Natural antioxidants in diabetes treatment and management: prospects of astaxanthin

Targeting diabetes with flavonoids from Indonesian medicinal plants: a review on mechanisms and drug discovery

The rich biodiversity of Indonesia provides a wide variety of plants rich in flavonoids, which show promising potential as antidiabetic agents. Flavonoids are polyphenolic compounds recognized for their broad biological activities, such as antioxidant, anti-inflammatory, and antidiabetic effects. Traditional Indonesian medicinal plants such as Syzygium cumini, Moringa oleifera, and Curcuma longa are currently being studied for their flavonoid content and potential in diabetes treatment. Studies suggest that flavonoids can influence crucial pathways in diabetes management, including enhancing insulin sensitivity, boosting insulin production, and safeguarding pancreatic β cells against damage caused by oxidative stress. For example, quercetin and kaempferol, flavonoids in many Indonesian plants, have demonstrated potential for managing glucose metabolism and lowering high blood sugar levels. Additionally, these substances have been shown to inhibit enzymes such as α-glucosidase and α-amylase, which are involved in the breakdown of carbohydrates, thus aiding in the regulation of blood sugar levels after meals. The antioxidant qualities of flavonoids play a crucial role in fighting oxidative stress and are a significant contributor to the development of diabetes and related complications. Flavonoids help neutralize free radicals and enhance the body's antioxidant protection, reducing oxidative harm and promoting metabolic wellness. Additionally, their anti-inflammatory properties aid in reducing the chronic inflammation linked to insulin resistance and β-cell dysfunction. Formulation advancements, such as nanocarrier technology, have been explored to boost the effectiveness of flavonoid-based therapies. Due to its vast plant diversity, Indonesia offers a potential reservoir for new antidiabetic drugs, meriting additional research and development with the aim of this review providing new knowledge on the potential of flavonoids that can play a role in the treatment of diabetes.

Metabolic and Mitochondrial Dysregulations in Diabetic Cardiac Complications

The growing prevalence of diabetes highlights the urgent need to study diabetic cardiovascular complications, specifically diabetic cardiomyopathy, which is a diabetes-induced myocardial dysfunction independent of hypertension or coronary artery disease. This review examines the role of mitochondrial dysfunction in promoting diabetic cardiac dysfunction and highlights metabolic mechanisms such as hyperglycaemia-induced oxidative stress. Chronic hyperglycaemia and insulin resistance can activate harmful pathways, including advanced glycation end-products (AGEs), protein kinase C (PKC) and hexosamine signalling, uncontrolled reactive oxygen species (ROS) production and mishandling of Ca2+ transient. These processes lead to cardiomyocyte apoptosis, fibrosis and contractile dysfunction. Moreover, endoplasmic reticulum (ER) stress and dysregulated RNA-binding proteins (RBPs) and extracellular vesicles (EVs) contribute to tissue damage, which drives cardiac function towards heart failure (HF). Advanced patient-derived induced pluripotent stem cell (iPSC) cardiac organoids (iPS-COs) are transformative tools for modelling diabetic cardiomyopathy and capturing human disease's genetic, epigenetic and metabolic hallmarks. iPS-COs may facilitate the precise examination of molecular pathways and therapeutic interventions. Future research directions encourage the integration of advanced models with mechanistic techniques to promote novel therapeutic strategies.

Effects of dietary oxidative balance score on diabetic nephropathy and renal function: insights from retrospective and cross-sectional studies

Background

The relationship between dietary oxidative balance score (DOBS) and diabetes-related renal events remains unclear.

Methods

In this study, the associations between serum micronutrients and diabetic nephropathy (DN) in participants matched by propensity score (PSM) were retrospectively analyzed. And next, a cross-sectional analysis was performed with the National Health and Nutritional Examination Survey (NHANES) database. Weighted multivariate adjusted logistic regression models, dose-response curves, subgroup analysis, and mediation analysis were the main methods of this study. Finally, sensitivity analyses were performed by PSM and multiple imputation (MI).

Results

Retrospective findings suggest that single antioxidants may not be representative of an individual's overall antioxidant levels. The results of the cross-sectional study indicated that the higher the DOBS, the greater the beneficial effects on DN [Q4 vs. Q1: OR (95% CI): 0.78 (0.63, 0.96), p for trend = 0.008] and renal function in DN [Q4 vs. Q1: β (95% CI): 5.395 (1.590, 9.199), p for trend = 0.004]. The above correlations were linear negative correlation (p for nonlinear = 0.989) and linear positive correlation (p for nonlinear = 0.593) respectively. Chronic inflammation mediated the above associations to some extent. The results of sensitivity analysis were consistent with the original analysis.

Conclusion

Higher dietary antioxidant exposure has a positive effect on DN and renal function in DN, mediated partially by chronic inflammation.

Therapeutic potential of microalgae-derived natural compounds in diabetic wound healing: A comprehensive review

A variety of cell types and chemical systems are known to interact throughout the complex process of wound healing. In addition to being very uncomfortable for patients, wounds that do not heal properly or become chronic can place a heavy burden on society. The creation of novel treatment approaches can expedite the healing process, reduce the societal burden, and improve patient outcomes. Due to advancements in the field of biomedical science, microalgae have significant potential for use in diabetic wound healing and other wound healing applications. This review delves into the physiological process of wound healing, the use of microalgae in wound healing, and a detailed explanation of the wound healing roles of various microalgal originated bioactive compounds including alginate, pigments, fatty acids, proteins, polysaccharides, flavonoids and phenols. The study discusses the efficacy of photosynthetic hydrogels in drugs and oxygen delivery to the wounded area that is crucial for promoting a good healing process, as well as highlights the drawbacks and challenges involved in using microalgae for wound healing. Given the current state of the art in utilizing microalgae for wound care, this review provides new perspectives for further research, along with insightful advice and innovative suggestions for academics engaged in this area.

