Development of a Simultaneous Normal-Phase HPLC Analysis of Lignans, Tocopherols, Phytosterols, and Squalene in Sesame Oil Samples

The objective of this study was to develop a simultaneous analytical method for the determination of lignans, tocols, phytosterols, and squalene using high-performance liquid chromatography coupled with a diode array and fluorescence detector (HPLC-DAD-FLD). The method employed a VertisepTM UPS silica HPLC column (4.6 × 250 mm, 5 µm) with a mobile phase mixture of n-hexane/tetrahydrofuran/2-propanol. This approach enabled the simultaneous analysis of ten compounds within 22 min. The linear correlation (R2) exceeded 0.9901. The limit of detection (LOD) and limit of quantitation (LOQ) were up to 0.43 µg mL-1 for lignans and tocopherols and up to 326.23 µg mL-1 for phytosterol and squalene. The precision and accuracy of the intra-day and inter-day variation were less than 1.09 and 3.32% relative standard deviations (RSDs). Furthermore, the developed method was applied for the analysis of targeted compounds in twenty-eight sesame oil samples (1775-8965 µg g-1 total lignans, 29.7-687.9 µg g-1 total tocopherols, 2640-9500 µg g-1 phytosterol, and 245-4030 µg g-1 squalene). The HPLC method that has been developed was proven to be a reliable and effective tool for the determination of those functional compounds among sesame oil samples.

Bioactive Constituents in Cold-Pressed Plant Oils: Their Structure, Bioactivity and Chromatographic Analysis

Cold-pressed oils are oils prepared from pressing plant materials with a screw or hydraulic press, yielding oils with little contamination of harmful chemicals and high content of nutrients and functional constituents. Cold-pressed oils have gained increasing recognition as food supplements for preventing and ameliorating body deterioration due to ageing and the progression of lifestyle diseases or non-communicable diseases. This article aimed to review their structure, bioactivity, and chromatographic analysis of the mostly found functional compounds in cold-pressed oils, including phytosterols, carotenoids, tocols (tocopherols and tocotrienols), phenolic compounds (flavonoids, phenolic acids, tannins, stilbenes, and lignans), and squalene.

Mineral elements and their relation to anthocyanin content in pigmented rice plants using definitive screening design and self-organizing maps

BACKGROUND

Mineral elements are nutrients required by an organism to perform functions necessary for survival. Stress-induced metabolism following nutritional stress has been reported to increase levels of anthocyanin. However, the role of mineral elements commonly found in soil and their contribution to the accumulation of anthocyanin content in rice plants is uncertain.

RESULT

Amongst the ten mineral elements investigated, the cultivation of rice plants in clean sand showed that the Mg-, Se-, and Cu-treated plants had the highest accumulated anthocyanin content in the leaves, whereas B, Cr, and Se had the greatest effect on grains. Yield component data showed major positive effects from Mg, Cr, and B. The interaction of Zn*Se and Mg*Cu positively affected the anthocyanin content in grains. The self-organizing map indicated that the total anthocyanin content was relatively proportional to the concentration of Mn, B, and Cr, but disproportional to that of Se. However, rice plants with added Fe produced the smallest amount of total anthocyanin content, less than the control, in the four stages of rice growth.

CONCLUSION

The appropriate concentrations of mineral elements in soil could promote the proliferation of anthocyanin content in rice plants and grains. © 2023 Society of Chemical Industry.

Optimization of Vitamin E Extraction from Rice Bran Oil Deodorizer Distillate using Response Surface Methodology

