Genetic diversity and population structure of an African yam bean (Sphenostylis stenocarpa) collection from IITA GenBank.

African yam bean, AYB (Sphenostylis stenocarpa), is an underutilized legume of tropical Africa. AYB can boost food and nutritional security in sub-Saharan Africa through its nutrient-rich seeds and tubers. However, inadequate information on germplasm with desirable agro-morphological traits, including insufficient data at the genomic level, has prevented the full exploitation of its food and breeding potentials. Notably, assessing the genetic diversity and population structure in a species is a prerequisite for improvement and eventual successful exploitation. The present study evaluated the population structure and genetic diversity of 169 accessions from the International Institute of Tropical Agriculture (IITA) collection using 26 phenotypic characters and 1789 single nucleotide polymorphism (SNP) markers. The phenotypic traits and SNP markers revealed their usefulness in uniquely distinguishing each AYB accession. The hierarchical cluster of phenotypes grouped accessions into three sub-populations; SNPs analysis also clustered the accessions into three sub-populations. The genetic differentiation (FST) among the three sub-populations was sufficiently high (0.14-0.39) and significant at P = 0.001. The combined analysis revealed three sub-populations; accessions in sub-population 1 were high yielding, members in sub-population 2 showed high polymorphic loci and heterozygosity. This study provides essential information for the breeding and genetic improvement of AYB.

Sphenostylis stenocarpa Seed Extract Attenuates Dyslipidemia in Testosterone Propionate-induced Benign Prostatic Hyperplasia in Rats.

BACKGROUND AND OBJECTIVE: Benign Prostatic Hyperplasia (BPH) is a prevalent disease among older men caused by abnormal proliferation of the prostatic cells. Findings indicate an association between dyslipidemia and BPH. This study aimed at evaluating the effect of ethanol extract of Sphenostylis stenocarpa seed on the lipid profile of rats with testosterone propionate-induced BPH. MATERIALS AND METHODS: A total of 25 male Wistar rats randomized into five groups of five rats each were used. BPH was induced in the rats by subcutaneous injection of testosterone propionate in olive oil for 28 days. The test rats (after BPH induction) were treated with ethanol extract of the plant seed at doses of 200 and 400 mg kg-1 b.wt. The concentrations of total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triacylglycerol were evaluated on the sera of the rats. RESULTS: The BPH control rats (model group) showed a significant (p<0.05) increase in concentrations of total cholesterol, LDL-C, triacylglycerol, with a significant decrease in HDL-C compared to the normal control. Oral administration of the seed extract to the rats significantly reversed these dyslipidemia indicators when compared to the model group. CONCLUSION: This study has shown that ethanol extract of S. stenocarpa seed ameliorated dyslipidemia in testosterone propionate-induced BPH in rats. This suggests that the plant seed may be useful in the prevention of cardiovascular disease.

Influence of extrusion cooking on physicochemical properties and starch digestion kinetics of Sphenostylis stenocarpa, Cajanus cajan, and Vigna subterranean grains.

Thermal degradation of sugars and amino acids, and depolymerization of macromolecules such as starch, proteins and fibre occasioned by high-temperature short-time extrusion cooking modify the physicochemical and functional properties of raw materials. High-temperature short-time extrusion cooking holds promise for the expanded use of non-conventional ingredients as food/feed due to its practicality, increased productivity and efficiency, and ability to retain thermally degradable nutrients during cooking. However, little is known about the effect of the high-temperature short-time extrusion cooking process on the physicochemical properties and starch digestibility of lesser-known grain legumes such as African yam beans (Sphenostylis stenocarpa), Pigeon pea (Cajanus cajan), and Bambara peanut (Vigna subterranean). In this study, we investigate the effect of high-temperature short-time extrusion cooking and extrusion cooking temperature; low (100°C) vs high (140°C) temperatures in a single screw extruder, on hydration characteristics, viscoamylolytic properties, in vitro starch digestibility and digestion kinetics of these grain legumes. We show that water holding capacity and swelling power increased (p < 0.05) with increasing extrusion temperature for Sphenostylis stenocarpa and Vigna subterranean but not Cajanus cajan extrudates. Significant effects of extrusion cooking (i.e unextruded vs 100°C and unextruded vs 140°C) and extrusion temperatures (i.e. 100°C vs 140°C) were observed in peak, trough, final and setback viscosities of all extrudates. Starch digestibility and digestion characteristics were modified with increase in extrusion temperature, however, no effect of extrusion temperatures (i.e. 100°C vs 140°C) on starch digestion kinetics was observed for Sphenostylis stenocarpa and Vigna subterranean except for hydrolysis index (34.77 vs 40.77%). Nutritional and physiological implications of extruded grain legumes in monogastric animal feeding were also highlighted. The Information presented herein will influence expanded use of extruded grain legumes as feed ingredients for intensive monogastric animal feeding.

Morphological, structural and functional properties of starch granules extracted from the tubers and seeds of Sphenostylis stenocarpa.

