Flavonoids are polyphenolic compounds of plant origin, recognized for their antioxidant, anti-inflammatory, and protective properties. Found in a wide variety of plants, they play a key role in pigmentation, cell defense, and ecological interactions. In this article, we explore in depth their classification, their benefits for human health, their main food and medicinal sources, and the challenges related to their quantification. quantification of flavonoids —by HPLC, spectrophotometry, or mass spectrometry—is essential to guarantee the quality of plant extracts, validate health claims, and meet regulatory requirements in the nutraceutical, cosmetic, food, and pharmaceutical sectors.
Table of Contents
What is a flavonoid? Definition and classification
Definition of flavonoids
Flavonoids are plant-derived polyphenols characterized by a common chemical structure composed of two aromatic rings linked by a chain of three carbon atoms (C6-C3-C6). They belong to the family of secondary metabolites, produced by plants to protect themselves against various environmental stresses such as ultraviolet radiation, pathogens, and herbivores.
These compounds were discovered in 1936 by Albert Szent-Györgyi, who initially named them vitamin P , due to their supposed role in capillary permeability. Since then, more than 6,000 flavonoids have been identified in various plant species.
Flavonoids are found primarily in the form of glycosides , meaning they are bound to sugars, which influences their solubility and bioavailability. Their absorption in the body depends on the specific chemical structure of each flavonoid as well as its interactions with the gut microbiota.
The different classes of flavonoids
Flavonoids are classified into several classes based on their structure and biochemical properties. Each class has specific characteristics and is found in particular plant sources.
Flavones
Flavones are compounds with recognized antioxidant and anti-inflammatory properties. They are found in plants such as parsley, celery, and certain flowers.
Examples:
- Luteolin (found in chamomile and thyme)
- Apigenin (found in celery and dandelion)
Flavonols
Flavonols are the most widespread of the flavonoids and possess strong antioxidant activity. They are found in particular in onions, apples and grapes.
Examples:
- Quercetin (found in onions and berries)
- Kaempferol (found in broccoli, green tea)
Flavanones
These flavonoids are found mainly in citrus fruits and contribute to their slightly bitter taste.
Examples:
- Naringenin (in grapefruit)
- Hesperetin (found in oranges and lemons)
Flavanols (or catechins)
Flavanols, also known as catechins , are abundant in green tea and cocoa. They possess interesting cardiovascular properties and contribute to the protection of the vascular system.
Examples:
- Epigallocatechin gallate (EGCG, in green tea)
- Procyanidins (present in grapes and red wine)
Anthocyanins
Isoflavones
Found primarily in legumes, isoflavones have estrogenic properties and are being studied for their effects on hormonal health.
Examples:
- Genistein (in soybeans)
- Daidzein (in soybeans)
Flavanonols
Flavanonols are an intermediate subclass between flavonols and flavanones. They are distinguished by the absence of a double bond between carbons C2 and C3 and are found in certain plants with antioxidant and anti-inflammatory properties.
Examples:
- Taxifolin (dihydroquercetin, present in Dahurian larch and certain berries)
Role of flavonoids in plants
Flavonoids perform various essential functions for plant development and survival:
- UV protection : they absorb ultraviolet radiation and prevent oxidative damage to plant cells.
- Defense against pathogens : some flavonoids possess antifungal and antibacterial properties.
- Attracting pollinators : anthocyanins and flavones color the petals of flowers, thus guiding insects towards the nectar.
- Interaction with nitrogen-fixing bacteria : the roots of certain plants (alfalfa, peas) release flavonoids to attract symbiotic bacteria of the genus Rhizobium, thus facilitating the fixation of atmospheric nitrogen.
In an industrial context, the presence of flavonoids in plant extracts can influence the properties of finished products. For example, their ability to absorb UV rays is exploited in the cosmetics industry to formulate natural sunscreens, while their antioxidant effect is valued in nutraceuticals and the food industry.
