Efficient Estimation of Ascorbic Acid in Vitamin C Tablets Enabled by Phase-Transfer Strategy

In this paper, we introduced a novel phase-transfer strategy tailored for the efficient batch detection of ascorbic acid in vitamin C tablets. This method entailed the reaction between ascorbic acid and an excess of potassium permanganate. Subsequent reaction of the residual potassium permanganate with sodium oxalate in an acidic medium led to the generation of carbon dioxide. The quantification of the produced carbon dioxide was achieved using headspace GC, enabling the indirect measurement of ascorbic acid. The obtained findings revealed that the headspace method exhibited satisfied precision with a relative standard deviation of less than 2.11% and high sensitivity with a limit of quantitation of 0.27 μmol. These results firmly establish the reliability of this innovative approach for determining ascorbic acid. In addition, the highly automated feature of headspace method significantly enhances the efficiency of batch sample detection and reduces the errors caused by human operation. Thus, the adoption of the transformed phase strategy has demonstrated its effectiveness in assessing ascorbic acid, especially for large-scale sample analysis in industrial applications, owing to its efficiency, precision, and sensitivity.

Phytochemical profile and antioxidant activity of various solvent extracts of two varieties of ginger and garlic

There is limited information on the phytochemical profile and antioxidant activity of ginger and garlic consumed in Uganda. This could have an impact on its widespread use and industrial application. Thus, this study was done to determine the phytochemical profile and antioxidant activity of two varieties of ginger and garlic commonly consumed in Uganda. Fresh ginger rhizomes and garlic cloves of "local" and "hybrid" varieties were acquired from a local food market, washed, grated, and extracted using acetone, ethanol, methanol, and water. Standard techniques were used to determine the phytochemical composition. Total phenolic and flavonoid content were measured using Folin-Ciocalteu and aluminium chloride assays, respectively. Antioxidant activity was determined using the 2, 2-Diphenyl-1-picryl hydrazyl (DPPH) assays. Ginger extracts exhibited significantly higher total phenolic and flavonoid content compared to garlic (p˂0.05). The highest total phenolic and flavonoid content was in ethanol and methanol extracts of local ginger: 1968.49 and 2172.65 mg GAE/100 g; 254.24 and 184.62 mg QE/100 g, respectively. Tannins, alkaloids, saponins, and terpenoids were in varying concentrations in the extracts. Levels of Vitamin C were significantly high in aqueous extracts (p˂0.05), 38.34 and 40.80 AAE/100 g in local and hybrid ginger; 33.65 and 35.24 mg AAE/100 g in local and hybrid garlic, respectively. The free radical scavenging activity of extracts varied depending on concentration, with a strong positive correlation between antioxidant activity and total phenolic and flavonoid content. The half maximal inhibitory concentration (IC50) ranged from 0.16 to 8.93 mg/ml in local ginger, 4.43-6.44 mg/ml in hybrid ginger, 3.93-5.64 mg/ml in local garlic, and 4.44-5.27 mg/ml in hybrid garlic. The best antioxidant activity was exhibited by ethanol extracts of the local ginger. According to the findings, the two varieties of ginger and garlic have strong antioxidant activity due to their different phytochemical compositions, which could make them useful as natural antioxidants in food and medicine applications.

Box–Behnken Design Based Development of UV-Reversed Phase High Performance Liquid Chromatographic Method for Determination of Ascorbic Acid in Tablet Formulations

A simple, sensitive, accurate and inexpensive UV-reversed-phase high-performance liquid chromatographic method was developed for the determination of ascorbic acid in tablet formulations. The method was based on the separation of ascorbic acid using a mobile phase of an acetonitrile-NaH2PO4-H3PO4 buffer solution (pH = 3) (5:95 v/v) with a UV detection wavelength of 245 nm and a flow rate of 0.8 mL min−1 at ambient column temperature. The variables of the proposed method, such as acetonitrile fraction (%), flow rate (mL min−1) and column temperature (°C), were optimized on the peak area by response surface methodology via the Box–Behnken design. The mobile phase was passed isocratically, and the separation of ascorbic acid was performed at the retention time of 4.1 min. A calibration graph was obtained and found to be linear in the concentration range of 10–180 µg mL−1. The method suitability was assessed and an asymmetry factor of 1.15 was obtained. The proposed method was successfully applied for the determination of ascorbic acid in tablet formulations and statistically compared with the results of the reference method. The performance of the proposed method was excellent and in agreement with the reference method. The recovery percentage of the proposed and reference methods was in the range of 99.98–100.04% and showed compliance (100 ± 2%) with regulatory guidelines.

