Dietary Compound Chrysin Inhibits Retinal Neovascularization with Abnormal Capillaries in db/db Mice

Investigation of the antioxidant effect of Chrysin in an experimental cataract model created in chick embryos

PURPOSE

Cataract, which occurs as a result of lens opacification, is one of the most common causes of vision loss. In the literature, deterioration of the antioxidant system due to the increase in reactive oxygen species and oxidant levels is shown among the causes of cataract formation. The aim of this study was to investigate the antioxidant effect of chrysin on steroid-induced cataract development in an experimental chick embryo model using morphological, histological and biochemical parameters.

METHODS

Within the scope of the study, 150 specific pathogen free (SPF) fertilized eggs were used. Eggs were divided into 6 groups as control (group 1), corn oil (group 2), hydrocortisone hemisuccinate sodium (HC) (group 3), low dose chrysin (group 4), medium dose chrysin (group 5) and high dose chrysin (group 6). On the 15th day of incubation, Chrysin and HC were applicated to the air sac of the eggs with Hamilton and/or insulin injector. On day 17, the chick embryos were removed from the eggs and the bulbus oculi of the embryos were dissected. Lenses of 9 embryos were used for morpholigical cataract grading in each group, lens of 8 embryos for biochemical analysis and intact eyes of 7 embryos for histological evaluation (TUNEL method).

RESULTS

No opacity was observed in any of the lenses in Group 1 and 2. Cataract was observed in all lenses in Group 3. The mean opacity grades in group 3 were statistically significantly higher when compared to group 1 and 2 (p<0.05). The difference between group 6 and group 3 was statistically significant (p<0.05). GSH and TAS levels in the lenses were statistically significantly decreased compared to the control group due to HC application (p<0.05). It was determined that the decreased GSH and TAS levels in the lenses increased in relation to the Chrysin application doses. The increased levels of MDA, TOS, caspase 3 and caspase 9 in the HC group decreased significantly depending to the chrysin doses (p<0.05). In addition, while the rate of apoptotic cells determined by the TUNEL method was statistically significantly higher in the HC administered group than in the control group (p<0.05), it was statistically significantly decreased in the chrysin-administered groups, in relation to the dose of chrysin (p<0.05).

CONCLUSIONS

We think that anti-cataract effect of crhysin may be due to the antioxidant and antiapoptotic properties of chrysin. However, more research is needed to clarify the anti-cataract effects of chrysin.

Assessment of Inner Blood-Retinal Barrier: Animal Models and Methods

Proper functioning of the neural retina relies on the unique retinal environment regulated by the blood-retinal barrier (BRB), which restricts the passage of solutes, fluids, and toxic substances. BRB impairment occurs in many retinal vascular diseases and the breakdown of BRB significantly contributes to disease pathology. Understanding the different molecular constituents and signaling pathways involved in BRB development and maintenance is therefore crucial in developing treatment modalities. This review summarizes the major molecular signaling pathways involved in inner BRB (iBRB) formation and maintenance, and representative animal models of eye diseases with retinal vascular leakage. Studies on Wnt/β-catenin signaling are highlighted, which is critical for retinal and brain vascular angiogenesis and barriergenesis. Moreover, multiple in vivo and in vitro methods for the detection and analysis of vascular leakage are described, along with their advantages and limitations. These pre-clinical animal models and methods for assessing iBRB provide valuable experimental tools in delineating the molecular mechanisms of retinal vascular diseases and evaluating therapeutic drugs.

Highly water-soluble diacetyl chrysin ameliorates diabetes-associated renal fibrosis and retinal microvascular abnormality in db/db mice

BACKGROUND/OBJECTIVES

Chronic or intermittent hyperglycemia is associated with the development of diabetic complications. Oxidative stress and inflammation can be altered by hyperglycemia in diverse tissues, including kidneys and eyes, and play a pivotal role in diabetic complications. Our previous studies showed that the water-insoluble 5,7-dihydroxyflvone chrysin effectively combats diabetic damages incurred in diabetic kidneys and retinas. The current study employed the newly-synthesized 5.7-di-O-acetylchrysin, having higher solubility than chrysin, to compare the effects on diabetes-associated renal fibrosis and abnormal retinal neovascularization.

MATERIALS/METHODS

In the in vivo study, db/db mice as animal models of type 2 diabetes were orally administrated 10 mg/kg BW diacetylchrysin, daily for 10 weeks.

