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Vitamin C contents measured as ascorbic acid, in thirty-eight samples of tropical leafy vegetables and foods were determined by two methods. One was by cyclic voltammetry using glassy carbon, Ag/AgCl and platinum electrode system in 0.1M phosphate buffer, pH 2.0 containing 1mM Na 2 EDTA in a potential range of 200 mV – 1000 mV using a scan rate of 50 mV/S. The anodic peak current for the electrochemical oxidation of ascorbic acid to dehydroascorbic acid was recorded at 580 mV. The other method involved titration of aqueous mixtures of the samples using N-bromosuccinimide. Samples identified to be rich in vitamin C include red pepper (123.73 mg/100 g) and the leaves of white camwood (211.20 mg/100 g), climbing black pepper (181.19 mg/100 g), curry plant (140.50 mg/100 g), fluted pumpkin (129.39 mg/100 g), amaranth globe (97.49 mg/100 g) and jute mallow (serrated edge, 89.94 mg/100 g). Boiling of aqueous mixtures of some vegetables reduced the vitamin C content by 20-43%. The results obtained by both methods were comparable for several samples but were appreciably different for some green leafy vegetables. The data in this report further enlarge the database of vitamin C contents in tropical fruits and vegetables which are sparse in literature and will serve as a useful guide in the selection of plants which are rich in vitamin C. The relevance of the vitamin C contents with medicinal uses of some of the plants is discussed.
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Int. J. Electrochem. Sci., 5 (2010) 105 - 115
International Journal of
Vitamin C Contents of Tropical Vegetables and Foods
Determined by Voltammetric and Titrimetric Methods and
Their Relevance to the Medicinal Uses of the Plants
M. Ogunlesi
, W. Okiei, L. Azeez, V. Obakachi, M. Osunsanmi, G. Nkenchor
Chemistry Department, University of Lagos, Akoka, Lagos, Nigeria
Received: 29 August 2009 / Accepted: 11 January 2010 / Published: 31 January 2010
Vitamin C contents measured as ascorbic acid, in thirty-eight samples of tropical leafy vegetables and
foods were determined by two methods. One was by cyclic voltammetry using glassy carbon, Ag/AgCl
and platinum electrode system in 0.1M phosphate buffer, pH 2.0 containing 1mM Na
EDTA in a
potential range of 200 mV 1000 mV using a scan rate of 50 mV/S. The anodic peak current for the
electrochemical oxidation of ascorbic acid to dehydroascorbic acid was recorded at 580 mV. The other
method involved titration of aqueous mixtures of the samples using N-bromosuccinimide. Samples
identified to be rich in vitamin C include red pepper (123.73 mg/100 g) and the leaves of white
camwood (211.20 mg/100 g), climbing black pepper (181.19 mg/100 g), curry plant (140.50 mg/100
g), fluted pumpkin (129.39 mg/100 g), amaranth globe (97.49 mg/100 g) and jute mallow (serrated
edge, 89.94 mg/100 g). Boiling of aqueous mixtures of some vegetables reduced the vitamin C content
by 20-43%. The results obtained by both methods were comparable for several samples but were
appreciably different for some green leafy vegetables. The data in this report further enlarge the
database of vitamin C contents in tropical fruits and vegetables which are sparse in literature and will
serve as a useful guide in the selection of plants which are rich in vitamin C. The relevance of the
vitamin C contents with medicinal uses of some of the plants is discussed.
Keywords: Vitamin C, Cyclic voltammetry, N-bromosuccinimide, Tropical leafy vegetables,
Medicinal uses
Most tropical countries have vegetation containing a diversity of leafy vegetables such as
spinach, amaranth, lettuce that serve as indispensible constituents of the human diet. The use of green
leafy vegetables for the preparation of soups cuts across different cultures in Nigeria and other parts of
West Africa. Vegetables supply the body with minerals, vitamins, certain hormone precursors as well
as proteins and energy [1-4]. Consumption of fruits and vegetables in diet has been reported to protect
Int. J. Electrochem. Sci., Vol. 5, 2010
the human body from degenerative diseases [5, 6]. In addition vegetables are important in the diets of
postpartum women as they aid the contraction of the uterus. The main protective action of vegetables
has been attributed to the antioxidants present in them. The oxidative stress experienced by a tissue,
organelle or organ results from the balance between the production and removal of potentially
damaging reactive oxygen species. Antioxidants can prevent the chemical damage caused by reactive
oxygen species such as free radicals that are generated by a variety of sources including pesticides,
tobacco smoke, exhaust fumes, certain pollutants and organic solvents [7-9]. The potential cancer-
inducing oxidative damage might be prevented or limited by dietary antioxidants found in fruits and
Vitamin C also known as ascorbic acid is a water soluble antioxidant which is found in variable
quantities in fruits and vegetables [10, 11] and has been found to prevent tissue damage [12-14]. It has
been identified to prevent sperm agglutination thus making them more motile with resultant
improvement in male fertility. It also enhances sperm quality [15, 16]. Several doctors in Nigeria
routinely prescribe vitamin C to aid recovery in several ailments and diseases including cold, cough,
influenza, sores, wounds, gingivitis, skin diseases, diarrhoea, malaria and bacterial infections.
