Purification, chemical, and immunochemical properties of a new lectin from Mimosoideae (Parkia discolor)

A glucose/mannose-binding lectin was isolated from seeds of Parkia discolor (Mimosoideae) using affinity chromatography on Sephadex G-100 gel. The protein presented a unique component in SDS-PAGE corresponding to a molecular mass of 58,000 Da, which is very similar to that of a closely related lectin from Parkia platycephala. Among the simple sugars tested, mannose was the best inhibitor, but biantennary glycans, containing the trimannoside core, present in N-glycoproteins, also seem to be powerful inhibitors of the haemagglutinating activity induced by the purified lectin. The protein was characterised by high content of glycine and proline and absence of cysteine. Rabbit antibodies, anti-P. platycephala seed lectin, recognised the P. discolor lectin. However, no cross-reaction was observed when a set of other legume lectins from sub-family Papilionoideae and others from families Moraceae and Euphorbiaceae were assayed with the Parkia lectins. This suggests that Parkia lectins comprise a new group of legume lectins exhibiting distinct characteristics.     

Purification,Chemical, and Immunochemical Properties of a New Lectin from Mimosoideae (Parkia Discolor)

ABSTRACT

A glucose/mannose-binding lectin was isolated from seeds of Parkia discolor (Mimosoideae) using affinity chromatography on Sephadex G-100 gel. The protein presented a unique component in SDS-PAGE corresponding to a molecular mass of 58,000 Da, which is very similar to that of a closely related lectin from Parkia platycephala. Among the simple sugars tested, mannose was the best inhibitor, but biantennary glycans, containing the trimannoside core, present in N-glycoproteins, also seem to be powerful inhibitors of the haemagglutinating activity induced by the purified lectin. The protein was characterised by high content of glycine and proline and absence of cysteine. Rabbit antibodies, anti-P. platycephala seed lectin, recognised the P.discolor lectin. However, no cross-reaction was observed when a set of other legume lectins from sub-family Papilionoideae and others from families Moraceae and Euphorbiaceae were assayed with the Parkia lectins. This suggests that Parkia lectins comprise a new group of legume lectins exhibiting distinct characteristics.     

cDNA cloning and 1.75 A crystal structure determination of PPL2, an endochitinase and N-acetylglucosamine-binding hemagglutinin from Parkia platycephala seeds

Parkia platycephala lectin 2 was purified from Parkia platycephala (Leguminosae, Mimosoideae) seeds by affinity chromatography and RP-HPLC. Equilibrium sedimentation and MS showed that Parkia platycephala lectin 2 is a nonglycosylated monomeric protein of molecular mass 29 407+/-15 Da, which contains six cysteine residues engaged in the formation of three intramolecular disulfide bonds. Parkia platycephala lectin 2 agglutinated rabbit erythrocytes, and this activity was specifically inhibited by N-acetylglucosamine. In addition, Parkia platycephala lectin 2 hydrolyzed beta(1-4) glycosidic bonds linking 2-acetoamido-2-deoxy-beta-D-glucopyranose units in chitin. The full-length amino acid sequence of Parkia platycephala lectin 2, determined by N-terminal sequencing and cDNA cloning, and its three-dimensional structure, established by X-ray crystallography at 1.75 A resolution, showed that Parkia platycephala lectin 2 is homologous to endochitinases of the glycosyl hydrolase family 18, which share the (betaalpha)8 barrel topology harboring the catalytic residues Asp125, Glu127, and Tyr182.     

Parkia pendula lectin as histochemistry marker for meningothelial tumour

Lectins have been intensively used in histochemical techniques for cell surface characterization. These proteins are involved in several biological processes and their use as histochemical markers have been evaluated since they can indicate differences in cell surfaces. Parkia pendula lectin (PpeL) was evaluated as histochemical marker for meningothelial meningioma biopsies. Tissue slices were incubated with PpeL conjugated to horseradish peroxidase (PpeL-HRP) and Concanavalin A-HRP (ConA-HPR) and the binding visualized with diaminobenzidine and hydrogen peroxide. The lectin-tissue binding was inhibited with D-glucose. PpeL showed to be a useful tool for the characterization of meningothelial tumour and clinico-pathological diagnosis.     

