Organic Acid Analysis in Green Tea Leaves Using High-performance Liquid Chromatography.

Green tea is a popular refreshing drink with several functional properties attributed to its bioactive compounds. The bioactive content and composition vary with several factors. Several advances in chromatographic studies have facilitated the study of chemical composition of green tea leaves; however, the content of organic acids, particularly quinic acid, has not been explored fully. Therefore, changes in the content of organic acids, including quinic acid, in green tea leaves, were investigated in this study. All the studied varieties contained large amounts of quinic and oxalic acids. Kukicha and Matcha contained the highest and lowest amounts of quinic acid, respectively. Furthermore, high-grade Matcha had a significantly lower quinic acid content than low-grade Matcha. The Asatsuyu sample had the lowest quinic acid content in 2018 and 2019 compared with the other green tea varieties. The content of quinic acid increased with maturity, but that of oxalic, malic, succinic, and citric acids decreased after a slight increase. Shading cultivation in Saeakari significantly lowered the quinic acid content and slightly increased the content of malic, citric, and oxalic acids. Malic acid and citric acid content in Yabukita changed with sunrise and sunset, but that of other organic acids did not show any considerable change. These results show that using an appropriate plucking time could lead to further improvement in the quality of green tea leaves. Overall, green tea is a good source of quinic acid, which will attract attention in future functional research on this drink.

Isolation, chemical characterization and antioxidant activity of Prunus spinosa L. fruit phenolic polysaccharide-proteins.

Wild blackthorn fruits are a slightly explored area and their use is negligible, although they show many therapeutic effects. Polysaccharide complexes were solubilized from ripe Prunus spinosa L. fruits by sequential extraction with water (cold and hot), oxalate, ammonia, and sodium hydroxide solutions. The extracted fractions were rich in carbohydrates, phenolics, and proteins, indicating the presence of complexes of these compounds. It was found that most of the material was released with 5% KOH and hot water. The aqueous fractions had a high molecular weight and also polydispersity index, while the other fractions had low molecular weight. Based on the monosaccharide composition, three groups of fractions were observed. The aqueous and oxalate fractions represent highly esterified pectin material, ammonia extraction provided a mixture of de-esterified pectin and hemicelluloses, and alkaline isolates were rich in arabinogalactan and hemicelluloses. Antioxidant activity tests revealed significant effects of blackthorn samples, alkali-extracted fractions at concentrations of 0.02 and 0.05 mg/mL achieved DPPH radical scavenging comparable to that of vitamin C. Most samples achieved maximum activity comparable to vitamin C at a concentration of 0.1 mg/mL. An analogous effect was also found by the FRAP test, all fractions had a significant reducing capacity at a concentration of 0.05 mg/mL, but only the alkaline fractions reached almost vitamin C level. Preliminary results may support interest in these "undiscovered" natural fruits as a rich source of natural antioxidants.

Effect of Black Tea Consumption on Urinary Risk Factors for Kidney Stone Formation.

Copious fluid intake is the most essential nutritional measure in the treatment of urolithiasis, and is suggested to be a protective factor in the primary prevention of urinary stone formation. Although the intake of black tea contributes to daily fluid intake, the high oxalate content could outweigh the beneficial effect of urine dilution. The present study investigated the effect of black tea consumption on urinary risk factors for kidney stone formation. Ten healthy men received a standardized diet for a period of ten days. Subjects consumed 1.5 L/day of fruit tea (0 mg/day oxalate) during the 5-day control phase, which was replaced by 1.5 L/day of black tea (86 mg/day oxalate) during the 5-day test phase. Fractional and 24-h urines were obtained. The intake of black tea did not significantly alter 24-h urinary oxalate excretion. Urinary citrate, an important inhibitor of calcium stone formation, increased significantly, while the relative supersaturation of calcium oxalate, uric acid, and struvite remained unchanged. No significantly increased risk for kidney stone formation could be derived from the ingestion of black tea in normal subjects. Further research is needed to evaluate the impact of black tea consumption in kidney stone patients with intestinal hyperabsorption of oxalate.

