Skip to main content
NCBI home page
Food Science and Biotechnology logoLink to Food Science and Biotechnology
. 2025 Aug 19;35(3):485–492. doi: 10.1007/s10068-025-01973-1

Glutathione analysis and quantification in Korean supplements: method development and validation

Sieun Ham 1,#, Hyeonju Bae 1,#, Joong-Hyuck Auh 2, Sangdoo Ahn 3, Hyang Sook Chun 2, Byung Hee Kim 1,✉
PMCID: PMC12894451  PMID: 41695800

Abstract

In this study, a liquid chromatography–ultraviolet (LC–UV) detection method was established for the rapid and accurate analysis of reduced and oxidized glutathione in glutathione supplements without the need for derivatization. Method validation revealed a satisfactory linearity (R2 ≥ 0.999), accuracy (recovery: 92.18–102.85%), and precision (relative standard deviation ≤ 1.91%), with the limits of detection (for 100 g of product) being 0.26 and 0.15 g for reduced glutathione and oxidized glutathione, respectively. The developed method was applied to 60 glutathione supplements (25 films, 24 tablets, 6 granules, and 5 powders) distributed in Korea between May and September 2024. Significant variations in the glutathione content were observed across products and formulations, with discrepancies between the measured and labeled values in certain samples. The presented method holds great potential for quality control and label accuracy verification in glutathione supplements.

Keywords: Glutathione supplement, LC–UV, Method validation, Oxidized glutathione, Reduced glutathione

Introduction

Glutathione is a tripeptide composed of l-glutamic acid, l-cysteine, and l-glycine (Fiser et al., 2015), held together by peptide bonds between the carboxyl group of the glutamic acid side chain and the alpha-amino group of cysteine, and between the alpha-carboxyl group of cysteine and the alpha-amino group of glycine (Sürmeli and Duran, 2024). In food and the human body, glutathione exists in both its reduced and oxidized forms, which interconvert as part of cellular processes (Raya and Bandyopadhyay, 2018; Zieliñski and Rzedzicki, 2001). Reduced glutathione undergoes oxidation into the oxidized glutathione form, which is restored to its reduced state by receiving an electron from NADPH via glutathione reductase (Georgiou-Siafis and Tsiftsoglou, 2023). Reduced glutathione is abbreviated as GSH, due to the presence of a thiol group (–SH) on its cysteine residue, while oxidized glutathione is abbreviated as GSSG, because it is formed through disulfide bonding (–S–S–) between two GSH molecules (Fig. 1). Glutathione acts as an antioxidant in its reduced form, protecting cells by reducing peroxides and free radicals (Birben et al., 2012). Glutathione also plays a crucial role in various biological processes, including detoxification, immune support, and skin whitening (Arjinpathana and Asawanonda, 2012; Perricone et al., 2009).

Fig. 1.

Fig. 1

Open in a new tab

Chemical structures of reduced glutathione (GSH) and oxidized glutathione (GSSG)

In 2020, the global glutathione market was valued at approximately USD 34.10 million. With an estimated average annual growth rate of 5.1%, the market is projected to reach USD 50.76 million by 2029 (Data Bridge Market Research, 2021). The United States (U.S.) Food and Drug Administration has classified glutathione as “Generally Recognized as Safe”, confirming its safety (Karunarathna et al., 2024). Glutathione is widely marketed as a dietary supplement in the U.S., owing to its antioxidant, detoxifying, and skin whitening properties (Schleiff et al., 2024). Conversely, while glutathione is also used as a dietary supplement in Korea, regulations restrict the advertisement and labeling of its functional benefits.

Glutathione supplements are typically produced from Saccharomyces cerevisiae extracts (Li et al., 2004). In Korea, such supplements are mainly available in the form of films, tablets, granules, or powders. Among these, films are made using orodispersible formulations, which are thin, flexible, macromolecular structures that rapidly dissolve or disintegrate in the mouth without water. This allows for the fast release of the active ingredients (Jacob et al., 2023; Musazzi et al., 2020) and direct absorption through the oral mucosa rather than passing through the digestive system, leading to a higher absorption rate compared to tablets, granules, powders, liquids, capsules, or syrups (Salawi, 2022).

