Intervention of Acidophilus-casei dahi and Wheat bran against molecular alteration in colon carcinogenesis

An in vivo trial was conducted on seventy five rats allocated to three groups, first group was DMH control group, second group was Wheat bran-DMH group (WB-DMH) in which wheat bran was given along with DMH (1,2-dimethylhydrazine) injection, third group was Wheat bran-DMH-Ac Dahi group in which both wheat bran and Acidophilus-casei dahi (a probiotic microorganisms fermented dairy product) was given along with DMH injections. Animals received subcutaneous injections of DMH at a dose rate of 20 mg/kg body weight, once weekly for 15 weeks. The rats were dissected at 40th week of experiment and comet assay was done in colonic cells to assess the DNA damage. The c-myc and cox-2 expression was studied in rat tumour. A significant reduction in DNA damage (48.2%) was observed in WB-DMH-Ac Dahi group as compared to DMH control group (87.8%). The c-myc and cox-2 mRNA level was found highest in DMH control group as compared to WB-DMH and WB-DMH-Ac Dahi group. The results of present study show the enhanced protective potential of Acidophilus-casei and wheat bran against DMH induced molecular alteration in colonic cells during carcinogenesis.     

Assessment of DNA sensitivity in peripheral blood leukocytes after occupational exposure to microwave radiation: the alkaline comet assay and chromatid breakage assay

DNA sensitivity in peripheral blood leukocytes of radar-facility workers daily exposed to microwave radiation and an unexposed control subjects was investigated. The study was carried out on clinically healthy male workers employed on radar equipment and antenna system service within a microwave field of 10 μW/cm²–20 mW/cm² with frequency range of 1,250–1,350 MHz. The control group consisted of subjects of similar age. The evaluation of DNA damage and sensitivity was performed using alkaline comet assay and chromatid breakage assay (bleomycin-sensitivity assay). The levels of DNA damage in exposed subjects determined by alkaline comet assay were increased compared to control group and showed inter-individual variations. After short exposure of cultured lymphocytes to bleomycin cells of subjects occupationally exposed to microwave (MW) radiation responded with high numbers of chromatid breaks. Almost three times higher number of bleomycin-induced chromatid breaks in cultured peripheral blood lymphocytes were determined in comparison with control group. The difference in break per cell (b/c) values recorded between smokers and non-smokers was statistically significant in the exposed group. Regression analyses showed significant positive correlation between the results obtained with two different methods. Considering the correlation coefficients, the number of metaphase with breaks was a better predictor of the comet assay parameters compared to b/c ratio. The best correlation was found between tail moment and number of chromatid with breaks. Our results indicate that MW radiation represents a potential DNA-damaging hazard using the alkaline comet assay and chromatid breakage assay as sensitive biomarkers of individual cancer susceptibility.     

Probiotic characteristics of lactic acid bacteria isolated from kimchi

Aims: The present work was aimed at identifying strains of lactic acid bacteria (LAB) from kimchi, with properties suitable for use as starter cultures in yogurt fermentation. Methods and Results: A total of 2344 LAB strains were obtained from two different sources, one group consisted of commercial LAB strains from kimchi, and the second group consisted of those strains isolated from various types of kimchi. The LAB strains from both groups were screened for resistance to biological barriers (acid and bile salts), and the four most promising strains were selected. Further analysis revealed that KFRI342 of the four selected strains displayed the greatest ability to reduce the growth of the cancer cells, SNU‐C4. The in vivo efficacy of strains in quinone reductase induction assay was evaluated, and the extent of DNA strand breakage in individual cells was investigated using the comet assay. Strain KFRI342 was identified as Lactobacillus acidophilus by 16S rRNA sequence analysis, showed protection against tumour initiation and imparted immunostimulation as well as protection against DNA damage. Conclusions: Strain KFRI342, which showed probiotic characteristics reducing cancer cell growth, could be a suitable starter culture for yogurt fermentation because of its strong acid production and high acid tolerance. Significance and Impact of the Study: This is the first report to describe a bacterium, isolated from kimchi, Lact. acidophilus KFRI342 which has the probiotic characteristics and the acid tolerance needed for its use as a starter culture in yogurt fermentation.     