Structural Characterization of Polysaccharides from Noni (Morinda citrifolia L.) Juice and Their Preventive Effect on Oxidative Stress Activity

Polysaccharides are very promising molecules in the field of pharmacotherapy. Knowing this, the aim of this study was to extract, characterize, and evaluate the action of the polysaccharides in noni juice, using biological models of Type 2 diabetes mellitus processes. In this study, one polysaccharide named NJSPd-1 was separated from fermented noni fruit juice. The characterization assay showed that NJSPd-1 had a molecular weight (Mw) of 18,545 Da. NJSPd-1 consisted of galacturonic acid, galactose, rhamnose, and arabinose, with a molar ratio of 28.79:20.34:19.80:18.84 according to HPGPC analysis, and the glycosidic bond mainly included →4)-α-D-GalAp-(1→, 4)-β-D-Glcp-(1→, →2)-α-L-Rhap-(1→, and →3)-α-L-Araf-(1→. The prevention of oxidative stress activities by NJSPd-1 was evaluated using high-glucose-induced oxidative stress in HepG2 cells. In vitro results showed that NJSPd-1 influenced the downregulation of the proteins and genes Nrf2, Keap1, HO-1, and NQO1 in HepG2 cells. These results suggest that NJSPd-1 exerted a protective effect against oxidative stress in HepG2 cells by activating the Nrf2/HO-1/NQO1 signaling pathway.

Diabetes and the associated complications: The role of antioxidants in diabetes therapy and care

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by high blood sugar levels (hyperglycemia). Poorly managed diabetes can lead to complications affecting multiple organ systems. Antioxidants play a crucial role in reducing oxidative stress caused by reactive oxygen species (ROS), primarily triggered by uncontrolled high blood sugar levels in diabetes. Antioxidants like vitamin C, E, selenium, and alpha-lipoic acid, when used as supplements, have shown promise in reducing oxidative stress markers and improving antioxidant status in laboratory and animal studies and diabetic patients. Antioxidant supplementation may help reduce the risk of diabetic complications such as neuropathy, nephropathy, retinopathy, and cardiovascular disease. Additionally, antioxidants also have anti-inflammatory properties, which could be beneficial in reducing inflammation associated with diabetes. Antioxidant supplementation has been shown to enhance endothelial function, insulin sensitivity, and glucose metabolism, thereby aiding in glycemic control and overall diabetic management. Combining antioxidants with certain medications may have therapeutic benefits, such as effectively neutralizing free radicals and enhancing the regulation of antioxidant defense systems. This review presents an update on diabetes, the sources of free radical generation, the body's natural defense mechanisms, the clinical evidence regarding using antioxidants in managing diabetic complications, and the potential new therapeutic approaches. Overall, antioxidant supplementation may offer some benefits in managing diabetic complications. However, further studies are needed to understand the mechanisms of action, determine the optimal supplementation, explore potential interactions with other medications, and conduct long-term studies to establish the possible use of antioxidants for optimal benefits in diabetes care.

Preparation and characterization of ovomucin self-assembly nanoparticles under glycerol compression for astaxanthin delivery: Sustained release and antioxidant activity

Astaxanthin (AST) is a natural hydrophobic nutrient with various biological activities, but its low solubility limits its application. In this study, self-assembly nanoparticles were prepared by ovomucin (OVM) and Ca2+ with the enhancement of glycerol to deliver AST. Glycerol compressed the particle size of nanoparticles from 175.7 ± 1.8 to 142.9 ± 0.6 nm, and the nanoparticles had a strong negative charge (-28.9 ± 0.6 mV). Ultraviolet-visible spectroscopy and X-ray diffraction (XRD) confirmed the successful encapsulation of AST in an amorphous form with a high encapsulation efficiency (82.9% ± 2.1%). Fourier transform infrared and circular dichroism analyses demonstrated that nanoparticles formation mainly involved electrostatic interactions and hydrophobic interactions. AST in nanoparticles presented excellent gastric juice resistance and sustained release ability, whereas free radical scavenging efficiency reached up to 75%. In addition, the nanoparticles had no apparent toxicity to cell viability. This study is expected to provide a new insight into the safe and efficient delivery of AST, while demonstrating the potential of OVM as a delivery carrier in the food and health industries.

N6-methyladenosine demethylase fat mass and obesity-associated protein suppresses hyperglycemia-induced endothelial cell injury by inhibiting reactive oxygen species formation via autophagy promotion

INTRODUCTION

Hyperglycemia-induced endothelial cell injury is one of the main causes of diabetic vasculopathy. Fat mass and obesity-associated protein (FTO) was the first RNA N6-methyladenosine (m6A) demethylase identified; it participates in the pathogenesis of diabetes. However, the role of FTO in hyperglycemia-induced vascular endothelial cell injury remains unclear.

MATERIALS AND METHODS

The effects of FTO on cellular m6A, autophagy, oxidative stress, proliferation, and cytotoxicity were explored in human umbilical vein endothelial cells (HUVECs) treated with high glucose (33.3 mmol/mL) after overexpression or pharmacological inhibition of FTO. MeRIP-qPCR and RNA stability assays were used to explore the molecular mechanisms by which FTO regulates autophagy.

RESULTS

High glucose treatment increased m6A levels and reduced FTO protein expression in HUVECs. Wild-type overexpression of FTO markedly inhibited reactive oxygen species generation by promoting autophagy, increasing endothelial cell proliferation, and decreasing the cytotoxicity of high glucose concentrations. The pharmacological inhibition of FTO showed the opposite results. Mechanistically, we identified Unc-51-like kinase 1 (ULK1), a gene responsible for autophagosome formation, as a downstream target of FTO-mediated m6A modification. FTO overexpression demethylated ULK1 mRNA and inhibited its degradation in an m6A-YTHDF2-dependent manner, leading to autophagy activation.