Previous studies have primarily used liquid chromatography (LC) for the analysis of glutathione in food. Various detection methods have been employed, including ultra-violet (UV; Schofield and Chen, 1995), fluorescence (Demirkol et al., 2004; Marchand and de Revel, 2010; Tsiasioti et al., 2021; Zacharis et al., 2011), and tandem mass spectrometry detection (Du Toit et al., 2007; Shakoor et al., 2025). These techniques have been used to analyze both the reduced and oxidized forms of glutathione (Du Toit et al., 2007; Marchand and de Revel, 2010; Schofield and Chen, 1995; Tsiasioti et al., 2021) or only reduced glutathione (Demirkol et al., 2004; Shakoor et al., 2025; Zacharis et al., 2011) in various food matrices, including wheat flour (Schofield and Chen, 1995), meat (Shakoor et al., 2025), fruits (Demirkol et al., 2004), vegetables (Demirkol et al., 2004; Tsiasioti et al., 2021; Zacharis et al., 2011), and wine (Du Toit et al., 2007; Marchand and de Revel, 2010; Tsiasioti et al., 2021). Some studies incorporated a derivatization step during pretreatment (Demirkol et al., 2004; Marchand and de Revel, 2010; Schofield and Chen, 1995; Tsiasioti et al., 2021; Zacharis et al., 2011), while others did not (Du Toit et al., 2007; Shakoor et al., 2025). However, to the best of our knowledge, no study has yet reported the simultaneous analysis of reduced and oxidized glutathione in food while achieving a shorter analysis time and avoiding derivatization through simple pretreatment, using the relatively cost-effective LC–UV.

Glutathione supplements have attracted consumers’ attention recently, leading to an increased demand for accurate information regarding the glutathione concentrations in such products. A recent study examined the glutathione content of supplements available on the Korean market (Consumer Action for Future, 2024) using LC–UV methods based on pharmacopoeia testing protocols. However, only reduced glutathione was analyzed. Current pharmacopoeia methods are designed primarily for high purity drugs (Ministry of Food and Drug Safety, 2023) and are less suitable for analyzing glutathione supplements, particularly those derived from yeast extracts, because they contain various other compounds, including carbohydrates, lipids, and salts (Korea Consumer Agency, 2024).

In this study, a rapid LC–UV method was developed for the effective isolation and accurate quantification of reduced and oxidized glutathione in glutathione supplements, without requiring derivatization. Furthermore, the method was applied on commercially available Korean products to evaluate their glutathione content.

Materials and methods

Materials

Reduced (≥ 98%) and oxidized (≥ 98%) glutathione reference standards and HPLC-grade trifluoroacetic acid (≥ 99%) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Sodium perchlorate monohydrate (≥ 98%) was obtained from Samchun Chemicals (Seoul, Korea). HPLC-grade pure water and acetonitrile (≥ 99.9%) were purchased from J.T. Baker (Phillipsburg, NJ, USA).

Glutathione supplements

The glutathione supplements used in this study were purchased from online retailers in Korea between May and September 2024. A total of 60 supplements were obtained, comprising 25 films, 24 tablets, 6 granules, and 5 powders. All products were stored according to the manufacturer’s recommendations (e.g., room temperature) and analyzed before their use-by date. Once opened, the samples were analyzed immediately and any remaining portions were discarded.

