FLAVONOIDS: BIOCHEMISTRY, BIOPHYSICS, MEDICINE - Tarakhovsky Yu. S. - 2013

PART 1. MAJOR FLAVONOIDS

1.5. Flavanones

Flavanones (Fig. 11) are capable of stereoisomerism because they possess a single chiral center located at carbon atom 2 and can form two enantiomers: S-(-) and R-(+) (Fig. 12).

Class="center">Fig. 11. Selected representatives of flavanones.

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Fig. 12. Enantiomers of flavanones.

Currently, most commercial flavanones are presented as a racemic mixture of enantiomers. Exceptions are eriodictyol and homoeriodictyol, manufactured by Fluka (and some other companies) in the form of the pure S-(-)-enantiomer. The Role of stereoisomerism in the BIOLOGICAL EFFECTS OF these substances on animal and human organisms remains poorly understood so far.

1.5.1. Hesperetin and Hesperidin

Hesperetin and its glycoside hesperidin are present in citrus fruits, primarily in the pulp (the spongy part of the peel) of lemon (Citrus limon), bitter orange (Citrus aurantium, Linn.) (http://dic.academic.ru), mandarin (subspecies: Citrus unshiu Mar.), and sweet orange (Citrus sinensis). Another glycoside, hesperetin-7-rhamnoside, is found in Cordia (Cordia obliqua), which grows in South Asia.

Citrus pulp contains large amounts of hesperidin and carotenoids (β-cryptoxanthin), which potentially exert anticarcinogenic effects. Indeed, animal experiments have demonstrated that mandarin pulp and juices can protect animals against chemically induced forms of colorectal and Lung Cancer. Suppression of the expression of pro-inflammatory cytokines and inflammatory Enzymes was also observed. Hesperetin was significantly more active than apigenin and naringenin as a potential agent in breast cancer Treatment. It is hypothesized that its action may be based on the inhibition of aromatase, an enzyme involved in The conversion of testosterone to estradiol, which can drive carcinogenesis. Hesperidin also protected The Liver and Kidneys against oxidative stress resulting from free radical attack accumulating in the Blood of experimental animals. Feeding animals a diet containing hesperidin reduced the level of Lipid Peroxidation. In addition, the levels of ATP and Tricarboxylic Acid Cycle enzymes increased in Tissues.

Although protection against oxidative stress was observed in healthy Cells, studies on human Colorectal Cancer cells showed that hesperetin initiates apoptosis driven by an increase in lipid and protein oxidation products within the cells. Meanwhile, The activity of intracellular antioxidant enzymes—superoxide dismutase, catalase, and Glutathione peroxidase—decreased. The prooxidant/antioxidant balance is disrupted As a result of hesperetin's action on the mitochondrial Bax regulatory pathway. Within 24 hours, over 50% of cancer cells died at a hesperetin concentration of 70 nM, indicating the high anticarcinogenic activity of this agent in in vitro experiments. Hesperetin also induces apoptosis in carcinoma cells by acting on the Notch-1 membrane receptor, which leads to the suppression of the METABOLISM/31.html">Transcription factor expression (achaete-scute complex-like 1) and the parathyroid secretory protein chromogranin A, a precursor of several Peptide Hormones of the Endocrine System. Apoptosis is further enhanced by hesperidin-induced upregulation of the tumor suppressor p53 protein and inhibition of the NF-kB transcription control factor. Furthermore, hesperidin likely exerts its effects via the nuclear

PPAR-gamma (PPAR-y) receptor, which is responsible for the Regulation of Fatty acid and glucose metabolism. Through this regulatory pathway, hesperidin is hypothesized to control fat deposition in the body by hindering adipocyte proliferation.

Hesperidin is able to protect the epidermis from the damaging effects of ultraviolet B (UVB) radiation. In this process, hesperidin was shown to activate the expression of p53, the "guardian of The Genome" and transcription factor, thereby turning on the DNA Repair system damaged by UV light. Hesperidin also exhibits hepato- and nephroprotective activity in animals exposed to the potent allergen acetaminophen. In these animals, normalization was observed in the expression of proteases involved in inflammatory processes, as well as caspase-1, caspase-9, the transcription factor NF-kB, the nitric oxide-producing enzyme iNOS, and the apoptotic protein regulator BCL-2.