CONCLUSIONS

Our study demonstrates the functional importance of FTO-mediated m6A modification in alleviating endothelial cell injury under high glucose conditions and indicates that FTO may be a novel therapeutic target for diabetic vascular complications.

Advances in the treatment of type 2 diabetes mellitus by natural plant polysaccharides through regulation of gut microbiota and metabolism: A review

The prevalence and impact of type 2 diabetes mellitus (T2DM) is a major global health problem. The treatment process of T2DM is long and difficult to cure. Therefore, it is necessary to explore alternative or complementary methods to deal with the various challenges brought by T2DM. Natural plant polysaccharides (NPPs) have certain potential in the treatment of T2DM. However, many studies have not considered the relationship between the structure of NPPs and their anti-T2DM activity. This paper reviews the relevant anti-T2DM mechanisms of NPPs, including modulation of insulin action, promotion of glucose metabolism and modulation of postprandial glucose levels, anti-inflammation and modulation of gut microbiota (GM) and metabolism. This paper provides an in-depth study of the conformational relationships of NPPs and facilitates the development of anti-T2DM drugs or dietary supplements with NPPs.

Biovalorisation of agro-industrial wastes into astaxanthin by Xanthophyllomyces dendrorhous

Astaxanthin is a red xanthophyll with high economic and industrial value in the pharmaceutical, nutraceutical, cosmetic and food industries. In recent years, the biotechnological production of astaxanthin has attracted much attention as a sustainable alternative to the predominating petrochemical-dependent chemical synthesis. In this regard, Xanthophyllomyces dendrorhous is regarded as a promising microorganism for industrial production of astaxanthin. Unfortunately, biotechnological production of the carotenoid is currently expensive. The present study investigated soy molasses (SM) and residual brewers' yeast as cheap fermentation feedstocks for the cultivation of X. dendrorhous and astaxanthin production. Yeast extract was obtained from residual brewers' yeast using various techniques and then combined with SM to formulate a two-component growth medium which was subsequently used to cultivate X. dendrorhous. Generally, the yeast extract produced from residual brewers' yeast supported X. dendrorhous growth and astaxanthin production at levels comparable to those seen with commercial yeast extract. Overall, cultivating X. dendrorhous in an SM-based medium containing 5% SM and 0.2% yeast extract obtained from residual brewers' yeast resulted in significantly higher (> 20% more) biomass accumulation compared to the control media (YPD). A similar slightly higher astaxanthin output (up to 14% more) was recorded in the SM-based medium compared to YPD. The formulated cultivation medium in this study provides an opportunity to reduce the production cost of astaxanthin from X. dendrorhous while simultaneously reducing the environmental impact related to the disposal of the industrial waste used as feedstock. KEY POINTS: • Cheap culture media were formulated from soy molasses and brewers' spent yeast • The formulated medium resulted in at least 20% more biomass than the control • Up to 14% more astaxanthin was produced in molasses-based medium.

Multifunctional Nanotherapeutics with Long-Acting Release against Macular Degeneration by Minimally Invasive Administration

Neovascular age-related macular degeneration (AMD), a leading cause of blindness, requires frequent intravitreal injection of antivascular endothelial growth factor (anti-VEGF), which could generate a succession of complications with poor patient compliance. The current VEGF-targeting therapies often fail in half of patients due to the complex pathologic microenvironment of excessive reactive oxygen species (ROS) production, and increased levels of inflammation are accompanied by choroidal neovascularization (CNV). We herein reported multifunctional nanotherapeutics featuring superior antioxidant and anti-inflammation properties that aim to reverse the pathological condition, alongside its strong targeted antiangiogenesis to CNV and its ability to provide long-term sustained bioactive delivery via the minimally invasive subconjunctival injection, so as to achieve satisfactory wet AMD treatment effects. Concretely, the nanomedicine was designed by coencapsulation of astaxanthin (AST), a red pigmented carotenoid known for its antioxidative, anti-inflammatory and antiapoptotic properties, and axitinib (AXI), a small molecule tyrosine kinase inhibitor that selectively targets the vascular epidermal growth factor receptor for antiangiogenesis, into the Food and Drug Administration (FDA) approved poly(lactic-co-glycolic acid) (PLGA), which forms the nanodrug of PLGA@AST/AXI. Our results demonstrated that a single-dose subconjunctival administration of PLGA@AST/AXI showed a rational synergistic effect by targeting various prevailing risk factors associated with wet AMD, ensuring persistent drug release profiles, maintaining good ocular biocompatibility, and causing no obvious mechanical damage. Such attributes are vital and hold significant potential in treating ocular posterior segment diseases. Moreover, this nanotherapeutic strategy represents a versatile and broad-spectrum nanoplatform, offering a promising alternative for the complex pathological progression of other neovascular diseases.