Insulin resistance is associated with DNA damage in peripheral blood cells in non-diabetic patients with genotype 1 chronic hepatitis C

Abstract

Background. In chronic liver diseases of different etiologies, including viral hepatitis, genotoxic effects of oxidative stress have been shown, both in clinical and in experimental conditions, suggesting that this mechanism may contribute to the evolution of the disease. Aim. To evaluate DNA damage in the peripheral blood of untreated non-diabetic patients with chronic hepatitis C and control subjects, and its correlation with demographic, anthropometric, biochemical, and histological parameters in the patient sample. Patients and methods. This study comprised 100 subjects of both genders, 60 of whom were treatment-naïve patients with positive serology for genotype 1 hepatitis C. The remaining 40 were blood donors with negative serology for hepatitis who were used as control subjects, and matched by gender, age, weight, and BMI. DNA damage was determined using the comet assay in the total peripheral blood. Results. The DNA damage evaluated by the comet assay revealed higher values in the group of patients with hepatitis compared with that in the control group. The relationships of the comet assay with the studied variables were assessed using multivariate analysis; significant correlations were only identified with insulin (r = 0.343, p = 0.008) and Homeostasis Model Assessment Insulin Resistance (HOMA-IR) (r = 0.331, p = 0.011). Conclusion. Patients with genotype 1 chronic hepatitis C have higher rates of DNA damage, as determined by comet assay and this alteration is correlated with the HOMA index of insulin resistance.     

Effect of probiotic fermented milk and chlorophyllin on gene expressions and genotoxicity during AFB₁-induced hepatocellular carcinoma

The aim of this study was to investigate the chemopreventive effect of probiotic fermented milk and chlorophyllin on aflatoxin B? (AFB?) induced hepatocellular carcinoma. In vivo trials were conducted on 200 Wistar rats allocated to eight groups. Rats in the positive control group were given intraperitoneal injection of aflatoxin B? at 450 μg/kg body weight twice a week for 6 weeks. The rats were sacrificed and dissected at 25th week of the experiment, and comet assay was carried out in hepatic cells to assess the genotoxicity or DNA damage. The tumour incidence was decreased by approximately one-third than AFB? control group. The expression of c-myc bax, bcl-2, cyclin D1, p53 and rasp-21 genes was also studied. A significant (P<0.05) reduction in DNA damage was observed in probiotic fermented milk with chlorophyllin group as compared to aflatoxin B? control group. The c-myc, bcl-2, cyclin D1 and rasp-21 level was found to be highest in AFB? control group as compared to the treatment group. The results advocate the enhanced protective potential of probiotic fermented milk and chlorophyllin against AFB?-induced molecular alterations in hepatic cells during carcinogenesis.     

Evidence that DNA damage is associated to phenylalanine blood levels in leukocytes from phenylketonuric patients

Phenylketonuria (PKU) is an inborn error of phenylalanine (Phe) metabolism, biochemically characterized by the accumulation of Phe and its metabolites in blood and tissues of affected patients. Treatment for PKU consists of a protein restricted diet supplemented with a mixture containing essential amino acids (other than Phe) and micronutrients. In recent years several authors have studied the pathomechanisms of the disease and demonstrated the existence of lipid and protein oxidative damage in PKU patients. In this work we investigated the in vivo and in vitro effects of Phe on DNA damage determined by the alkaline comet assay using silver staining and visual scoring. We found a dose-dependent effect of Phe on DNA damage in leukocytes from normal individuals incubated with different concentrations of Phe. Additionally, by analyzing blood leukocytes from two groups of treated PKU patients based on their blood Phe levels, we verified that the DNA damage index was significantly higher in PKU patients with high Phe blood levels (DI = 68.2 ± 12.3), compared to well-treated patients and the control group (healthy individuals). Furthermore, well-treated PKU patients had greater DNA damage (DI = 44.9 ± 7.6) relatively to controls (DI = 12.7 ± 4.1). Our present in vitro and in vivo findings indicate that DNA damage occurs in peripheral blood from PKU patients and is associated to Phe blood levels.     

DNA damage evaluated by the comet assay in lymphocytes of children with Cs internal contamination caused by the Chernobyl accident

