A short-term study of corneal collagen cross-linking with hypo-osmolar riboflavin solution in keratoconic corneas

AIM: To report the 3mo outcomes of collagen crosslinking(CXL) with a hypo-osmolar riboflavin in thin corneas with the thinnest thickness less than 400 μm without epithelium.METHODS: Eight eyes in 6 patients with age 26.2±4.8y were included in the study. All patients underwent CXL using a hypo-osmolar riboflavin solution after its de-epithelization. Best corrected visual acuity, manifest refraction, the thinnest corneal thickness, and endothelial cell density were evaluated before and 3mo after the procedure.RESULTS: The mean thinnest thickness of the cornea was 408.5 ±29.0 μm before treatment and reduced to369.8 ±24.8 μm after the removal of epithelium. With the application of the hypo-osmolar riboflavin solution, the thickness increased to 445.0 ±26.5 μm before CXL and recover to 412.5 ±22.7 μm at 3mo after treatment, P =0.659). Before surgery, the mean K-value of the apex of the keratoconus corneas was 57.6 ±4.0 diopters, and slightly decreased(54.7±4.9 diopters) after surgery(P =0.085). Mean best-corrected visual acuity was 0.55 ±0.23 logarithm of the minimal angle of resolution, and increased to 0.53±0.26 logarithm after surgery(P =0.879).The endothelial cell density was 2706.4 ±201.6 cells/mm2 before treatment, and slightly decreased( 2641. 2 ±218.2 cells/mm2) at last fellow up(P =0.002).CONCLUSION: Corneal collagen cross-linking with a hypo-osmolar riboflavin in thin corneas seems to be a promising treatment. Further study should be done to evaluate the safety and efficiency of CXL in thin corneas for the long-term.

不同添加剂对红螯螯虾幼虾室内育苗池标粗效果的影响研究

试验旨在探索不同添加剂对幼虾标粗效果的影响。选取10800尾虾,随机分为6组,每组3重复,每个重复600尾虾。1组(对照组)投喂基础饲料,2组投喂70%基础饲料+30%螺旋藻粉,3组投喂80%基础饲料+20%螺旋藻粉,4组投喂80%基础饲料+10%螺旋藻粉+3%虾青素+2%亚麻籽油+3%南极磷虾油+2%核黄素,5组投喂70%基础饲料+10%螺旋藻粉+6%虾青素+4%亚麻籽油+6%南极磷虾油+4%核黄素,6组投喂70%基础饲料+20%螺旋藻粉+3%虾青素+2%亚麻籽油+3%南极磷虾油+2%核黄素。试验期10 d。结果显示,4组、5组幼虾的成活率显著高于1组、2组(P<0.05),各组成活率排序依次为4组>5组>3组>6组>2组>1组。4组幼虾具有较高的增重率与全长增长率,各组幼虾增重率依次为4组>3组>5组=6组=2组>1组,全长增长率依次为4组>5组>3组>2组>6组>1组。4组幼虾胰蛋白酶(TPS)、超氧化物歧化酶(SOD)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)的活性均显著高于1组、2组(P<0.05)。研究表明,4组幼虾的成活率、生长速度及免疫相关酶活性均较高,即80%基础饲料+10%螺旋藻粉+3%虾青素+2%亚麻籽油+3%南极磷虾油+2%核黄素效果较好。

不同核黄素浓度与可见光光照强度对血浆中大肠杆菌的影响

目的研究不同核黄素浓度与可见光光照强度对血浆中大肠杆菌的影响,为建立血浆中污染细菌的灭活方法提供备选条件。方法随机选取谷氨酸氨基转移酶(ALT)检测不合格的新鲜冰冻血浆,按照处理方式将实验分为三大类:第一类为只添加菌液但不做任何处理的对照组,第二类为只添加菌液并接受光照处理的光照组,第三类为添加菌液与核黄素并接受光照处理的实验组。其中实验组根据核黄素浓度又细分为50、100、150和300μM的核黄素浓度组。光照组和各核黄素浓度组分别接受420 nm可见光的光照处理,每轮光照的光照强度分别为50 mW/cm^(2)、75 mW/cm^(2)和100 mW/cm^(2),光照时间为55 min(分别在25、35、45和55 min取样检测),光照结束后通过细菌培养评估不同核黄素浓度与可见光光照强度对血浆中大肠杆菌的影响。结果在420 nm光照55 min后,各核黄素浓度下大肠杆菌浓度分别下降了1.7~3.5 log(50 mW/cm^(2)),2.8~≥4.4 log(75 mW/cm^(2)),4.0~≥4.7 log(100 mW/cm^(2))。其中,高强度的光照(100 mW/cm^(2))协同高浓度的核黄素(150μM和300μM)能够有效降低血浆中大肠杆菌的浓度达到4 log以上。而光照强度的增加与核黄素浓度升高也会增加对大肠杆菌的处理效果,两者与大肠杆菌处理效果之间也呈正相关。结论在420 nm波长、光照强度75 mW/cm^(2)、核黄素浓度为150μM和300μM时,核黄素可见光照射方法对血浆中大肠杆菌具有最理想的处理效果,可有效降低血浆中污染的大肠杆菌浓度。