A Simple, Cost-Effective, and Green HPTLC Method for the Estimation of Ascorbic Acid in Solvent and Ultrasound-Assisted Extracts of Phyllanthus emblica, Capsicum annuum, and Psidium guajava

Greener analytical methodologies for the estimation of ascorbic acid (AA) are poorly reported in the literature. Furthermore, the green indexes of the literature’s analytical assays of AA estimation have not been assessed. As a consequence, the aim of this research is to invent and validate a simple, cost-effective, and green reverse-phase “high-performance thin-layer chromatography (HPTLC)” method for the estimating AA in the solvent extracts (SE) and ultrasound-assisted extracts (UAE) of Phyllanthus emblica, Psidium guajava, and Capsicum annuum. The greener mobile phase for AA estimation was a binary mixture of water and ethanol (70:30, v/v). At a wavelength of 265 nm, the detection of AA was carried out. The greener HPTLC technique was linear in the 25–1200 ng/band range. In addition, the method was simple, cost-effective, accurate, precise, robust, sensitive, and green. The amount of AA was highest in the SE and UAE of P. emblica compared to the SE and UAE of P. guajava and C. annuum. The amount of AA in the SE of P. emblica, P. guajava, and C. annuum was found to be 491.16, 168.91, and 144.30 mg/100 g, respectively. However, the amount of AA in the UAE of P. emblica, P. guajava, and C. annuum was found to be 673.02, 218.71, and 199.30 mg/100 g, respectively. Using the “analytical GREEnness (AGREE)” methodology, the greenness index for the developed method was calculated to be 0.88, showing that the developed method has an excellent green profile. When it came to extracting AA, the UAE method outperformed the SE method. These findings suggested that the developed method might be used to estimate the AA in a variety of vegetable crops, plant-based extracts, and commercial formulations. Furthermore, because of the use of greener solvent systems against the commonly utilized hazardous solvent systems for AA determination, this technique is also safe and sustainable.

Evaluation of Bioactive Properties of Lipophilic Fractions of Edible and Non-Edible Parts of Nasturtium officinale (Watercress) in a Model of Human Malignant Melanoma Cells

Watercress is an enriched source of phenethyl isothiocyanate (PEITC), among other phytochemicals, with an antioxidant capacity. The aim of this study was to (i) chemically characterize and (ii) biologically evaluate the profile of the main health-promoting compounds contained in edible (i.e., mixture of leaves and lateral buds) and non-edible (i.e., stems) parts of watercress in an in vitro model of malignant melanoma consisting of human malignant melanoma (A375), non-melanoma (A431) and keratinocyte (HaCaT) cells. The extraction of the main constituents of watercress was performed by subjecting the freeze-dried edible and non-edible samples through different extraction protocols, whereas their concentration was obtained utilizing analytical methodologies. In addition, cell viability was evaluated by the Alamar Blue assay, whereas levels of oxidative stress and apoptosis were determined by commercially available kits. The edible watercress sample contained a higher amount of various nutrients and phytochemicals in the hexane fraction compared to the non-edible one, as evidenced by the presence of PEITC, phenolics, flavonoids, pigments, ascorbic acid, etc. The cytotoxicity potential of the edible watercress sample in the hexane fraction was considerably higher than the non-edible one in A375 cells, whereas A431 and HaCaT cells appeared to be either more resistant or minimally affected, respectively. Finally, levels of oxidative stress and apoptotic induction were increased in both watercress samples, but the magnitude of the induction was much higher in the edible than the non-edible watercress samples. Herein, we provide further evidence documenting the potential development of watercress extracts (including watercress waste by-products) as promising anti-cancer agent(s) against malignant melanoma cells.