The increased knowledge of the role of vitamin C has necessitated the development of accurate
and specific methods for its determination. Numerous methods based on instruments, titrations or
colour-formation reactions are available in literature for the determination of vitamin C. Instrument-
based methods which involve the use of specialized and expensive equipment have been reported [17-
Several workers who reported the contents of vitamin C in leafy vegetables grown in Nigeria
and other tropical countries used titrimetric [21-25] and spectrophotometric methods [26, 27]. Direct
spectrophotometric determination of vitamin C in the ultraviolet region is prone to matrix effect since
many organic compounds in complex samples may also exhibit ultraviolet absorbance. Thus there is a
need to adopt a procedure that will determine the contents of vitamin C in tropical leafy vegetables
accurately. Electrochemical methods such as cyclic voltammetry can be used because ascorbic acid is
readily oxidized to dehydroascorbic acid, thus the reaction is electroactive [28-31]. In the cyclic
voltammetric method there is no need to determine end point, thus no error arises from this and there is
little interference by colour. The method is sensitive, fast and peak currents are recorded by the
instrument hence no reading error. In a previous report, we presented values of vitamin C contents in
fifty tropical fruits and seeds determined by cyclic voltammetry and compared to the values obtained
by titrimetric method using N-bromosuccinimide (NBS) [32]. In order to enlarge the database, the
values of vitamin C contents in several tropical leafy vegetables and foods are hereby presented. The
medicinal uses of the plants in diseases where vitamin C can promote healing are discussed.
2.1. Materials and Methods
N-Bromosuccinimide, L-ascorbic acid, sodium dihydrogen phosphate and oxalic acid were
purchased from Sigma-Aldrich Chemie (Steinheim, Germany). The reagents and reference solutions
Int. J. Electrochem. Sci., Vol. 5, 2010
were prepared daily and stored in amber bottles to avoid oxidation. 0.1 M phosphate buffer solution
was made up from 0.1M NaH
and adjusted to pH 2.0 with phosphoric acid. pH measurements
were made with a Metrohm pH meter model 780. De-ionized water was used for the preparation of all
2.2. Samples Selected For Analysis
38 samples of tropical leafy vegetables and foods commonly consumed in Nigeria were
obtained from Nigerian Institute of Horticulture (NIHORT), Ibadan, Nigeria and Mushin and Oyingbo
markets in Lagos and environs. The samples obtained from the open markets were identified in
NIHORT. The vegetable and food samples analyzed include, African bush mango leaves (Oro,
Yoruba) (Irvingia gabonesis), amaranth globe leaves (Utazi, Igbo), (Gongronema latifolium), bitter
leaf (Vernonia amygdalina), cabbage leaves (Brassica oleracea), carrot (Daucus carota), climbing
black pepper (leaves and seeds) (Uziza, Igbo) (Piper guinenses), cucumber unpeeled (Cucumis
sativus), curry leaf (Murraya koenigii), fluted pumpkin leaves (Ugu, Igbo) (Telferia occidentalis),
ginger (unpeeled) (Zingiber officinale), green (Amunututu, Yoruba) (Basella alba), green amaranth
(tete, Yoruba) (Amaranthus hybridus), groundnut seeds (Arachis hypogaea), jute mallow leaves
(serrated edge) (Ewedu awoyaya, Yoruba) (Corchorus spp), jute mallow leaves (smooth edge) (Ewedu
angbadu, Yoruba) (Corchorus olitorius), koko vine leaves (Okazi, Igbo) (Gnetum africanum), lemon
grass leaves (Cymbopogon citratus), lettuce (Lactuca sativa), locust bean (Igba, Yoruba) (Parkia
biglobosa), mint leaf (Efinrin, Yoruba) (Ocimum gratissimum), miracle berry leaves (Ewe moinmoin,
Yoruba) (Thaumatococcus danielii), myriantus leaves (Ujuju, Igbo) (Myrianthus arboreus), nut grass
(Ofio, Yoruba) (Cyperus escillentus), Potato (Irish) (Solanum tuberossum L), potato (sweet) (Ipomoea
batatas), raddish (red) (Raphanus sativus), raddish (white), (Raphanus sativus acanthiformis), roselle
calyx [(Isapa,Yoruba) Hibiscus sabdariffa, green variety)], roselle calyx [(Zobo, Hausa) (Hibiscus
sabdariffa, red variety)], sour sop (Annona muricata), spinach (Spinacia oleracea), water hyacinth
(Eichhornia crassipes) which is used as animal feed, water leaf (Gbure, Yoruba) (Talinum
triangulare), water lettuce (Oju-oro, Yoruba) (Pistia stratioles), white camwood leaves (Oha, Igbo)
(Pterocarpus mildbraedii) and yam (Dioscorea spp). Honey though not a vegetable was included in
the samples because it is added to some plant materials and juices in several dietary menu and herbal
preparations. (Yoruba and Igbo are some Nigerian Languages).
2.3. Determination of ascorbic acid by titration with N-bromosuccinimide
The determination was essentially as described in a previous report [32]. A weighed amount of
the sample (5 g) was washed, minced and blended with 0.5% oxalic acid solution for approximately
one minute and filtered through glass wool. The filtrate was transferred to a 100 cm
volumetric flask
and the volume made up to the mark with 0.5% oxalic acid solution. A mixture of 10 cm
of the
sample solution, 2 cm
of 3 % ethanoic acid, 5 cm
of 4 % KI and 10 drops of starch indicator was
titrated using 0.01% N-bromosuccinimide as titrant. The mean of three titre values was recorded. All
Int. J. Electrochem. Sci., Vol. 5, 2010
analyses were done in triplicate. The ascorbic acid contents in the samples were obtained from the
calibration curves and were used to obtain the values in mg/100 g of sample.