Sphenostylis stenocarpa (Hochst. ex A. Rich.) Harms, is a legume widely recognized in Africa for its edible starchy tuber and seeds. In the present morphological, structural and functional properties of starch extracted from the tubers and seeds of a same accession of this plant were characterized and compared. With smaller and more angular granules, tuber starch displayed higher resistance toward amylolysis and gelatinization than seed starch. The amylolysis of seed starch resulted in fragmented granules with typical layered structures of growth rings. During their hydrothermal treatments, both tuber and seed starches showed condensed ghosts even at 95°C. This high resistance toward hydrothermal degradation was considered as the basis of the typical pasting properties of these two materials. Both seed and tuber starch exhibited A-type crystalline pattern. Under non-oxidative combustion tuber starch presented a degradation peak at 310°C while seed starch was degraded around 302°C.

Structural and physicochemical characterization of Sphenostylis stenocarpa (Hochst. ex A. Rich.) Harms tuber starch.

Several characteristics of African Yam Bean tuber starch (AYB) were studied and compared with that of a well-known native potato starch (P). The diameter of AYB granules ranged from 5.7µ to 49µ with a median at 19.5µ. During its pasting, AYB exhibited a low peak of viscosity in accordance with its low granules swelling and disintegration capacity. The gelatinization temperature of AYB was 75.2°C while that of P was 60.4°C. AYB was observed to be more stable during thermo-gravimetrical Analysis. Its degradation peak was observed at 308°C while that of P was 303°C. The X-ray diffraction analysis revealed that AYB belongs to the A-type crystalline group instead of C-type as claimed for several legumes starches. The stability of AYB and its capacity to structure starch-water systems make this resource an interesting ingredient for new food and non-food products.

Formulation and Evaluation of Oral Dissolving Films of Amlodipine Besylate Using Blends of Starches With Hydroxypropyl Methyl Cellulose.

BACKGROUND: Natural polymers serve as cheap, non-toxic, biocompatible excipients in oral drug delivery. These advantages inform their uses in the design of drug dosage forms. OBJECTIVES: The aim of the study was to prepare and evaluate oral dissolving films of amlodipine besylate, an anti-hypertensive drug, using starch/polymer blends. MATERIAL AND METHODS: Bambara nut (BAM) and the African yam bean (AYB) starches were individually blended with hydroxypropyl methyl cellulose (HPMC). The material and rheological properties of the blends were determined. Amlodipine besylate was incorporated by dispersion and films were prepared by solvent evaporation method and evaluated for mechanical and drug release properties. RESULTS: The BAM/HPMC blends had higher viscosity values than the corresponding AYB/HPMC blends. All the blends gave a Hausner ratio above 1.25 and Carr's index above 22. Blends of ratio 1 : 1 and 2 : 1 produced good films and were subsequently evaluated. All films disintegrated within 15 mins but had poor folding endurance. BAM/HPMC (1 : 1) and AYB/ /HPMC (2 : 1) released all of the drug content within 30 min. The ranking for dissolution profile was AYB/HPMC (2 :1 ) > BAM/ /HPMC (1 :1 ) > BAM/HPMC (2 : 1) > AYB/HPMC (1 : 1). The type and ratio of starch in the blend influenced the drug release pattern of the films. CONCLUSIONS: Starch/HPMC blend ratios of 1 : 1 and 2 : 1 were found suitable for the formulation of oral dissolving film of amlodipine besylate with good disintegration time and drug release profile.

Sphenostylisins A-K: bioactive modified isoflavonoid constituents of the root bark of Sphenostylis marginata ssp. erecta.

Sphenostylisins A-C (1-3), three complex dimeric compounds representing two novel carbon skeletons, along with an additional eight new compounds, sphenostylisins D-K (4-11), were isolated from the active chloroform-soluble extract of the root bark of Sphenostylis marginata ssp. erecta using a bioactivity-guided isolation approach. The structures were elucidated by means of detailed spectroscopic analysis, including NMR and HRESIMS analysis, and tandem MS fragmentation was utilized to further support the structures of 1-3. The absolute configuration of sphenostylisin C (3) was established by electronic circular dichroism analysis. Plausible biogenetic relationships between the modified isoflavonoids 1-11 are proposed, and a cyclization reaction of 9 was conducted to support one of the biogenetic proposals made. All of these pure isolates were evaluated against a panel of in vitro bioassays, and among the results obtained, sphenostylisin A (1) was found to be a very potent NF-κB inhibitor (IC50 = 6 nM).

Evaluation of the effect of processing methods on the nutritional and anti-nutritional compositions of two under-utilized Nigerian grain legumes.