Effect of High-Sucrose Diet on the Occurrence and Progression of Diabetic Retinopathy and Dietary Modification Strategies

As the most serious of the many worse new pathological changes caused by diabetes, there are many risk factors for the occurrence and development of diabetic retinopathy (DR). They mainly include hyperglycemia, hypertension, hyperlipidemia and so on. Among them, hyperglycemia is the most critical cause, and plays a vital role in the pathological changes of DR. High-sucrose diets (HSDs) lead to elevated blood glucose levels in vivo, which, through oxidative stress, inflammation, the production of advanced glycation end products (AGEs) and vascular endothelial growth factor (VEGF), cause plenty of pathological damages to the retina and ultimately bring about loss of vision. The existing therapies for DR primarily target the terminal stage of the disease, when irreversible visual impairment has appeared. Therefore, early prevention is particularly critical. The early prevention of DR-related vision loss requires adjustments to dietary habits, mainly by reducing sugar intake. This article primarily discusses the risk factors, pathophysiological processes and molecular mechanisms associated with the development of DR caused by HSDs. It aims to raise awareness of the crucial role of diet in the occurrence and progression of DR, promote timely changes in dietary habits, prevent vision loss and improve the quality of life. The aim is to make people aware of the importance of diet in the occurrence and progression of DR. According to the dietary modification strategies that we give, patients can change their poor eating habits in a timely manner to avoid theoretically avoidable retinopathy and obtain an excellent prognosis.

Modulatory Properties of Vitamin D in Type 2 Diabetic Patients: A Focus on Inflammation and Dyslipidemia

BACKGROUND

Evidence from preclinical studies has found a correlation between the development of type 2 diabetes (T2D) and vitamin D deficiency. However, evidence from randomized controlled trials (RCTs) revealed inconclusive results on vitamin D supplementation. We explored the effect of vitamin D on inflammation and dyslipidemia in T2D.

METHODS

We comprehensively searched for RCTs evaluating the effect of vitamin D in T2D on PubMed. Data were analyzed using Review Manager 5.3 and reports, such as standardized mean difference (SMD) and 95% confidence intervals (CI) at a 5% significant level using a random effect model.

RESULTS

This study revealed a significant reduction in tumor necrosis factor-alpha (TNF-α) SMD = (-0.51, 95%CI (-0.93, -0.09); p = 0.02), high sensitivity C-reactive protein (hs-CRP) SMD = (-1.06, 95%CI (-1.67, -0.45); p < 0.05) in vitamin D compared to placebo. Additionally, interleukin-6 (IL-6) exhibited a marginal effect SMD = (-0.52, 95%CI (-1.05, 0.01), p = 0.05). Furthermore, a significant reduction in the level of triglycerides SMD = (-0.65, 95%CI (-1.11, -0.18), p < 0.05) was observed, concomitant to a significantly increased high-density lipoprotein (HDL) level SMD = (0.53, 95%CI (0.08, 0.98), p = 0.02). However, no statistically significant changes were observed in total cholesterols SMD = (-0.16, 95%CI (-0.57, 0.24), p = 0.43) and low-density lipoprotein (LDL) SMD = (-0.06, 95%CI (-0.37, 0.24), p = 0.67).

CONCLUSIONS

These findings suggest that vitamin D supplementation may be beneficial in ameliorating inflammation and dyslipidemia in T2D patients.

A Narrative Review: The Effect and Importance of Carotenoids on Aging and Aging-Related Diseases

Aging is generally defined as a time-dependent functional decline that affects most living organisms. The positive increase in life expectancy has brought along aging-related diseases. Oxidative stress caused by the imbalance between pro-oxidants and antioxidants can be given as one of the causes of aging. At the same time, the increase in oxidative stress and reactive oxygen species (ROS) is main reason for the increase in aging-related diseases such as cardiovascular, neurodegenerative, liver, skin, and eye diseases and diabetes. Carotenoids, a natural compound, can be used to change the course of aging and aging-related diseases, thanks to their highly effective oxygen-quenching and ROS-scavenging properties. Therefore, in this narrative review, conducted using the PubMed, ScienceDirect, and Google Scholar databases and complying with the Scale for the Assessment of Narrative Review Articles (SANRA) guidelines, the effects of carotenoids on aging and aging-related diseases were analyzed. Carotenoids are fat-soluble, highly unsaturated pigments that occur naturally in plants, fungi, algae, and photosynthetic bacteria. A large number of works have been conducted on carotenoids in relation to aging and aging-related diseases. Animal and human studies have found that carotenoids can significantly reduce obesity and fatty liver, lower blood sugar, and improve liver fibrosis in cirrhosis, as well as reduce the risk of cardiovascular disease and erythema formation, while also lowering glycated hemoglobin and fasting plasma glucose levels. Carotenoid supplementation may be effective in preventing and delaying aging and aging-related diseases, preventing and treating eye fatigue and dry eye disease, and improving macular function. These pigments can be used to stop, delay, or treat aging-related diseases due to their powerful antioxidant, restorative, anti-proliferative, anti-inflammatory, and anti-aging properties. As an increasingly aging population emerges globally, this review could provide an important prospective contribution to public health.

In vitro and in vivo antioxidant and antihyperglycemic potentials of phenolic fractions of Syzygium zeylanicum (L.) DC trunk-bark

Syzygium zeylanicum L. (DC) (SZL) has been used in antidiabetes treatment for ages. However, the scientific evidence of active agents that have antidiabetic activity and response against biological activities is limited. In this study, the active components of SZL trunk-bark extract (SZL extract) were identified using principal component analysis (PCA), and their antidiabetic activities were assessed. The results indicated that the ethyl acetate fraction (EAF) had the highest concentration of phenolic compounds, antioxidants, and antihyperglycemic activities in the postprandial zebrafish model. The major antioxidant contributors were gallic acid, catechin, epicatechin, ellagic acid, quercetin, caffeine, and apigenin, and their concentrated levels reduced α-amylase inhibitory activity, whereas rutin and ethyl gallate influenced the α-glucosidase inhibitory activity. This study showed the bio-functional properties of active phenolic compounds present in the SZL extract, potentially serving as a functional food to control hyperglycemia.

