, with certainErythrina lectins [Bhattacharyya L, Haraldsson M, Brewer CF (1988) Biochemistry 271034-41]. The present work describes a comparative study of the binding and precipitating activities of fourErythrina lectins,viz. E. corallodendron, E. cristagalli, E. flabelliformis, andE. indica, with multi-antennary complex type carbohydrates and synthetic cluster glycosides. The results show that though their binding affinities are very similar, theErythrina lectins show large differences in their precipitating activities with the carbohydrates. The results also indicate significant dependence of the precipitating activities of the lectins on the core structure of the carbohydrates. These findings provide a new dimension to the structure-activity relationship of the lectins and their interactions with asparagine-linked carbohydrates.Abbreviations EAL, ECorL, ECL, EFL, and EIL represent the lectins from the seeds ofErythrina arborescens, - E. corallodendron, E. cristagalli, E. flabelliformis, andE. indica respectively - AFOS thetri-antennary complex type oligosaccharide from asialofetuin - AFGP the tri-antennary glycopeptide from asialofetuin - MeGal methyl -d-galactopyranoside Unless stated otherwise all sugars are in thed-configuration.     

Characterization of α-mannosidase from Erythrina indica seeds and influence of endogenous lectin on its activity

α-mannosidase from Erythrina indica seeds is a Zn²⁺ dependent glycoprotein with 8.6% carbohydrate. The enzyme has a temperature optimum of 50 °C and energy of activation calculated from Arrhenius plot was found to be 23 kJ mol^− 1. N-terminal sequence up to five amino acid residues was found to be DTQEN (Asp, Thr, Gln, Glu, and Asn). In chemical modification studies treatment of the enzyme with NBS led to total loss of enzyme activity and modification of a single tryptophan residue led to inactivation. Fluorescence studies over a pH range of 3–8 have shown tryptophan residue to be in highly hydrophobic environment and pH change did not bring about any appreciable change in its environment. Far-UV CD spectrum indicated predominance of α-helical structure in the enzyme. α-Mannosidase from E indica exhibits immunological identity with α-mannosidase from Canavalia ensiformis but not with the same enzyme from Glycine max and Cicer arietinum. Incubation of E. indica seed lectin with α-mannosidase resulted in 35% increase in its activity, while no such activation was observed for acid phosphatase from E. indica. Lectin induced activation of α-mannosidase could be completely abolished in presence of lactose, a sugar specific for lectin.     

Hypaphorine, an indole alkaloid from Erythrina velutina, induced sleep on normal mice

An indole alkaloid (hypaphorine (1)) was isolated from Brazilian medicinal plant, Erythrina velutina (Leguminosae). This compound was investigated for sleep promoting effects in mice, and the results showed that it significantly increased non-rapid eye movement (NREM) sleep time during the first hour after its administration. The NREM sleep time was enhanced by 33% in the experimental mice when compared to that of the controls. This study therefore confirmed its sleep promoting property.     

Three isoflav-3-enes and a 2-arylbenzofuran from the root bark of Erythrina burttii

From the root bark of Erythrina burttii three isoflav-3-enes, 7,4'-dihydroxy-2'-methoxy-6-(1",1"-dimethylallyl)isoflav-3-ene (trivial name, burttinol-A), 4'-hydroxy-2'-methoxy-2",2"-dimethylpyrano[5",6":8,7]isoflav-3-ene (trivial name, burttinol-B), 7,4'-dihydroxy-2'-methoxy-8-(3",3"-dimethylallyl)isoflav-3-ene (trivial name, burttinol-C), and 2-arylbenzofuran, 6,4'-dihydroxy-2'-methoxy-5-(1",1"-dimethylallyl)-2-arylbenzofuran (trivial name, burttinol-D) were isolated. In addition, the known compounds, abyssinone V-4'-methyl ether, bidwillol A, calopocarpin, erybraedin A, erythrabyssin II, isobavachalcone, phaseollidin and phaseollin were identified. The structures were determined on the basis of spectroscopic evidence.     

An arylbenzofuran and four isoflavonoids from the roots of Erythrina poeppigiana

An arylbenzofuran, erypoegin F and four isoflavonoids, erypoegins G-J, together with six known compounds were isolated from the roots of Erythrina poeppigiana, and their structures were elucidated on the basis of spectroscopic evidence. Erypoegin F is a rare 2-arylbenzofuran possessing a formyl group from a natural source, and erypoegin I is the first naturally occurring isoflavonoid with a 2-oxo-3-methylbutyl group.     