Hesperidin can serve as an anti-asthmatic agent acting as an agonist of Th cytokines related to interleukin 5, which is known to be responsible for The Development of allergic rhinitis and asthma. Treatment with hesperidin resulted in the suppression of eosinophil accumulation in the Lungs, a reduction in eotaxin buildup, and decreased production of specific IgE IMMUNOGLOBULINS. The ability of hesperidin to suppress asthmatic processes in the lungs of experimental animals has been confirmed in several other laboratories. It was found that hesperidin exhibited greater efficacy in suppressing asthmatic processes than naringenin or the widely used anti-inflammatory drug indomethacin, and no Toxic effects of hesperidin were observed.

Hesperidin is capable of exerting a sedative effect on The Nervous system by influencing opioid receptors. This is accompanied by the selective suppression of the extracellular signal-regulated kinase (ERK) pathway, which regulates numerous cellular processes including mitosis and Cell growth, and is also involved in carcinogenesis and viral infection progression. Hesperidin can protect neural tissue from damage under ischemic conditions. For instance, studies on animals with hippocampal ischemia showed that daily administration of hesperidin at 100 mg/kg of body weight significantly improved memory. This was accompanied by a decrease in lipid peroxidation levels, a reduction in nitrite concentrations, and an increase in antioxidant content. A key factor in hesperidin's action is likely The regulation of nitric oxide levels in tissues. In experimental stroke models, hesperidin was shown to reduce inflammatory processes in neural tissue. This was associated with an increase in the activity of antioxidant enzymes: glutathione peroxidase, glutathione reductase, catalase, and superoxide dismutase. Moreover, the observed reduction in free radical levels prevented the development of inflammation and neural tissue damage. Taken together, these findings suggest that hesperidin holds promise for the treatment of neurodegenerative diseases as a neuronal "survival mediator."

Hesperidin exerts a positive effect on the human Cardiovascular system. In 2011 alone, several independent clinical studies were conducted on the cardiovascular effects of purified hesperidin and orange juice. It was demonstrated that hesperidin is precisely the component responsible for the health-promoting effects of orange juice, the consumption of which (500 ml/day for four weeks) can significantly lower diastolic blood pressure. At the same time, an improvement in the leukocyte Gene Expression profile was observed in healthy volunteers. This study examined leukocyte genes responsible for chemotaxis, adhesion, infiltration, and Lipid Metabolism. A preparation of purified hesperidin exerted a similar effect.

Another independent clinical trial demonstrated that the consumption of orange juice, as well as a hesperidin Supplement (500 mg/day for three weeks), stimulated The production of nitric oxide by endothelial cells, thereby improving endothelial function and lowering the levels of inflammatory markers (serum amyloid A, C-reactive protein, soluble E-selectin) in the blood of patients suffering from Metabolic Disorders—metabolic syndrome, which is notoriously characterized by overweight, cardiovascular impairments, and Insulin resistance. Hesperidin consumption increased the phosphorylation of Src, Akt, and AMP-activated protein Kinases, as well as endothelial NO synthase, leading to the activation of NO synthesis.

The anti-inflammatory action of hesperidin may be linked to its ability to stimulate nitric oxide production by endothelial cells. It is hypothesized that hesperidin possesses vasoprotective properties and can be used in cases of endothelial dysfunction. The authors of another study investigating the effects of orange juice and pure hesperidin on healthy volunteers aged 50–65 arrived at a similar Conclusion, showing that hesperidin or juice consumed for four weeks significantly lowered diastolic blood pressure. Another clinical trial demonstrated that using hesperidin (the hesperetin glycoside) is not strictly necessary, since the bioavailability of hesperetin (the hesperidin aglycone) is very high due to its excellent Water solubility. Thus, as early as one hour after oral ingestion of 150 mg of hesperetin, its concentration in human blood reached 10.2 µM. Upon entering the body, the flavonoid undergoes glycosylation or sulfation, resulting in the presence of its derivatives (hesperetin 7-O-beta-d-glucuronide, hesperetin 3'-O-beta-d-glucuronide, hesperetin sulfate) in Blood Plasma. Furthermore, even a single dose of hesperetin was sufficient to elicit vasodilator effects in patients. Animal studies have shown that the greatest accumulation of hesperetin occurs precisely in the liver and aorta following its enhanced consumption over the course of a month.