Evaluation of Antidiabetic Effect of Combined Leaf and Seed Extracts of Moringa oleifera (Moringaceae) on Alloxan-Induced Diabetes in Mice: A Biochemical and Histological Study

Moringa oleifera (Moringaceae) is a medicinal plant rich in biologically active compounds. The aim of the present study was to screen M. oleifera methanolic leaf (L) extract, seed (S) extract, and a combined leaf/seed extract (2L : 1S ratio) for antidiabetic and antioxidant activities in mice following administration at a dose level of 500 mg/kg of body weight/day. Diabetes was induced by alloxan administration. Mice were treated with the extracts for 1 and 3 months and compared with the appropriate control. At the end of the study period, the mice were euthanized and pancreas, liver, kidney, and blood samples were collected for the analysis of biochemical parameters and histopathology. The oral administration of the combined L/S extract significantly reduced fasting blood glucose to normal levels compared with L or S extracts individually; moreover, a significant decrease in cholesterol, triglycerides, creatinine, liver enzymes, and oxidant markers was observed, with a concomitant increase in antioxidant biomarkers. Thus, the combined extract has stronger antihyperlipidemic and antioxidant properties than the individual extracts. The histopathological results also support the biochemical parameters, showing recovery of the pancreas, liver, and kidney tissue. The effects of the combined L/S extracts persisted throughout the study period tested. To the best of our knowledge, this is the first study to report on the antidiabetic, antioxidant, and antihyperlipidemic effects of a combined L/S extract of M. oleifera in an alloxan-induced diabetic model in mice. Our results suggest the potential for developing a natural potent antidiabetic drug from M. oleifera; however, clinical studies are required.

The ameliorative effect of zinc acetate with caffeic acid in the animal model of type 2 diabetes

Recently the complexation-mediated antioxidative and glycaemic control synergism between zinc(II) and caffeic acid was demonstrated in vitro. The present study evaluated the complexation-mediated antidiabetic and antioxidative synergism between zinc(II) and caffeic acid in diabetic rats and the possible underlying mechanisms. Male SD rats were induced with diabetes using 10% fructose and 40 mg/kg bw streptozotocin. The diabetic rats were treated with Zn(II)-caffeic acid complex and its precursors (caffeic acid and zinc acetate) for 4 weeks at predetermined doses. The effect of the treatments on diabetes and oxidative stress was measured. The complex ameliorated diabetic alterations. It reduced polyphagia and polydipsia and recovered weight loss. It increased insulin secretion, insulin sensitivity, hepatic and muscle glycogen, muscle hexokinase activity and Akt phosphorylation, which resulted in improved glucose tolerance and reduced blood glucose in the diabetic rats. The complex concomitantly reduced systemic and tissue lipid peroxidation and increased antioxidant enzymes activity in the diabetic rats. The complex outperformed the antidiabetic and antioxidative action of its precursors and had a broader bioactivity profile. Complexing zinc acetate with caffeic acid improved their ameliorative effect on insulin resistance by ∼24% and 42%, respectively, as well as their anti-hyperglycaemic action by ∼24 - 36% and ∼42 - 47%, respectively, suggesting a complexation-mediated synergism. In some instances, the antidiabetic action of the complex was comparable to metformin, while its antioxidant effect was better than that of metformin. Zinc(II)-caffeic acid complexation may be an alternative approach to improving the efficacy of antidiabetic and antioxidative therapy with minimal adverse or side effects.

Metabolic mechanism of astaxanthin biosynthesis in Xanthophyllomyces dendrorhous in response to sodium citrate treatment

Astaxanthin is an important ketocarotenoid widely used in industries. However, its application is limited because of its low yield. Sodium citrate (Na-citrate), one of the major carbon sources for microorganisms, can promote cell growth and product accumulation. The basidiomycetous red yeast Xanthophyllomyces dendrorhous was thus used to study the effect of Na-citrate on cell growth and astaxanthin synthesis. The highest biomass and astaxanthin yield (6.0 g/L and 22.5 mg/L) were obtained in shake-flask when 3 g/L Na-citrate was added at 24 h and were 1.8 and 2.0 times higher than those of the control group, respectively. Furthermore, metabolomics and real-time reverse transcription PCR (qRT-PCR) analysis were conducted to study the metabolic pathways of X. dendrorhous in response to Na-citrate. The qRT-PCR assay revealed that Na-citrate facilitated glucose consumption, promoted the metabolic flux from glycolysis, and regulated the tricarboxylic acid (TCA) cycle, providing more energy and substrates for the synthesis of astaxanthin. The gene analysis revealed that adding Na-citrate significantly upregulated the expression of six key genes (ICL, HMGS, crtE, crtYB, crtI, and crtS) involved in pathways related to astaxanthin biosynthesis. These results suggest that exogenous Na-citrate treatment is a potentially valuable strategy to stimulate astaxanthin production in X. dendrorhous.

Antidiabetic Properties of Plant Secondary Metabolites

The prevalence of diabetes mellitus is one of the major medical problems that the modern world is currently facing. Type 1 and Type 2 diabetes mellitus both result in early disability and death, as well as serious social and financial problems. In some cases, synthetic drugs can be quite effective in the treatment of diabetes, though they have side effects. Plant-derived pharmacological substances are of particular interest. This review aims to study the antidiabetic properties of secondary plant metabolites. Existing review and research articles on the investigation of the antidiabetic properties of secondary plant metabolites, the methods of their isolation, and their use in diabetes mellitus, as well as separate articles that confirm the relevance of the topic and expand the understanding of the properties and mechanisms of action of plant metabolites, were analyzed for this review. The structure and properties of plants used for the treatment of diabetes mellitus, including plant antioxidants, polysaccharides, alkaloids, and insulin-like plant substances, as well as their antidiabetic properties and mechanisms for lowering blood sugar, are presented. The main advantages and disadvantages of using phytocomponents to treat diabetes are outlined. The types of complications of diabetes mellitus and the effects of medicinal plants and their phytocomponents on them are described. The effects of phytopreparations used to treat diabetes mellitus on the human gut microbiota are discussed. Plants with a general tonic effect, plants containing insulin-like substances, plants-purifiers, and plants rich in vitamins, organic acids, etc. have been shown to play an important role in the treatment of type 2 diabetes mellitus and the prevention of its complications.