The amino-acid sequence of the glucose/mannose-specific lectin isolated from Parkia platycephala seeds reveals three tandemly arranged jacalin-related domains.

A mannose/glucose-specific lectin was isolated from seeds of Parkia platycephala, the most primitive subfamily of Leguminosae plants. The molecular mass of the purified lectin determined by mass spectrometry was 47 946 +/- 6 Da (by electrospray ionization) and 47 951 +/- 9 Da (by matrix-assisted laser-desoption ionization). The apparent molecular mass of the lectin in solutions of pH in the range 4.5-8.5 determined by analytical ultracentrifugation equilibrium sedimentation was 94 +/- 3 kDa, showing that the protein behaved as a non-pH-dependent dimer. The amino-acid sequence of the Parkia lectin was determined by Edman degradation of overlapping peptides. This is the first report of the primary structure of a Mimosoideae lectin. The protein contained a blocked N-terminus and a single, nonglycosylated polypeptide chain composed of three tandemly arranged homologous domains. Each of these domains shares sequence similarity with jacalin-related lectin monomers from Asteraceae, Convolvulaceae, Moraceae, Musaceae, Gramineae, and Fagaceae plant families. Based on this homology, we predict that each Parkia lectin repeat may display a beta prism fold similar to that observed in the crystal structure of the lectin from Helianthus tuberosus. The P. platycephala lectin also shows sequence similarity with stress- and pathogen-upregulated defence genes of a number of different plants, suggesting a common ancestry for jacalin-related lectins and inducible defence proteins.     

Characteristics and composition of Parkia biglobbossa and Jatropha curcas oils and cakes

Parkia biglobbossa (PKBS) and Jatropha curcas (JTC) seeds were analysed for their proximate composition. The seeds oils were analysed for fatty acid, lipid classes, sterols and physicochemical characteristics. Proximate analysis revealed that the percentage crude protein, crude fat and moisture in PKBS were 32.40%, 26.525% and 10.18% respectively and 24.60%, 47.25% and 5.54% in JTC. Campesterol, stigmasterol, beta-sitosterol, Delta5-avenasterol and Delta7-stigmasterol were identified in the seed oils, but beta-sitosterol was most abundant, constituting 71.9% in JTC and 39.5% in PKBS. JTC oil had 72.7% unsaturated fatty acids with oleic acid predominating, while PKBS had 62% unsaturated fatty acids with linoleic acid being the most abundant. Results of lipid classes showed triglyceride as the dominant lipid species in the seed oils. Physicochemical analysis of the seed oils showed that they could be classified as semi drying oils and that they could be found applicable in alkyd resin and soap manufacture.     

Gastroprotective effect of the ethanolic extract of Parkia platycephala Benth. leaves against acute gastric lesion models in rodents

Parkia platycephala Benth. (Leguminosae--Mimosoideae), popularly known as "visgueira", fava bean tree or "fava-de-bolota", is widely found in the Northern and Northeastern regions of Brazil. Its pods are used as cattle food supplement in the drought period. Compounds with a gastroprotective activity were obtained from the genus Parkia. Therefore, this study aimed at investigating the gastroprotective effect of the ethanolic extract of Parkia platycephala Benth. leaves (Pp-EtOH), as well as evaluating its possible mechanisms of action in experimental ulcer induction models. Lesions were induced by absolute ethanol, ethanol-HCl, ischemia-reperfusion and indomethacin in rodents. Pp-EtOH showed a protective effect in the lesion models (66, 48 and 52%, respectively), but it was not able to protect gastric mucosa against indomethacin-induced lesions. Results show a possible participation of the NO-synthase pathway in the gastroprotection and an antioxidant activity, by the increase of the catalase activity. The participation of prostaglandins and potassium channels sensitive to ATP in the gastroprotective effect of Pp-EtOH seems less likely to occur. More comprehensive studies, therefore, should be carried out to elucidate the antiulcerative effects of this promising natural product against this gastrointestinal disorder.     