It is also worth noting that hesperidin prevented the development of hypercholesterolemia on a Cholesterol-rich diet, contributed to weight loss in animals, lowered serum cholesterol levels, and prevented Fatty liver degeneration. Concurrently, the expression of several marker genes normalized, such as the myocardial ischemia marker and the cytoplasmic fatty acid-binding protein of cardiomyocytes, H-FABP.

1.5.2. Naringenin

Naringenin is present in grapefruit, oranges, and tomato peel. Clinical studies have shown that the bioavailability of naringenin is quite low. For example, when consuming fresh tomatoes, naringenin is virtually unabsorbed, but after heat treatment or when consumed as tomato paste, naringenin enters the bloodstream. The highest bioavailability was observed with the consumption of grapefruit juice. In this case, following juice intake at 8 ml/kg of body weight, blood naringenin concentrations can reach up to 6 µM/L. Grapefruit juice predominantly contains naringenin Glycosides: naringenin-7-rhamnoglucoside and naringenin-7-glucoside. Purated naringenin, much like hesperetin, rapidly enters the bloodstream, and its blood concentration can reach about 7 mmol/L after a single dose of 135 mg of naringenin. The high bioavailability of naringenin-7-O-glycoside found in Dracocephalum rupestre is well known. Recently, recombinant E. coli strains capable of producing a glycosylated form of naringenin—7-O-glycosyl naringenin—have been engineered, which features enhanced water solubility and bioavailability compared to non-glycosylated naringenin. A substantial increase in bioavailability and an enhancement of naringenin's therapeutic efficacy can be achieved by using nanoparticles for its blood transport.

Naringenin exhibits pronounced anticarcinogenic activity. Specifically, it can initiate apoptosis in lung cancer cells by activating the expression of a cytokine receptor—namely, tumor necrosis factor (TNF)-related apoptosis-inducing receptor, also known as a "death receptor"—and its corresponding protein Ligand TRAIL, which triggers cell death. It is suggested that co-treatment of tumors with the TRAIL ligand and naringenin could prove to be an effective and safe approach to suppressing carcinogenesis in resistant lung cancer cells. Animal experiments have also demonstrated that dietary naringenin significantly suppresses lung metastasis development. Based on naringenin, a novel agent has recently been synthesized: 5-hydroxy-7,4'-diacetyloxyflavamne-N-phenyl hydrazone, which also exhibits activity against lung cancer cells. Its activity is associated with the expression of the Fas ligand (a form of TNF), activation of the caspase cascade, and inhibition of the corresponding PI3K/Akt signaling pathway, leading to apoptosis in non-small cell lung cancer cells. Thus, the MECHANISM OF ACTION of this agent appears to be similar to that of naringenin. A comparable mechanism of naringenin-induced apoptosis was also discovered in earlier studies on human leukemia cells.

Naringenin is capable of initiating apoptosis in certain types of estrogen-stimulated cancer cells via alternative cell signaling pathways. For instance, naringenin induces rapid palmitic acid Cleavage (depalmitoylation) of the estradiol receptor on The Cell surface, leading to the dissociation of this receptor from caveolin, a protein responsible for hormone endocytosis. Additionally, naringenin activates the p38 protein kinase belonging to the mitogen-activated protein kinase (MAPK) family, which triggers tumor cell apoptosis.

Naringenin is also capable of inhibiting the proliferation of glioma cells, a form of Brain cancer, by modulating the apoptotic Proteins Bcl/Bax. This triggers the release of cytochrome c from Mitochondria and activates the Cx43 signaling pathway, which subsequently leads to the activation of caspase-3 and caspase-9, resulting in cellular apoptosis. Furthermore, both naringenin and apigenin can suppress colorectal carcinogenesis, as both agents initiate apoptosis and effectively reduce the proliferation of these cells. Additionally, the combined effects of naringenin and alpha-tocopherol on human prostate cancer cells have been observed to induce cell apoptosis, although the detailed mechanisms warrant further investigation.