The Effect of Vitamin D on Inflammation and Dyslipidemia in Type 2 Diabetes Mellitus: Protocol for a Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Type 2 diabetes mellitus is a chronic disease that contributes to an increasing global burden on the health system. It has a high chance of leading to macrovascular complications and cardiovascular disease. As an inflammatory condition, it would be essential to target inflammatory pathways when developing therapeutic drugs for type 2 diabetes mellitus.

OBJECTIVE

We aimed to evaluate the effect of vitamin D on markers of inflammation and lipid profile among adult patients with diabetes.

METHODS

A systematic review will seek studies published on Embase, Google Scholar, PubMed, Web of Science, and Science Direct. This planned systematic review and meta-analysis will be limited to randomized controlled trials; moreover, the search will include published studies regarding the effects of vitamin D on pro-inflammatory cytokines and lipid profiles. The review will include studies published from inception until December 30, 2022. The study identification and selection will be based on the eligibility criteria by 2 independent reviewers. Additionally, a meta-analysis will only be performed if more than 2 studies are available and explore the same outcomes, and this will be analyzed using RevMan (version 5.4.1). The quality and risk of bias will be assessed following the Cochrane risk of bias tool and Jadad checklist.

RESULTS

The process for searching literature review has already started, and this is conducted independently by 2 reviewers using a predefined eligibility and "participants, intervention, comparator, and outcome" criteria. This systematic review and meta-analysis will not require any direct involvement of patients and the public; thus, no ethical approval was required.

CONCLUSIONS

The findings obtained from the proposed study will be presented in scientific seminars, journal clubs, and conferences and published in peer-reviewed journals.

TRIAL REGISTRATION

International Platform of Registered Systematic Review and Meta-analysis Protocols INPLASY202260022; https://inplasy.com/?s=INPLASY202260022.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/42193.

Identification and Quantification of Bioactive Compounds in Organic and Conventional Edible Pansy Flowers (Viola × wittrockiana) and Their Antioxidant Activity

The use of edible flowers has become increasingly popular as a good source of bioactive compounds. Many flowers can be consumed, but there is a lack of information about the chemical composition of organic and conventional flowers. Organic crops represent a higher level of food safety because pesticides and artificial fertilizers are prohibited. The present experiment was carried out with organic and conventional edible pansy flowers of different colors: double-pigmented violet/yellow and single-pigmented yellow flowers. In fresh flowers, the contents of dry matter and polyphenols (including phenolic acids, flavonoids, anthocyanins, carotenoids, and chlorophylls) and the antioxidant activity were determined by the HPLC-DAD method. The results showed that organic edible pansy flowers contained significantly more bioactive compounds, especially polyphenols (333.8 mg/100 g F.W.), phenolic acids (40.1 mg/100 g F.W.), and anthocyanins (293.7 mg/100 g F.W.) compared to conventional methods. Double-pigmented (violet/yellow) pansy flowers are more recommended for the daily diet than single-pigmented yellow flowers. The results are unique and open the first chapter in a book on the nutritional value of organic and conventional edible flowers.

Mitigation of Paeoniae Radix Alba extracts on H2O2-induced oxidative damage in HepG2 cells and hyperglycemia in zebrafish, and identification of phytochemical constituents

Paeoniae Radix Alba (PRA), as a Traditional Chinese Medicine, is widely used in Chinese cuisine due to high health-benefits and nutrition, but the effect of different polarity of solvents on the extraction of antioxidant and hypoglycemic constituents, as well as the major active compounds remain unclear. In this research, 40, 70, and 95% ethanol were firstly applied to extract the polyphenols from PRA, the extraction yields, total phenolics, and total flavonoids content, free radical scavenging ability, α-glucosidase inhibition ability, and anti-glycation ability of extracts were evaluated spectroscopically. The oxidative damage protection, hypoglycemic activity, and alleviation on peripheral nerve damage were evaluated by H₂O₂-induced HepG2 cells and hyperglycemic zebrafish models. UPLC-QTOF-MS/MS was used to identify the major chemical constituents. The results showed that 40, 70, and 95% ethanol exhibited insignificant difference on the extraction of phenolics and flavonoids from PRA. All extracts showed promising DPPH⋅ and ABTS⋅⁺ scavenging ability, α-glucosidase inhibition and anti-glycation ability. In addition, PRA extracts could restore the survival rate of HepG2 cells induced by H₂O₂, and alleviate the oxidative stress by reducing the content of MDA and increasing the levels of SOD, CAT, and GSH-Px. The 70% ethanol extract could also mitigate the blood glucose level and peripheral motor nerve damage of hyperglycemic zebrafish. Thirty-five compounds were identified from 70% ethanol extract, gallotannins, gallic acid and its derivatives, and paeoniflorin and its derivatives were the dominant bioactive compounds. Above results could provide important information for the value-added application of PRA in functional food and medicinal industry.

Nutraceuticals: A Promising Approach Towards Diabetic Neuropathy

BACKGROUND

Various nutraceuticals from different sources have various beneficial actions and have been reported for many years. The important findings from the research conducted using various nutraceuticals exhibiting significant physiological and pharmacological activities have been summarized.