Rice bran oil deodorizer distillate (RBODD) is the low valuable secondary product of refinery rice bran oil. However, RBODD contains bioactive compounds such as vitamin E, gamma-oryzanols, and phytosterols. To increase value of vitamin E obtained from underutilized product, tocopherols and tocotrienols were extracted from RBODD using ethanol followed by a freezing step. The response surface method (RSM) is known as a potential tool for optimizing processing parameters in order to save time, energy, and chemical material. In current study, vitamin E extract (VEE) was extracted using ethanol and response surface method (RSM) was employed to investigate the optimum condition. The ratio of RBODD: ethanol (1:5, 1:10, and 1:15) and the incubation temperature (0, -20, and -40℃) of vitamin E extraction were used to design the experiment using a central composite design (CCD). Once the optimization process was completed, the RSM was executed using the following 5 responses simultaneously: VEET3, VEEToc, VEETot, RecoveryVEE, and YieldVEE. Results showed that values of each parameter were VEET3 (10.69-89.60 mg/g), VEEToc (2.85-23.37 mg/g), VEETot (13.53-112.97mg/g), RecoveryVEE (16.15-134.76%), and YieldVEE (12.64-44.48%). All model predictions were significant (p-value < 0.05), with non-significant lack of fit (> 0.05). In addition, the values of R2 and R2(Adj) of model were in the range of 0.922-0.988 and 0.893-0.982, respectively. According to these findings, response values were associated with RBODD:ethanol ratio and the incubation temperature. The ratio 1:9.5 (RBODD: Ethanol) and incubation temperature at -26.5 ℃ provided the optimal condition for vitamin E extraction from RBODD. At this optimum condition, it was determined that the predicted responses for VEET3, VEEToc, VEETot, RecoveryVEE, and YieldVEE were 81.87 mg/g, 23.70 mg/g, 103.64 mg/g, 123.63 %, and 20.05%, respectively. The obtained product with high content of tocopherol and tocotrienol can be used as ingredient in food as well as pharmaceutical applications.

Influence of black rice (Oryza sativa L.) bran derived anthocyanin-extract on growth rate, immunological response, and immune-antioxidant gene expression in Nile tilapia (Oreochromis niloticus) cultivated in a biofloc system

This study investigated the effects of dietary supplementation with anthocyanin extracted from black rice bran (AR) on the growth rate, immunological response, and expression of immune and antioxidant genes in Nile tilapia raised in an indoor biofloc system. A total of 300 Nile tilapia fingerlings (15.14 ± 0.032 g) were maintained in 150 L tanks and acclimatized for two weeks. Five experimental AR diets (0, 1, 2, 4, and 8 g kg^-1) with various anthocyanin doses were used to feed the fish. We observed that the growth and feed utilization of fish fed with different dietary AR levels increased significantly after eight weeks (p < 0.05). In addition, the serum immunity of fish fed AR diets was much greater than that of those fed non-AR diets (p < 0.05). However, there were little or no difference in between fish fed AR enriched diets and the control AR-free diet (p > 0.05). After eight weeks, fish fed AR-supplemented diets had significantly higher mRNA transcript levels in immune (interleukin [IL]-1, IL-8, and liposaccharide-binding protein [LBP]) and antioxidant (glutathione transferase-alpha [GST-α] and glutathione reductase [GSR]) genes compared to control fish fed the AR-free diet, with the greatest enhancement of mRNA transcript levels (in the case of IL-8 by up to about 5.8-fold) in the 4 g kg^-1 AR diet. These findings suggest that dietary inclusion of AR extract from black rice bran at 4-8 g kg^-1 could function as a herbal immunostimulant to enhance growth performance, feed consumption, and immunity in Nile tilapia.

Microwave treatment of rice bran and its effect on phytochemical content and antioxidant activity

An alternative approach for rice bran stabilization is microwave treatment. However, the effects of the microwave treatment on the contents of bioactive compounds and antioxidant activities of the rice bran have rarely been reported in detail. In this study, microwave pretreatment (130-880 W for 0.5-5.0 min) of rice bran was proposed where the antioxidant activity, total flavonoids, and total phenolic contents were determined using UV-Vis spectrometry. Tocols, γ-oryzanols, squalene, phytosterols and phenolic compounds were quantified using high-performance liquid chromatography. The results showed an increase in the antioxidant activity (0.5 folds), total phenolic contents (1.3 folds), total flavonoid contents (0.9 folds), total tocols (2.6 folds), total γ-oryzanols (1.6 folds), and total phytosterols (1.4 folds). Phytochemicals were enhanced, especially trans-p-coumaric acid (10.3 folds) and kaempferol (8.6 folds). The microwave treatment at 440 W for 2.5 min provided the best contents of the bioactive compounds and antioxidant activity. This work revealed the microwave treatment as a potential tool for stabilizing rice bran and increasing the usability of its phytochemicals, which applies to several industries concerning the use of rice bran as an ingredient.

