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At least 19 recordsLinked to original sources
PubMed2005

Preventive effect of Abelmoschus manihot (L.) Medik. on bone loss in the ovariectomised rats.

Because the biggest culprit in pathogenesis of osteoporosis is oestrogen deficiency, hormone replacement therapy remained the mainstay for prevention. However most of postmenopausal women are more inclined to use natural alternative. We thus investigated the ability of Abelmoschus manihot, a herbal medicine to prevent bone loss in ovariectomised rats. Female Wistar rats were sham operated (SH: 8) or ovariectomised (OVX: 24). On day 0, OVX rats were randomly assigned to groups as follows: eight received 10% Abelmoschus manihot leaves in their diet, eight were given 15% Abelmoschus manihot leaves and eight were untreated (OVX). Compounds were mixed with a soy protein-free diet and given orally for 3 months. At necropsy, bone mineral density (BMD) in the femur and in its metaphyseal zone was lower in OVX than SH (p<0.05). This osteopenia was prevented by consumption of the highest dose of Abelmoschus manihot leaves. Bone mineral content (BMC) in the total femur and its metaphyseal and diaphyseal subregions was improved, as well (p<0.05). This could be explained by a trend towards decreased bone resorption. The lowest dose did not elicit any significant effect. In conclusion, Abelmoschus manihot consumption, at the dose of 15% in the diet, provided bone-sparing effects by improving both BMD and BMC.

Abelmoschus↗
PubMed2006

Bioreduction of aldehydes and ketones using Manihot species.

Biocatalysis constitutes an important tool in organic synthesis, especially for the preparation of chiral molecules of biological interest. A series of aliphatic and aromatic aldehydes and two ketones were reduced using plant cell preparations from Manihot esculenta and Manihot dulcis roots. The reduced products were typically obtained in excellent yields (80-96%), and with excellent enantiomeric excess (94-98%), except for vanillin. Esters, a nitrile, and an amide were also examined, but were not reduced. Preliminary conversion rate studies are reported. This is the first attempt to perform the biotransformation of carbonyl compounds using Manihot species.

Aldehydes↗
PubMed2002

Cytogenetics of Manihot esculenta Crantz (cassava) and eight related species.

Thirty-nine cultivars of cassava and eight related wild species of Manihot were analyzed in this work for number, morphology and size of chromosomes, prophase condensation pattern and the structure of the interphase nucleus. In four accessions, the chromosome size was measured and in some others, the number of secondary constrictions, meiotic behavior, C-band pattern, CMA/DAPI bands, nucleoli number and the location of 5S and 18S-5.8S-28S rDNA sites were also observed. All investigated accessions showed a similar karyotype with 2n = 36, small metacentric to submetacentric chromosomes. Two pairs of terminal secondary constrictions were observed in the chromosome complement of each accession except Manihot sp. 1, which presented two proximal secondary constrictions. The prophase chromosome condensation pattern was proximal and the interphase nuclei structure was areticulate to semi-reticulate. The meiosis, investigated in seven cultivars and four wild species, was regular, displaying 18 bivalents. C-banding revealed heterochromatin in 9 or 10 chromosomes. The analysis with fluorochromes frequently showed four chromosome pairs with a single CMA+ terminal or subterminal band and a few other chromosomes with DAPI+ unstable bands. Six 45S rDNA sites were revealed by FISH, which seemed to colocalize with six CMA+ bands. Only one chromosome pair presented a 5S rDNA site. The maximum nucleoli number observed per nucleus was also six. These data suggest that all Manihot species present a very similar chromosome complement.

Chromosome Banding↗
PubMed2002

Cassava, Manihot esculenta Crantz, genetic resources: origin of the crop, its evolution and relationships with wild relatives.

About 98 species of Manihot are known. All of them are native to the New World and are concentrated in four regions in Brazil and Central America. All the Manihot species so far examined have 2n = 36 chromosomes. Interspecific hybrids between cassava and its wild relatives show relatively normal meiosis, and further generations can be obtained. Electrophoresis shows affinity among wild species of different sections, and between some of them and cassava. Both polyploidy and apomixis may have contributed to speciation in this genus. Polyploidy produced genetic variability, while apomixis is responsible for perpetuating new hybrid types adapted to different environments. Cassava may have originated by hybridization between two wild Manihot species, followed by vegetative reproduction of the hybrid.

Biological Evolution↗
PubMed1993

Toward the construction of a molecular map of cassava (Manihot esculenta Crantz): comparison of restriction enzymes and probe sources in detecting RFLPs.