Naringenin can exert protective effects across a wide range of human Organs and physiological systems, offering diverse cardiovascular benefits. For instance, it has been found to safeguard the myocardium from toxic agents. Doxorubicin, a widely used antineoplastic Chemotherapy drug, exhibits severe cardiotoxicity through the activation of Lipid peroxidation and apoptosis, which significantly limits its clinical application. Naringenin-7-O-glycoside, extracted from Dracocephalum rupestre, protects cardiomyocytes from doxorubicin-induced toxicity by upregulating the expression of cellular antioxidant enzyme genes. This expression is mediated by the activation of intracellular ERK-1/2 signaling kinases and the nuclear translocation of the Nrf2 factor. Pronounced myocardial protection against doxorubicin-induced toxicity is likewise achieved through the combined administration of naringenin and p-coumaric acid.

Like hesperetin, naringenin protects vascular endothelial cells by activating estrogen receptors, thereby elevating blood nitric oxide levels even under conditions of estrogen deficiency. However, their specific modes of action differ slightly: naringenin activates both alpha and beta estrogen receptor subtypes, whereas hesperetin preferentially activates estrogen receptor alpha, thereby enhancing nitric oxide synthase expression and NO concentration.

Naringenin can attenuate the progression of atherosclerosis in subjects maintained on a "Western diet," which is characterized by high consumption of red meat, refined grains, excessive CARBOHYDRATES, and fats. Such a diet induces a fivefold increase in blood triglycerides and an eightfold increase in cholesterol, alongside a tenfold rise in aortic atherosclerotic plaques. Dietary supplementation with naringenin successfully reduced blood cholesterol and triglyceride levels, diminished atherosclerotic plaques by over 50%, and decreased hepatic fat content by more than 80%, while also normalizing blood insulin levels and reversing obesity markers. Naringenin chalcone, a naringenin derivative found in tomatoes, normalizes adipose tissue adipocyte function and enhances the production of adiponectin—a hormone that regulates glucose and fatty acid metabolism while preventing insulin resistance, obesity, and diabetes. Citrus flavonoids such as hesperetin and naringenin can reduce the secretion of adipokines (inflammatory cytokines like TNF-α) by adipose tissue, which otherwise promote the release of free Fatty acids into the bloodstream, culminating in insulin resistance and type 2 diabetes. These flavonoids shift cellular metabolism toward lipid oxidation and inhibit the production of antilipolytic enzymes perilipin and PDE3B. Moreover, they prevent adipocyte hypertrophy and fat accumulation, instead inducing preadipocyte apoptosis and reducing adipose tissue mass.

Naringenin may prove effective in the management of diabetes. In experimentally induced diabetic animal models, a 21-day administration of naringenin yielded substantial improvements in blood parameters, comparable to those achieved in the control group treated with gliclazide, a well-known second-generation antidiabetic medication.

Numerous blood parameters were evaluated during the experiment. Alongside blood glucose levels, measurements included glycated Hemoglobin, insulin levels, pancreatic antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase), non-enzymatic antioxidants (glutathione, ascorbic acid, alpha-tocopherol), lipid peroxidation products (malondialdehyde), as well as the activities of Alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and Lactate dehydrogenase. The results demonstrated that naringenin exhibited antihyperglycemic and antioxidant efficacy comparable to gliclazide, while also increasing blood levels of enzymatic and non-enzymatic defense mechanisms against oxidative stress and hyperglycemia. Histopathological analyses confirmed naringenin's ability to prevent pancreatic tissue pathology. In a separate study, naringenin and quercetin displayed a cooperative synergistic effect in shielding animal models from diabetic complications, reducing damaged DNA levels in the blood, liver, and kidneys, lowering oxidative stress, and normalizing hematological profiles, which ultimately raised animal survival rates to 100%.

The anti-inflammatory properties of naringenin help protect the kidneys of diabetic subjects from nephropathy. This is achieved by downregulating renal tumor necrosis factor-alpha (TNF-α) expression and suppressing the production of pro-inflammatory cytokines, including interleukin-1β, interleukin-6, and monocyte chemoattractant protein-1, which drives monocyte migration from the bloodstream and their differentiation into macrophages during chronic inflammation. Naringenin also mitigates renal Connective Tissue fibrosis by repressing the expression of type IV Collagen, Fibronectin (a glycoprotein that anchors collagen to the cell surface), and TGF-β1, a polypeptide growth factor involved in cellular proliferation and apoptosis.