Smartphone digital image colorimetric determination of the total monomeric anthocyanin content in black rice via the pH differential method

In this research, the pH differential method was explored for the first time using a mobile phone as a detector, replacing UV-Vis spectrophotometry. A smartphone digital image colorimetric (SDIC) system was developed for the determination of the total monomeric anthocyanin content in black rice grains using colour values. The change in colour of anthocyanin cyanidin-3-glucoside (C3G) at pH 1.0 and pH 4.5 was investigated and described through colour model systems (RGB and CIELAB). Under optimum conditions, the quantitative method based on the chroma difference, was able to quantify the total amount of monomeric anthocyanins with a linear correlation (R² = 0.989) to that of UV-Vis spectrophotometry and high performance liquid chromatography (HPLC) (reference method). The SDIC system displayed good precision (≤1.88% RSD) and a low detection limit (2.2 ± 0.1 μg g^-1). The validated results demonstrated that the developed method was a cost-effective alternative for the quantitation of anthocyanins. In addition, the effect of six mineral elements on black rice cultivation was investigated. The results showed that the addition of the Ca fertiliser resulted in black rice grains with an anthocyanin content 2-fold higher than that of the control with a significant difference (p < 0.05).

GC-MS and HPLC-DAD analysis of fatty acid profile and functional phytochemicals in fifty cold-pressed plant oils in Thailand

Cold-pressed oil is one of the healthiest plant extracts, but its use is limited only in some kinds of plants. Therefore, we aimed to investigate some potential cold-pressed oils with attractive fatty acid profiles and high amounts of functional phytochemicals. Fifty cold-pressed plant oils were prepared from various plant materials in Thailand, in which some of them were from uncommon or unattended plant materials. The oils included were nut oils (n = 9), pseudo-cereal oils (n = 9), legume oils (n = 3), amaranth oils (n = 3), marrow seed oils (n = 8), cruciferous seed oils (n = 7), and leafy green seed oils (n = 11). Gas-chromatography mass-spectrometry (GC-MS) and high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD) were employed to analyze fatty acid profile and five functional phytochemicals (e.g., phytosterols, cholecalciferol, and squalene). Saturated fatty acids were detected around 7.87-36.04%, monounsaturated fatty acids 10.17-80.25%, and polyunsaturated fatty acids nondetectable (ND)-78.25%, phytosterols 663-15123 μg g-1, squalene 265-5979 μg g-1, and cholecalciferol ND-1287.75 μg g-1. The study showed chemical characteristic of the analyzed oils: some contained good fatty acid composition and some were rich in functional phytochemical content. Among the obtained oils, marrow seed oils are a good source of phytosterol, cholecalciferol, and linoleic acid. Pseudo-cereal oils are rich in squalene and linolenic acid. Legume oils are rich in phytosterols and oleic acid. Besides, principal component analysis (PCA) was applied to identify the significance of oils that share compositional similarity (e.g., the samples from pseudo-cereal oil were found on the lower side of the PCA space, which separated them from marrow and leafy green seed oils distributed on the upper part of the plot). In summary, the qualitative and quantitative data would provide a good foundation for further application or selection of those plant oils for health purposes.

Simultaneous determination of tocols, γ-oryzanols, phytosterols, squalene, cholecalciferol and phylloquinone in rice bran and vegetable oil samples

In this study, a simultaneous analytical method of tocols, γ-oryzanols, phytosterols, squalene, cholecalciferol and phylloquinone were developed using HPLC-DAD-FLD. The developed method allowed the quantification of 18 compounds in 30 min. Method validation showed linearity of calibration curves (α = 0.05). RSD of intra-day, inter-day and inter-laboratory precision were less than 4.88%. The limit of detections (LODs) and limit of quantifications (LOQs) were low (0.009-2.166 μg g^-1) with recoveries around 96.0-102.9%. Results derived from the established method demonstrated a wide variation of detected compounds in rice bran and vegetable oil samples (22.4-1774.6 μg g^-1 tocols, ND-26484 μg g^-1 γ-oryzanols, ND-12655 μg g^-1 phytosterols, ND-3189 μg g^-1 squalene, ND-105.3 μg g^-1 cholecalciferol, and ND-54.4 μg g^-1 phylloquinone). Thus, the developed HPLC-DAD-FLD method is a powerful analytical tool for the above mentioned compounds useful in food and pharmaceutical application.

Some Strategies for Utilization of Rice Bran Functional Lipids and Phytochemicals

Rice bran contains a great amount of functional lipids and phytochemicals including γ-oryzanols, tocotrienols, and tocopherols. However, utilization of those compounds is limited and needs some proven guidelines for better implementation. We introduce some effective strategies for the utilization of rice functional lipids, including an introduction of pigmented rice varieties for better bioactive compounds, biofortification of rice tocotrienols, plasma technology for improving rice phytochemicals, supercritical CO₂ extraction of high quality rice bran oil, and an example on the development of tocotrienol-fortified foods.