The construction of a detailed genetic map of cassava (Manihot esculenta Crantz), classified as a tetraploid species, depends on the ability of cloned sequences to detect polymorphisms. As a first step in developing this map, 200 cloned nuclear sequences generated with different restriction enzymes were hybridized to total digested DNA from eleven cultivated lines and one wild Manihot species, M. aesculifolia. Polymorphism was detected less frequently with both BamHI and EcoRI genomic probes than with PstI, HindIII and XbaI genomic probes. DNA digested with HpaII, DraI and TaqI displayed less polymorphism, whereas DNA digested with EcoRI and EcoRV displayed more polymorphism like that found in lettuce, rice and tomato (Landry et al., 1987; McCouch et al., 1988; Miller and Tanksley, 1990). Four-cutter restriction enzymes displayed less frequency of polymorphism when compared with six-cutter restriction enzymes. Polymorphism displayed by DraI was extremely low, indicating that regions rich in adenine and thymine may not be hot spots for mutation in cassava. Polymorphism detected between cultivated genotypes and M. aesculifolia was dramatically higher than that found among cultivated genotypes.

DNA Probes↗
PubMed1999

Evidence on the origin of cassava: phylogeography of Manihot esculenta.

Cassava (Manihot esculenta subsp. esculenta) is a staple crop with great economic importance worldwide, yet its evolutionary and geographical origins have remained unresolved and controversial. We have investigated this crop's domestication in a phylogeographic study based on the single-copy nuclear gene glyceraldehyde 3-phosphate dehydrogenase (G3pdh). The G3pdh locus provides high levels of noncoding sequence variation in cassava and its wild relatives, with 28 haplotypes identified among 212 individuals (424 alleles) examined. These data represent one of the first uses of a single-copy nuclear gene in a plant phylogeographic study and yield several important insights into cassava's evolutionary origin: (i) cassava was likely domesticated from wild M. esculenta populations along the southern border of the Amazon basin; (ii) the crop does not seem to be derived from several progenitor species, as previously proposed; and (iii) cassava does not share haplotypes with Manihot pruinosa, a closely related, potentially hybridizing species. These findings provide the clearest picture to date on cassava's origin. When considered in a genealogical context, relationships among the G3pdh haplotypes are incongruent with taxonomic boundaries, both within M. esculenta and at the interspecific level; this incongruence is probably a result of lineage sorting among these recently diverged taxa. Although phylogeographic studies in animals have provided many new evolutionary insights, application of phylogeography in plants has been hampered by difficulty in obtaining phylogenetically informative intraspecific variation. This study demonstrates that single-copy nuclear genes can provide a useful source of informative variation in plants.

Biological Evolution↗
PubMed2003

Cassava, Manihot esculenta Crantz genetic resources: VI. Anatomy of a diversity center.

Central Brasil is one of the four centers of diversity of Manihot species. Of 26 wild Manihot species reported to occur in this region, 20 were collected from two limited areas, each less than 100 km in diameter. These two areas are Goiás Velho and Corumbá de Goiás. Considering the Harlan concept of geographic patterns of variation of cultivated crops, it is assumed that the two areas are microcenters of cassava diversity. Topographic, soil and ethnological data of these species were collected and compared.

Brazil↗
PubMed2000

Cross-species amplification of cassava (Manihot esculenta) (Euphorbiaceae) microsatellites: allelic polymorphism and degree of relationship.

Microsatellite amplification was performed on cassava (Manihot esculenta) and six other different species (all wild) of the Manihot genus. We used ten pairs of microsatellite primers previously developed from cassava, detecting 124 alleles in a sample of 121 accessions of the seven species. The number of alleles per locus ranged from four to 21 alleles, and allelic diversity was greater in the wild species than in cassava. Seventy-nine alleles, including unique ones, were detected in the wild species but were not found in the crop. The lower level of heterozygosity in some wild species probably resulted from a combination of fine-scale differentiation within the species and the presence of null alleles. Overall, microsatellite primers worked across the genus, but, with increasing genetic distance, success in amplifying loci tended to decrease. No accession of M. aesculifolia, M. carthaginensis, and M. brachyloba presented a banding pattern at locus Ga-140; neither did one appear for M. aesculifolia at locus Ga-13. Previous work with amplified fragment length polymorphism (AFLP) markers and this microsatellite analysis show that these three wild taxa are the most distant relatives of the crop, whereas the wild forms M. esculenta subsp. flabellifolia and M. esculenta subsp. peruviana appear to be the closest.

Journal Article↗
PubMed2001

Microsatellite variation in cassava (Manihot esculenta, Euphorbiaceae) and its wild relatives: further evidence for a southern Amazonian origin of domestication.