Naringenin suppresses airway inflammation in murine models of experimentally induced asthma. This effect is mediated through the inhibition of nuclear factor kappa B (NF-kB), a transcription factor that governs Immune Response gene expression and drives inflammatory and autoimmune disorders. Concurrently, it lowers the levels of specific interleukins and immunoglobulin E (IgE) associated with allergic reactions. Naringenin chalcone, present in tomato peels, also exhibits anti-asthmatic activity in animal models by inhibiting the production of Th2 cytokines derived from CD4⁺ T-helper lymphocytes.

Naringenin inhibits the GENERATION AND PROPAGATION of inflammatory signaling within neuroglia, thereby protecting the brain against inflammatory injuries that lead to neurodegeneration. In comparative evaluations across a broad spectrum of flavonoids (flavones, flavonols, and anthocyanidins), naringenin demonstrated the most pronounced efficacy. This is attributed to its capacity to suppress inducible nitric oxide synthase expression, lower glial NO concentrations, inhibit the phosphorylation of mitogen-activated protein kinase (MAPK), and consequently block STAT-1—a downstream transcription activator linked to the Regulation of Immune tolerance and carcinogenesis.

Naringenin can mitigate heavy metal intoxication involving elements such as cadmium, lead, and arsenic. Although cadmium is a relatively rare metal with a crustal Abundance of 0.5 ppm, its extraction surged by tens of thousands of times during the 20th century, currently reaching 20,000 tons annually. Cadmium poisoning is partly driven by improper disposal of nickel-cadmium batteries and electronic waste, alongside industrial extraction and Processing of zinc ores. Exposure typically occurs via inhalation of cadmium fumes or ingestion of water-soluble salts present in foodstuffs. Acute Poisoning initially presents as fever, while severe cases can progress to Pneumonia, pulmonary edema, and even death. Lead induces dysfunction across the circulatory, hepatic, and renal systems, with the nervous system being exceptionally vulnerable; even low-level lead exposure impairs cognitive function and learning capacity in children. Despite its high toxicity, arsenic salts have been utilized in European medicine for centuries and in Traditional Chinese Medicine for approximately 5,000 years. The toxicity of arsenates stems from their ability to trigger oxidative stress, whereas arsenites can disrupt cellular signaling and potentially initiate carcinogenesis. Naringenin counteracts metal-induced oxidation and alleviates the Adverse effects of oxidative stress. For instance, naringenin administration demonstrated protective effects against cadmium-induced hepatic and renal injuries, with analogous results observed in lead and arsenic exposure models. The therapeutic action of naringenin stems not only from its intrinsic antioxidant properties and metal-chelating ability, but primarily from its capacity to modulate cellular regulatory systems and activate endogenous defense mechanisms. This is marked by elevated intracellular levels of antioxidant enzymes, including superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, glutathione reductase, glucose-6-phosphate dehydrogenase, alkaline phosphatase, and lactate

dehydrogenase, aspartate aminotransferase, among others. Simultaneously, naringenin inhibits cytochrome P450—an Endoplasmic reticulum protein in hepatocytes and renal cells that serves as a primary agent of systemic detoxification. Because this enzyme catalyzes The oxidation of toxic Organic compounds, dampening its activity can reduce the concentration of oxidation byproducts.

Naringenin exhibits notable antibacterial and antiviral properties. Experimental studies have demonstrated the ability of naringenin and hesperetin to suppress the growth of methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, naringenin may help combat hepatitis C virus (HCV) infection, a persistent pathogen affecting approximately 3% of the global human population. Hepatocyte-based studies revealed that naringenin's antiviral efficacy is comparable to that of interferon, albeit via a fundamentally distinct mechanism. Naringenin does not interfere with viral Protein Synthesis within the host cell, but instead disrupts viral particle assembly. This assembly process requires host cell Lipids alongside viral proteins; naringenin alters the virus's utilization of these lipids, leading to a dramatic reduction in viral progeny. This effect is likely mediated by naringenin's activation of PPAR-α, a transcription factor governing lipid metabolism that initiates fatty acid Beta-Oxidation. Combining naringenin with standard antiviral pharmacotherapy may hold significant promise for infection management.