RESULTS

Unlike chrysin, oral administration of 10 mg/kg diacetylchrysin did not lower the blood glucose level and 24 h urine volume in db/db mice. Nevertheless, the urinary albumin excretion was markedly reduced. The administration of diacetylchrysin also diminished the deposition of collagen fibers in diabetic glomeruli and tubules by suppressing the induction of connective tissue growth factor and collagen IV in diabetic kidneys. Supplying diacetylchrysin enhanced the membrane type-1 matrix metalloproteinase (MMP) expression reduced in diabetic kidneys, while the tissue inhibitor of MMP-2 induction was attenuated in diacetylchrysin-challenged diabetic kidneys. In addition, supplementing diacetylchrysin to diabetic mice ameliorated renal injury due to glomerulosclerosis and tubular interstitial fibrosis. Furthermore, the reduced retinal inductions of Zonula occludens-1 and vascular endothelial cadherin in db/db mice were elevated in the retinal tissues of diacetylchrysin-treated animals. Oral administration of diacetylchrysin curtailed the induction of vascular endothelial growth factor (VEGF) and VEGF receptor 2 in db/db mice, ultimately retarding diabetes-associated retinal neovascularization. Additionally, the retinal formation of acellular capillaries with leaky vessels was reduced in diacetylchrysin-treated db/db mice.

CONCLUSION

Diacetylchrysin may act as a potent pro-health agent for treating renal fibrosis-associated diabetic nephropathy and retinal neovascularization-associated diabetic retinopathy.

Chrysin promotes angiogenesis in rat hindlimb ischemia: Impact on PI3K/Akt/mTOR signaling pathway and autophagy

Limb ischemia occurs due to obstruction of blood perfusion to lower limbs, a manifestation that is associated with peripheral artery disease (PAD). Angiogenesis is important for adequate oxygen delivery. The present study investigated a potential role for chrysin, a naturally occurring flavonoid, in promoting angiogenesis in hindlimb ischemia (HLI) rat model. Rats were allocated into four groups: (1) sham-operated control, (2) HLI: subjected to unilateral femoral artery ligation, (3) HLI + chrysin: received 100 mg/kg, i.p. chrysin immediately after HLI, and (4) HLI + chrysin + rapamycin: received 6 mg/kg/day rapamycin i.p. for 5 days then subjected to HLI and dosed with 100 mg/kg chrysin, i.p. Rats were killed 18 h later and gastrocnemius muscles were collected and divided into parts for (1) immunohistochemistry detection of CD31 and CD105, (2) qRT-PCR analysis of eNOS and VEGFR2, (3) colorimetric analysis of NO, (4) ELISA estimation of TGF-β, VEGF, ATG5 and Beclin-1, and (5) Western blot analysis of p-PI3K, PI3K, p-Akt, Akt, p-mTOR, mTOR, and HIF-1α. Chrysin significantly enhanced microvessels growth in HLI muscles as indicated by increased CD31 and CD105 levels and decreased TGF-β. Chrysin's proangiogenic effect is potentially mediated by increased VEGF, VEGFR2 and activation of PI3K/AKT/mTOR pathway, which promoted eNOS and NO levels as it was reversed by the mTOR inhibitor, rapamycin. Chrysin also inhibited autophagy as it decreased ATG5 and Beclin-1. The current study shows that chrysin possesses a proangiogenic effect in HLI rats and might be useful in patients with PAD.

Nature against Diabetic Retinopathy: A Review on Antiangiogenic, Antioxidant, and Anti-Inflammatory Phytochemicals

Background and Purpose. Diabetes mellitus (DM), hyperglycemia, and hypertension can result in diabetic retinopathy (DR), which is a major cause of blindness on a global scale. Development of DR is associated with decreased endothelial cells, increased basal membrane thickness, permeation of the retinal blood barrier, and neovascularization in patients. The purpose of the present review is to provide an overview of the findings regarding applications of phytochemicals for DR treatment and could be a beneficial resource for further clinical studies and also a basis for pharmaceutical purposes for drug design. Materials and Methods. A narrative literature review was performed from electronic databases including Web of Science, PubMed, and Scopus to analyze the effects of different phytochemicals to prevent or treat oxidation, angiogenesis, and inflammation in diabetic retinopathy. The inclusion criteria were original studies, which included the effects of different phytochemicals on diabetic retinopathy. The exclusion criteria included studies other than original articles, studies which assessed the effects of phytochemicals on nondiabetic retinopathy, and studies which used phytochemical-rich extracts. Results and Conclusions. Studies have shown that increased levels of inflammatory cytokines, angiogenic, and oxidative stress factors are involved in the progression and pathogenesis of DR. Therefore, phytochemicals with their anti-inflammatory, antiangiogenic, and antioxidant properties can prevent DR progression and retinal damage through various cellular mechanisms. It is also shown that some phytochemicals can simultaneously affect the inflammation, oxidation, and angiogenesis in DR.