2.4. Determination of ascorbic acid using cyclic voltammetry [32]
A BASI-Epsilon potentiostat/galvanostat was used in the study. A weighed amount (5-6 g) of
the sample was minced and blended with 30 cm
of the phosphate buffer for approximately one
minute. The homogenized sample was filtered through glass wool. 15 cm
of the filtrate was
transferred to the electrochemical cell, purged with nitrogen for 10 min before scanning the potential
between 200 mV and 1000 mV using a three electrode system consisting of glassy carbon (3 mm) as
working electrode, Ag/AgCl as reference and platinum (1.6 mm) as the auxiliary electrode. The values
of the anodic peak current obtained at 580 mV were used to calculate the concentration of the ascorbic
acid in the vegetable samples using the calibration curve.
2.5. Effect of Heat on Vitamin C Contents of Some Vegetables
The vitamin C contents of jute mallow leaves (C. olitorius), bitter leaf (V. amygdalina) and
fluted pumpkin leaves (T. occidentalis) were also determined by cyclic voltammetry after boiling them
in water for 20 min to ascertain the effect of heat on the vitamin C contents of these leafy vegetables.
The voltammograms of the calibration and the generated calibration curve were as reported
previously [32]. The voltammograms for the determination of ascorbic acid content of jute mallow
(Corchorus olitorius) before and after boiling are shown in Figures 1a and 1b.
Figure 1. Voltammograms of Corchorus olitorius extract in 0.1M phosphate buffer, pH 2.0. a=before
boiling; b=after boiling in water for 20 min.
Table 1 shows the ascorbic acid contents of the different vegetables and foods determined by
the two methods. Vegetables found to have high concentrations of ascorbic acid (as measured by
Type a quote
Int. J. Electrochem. Sci., Vol. 5, 2010
cyclic voltammetry) in the range of 90-211 mg/100 g of sample include the leaves of amaranth globe,
climbing black pepper, curry leaves, fluted pumpkin, jute mallow (serrated edge) red pepper and white
camwood. Lower but significant levels of ascorbic acid determined by cyclic voltammetry in the range
of 10-75 mg/100 g of sample were found in African bush mango leaves, bitter leaf, cabbage, climbing
black pepper seeds, ginger (unpeeled), green leaves, green amaranth, groundnuts, jute mallow (smooth
edge), koko vine leaves, lettuce, locust bean, mint leaves, miracle berry leaves, myrianthus leaves, nut
grass, potato (Irish), raddish (red and white), roselle calyx (green and red), sour sop, spinach, water
hyacinth, water leaf, water lettuce and honey. Thus when honey is added to menu or herbal
preparations, there is enhancement of vitamin C content.
Low levels of ascorbic acid in the range of 6-10 mg/100 g (cyclic voltammetric determination)
were found in carrot, cucumber, lemon grass, potato (sweet) and yam.
Comparing the values obtained by the two methods, it is observed that the values differ by not
more than 10 mg/100 g that is, 0.1 mg/g in 28 samples, thus are comparable. In 6 samples, the values
differ by 10-20 mg/100 g of sample. In three of these, the differences are 12.58, 10.62, 11.97 mg/100 g
in carrot, green amaranth leaves and jute mallow leaves (serrated edge) respectively. These values are
just above the 10 mg/100 g and can be considered reasonable. The remaining three samples are locust
bean, water leaf and roselle calyx (red variety) where the differences are 19.47, 14.90 and 13.86
mg/100 g respectively. It is also observed that in all the six samples, except green amaranth, the values
obtained by titrimetric are consistently higher. Thus the differences may be due to inaccurate detection
of the end point especially in the coloured materials. However, in five samples, namely bitter leaf,
climbing black pepper leaves, curry leaves, fluted pumpkin leaves and white camwood leaves, the
differences are 93.32, 122.1, 39.66, 41.90 and 82.23 respectively. The values obtained by cyclic
voltammetry are higher in climbing black pepper leaves, curry leaves and white camwood leaves.
Interferences with the reagent or the working electrode by enzymes in the samples may account for the
differences observed.
The effect of heat on the ascorbic acid content of vegetable samples is shown in Figures 1a and
1b for jute mallow leaves (C. olitorius). The vitamin C content of 40.21 mg/100 g for the fresh sample
was found to decrease to 30.65 mg/100 g after boiling the vegetable in water for 20 min. The
reductions of 21% and 47% in the vitamin C contents of bitter leaf (V. amygdalina) and fluted
pumpkin leaves (T. occidentalis) were similarly obtained when these samples were boiled in water for
20 min.
Ejoh et al., 2005 reported ascorbic acid content of 166.5 mg/100 g for bitter leaf (V.
amygdalina) by titrimetric method using the N-bromosuccinimide [22]. Chinma and Igyor, 2007 [25]
reported 14.61 mg/100 g, 21.03 mg/100 g and 12.50 mg/100 g for climbing black pepper leaves,
amaranth globe leaves and white camwood leaves respectively by titrimetric method using 2,6-
dichloroindophenol reagent after the samples had been washed in water and dried in the oven at 60
for 24 h. The 2,6 dichloroindophenol reagent and the excessive exposure of the samples to heat make it
difficult to draw any comparison between the values of Chinma and Igor [25] and those contained in
this report.
Int. J. Electrochem. Sci., Vol. 5, 2010
Table 1. Vitamin C contents of tropical vegetables and foods obtained by cyclic voltammetry (CV)
and titration with N-bromosuccinimide (NBS).
Sample Amount of ascorbic
uses [33]
Common Name Botanical Name CV
1. African Bush
mango leaves
[Oro (Yor)]
23.30 27.51 18 4.21 Spleen
2. Amaranth globe
leaves [Utazi
97.49 100.00 3 2.51 Sore gums
3. Bitter leaf
[Ewuro (Yor)]
32.15 125.47 290 93.32 Gingivitis,
malaria, anti-
4. Cabbage leaves Brassica
var capitata
23.05 13.59 41 9.46 Skin
Daucus carota
6. Climbing black
pepper leaves.