Genetic variation at five microsatellite loci was used to investigate the evolutionary and geographical origins of cassava (Manihot esculenta subsp. esculenta) and the population structure of cassava's wild relatives. Two hundred and twelve individuals were sampled, representing 20 crop accessions, 27 populations of cassava's closest wild relative (M. esculenta subsp. flabellifolia), and six populations of a potentially hybridizing species (M. pruinosa). Seventy-three alleles were observed across all loci and populations. These data indicate the following on cassava's origin: (1) genetic variation in the crop is a subset of that found in the wild M. esculenta subspecies, suggesting that cassava is derived solely from its conspecific wild relative. (2) Phenetic analyses group cassava with wild populations from the southern border of the Amazon basin, indicating this region as the likely site of domestication. (3) Manihot pruinosa, while closely related to M. esculenta (and possibly hybridizing with it where sympatric), is probably not a progenitor of the crop. Genetic differentiation among the wild populations is moderately high (F:(ST) = 0.42, rho(ST) = 0.54). This differentiation has probably arisen primarily through random genetic drift (rather than mutation) following recent population divergence.

Journal Article↗
PubMed2006

[Study of microwave-assisted extraction on total flavones content in Hibiscus manihot L. flower].

OBJECTIVE: To study the extraction process of the total flavones content in Hibiscus manihot L. flower. METHODS: it was investigated that effect of ethanol concentration, extracting time, power of microwave oven and Solid/Liquid ratio (g/mL) on total flavones content using the orthogonal design. RESULTS: The optimum microwave-assisted extraction conditions included: ethanol concentration of 70%, extraction time of 30s, the power of microwave oven of 360w, solid/liquid ratio of 1 : 50 (g/ml) and granularity < or = 80 pore. CONCLUSION: There are broad possibilities for the extraction of the total flavones content from Hibiscus manihot L flower using Microwave-assisted technigue.

Drugs, Chinese Herbal↗
PubMed2006

[Studies on chemical constituents in flower of Abelmoschus manihot].

OBJECTIVE: To study the chemical constituents of Abelmoschus manihot. METHOD: Chromatographic methods were used to isolate compounds from A. manihot, and spectroscopic methods were used to identify the structures. RESULT: Thirteen compounds, myricetin (1), cannabiscitrin (2), myricetin-3-O-beta-D-glucopyranoside (3), glycerolmonopalmitate (4), 2, 4-dihydroxy benzoic acid (5), guanosine (6), adenosine (7), maleic acid (8), heptatriacontanoic acid (9), 1-triacontanol (10) , tetracosane (11), beta-sitosterol (12), beta-sitosterol-3-O-beta-D-glucoside (13) were obtained. CONCLUSION: 2-11 were obtained from the genus for the first time.

Abelmoschus↗
PubMed1995

[Clinical observation on diabetic nephropathy treated with alcohol of Abelmoschus manihot].

Sixty-eight cases of non-insulin dependent diabetes mellitus (NIDDM) complicated with nephropathy were randomly divided into two groups: treated group, 35 cases treated with alcohol extraction of Abelmoschus manihot, Gliclazide and Captopril tablets; control group, 33 cases treated with Gliclazide and Captopril tablets, over a period of 8 weeks. The total effective rate in treated and control group were 83.87% and 31.03%(P < 0.01), urinary micro-albumin were 31.7 mg/L and 76.3 mg/L (P < 0.05), proteinuria were 0.41 g/24h and 0.77 g/24h (P < 0.01), blood beta 2-microglobulin were 3317.8 ng/ml and 3473.1 ng/ml (P < 0.05), urinary beta 2-microglobulin were 367.2 ng/ml and 641.5 ng/ml (P < 0.01), urinary N-acetyl-beta-glucosaminidase (NAG) were 26.3 u/L and 66.7 u/L (P < 0.01), plasma lipid peroxide (LPO) were 6.13 nmol/L and 8.78 nmol/L (P < 0.05), and plasma superoxide anion were 8.36 kcpm and 10.42 kcpm respectively (P < 0.05). It was suggested that Abemoschus manihot alcohol extraction could eliminate oxygen free radicals, alleviate renal tubular-interstitial diseases, improve renal function and reduce proteinuria.

Acetylglucosaminidase↗
PubMed2003

Substrate specificity of mutants of the hydroxynitrile lyase from Manihot esculenta.