Glutathione content analysis

The glutathione content in the supplements was analyzed using the LC–UV method described by Lipsa et al. (2015) with slight modifications. Each sample (100 mg) was mixed with 25 mL of distilled water for 1 min using a vortex and the volume was then adjusted to 30 mL with distilled water. After centrifugation at 2250 × g for 10 min (Rotor Speed Table VS-5000i, Vision Scientific, Daejeon, Korea), 200 µL of the supernatant was collected and combined with 800 µL of the mobile phase, followed by thorough mixing using a vortex. After filtration using a 0.45-µm UHP syringe filter (Woongki, Seoul, Korea), the resulting solution was analyzed using an HPLC system (Waters e2695, Waters, Milford, MA, USA) equipped with a Capcell Pak C18 MG II S5 column (250 mm × 4.6 mm i.d., 5 µm film thickness, Osaka Soda, Amagasaki, Japan) and a UV detector. The mobile phase consisted of 0.05% trifluoroacetic acid in a water/acetonitrile mixture (95:5, v/v) containing 0.1 M sodium perchlorate. The flow rate was 1.0 mL/min and both the column and detector were maintained at 30 °C. The analysis was performed at a wavelength of 220 nm with a total run time of 20 min and an injection volume of 10 µL. Each sample was analyzed in triplicate and standard calibration curves were constructed using reference standards of reduced and oxidized glutathione (5, 10, 25, 50, 100, 250, 500, and 1000 µg/mL). The reduced and oxidized glutathione contents were determined from the calibration curves, and the total glutathione content was calculated as their sum. The results are expressed in g/100 g of sample.

Validation of the analytical method

The LC–UV method for quantifying reduced and oxidized glutathione in glutathione supplements was validated for its specificity, linearity, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ). Specificity was confirmed by comparing chromatograms of reference standards and test solutions to evaluate potential interferences and retention time consistency (AOAC, 2023). Linearity was assessed using the coefficient of determination (R2) of standard calibration curves for reduced and oxidized glutathione. Accuracy was evaluated by spiking a baseline sample (a film-type glutathione supplement) with three different concentrations of reference standards (5, 10, and 15 g/100 g for reduced glutathione; 0.25, 0.5, and 0.75 g/100 g for oxidized glutathione), followed by recovery calculations. Precision was evaluated based on repeatability and reproducibility. Repeatability was determined by performing the aforementioned recovery experiments in triplicate and calculating the relative standard deviation (RSD) of the measured values. Reproducibility was determined by calculating the RSD of the measured values from a baseline sample spiked at the middle concentration (i.e., 10 g/100 g reduced glutathione, 0.5 g/100 g oxidized glutathione) analyzed in triplicate on different dates by two independent analysts (AOAC, 2023). LOD and LOQ were calculated using the standard deviation (σ) of the response and the slope (S) of the standard calibration curve. The σ value was derived from the standard deviation (SD) of the residuals of the calibration curve generated from three replicate trials, and the LOD and LOQ were determined using the equations 3.3 × σ/S and 10 × σ/S, respectively (Kennedy et al., 1995).

Quality control of analysis

The quality control of the glutathione analysis was performed using an in-house quality control (IHQC) sample and a quality control chart, following the AOAC guidelines (2023). A single powder-type glutathione supplement sample was designated as the IHQC. The IHQC sample was analyzed in eight replicate trials to determine the mean and SD of the total glutathione content. The upper and lower control limits were set as the mean ± 2SD, while the upper and lower action limits were established at mean ± 3SD. For each analytical batch, IHQC was analyzed to ensure that its measured value fell within the control limits.

Statistical analysis

Statistical analysis was conducted using IBM SPSS Statistics (version 28.0) software (IBM Corporation, Chicago, IL, USA). All data are presented as the mean of triplicate measurements. The differences between the measured and labeled values for each formulation were analyzed after assessing normality using the Shapiro–Wilk test. If normality was confirmed (p > 0.05), a paired t-test was performed; otherwise, the Wilcoxon signed-rank test was used. The significant level for both tests was set at p < 0.05.

Results and discussion

Validation of the analytical method

The LC–UV method employed in this study for glutathione analysis in supplements was developed by Lipsa et al. (2015) for quantifying glutathione in human pulmonary cells. Jeon et al. (2023) successfully applied it to measure glutathione concentrations in S. cerevisiae cells. However, its application to food matrices, including glutathione supplements, has not been previously reported. Therefore, before applying this method to glutathione supplements, its validation for this specific matrix was required.