Uziza (Igbo)
Piper guinenses 181.19 59.01 67 122.18 Impotence,
7. Climbing black
pepper seeds.
Piper guinenses 14.59 15.48 6 0.89 Impotence,
8. Cucumber
Cucumis sativus 6.99 14.35 105 7.36 Diuretic
9. Curry leaves Murraya
140.50 100.84 28 39.66 Herpes, fever
10. Fluted Pumpkin
leaves. Egusi
iroko (Yor), Ugu
129.39 171.29 32 41.90 Anti-
cancer, blood
11. Ginger (unpeeled)
11.50 15.00 30 3.50 Cold, cough,
12. Green leaves.
Basella alba 65.32 70.15 7 4.83 Laxative
13. Green amaranth
Tete abalaye,
60.12 49.50 18 10.62 Eye diseases,
diuretic, anti-
14. Groundnuts Arachis
43.74 42.95 2 0.79 Antimicrobia
15. Jute mallow
Corchorus spp 89.94 101.91 13 11.97 Abscesses,
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edge). Ewedu
awoyaya (Yor)
16. Jute mallow
leaves (smooth
edge) Ewedu
40.21 44.74 11 4.26 Abscesses,
17. Koko vine leaves
Okazi, (Igbo)
56.27 46.36 18 9.91 Wounds,
colds and
18. Lemon grass
9.37 10.00 7 0.63 Malaria,
coughs, cold,
19. Lettuce leaves Lactuca sativa 22.27 13.00 42 9.27 Diuretic,
20. Locust bean.
[Igba (Yor)]
Parkia biglobosa 73.23 92.65 27 19.47 Wounds,
malaria, high
21. Mint leaf.
Efinrin-nla (Yor)
52.75 46.00 13 6.75 Wounds, anti
22. Miracle berry
leaves. [Ewe
28.67 26.40 8 2.27
23. Myriantus leaves
[Ujuju (Igbo)]
15.93 10.55 34 5.38 Dysentery,
24. Nut grass
, (Yor)]
11.45 13.37 17 1.92
25. Potato (Irish) Solanum
11.45 8.00 30 3.45
26. Potato (sweet) Ipomoea batatas 6.15 4.28 30 1.87 Boils,
27. Raddish (red) Raphanus
36.20 36.45 1 0.25
28. Raddish (white) Raphanus
39.19 40.82 4 1.63
29. Red pepper
[Bawa (Hau)]
Capsicum spp 123.73 126.05 2 2.32 Colds. Anti-
30. Roselle calyx
(green variety)
[Isapa (Yor)]
27.50 29. 20 6 1.70 Cough,
dressing of
31. Roselle calyx (red
32.14 46.00 43 13.86 Cough,
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[Zobo (Hau)] dressing of
32. Sour sop Annona muricata
10.51 13.63 30 3.12 Fever
33. Spinach Spinacia
35.67 38.75 9 3.08
34. Water hyacinth Eichhornia
10.19 16.34 60 6.15 Skin care,
35. Water leaf [Gbure
21.82 36.72 68 14.90 Shistosomias
is, scabies,
fresh cuts,
high blood
36. Water lettuce
[Oju oro (Yor)]
Pistia stratiotes 21.02 19.00 10 2.02 Skin rashes,
boils, sores,
37. White camwood
leaves [ Oha
211.20 129 39 82.2
38. Yam tuber Dioscorea
7.77 7.52 3 0.25
39. Honey 27.78* 33.47* 21 5.69 Cold, cough,
*Values as mg/ 100 cm
KEY: CV = cyclic voltammetric determination; NBS = N-Bromosuccinimide titrimetric
determination; Yor = Yoruba; Hau = Hausa.
It is pertinent to relate the vitamin C content of these vegetables and food samples to the
alleged curative uses in herbal medicine. Several of these samples are alleged to be useful in the
treatment of sores, cuts, wounds, abscesses, malaria, skin diseases and cold [33]. These medicinal uses
are stated in Table 1. Such samples include amaranth globe (97.49), bitter leaf (32.15), cabbage
(23.05), ginger (11.50), honey (27.78), jute mallow (serrated, 89.94; smooth, 40.21), koko vine
(56.27), lemon grass (9.37), locust bean (73.23), mint leaf (52.75), potato (sweet, 6.15), red pepper
(123.73), roselle calyx (green variety) (27.50), roselle calyx (red variety) (32.14), water leaf (21.82),
water lettuce (21.02). These plants, except ginger, lemon grass and potatoes (sweet) have medium-high
vitamin C content. Potatoes (sweet) are often consumed in larger quantities than vegetables and thus
significant quantities of vitamin C will be present in such menu.
Vitamin C has been reported to be protective and therapeutic in cardiovascular diseases [34-36]
and some of these plants are alleged to be useful as diuretic or antihypertensive [33]. These include
climbing black pepper [leaves (181.19), seeds (14.59)], cucumber (unpeeled, 6.99), lemon grass (9.37),
locust bean (73.23), mint leaf (52.75) and roselle calyx [(green variety) (27.50), (red variety) (32.14)].
Several of these plants have high vitamin C content. Raised blood pressure is a major cause of stroke
and studies have shown that high intake of fruits and vegetables is associated with reduced risk of
Int. J. Electrochem. Sci., Vol. 5, 2010
ischemic stroke [37, 38]. Thus, the plants listed have the potential to reduce high blood pressure and
hence would have preventive activity against stroke.