Role of pericytes in diabetic angiogenesis

ABSTRACT

In the context of diabetes mellitus, various pathological changes cause tissue ischemia and hypoxia, which can lead to the compensatory formation of neovascularization. However, disorders of the internal environment and dysfunctions of various cells contribute to the dysfunction of neovascularization. Although the problems of tissue ischemia and hypoxia have been partially solved, neovascularization also causes many negative effects. In the process of small blood vessel renewal, pericytes are extremely important for maintaining the normal growth and maturation of neovascularization. Previously, our understanding of pericytes was very limited, and the function of pericytes was not yet clear. Recently, multiple new functions of pericytes have been identified, affecting various processes in angiogenesis and relating to various diseases. Therefore, the importance of pericytes has gradually become apparent. This article presents the latest research progress on the role of pericytes in diabetic angiogenesis, characterizes pericytes, summarizes various potential therapeutic targets, and highlights research directions for the future treatment of various diabetes-related diseases.

Animal models of diabetic retinopathy

The retina is the posterior neuro-integrated layer of the eye that conducts impulses induced by light to the optic nerve for human vision. Diseases of the retina often leads to diminished vision and in some cases blindness. Diabetes mellitus (DM) is a worldwide public health issue and globally, there is an estimated 463 million people that are affected by DM and its consequences. Diabetic retinopathy (DR) is a blinding complication of chronic uncontrolled DM and is the most common cause of blindness in the United States between the ages 24-75. It is estimated that the global prevalence of DR will increase to 191.0 million by 2030, of those 56.3 million possessing vision-threatening diabetic retinopathy (VTDR). For the most part, current treatment modalities control the complications of DR without addressing the underlying pathophysiology of the disease. Therefore, there is an unmet need for new therapeutics that not only repair the damaged retinal tissue, but also reverse the course of DR. The key element in developing these treatments is expanding our basic knowledge by studying DR pathogenesis in animal models of proliferative and non-proliferative DR (PDR and NPDR). There are numerous models available for the research of both PDR and NPDR with substantial overlap. Animal models available include those with genetic backgrounds prone to hyperglycemic states, immunologic etiologies, or environmentally induced disease. In this review we aimed to comprehensively summarize the available animal models for DR while also providing insight to each model's ocular therapeutic potential for drug discovery.

Chrysin Reduces Oxidative Stress but Does Not Affect Polyol Pathway in the Lenses of Type 1 Diabetic Rats

Prolonged hyperglycemia is one of the main causes of reactive oxygen species and free radicals generation in diabetes which may affect various organs, including the eye. Oxidative damage to proteins and lipids in the eye lens could lead to cataract formation. To cope with oxidative stress, the endogenous antioxidative system may be supported by the supplementation of exogenous antioxidants. The aim of this study was to evaluate the effect of chrysin, a natural flavonoid, on oxidative stress and polyol pathway-related markers in the lenses of streptozotocin-induced type 1 male diabetic rats. Chrysin at doses of 50 and 100 mg/kg was administered by gavage for 28 days. This treatment resulted in a decrease in antioxidative enzymes activity and oxidative stress index. Moreover, chrysin administration elevated the reduced glutathione level in the lenses. A decrease in the markers linked to oxidative damage to proteins and lipids in the lenses was noted, especially after treatment with 50 mg/kg of chrysin. Neither of the chrysin doses affected glycemia-related markers in the serum or altered parameters related to the polyol pathway and advanced glycation end-products level in the lenses of diabetic rats. Upon obtaining results, it can be concluded that chrysin reveals antioxidative activity in the lenses but shows no antihyperglycemic or antiglycation properties.