Supercritical CO2 Extraction of Rice Bran Oil -the Technology, Manufacture, and Applications

Rice bran is a good source of nutrients that have large amounts of phytochemicals and antioxidants. Conventional rice bran oil production requires many processes that may deteriorate and degrade these valuable substances. Supercritical CO₂ extraction is a green alternative method for producing rice bran oil. This work reviews production of rice bran oil by supercritical carbon dioxide (SC-CO₂) extraction. In addition, the usefulness and advantages of SC-CO₂ extracted rice bran oil for edible oil and health purpose is also described.

Simultaneous quantification of vitamin E, γ-oryzanols and xanthophylls from rice bran essences extracted by supercritical CO2

Since the nutrition value of rice is diminished during rice processing, technology that can preserve and sustain functional compounds is necessary. In this study, supercritical carbon dioxide (SC-CO2) extraction was optimized for operational conditions (time, temperature, pressure and modifier) to extract vitamin E, γ-oryzanols and xanthophylls from rice bran. The simultaneous quantification of the compounds was developed using high-performance liquid chromatography with diode array and fluorescence detectors. Central composite design and respond surface methodology were applied to achieve optimum extraction conditions. The optimized conditions were 60min, 43°C, 5420psi with 10% ethanol as a modifier. Pigmented rice bran extracts contained greater amounts of functional phytochemicals than non-pigmented rice bran extracts (0.68, 1410, and non-detectable μg/g compared with 16.65, 2480, and 0.10μg/g of vitamin E, γ-oryzanols and xanthophylls in pigmented and non-pigmented ones, respectively). SC-CO2 extraction with modifier would be promising for preparation of phytochemical essences for therapeutic purpose.

Phosphatidylcholine hydroperoxide promotes VEGF-induced angiogenesis in endothelial cells and rat aorta ring cultures

BACKGROUND

Phosphatidylcholine hydroperoxide (PCOOH) is a primary oxidation product of PC, and is markedly accumulated in blood plasma and arterial walls in atherosclerotic animals and humans. The role of PCOOH in the induction of angiogenesis is unknown.

METHODS

In this study, we investigated whether PCOOH stimulated angiogenic responses (e.g., vascular endothelial growth factor (VEGF)-induced cell proliferation, migration, and tube formation, and angiogenesis-related gene/protein expression) in human umbilical vein endothelial cells (HUVEC) and in an ex vivo rat aorta model.

RESULTS

VEGF induced proliferation, migration, and tube formation of HUVEC, and these angiogenic responses were all enhanced by PCOOH but not by native (nonoxidized) PC. The angiogenic effects of PCOOH are considered to be mediated via generation of reactive oxygen species and activation of both PI3K/AKT and MAPK pathways. The angiogenic activities of PCOOH were also confirmed by the rat aortic ring assay.

CONCLUSIONS

These results indicate that PCOOH can elicit several angiogenic responses.

GENERAL SIGNIFICANCE

The present study implies an important role of PCOOH in atherosclerosis progression and plaque instability.

Amadori-glycated phosphatidylethanolamine, a potential marker for hyperglycemia, in streptozotocin-induced diabetic rats

It has been demonstrated in vivo that lipid glycation products such as Amadori-glycated phosphatidylethanolamine (Amadori-PE) accumulate in the plasma of diabetic humans and animals, but how lipid glycation products are formed under hyperglycemic conditions are not clear. We sought to clarify the occurrence of lipid glycation and its relationships with lipid peroxidation and protein glycation during the development of hyperglycemia using the streptozotocin (STZ)-induced diabetic rat model. A significant increase in Amadori-PE was observed in STZ rats 7 days after STZ treatment, and Amadori-PE (especially 18:0-20:4 Amadori-PE) was found at high levels in the blood and in organs that are strongly affected by diabetes, such as the kidney. Significant changes in Amadori-PE appeared to occur prior to changes in levels of oxidized lipids, which increased after 21-28 days. In addition, accumulation of Nε-(carboxymethyl)lysine (CML), a protein glycation product, proceeded somewhat more slowly and moderately than that of Amadori-PE, suggesting that Amadori-PE and CML are early and advanced glycation products, respectively. Our results suggest that Amadori-PE may be a useful predictive marker for hyperglycemia, particularly in the early stages of diabetes. Similar speculations have been made from previous human studies, but this study provides a direct evidence to support the speculations in rat study.