1.5.3. Eriodictyol

Eriodictyol was originally isolated from Eriodictyon californicum, a herbaceous plant native to North America. Eriodictyol and its glycosides are also found in various fruit juices, tea (Camellia sinensis), citrus fruits such as lemons (Citrus limon), tomatoes (Solanum lycopersicum), rose hips (Rosa canina), hawthorn hybrids (Crataegus × macrocarpa), savory (Satureja obovata Lag.), Siberian pine seeds (Pinus sibirica), the phloem of Siberian larch (Larix sibirica Ledeb.) and Gmelin larch (Larix gmelinii Rupr.), South African rooibos (Aspalathus linearis), honeybush (Cyclopia genistoides), and the Mediterranean snapdragon (Antirrhinum majus), commonly known as the dragon flower.

While relatively few studies have explored the Physiological effects of eriodictyol, investigations into this flavanone are considered exceptionally promising. Recently, eriodictyol was identified as a suppressor of RSK2 kinase activity and the AMPK-dependent transcription factor ATF1, both of which drive cancer cell proliferation and neoplastic transformation. Eriodictyol exerts pro-oxidant activity in malignant cells, causing DNA damage and cancer cell death, while exerting a protective effect in normal cells. For instance, eriodictyol exhibits antioxidant and anti-apoptotic actions in ultraviolet-irradiated keratinocytes. UV radiation can suppress protein phosphatase 2A (PP2A), an enzyme that regulates p38 MAPK and Akt protein kinases responsible for apoptosis.

Eriodictyol suppresses macrophage responses to bacterial lipopolysaccharides, which are potent Inducers of inflammation. This effect is achieved by restoring PP2A activity, re-establishing regulatory control over the p38 MAPK and Akt signaling pathways, and lowering nitric oxide levels. Furthermore, eriodictyol enhances cellular resilience to oxidative stress by activating internal antioxidant defenses. This defense activation is initiated through the nuclear translocation of the Nrf2 transcription factor, which upregulates antioxidant enzyme expression. Consequently, this leads to elevated expression of heme oxygenase-1 and NAD(P)H quinone oxidoreductase, as well as increased intracellular glutathione concentration, resulting in a dramatic boost in cell survival.

Eriodictyol may confer beneficial cardiovascular effects by acting as a vasorelaxant. For instance, it counteracts norepinephrine-induced vasoconstriction and inhibits vascular reactivity to calcium chloride and phorbol esters.

1.5.4. Diosmin

Diosmin is formally classified as a flavone, yet for pharmaceutical Applications, it is synthesized via the chemical Modification of the flavanone hesperetin, earning it the designation of a "semisynthetic diosmin." Natural sources of diosmin also exist, as it is naturally present in citrus fruits. Immature citron fruits (Citrus medica)—particularly the "Buddha's hand" cultivar—and Meyer lemons are especially rich in diosmin. Green, unripe fruits are preferred over mature, edible specimens because the latter contain significantly lower diosmin concentrations, rendering them of little pharmacological value. Diosmin is also found in the leaves of the South African buchu plant (Agathosma) and hyssop (Hyssopus officinalis), which is widely distributed across Eurasia and Africa.

Diosmin serves as the primary active ingredient in several popular medications used for vascular disorders, such as Phlebodia (active pharmaceutical ingredient: semisynthetic diosmin), Daflon (containing micronized semisynthetic diosmin and hesperetin in a 9:1 ratio), and Daflon formulations comprising micronized flavonoid mixtures (including diosmin extracted from Cissus quadrangularis L., a member of the Vitaceae family). These medications are recommended for chronic venous insufficiency, capillary fragility, and hemorrhoids. Therapeutic regimens typically involve administering 500–600 mg of flavonoids one to two times daily over periods ranging from several weeks to many months. Five major European clinical trials evaluating diosmin (Daflon) in patients with severe venous trophic ulcers demonstrated that this venotonic agent constitutes a valuable and effective adjunct in the comprehensive management of severe chronic venous insufficiency.

Conversely, clinical trials conducted in 2010 on Daflon derived from Cissus quadrangularis L. revealed no significant therapeutic differences compared to placebos in treating early-stage hemorrhoidal symptoms, failing to demonstrate positive clinical dynamics relative to the control group. Nevertheless, other clinical evaluations highlight Daflon as an effective and safe intervention for various hemorrhoidal symptoms and lower-limb edema.