Hydrogen peroxide assisted synthesis of sulfur quantum dots for the detection of chromium (VI) and ascorbic acid

Sulfur quantum dots (SQDs), heavy-metal-free quantum dots, are regarded as the next generation promising green nanomaterials compared with traditional heavy-metal-based quantum dots. However, there have been few reports on the synthesis and application of SQDs for analytical detection. Herein, an H₂O₂-assisted top-down method is used to synthesize SQDs. The as-obtained SQDs have good water dispersion, stability, photoluminescence (PL) properties and achieving a quantum yield (QY) to 11%. After adding Cr (VI) in SQDs, the fluorescence intensity decreases base on inner filter effect (IFE). Moreover, Cr (VI) can be reduced to Cr(III) when ascorbic acid (AA) is introduced into the SQDs - Cr (VI) system, accompanying the recovery of the fluorescence intensity. The fluorescence sensor displays high sensitivity and quickly response toward Cr (VI) and AA in a range of 10-120 μmol L^-1 and 20-500 μmol L^-1 with a detection limit of 0.36 μmol L^-1 and 1.21 μmol L^-1, respectively. In addition, the fluorescence sensor has been applied for the determination of Cr (VI) and AA in real samples.

Plum (Prunus rossica Erem.) fruit field and laboratory researces depending on the scion-stock combinations

The results of the field observations and biochemical researches of plum (PrunusrossicaErem.) fruits grown in the garden of intensive type with agrogenic soil in row spacing are presented in the article. The fruits of plum breeds Kubanskaya kometa и Naidena were gathered from the trees grafted on different stocks. The influene of the stock on the trees productivity, the fruit weight and biochemical structure of the plum fruits were studied. Basic chemical analyses, ascorbic acid concentration, antioxidant activity and fruit ash content were determined. The variation limits of the parameters under study depending on the used stock were shown. The best degustation evaluation parameters were found at the combinations of Kubanskaya kometa on stocks OPA-15-2 and Novinka, Naidena on OPA-15-2 (more than 4,5 points). The high positive correlation (r= 0.92) was marked between solutable solids and sugars content.The researches about the stock influence on the plum fruits titratable acidity change we have not found.The correlation between AA and ascorbic acid content in the fruits was determined (r =0.7). The decreasing row of the elements content in the plum fruits ash is the following: K>P>Mg>Ca>Mo>Cu>S>Ni>Fe≈Si>Mn. The proportion of K is from 18.67 (Naidena/ОРА-15-2) to 27.48 (Kubanskaya kometa/Novinka); P from 3.35 (Kubanskaya kometa/seedlings P.cerasifera Ehrh. to 6.39 (Kubanskaya kometa/Novinka), Mg from 1.11 (Nnaidena/ОРА-15-2) to 2.43 (Naidena/seedlings P.cerasifera Ehrh.) and Ca from 0.39 (Naidena/13-11) to 1.85 (Naidena/OPA-15-2) mass % respectively. The proportion of the rest elements is not more than 1 mass %.  Under the OPA-15-2 stock influence the trees productivity and the single fruit weight increased, solutable solids, sugars and ascorbic acid concentration in the fruit in comparison with standard stock by the seedling rootstock of alycha (PrunuscerasiferaEhrh. seedlings). While ingrafting by Novinka stocks the parameters under study decreased.

Invasive Solidago canadensis L. as a resource of valuable biological compounds

The phytochemical characteristics of alien species have not yet been fully studied. Meanwhile, the reserves of their raw materials in the secondary distribution range are very large and can be used as new sources of functional ingredients for food, nutraceuticals, cosmeceuticals, and medicines. Particular attention is attracted by species which have closely related native plants that are included in the official pharmacopeia. Solidago canadensis L. in Slovakia has already formed powerful thickets, and a similar species Solidago virgaurea L. is used as a medicinal plant. The goal of our study is to examine biologically active compounds from leaves and inflorescences of Solidago canadensis collected in some invasive populations along the Nitra river and Gron river. Leaves and inflorescences of 3 populations have been taken for analysis. In addition, we tested herbal tea was made by a traditional procedure using 2 types of fermentation. The following parameters have been understudying: total dry matter, ash and protein content, total lipid, saccharides, vitamin C content, total carotenoid content, amino acids content, elemental analysis, and antioxidant activity. Mean values and variations of these parameters are given in the article. The results demonstrated that S. canadensis can be a valuable raw material resource for many sectors of the economy with the possibility of its wider application in the future.