Cyclic polysulphides from Parkia speciosa

Five polysulphides have been isolated from Parkia speciosa. The structures of four of these have been established as 1,2,4-trithiolane, 1,2,4,6-tetrathiepane, 1,2,3,5,6-pentathiepane (lenthionine) and 1,2,4,5,7,8-hexathionane. A further product has been tentatively assigned either the 1,2,4,6,7- or 1,2,4,5,7-pentathiocane structure.     

Optimization of germination,callus induction,and cell suspension culture of African locust beans Parkia biglobosa (Jacq.) Benth

The present study was carried out to determine the best pre-sowing treatments that can enhance the germination and seedling growth of Parkia biglobosa (Jacq.) Also, to establish and long-term maintenance of calli and cell suspension cultures . The result of various pre-sowing treatments showed that seeds soaked in concentrated H₂SO₄ treatment appeared the highest germination percentage, higher value of plant height, number of leaves, number of branches and stem girth. The MS medium containing 1mg/l 2, 4-D was the best for callus induction of stem explants. The addition of 50 mg /l citric acid to the MS medium was effective for reducing browning of callus than other treatments. However, the viability percent recorded the maximum (87.76%) on the 9^th day while the concentration of viable cells per ml reached the higher record (137.5 viable cell/ml) at the 12^th and cell viability remains (≈ 68.39%) throughout 18 days of culture     

The taxonomy, reproductive biology and economic potential of Parkia (Leguminosae: Mimosoideae) in Africa and Madagascar

The taxonomy, reproductive biology and economic potential of Parkia (Leguminosae: Mimosoideae) in Africa and Madagascar. Three species of the pantropical woody genus Parkia are recognized from continental Africa (including São Tomé), P. biglobosa, P. bicolor and P.filicoidea. A fourth species, P. madagascariensis , is confined to Madagascar. All have capitula of similar structure although details of shape vary. Relatives sharing this capitulum structure occur in the Far East and the Neotropics. Patterns of infraspecific variation are described for the mainland species. Parkia biglobosa shows clinal variation in several leaf characters and P. clappertoniana must be regarded as synonymous. Parkia bicolor shows geographical variation especially in capitulum shape and pod width, and P. filicoidea varies geographically in its pod morphology. The red, balllike capitula are pollinated by bats; other visitors include birds, insects and non-flying mammals. In P. biglobosa a proportion of the capitula is functionally male. The pods of the African species contain mealy pulp. Dispersal involves mammals, especially primates, and birds. Information on uses, chemical composition of the seeds and insect pests is summarized.     

Unusual diversities of seed beetles (Goleoptera: Bruchidae) on Parkia (Leguminosae: Mimosoideae) in Brazil

Earlier studies of the interrelationships between bruchid beetles and their host plants have suggested that the typical pattern tends to be that one bruchid species attacks only a few host species, and that most host species are attacked by only one bruchid species, or at most very few. However, the bruchids attacking Parkia in Amazonian Brazil do not conform to this pattern. The bruchid diversity on Parkia was found to be higher than on any other legume genus yet studied. It is not yet possible to assess whether Parkia is particularly unusual in this regard, or whether such high levels of diversity are typical in Amazonian forests. The number of bruchid taxa attacking any one Parkia species is related to the number of co-occurring closely-related Parkia species. In either taxonomically or geographically isolated host species the bruchid diversity is much reduced.     