The validity of the analytical method established in this study was verified; Fig. 2 shows the chromatograms of the reduced and oxidized glutathione reference standards, as well as the glutathione supplements (all formulations). In both the reference standards and samples, reduced glutathione was detected at 4.1–4.3 min and oxidized glutathione appeared at 6.4–6.6 min, indicating that both peaks were clearly separated in all formulations, without interfering with other peaks. Table 1 summarizes the linearity, accuracy, precision, LOD, and LOQ results. The standard calibration curves for both reduced and oxidized glutathione demonstrated good linearity, with R2 values ≥ 0.999 across the 5–1000 µg/mL concentration range. The accuracy and precision of the analytical method were validated by adding known concentrations of a reference standard to a film-type glutathione supplement. The concentrations added were determined based on the range of the reduced and oxidized glutathione concentrations measured in the analyzed samples. The recovery, an indicator of accuracy, was 97.22% at a reduced glutathione concentration of 5 g/100 g, falling within the AOAC (2023) acceptable range of 92–105%. At concentrations of 10 g/100 g and 15 g/100 g, the recoveries were 100.95% and 100.43%, respectively, meeting the AOAC (2023) criteria of 95–102%, thereby demonstrating satisfactory accuracy. Similarly, for oxidized glutathione, the recoveries at concentrations of 0.25, 0.5, and 0.75 g/100 g were 92.18%, 92.76%, and 102.85%, respectively, all being within the AOAC (2023) acceptable range of 90–108% and confirming a reliable recovery. RSD, a measure of repeatability, was 0.86% at a reduced glutathione concentration of 5 g/100 g, falling within the acceptable range (≤ 2%) according to AOAC (2023). Furthermore, at concentrations of 10 and 15 g/100 g, RSD was within the AOAC (2023) acceptable range (≤ 1.5%), being 1.47% and 1.05%, respectively, indicating good repeatability. For oxidized glutathione, RSD was also within the AOAC (2023) acceptable range (≤ 3%) at 1.26%, 0.99%, and 1.36% for concentrations of 0.25, 0.5, and 0.75 g/100 g, respectively, further demonstrating the good repeatability of the method. As a measure of reproducibility, RSD was 1.31% at a reduced glutathione concentration of 10 g/100 g, which is within the acceptable range (≤ 3%) per AOAC (2023), and 1.91% at a concentration of 0.5 g/100 g, also within the acceptable limit (≤ 6%), confirming the good reproducibility of the method. Based on the test solution, the LOD and LOQ values were 27.9 and 93.1 μM, respectively, for reduced glutathione and 8.2 and 27.2 μM, respectively, for oxidized glutathione. When converted to g/100 g of glutathione supplement, the LOD and LOQ values for reduced glutathione were 0.26 and 0.86 g, respectively, whereas for oxidized glutathione, they were 0.15 and 0.50 g, respectively.

Fig. 2.

Fig. 2

Open in a new tab

Liquid chromatography–ultraviolet chromatograms of reduced glutathione (GSH) and oxidized glutathione (GSSG). (A) Mixed reference standards (GSH 250 µg/mL, GSSG 250 µg/mL), (B) commercial film-type glutathione supplement, (C) commercial tablet-type glutathione supplement, (D) commercial granule-type glutathione supplement, and (E) commercial powder-type glutathione supplement. Peak 1 GSH; Peak 2 GSSG

Table 1.

Linearity, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ) of the developed liquid chromatography–ultraviolet detection method for quantitative analysis of reduced glutathione (GSH) and oxidized glutathione (GSSG)

Analyte Spiking level (g/100 g) Accuracy (recovery, %) Repeatability (RSD, %) Reproducibility (RSD, %) LOD (g/100 g) LOQ (g/100 g) Calibration curve equation (coefficient of determination, R2)
GSH 5 97.22 0.86 1.31 0.26 0.86 y = 352.16x − 974.58 (R2 = 0.9999)
10 100.95 1.47
15 100.43 1.05
GSSG 0.25 92.18 1.26 1.91 0.15 0.50 y = 537.07x − 327.2 (R2 = 1.0000)
0.5 92.76 0.99
0.75 102.85 1.36
Open in a new tab