The comet assay is one of the most versatile and popular tools for evaluating DNA damage. Its sensitivity to low dose radiation has been tested in vitro, but there are limited data showing its application and sensitivity in chronic exposure situations. The influence of the internal contamination caused by the Chernobyl accident on the level of DNA damage was evaluated by the comet assay on lymphocytes of 56 Ukrainian children. The study was performed during 2003 on children with demonstrable ¹³⁷Cs internal contamination caused by food consumption. The children were selected for the study immediately after a ¹³⁷Cs whole body counter measurement of internal contamination. The minimal detectable amount of ¹³⁷Cs was 75 Bq. The control group included 29 children without detectable internal contamination, while in the exposed group 27 children with measured activity between 80 and 4037 Bq and committed effective dose between 54 and 3155 μSv were included. Blood samples were taken by a finger prick. The alkaline version of the comet assay was used, in combination with silver stained comets and arbitrary units (AU), for comet measurement. Factors such as disease, medical treatment, surface contamination of children's living location, etc., were considered in the study. Non-significant differences (p > 0.05) in DNA damage in control (9.0 ± 5.7 AU) versus exposed (8.5 ± 4.8 AU) groups were found. These results suggest that low doses of ¹³⁷Cs internal contamination are not able to produce detectable DNA damage under the conditions used for the comet assay in this study. Further studies considering effects of high exposure should be performed on chronically exposed people using this assay.     

Resveratrol ameliorates DNA damage, prooxidant and antioxidant imbalance in 1,2-dimethylhydrazine induced rat colon carcinogenesis

Colorectal cancer is one of the most common internal malignancies in Western society. Currently oxidative stress has been increasingly postulated as a major contributor to carcinogenesis. The assessment of damage in various biological matrices, such as tissues and cells, is vital to understand the development of carcinogenesis and subsequently devising intervention strategies. Thus, the major objective of the present study was to examine the effect of resveratrol (Res) on DNA damage in a short-term study of 16 days and circulatory lipid peroxidation, enzymic/non-enzymic antioxidants status in a long-term study of 30 weeks in 1,2-dimethylhydrazine (DMH) induced colon carcinogenesis. Wistar male rats were divided into 6 groups, group 1 were control rats, group 2 rats received Res (8 mg/kg body weight, orally, everyday), rats in groups 3–6 were administered (DMH, 20 mg/kg body weight, s.c.) as four injections in order to induce DNA damage in the short-term or once a week for the first 15 weeks in the long-term study. In addition to DMH, group 4 (initiation), 5 (post-initiation) and 6 (entire-period) received Res (8 mg/kg body weight, p.o., everyday). The results revealed that, supplementation with Res (entire-period) treatment regimen significantly reduced the DMH-induced leukocytic DNA damage (tail length, tail moment, % DNA in the comet tail and olive tail moment) as compared to DMH-alone treated rats. In addition, entire-period Res supplementation increased the enzymic (superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase and glutathione S-transferase) and non-enzymic (reduced glutathione, vitamin C, vitamin E and β-carotene) antioxidant status with a corresponding decrease in the extent of lipid peroxidation markers (thiobarbituric acid reactive substances, diene conjugates and lipid hydroperoxides). Conversely, Res supplementation during initiation and post-initiation regimen did not produce greater modulatory effects. Our results indicate that DMH-induced DNA damage and oxidative stress were suppressed/prevented effectively by chronic Res supplementation.     

DNA damage in storage cells of anhydrobiotic tardigrades

In order to recover without any apparent damage, tardigrades have evolved effective adaptations to preserve the integrity of cells and tissues in the anhydrobiotic state. Despite those adaptations and the fact that the process of biological ageing comes to a stop during anhydrobiosis, the time animals can persist in this state is limited; after exceedingly long anhydrobiotic periods tardigrades fail to recover. Using the single cell gel electrophoresis (comet assay) technique to study the effect of anhydrobiosis on the integrity of deoxyribonucleic acid, we showed that the DNA in storage cells of the tardigrade Milnesium tardigradum was well protected during transition from the active into the anhydrobiotic state. Specimens of M. tardigradum that had been desiccated for two days had only accumulated minor DNA damage (2.09 ± 1.98% DNA in tail, compared to 0.44 ± 0.74% DNA in tail for the negative control with active, hydrated animals). Yet the longer the anhydrobiotic phase lasted, the more damage was inflicted on the DNA. After six weeks in anhydrobiosis, 13.63 ± 6.41% of DNA was found in the comet tail. After ten months, 23.66 ± 7.56% of DNA was detected in the comet tail. The cause for this deterioration is unknown, but oxidative processes mediated by reactive oxygen species are a possible explanation.     