Vitamin C has also been reported to be protective and therapeutic in cancer [39]. Fluted
pumpkin (129.39) is alleged to be useful in the herbal treatment of cancer while myriantus (15.93) is
alleged to be helpful as an antitumour herbal medicine [33]. While fluted pumpkin leaves are rich in
vitamin C, myriantus leaves will not be considered rich. Thus myrianthus leaves probably contain
other anti-cancer constituents.
Vitamin C is also reported to be protective and therapeutic in eye diseases [40]. Green
amaranth is moderately rich in vitamin C (60.12). It is used as herbal treatment for eye diseases [33,
Vitamin C, functioning as an antioxidant, has been reported to be relevant in the treatment of
male infertility factor [15, 16]. Climbing black pepper (leaves, 181.19, seeds, 14.59) are used in herbal
medicine to treat impotence which is synonymous with male infertility in local terminology.
Thus several plants which are rich in vitamin C appear to have therapeutic values although
there may be no clinical trials to support this observation.
This report further enlarges the database for the vitamin C content in several tropical fruits,
vegetables, seeds and foods. The results presented in this report will provide a suitable guide to the
population in their choice of vegetables with high content of vitamin C. Adequate consumption of the
vegetables with high vitamin C content will result in improved health thereby reducing cardiovascular
diseases, diabetes, eye diseases, infertility and cancers that are prevalent in Africa.
The cyclic voltammetric method can be used in Quality Control laboratories for rapid and
accurate determinations of quantitative values of vitamin C in agricultural samples and in
pharmaceutical preparations.
We wish to express appreciation to Professor Omowunmi Sadik of State University of New York,
Binghamton, USA for her interest and helpful suggestions. We are also grateful to Dr. A. Akintoye of
the vegetable Department, Nigerian Institute of Horticulture Ibadan for identification of vegetable and
food samples.
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... has short life span, takes an average of only 30 -45 days from planting to harvesting (8).Plant quality and freshness is best when harvested in the morning when transpiration is minimal. The leafy produce of this crop is highly perishable start wilting a few hours after harvest (9) The leaf and root extracts are used for treating asthma, fresh cuts, scabies, anemia and high blood pressure (10 ) Cochorus olitorius L (Ewedu) is a fast growing annual herbs up to 4m tall with fibrous stem.The leaves are ovalelancelate to lanceolate 60 to 100mm long and 20 -40 mm wide. Cochorus olitorius grows in tropical and subtropical regions throughout the world. ...
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Vegetables provides nutrients vital for health and maintenance of the body. As good and beneficial vegetables are, it can also be an harbinger for transmission of contamination and bacterial infections when not properly handled especially in the course of buying and selling in the market for consumption. A cross sectional study was conducted between January and March 2022, to assess the level of bacterial contamination of vegetables, this is the basis of the objective of this study. Method: Selected vegetables were purchased from local vendors from market. lt was processed for examination in the Microbiology laboratory where standard cultural techniques was carried out to identify, isolate and characterize the bacterial isolated. Result: Of the 280 vegetables samples examined, 102 (36.4%) were positive for bacteria while 178 (63.6%) had no bacteria isolated. The bacteria pathogens isolated were; Escherichia coli, Staphylococcus aureus, Salmonella species and Proteus mirabilis Conclusion; There was bacterial contamination from the result. The role of Environmental Health Officers to educate and sensitize the local vendors to monitor and ensure vegetables are properly displaced in shelves and provided in hygienic manner will reduce the contaminations and bacterial infection.
... Commonly used methods for the quantitative analysis of AA include absorbance photometry, high-performance liquid chromatography, electrochemical methods, titrimetric methods [7], fluorescence spectroscopy [8], chemiluminescence [9], enzymatic methods [10], capillary electrophoresis [11], etc. Among them, electrochemical technology is widely used because of its advantages such as convenience, low cost, miniaturization and high dynamic range [12][13][14][15]. ...
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The traditional quantitative analysis methods of ascorbic acid (AA), which require expensive equipment, a large amount of samples and professional technicians, are usually complex and time-consuming. A low-cost and high-efficiency AA detection device is reported in this work. It integrates a three-electrode sensor module prepared by screen printing technology, and a microfluidic chip with a finger-actuated micropump peeled from the liquid-crystal display (LCD) 3D printing resin molds. The AA detection process on this device is easy to operate. On-chip detection has been demonstrated to be 2.48 times more sensitive than off-chip detection and requires only a microliter-scale sample volume, which is much smaller than that required in traditional electrochemical methods. Experiments show that the sample and buffer can be fully mixed in the microchannel, which is consistent with the numerical simulation results wherein the mixing efficiency is greater than 90%. Commercially available tablets and beverages are also tested, and the result shows the reliability and accuracy of the device, demonstrating its broad application prospects in the field of point-of-care testing (POCT).
... According to Croteau et al. [1], alkaloids confer some level of resistance to plants against invaders and have high health benefits. Studies have shown that anti-oxidants can inhibit chemical impairment caused by free radicals produced in many ways such as pesticide, organic solvents and environmental pollution [5]. Synthetic antioxidant like butylated hydroxyanisole and butylated hydroxytoluenehave the capacity of increasing the longevity of plant products and are utilized in food industries [6]. ...