Relationships Between Neurodegeneration and Vascular Damage in Diabetic Retinopathy

Diabetic retinopathy (DR) is a common complication of diabetes and constitutes a major cause of vision impairment and blindness in the world. DR has long been described exclusively as a microvascular disease of the eye. However, in recent years, a growing interest has been focused on the contribution of neuroretinal degeneration to the pathogenesis of the disease, and there are observations suggesting that neuronal death in the early phases of DR may favor the development of microvascular abnormalities, followed by the full manifestation of the disease. However, the mediators that are involved in the crosslink between neurodegeneration and vascular changes have not yet been identified. According to our hypothesis, vascular endothelial growth factor (VEGF) could probably be the most important connecting link between the death of retinal neurons and the occurrence of microvascular lesions. Indeed, VEGF is known to play important neuroprotective actions; therefore, in the early phases of DR, it may be released in response to neuronal suffering, and it would act as a double-edged weapon inducing both neuroprotective and vasoactive effects. If this hypothesis is correct, then any retinal stress causing neuronal damage should be accompanied by VEGF upregulation and by vascular changes. Similarly, any compound with neuroprotective properties should also induce VEGF downregulation and amelioration of the vascular lesions. In this review, we searched for a correlation between neurodegeneration and vasculopathy in animal models of retinal diseases, examining the effects of different neuroprotective substances, ranging from nutraceuticals to antioxidants to neuropeptides and others and showing that reducing neuronal suffering also prevents overexpression of VEGF and vascular complications. Taken together, the reviewed evidence highlights the crucial role played by mediators such as VEGF in the relationship between retinal neuronal damage and vascular alterations and suggests that the use of neuroprotective substances could be an efficient strategy to prevent the onset or to retard the development of DR.

Chrysin: Pharmacological and therapeutic properties

Chrysin is a promising phytochemical that is categorized under the class of flavonoids based on its chemical structure. Naturally, it is widely present in propolis, honey, passion fruit, and even in mushrooms and other plant sources, whereas its synthetic counterparts are also being employed for pharmacological purposes. It has widely been employed in treatment of various degenerative disorders and provides cytotoxic and anti-inflammatory functions. Its antioxidant and disease preventing abilities are attributed to its structural diversity arising in ring-A and absence of oxygenation in B and C ring. In this review, the scientific studies are being reported emphasizing benefits and its allied health claims on chrysin in numerous metabolic malfunctions.

The Anti-Inflammatory Effects of CXCR5 in the Mice Retina following Ischemia-Reperfusion Injury

Object

Retinal ischemia-reperfusion (I/R) injury is a common pathological process in many ophthalmic diseases; there are no effective therapeutic approaches available currently. Increasing evidence indicates that microglia mediated neuroinflammation plays an important role in the retinal I/R injury. In this study, we aimed to investigate the roles of chemokine receptor CXCR5 in the pathological process of retinal I/R injury model.

Method

Retinal I/R injury model was established in CXCR5 knockout and wild mice by the acute elevation of intraocular pressure (AOH) for 60 minutes, and the eyes were harvested for further analyses. The cellular location of CXCR5 was detected by immunofluorescence staining; the expressions of CXCR5 and CXCL13 after I/R injury were analyzed by quantitative RT-PCR. The retinal microglia were detected as stained for Iba1 (+). Leakage of inflammatory cells was observed on the H&E stained cryosections. The protein expression and quantification of zonula occludens (ZO-1) were determined by Western blotting and densitometry. Capillary degeneration was identified on the intact retinal vasculatures prepared by trypsin digestion.

Results

The number of activated microglia marked by Iba1 antibody in the retina was increased after retinal I/R injury in both KO and WT mice, more significant in KO mice. The leakage of inflammatory cells was observed largely at 2 days after injury, but there was no or little leakage at 7 days. The number of inflammatory cells (mainly neutrophils) was greater in CXCR5 KO mice than in WT mice, mainly located under internal limiting membrane. CXCR5 deficiency led to more ZO-1 degradation in CXCR5 KO mice compared to C57BL6 WT mice 2 days after reperfusion. The cellular capillaries were also significantly increased in the KO mice compared to the WT mice.

Conclusion

Our findings suggest that the chemokine receptor CXCR5 may protect retina from ischemia-reperfusion injury by its anti-inflammatory effects. Thus, CXCR5 may be a promising therapeutic target for the treatment of retinal I/R injury.