角膜基质透镜联合跨上皮快速角膜胶原交联术治疗重度圆锥角膜

目的:评估角膜基质透镜联合跨上皮快速角膜胶原交联术(SC-A-TE-CXL)治疗重度圆锥角膜的临床疗效。方法:前瞻性自身前后对照研究。收集2019-03/2022-07于南京医科大学附属眼科医院确诊为重度圆锥角膜且最薄点角膜厚度(含上皮)<400μm的患者10例14眼,其中男8例12眼,女2例2眼,予以SC-A-TE-CXL进行治疗。观察并记录术前和术后1、3、6、12 mo的角膜曲率、裸眼视力(UCVA)、最佳矫正视力(BCVA)、角膜最薄点厚度(TCT)、角膜中心厚度(CCT)、非接触式眼压、内皮细胞密度(ECD)和前后表面最薄点高度以及术后1 mo角膜交联深度。结果:患者行SC-A-TE-CXL术后1、3、6、12 mo UCVA和BCVA较术前提高,但总体无差异(F=0.793,P=0.535;F=0.783,P=0.542)。术后各时间点K1、K2、Km和Kmax较术前下降,但总体无差异(F=0.627,P=0.574;F=1.264,P=0.296;F=0.727,P=0.520;F=1.115,P=0.359)。术后各时间点前后表面最薄点高度较术前均下降,但总体无差异(F=1.046,P=0.359;F=1.164,P=0.337)。术后各时间点非接触式眼压较术前提高,但总体无差异(F=0.814,P=0.522)。术后各时间点CCT、TCT和术前相比总体无差异(F=0.931,P=0.453;F=0.782,P=0.542)。术后12 mo ECD与术前相比无差异(t=1.266,P=0.228)。术后1 mo,前节光学相干层析成像术(AS-OCT)显示角膜浅层基质密度增高,前后基质间存在“分界线”,平均深度为124.07±25.13μm。结论:SC-A-TE-CXL能延缓重度圆锥角膜患者的病情进展,安全性高,其远期疗效有待进一步观察,可以作为一种治疗重度圆锥角膜的手术方式。

核黄素强化IFAS工艺脱氮同步降解布洛芬研究

城市污水厂中传统脱氮工艺脱氮效果差以及对药物及个人护理品(pharmaceutical and personal care products,PPCPs)降解效率低,导致出水氮超标的同时频繁检出PPCPs.以布洛芬(ibuprofen,IBP)作为典型PPCPs,以泡沫炭作为微生物及核黄素载体,以核黄素作为氧化还原介体强化生物膜-活性污泥组合(integrated fixed-film activated sludge,IFAS)工艺脱氮同步降解IBP,并探究其作用机理.结果表明,微氧条件下,脱氮与IBP降解能够同步进行,碳氮比(COD/NO_(3)^(-)-N)为4∶1、水力停留时间为6 h时核黄素强化反应器(R2)中硝氮平均去除率及IBP平均降解率相较于空白对照反应器(R1)分别提高了36%和25%.机理研究表明,R2中核黄素促进了脱氢酶与反硝化酶的活性,生物膜的脱氢酶、硝酸盐还原酶和亚硝酸盐还原酶活性平均值分别较R1提高了35%、14%、35%,从而实现了核黄素强化IFAS工艺脱氮同步降解布洛芬.