Tocotrienol distribution in foods: estimation of daily tocotrienol intake of Japanese population

Tocotrienol (T3) is an unsaturated form of natural vitamin E that has been focused on because of its potential health benefits (i.e., antioxidative, antihypercholesterolemic, and antiangiogenic effects). The presence of T3 in some plant sources (e.g., rice bran and palm oil) is known, but its distribution in other edible sources and its daily intake remain unclear. In this study, we aimed at clarifying the distribution of T3 in various food sources and estimating the daily T3 intake of Japanese population. T3 contents of 242 food items and 64 meal items were measured by using normal-phase HPLC with fluorescence detection. As for the results, T3 contents were nondetectable to 12 mg T3/kg wet wt of food items, and nondetectable to 1.3 mg T3/item of processed (cooked) meal. Accordingly, the daily intake of T3 was estimated as 1.9-2.1 mg T3/day/person. The estimated daily intake of T3 appears rather low compared with the intake of tocopherol (8-10 mg/day/person as reported in the Japanese National Nutrition Survey), and additional T3 is important for its therapeutic aspects.

delta-Tocotrienol suppresses VEGF induced angiogenesis whereas alpha-tocopherol does not

Recently, tocotrienol (T3), a less well-known form of vitamin E, has gained considerable attention as a potent antiangiogenic agent. However, the majority of vitamin E research has focused on tocopherol (Toc), with some studies indicating alpha-Toc may prevent tumor angiogenesis. In this study, we aimed to clarify the differences in antiangiogenic potential between delta-T3 and alpha-Toc. We showed delta-T3 (2.5-5 microM) completely abolished proliferation, migration and tube formation of human umbilical vein endothelial cells (HUVECs), whereas a similar dose of alpha-Toc had no such effects. delta-T3 suppressed VEGF receptor 2 (VEGFR-2) signaling, and activated caspases in HUVECs. In addition, via an in vivo mouse Matrigel plug angiogenesis assay, we found that delta-T3 (30 microg), but not alpha-Toc, inhibited tumor cell-induced vessel formation. In summary, our results demonstrate delta-T3 has superior antiangiogenic activities to alpha-Toc, and provide insights into the different mechanisms responsible for this effect of T3 and Toc.

Cross-fertilization for enhancing tocotrienol biosynthesis in rice plants and QTL analysis of their F2 progenies

As rice bran tocotrienol (T3) has been known to have a wide range of physiological functions (e.g., antiangiogenesis), we aimed at developing a T3-rich rice variety for nutraceutical purposes. T3 content in more than 250 kinds of rice bran samples were investigated, and Milyang23 was found as the best variety rich in T3. The variety was therefore chosen for cross-fertilization with Koshihikari. Among obtained F(2) progenies, some of them became improved in T3 content (up to 2-fold of reference Koshihikari). QTL analysis of the F(2) progenies revealed five putative loci corresponding to T3 biosynthesis, in which the main loci were located near a marker RM3827 on chromosome 6. The results show that cross-breeding is effective in improving rice bran T3 and provides more genetic understanding on T3 biosynthesis in rice plants.

Quantitation of tocotrienol and tocopherol in various rice brans

Rice bran is abundant in bioactive compounds including tocotrienol (T3, unsaturated vitamin E). T3 has been reported about its potential functionalities (i.e., antiangiogenic effect), so much attention has been paid on usability of rice bran T3. Hence, we developed a rapid screening method for T3-rich rice bran by one-step equilibrium direct solvent extraction followed by normal phase high-performance liquid chromatography (HPLC). The method gave high-extraction rate of rice bran T3 and tocopherol (above 90%), and the determination of vitamin E by HPLC was completed within 15 min. Using the method, an average of total T3 content in 109 kinds of rice bran samples was 830 mug/g dry wt. Kouchi-Akamai, Joushuu, and Wataribune were found as the T3-rich rice bran varieties (1350-1430 microg T3/g dry wt). According to T3 ratio against total vitamin E (wt %), the average ratio was 61%. Hirayama, Moritawase, and Kaneko were found as the varieties having the highest T3 ratio (80-86%). Since T3 content in Koshihikari rice bran (the leading variety in Japan) was a little above the average, we cross-fertilized Koshihikari with T3-rich varieties and found that T3 content or ratio in F1 was improved compared with Koshihikari. The varieties found rich in T3 could be used for nutraceutical purpose.