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Properties and health benefits of flavonoids
Antioxidant and anti-inflammatory properties
Flavonoids are widely recognized for their antioxidant action, meaning they neutralize free radicals generated during metabolic processes and in cases of environmental stress.
Studies have shown that certain flavonoids, such as quercetin and kaempferol, have a higher antioxidant capacity than classic vitamins such as vitamin C or E. For example, research indicates that a moderate concentration of quercetin can reduce oxidative damage by more than 40% in in vitro models.
Furthermore, these molecules also exert anti-inflammatory effects by inhibiting the activation of pro-inflammatory mediators, such as interleukin-1β and tumor necrosis factor. These properties make flavonoids promising candidates for the prevention of chronic inflammatory diseases, including arthritis and certain cardiovascular conditions.
Effects on the cardiovascular system
Flavonoids play a vital role in protecting the cardiovascular system. Their ability to improve endothelial function and reduce platelet aggregation contributes to the prevention of atherosclerosis.
Epidemiological studies, including a meta-analysis of over 50,000 participants, have shown that regular flavonoid consumption is associated with a 20% reduction in the risk of major cardiovascular events. By improving vasodilation and lowering blood pressure, flavonoids promote better blood circulation and limit the development of hypertension.
Impact on neurocognitive health
Flavonoids also have beneficial effects on brain health. They possess neuroprotective potential, notably by modulating the activity of signaling pathways involved in neuronal plasticity and memory.
Preliminary research suggests that flavonoid consumption may improve cognitive function in older adults. For example, clinical studies have reported that flavonoid supplementation, such as EGCG found in green tea, can improve working memory scores by 15% in subjects with mild cognitive impairment.
Effects on the gut microbiota and bioavailability
The impact of flavonoids on the gut microbiota is a rapidly growing area of research. These compounds are not only absorbed directly in the gut, but they also interact with the gut flora. Certain bacteria can metabolize flavonoids into bioactive metabolites, which could have beneficial effects on digestive and immune health.
However, the bioavailability of flavonoids generally remains low due to their limited solubility and rapid metabolism in the gastrointestinal tract. Innovative encapsulation and formulation techniques are being developed to improve the absorption and efficacy of these molecules.
Risks and drug interactions
Despite their numerous benefits, flavonoids can present certain risks and drug interactions. Indeed, excessive intake of flavonoid-rich dietary supplements can lead to adverse effects, such as digestive problems or headaches. Furthermore, drug interactions have been identified, particularly with statins and certain anticoagulants.
Quercetin, for example, can inhibit the activity of certain enzymes involved in the metabolism of these medications, which could lead to an increase in their plasma concentrations. Therefore, it is recommended that individuals taking medication consult a healthcare professional before considering flavonoid supplementation.
The antioxidant, anti-inflammatory, and cardiovascular properties of flavonoids make these compounds valuable allies in the prevention of chronic diseases. Their positive impact on neurocognitive and digestive health, combined with careful management of potential risks, opens up promising prospects in the field of nutraceuticals and overall health.
Why analyze flavonoids in the laboratory?
Laboratory analysis of flavonoids is of paramount importance to several industries, including food, nutraceuticals, cosmetics, and pharmaceuticals. These analyses allow for the evaluation of the concentration and efficacy of these bioactive compounds, ensure product quality and traceability, and guarantee compliance with applicable regulations. In a context where health claims and product naturalness are essential criteria for consumers, having reliable and accurate data on flavonoid content is indispensable.
Importance for the agri-food industry
Flavonoids are widely present in fruits, vegetables, teas, wines, and other food products. In the food industry, their analysis is essential for several reasons:
- Raw material quality control : Flavonoid content varies depending on growing conditions, climate, harvesting method, and processing methods. Analysis ensures product standardization and guarantees a consistent level of bioactive compounds.
- Adding value to food products : Numerous studies have shown that consumers are increasingly seeking foods rich in natural antioxidants. Identifying and quantifying flavonoids in certain products, such as fruit juices or herbal teas, allows us to highlight their health benefits.