Alkylation-induced genotoxicity as a predictor of DNA repair deficiency following experimental oral carcinogenesis

The aim of this study was to evaluate alkylation induced genotoxicity as a result of DNA repair deficiency during 4-nitroquinoline 1-oxide (4NQO)-induced rat tongue carcinogenesis by means of single cell gel (comet) assay. Male Wistar rats were distributed into three groups of 10 animals each and treated with 50 ppm 4NQO solution through their drinking water for 4, 12, and 20 weeks. Ten animals were used as negative control. Blood samples and oral mucosa cells collected from all animals were divided into two aliquots of 20 μL each to study basal DNA damage and DNA damage due to genotoxin sensitivity. The first aliquot was processed immediately for comet assay to assess basal DNA damage. The second aliquot was treated with a known genotoxin, methylmetanesulfonate. Significantly greater DNA damage was noticed to oral mucosa cells from 4, and 12 weeks post-treatment. Peripheral blood cells did show statistically significant differences (P < 0.05) after 20 weeks-group (squamous cell carcinoma). In conclusion, alkylation induced genotoxicity as a result of DNA repair deficiency is present in oral mucosa cells following oral experimental carcinogenesis.     

An In Vitro Study on Bacterial Growth Interactions and Intestinal Epithelial Cell Adhesion Characteristics of Probiotic Combinations

The aims of this study were to examine long-term growth interactions of five probiotic strains (Lactobacillus casei 01, Lactobacillus plantarum HA8, Lactobacillus rhamnosus GG, Lactobacillus reuteri ATCC 55730 and Bifidobacterium lactis Bb12) either alone or in combination with Propionibacterium jensenii 702 in a co-culture system and to determine their adhesion ability to human colon adenocarcinoma cell line Caco-2. Growth patterns of probiotic Lactobacillus strains were not considerably affected by the presence of P. jensenii 702, whereas lactobacilli exerted a strong antagonistic action against P. jensenii 702. In the co-culture of Bif. lactis Bb12 and P. jensenii 702, a significant synergistic influence on growth of both bacteria was observed (P < 0.05). The results of adhesion assay showed that when probiotic strains were tested in combination, there was evidence of an associated effect on percentage adherence. However, in most cases these differences were not statistically significant (P < 0.05). Adhesion percentage of Lb. casei 01 and Lb. rhamnosus GG both decreased significantly in the presence of P. jensenii 702 compared to their adhesion levels when alone (P < 0.05). These results show that the survival and percentage adhesion of some probiotic strains may be influenced by the presence of other strains and this should be considered when formulating in the probiotic products.     

Detection of oxidative DNA damage in isolated marine bivalve hemocytes using the comet assay and formamidopyrimidine glycosylase (Fpg)

Organisms in polluted areas can be exposed to complex mixtures of chemicals; however, exposure to genotoxic contaminants can be particularly devastating. DNA damage can lead to necrosis, apoptosis, or heritable mutations, and therefore has the potential to impact populations as well as individuals. Single cell gel electrophoresis (the comet assay) is a simple and sensitive technique used to examine DNA damage in single cells. The lesion-specific DNA repair enzyme formamidopyrimidine glycoslyase (Fpg) can be used in conjunction with the comet assay to detect 8-oxoguanine and other damaged bases, which are products of oxidative damage. Fpg was used to detect oxidative DNA damage in experiments where isolated oyster (Crassostrea virginica) and clam (Mercenaria mercenaria) hemocytes were exposed to hydrogen peroxide. Standard enzyme buffers used with Fpg and the comet assay produced unacceptably high amounts of DNA damage in the marine bivalve hemocytes used in this study necessitating a modification of existing methods. A sodium chloride based reaction buffer was successfully used. Oxidative DNA damage can be detected in isolated oyster and clam hemocytes using Fpg and the comet assay when the sodium chloride reaction buffer and protocols outlined here are employed. The use of DNA repair enzymes, such as Fpg, in conjunction with the comet assay expands the usefulness and sensitivity of this assay, and provides important insights into the mechanisms of DNA damage.     

Plasma homocysteine and DNA damage profiles in normal and obese subjects in the Pakistani population

Dependence of plasma total homocysteine (tHcy) and DNA damage profiles on melanodialdehyde (MDA), oxidative stress, liver function tests (LFT), and lipids was studied in non-obese and obese subjects in the Pakistani population. Development of obesity is influenced by both genetic, biochemical and environmental factors. Plasma homocysteine (Hcy) and DNA damage profiles play a pivotal role in its progression. We studied 160 obesity patients and 160 lean subjects. Leukocytes were evaluated for DNA damage by comet assay and blood plasma for biochemical properties using commercial kits. Plasma Hcy level and DNA damage were strongly correlated with triglycerides (P < 0.000), LDL-cholesterol (P < 0.001), systolic blood pressure (P < 0.001), cholesterol (P < 0.004), MDA (P < 0.004) and total oxygen stress (P < 0.004) in obese individuals. Both Hyc and DNA damage were negatively associated with total anti-oxidant response and globulin. Both Hcy profile and DNA damage may have a role in the endothelium damage even in the normal range and are related to triglycerides, ALT, MDA, TOS, HDL- and LDL-cholesterol in the Pakistani population.     