Provenance variation in morphology and leaflet anatomy of Parkia biglobosa and its relation to drought tolerance

 Measurements of morphological and anatomical characteristics made on 4-month-old seedlings from five provenances of Parkia biglobosa (Jacq.) Benth., grown in a tropical greenhouse under controlled conditions, showed significant differences between the northern provenances, which represented the Sudan savanna zone, and the southern provenances which represented the forest zone of the species distribution. Seedlings of provenances from the savanna zone showed more xerophytic characteristics than those from the forest zone. They were smaller in height, with a greater number of smaller leaflets per pinnae, a lower specific leaflet mass, smaller palisade and guard cells and a lower ratio of palisade:non-palisade tissue. There were also significant differences in the same characteristics, except palisade cell length, between provenances from the easterly and westerly extremes of the species range. Stomatal conductance measured after 2 weeks of droughting also showed that provenances from the savanna zone had higher values, indicating greater physiological activity and reduced stress, compared with provenances from the forest zone. Multivariate discriminant analysis of the morphological and anatomical characteristics showed that 98% of the seedlings were classified correctly with respect to provenance. The squared distances between provenances were closely related to the geographical distances between locations. Yet, not all variation in leaf anatomy could be explained by the difference in climatic conditions from north to south. Also drought tolerance was not always related to morphological and anatomical features. It is possible that clinal variation within the species from east to west may be interacting with climatic differences from north to south. Received: 2 June 1998 / Accepted: 29 June 1998     

In vitro activity evaluation of Parkia pendula seed lectin against human cytomegalovirus and herpes virus 6.

Human cytomegalovirus (HCMV) in vitro infectivity was inhibited by Parkia pendula seed lectin (PpeL) in contrast to human herpes virus 6 (HHV-6) which was not affected. The antiviral activity was detected for HCMV in human embryo lung (HEL) cells using a microtechnique in culture plates. The assay showed a reduction of cellular infectivity from approximately 95%, at a concentration of 150microg/mL with minimal cytotoxicity (25%). Also, a reduction of 75% was observed in HEL cells at a concentration of 75microg/mL without toxic effect. The reduction on infectivity was observed even after virus pre-adsorption to cells suggesting that this action should occur after virus penetration, in the intracellular replication phase. MT4 lymphocytes and cord blood mononuclear cells (CBMC) were used to evaluate the lectin effect on HHV-6 following the same technique. Lectin concentrations with few or no toxic effects on lymphocytes did not show inhibitory action of HHV-6 cytopathic effect. The results obtained with PpeL demonstrate that it may have an impact in the design of pharmacological strategies to infection of cytomegalovirus.     

Pollination biology and floral scent chemistry of the Neotropical chiropterophilous Parkia pendula

During the past several decades, the pollination biology of Old World plant species pollinated by flying foxes and of New World plants pollinated by highly specialized nectar-feeding glossophagine bats has been studied in detail. However, little is known about Neotropical plants that are pollinated by less specialized phyllostomid bats. Therefore, we studied the pollination biology of Parkia pendula , a tree pollinated by Phyllostomus . Flowers of P. pendula are arranged in capitula, and a capitulum is composed of approximately 800 hermaphrodite flowers and 260 sterile flowers. The sterile flowers produced a total of 7.4 ml nectar per night, with a sugar concentration of 14.95%, and proline as the dominant amino acid. Nectar production is highest at dusk and ends at 03:00 h. The floral scent is dominated by monoterpenoids (97.9%), with ( E )-β-ocimene being the dominant (84.0%) compound. No sulfur compounds were detected. The capitula are heavily visited by four species of phyllostomid bats, of which Phyllostomus discolor is the most abundant (98.9%). Nectar production per capitulum is within the reported range of nectar produced by this pantropical genus (5.0–8.0 ml). This genus-wide range seems to be optimal for attracting non-specialized nectar-feeding bats and forces them to visit capitula of several trees to satisfy their dietary needs, thus increasing the probability of cross-pollination for this plant.     

Gum polysaccharides from three Parkia species

Nigerian gum exudates from Parkia bicolor and P. biglobosa, and gum from the seed pods of P. pendula growing in Costa Rica have been analysed. The two gum exudates are proteinaceous and have closely similar physicochemical properties and compositions, with galactose, arabinose, glucuronic acid and 4-O-methylglucuronic acid as their constituent sugars; rhamnose is absent, and they are dextrorotatory. The gum from the seed pods of P. pendula contains the same constituent sugars in different proportions, and is laevorotatory. These data may be of interest in the continuing studies of plant-animal interactions and mechanisms of seed dispersal associated with the genus Parkia.     