- Verification of health claims : European (EFSA) and American (FDA) regulations impose strict criteria for the use of claims on food products. Precise measurement of flavonoids is necessary to justify claims such as "rich in antioxidants" or "promotes cell protection."
Role in food supplements and nutraceuticals
The market for dietary supplements and nutraceutical products is experiencing exponential growth. Flavonoids, due to their beneficial health effects, are often used as active ingredients in these formulations.
- Verification of active ingredient concentrations : The presence and content of flavonoids in plant extracts must be controlled to ensure optimal efficacy and avoid underdosing or overdosing.
- Formulation stability : Some flavonoids, such as anthocyanins, are sensitive to light, oxygen, and temperature. Regular analyses allow for the evaluation of their stability over time and the optimization of storage conditions.
- Regulatory compliance : Food supplements must meet strict safety and efficacy standards. In Europe, the EFSA requires robust scientific evidence before authorizing health claims, which necessitates rigorous laboratory testing.
Interest in the cosmetics industry
Ensuring traceability and regulatory compliance
In cosmetics, flavonoids are used for their antioxidant, anti-inflammatory, and photoprotective properties. Their laboratory analysis is essential for several reasons:
- Validation of cosmetic claims : Brands claiming anti-aging, protective, or soothing effects must prove the presence and efficacy of flavonoids in their formulations. Analytical tests allow for the quantification of these molecules and the evaluation of their biological activity.
- Formulation optimization : Some flavonoids, such as quercetin and kaempferol, have low bioavailability and require specific techniques to stabilize them in creams or serums. Analysis allows us to measure their effectiveness after incorporation into a finished product.
- Compliance with safety standards : The cosmetics industry is subject to strict regulations regarding ingredient safety. Flavonoid analysis helps identify potential impurities or contaminants and ensures the absence of undesirable compounds.
Flavonoid analysis is not limited to their quantification. It also ensures the traceability of natural ingredients and meets regulatory requirements for quality control.
- ISO 17025 Standards : Laboratories accredited according to the ISO 17025 standard guarantee reliable and reproducible results.
- Food and pharmaceutical regulations : The presence of flavonoids in products intended for human consumption is governed by specific guidelines. For example, food supplements containing flavonoids must comply with the dosages authorized by the EFSA.
- Contamination and impurity testing : Some flavonoids may contain solvent residues or be contaminated by pesticides. Laboratory analyses can identify these contaminants and ensure consumer safety.
Flavonoid analysis is therefore a key element for industries that want to guarantee the quality, safety, and efficacy of their products. In the following section, we will explore the different methods used in the laboratory to accurately identify and quantify these compounds.
How to analyze and quantify flavonoids in the laboratory?
Laboratory analysis of flavonoids relies on advanced techniques that allow for the precise quantification of these compounds and the evaluation of their profile in various plant, food, pharmaceutical, and cosmetic matrices. These analyses are essential for guaranteeing product quality, validating health claims, and ensuring regulatory compliance.
Analysis procedures: commonly used techniques
The identification and quantification of flavonoids require robust analytical methods capable of detecting very low concentrations and differentiating the different classes of flavonoids present in a sample.
High-performance liquid chromatography (HPLC)
chromatography (HPLC) is the reference method for flavonoid analysis. This technique allows for the precise separation, identification, and quantification of each molecule present in a sample.
Principle of HPLC:
- A liquid sample is injected into a chromatographic column containing a stationary phase.
- A solvent (mobile phase) is used to carry the compounds through the column.
- Each flavonoid is retained differently depending on its chemical properties, allowing their separation.
- A UV-Visible detector or mass spectrometry (HPLC-MS) allows each molecule to be identified and quantified.
Laboratory applications:
- Dosage of flavonoids in plant extracts used in herbal medicine.
- Control of flavonoid content in fruit juices, tea and wine.
- Verification of the stability of flavonoids in cosmetics and food supplements.
UV-Vis spectrophotometry
UV-Visible spectrophotometry is a rapid and efficient method for measuring the total concentration of flavonoids in a sample. It is based on the absorption of light by these compounds at a specific wavelength.