Impact of increasing one-carbon metabolites on traumatic brain injury outcome using pre-clinical models

Traumatic brain injury is a major cause of death and disability worldwide,affecting over 69 million individuals yearly.One-carbon metabolism has been shown to have beneficial effects after brain damage,such as ischemic stroke.However,whether increasing one-carbon metabolite vitamins impacts traumatic brain injury outcomes in patients requires more investigation.The aim of this review is to evaluate how one-carbon metabolites impact outcomes after the onset of traumatic brain injury.PubMed,Web of Science,and Google Scholar databases were searched for studies that examined the impact of B-vitamin supplementation on traumatic brain injury outcomes.The search terms included combinations of the following words:traumatic brain injury,dietary supplementation,one-carbon metabolism,and B-vitamins.The focus of each literature search was basic science data.The year of publication in the literature searches was not limited.Our analysis of the literature has shown that dietary supplementation of B-vitamins has significantly improved the functional and behavioral recove ry of animals with traumatic brain injury compared to controls.Howeve r,this improvement is dosage-dependent and is contingent upon the onset of supplementation and whether there is a sustained or continuous delive ry of vitamin supplementation post-traumatic brain injury.The details of supplementation post-traumatic brain injury need to be further investigated.Overall,we conclude that B-vitamin supplementation improves behavioral outcomes and reduces cognitive impairment post-traumatic brain injury in animal model systems.Further investigation in a clinical setting should be stro ngly considered in co njunction with current medical treatments for traumatic brain injury-affected individuals.

Effects of nicotinamide and riboflavin on the biodesulfurization activity of dibenzothiophene by Rhodococcus erythropolis USTB-03

Rhodococcus erythropolis USTB-03 is a promising bacterial strain for the biodesulfurization of dibenzothiophene （DBT） via a sulfurspecific pathway in which DBT is converted to 2-hydroxybiphenyl （2HBP） as an end product. The effects of nicotinamide and riboflavin on the sulfur specific activity （SA） of DBT biodesulfurization by R. erythropolis USTB-03 were investigated. Both nicotinamide and riboflavin were found to enhance the expression of SA, which was not previously reported. When R. erythropolis USTB-03 was grown on a medium containing nicotinamide of 10.0 mmol or riboflavin of 50.0 μmol, SA was raised from 68.0 or so to more than 130 mmol 2HBP/（kg dry cells.h）. When R. erythropolis USTB-03 was grown in the presence of both nicotinamide of 5.0 mmol and riboflavin of 25.0 μmol, SA was further increased to 159.0 mmol 2HBP/（kg dry cells.h）. It is suggested that the biological synthesis of reduced form of flavin mononucleotide （FMNH2）, an essential coenzyme for the activities of biodesulfurization enzyme Dsz C and A, might be enhanced by nicotinamide and riboflavin, which was responsible for the increased SA of R. erythropolis USTB-03.

Synthesis of highly fluorescent carbon dots from lemon and onion juices for determination of riboflavin in multivitamin/mineral supplements

In this work, lemon and onion biomasses commonly found in street markets are for the first time used to develop a facile, fast and low-cost one-step microwave-assisted carbonization method for synthesis of highly fluorescent carbon dots (CDs). The structure and optical properties of CDs were investigated by TEM, XRD, XRF, UV-Vis, FTIR, and fluorescence spectroscopy. CDs displayed satisfactory optical pro-prieties, a high quantum yield of 23.6%, and excellent water solubility, and the particle size was 4.23-8.22 nm with an average diameter of 6.15 nm. An efficient fluorescent resonance energy transfer (FRET) between the CDs and riboflavin was achieved with CDs acting as donor and riboflavin as acceptor. A linear relationship between FRET and the riboflavin concentration from 0.10 to 3.0 μg/mL was observed, allowing the development of an accurate and fast analytical method to determine this vitamin in multivitamin/mineral supplements. Despite the potential interferences in these supplements, CDs were selective for riboflavin under optimized conditions. A paired t-test at a 95% confidence level indicated no statistically significant difference between the proposed and the reference methods. Recovery test presented values ranged from 96.0% to 101.4%. The limit of detection and relative standard deviation were estimated at 1.0 ng/mL and <2.6% (n = 3), respectively. CDs were successfully synthesized in a domestic microwave oven (1450 W, 6 min), presenting satisfactory parameters when compared with results of other studies reported in the literature, suggesting that the proposed method is a potentially useful method for the synthesis of CDs and determination of riboflavin.

Evaluation of the in vitro antimicrobial properties of ultraviolet A/riboflavin mediated crosslinking on Candida albicans and Fusarium solani

AIMTo evaluate the antimicrobial properties of ultraviolet A (UVA) (365 nm)/riboflavin against Candida albicans and Fusarium solani.