Ethnic differences in use values and use patterns of Parkia biglobosa in Northern Benin

Background

African locust bean tree (Parkia biglobosa) is a multipurpose species used widely in arid Africa by local communities. The present study focused on ethnic differences in use values and use patterns of P. biglobosa in Northern Benin, where the species widely grows. The use values according to the various ethnic groups in the study area have been evaluated in detail for P. biglobosa.

Methods

From 13 ethnic groups, 1587 people were interviewed in the study area using semi-structured questionnaires. Principal Component Analysis was applied to analyze the use value and the use patterns of P. biglobosa for the different ethnic groups.

Results

All interviewees in the study area knew at least one use of P. biglobosa. The various uses identified were medicinal (47%), handicraft and domestic (3%), medico-magic (1%), veterinary (1%), cultural (1%), food (25%) and commercial (22%). The various parts involved in these types of uses were: fruits [shell (2%), pulp (22%) and seeds (36%)], bark (17%), leaves (9%), roots (3%), flowers (1%) and branches (10%). The ethnic group consensus values for P. biglobosa parts showed that the seeds are used the most. The interviewees diversity value (ID) and equitability value (IE) indicated that knowledge concerning P. biglobosa use was distributed homogeneously among the ethnic groups.

Conclusions

P. biglobosa is well-known and used in different ways by the local populations in the study area. Local knowledge on the species is diversified and influenced by ethnic group. Ethnic differences in use values and use patterns of the species were evident in this study.     

湿式消解-石墨炉原子吸收光谱法测定金线莲铅、铜、镉含量

采用湿式消解法对金线莲药材进行处理,石墨炉原子吸收光谱法测定其铅(Pb)、铜(Cu)、镉(Cd)等重金属元素含量。结果表明,Pb、Cu、Cd 三种元素的原子化温度分别是2100、2200和1800 ℃,灰化温度分别是400、800和250 ℃。Pb、Cu、Cd三种元素的检出限分别为0.47、0.50、0.62 μg·L-1,其加标回收率在92.7%～94.0%之间,平均相对标准偏差为1.71%,说明仪器精密度良好,湿式消解-石墨炉原子吸收光谱法能有效测定金线莲药材中Pb、Cu、Cd含量。     

Three new species of Parkia (Leguminosae: Mimosoideae) from tropical South America

Parkia cachimboensis andP. bahiae are described from central and eastern Brazil respectively. The third new species,P. panurensis, which is widespread in central and western Amazonia, has passed hitherto under the incorrect nameP. pectinata (Willd.) Benth.     

Primate seed dispersal leaves spatial genetic imprint throughout subsequent life stages of the Neotropical tree Parkia panurensis

Key message

The Neotropical tree Parkia panurensis shows a spatial genetic structure from the seed to the adult stage that is most likely the outcome of the seed dispersal provided by primates.

Abstract

Seed dispersal and pollination determine the gene flow within plant populations. In addition, seed dispersal creates the template for subsequent stages of plant recruitment. Therefore, the question arises whether and how seed dispersal affects the spatial genetic structure (SGS) of plant populations. In this study, we used microsatellites to analyse the SGS of the Neotropical tree Parkia panurensis (Fabaceae). This plant species is a major food resource for primates and its seeds are mainly dispersed by primates. Seeds were collected during behavioural observations of a tamarin mixed-species troop in north-eastern Peru. Additionally, leaf samples of juveniles and of adults trees of this species were collected throughout the home range of the tamarin troop. A significant SGS for embryos (located within the dispersed seeds) and for non-reproductive plants are found up to a distance of 300 m. This matches the distance within which most seeds are dispersed. In the adult stage, the scale of a significant SGS is reduced to 100 m. While we cannot explain this scale reduction, our study provides the first evidence that primate seed dispersal does influence the SGS of a tropical tree species.