In vivo bioassay to detect irinotecan-stabilized DNA/topoisomerase I complexes in rats

Irinotecan is an anticancer agent that stabilizes topoisomerase I/DNA complexes. So far, no test system has been reported for directly determining irinotecan-induced stabilization of topoisomerase I/DNA complexes in organs in vivo. We adapted an ‘in vivo complexes of enzyme to DNA’ (ICE) bioassay to assess irinotecan activity in the stomach, duodenum, colon and liver of male Wistar rats after a single treatment with irinotecan (100 mg/kg body weight, intraperitoneally). This was compared to the control group receiving 0.9% sodium chloride intraperitoneally. In addition, the DNA strand breaking properties of irinotecan were measured in mucosal cells from the distal colon by single-cell gel electrophoresis (comet assay) to investigate the association of topoisomerase poisoning and DNA damage in vivo. A single dose of irinotecan significantly increased amounts of topoisomerase I covalently bound to DNA in stomach, duodenum, colon and liver. Concomitantly, the irinotecan-treated group showed significantly higher amounts of DNA strand breaks in colon mucosa cells compared to the control group. The ICE bioassay and the comet assay represent two test systems for investigating the impact of topoisomerase I poisons on DNA integrity in colon tissues of Wistar rats.     

Genomic damage induced in tobacco plants by chlorobenzoic acids—Metabolic products of polychlorinated biphenyls

Tobacco seedlings (Nicotiana tabacum var. xanthi) were treated for 24 h with mono-(2- and 3-CBA), di-(2,5- and 3,4-CBA), and tri-(2,4,6- and 2,3,5-CBA)-chlorobenzoic acids (CBAs) and with the mixture of polychlorinated biphenyls – Delor 103, or cultivated for 1 or 2 weeks in soil polluted with the CBAs. DNA damage in nuclei of leaves and roots was evaluated by the comet assay. A significant increase in DNA damage was observed only at concentrations of CBAs that caused withering of leaves or had lethal effects within 2–4 weeks after the treatments. As the application of CBAs did not induce somatic mutations, the induced DNA migration is probably caused by necrotic DNA fragmentation and not by DNA damage resulting in genetic alteration. In contrast, the application of the monofunctional alkylating agent ethyl methanesulphonate as a positive control resulted in a dose–response increase of DNA damage and an increase of somatic mutations. Thus, the EMS-produced DNA migration is probably associated with genotoxin-induced DNA fragmentation. The data demonstrate that the comet assay in plants should be conducted together with toxicity studies to distinguish between necrotic and genotoxin-induced DNA fragmentation. The content of 2,5-CBA in tobacco seedlings was measured by reverse-phase high pressure liquid chromatography.     

Establishment of the comet assay in the freshwater snail Biomphalaria glabrata (Say, 1818)

The single cell gel eletrophoresis or the comet assay was established in the freshwater snail Biomphalaria glabrata. For detecting DNA damage in circulating hemocytes, adult snails were irradiated with single doses of 2.5, 5, 10 and 20 Gy of ⁶⁰Co gamma radiation. Genotoxic effect of ionizing radiation was detected at all doses as a dose-related increase in DNA migration. Comet assay in B. glabrata demonstrated to be a simple, fast and reliable tool in the evaluation of genotoxic effects of environmental mutagens.     

Zinc mediated normalization of histoarchitecture and antioxidant status offers protection against initiation of experimental carcinogenesis