Quality Assessment of Wild and Cultivated Green Tea from Different Regions of China.

Natural products have always enjoyed great popularity among consumers. Wild tea is an interesting alternative to tea from intensive plantations. The term "wild tea" is applied to many different varieties of tea, the most desirable and valued of which are native or indigenous tea plants. Special pro-health properties of wild tea are attributed to the natural conditions in which it grows. However, there are no complex studies that describe quality and health indicators of wild tea. The aim of this research was to evaluate the quality of wild and cultivated green tea from different regions of China: Wuzhishan, Baisha, Kunlushan, and Pu'Er. The assessment was carried out by verifying the concentration of selected chemical components in tea and relating it to the health risks they may pose, as well as to the nutritional requirements of adults. Wild tea was characterized by higher micronutrient concentration. The analyzed teas can constitute a valuable source of Mn in the diet. A higher concentration of nitrates and oxalates in cultivated tea can be associated with fertilizer use. The analyzed cultivated tea was a better source of antioxidants with a higher concentration of caffeine. There were no indications of health risks for wild or cultivated teas.

Impact of Phyllantus niruri and Lactobacillus amylovorus SGL 14 in a mouse model of dietary hyperoxaluria.

Hyperoxaluria is a pathological condition which affects long-term health of kidneys. The present study evaluates the impact of the combination of Lactobacillus amylovorus SGL 14 and the plant extract Phyllantus niruri (namely Phyllantin 14™) on dietary hyperoxaluria. Safety and efficacy of Phyllantin 14 have been evaluated in vivo. Mice C57BL6 fed a high-oxalate diet were compared to mice fed the same diet administered with Phyllantin 14 by gavage for 6 weeks. Control mice were fed a standard diet without oxalate. No adverse effects were associated to Phyllantin 14 supplementation, supporting its safety. Mice fed a high-oxalate diet developed significant hyperoxaluria and those administered with Phyllantin 14 showed a reduced level of urinary oxalate and a lower oxalate-to-creatinine ratio. Soluble and insoluble caecal oxalate were significantly lower in treated group, a finding in agreement with the colonisation study, i.e. mice were colonised with SGL 14 after 3 weeks. Microbiota analysis demonstrated that both oxalate diet and Phyllantin 14 can differently modulate the microbiota. In conclusion, our findings suggest that Phyllantin 14 supplementation represents a potential supportive approach for reducing urinary oxalate and/or for enhancing the efficacy of existing treatments.

Is There Such a Thing as "Anti-Nutrients"? A Narrative Review of Perceived Problematic Plant Compounds.

Plant-based diets are associated with reduced risk of lifestyle-induced chronic diseases. The thousands of phytochemicals they contain are implicated in cellular-based mechanisms to promote antioxidant defense and reduce inflammation. While recommendations encourage the intake of fruits and vegetables, most people fall short of their target daily intake. Despite the need to increase plant-food consumption, there have been some concerns raised about whether they are beneficial because of the various 'anti-nutrient' compounds they contain. Some of these anti-nutrients that have been called into question included lectins, oxalates, goitrogens, phytoestrogens, phytates, and tannins. As a result, there may be select individuals with specific health conditions who elect to decrease their plant food intake despite potential benefits. The purpose of this narrative review is to examine the science of these 'anti-nutrients' and weigh the evidence of whether these compounds pose an actual health threat.

The effects of extraction techniques and quantitative determination of oxalates in Nerium oleander and feeds.