Highly Sensitive Spectrofluorimetric Determination of Riboflavin Based on the Generation of Active Oxygen Coupled with Enzymatic Reaction

A spectrofluorimetric method for the determining riboflavin (VB2) based on its enhancement on the fluorescence of hemoglobin-catalyzed enzymatic reaction was proposed. The proposed method consisted of two reactions. One was the photochemical reaction of VB2, the other was a hemoglobin-catalyzed enzymatic reaction. The optimal experimental conditions for the determinations were established. The linear range of the method was 5.0×10?9?1.0×10?7 mol/L of VB2. The detection limit was calculated to be 3.65×10?9 mol/L. The relative standard deviation of this method was 2.3%at 7.0×10?2 mol/L for 11 determinations.

Iontophoresis-assisted corneal crosslinking using 0.1% riboflavin for progressive keratoconus

AIM：To report the clinical results of iontophoresis-assisted epithelium-on corneal crosslinking（I-CXL） using 0.1% riboflavin in distilled water for progressive keratoconus. METHODS：In this prospective clinical study, we examined 94 eyes of 75 patients with progressive keratoconus who were treated with I-CXL using 0.1% riboflavin in distilled water. Best correct visual acuity（BCVA）, Scheimpflug tomography, corneal topography, anterior segment optical coherence tomography, intraocular pressure, and endothelial cell density were evaluated at baseline and 1, 3, 6, 12, and 24 mo after I-CXL.RESULTS：After 24 mo I-CXL, compared to the level at baseline, BCVA significantly improved 0.14±0.07（P=0.010）; mean keratometry signifi cantly decreased 0.72±1.97（P=0.021）; maximum keratometry significantly reduced 2.30±5.01（P=0.014）; central keratoconus index significantly reduced 0.04±0.08（P=0.007）. The demarcation line was visible in 83.1% of eyes at 1mo after treatment, with a depth of 298.95±51.97 μm, and gradually indistinguishable. One eye had repeat treatment. Intraocular pressure and endothelial cell density did not change significantly.CONCLUSION：I-CXL using 0.1% riboflavin halts keratoconus progression within 24 mo, resulting in a significant improvement in visual and topographic parameters. Moreover, the depth of the demarcation line is similar to that previously reported in standard epithelium-off CXL procedures.

Decreased blood riboflavin levels are correlated with defective expression of RFT2 gene in gastric cancer

AIM:To investigate the relationship between blood riboflavin levels and riboflavin transporter 2(RFT2) gene expression in gastric carcinoma(GC) development.METHODS:High-performance liquid chromatography was used to detect blood riboflavin levels in patients with GC.Real-time fluorogenic quantitative polymerase chain reaction and immunohistochemistry were used to analyze the expression of RFT2 mRNA and protein in samples from 60 GC patients consisting of both tumor and normal tissue.RESULTS:A significant decrease in the RFT2 mRNA levels was detected in GC samples compared with those in the normal mucous membrane(0.398 ± 0.149 vs 1.479 ± 0.587;P = 0.040).Tumors exhibited low RFT2 protein expression(75%,16.7%,8.3% and 0% for no RFT2 staining,weak staining,medium staining and strong staining,respectively),which was significantly lower than that in the normal mucous membrane(10%,16.7%,26.7% and 46.7% for no RFT2 staining,weak staining,medium staining and strong staining,respectively;P < 0.05).Tumors with low RFT2 expression were significantly associated with tumor stage and histological grade.Moreover,a significantly decrease in Uyghur patients was observed compared with Han patients.However,other parameters-gender,tumor location and lymph node metastasis-showed no significant relationship with RFT2 expression.Blood riboflavin levels were reverse correlated with development of GC(1.2000 ± 0.97 569 ng/mL in high tumor stage patients vs 2.5980 ± 1.31 129 ng/mL in low tumor stage patients;P < 0.05).A positive correlation of plasma riboflavin levels with defective expression of RFT2 protein was found in GC patients(2 = 2.619;P = 0.019).CONCLUSION:Defective expression of RFT2 is associated with the development of GC and this may represent a mechanism underlying the decreased plasma riboflavin levels in GC.