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The anti-nutrient compositions of fluted pumpkin leaf grown in three different geoponic media were quantified. These media were white-sand (WS), humus soil (HS) and sawdust (SD). The anti-nutrients composition of matured pumpkin leaf assessed were alkaloids, flavonoids, saponins, hydrogen cyanide, trypsin-inhibitor, oxalate, tannins and phytate. Standard analytical methods were followed in the determination of the anti-nutrient compositions. Phytate, tannin, oxalate, trypsin-inhibitor, hydrogen cyanide, and saponins contents (ppm) in fluted pumpkin leaf grown in WS, HS and SD were 7.131, 8.857 and 8.866; 1.436, 2.127 and 4.348; 3.814, 5.927 and 4.882; 0.959, 2.584 and 1.556; 0.007, 0.001 and 0.002; 4.175, 7.253 and 5.108, respectively while total flavonoids and total alkaloids contents (g/100g) were 7.679, 8.064 and 13.387, and 17.848, 9.077 and 12.445 in that same order. Among the groups of alkaloids, indole/benzypyrole (5.959, 1.059 and 3.885 g/100g) and quinoline (4.493, 4.507 and 5.041 g/100g) were the most abundant while acridine (0.008, 0.009 and 0.011 g/100g) and imidazole (0.001, 0.003 and 0.001 g/100g) were the least in the three treatments. Also, isoflavones (2.321, 3.731 and 5.551 g/100g) and flavan-3-ols (4.648, 3.918 and 7.226 g/100g) were the most concentrated subgroups of flavonoids while anthocyanin was the least (0.083, 0.083 and 0.082 g/100g) for WS, HS and SD, respectively. The study revealed that the bioactive content of T. occidentalis changes depending on the growth medium.
... (Grubben, 2004). The consumption of vegetables in diet has been reported to protect the human body from degenerative diseases and the main protective action of vegetables had been attributed to the antioxidants present in them (Ogunlesi et al., 2010). ...
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All rights are reserved by UIJRT.COM. Abstract-The effects of the characterization of heavy metal in Amaranthus hybridus L, grown on poultry manure and refuse dump compost were assessed in a screen house. Seedlings of A. hybridus were transplanted into various soil treatments: Treatment A, garden soil and river sand in ratio of 3:1, control; B (garden soil, refuse dump compost and river sand in ratio 3:2:1; and C (garden soil, poultry manure and river sand in ratio 3:2:1. Completely randomized design with five experimental units were used. At intervals of 2 weeks for 14 weeks, growth parameters and concentrations of heavy metals in the plant parts at the beginning and end of the experiment were assessed. Data obtained were subjected to ANOVA and means separated using DNMRT at P < 0.05. Treatment C produced the highest mean plant height, number of leaves, leaf area, fresh and dry weight of leaves, stems, roots and seeds, suggesting higher yield over other treatments. Treatment B performed better than A, indicating some improvement in the soil fertility with the application of refuse dump compost. Cadmium and lead in Treatment B were above the FAO/WHO limits for heavy metals in vegetables. Thus, A. hybridus grown with refuse dump compost is unsafe for consumption since they greatly accumulate toxic heavy metals.
... Waterleaf can serve as a part of a weight-loss diet due to its high fiber content, and its leaves is used to treat several diseases, including measles [19]. Also, leaf and root extracts are used for treating asthma, fresh cuts, scabies, anaemia, and high blood pressure (hypertension) [20], as outlined below as: ...
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This study was conducted to analyze the health benefits and medicinal values of four different selected vegetable species (Corchorus olitorius, Melissa officinalis, Occimum gratissimum and Talinum triangulare) in three different families; Malvaceae, Lamiaceae and Talinaceae procured in Serrekunda market for cosmopolitan consumption rate in the Gambia. A qualitative research design is adopted. Leafy vegetables play specific roles and form an important part of human diet that provides a cheap supplement and other source of nutrients such as minerals, vitamins, proteins, etc. to the body. In West Africa, particularly the Gambia, vegetables are vulnerable farm/garden outputs, due to the fact that they are staple food for humans in most areas in which rich sources of carbohydrate are mostly derived from, like any other plants such as cassava and potato, rice and maize, sorghum and millet, scent leaf and nana mint leaf, etc. It is important to observe their necessary condition for their increased and improved production of leafy vegetables due to their high significant photosynthetic capacity productivity as a potential point, resulting in achieving an increase output in crop productivity. They are mostly C4 plants which showed higher photosynthetic strength by suppressing photo-respiration that occur mainly at low atmospheric carbon dioxide concentration, high light, high temperature, drought and salinity than C3 plants. They also have the ability and capability to convert carbon dioxide gas into organic matter more efficiently than the C3 plants. Analyses of data using simple percentage correlation showed that strongly agreed recorded the highest percentage rate of 51.52% from responses of 170 people and disagree recorded the lowest percentage rate of 6.06% from 20 people responses to the questionnaire statement made on item number 8 as “Do you know that Saluyot Spp (Corchorus olitorius) increases sexual libido, fertility and reduces bladder problem”. Chi-square showed the probability level of insignificance at P > 0.05, showed the level of insignificance goodness of fits on the population of sampled vegetable species on environmental unawareness health benefits and its medicinal values in the Gambia, other than the leaves color ratio of 3 green and 1 yellow category, data can also be more than two depending on their phenotypic generational appearance. Efficient harvesting of these different vegetable species and proper awareness to the people on its medicinal value and health benefits brings about a sustainable environmental vegetable gar- den farming in the Gambia. Subject Areas
... The results obtained in this study were higher than as it was reported by Negbenebor et al., (1999), Okonkwo and Ogu (2014) and Ilodibia et al., (2016). Since vitamin C (ascorbic acid) promotes the health of teeth and gums, lungs and bronchia, and joints, aids the purification of blood (Ogunlesi et al., 2010), its (ascorbic acid) presence in the leafy vegetables more especially in African black pepper leaf with the highest vitamin C content suggests that its consumption and use in herbal medicine can prevent common cold and other diseases like prostate cancer (Igile et al., 2013). Uhegbu et al., (2011) reported that Piper guineese contained 7.09u/100g of vitamin A, 5120u/100g of vitamin C and 1.64 u/100g of vitamin E. Meanwhile, Bouba et al., (2012) confirmed Piper guineese contained 9.3g/100g of vitamin A, 2.7g/100g E and 0.9g/100g of vitamin C. Table 4 showed that piper guineese contained six anti-nutrient elements. ...