Nutraceuticals for the Treatment of Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most common complications of diabetes mellitus and is characterized by degeneration of retinal neurons and neoangiogenesis, causing a severe threat to vision. Nowadays, the principal treatment options for DR are laser photocoagulation, vitreoretinal surgery, or intravitreal injection of drugs targeting vascular endothelial growth factor. However, these treatments only act at advanced stages of DR, have short term efficacy, and cause side effects. Treatment with nutraceuticals (foods providing medical or health benefits) at early stages of DR may represent a reasonable alternative to act upstream of the disease, preventing its progression. In particular, in vitro and in vivo studies have revealed that a variety of nutraceuticals have significant antioxidant and anti-inflammatory properties that may inhibit the early diabetes-driven molecular mechanisms that induce DR, reducing both the neural and vascular damage typical of DR. Although most studies are limited to animal models and there is the problem of low bioavailability for many nutraceuticals, the use of these compounds may represent a natural alternative method to standard DR treatments.

Chronic consumption of the dietary polyphenol chrysin attenuates metabolic disease in fructose-fed rats

PURPOSE

Metabolic syndrome (MS) is a major public health issue worldwide and fructose consumption has been associated with MS development. Recently, we showed that the dietary polyphenol chrysin is an effective inhibitor of fructose uptake by human intestinal epithelial cells. Therefore, our aim was to investigate if chrysin interferes with the development of MS induced by fructose in an animal model.

METHODS

Adult male Sprague-Dawley rats (220-310 g) were randomly divided into four groups: (A) tap water (control), (B) tap water and a daily dose of chrysin (100 mg/kg) by oral administration (chrysin) (C) 10% fructose in tap water (fructose), and (D) 10% fructose in tap water and a daily dose of chrysin (100 mg/kg) by oral administration (fructose + chrysin). All groups were fed ad libitum with standard laboratory chow diet and dietary manipulation lasted 18 weeks.

RESULTS

Fructose-feeding for 18 weeks induced an increase in serum triacylglycerols, insulin and angiotensin II levels and in hepatic fibrosis and these changes did not occur in fructose + chrysin rats. Moreover, the increase in both systolic and diastolic blood pressure which was found in fructose-fed animals from week 14th onwards was not observed in fructose + chrysin animals. In contrast, the increase in energy consumption, liver/body, heart/body and right kidney/body weight ratios, serum proteins, serum leptin and liver triacylglycerols observed in fructose-fed rats was not affected by chrysin.

CONCLUSIONS

Chrysin was able to protect against some of the MS features induced by fructose-feeding.

Chrysin Ameliorates Malfunction of Retinoid Visual Cycle through Blocking Activation of AGE-RAGE-ER Stress in Glucose-Stimulated Retinal Pigment Epithelial Cells and Diabetic Eyes

Diabetes-associated visual cycle impairment has been implicated in diabetic retinopathy, and chronic hyperglycemia causes detrimental effects on visual function. Chrysin, a naturally occurring flavonoid found in various herbs, has anti-inflammatory, antioxidant, and neuroprotective properties. The goal of the current study was to identify the retinoprotective role of chrysin in maintaining robust retinoid visual cycle-related components. The in vitro study employed human retinal pigment epithelial (RPE) cells exposed to 33 mM of glucose or advanced glycation end products (AGEs) in the presence of 1–20 μM chrysin for three days. In the in vivo study, 10 mg/kg of chrysin was orally administrated to db/db mice. Treating chrysin reversed the glucose-induced production of vascular endothelial growth factor, insulin-like growth factor-1, and pigment epithelium-derived factor (PEDF) in RPE cells. The outer nuclear layer thickness of chrysin-exposed retina was enhanced. The oral gavage of chrysin augmented the levels of the visual cycle enzymes of RPE65, lecithin retinol acyltransferase (LRAT), retinol dehydrogenase 5 (RDH5), and rhodopsin diminished in db/db mouse retina. The diabetic tissue levels of the retinoid binding proteins and the receptor of the cellular retinol-binding protein, cellular retinaldehyde-binding protein-1, interphotoreceptor retinoid-binding protein and stimulated by retinoic acid 6 were restored to those of normal mouse retina. The presence of chrysin demoted AGE secretion and AGE receptor (RAGE) induction in glucose-exposed RPE cells and diabetic eyes. Chrysin inhibited the reduction of PEDF, RPE 65, LRAT, and RDH5 in 100 μg/mL of AGE-bovine serum albumin-exposed RPE cells. The treatment of RPE cells with chrysin reduced the activation of endoplasmic reticulum (ER) stress. Chrysin inhibited the impairment of the retinoid visual cycle through blocking ER stress via the AGE-RAGE activation in glucose-stimulated RPE cells and diabetic eyes. This is the first study demonstrating the protective effects of chrysin on the diabetes-associated malfunctioned visual cycle.