Increasing of selenium content and qualitative parameters in tomato (Lycopersicon esculentum Mill.) after its foliar application

The effect of genotype and selenium foliar biofortification in the form of an aqueous solution of sodium selenate on the content of total carotenoids, vitamin C, total polyphenols and selenium content in the tomato fruits was studied.  Field experiment was held in the Botanical garden of the Slovak University of Agriculture in 2016. Seven determinant varieties of tomato in the two variants were observed. The results of experiments show that treatment of plants with the dose of Se concentration (150 g Se.ha-1) at the flowering stage significantly increased the total Se content in the in tomato fruits. Foliar application of selenium had a positive effect on the increase of total polyphenol. The influence of Se biofortification on the content of vitamin C and carotenoids was not detected. Selenium foliar fertilization in dosage 150 g.ha-1 is suitable way of tomato fruits enriching in polyphenols, without negative effect on other antioxidants content.

Biochemical composition of sweet cherry (Prynus avium L.) fruit depending on the scion-stock combinations

The results of the field and biochemical researches of sweet cherry Prunus avium L. scion Chermashnaya fruit grown on 8 clonal stocks (Kolt, Moskoviya, Izmaylovskiy, Stepnoy rodnik, AVCH-2, VSL-2, VTS-13, V-5-88) are presented. Trees productivity, the fruit average weight and the stone- fruit weight relation were studied, fruit degustation evaluation was fulfilled and the main biochemical parameters such as soluble solids, sugars sum, ascorbic acid concentration and antioxidant activity were determined. The influence of the stock on the fruit biochemical composition, the trees productivity and the fruit weight was determined. The sweet cherries productivity was 12,5 kg/tree at average, and depending on the stock it varied from 8,3 kg/tree (V-5-88) to 18,6 kg/tree (Izmaylovskiy). The biggest fruit were found on the trees with stocks VSL-2, Izmaylovskiy and AVCH-2. At average the proportion of the stone in the fruit weight was 5.3% with the variation depending on the stock from 5.2% (Kolt) to 5.5% (V-5-88, Stepnoy rodnik). According to the degustation results the fruit of scion Chermashnaya were characterized by the sweet harmonized taste and smell (4.5 points), there were not found either taste deterioration or bitterness on any stock. The best results according to the degustation evaluation by the parameters complex were found at scion Chermashnaya combinations on stocks Izmaylovskiy, VSL-2 and Kolt. The soluble solids content also depended on the stock and varied from 13.9 (Chermashnaya on AVCH-2) to 17.2% (Chermashnaya on Izmaylovskiy) at average value 16.0%. The sugars content in the sweet cherry fruit was within the range from 9.0 to 12.4%. The sugars higher accumulation belonged to the combinations of Chermashmaya on Stepnoy rodnik (11.1%) and Chermashmaya on Izmaylovskiy (12.4%). The ascorbic acid content in the sweet cherry fruit did not exceed 8 mg.100 g-1. Depending on the stock this parameter varied from 5.9 to 9.3 mg.100 g-1. The highest vitamin C content was found in the fruit at the grafting on the stock Stepnoy rodnik, the lowest one - on the stock Moskoviya. The sweet cherry fruit antioxidant activity according to DPPH method was not high and was in the range from 11.8 to 13.8%.