Conference Paper
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Nigeria paper industry has not reached the optimum performance level expected of it by planners despite the huge money spent on the inputs. This paper examines the problems militating against pulp and paper production in Nigeria and highlights the pathway for leading to complete dependence on importation of paper and paper products. In 2006, the mills were privatized, and, currentlymore sustainability of industrial growth most especially in the pulp and paper industries. and 66.17% in the 1960’s.In 1996, The Nigeria Newsprint Manufacturing Company (NNMC), Oku Iboku alsostopped production 1970s performed optimally except The Nigerian Paper Mill, Jebba in the 1980’s as pulp and paper importation reduced drastically as a result of high capacity utilization in the mills. In 1985 and 1986, capacity utilization in Nigerian Paper Mill was 62.3% in 1960’s arborea, Pinus caribaea,etc. are threatened due to high rate of deforestation and increasing demand of their wood for other promoting optimal pulp and paper capacities locally. Commonly used tree species for pulp and paper production like Gmelina machinery for massive sustainable wood production. Likewise, the use of indigenous wood species and agricultural residues should be establishment of pulp and paper mills in the country before it finally stop production in 1994 due to the high dependence on foreign encouraged for long fiber pulp production. Efforts should further be made for a stable power supply from national grid to ensure the economic purposes. Hence, none of the three primary pulp and paper mills established in the country by government within 1960s to than 500 billion naira is expended on importation of paper products annually. The only and urgent remedy is to put in place Keywords: Forest product,pulp and paper, newsprint, manufacturing, industry
... Members of this genus are mainly perennial herbs and cosmopolitan in distribution. T. triangulare commonly known as waterleaf is grown in the tropics as a leafy vegetable due to its nutritive values (Oguntona, 1998;Ogie-Odia and Oluowo, 2009;Ofusori et al., 2008;Mensah et al., 2008;Ogunlesi et al., 2010). The leaves contain phytochemicals such as flavonoids, alkaloids, saponins and tannins (Ogbonnaya and Chinedum, 2013;Aja et al., 2010;Ukpabi et al., 2013;Swarna and Ravindhran, 2013). ...
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The structure and ontogeny of stomata in Talinum triangulare were examined to determine the developmental pathway of stomata in the leaves. Young leaves at different stages of growth and mature leaves were peeled, bleached in 70% ethanol, stained with alcian blue and examined under the microscope. Clear photo-micrographs were taken with trinocular research microscope (Amscope T340B) fitted with Amcope digital camera. The transitional stage of the stomata was mainly anisocytic in nature but the mature stomata were only paracytic. The ontogeny of the stomata was mesogenous and the plant was amphistomatic and glabrous. The ratio of the stomata index on the adaxial (19.02±1.82) to abaxial (36.08±3.52) layer was 1:2. The anticlinal walls of the mature leaves were wavy on both adaxial and abaxial surfaces and straight in the young leaves. The epidermal cell shapes were irregular on both surfaces but polygonal in the young leaves. The length and width of the stomatal complex, guard cell and the epidermal cells were higher in the adaxial surface than the abaxial surface. The stomatal ontogeny of this species could serve as an important taxonomic tool in delimiting the species.
... [35], which is lower than the values recorded in the present study. Vitamin C values of 6.15 and 4.28 mg/100 g f.w. were reported in [36] and values of 27.7 mg/100 g f.w. were reported in [37]. ...
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Sweet potatoes have multiple uses as food, feed, and in industrial production. They are characterized by their need for high temperatures for optimal development. This study aimed to analyze the quantitative and qualitative aspects of growing sweet potato cultivars in southwest Romania using mulching and non-mulching systems. The effects of mulching on the production of tuberous roots and the contents of total soluble substance, vitamin C, starch, total polyphenols, and antioxidant activity (DPPH) were evaluated in three cultivars with white pulp (the ‘Pumpkin’ and ‘Chestnut’ cultivars) and with orange pulp (the ‘Italian’ cultivar). It was found that mulching with polyethylene film improved the production of sweet potatoes, amounting to 41.42 t/ha in the case of the ‘Italian’ cultivar. Moreover, the effect of mulch induced increases in total soluble substance (16.40%) and starch (16.01%) in the ‘Chestnut’ cultivar, in vitamin C (9.23 mg/100 g d.w.) in the ‘Pumpkin’ cultivar, and in antioxidant activity in the ‘Pumpkin’ (2716.55 µmol AsA/g d.w.) and ‘Chestnut’ cultivars (1131.31 µmol AsA/g d.w.), while the polyphenols in the ‘Italian’ cultivar decreased.
Using Osun State in Nigeria as a case study, the use of indigenous leafy vegetables in health management was investigated. An extensive literature survey was carried out to classify and detail the medicinal use of some indigenous leafy vegetables in South-Western Nigeria followed by a field survey to substantiate the result of the literature survey. A multistage sampling procedure was adopted for the fieldwork. The fieldwork consisted of the collection of ethno-botanical data through well-versed semi-structured interviews, questionnaires, and focused group discussions with key informants including farmers, shepherds, and housewives in five (5) communities. Twelve (12) vegetable species used as medicine, in addition to being eaten as vegetables and belonging to eight (8) families, were encountered in the five communities. Asteraceae had the highest number of species. Relative frequency of citation (RFC) and cultural importance index (CII) were calculated; it showed that Vernonia amygdalina holds a special place among medicinal vegetables in Osun State. The literature survey on the various indigenous leafy vegetables revealed that they have high medicinal value, and the study has given justification to the traditional uses of the plants by the indigenous communities in Osun State.