Iontophoretic Delivery of Riboflavin into the Rabbit Cornea:a Primary Study

Purpose: To determine the penetrability of riboflavin into the corneal stroma by iontophoresis and to compare the permeability effects of different solvents.Methods: Twenty rabbits were randomly divided into four groups: a group that received 0.1% riboflavin-balanced salt solution(BSS) by iontophoresis, a group that received 0.1%riboflavin-saline solution by iontophoresis, a group that received 0.1% riboflavin-distilled water solution by iontophoresis, and a control group that received classical riboflavin instillation after corneal de-epithelialization. The degree of yellowing of the de-epithelialized corneal stromal button from each rabbit was compared.Results: The yellow color scores for the corneal stromal buttons in the three iontophoresis groups were compared with those of control group. Iontophoretic delivery of a 0.1% riboflavin-distilled water solution yielded similar yellow changes in the corneal stromal button when compared with classical riboflavin instillation after de-epithelialization. However, the other two solvents did not sufficiently enhance the permeability of riboflavin.Conclusion: Riboflavin can effectively penetrate into the corneal stroma to saturation levels by iontophoresis. Using distilled water as the solvent can promote penetrability.

Enhanced Riboflavin Production by Expressing Heterologous Riboflavin Operon from B.cereus ATCC14579 in Bacillus subtilis

Fragment containing the whole riboflavin(rib)operons of B.cereus ATCC14579 was detected from GenBank and annotated.The rib operon of ATCC14579 was cloned with Pn,its native promoter,or with P43,the vegetative growth promoter,into the plasmid.Expression analysis showed that heterologous rib operon was operative in B.subtilis.Integrative plasmid with P43-rib fragment was integrated into the chromosome of B.subtilis RH33,yielding transformant B.subtilis PY.With optimized medium components,4.3 g·L -1 of riboflavin was achieved in batch culture of B.subtilis PY,which was 27%enhancement compared to the host strain.Real-time reverse transcription polymerase chain reaction(RT-PCR)analysis indicated that the transcriptional level of ribA maintained 2.8-fold higher with the expression of herterologous rib operon.Furthermore,the stability of B.subtilis PY was increased form 45%to 87%.The high transcriptional level of rib gene and higher stability of B.subtilis PY could explain the increased riboflavin production.

Sociodemographic Factors Associated with Dietary Intake of Thiamine, Riboflavin, and Niacin among Chinese Adults in 2015

Objective To estimate the association between three B-vitamin intakes and sociodemographic factors among adults in China.Methods We derived our data from the China Health and Nutrition Survey(CHNS) among 12,241 individuals aged 18–64 years. Log binomial regression was used to estimate adjusted prevalence ratios for factors associated with the inadequate intake of B-vitamins.Results Females with low incomes and living in the north had a higher prevalence of inadequate riboflavin intake than those with high incomes and living in the south. Both males and females living in a village had a higher prevalence of inadequate riboflavin intake than adults living in a city. Adults with low income, low education, and living in the north or in a village had a higher prevalence of inadequate niacin intake than adults with a high income, high education, and living in the south or in a city.Conclusion We found that income, region, and area of residence were associated with riboflavin intake. Education, income, region, and area of residence were associated with niacin intake. Welltailored strategies and policies are needed to improve nutritional status in China.

Evaluation of corneal endothelium after UVA/riboflavin cross-linking in thin keratoconic corneas

Dear Sir,UVA/riboflavin cross-linking （CXL） has been used clinically applied for the treatment of keratoconus and corneal edema via enhancement of corneal stiffness The safety of the corneal endothelium is of prime importance during CXL treatment. In clinical practice, a corneal thickness （CT） of 400um has traditionally been regarded as the minimum treatable thickness, thereby avoiding damage to the corneal endothelium Although CXL has been applied to thinner corneas, using a hypoosmotic solution onto cornea and inducing edema . CXL safety still needs further evaluation because of lower relative concentration of collagen in the hydrated stroma . This study aims to evaluate the changes of corneal endothelial density （ECD） in cases where the CT is 〈400 um before iatrogenic corneal swelling and CXL treatment.

Effect of Riboflavin Operon Dosage on Riboflavin Productivity in Bacillus Subtilis

After deregulating the purine and riboflavin synthesis in the Gram-positive bacterium Bacillus subtilis,it is critical to amplify riboflavin operon with appropriate dosage in the host strain for remarkable increase of riboflavin production.Bacillus subtilis RH13, a riboflavin-producing strain, was selected as host strain in the construction of engineering strains by protoplast fusion. The integrative plasmid pRB63 and autonomous plasmid pRB49, pRB62 containing riboflavin operon of B.subtilis 24 were constructed and transformed into the host strain respectively. Increasing one operon copy in B.subtilis RH13 results in about 0.4 g/L improvement in riboflavin yield and the appropriate number of operon copies was about 7—8. Amplifying more riboflavin operons is of no use for further improvement of yield of riboflavin. Furthermore, excessive operon dosage results in metabolic unbalance and is fatal to the host cells producing riboflavin.