Reproductive Biology of Erythrina falcata (Fabaceae: Papilionoideae)1

Reproductive phenology, floral biology, degree of self‐incompatibility, and floral visitors of Erythrina falcata were studied in an Argentinean population. Flowering occurs during the dry season from late August to late October. Flower lifetime is 5–6 d. Phylogenetic studies indicate that E. falcata, together with E. fusca and E. crista‐galli, are included in a basal clade within Erythrina. Its phylogenetic position, floral morphology, and nectar characteristics suggest a hummingbird–passerine mixed pollination system. The flowers are nontubular, and the vexillum (the upper petal of the corolla) covers the other remaining floral parts until displaced by a visiting passerine (Icterus cayanensis) or a hummingbird (Amazilia chionogaster). Both birds act as pollen vectors. Bees were observed as occasional pollinators. Nectar production begins at anther dehiscence and coincides with maximum stigmatic receptivity. The base of the keel forms a secondary nectar reservoir. Controlled pollinations showed that this species is self‐incompatible, although a few fruits develop from selfing. Pollen:ovule ratio (43,200:7) is as expected for a xenogamous plant. Only 1 percent of the flowers set seeds under natural conditions. Possible explanations for the low reproductive success are discussed.     

Phosphorus availability under alley cropping and mulched and unmulched sole cropping systems in Costa Rica

Phosphorus availability was measured in soils under five cropping systems: alley cropping with Erythrina poeppigiana, alley cropping with Gliricidia sepium, sole cropping with Erythrina poeppigiana mulch applied, sole cropping with Gliricidia sepium mulch applied, sole cropping with no mulch. The following parameters were measured: 1) plant-available soil P assessed by P uptake of maize and bean bioassay plants; 2) phosphate desorbable by anion exchange resin; 3) adsorption of added P into isotopically exchangeable and non-exchangeable pools.In the bioassay, P uptake of beans declined in the order: mulched sole-cropped>unmulched sole-cropped>alley-cropped soils. For maize the relative uptake was: mulched sole-cropped>unmulched sole-cropped = alley-cropped soils. These results suggest trees had not incorporated a significant quantity of P into the system after seven years and, probably, there was a decrease in available soil P due to the sequestration of P in the tree biomass. Potentially resin-desorbable P was higher in alley-cropped and mulched sole-cropped soils than in unmulched sole-cropped soils. The adsorption and desorption of added P into and from exchangeable and non-exchangeable pools did not differ between alley-cropped and unmulched sole-cropped soils.Crop yield and crop N, P and K uptake were all higher in the alley crops than in the unmulched sole crop. The supply of P to the crop under alley cropping seems to be dependent on P cycled and released from the mulch. The P cycle in alley cropping appears to be self-sustaining at least under conditions of moderate P fertiliser input.     

刺桐胰蛋白酶抑制剂亲和填料的制备及纯化瑞替普酶

刺桐属胰蛋白酶抑制剂(ETI)是一种丝氨酸蛋白酶抑制剂,能特异性的抑制胰蛋白酶、组织纤溶酶原激活剂(tPA)、瑞替普酶(rPA)等丝氨酸蛋白酶。实验利用ETI工程菌,经诱导表达、体外复性及纯化获得ETI蛋白,并将该蛋白键合到CNBr活化的琼脂糖凝胶,制备ETI亲和填料,纯化瑞替普酶 。     

Nitrate and nitrate reductase in Erythrina caffra seeds: Enhancement of induction by anoxia and possible role in germination

The nitrate level in seed embryonic axes of Erythrina caffra Thunb. which is capable of anaerobic germination, was about 2.5 times higher than in seed axes of Pisum sativum L. a species incapable of anaerobic germination. Nitrate levels in E. caffra seeds decreased during germination and this was not due to leaching. Both NADH- and NADPH-dependent nitrate reductase (NAR) activities increased during germination. The increase was prevented by cycloheximide. The activity of NADH-NAR (EC 1.6.6.1) was higher than that of NADPH-NAR (EC 1.6.6.3). Both NAR activities were higher in anoxia than in air during germination. The NAR activities in Pisum seeds were very much lower than in Erythrina seeds. Anoxia (N₂ or argon) enhanced the induction of NAR by KNO₃ in germinated E. caffra axes. The NADH- and NADPH-NAR activities were induced to equally high levels by KNO₃ under anoxia. The enhancement was depressed by cycloheximide. It is concluded that nitrate and NAR activity may play a role in the anaerobic germination of E. caffra seeds.Abbreviation NAR nitrate reductase Financial support was obtained from the University of the Orange Free State and the Foundation for Research Development