Several tryptophan128-substituted mutants of the hydroxynitrile lyase from Manihot esculenta (MeHNL) are constructed and applied in the MeHNL-catalyzed addition of HCN to various aromatic and aliphatic aldehydes as well as to methyl and ethyl ketones to yield the corresponding cyanohydrins. The mutants (especially MeHNL-W128A) are in most cases superior to the wild-type (wt) enzyme when diisopropyl ether is used as the solvent. Substitution of tryptophan128 by an alanine residue enlarges the entrance channel to the active site of MeHNL and thus facilitates access of sterically demanding substrates to the active site, as clearly demonstrated for aromatic aldehydes, especially 3-phenoxybenzaldehyde. These experimental results are in accordance with the X-ray crystal structure of MeHNL-W128A. Aliphatic aldehydes, surprisingly, do not demonstrate this reactivity dependence of mutants on substrate bulkiness. Comparative reactions of 3-phenoxybenzaldehyde with wtMeHNL and MeHNL-W128A in both aqueous citrate buffer and a two-phase system of water/methyl tert-butyl ether again reveal the superiority of the mutant enzyme: 3-phenoxybenzaldehyde was converted quantitatively into a cyanohydrin nearly independently of the amount of enzyme present, with a space-time yield of 57 g L(-1) h(-1).

Alanine↗
PubMed2005

Inversion of stereoselectivity by applying mutants of the hydroxynitrile lyase from Manihot esculenta.

The influence of Trp128-substituted mutants of the hydroxynitrile lyase from Manihot esculenta (MeHNL) on the stereoselectivity of MeHNL-catalyzed HCN additions to aldehydes with stereogenic centers, which yield the corresponding cyanohydrins, is described. In rac-2-phenylpropionaldehyde (rac-1) reactions, wild-type (wtMeHNL) and all MeHNL Trp128 mutants are highly (S)-selective toward the (R) enantiomer of rac-1; this results exclusively in (2S,3R)-cyanohydrin ((2S,3R)-2) with > or =96 % de. The (S) enantiomer of rac-1, however, only reacts (S)-selectively with wtMeHNL to give (2S,3S)-2 with 80 % de, whereas with Trp128 mutants, (R) selectivity increases with decreasing size of the amino acids exchanged. The MeHNL W128A mutant is exclusively (R)-selective, resulting in (2R,3S)-2 with 86 % de. The reaction behavior of rac-phenylbutyraldehyde (rac-5) is comparable with rac-1, which also inverts the stereoselectivity from (S) to (R) when the enzyme is exchanged from wtMeHNL to the W128A mutant. Stereogenic centers not adjacent to the aldehyde group, as in 7 and 9, do not influence the stereoselectivity of MeHNL catalysis, and (S) selectivity is observed in all cases. Stereoselectivity and inversion of stereoselectivity of MeHNL Trp128 mutant-catalyzed cyanohydrin formation can be explained and rationalized with crystal-structure-based molecular modeling.

Aldehyde-Lyases↗
PubMed1994

Purification, characterization, and cloning of alpha-hydroxynitrile lyase from cassava (Manihot esculenta Crantz).

alpha-Hydroxynitrile lyase (HNL, acetone cyanohydrin lyase, EC 4.1.2.37) was purified to homogeneity from young leaves of the cyanogenic tropical crop plant cassava (Manihot esculenta Crantz). The purified protein is a homo-trimer with a subunit relative molecular mass of 28,500 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The active protein is not glycosylated and does not contain a flavin group. HNL exhibits complex kinetics which vary according to substrate concentration and may be related to aggregation of the enzyme. HNL activity against two natural substrates, acetone cyanohydrin and 2-butanone cyanohydrin, and one nonphysiological substrate, 2-pentanone cyanohydrin, was demonstrated. N-terminal and internal peptide sequences, obtained from HNL digested with the endoproteinase Glu-C, were used to design degenerate oligonucleotide primers for polymerase chain reaction with single-strand cDNA, using purified mRNA from cotyledons as template. The resulting DNA fragment was used to probe a cassava cotyledon cDNA library. Four cDNA clones were isolated, sequenced, and shown to contain derived amino acid sequences identical to those obtained from the purified protein.

Aldehyde-Lyases↗
PubMed1994

Investigation of the active site of the cyanogenic beta-D-glucosidase (linamarase) from Manihot esculenta Crantz (cassava). I. Evidence for an essential carboxylate and a reactive histidine residue in a single catalytic center.