RSD relative standard deviation

The sensitivity of the developed LC–UV method was comparable to the method used by Schofield and Chen (1995), who employed the same LC–UV technique to analyze reduced and oxidized glutathione in wheat flour, with LOD values of 20 μM for reduced glutathione and 10 μM for oxidized glutathione (based on the test solution). However, previous LC methods for glutathione analysis in food matrices, including those utilizing fluorescent detection (Marchand and de Revel, 2010; Tsiasioti et al., 2021; Zacharis et al., 2011) or tandem mass spectrometry detection (Du Toit et al., 2007), exhibited LOD values of 0.1 and 1.3 μM, respectively, for reduced glutathione. Consequently, the sensitivity of our LC–UV method was lower than that of methods employing alternative detection technologies. Nevertheless, our analytical method demonstrated reliability for quantifying glutathione in supplements. Specifically, our method provided quantitatively accurate results for supplements containing a minimum of 0.86 g/100 g of reduced glutathione or 0.50 g/100 g of oxidized glutathione.

Quality control and consistency in glutathione analysis

In this study, the total glutathione content in 60 glutathione supplements available on the Korean market was analyzed over a period of eight months. To ensure the reliability of the analysis results throughout the study period, an IHQC sample was regularly analyzed alongside the glutathione supplement samples, and a quality control chart for the total glutathione analysis was created (Fig. 3). The glutathione measurements for the IHQC sample consistently fell within the upper and lower control limits. This confirms that potential environmental factors influencing the analysis results, such as analyst variability or the condition of the analytical equipment employed, were effectively controlled throughout the study period.

Fig. 3.

Fig. 3

Open in a new tab

In-house quality control chart of the powder-type glutathione supplement

Glutathione content and variability in supplements

The cells of living organisms generally maintain a higher concentration of reduced glutathione compared to oxidized glutathione (Hwang et al., 1992). This is attributed to the action of glutathione reductase, which reduces oxidized glutathione to its reduced form using NADPH as an electron donor (Georgiou-Siafis and Tsiftsoglou, 2023). In the cells of S. cerevisiae, a common source of extracts used in glutathione supplements, the ratio of reduced to oxidized glutathione is typically maintained in the range of 10–50:1 (Jeon et al., 2023; Raghavendran et al., 2020). However, this ratio can be altered by environmental factors, such as oxidative stress (Zechmann et al., 2011).

Table 2 shows the reduced, oxidized, and total glutathione contents measured in supplements available in the Korean market, using the method established in this study. Although some oxidized glutathione content values were below the LOQ of 0.50 g/100 g of product, they were consistently detected across replicates and therefore included in the analysis to allow for reliable comparisons among samples. A substantial variability in the glutathione contents was observed across the tested products, with mean values of 6.05, 0.31, and 6.34 g/100 g for the reduced, oxidized, and total glutathione contents, respectively. Significant differences were also noted between the formulation types. Film-type products (9.44 g/100 g) had the highest mean total glutathione content, followed by powders (7.49 g/100 g), tablets (3.63 g/100 g), and granules (3.32 g/100 g). This ranking is consistent with the labeled glutathione contents. Although the ratios of reduced to oxidized glutathione varied across the tested products, the mean ratio was 25:1, which is similar to the ratio observed in S. cerevisiae cells in previous studies (Jeon et al., 2023; Raghavendran et al., 2020). However, some products contained no detectable amounts of either reduced or oxidized glutathione. Specifically, the reduced glutathione content was below the LOD value in 6 products (5 tablets and 1 granule), while 25 products (3 films, 14 tablets, 4 granules, and 4 powders) exhibited oxidized glutathione contents below the LOD.

Table 2.

Glutathione content (g/100 g) in commercial glutathione supplements

Type n GSH GSSG Total glutathionesa
Mean (range, g/100 g) Mean (range, g/100 g) Mean (range, g/100 g)
Film 25 8.92 (1.62–19.90) 0.51 (ND–1.52) 9.44 (1.62–20.28)
Tablet 24 3.51 (ND–19.82) 0.15 (ND–0.83) 3.63 (ND–20.65)
Granule 6 3.12 (ND–8.59) 0.23 (ND–0.83) 3.32 (ND–8.92)
Powder 5 7.34 (0.57–13.94) 0.17 (ND–0.42) 7.49 (0.59–14.36)
Total 60 6.05 (ND–19.90) 0.31 (ND–1.52) 6.34 (ND–20.65)
Open in a new tab