The nutritional and anti-nutritional compositions of African Yam Bean (AYB) and Lima bean flours under different processing methods were determined. Nutritional and anti-nutritional properties studied include moisture content, crude protein, crude fibre, ash content, ether extract, carbohydrate, tannin, protease inhibitor and phytate. The moisture content of AYB flours ranged from 9.31 to 9.61% while that of lima beans ranged from 9.32 to 9.56%. There is a significant different among the samples when the unprocessed AYB (control) and the processed AYB were compared. The same trend was also observed with lima bean flours. However, some nutrient did not show significant variations with processing. It was observed that samples of soaked/de-hulled AYB have the least protease inhibitor of 0.73 mg/100 g and it is significantly different from the unprocessed samples. Soaked/de-hulled flours of both AYB and lima beans have the most percentage decrease in anti-nutritional content. Lima bean flours were observed to have higher anti-nutritional content than AYB. The percentage decrease of anti-nutritional factors in the samples is proportionally higher than that of the nutrients. The nutritional and anti-nutritional compositions of the samples suggest that processed African Yam Bean (AYB) and Lima bean flours would have useful application in fabricated foods.

The proximate, mineral, and toxicant compositions of four possible food security crops from southeastern Nigeria.

The proximate, nutritional, and antinutritional compositions of the raw, cooked, and roasted samples of four Nigerian indigenous seeds-Sphenostylis stenocarpa, Pentaclethra macrophylla, Mucuna flagellipes, and Citrullus colocynthis-were evaluated. Also estimated were zinc and divalent cation bioavailability of the seeds using millimolar ratios/kg dry weight of [calcium]/[phytate], [phytate]/[zinc], [calcium][phytate]/[Zn], and [phytate]/[total phosphorus]. The results obtained revealed that the seeds of P. macrophylla and C. colocynthis had high protein and lipid levels. All the seeds were also found to have high energy value and low moisture content. Mineral analysis showed the presence of Na, K, Ca, and Mg in appreciable quantities and Zn, I, Fe, and Se in minute quantities. Antinutritional analyses indicated the presence of traces of tannin, oxalate, phytate, saponin, and cyanide in the samples. The various processing techniques had significant (P ≤ .05) effects on the measured parameters. The calculated [Ca][phytate]/[Zn] molar ratios revealed that these seeds had values above the critical level of 0.5 mL/kg, thus indicating reduced bioavailability of zinc. In view of the high nutrient contents, low antinutritional contents after processing, and their superabundance, these seeds could be cheap nutrient sources. The implications of these findings with regards to food security are enormous.

Pretreatment of African yam bean (Sphenostylis stenocarpa): effect of soaking and blanching on the quality of African yam bean seed.

The effect of pretreatment (soaking in sodium salts and blanching) on hydration coefficient (HC), chemical composition, texture, and color of African yam bean (AYB) was investigated. Soaking in water and in salt solutions increased the HC and about 90% of final HC values were attained at 12 and 4 hr of soaking for whole and dehulled beans, respectively. Protein content was slightly increased by soaking and blanching while ash and fat contents were reduced. Generally, a combination of dehulling and wet-processing reduced firmness of the beans more than soaking or blanching of the whole beans. Antioxidant activity was lowest (3260 TE(3)100 g) in cream-colored beans and highest (16,600 TE/100 g) in brown-colored beans. The tannin contents of unprocessed cream-colored beans and dehulled wet-processed marble variety were not significantly different (p > 0.05). The levels of tannins in the marble variety were reduced by blanching for 40 min (19.2%), soaking for 12 hr (16.0%), dehulling (72.0%), dehulling and blanching (88.8%). The whiteness of bean flours was increased significantly by dehulling, slightly by wet-processing of marble variety, and reduced significantly by wet-processing of cream-colored beans.

Effect of heat treatment on the proximate composition, energy values, and levels of some toxicants in African yam bean (Sphenostylis stenocarpa) seed varieties.

The effects of heat treatments on the proximate composition, energy content, and levels of some antinutritional factors in brown and marble-colored African yam bean (AYB) seed flours were investigated. In raw brown and marble-colored AYB seed flours; moisture content, dry matter, crude protein, crude fat, ash, total carbohydrate and caloric value did not differ significantly at the 5% level. Autoclaving and cooking slightly increased the moisture level. Crude protein, crude fat, and ash contents were decreased by autoclaving and were further decreased by cooking. The decrease was not, however, considerable for the AYB that is not eaten raw and whose full nutritional potential as a legume can be derived only when heat treated, as previous reports have indicated for legume seeds. The levels of the toxicants were generally higher in the raw brown AYB compared to the marble-colored, and were generally reduced by both autoclaving and cooking. In the most commonly available and consumed marble-colored AYB, autoclaving at 121 degrees C, 15 psi for 20 min decreased cyanogenic glycosides by 46%, oxalate by 48.9%, tannin by 15.0%, saponin by 14.8% and trypsin inhibitors by 61.3% while cooking for 3.5 hours in tap water decreased these toxic factors by 66.5%, 70.3%, 72.2%, 48.7%, and 86.0%, respectively. The results indicate that for raw samples, varietal difference did not significantly affect nutrient composition though the toxicants were generally higher in the brown AYB than the marble-colored. Autoclaving decreased both nutrient value and the level of toxicants in the two seed types; values were further reduced by cooking. Of the toxicants, trypsin inhibitor was found to be the most heat-labile and of the heat treatment methods, cooking to tenderness is recommendable.