The broad-specificity cyanogenic beta-D-glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) (linamarase) from Manihot esculenta Crantz (cassava) was kinetically characterized in mixed substrate systems and with the transition-state analogue glucono(1-5)lactone and a series of 1-thio substrate analogues. The results indicate a common catalytic and a common sugar binding site in the enzyme for all of the investigated substrates. Kinetic parameters of the hydrolysis of linamarin and p-nitrophenyl beta-D-glucopyranoside were determined over the pH range 3.5-9.0. The pH-dependence curves gave apparent pK values of 4.5 (4.6) and 7.1 (7.3) for the free enzyme, while values of 4.5 (3.7) and 9.3 were obtained for the enzyme-substrate complexes, using either linamarin or p-nitrophenyl beta-D-glucopyranoside as the substrate. Kinetic analysis of the modification indicated that one molecule of water-soluble carbodiimide or Woodward's reagent K is required to bind to the enzyme for inactivation. The enzyme was protected against inactivation by the competitive inhibitors p-nitrothiophenyl beta-D-glucopyranoside, beta-D-glucopyranosylamine, and glucono(1-5)lactone. Spectrophotometric analysis at 340 nm showed that from the three carboxylate groups modified by Woodward's reagent K essentially one was protected by p-nitrothiophenyl beta-D-glucopyranoside. During modification Vmax decreased to 30% of that of the unmodified enzyme and Km remained unchanged. The pH dependence of inactivation showed the involvement of a group with a pK value of 4.6, indicating the modification of a carboxyl residue essential for activity. Treatment of the enzyme with the histidine-group-specific reagent diethylpyrocarbonate resulted in 80% loss of enzyme activity, in biphasic kinetics. A treatment with 0.5 M hydroxylamine at pH 7.0 regenerated 92% of the original enzyme activity. The presence of the competitive inhibitor beta-D-glucopyranosylamine protected the enzyme against inactivation, preventing the modification of one histidine residue. Statistical analysis of the residual fractional activity against the number of modified residues indicated that the modification of one histidine is responsible for 40-50% of the inactivation. The pH dependence of the inactivation gave a pK value of 7.0 for the histidine group upon which the activity depends. During modification, Vmax decreased to 30% and Km decreased to 50% of the original values.

Binding Sites↗
PubMed1994

Investigation of the active site of the cyanogenic beta-D-glucosidase (linamarase) from Manihot esculenta Crantz (cassava). II. Identification of Glu-198 as an active site carboxylate group with acid catalytic function.

The broad-specificity cyanogenic beta-D-glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) (linamarase) from Manihot esculenta Crantz (cassava) was irreversibly inactivated by N-bromoacetyl-beta-D-glucopyranosylamine according to pseudo-first-order kinetics with a second-order efficiency constant (ki/Ki = 0.1 min-1 M-1) identical for p-nitrophenyl-beta-D-glucopyranosidase, p-nitrophenyl-beta-D-galactopyranosidase, and linamarase activities of the enzyme. The competitive inhibitor p-nitrothiophenyl-beta-D-glucopyranoside protected the enzyme from inactivation. pH dependence of the pseudo-first-order rate constant of inactivation revealed the involvement of an amino acid side chain in the inactivation process with pKa 7.0, which is very similar to that of the acid catalyst group of the enzyme (pKE2 = 7.2). The involved amino acid, which has to be ionized for the inactivation, was identified as Glu-198 using 14C-labeled inactivator to label the enzyme, cleaving the labeled protein into peptides and then purifying and sequencing the labeled peptide. This residue is highly conserved in the homologous family A beta-glucosidases and family A1-A5 cellulases and lies in a consensus Asn-Glu-Pro motif occurring in all of these enzymes.

Acetylglucosamine↗
PubMed1996

Properties of alpha-hydroxynitrile lyase from the petiole of cassava (Manihot esculenta Crantz).

alpha-Hydroxynitrile lyase (HNL, acetone-cyanohydrin lyase, EC 4.1.2.37) was purified to homogeneity from petioles of cassava (Manihot esculenta Crantz). The purified HNL is a homotetramer with a subunit molecular weight of 25,600 and an isoelectric point of 4.7. The HNL activity exhibits a pH optimum of 5.0 and is stable in the pH range of 6 to 11. The petiole HNL shows a simple Michaelis-Menten kinetics with Km for acetone cyanohydrin of 4.0 +/- 0.9 mM and Vmax of 46.2 +/- 5.0 micromol/min/mg. Several alcohols, aldehydes, and ketones inhibit the HNL activity. The alcohols and ketones are competitive inhibitors, whereas the aldehydes are noncompetitive inhibitors. On the basis of Ki values, inhibitors with 4 carbons are more potent than those with the same functional groups but having fewer or more than 4 carbons.

Alcohols↗