GSH reduced glutathione, GSSG oxidized glutathione, ND not detected [i.e., < limit of detection (LOD); per sample 100 g, LOD = 0.26 g for GSH and 0.15 g for GSSG]

aCalculated as the sum of GSH and GSSG content

Comparison of measured and labeled glutathione content in supplements

The measured and labeled total glutathione contents were compared across the different formulations of glutathione supplements, as shown in Fig. 4. Given the relatively small sample sizes per formulation (5–25 samples per formulation) (Das and Imon, 2016), the Shapiro–Wilk test was first used to assess the normality of the differences between the measured and labeled values. The differences followed a normal distribution for films and granules, for which paired t-tests were performed. However, tablets and powders did not meet the normality assumption and the Wilcoxon signed-rank test was applied instead. No significant difference was found between the measured and labeled glutathione contents in granules (measured: 3.32 g/100 g, labeled: 3.09 g/100 g) and powders (measured: 7.49 g/100 g, labeled: 11.77 g/100 g). Conversely, the measured glutathione contents in films (9.44 g/100 g) and tablets (3.63 g/100 g) were significantly lower than the labeled values (21.95 g/100 g and 7.76 g/100 g, respectively). These findings suggest that the magnitude of the discrepancy between the measured and labeled glutathione content varied across formulation types, though the causes of these discrepancies remain unclear.

Fig. 4.

Fig. 4

Open in a new tab

Total glutathione contents in the measured and labeled values. The asterisk (*) denotes significant differences between the measured and labeled values (p < 0.05). NS not significant (p > 0.05). The sample sizes were 25 for film-type, 24 for tablet-type, 6 for granule type, and 5 for powder-type products

Glutathione is known to be stable for up to 39 months when stored in a sealed container at room temperature and normal relative humidity (Alanazi et al., 2015). The products analyzed in this study were all stored under similar conditions, with their use-by dates ranging from 1 to 3 years. Chen and Schofield (1996) reported that wheat flour stored in unsealed paper sacks at 20 °C for 40 days showed approximately 60% and 30% reductions in its reduced and oxidized glutathione contents, respectively, during the first 10 days, after which the levels remained stable. These findings suggest that the stability of glutathione may be influenced by the packaging types and storage conditions of the products, which could be related to the discrepancies in the glutathione levels observed in certain formulations. However, it should be noted that this study only measured the glutathione content in the final products, and the effects of packaging types or storage conditions during the manufacturing and distribution stages on glutathione stability were not directly evaluated.

In conclusion, in this study we successfully established a rapid LC–UV method that effectively isolates and accurately quantifies both reduced and oxidized glutathione in glutathione supplements without the need for a derivatization process. Our analytical method demonstrated satisfactory performance in terms of linearity, accuracy, precision, LOD, and LOQ, offering an essential analytical tool for quality control and verification of label accuracy in glutathione supplements. The developed method was applied to various formulations (films, tablets, granules, powders) of glutathione supplements available on the Korean market, to assess their glutathione content, revealing differences in glutathione content across products and formulations, as well as discrepancies between the measured and labeled values for certain products. To elucidate the causes of these discrepancies, further investigations should be conducted not only on the final products but also on the ingredients and intermediate products during the manufacturing and distribution stages. Such monitoring would provide consumers with more accurate information regarding the glutathione contents of supplements available on the Korean market.

Acknowledgements

This study was supported by a Grant (22193MFDS471) from the Ministry of Food and Drug Safety in 2024.

Declarations

Conflict of interest

The authors have no conflict of interest to disclose.

Footnotes

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Sieun Ham and Hyeonju Bae contributed equally to this research.