Shrubs represent the most affordable and accessible form of feed that livestock can rely on to acquire both essential and non-essential elements of life. In addition to their inherent toxins, they contain endogenous substances commonly referred to as 'antinutritive factors' (ANFs) that often interfere with the utilisation of nutrients. Their abundance may lead to severe clinical trauma. Hence, the objective of the study was to investigate the effects of different extraction techniques on Nerium oleander L. and animal feeds as well as to quantify oxalates. Organic (hexane, acetone and methanol) sequential and aqueous (infusion and decoction) extractions were explored. Qualitative and quantitative analyses were conducted to determine the presence of various phytochemicals and oxalate contents as putative ANFs, respectively. The results showed higher extraction yields of 22.6% and 43.1% in the decoction and infusion of N. oleander, respectively. The quantification methods were validated for linearity, accuracy and precision. Oxalate contents of 6.76 ± 0.245 (0.65%) mg/g and 5.74 ± 0.236 mg/g dry weight (0.55%) were obtained in N. oleander and feeds, respectively. This difference was statistically significant with p < 0.05. Percentage recoveries of 98.5 (percent relative standard deviation [% RSD] = 2.3), 85.7 (% RSD = 1.03) and 80.3 (% RSD = 1.22) at 76%, 95% and 112% fortifications were obtained, respectively. Relative standard deviation for precision was 0.99% and 1.13% at 0.33 mg and 0.39 mg fortifications, respectively, while reproducibility showed 2.21% RSD. Therefore, these methods can be used to provide a valuable basis for qualitative determination of ANFs, particularly in shrub foliage.

Ascorbic acid-induced oxalate nephropathy: a case report and discussion of pathologic mechanisms.

Oxalate nephropathy is associated with hereditary hyperoxaluria, Crohn disease, and previous gastric or intestinal surgery, especially in the setting of increased oxalate intake or ethylene glycol ingestion. We present a patient whose intake of vitamin C supplements (2 g/day), exacerbated by predisposing factors of prior small bowel obstruction and resection, and benign prostate hyperplasia (BPH), resulted in acute kidney injury due to oxalate nephropathy. We review past reports of vitamin C-induced oxalate nephropathy and discuss the underlying precipitating factors.

Does green tea consumption increase urinary oxalate excretion? Results of a prospective trial in healthy men.

OBJECTIVE: To investigate the impact of green tea on urinary oxalate excretion in healthy male volunteers. MATERIALS AND METHODS: The oxalate concentrations after different brewing times (2-60 min) of different qualities (2-8 g) of green tea were measured in in vitro experiment. In in vivo experiment, the effects on urine composition were assessed in 12 healthy men with an age of 24-29 years. Each subject was requested to collect two 24-h urine samples under normal dietary conditions. Green tea prepared from tea bags containing 2 g of tea leafs was consumed by the subjects for 7 consecutive days, and 24-h urine samples were collected and analyzed on days 6 and 7. After 3-week washout interval, all subjects consumed green tea containing 4 g of leaf tea for another 7 consecutive days. Two 24-h urine samples were collected on the last 2 days. Urine volume, pH, calcium, magnesium, sodium, phosphate, potassium, chloride, citrate, oxalate, urate and creatinine were measured. RESULTS: In the in vitro experiments, oxalate in solution increased with brewing time (p < 0.05) and tea quality (p < 0.05). In the in vivo experiment, 24-h urinary oxalate increased significantly (0.24 ± 0.09 mmol to 0.32 ± 0.13 mmol, p = 0.045) when tea was prepared from 2-g bags of green leaf tea. Consumption of green tea containing 4 g of leaf tea resulted in 24-h urinary oxalate increase (0.25 ± 0.25 mmol to 0.34 ± 0.22 mmol, p = 0.041). CONCLUSIONS: In vitro studies showed that there was a gradual increase in solution concentrations of oxalate that was associated with increased brewing time and increased quality of green tea. Studies in normal men showed that green tea consumption was associated with increased urinary exertion of oxalate.

Determination of Oxalate Content in Herbal Remedies and Dietary Supplements Based on Plant Extracts.