The present study evaluated the inhibitory effects of zinc on colonic antioxidant defense system and histoarchitecture during 1,2 dimethylhydrazine (DMH) induced colon carcinogenesis in male Sparque Dawley rats. The rats were segregated into four groups viz., normal control, DMH treated, zinc treated, DMH + zinc treated. Colon carcinogenesis was induced through weekly subcutaneous injections of DMH (30 mg/kg body weight) for 8 weeks. Zinc (in the form of zinc sulphate) was supplemented to rats at a dose level of 227 mg/l in drinking water, ad libitum for the entire duration of the study. Increased lipid peroxidation was accompanied by a decrease in reduced glutathione (GSH), glutathione reductase (GR), glutathione-s-transferase (GST), superoxide dismutase (SOD), and catalase. Administration of zinc to DMH treated rats significantly decreased the lipid peroxidation levels with simultaneous enhancement of GSH, GR, GST, SOD, and Catalase. Histopathological studies from DMH treated rats revealed disorganization of colonic histoarchitecture. However, zinc treatment to DMH treated rats greatly restored normalcy in the colonic histoarchitecture, with no apparent signs of abnormality. Energy Dispersive X-Ray Fluorescence (EDXRF) studies revealed a significant decrease in tissue concentrations of zinc in the colon following DMH treatment, which upon zinc supplementation were recovered to near normal levels. In conclusion, the results of this study suggest that zinc has a beneficial effect during the initiation of key events leading to the development of experimentally induced carcinogenesis.     

Evaluation of the genotoxicity of cadmium in gill cells of the clam <Emphasis Type="Italic">Corbicula japonica</Emphasis> using the comet assay

Cadmium-induced DNA degradation in gill cells of the clam Corbicula japonica was assessed using the comet assay (single-cell gel electrophoresis). Accumulation of highly toxic cadmium in the gill cells of bivalve is accompanied by damage to the cell genome, which is revealed as DNA migration in the comet assay. The main mechanisms of Cd effects on the integrity of the DNA structure are discussed.     

Investigating DNA damage in tannery workers occupationally exposed to trivalent chromium using comet assay

DNA damage of peripheral lymphocytes in 60 workers occupationally exposed to trivalent chromium [Cr(III)] in a tannery was studied using comet assay. The urinary and blood chromium levels were detected as a biomarker of internal exposure. The 90 subjects were divided into three groups: (i) exposure group I included 30 tannery workers highly exposed to chromium from tanning department; (ii) exposure group II included 30 tannery workers with moderate chromium exposure from finishing department; (iii) control group included 30 individuals without exposure to physical or chemical genotoxic agents. No significant difference was found among the three groups for age and smoking. The results showed that the medians of blood and urinary Cr of two exposure groups were significantly higher than those of control group (P < 0.01). And the medians of blood and urinary Cr of exposure group I were significantly higher than those of exposure group II (P < 0.05 or P < 0.01). The medians of mean tail length (MTL) of the three groups were 5.33 (2.90–8.50), 3.43 (2.31–8.29) and 2.04 (0.09–3.83) μm, respectively; The medians of mean tail moment (MTM) of the three groups were 6.28 (2.14–11.81), 3.41 (1.25–11.07) and 0.53 (0.13–3.29), respectively. The MTL and MTM of two exposure groups were significantly higher than those of control group (P < 0.01). The MTL and MTM of exposure group I were significantly higher than those of exposure group II (P < 0.01). The results of the present investigation suggest that occupational exposure to trivalent chromium can lead to a detectable DNA damage of human peripheral lymphocytes. Moreover, DNA damage was associated with chromium levels in blood. DNA damage may serve as a valuable effective biomarker and total chromium in blood may serve as a useful internal exposure biomarker in the population occupationally exposed to trivalent chromium.     

Application of Probiotics in Folate Bio-Fortification of Yoghurt

Folate deficiency is a public health concern affecting all age groups worldwide. The available evidence reveals that adding probiotic bacteria to the yoghurt starter cultures during yoghurt production process under fermentation conditions increases the folate content of yoghurt. The present study was conducted to measure two folate derivatives, i.e., 5-methyltetrahydrofolate and 5-formyltetrahydrofolate, in bio-fortified yoghurt samples including (1) yoghurt containing Streptococcus thermophilus and Lactobacillus bulgaricus, (2) probiotic yoghurt containing Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-12, (3) probiotic yoghurt containing native strains of Lactobacillus plantarum 15HN, (4) probiotic yoghurt containing native strains of Lactococcus lactis 44Lac, and (5) probiotic yoghurt containing commercial strains of Lactobacillus plantarum LAT BY PL. During storage at 4 °C for 21 days, the highest levels of 5-methyltetrahydrofolate and 5-formyltetrahydrofolate, which were statistically significant, were detected in the yoghurt made using Lact. plantarum 15HN. Moreover, the highest total folate concentration (1487 ± 96.42 μg/L) was specified in the yoghurt containing Lact. plantarum 15HN on the 7th day. It can be conjectured that this product can be suggested as a proper alternative to synthetic folic acid and may not have the side effects of using synthetic folic acid overdoses.