References

  1. Alanazi AM, Mostafa GA, Al-Badr AA. Glutathione. Vol. 40, pp. 43-158. In: Profiles of Drug Substances, Excipients and Related Methodology. Brittain HG (ed). Academic, San Diego, CA, USA (2015) [DOI] [PubMed] [Google Scholar]
  2. AOAC. Official Methods of Analysis of AOAC International. 22nd ed. Association of Official Agricultural Chemists International, New York, USA, pp. AK-1-AK-32 (2023) [Google Scholar]
  3. Arjinpathana N, Asawanonda P. Glutathione as an oral whitening agent: a randomized, double-blind, placebo-controlled study. Journal of Dermatological Treatment 23: 97-102 (2012) [DOI] [PubMed] [Google Scholar]
  4. Birben E, Sahiner UM, Sackesen C, Erzurum S, Kalayci O. Oxidative stress and antioxidant defense. World Allergy Organization Journal 5: 9-19 (2012) [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Chen X, Schofield JD. Changes in the glutathione content and breadmaking performance of white wheat flour during short-term storage. Cereal Chemistry 73: 1-4 (1996) [Google Scholar]
  6. Consumer Action for Future. Glutathione, You Need to Buy It Considering the Purity Content. Available from: https://www.consumer.go.kr/consumer/index.do. Assessed Jan. 21, 2025.
  7. Das KR, Imon AHMR. A brief review of tests for normality. American Journal of Theoretical and Applied Statistics 5: 5-12 (2016) [Google Scholar]
  8. Data Bridge Market Research. Global Glutathione Market—Industry Trends and Forecast to 2029. Available from: https://www.databridgemarketresearch.com/. Assessed Jan. 21, 2025
  9. Demirkol O, Adams C, Ercal N. Biologically important thiols in various vegetables and fruits. Journal of Agricultural and Food Chemistry 52: 8151-8154 (2004) [DOI] [PubMed] [Google Scholar]
  10. Du Toit WJ, Lisjak K, Stander M, Prevoo D. Using LC–MS/MS to assess glutathione levels in South African white grape juices and wines made with different levels of oxygen. Journal of Agricultural and Food Chemistry 55: 2765-2769 (2007) [DOI] [PubMed] [Google Scholar]
  11. Fiser B, Jójárt B, Szőri M, Lendvay G, Csizmadia IG, Viskolcz B. Glutathione as a prebiotic answer to α-peptide based life. The Journal of Physical Chemistry B 119: 3940-3947 (2015) [DOI] [PubMed] [Google Scholar]
  12. Georgiou-Siafis SK, Tsiftsoglou AS. The key role of GSH in keeping the redox balance in mammalian cells: mechanisms and significance of GSH in detoxification via formation of conjugates. Antioxidants 12: 1953 (2023) [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Hwang C, Sinskey AJ, Lodish HF. Oxidized redox state of glutathione in the endoplasmic reticulum. Science 257: 1496-1502 (1992) [DOI] [PubMed] [Google Scholar]
  14. Jacob S, Boddu SHS, Bhandare R, Ahmad SS, Nair AB. Orodispersible films: current innovations and emerging trends. Pharmaceutics 15: 2753 (2023) [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Jeon GB, Lee HJ, Park JP, Park K, Choi CH, Kim SK. Efficient production of glutathione in Saccharomyces cerevisiae via a synthetic isozyme system. Biotechnology Journal 18: 2200398 (2023) [DOI] [PubMed] [Google Scholar]
  16. Karunarathna I, Bandara S, Jayawardana A, de Alvis K, Gunasena P, Hapuarachchi T, Ekanayake U, Rajapaksha S, Gunawardana K, Aluthge P, Gunathilake S. Glutathione for skin lightening: a review of efficacy, safety, and clinical evidence. Available from: https://www.researchgate.net/publication/382869615. Accessed Jan. 21, 2025
  17. Kennedy ER, Fischbach TJ, Song R, Eller PM, Shulman SA. Guidelines for Air Sampling and Analytical Method Development and Evaluation. U.S. Department of Health and Human Services. Cincinnati, OH, USA. pp. 65-68 (1995) [Google Scholar]
  18. Korea Consumer Agency. Some Glutathione Foods Require Improved Labeling and Advertising of Glutathione Content. Available from: https://www.kca.go.kr/home/main.do. Accessed Jan. 21, 2025