Lifestyle, especially diet, is a prominent risk factor that affects the formation of calcium oxalate stones. Urinary oxalate excretion is directly related to the amount of oral intake and intestinal absorption rate of oxalate. This work evaluated the possibility of increasing oxalate ingestion, which could lead to secondary hyperoxaluria, associated with the intake of herbal remedies and dietary supplements containing plant extracts. A wide variety of 17 commercially available drugs and dietary supplements were analyzed using ion chromatography. The results showed remarkable differences in oxalate contents of the extracts. Total oxalate concentrations ranged from 0.03 to 2.2 mg/g in solid samples and from 0.005 to 0.073 mg/mL in liquid samples. The selected herbal remedies and dietary supplements containing plant extracts represent only a low risk for calcium oxalate stone formers, if the recommended daily dose is not exceeded.

Oxalate contents of commonly used Chinese medicinal herbs.

OBJECTIVE: To assess the total and soluble oxalate contents of commonly used Chinese medicinal herbs. METHODS: Twenty-two Chinese medicinal herbs were extracted in both acid and water prior to determination of total and soluble oxalate, respectively. Oxalate was assayed in herbal extracts using a well-established enzymatic procedure. RESULTS: Among the 22 medicinal herbs, there was significant variation in oxalate content; Houttuynia cordata contained the highest amount of soluble oxalate (2146 mg/100 g) and Selaginella doederleinii contained the lowest amount (71 mg/ 100 g). CONCLUSION: The results indicated that different Chinese medicinal herbs, even from the same family, contain significantly different amounts of oxalate. In susceptible individuals, the use of medicinal herbs with the highest oxalate contents could increase risk of kidney stone formation.

Antilithiatic Activity of phlorotannin rich extract of Sarghassum Wightii on Calcium Oxalate Urolithiais - InVitro and In Vivo Evaluation.

PURPOSE: Urolithiasis is a common urological disorder responsible for serious human affliction and cost to the society with a high recurrence rate. The aim of the present study was to systematically evaluate the phlorotannin rich extract of Sargassum wightii using suitable in vitro and in vivo models to provide scientific evidence for its antilithiatic activity. MATERIALS AND METHODS: To explore the effect of Sargassum wightii on calcium oxalate crystallization, in vitro assays like crystal nucleation, aggregation and crystal growth were performed. Calcium oxalate urolithiasis was induced in male Sprague dawley rats using a combination of gentamicin and calculi producing diet (5% ammonium oxalate and rat pellet feed). The biochemical parameters like calcium, oxalate, magnesium, phosphate, sodium and potassium were evaluated in urine, serum and kidney homogenates. Histopathological studies were also done to confirm the biochemical findings. RESULTS: The yield of Sargassum wightii extract was found to be 74.5 gm/kg and confirmed by quantitative analysis. In vitro experiments with Sargassum wightii showed concentration dependent inhibition of calcium oxalate nucleation, aggregation and growth supported by SEM analysis. In the in vivo model, Sargassum wightii reduced both calcium and oxalate supersaturation in urine, serum and deposition in the kidney. The biochemical results were supported by histopathological studies. CONCLUSION: The findings of the present study suggest that Sargassum wightii has the ability to prevent nucleation, aggregation and growth of calcium oxalate crystals. Sargassum wightii has better preventive effect on calcium oxalate stone formation indicating its strong potential to develop as a therapeutic option to prevent recurrence of urolithiasis.

Antilithiatic Activity of phlorotannin rich extract of Sarghassum Wightii on Calcium Oxalate Urolithiais ­ In Vitro and In VivoEvaluation

Urolithiasis is a common urological disorder responsible for serious human affliction and cost to the society with a high recurrence rate. The aim of the present study was to systematically evaluate the phlorotannin rich extract of Sargassum wightii using suitable in vitro and in vivo models to provide scientific evidence for its antilithiatic activity.

Effect of delayed harvesting and pre-treatment methods on the antinutritional contents of trifoliate yam flour.