RADIATION EFFECT ON BIOSYNTHESES OF ASCORBIC ACID AND RIBOFLAVIN IN GERMINATING CHICKPEA

The influence of irradiation on biosyntheses of ascorbic acid and riboflavin in germinating chickpea seeds at ambient (25-35℃) conditions, was investigated. The rate of syntheses of these vitamins significantly increased with increasing germination time upto 120 h depending upon the treatment (P【0.05). Maximum amounts of ascorbic acid, 22.32 and 16.84 mg/100g, were found in the 0.10 kGy sample after 120 h of germination in tap and distilled water respectively. However, a radiation dose of 0.15 kGy resulted in the development of maximum values of riboflavin, 11.40 and 11.38 μ g/g, on germination in tap and distilled water respectively. A significant linear relation (r = 0-954 to 0.997) was observed between the biosyntheses of these vitamins and the germination time upto 120 h of irradiated and unirradiated chickpea seed (P【0.05).

Riboflavin concentration in corneal stroma after intracameral injection

AIM: To evaluate the enrichment of riboflavin in the corneal stroma after intracameral injection to research the barrier ability of the corneal endothelium to riboflavin in vivo.METHODS: The right eyes of 30 New Zealand white rabbits were divided into three groups. Different concentrations riboflavin-balanced salt solutions(BSS)were injected into the anterior chamber(10 with 0.5%, 10 with 1%, and 10 with 2%). Eight corneal buttons of 8.5mm in diameter from each group were dissected at 30 min after injection and the riboflavin concentrations in the corneal stroma were determined using high-performance liquid chromatography(HPLC) after removing the epithelium and endothelium. The other two rabbits in every group were observed for 24 h and sacrificed. As a comparison, the riboflavin concentrations from 16 corneal stromal samples were determined using HPLC after instillation of 0.1% riboflavin-BSS solution for30 min on the corneal surface(8 without epithelium and 8with intact epithelium).RESULTS: The mean riboflavin concentrations were11.19, 18.97, 25.08, 20.18, and 1.13 μg/g for 0.5%, 1%, 2%,de-epithelialzed samples, and the transepithelial groups,respectively. The color change of the corneal stroma and the HPLC results showed that enrichment with riboflavin similar to classical de-epithelialized corneal collagen crosslinking(CXL) could be achieved by intracameral 1%riboflavin-BSS solution after 30min; the effect appeared to be continuous for at least 30 min.CONCLUSION: Riboflavin can effectively penetrate the corneal stroma through the endothelium after an intracameral injection in vivo, so it could be an enhancing method that could improve the corneal riboflavin concentration in transepithelial CXL.

Effects of Riboflavin Interactions with 5-Methyltetrahydrofolate and Tetrahydrofolate on Changes in Homocysteine and Folate Derivative Levels, with and without Methionine Addition

Riboflavin has been suggested to act with folate to lower homocysteine (Hcy). However, these interactions may differ among the several known forms of folate. Therefore, we examined the effects of riboflavin interactions with 5-methyltetrahydrofolate (5-MTHF) and tetrahydrofolate (THF) on changes in Hcy and folate derivative levels, under conditions with and without methionine addition. Rat hepatocytes were cultured for 48 hours in medium with or without 2.64 μM riboflavin addition, under the following conditions: 1) without the addition of either methionine or folate;2) with addition of 2 μM folate derivatives [(A): 5-MTHF, (B): THF];3) with addition of both 5 mM methionine and 2 μM folate derivatives [(A): 5-MTHF, (B): THF]. The supernatants were collected at 0, 24, and 48 hours for Hcy and folate derivative measurements. The Hcy lowering effect of 5-MTHF, as well as inhibition of 5-MTHF reduction and THF elevation, appeared to be enhanced by riboflavin addition. THF addition did not lower the Hcy level, regardless of the presence of riboflavin and/or methionine, while THF and 5,10-methenyl THF levels were maintained. Further examination is needed to elucidate the interactive effects of riboflavin and folate derivatives on Hcy and folate metabolism.