  19. Li Y, Wei G, Chen J. Glutathione: a review on biotechnological production. Applied Microbiology and Biotechnology 66: 233-242 (2004) [DOI] [PubMed] [Google Scholar]
  20. Lipsa D, Cacho C, Leva P, Barrero-Moreno J, Aguar P. Development of a HPLC–UV method for the simultaneous determination of intracellular glutathione species in human cells. Journal of Analytical and Bioanalytical Techniques 6: 259 (2015) [Google Scholar]
  21. Marchand S, de Revel G. A HPLC fluorescence-based method for glutathione derivatives quantification in must and wine. Analytica Chimica Acta 660: 158-163 (2010) [DOI] [PubMed] [Google Scholar]
  22. Ministry of Food and Drug Safety. Korean Pharmaceutical. Available from: https://www.mfds.go.kr/index.do. Assessed Jan. 21, 2025
  23. Musazzi UM, Khalid GM, Selmin F, Minghetti P, Cilurzo F. Trends in the production methods of orodispersible films. International Journal of Pharmaceutics 576: 118963 (2020) [DOI] [PubMed] [Google Scholar]
  24. Perricone C, De Carolis C, Perricone R. Glutathione: a key player in autoimmunity. Autoimmunity Reviews 8: 697-701 (2009) [DOI] [PubMed] [Google Scholar]
  25. Raghavendran V, Marx C, Olsson L, Bettiga M. The protective role of intracellular glutathione in Saccharomyces cerevisiae during lignocellulosic ethanol production. AMB Express 10: 219 (2020) [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Raya CE, Bandyopadhyay D. Glutathione: a small molecule with big sense. International Journal of Pharma Sciences and Scientific Research 4: 39-44 (2018) [Google Scholar]
  27. Salawi A. An insight into preparatory methods and characterization of orodispersible film—a review. Pharmaceuticals 15: 844 (2022) [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Schleiff M, Chen J, Yang J, Sommers C, Shen X, Rodriguez J, Keire D, Shu Q. An isocratic HPLC–UV analytical procedure for assessment of glutathione and its related substances. Journal of Pharmaceutical and Biomedical Analysis 249: 116374 (2024) [DOI] [PubMed] [Google Scholar]
  29. Schofield JD, Chen X. Analysis of free reduced and free oxidised glutathione in wheat flour. Journal of Cereal Science 21: 127-136 (1995) [Google Scholar]
  30. Shakoor A, Al-Dalali S, Xie J, Zhang C, Hossen I. Insight into the effect of GSH curing treatment on the flavor formation of chicken meat. Food Chemistry 468: 142488 (2025) [DOI] [PubMed] [Google Scholar]
  31. Sürmeli T, Duran HE. Examination of glutathione S-transferase (GST) enzyme levels and some biochemical parameters in coronary artery patients. Journal of Research in Applied and Basic Medical Sciences 10: 191-204 (2024) [Google Scholar]
  32. Tsiasioti A, Zotou AS, Tzanavaras PD. Single run analysis of glutathione and its disulfide in food samples by liquid chromatography coupled to online post-column derivatization. Food Chemistry. 361: 130173 (2021) [DOI] [PubMed] [Google Scholar]
  33. Zacharis CK, Tzanavaras PD, Zotou A. Ethyl propiolate as a post-column derivatization reagent for thiols: development of a green liquid chromatographic method for the determination of glutathione in vegetables. Analytica Chimica Acta 690: 122-128 (2011) [DOI] [PubMed] [Google Scholar]
  34. Zechmann B, Liou LC, Koffler BE, Horvat L, Tomašić A, Fulgosi H, Zhang Z. Subcellular distribution of glutathione and its dynamic changes under oxidative stress in the yeast Saccharomyces cerevisiae. FEMS Yeast Research 11: 631-642 (2011) [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Zieliñski H, Rzedzicki Z. Reduced/oxidized glutathione index as a tool for food monitority oxidative stress during extrusion cooking. Journal of Food Processing and Preservation. 25: 197-206 (2001) [Google Scholar]

Articles from Food Science and Biotechnology are provided here courtesy of Springer

RESOURCES