Although Phlebodia is manufactured by the French pharmaceutical company Innotech, clinical trials evaluating its efficacy have been conducted primarily in Russia and Eastern Europe (Serbia, Bulgaria). A substantial body of literature in domestic journals documents clinical observations of Phlebodia's efficacy across various vascular pathologies (http://medi.ru/doc/a240900.htm). The drug has also yielded favorable outcomes in obstetrics and gynecology, where it is successfully utilized to treat pelvic varices and placental insufficiency. Additionally, Phlebodia finds clinical application in lymphovenous insufficiency, lower-limb varicosities, proctology, urology, neurology, and oncology.

The long-term consequences of prolonged diosmin-based pharmacotherapy remain poorly understood, and this agent carries potential adverse side effects. For instance, a solitary case of cerebral ventricular Hemorrhage was reported in an elderly female patient who had taken diosmin for several years. According to the study authors, this hemorrhagic event may be linked to diosmin's inhibitory effect on platelet aggregation combined with its potentiation of norepinephrine-induced vasoconstriction, which elevates capillary pressure. The synergy of elevated vascular pressure and impaired hemostasis can precipitate hemorrhages.

As demonstrated in animal models, diosmin exerts multifaceted cardiovascular effects: it normalizes blood pressure, regulates nitric oxide levels, elevates antioxidant concentrations, and reduces lipid peroxidation byproducts in the bloodstream. Diosmin mitigates the cytotoxic impact of bacterial lipopolysaccharides on aortic endothelial cells and Neurons, thereby offering protection against neurodegenerative disorders. Lipopolysaccharides trigger apoptosis primarily by inducing tumor necrosis factor-alpha (TNF-α); diosmin exerts cytoprotection by inhibiting TNF-α production, preserving DNA structural integrity, and suppressing caspase-3 activation. Consequently, diosmin delivers neuroprotective and anti-inflammatory benefits to neural tissues.

Preclinical studies on animals and cell cultures indicate that diosmin possesses a diverse pharmacological profile, pointing toward broad therapeutic potential. Several animal studies demonstrated that diosmin can suppress pulmonary melanoma metastasis. Its anti-invasive activity was comparable to that of alpha-interferon—a drug burdened by severe toxicity, unlike diosmin. Furthermore, these agents act synergistically, allowing for a substantial reduction in the required dosage of alpha-interferon. Diosmin exhibited nearly double the potency of grape seed extract or red wine in suppressing cancer cell proliferation in vivo. Its antimetastatic efficacy also surpassed that of rutin and tangeritin. Diosmin-induced inhibition of hepatocellular carcinoma cell proliferation and G2/M phase Cell Cycle arrest likely stems from the activation of the p53 tumor suppressor protein, which downregulates the PI3K-Akt-MDM2 signaling axis. Additionally, the combination of diosmin and hesperetin effectively inhibited the proliferation of bladder, colorectal, and oral cancer cells.

Diosmin has the potential to exert a beneficial effect on diabetic patients. It exhibits multifaceted action by influencing Carbohydrate Metabolism. When administered daily at a dose of 100 mg/kg of body weight, significant Changes in the blood are observed: hemoglobin glycosylation decreases, the content of normal hemoglobin increases, and insulin concentration rises. The activity of key liver enzymes significantly increases—

such as hexokinase and glucose-6-phosphate dehydrogenase, whereas the activity of glucose-6-phosphatase and fructose-1,6-bisphosphatase decreases. At the main time, diosmin protects the body against the manifestations of oxidative stress that accompanies the Development of the disease. The activity of antioxidant enzymes in the blood increases—including superoxide dismutase, catalase, glutathione peroxidase, and glutathione transferase—along with the levels of antioxidant molecules such as Vitamin C, vitamin E, and reduced glutathione.

The anti-inflammatory effects of hesperetin and diosmin were studied in animals with experimentally induced colitis. In the presence of diosmin, a decrease was observed in the concentration of the lipid peroxidation product malondialdehyde, as well as a reduction in the concentration of leukotriene B4, which is involved in the development of inflammatory processes. Hesperetin did not exhibit a similar effect, but, much like diosmin, it enhanced fluid Absorption in the colon, which was crucial for this condition. Thus, diosmin and hesperetin are capable of preventing colitis-induced inflammatory processes, wherein protection against oxidative stress may play a significant role. A mixture of hesperetin and diosmin (the drug Daflon) can inhibit the development of radiation-induced proctitis, which also demonstrates the anti-inflammatory efficacy of these substances in intestinal pathologies.