Chrysin Inhibits Advanced Glycation End Products-Induced Kidney Fibrosis in Renal Mesangial Cells and Diabetic Kidneys

Advanced glycation end products (AGEs) play a causative role in the development of diabetic nephropathy via induction of matrix protein deposition in kidneys. This study investigated inhibitory effects of chrysin, present in bee propolis and herbs, on glomerulosclerosis in db/db mice and AGEs-exposed renal mesangial cells. The in vivo study explored the demoting effects of 10 mg/kg chrysin on glomerular fibrosis in a type 2 diabetic model. Oral supplementation of chrysin inhibited the collagen fiber accumulation and &alpha;-smooth muscle actin (&alpha;-SMA) induction in periodic acid schiff-positive renal tissues of db/db mice. Moreover, treating db/db mice with chrysin diminished the level of AGEs increased in diabetic glomeruli. The in vitro study employed human mesangial cells exposed to 100 &mu;g/mL AGE-BSA for 72 h in the presence of 1⁻20 &mu;M chrysin. Glucose increased mesangial AGE production via induction of receptor for AGEs. Chrysin suppressed the induction of collagens, &alpha;-SMA, fibroblast-specific protein-1 and matrix metalloproteinases enhanced by AGE-bovine serum albumin. Furthermore, chrysin blunted transforming growth factor-&beta;1 induction and Smad 2/3 activation in AGEs-exposed mesangial cells. These results demonstrate that chrysin attenuated accumulation of myofibroblast-like cells and matrix proteins in AGEs-laden diabetic glomeruli. Therefore, chrysin may be a potential renoprotective agent targeting glucose-mediated AGEs-associated glomerulosclerosis and fibrosis.

Effects of Crocin on Diabetic Maculopathy: A Placebo-Controlled Randomized Clinical Trial

OBJECTIVE

Diabetic macular edema (DME) is one of the most important sight-threatening complications in patients with diabetes. Owing to neuroprotective properties, crocin, as the main constituent in saffron, is thought to be useful in the treatment and prevention of diabetic maculopathy. The aim of this trial was to evaluate the effects of crocin as a supplement on reducing inflammation in patients with diabetic maculopathy.

DESIGN

Double-masked, placebo controlled, phase 2 randomized clinical trial.

METHODS

Participants: In this study, 101 eyes of 60 patients with refractory diabetic maculopathy to conventional therapy including macular photocoagulation and intravitreal injection of anti-vascular endothelial growth factor agent (bevacizumab) with or without steroid (triamcinolone) were studied in 3 groups.

INTERVENTION

Patients in the crocin groups received 5 mg or 15 mg crocin tablets per day for 3 months, whereas patients in the placebo group received 1 placebo tablet per day during the study. The best-corrected visual acuity (BCVA) and central macular thickness (CMT) were measured before, every month during, and 3 months after intervention. Biochemical blood tests were also evaluated before and after trial.

MAIN OUTCOME MEASURES

The BCVA and CMT were evaluated as the primary outcomes, whereas HbA1c and fasting blood sugar (FBS) were studied as the secondary outcomes in this trial.

RESULTS

One hundred and one eyes were enrolled in this trial and were divided into 3 groups (crocin 5 mg, n = 34; crocin 15 mg, n = 33; and placebo, n = 34). According to our data, administration of crocin 15 mg tablet per day could significantly decrease HbA1c (P value = .024; 95% confidence interval [CI] 0.3-0.96), and CMT (P value = .005; 95% CI, 32.75-126.99) and improve BCVA (logMAR changes; P value = .012; 95% CI, 0.23-0.69) compared to the placebo group. Although administration of crocin 5 mg tablet per day could clinically improve HbA1c, FBS, CMT, and BCVA, the difference was not significant compared to the placebo group.

CONCLUSION

This study indicated the effect of crocin as a potent antioxidant and neuroprotective for treatment of refractory DME in the short term; however, the clinical significance is yet to be proved in a study with larger sample size and longer duration of follow-up and also in treatment-naïve patients.