METHODS

An extensive investigation of literature was done using several worldwide electronic scientific databases like PUBMED, SCOPUS, Science Direct, Google Scholar, etc. The entire manuscript is available in the English language that is used for our various compounds of interest. These databases were thoroughly reviewed and summarized.

RESULTS

Nutraceuticals obtained from various sources play a vital role in the management of peripheral neuropathy associated with diabetes. Treatment with nutraceuticals has been beneficial as an alternative in preventing the 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 DPN.

CONCLUSION

Nutraceuticals obtained from different sources like a plant, an animal, and marine have been properly utilized for the safety of health. In our opinion, this review could be of great interest to clinicians, as it offers a complementary perspective on the management of DPN. Trials with a well-defined patient and symptom selection have shown robust pharmacological design as pivotal points to let these promising compounds become better accepted by the medical community.

Therapeutic potential of non-starch polysaccharides on type 2 diabetes: from hypoglycemic mechanism to clinical trials

Non-starch polysaccharides (NSPs) have been reported to exert therapeutic potential on managing type 2 diabetes mellitus (T2DM). Various mechanisms have been proposed; however, several studies have not considered the correlations between the anti-T2DM activity of NSPs and their molecular structure. Moreover, the current understanding of the role of NSPs in T2DM treatment is mainly based on in vitro and in vivo data, and more human clinical trials are required to verify the actual efficacy in treating T2DM. The related anti-T2DM mechanisms of NSPs, including regulating insulin action, promoting glucose metabolism and regulating postprandial blood glucose level, anti-inflammatory and regulating gut microbiota (GM), are reviewed. The structure-function relationships are summarized, and the relationships between NSPs structure and anti-T2DM activity from clinical trials are highlighted. The development of anti-T2DM medication or dietary supplements of NSPs could be promoted with an in-depth understanding of the multiple regulatory effects in the treatment/intervention of T2DM.

Astaxanthin improves preserved semen quality at 17°C by enhancing sperm antioxidant and motility properties

Porcine sperm is rich in polyunsaturated fatty acids; therefore, it is highly susceptible to oxidative damage during storage. Inhibition of oxidative stress during preservation is essential for maintaining sperm motility. Astaxanthin is a potent antioxidant used in the cosmetic and pharmaceutical industries. This study aimed to explore the effect of supplementing astaxanthin as an extender of porcine semen preservation dilutions at 17°C. Various concentrations of astaxanthin were added to diluted porcine semen at 17°C. We performed computer-assisted semen analysis, evaluation of plasma membrane integrity and acrosome integrity, and measurement of total antioxidant activity, malondialdehyde (MDA) content, reactive oxygen species levels, superoxide dismutase (SOD) activity, catalase (CAT) activity, glutathione peroxidase (GSH-PX) activity and sperm motility parameters. Compared with the control group, the addition of 0.25 μg/ml astaxanthin group significantly improved sperm motility parameters stored on the fifth day; these were increased levels of sperm SOD, GSH-PX and CAT (p < .05), increased sperm adenosine trisphosphate and lactate dehydrogenase levels and decreased sperm MDA levels (p < .05). These findings suggest that adding 0.25 μg/ml of astaxanthin improves the quality of porcine semen stored at 17°C. Our findings provide theoretical support for developing new protective agents critical for preserving pig semen at 17°C.

Enhancing astaxanthin yield in Phaffia rhodozyma: current trends and potential of phytohormones

Astaxanthin is an important ketocarotenoid with remarkable biological activities and high economic value. In recent times, natural astaxanthin production by microorganisms has attracted much attention particularly in pharmaceuticals, nutraceuticals, cosmetics, and food and feed industries. Though, currently, productivity is still low and has restricted scale-up application in the commercial market, microbial production of astaxanthin has enormous prospects as it is a greener alternative to the predominating chemical synthesis. Over the years, Phaffia rhodozyma has attracted immense interest particularly in the field of biovalorization and sustainable production of natural nutraceuticals as a promising source of natural astaxanthin since it is able to use agro-food waste as inexpensive nutrient source. Many research works have, thus, been devoted to improving the astaxanthin yield from this yeast. Considering that the yeast was first isolated from tree exudates, the use of phytohormones and plant growth stimulators as prospective stimulants of astaxanthin production in the yeast is promising. Besides, it has been shown in several studies that phytohormones could improve cell growth and astaxanthin production of algae. Nevertheless, this option is less explored for P. rhodozyma. The few studies that have examined the effect of phytohormones on the yeast and its astaxanthin productivity reported positive results, with phytohormones such as 6-benzylaminopurin and gibberellic acid resulting in increased expression of carotenogenesis genes. Although the evidence available is scanty, the results are promising. KEY POINTS: • Phaffia rhodozyma is a promising source of natural astaxanthin • For industrialization, astaxanthin productivity of P. rhodozyma still needs optimization • Phytohormones could potentially augment astaxanthin yield of P. rhodozyma.

Chlorophyll fluorescence as a valuable multitool for microalgal biotechnology

Variable fluorescence of chlorophyll (CF) of the photosynthetic apparatus is an ample source of valuable information on physiological condition of photosynthetic organisms. Currently, the most widespread CF-based technique is represented by recording pulse-amplitude modulated (PAM) induction of CF by saturating light. The CF-based monitoring techniques are increasingly employed for characterization of performance and stress resilience of microalgae in microalgal biotechnology. Analysis of CF induction curves reveals the fate of light energy absorbed by photosynthetic apparatus, the proportions of the energy that have been utilized for photochemistry (culture growth), and heat dissipated by photoprotective mechanisms. Hence CF and its derived parameters are an accurate proxy of the metabolic activity of the photosynthetic cell and the engagement of photoprotective mechanisms. This information is a solid foundation for making decisions on the microalgal culture management during the lab-scale and industrial-scale cultivation. Applications of CF and PAM include the monitoring of stressor (high light, nutrient deprivation, extreme temperatures, etc.) effects for assessment of the culture robustness. It also serves as a non-invasive express test for gauging the effect of assorted toxicants in microalgae. This approach is becoming widespread in ecological toxicology and environmental biotechnology, particularly for bioprospecting strains capable of the destruction of dangerous pollutants such as pharmaceuticals. In the review, we discuss the advantages and drawbacks of using CF-based methods for assessment of the culture conditions. Special attention is paid to the potential caveats and applicability of different variations of CF and PAM measurements for solving problems of microalgal biotechnology.