Effects of delayed harvesting and pre-treatment methods on the anti-nutritional contents of trifoliate yam flour were examined. Trifoliate yam tubers were washed, peeled, sliced and subjected to pre-treatment methods, such as soaking, pre-cooking and blanching/soaking. The phenols, phytate, oxalate, tannin and alkaloid profiles of the flours were evaluated and the values of phenols, tannin, oxalate and phytate contents were 0.02-0.32, 0.04-0.53, 0.11-4.32 and 0.20-1.05mg/100g, respectively. The predominant alkaloids in trifoliate yam flour were dioscorine and dihydrodioscorine. The white trifoliate yam flour had higher levels of anti-nutrients than the yellow trifoliate yam flour. Alkaloid contents of trifoliate yam flour increased slightly with delayed harvesting periods. Blanching/soaking method drastically reduced the anti-nutrient contents of trifoliate yam flour than other methods.

Nutrient composition of Cirina forda (Westwood)-enriched complementary foods.

BACKGROUND/AIMS: Dried Cirina forda (Westwood) larva is widely marketed, cheap, and commonly consumed in Southwestern Nigeria. Its powder was used in enriching two commonly used complementary food staples (maize and sorghum) as a source of protein and essential micronutrients in complementary foods for infants and young children. METHODS: Samples of soaked and dried sorghum and maize flours and C. forda powder were prepared, and C. forda powder was added to the dried soaked maize and sorghum flours at 5, 10, and 15% (w/w) inclusion levels and analyzed for proximate, mineral, and antinutrient compositions using standard methods of AOAC. RESULTS: One hundred grams of C. forda larva contained 52.6 g of protein, 16.8 g of lipids, 2.6 g of ash, 268.67 mg of calcium, 5.64 mg of iron, and 15.00 mg of zinc, and yielded 458.40 kcal energy with 4.40 mg of trypsin inhibitor. Sorghum and maize flours contained 9.2 and 8.3 g of protein, respectively. Addition of C. forda at 5, 10, and 15% levels to fermented sorghum and maize flours significantly increased both micro- and macronutrients of the complementary foods (p < 0.05), and the nutrient density and trypsin inhibitor increased with the inclusion level (p < 0.05). CONCLUSION: The trypsin inhibitor level was very low and cannot cause protein malabsorption. C. forda can serve as a good source of nutrients such as protein, fat, calcium, phosphorus, iron, and zinc in formulating nutrient-dense complementary foods.

The impact of Ca2+ combination with organic acids on green tea infusions.

The effect of Ca(2+) in brewing water on the organic acid content, turbidity, and formation of tea cream and sediment in green tea infusions was studied. When the Ca(2+) concentration of the brewing water was >40 mg L(-1), the green tea infusion became more turbid. The turbidity of the tea infusion was highly negatively correlated with the contents of oxalic acid (R=-0.89, p<0.01), quinic acid (R=-0.90, p<0.01) and tartaric acid (R=-0.82, p<0.01). Oxalic acid on its own interacted with Ca(2+) at low concentrations, whereas polyphenols and protein did not. In conclusion, Ca(2+) in brewing water influences the quality of a tea infusion by inducing tea cream and sediment formation from combination of Ca(2+) and organic acids, such as oxalic acid, quinic acid and tartaric acid. Ca(2+) and oxalate are the main metal ion and anion, respectively, involved in tea cream and sediment formation on tea infusion cooling or concentrating.

Effect of different brewing times on soluble oxalate content of loose-packed black teas and tea bags.

Because of the postulated role of increased dietary oxalate intake in calcium oxalate stone formation, the effect of different brewing times on soluble oxalate contents of loose-packed black tea and tea bags was studied. The oxalate content of 25 different samples of loose-packed black teas after brewing at 5, 10, 15, 30, and 60 min and of ten brands of tea bags after infusion for 1, 2, 3, 4, and 5 min was measured by enzymatic assay. The oxalate concentration resulting from different brewing times ranged from 4.3 to 6.2 mg/240 ml for loose-packed black teas and from 2.7 to 4.8 mg/240 ml for tea bags. There was a stepwise increase in oxalate concentration associated with increased brewing times.