Quantitative and qualitative parameters in Acorn squash cultivar in the conditions of the Slovak Republic

The species Cucurbita pepo includes several types of squashes; in Slovak Republic, well-known and oftenly grown squash types are patisson, zucchini, spaghetti squash, oil pumpkin etc. Several interesting squash types of Cucurbita pepo are grown abroad, including Acorn squash which is well-known mainly in USA. The aim of this study was to evaluate the important quantitative (yield per hectare, average fruit weight) and qualitative (total carotenoids, ascorbic acid, antioxidant activity, total soluble solids) yield parameters of Acorn squash fruits in comparison with patisson which is typical squash type of Cucurbita pepo in Slovak Republic. The field trial was realised in Košice-Šaca in 2016. Within experiment, four cultivars of Acorn type pumpkin were tested (Thelma Sanders; Jet Set; Table Gold; Cream of The Crop). The patisson 'Orfeus' was used as a comparative cultivar for evaluation of individual parameters of Acorn type pumpkin cultivars. Matured pumpkin fruits were harvested on the 7th September 2016. From aspect of yield quantity, Acorn cultivars are appeared as very interesting squash type with good yield potential for growing. The highest yield of squash fruits was found in the cultivar 'Cream of The Crop' (17.8 t.ha-1). In mentioned Acorn cultivar, the yield was higher about 87.4% compared to the tested patisson cultivar 'Orfeus' (9.5 t.ha-1). On the contrary, the average weight of squash fruits was reached in patisson cultivar 'Orfeus' (780.7 g). The qualitative parameters of fruits were expressively influenced by squash cultivar. The content of total carotenoids, ascorbic acid and total soluble solids was markedly higher in all Acorn cultivars, compared to the patisson cultivar 'Orfeus'. The highest content of total carotenoids (26.74 mg.kg-1 fresh weight) and ascorbic acid (238.79 mg.kg-1 f. w.) was found in the squash cultivar 'Table Gold'. The highest content of total soluble solids was determined in the cultivar 'Jet Set' (3.8 °Brix). On the contrary, the highest antioxidant activity (DPPH) was found in the patisson cultivar 'Orfeus' (10.80 %). On the basis of obtained results, it is possible to state that Acorn cultivars are very interesting squash type with promising yield potential for possible growing in conditions of Slovak Republic. In addition, Acorn squashes were expressed by higher content of several nutritional parameters compared to the typical squash type - patisson. Thus, these squashes could be an interesting vegetable for human nutrition.

Impact of nutrition on the quality and quantity of cauliflower florets

Cauliflower (Brassica oleracea var botrytis) as a member of the family Brassicaceae belongs to worldwide popular vegetable with using in all kinds of cuisine. The aim of the work was to find out the effects of nutrition and fertilization (in dependence on the amount of nitrogen) on the yield of florets as well as on selected qualitative characteristics - vitamin C, nitrate and sulforaphane content. Analyses were done by the help of liquid chromatograph (HPLC) with UV detector for separation. The trial was led in Nitra, Slovakia, in 2014 - 2015. Cauliflower variety CHARLOT F1 was selected for testing. Four variants have been examined in the trial: control (without application of fertilizers), N150S80 (application of nitrogen and sulphur at the supply level N: S = 150:80 kg.ha-1), N200S80 and N250S80. Application of nitrogen led to significant increasing of the yields of primary cauliflower florets in case of the dose 200 and 250 kg N.ha-1 (increasing about 87% and 134% compared to control). Applied nitrogen nutrition caused significant nitrates increasing in monitored cauliflower florets in order of the variants: 1 (control) <2 (N = 150 kg.ha-1) <3 (N = 200 kg.ha-1) <4 (N = 250 kg.ha-1), but the highest dosage of nitrates is still under the permissible standard according to Food codex of Slovak republic (700 mg.kg-1 of FM). The influence of differentiated nutrition on sulforaphane content was statistically confirmed in case of the 4th variant in comparison to control, where the decrease about 40% was noticed. Influence of nitrogen fertilizing according to used methodology on vitamin C (AA) content was not statistically confirmed. The nutrient concentration in the curds and stalks of cauliflower varied insignificantly with levels of nitrogen applied.