Recent Progress in Antioxidant Active Substances from Marine Biota

BACKGROUND

The well-recognized but not fully explored antioxidant activity of marine-biota-derived, biologically active substances has led to interest in their study as substitutes of antibiotics, antiaging agents, anticancer and antiviral drugs, and others. The aim of this review is to present the current state of the art of marine-biota-derived antioxidants to give some ideas for potential industrial applications.

METHODS

This review is an update for the last 5 years on the marine sources of natural antioxidants, different classes antioxidant compounds, and current derivation biotechnologies.

RESULTS

New marine sources of antioxidants, including byproducts and wastes, are presented, along with new antioxidant substances and derivation approaches.

CONCLUSIONS

The interest in high-value antioxidants from marine biota continues. Natural substances combining antioxidant and antimicrobial action are of particular interest because of the increasing microbial resistance to antibiotic treatments. New antioxidant substances are discovered, along with those extracted from marine biota collected in other locations. Byproducts and wastes provide a valuable source of antioxidant substances. The application of optimized non-conventional derivation approaches is expected to allow the intensification of the production and improvement in the quality of the derived substances. The ability to obtain safe, high-value products is of key importance for potential industrialization.

Astaxantin and Isoflavones Inhibit Benign Prostatic Hyperplasia in Rats by Reducing Oxidative Stress and Normalizing Ca/Mg Balance

Benign prostatic hyperplasia (BPH) is a common pathology among aging men. Despite the broad pharmacological interventions, the available remedies to treat BPH are yet not devoid of side effects. Herbal compounds are suggested to be an alternative option for the BPH treatment. In our study, we evaluated the effect of kudzu isoflavones and astaxanthin on the BPH animal model. The animals were randomly divided into five groups: control; testosterone-induced BPH group; and three BPH-induced groups, which received intragastrically for 28 days finasteride (5 mg/kg) as a positive control, isoflavones (200 mg/kg), and astaxanthin (25 mg/kg). BPH was induced by castration of animals and subsequent subcutaneous injections of prolonged testosterone (25 mg/kg). Prostate index and histology, biochemical parameters, and antioxidant activity were evaluated. A significant decrease in prostate weight, immunohistochemical markers, and normalization of prostate Ca/Mg ratio was found in all treatment groups. Astaxanthin treatment also resulted in decreased epithelial proliferation and normalized superoxide dismutase activity. In conclusion, both isoflavones and astaxanthin inhibited BPH development at a level comparable to finasteride in terms of prostate weight, prostatic epithelium proliferation, and prostate tissue cumulative histology score. These results suggest that isoflavones and especially astaxanthin could serve as a potential alternative therapy to treat BHP.

Astaxanthin alleviates neuropathic pain by inhibiting the MAPKs and NF-κB pathways

Neuropathic pain is a complex condition that usually lasts a lifetime and has a major negative impact on life after injury. Improving pain management is an important and unmet need. Astaxanthin (AST) is a natural marine medicine with effective antioxidant and anti-inflammatory properties and neuroprotective effects. However, few mechanisms can explain the role of AST in the treatment of neuropathic pain. In the present study, we examined its potential to eliminate spinal nerve ligation (SNL) damage by inhibiting the phosphorylation of extracellular signal-regulated kinase (ERK)1/2, phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), nuclear factor-κB (NF-κB) p65 and the inflammatory response. The results of behavior tests indicated the promising role of AST in analgesic effect in SNL mice. AST decreased the neuronal and non-neuronal activation, the levels of the inflammatory signaling mediators (p-ERK1/2 p-p38 MAPK and NF-κB p65) and inflammatory cytokine expression (interleukin [IL]-1, IL-17, IL-6, and tumor necrosis factor-α [TNF-α]. These results suggest that AST is a promising candidate to reduce nociceptive hypersensitization after SNL.

Recent Insights into the Nutritional Antioxidant Therapy in Prevention and Treatment of Diabetic Vascular Complications - A comprehensive Review

Diabetes mellitus (DM) and DM-induced vascular complications are a significant global healthcare problem causing a decrease in patient quality of life. The main reason for the disability and mortality of patients is rapidly progressing micro- and macroangiopathies. Currently, free radical oxidation is recognized as one of the main mechanisms in the development of DM and associated complications. Under normal physiological conditions, the level of free radicals and antioxidant defense capabilities is balanced. However, imbalance occurs between the antioxidant defense system and pro-oxidants during chronic hyperglycemia and may invoke formation of excess free radicals, leading to activation of lipid peroxidation and accumulation of highly toxic products of free radical oxidation. This is accompanied by varying degrees of insulin deficiency and insulin resistance in DM patients. Simultaneously with the activation of free radical generation, a decrease in the activity of antioxidant defense factors (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, vitamins C and E) and an acceleration of diabetic complications is seen. Therefore, we hypothesize that antioxidants may play a positive role in the treatment of DM patients to prevent DM-induced vascular complications. However this has not been sufficiently studied. In this review, we discuss recent insights into the potential underlying mechanisms of oxidative stress induced diabetic complications, and implications of antioxidants in mitigation of DM-induced vascular complications.