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Abstract: Green leafy vegetables (GLVs) are a boon to the healthy and safe lifestyle. In terms of daily nutritional needs they are considered an essential element of the diet. GLVs are high in vitamins including beta carotene, ascorbic acid, folic acid, and riboflavin, as well as minerals like iron, calcium, and phosphorus. They also include a wide range of bioactive non-nutritive health-promoting components including antioxidants and phytochemicals, which have health advantages that go beyond basic nutrition. The most plentiful supply of protein, vitamins, and minerals has long been known to be green leafy vegetables (Aletor et al., 2002; Shukla et al., 2006). Leafy vegetables not only provide nutrition but also give variety to an otherwise dull diet. Furthermore, anti-cancer, antibacterial, liver protective, anti-inflammatory, and other effects have been identified for several of the plants. Indigenous people and nomadic peoples employ them as natural healers because of their therapeutic properties. They have alternative taste, pleasing aroma and are used to cure the problem of Iron (Fe) deficiency or anemia and has various health benefit. The Amaranthaceous family includes the bulk of green leafy vegetables. Green vegetables such as spinach, amaranthus, and gogu are known as the "poor man's diet" because they are readily accessible all year at a cheap cost and are less expensive than other vegetables.
In India, various types of underutilized foods are available seasonally but are not utilized to the extent they should be inspite of their high nutritive value. Looking into the prevalence of high level of micronutrient malnutrition among vulnerable section, utilization of underutilized foods can be explored to overcome the nutritional disorders. Practically, there is no information available on the nutritive value of underutilized foods, which may contribute significantly to the nutrient intake of rural population. Thus, an attempt has been made to identify and analyze various underutilized vegetables for their nutrient content from selected regions of south Karnataka. A total of 38 green leafy vegetables have been identified and the iron content of the same ranged between 3.68 to 37.34mg/100g, the highest iron content was observed in Nelabasale greens, Portulaca oleracea (37.34mg). Calcium content ranged from 73 to 400mg/100g. Chilikere greens, Oxalis acetosella (400mg) had maximum calcium content. The highest ascorbic acid content was found in Knol Khol greens, Brassica oleracea.
1. Oxygen is a toxic gas - an introductionto oxygen toxicity and reactive species 2. The chemistry of free radicals and related 'reactive species' 3. Antioxidant defences Endogenous and Diet Derived 4. Cellular responses to oxidative stress: adaptation, damage, repair, senescence and death 5. Measurement of reactive species 6. Reactive species can pose special problems needing special solutions. Some examples. 7. Reactive species can be useful some more examples 8. Reactive species can be poisonous: their role in toxicology 9. Reactive species and disease: fact, fiction or filibuster? 10. Ageing, nutrition, disease, and therapy: A role for antioxidants?
The crude protein contents of ten leafy vegetables commonly eaten by the peasant population of the Cross River State of Nigeria ranged between 17·2% and 28·4% dry matter. The ranges of values for their crude fat, fibre and ash contents were 2·7–8·1%, 8·5–20·9% and 9·7–18·6% dry matter, respectively. The fructose, glucose, sucrose and maltose contents in 70% ethanol extracts of these vegetables were 0·6–1·6%, 0·6–1·8%, 0·8–2·6% and 0·3–2·3% dry matter, respectively. The dry matter in the vegetables ranged between 7·7% and 24·7% of the fresh weight. The high nutritive potentials of these leafy vegetables justify their wide consumption.
It has been found that ascorbic acid (AA) and dehydroascorbic acid (DHAA) can be derivatized to the compounds having a maximum absorption wavelength of 300nm under alkaline conditions, and that derivatization of DHAA is accelerated in the presence of a reducing agent such as sodium borohydride. This reaction has been applied to post-column derivatization in high performance liquid chromatography (HPLC) for the simultaneous determination of AA and DHAA. In this system, AA in the range of 1ng 2μg and DHAA in the range of 2ng 2μg have been determined simultaneously with good reproducibility, C.V 1.5% (n=10).
A simple method for determination of L-ascorbic acid of (1‐50) μg/ml in pure form and pharmaceuticals is described. The rapid procedure is based on the direct visual titration of L-ascorbic acid with ceric ammonium sulphate in the presence of chlorpromazine hydrochloride in a mixture of sulphuric and phosphoric acids as a redox indicator.The relative standard deviation of the method is ±(0.0111706−0.12539). An interference study is carried out for the different acids. Most importantly, the new method is applied for a variety of vitamin c in pharmaceuticals and successful results are achieved. Chlorpromazine hydrochloride is used as a redox indicator in oxidised form (Sulfoxide form) in acid mixture with maximum absorbance at 530 nm, formal redox potential was determined to be 285 mv. All the titrations were followed potentiometrically for comparison.
A high-performance liquid chromatography method was developed for the simultaneous determination of dehydroascrobic, ascorbic, malic, citric, and oxalic acids in fruits, vegetables, and beverages. Separation of these compounds was accomplished by coupling reversed-phase and organic acid columns using 2% KH2PO4 (pH 2.3) as mobile phase with a flow rate of 0.4 mL/min. Detection was performed at 215 and 260 nm using a diode array detector interfaced with portable integrators and a chromatography data system. Selected fresh fruits, vegetables, and commercial orange juices were analyzed using this method.