Changes of vitamin C content in celery and parsley herb after processing

Humans and other primates have lost the ability to synthesize vitamin C and therefore the only source is diet. Vitamin C or ascorbic acid has labile nature, it is removed or destroyed in specific degree immediately after harvest, but storage and post - harvest processing also contribute to its degradation. The aim of work was to determine the vitamin C content in the herb of selected celery and parsley varieties in dependence on chosen postharvest processing and to compare it with fresh herb. There were chosen five bulb forms varieties of celery (Apium graveolens) - Makara, Ilonaa, Hegy Köi, Talar and Diamant. In case of parsley (Petroselinum crispum) there were evaluated one variety of curly parsley, one variety of herb parsley - Petra, and five varieties of root parsley - Lenka, Eagle, Ginate D´Italia, Titana and Arat. Every variety was harvested in three terms, followed by vitamin C content estimation in fresh herb, after drying and after freezing. The content of vitamin C was estimated by HPLC method by the help of liquid chromatograph with UV detector. There was found the significant difference in content of vitamin C in parsley as well as in celery when comparing the fresh herb with herbs after post - harvest processes - drying (by air circulation in laboratory hall) and freezing. After processing of herbs in both observed species the vitamin C content decreased, in case of freezing it was about 65% (celery) and 61% (parsley), after drying about 86% (celery) and 82% (parsley) in comparison with fresh herb. The effect of processing played more important role in influencing of vitamin C content than variety in case of both selected species. For using of celery and parsley not only as culinary herb, but as a notable source of ascorbic acid it is the most important fresh herb intake.

Sweet potato (Ipomoea batatas L.) growing in conditions of southern Slovak republic

The sweet potato (Ipomoea batatas L.) belongs to very important crops from aspect of its world production. It is grown in large areas in Asia, on the contrary, sweet potato production in Europe presents minimal part of its total world rate. The sweet potato is less-known crop, grown only on small area in home gardens in Slovak Republic. Tubers of sweet potato are characterized by anti-diabetic, anti-oxidant and anti-proliferative properties due to the presence of valuable health-promoting components, such as carotenoids or vitamin C. The main objective of study was testing of sweet potato growing in conditions of southern Slovak Republic with focus on quantity and quality of its yield. The field trial was realised on land of the Slovak University of Agriculture in Nitra in 2015. Within trial, effect of cultivar and mulching on the selected quantitative (average tuber weight; yield per plant; yield in t.ha-1) and qualitative (total carotenoids; vitamin C) parameters were tested. One certified cultivar of sweet potato 'Beauregard' was used as a comparative cultivar. Other two cultivars were marked according to the market place at which were purchased and sequentially used for seedling preparation. Tubers of first un-known cultivar were purchased in the Serbian market (marked as 'Serbian'). Tubers of next sweet potato cultivar were purchased on the market in Zagreb (marked as 'Zagrebian'). Outplating of sweet potato seedlings were realised on the 19th May 2015. The sweet potato was grown by hillock system. Each cultivar was planted in two variants (rows): non-mulching (bare soil) and mulching by black non-woven textile. All variants were divided to three replications with 6 plants. Difference between rows was 1.20 m and seedlings were planted in distance of 0.30 m in row. The harvested tubers were classified in two size classes: >150 g (marketable yield) and <150 g (non-marketable yield). Total carotenoid content was determined spectrophotometrically. The vitamin C content was measured chromatographically (HPLC). The highest values of average tuber weight, yield per plant and total yield (t.ha-1) were found in cultivar 'Serbian'. Statistical analysis showed statistically significant difference in all yield quantitative parameters of cultivar 'Serbian' against cultivars 'Beauregard' and 'Zagrebian'. The highest content of total carotenoids was determined in cultivar 'Serbian' (99.52 mg.kg-1 fresh weight) with orange-creme flesh color, followed by cultivar 'Beauregard' (94.78 mg.kg-1) with orange flesh color and cultivar 'Zagrebian' (28.79 mg.kg-1) with yellow-creme flesh color. Differences among all cultivars were showed as statistically significant. The highest vitamin C content was detected in tubers of cultivar 'Serbian' (155.70 mg.kg-1), followed by cultivar 'Beauregard' (154.37 mg.kg-1) and cultivar 'Zagrebian' (146.33 mg.kg-1). Statistical analysis confirmed differences among cultivars as statistically non-significant. The mulching of sweet potato plants had statistically significant impact to all quantitative and qualitative characteristics of sweet potato. The application of black non-woven textile resulted in increase of average tuber weight, tuber yield and vitamin C content in sweet potato tubers. On the contrary, higher total carotenoid content was found in non-mulching variant compared to the variant with mulching.