Principle of UV-Vis spectrophotometry:
- A sample containing flavonoids is dissolved in a solvent.
- A light source sends a beam through the sample.
- The spectrophotometer measures the absorption of light, which is proportional to the concentration of flavonoids.
Applications:
- Rapid analysis of the total flavonoid content in plant raw materials.
- Control of flavonoid stability in cosmetic formulations.
- Verification of "rich in antioxidants" claims for food products.
Mass spectrometry (LC-MS, GC-MS)
mass spectrometry ( LC-MS or GC-MS) is an advanced technique that allows for the precise identification of the chemical structure of flavonoids and the detection of their presence at very low concentrations.
Principles of mass spectrometry:
- Flavonoids are separated by liquid chromatography (LC-MS) or gas chromatography (GC-MS).
- The molecules are ionized, then fragmented into characteristic ions.
- A mass spectrometer analyzes the mass of the fragments to identify each flavonoid with high precision.
Applications:
- Identification of specific flavonoids in complex plant extracts.
- Detection of trace amounts of flavonoids in pharmaceutical formulations.
- Analysis of the interactions between flavonoids and other bioactive compounds.
Specific tests depending on the application sector
Flavonoid analysis varies depending on the type of product and its sector of application.
Dietary supplements
- Dosage of active flavonoids to guarantee optimal effectiveness.
- Stability tests to ensure consistent concentration over time.
- Contaminant control (heavy metals, pesticides) to meet safety standards.
Cosmetics
- Evaluation of antioxidant properties to confirm the anti-aging effect of the formulations.
- Photostability tests to ensure that flavonoids do not degrade under the effect of UV light.
- Validation of interactions with other active ingredients to avoid any instability of the formulation.
Agri-food
- Flavonoid analysis in fermented products such as wine and tea.
- Control of flavonoid levels in plant juices and extracts to guarantee their nutritional quality.
- Migration tests for food packaging , to assess whether flavonoids are released into food.
Laboratory analysis of flavonoids relies on advanced methodologies tailored to the needs of manufacturers. These tests ensure optimal product quality and meet the expectations of consumers and regulatory authorities. In the next section, we will see how YesWeLab supports companies in flavonoid analysis through its expertise and network of laboratories.
YesWeLab's expertise in flavonoid analysis
YesWeLab is a key player in flavonoid analysis for the food, cosmetics, nutraceutical, and pharmaceutical industries. Through its network of over 200 ISO 17025 accredited partner laboratories , YesWeLab offers a comprehensive range of analytical services to guarantee the quality, traceability, and compliance of flavonoid-containing products.
YesWeLab's approach is based on three fundamental pillars: an innovative digital platform , advanced analysis methods , and personalized support for each industrial client .
A digital platform to centralize analyses
YesWeLab offers an online platform that allows manufacturers to easily manage their laboratory analyses. This digital solution simplifies the ordering process and ensures complete transparency in sample tracking and results receipt.
Quick and secure access to analyses
Thanks to the YesWeLab platform, companies can:
- Select the desired analyses from a wide range of services.
- Track the progress of tests in real time using an intuitive dashboard.
- Download the analysis reports as soon as they are available, with detailed results interpreted by experts.
Reduction of execution times
One of the major advantages of the YesWeLab platform is the reduction of analytical turnaround times . By centralizing requests and optimizing sample shipping logistics, YesWeLab guarantees fast turnaround times while maintaining impeccable analytical quality.
A network of accredited and specialized laboratories
YesWeLab collaborates with laboratories specializing in flavonoid analysis, guaranteeing reliable results that comply with regulatory requirements.
ISO 17025 Accreditation
YesWeLab's partner laboratories are ISO 17025 , the international standard guaranteeing technical competence and reliability of results.
Expertise tailored to each industrial sector
YesWeLab offers customized analyses tailored to the needs of businesses:
- Food industry : control of flavonoids in beverages, plant extracts and fermented products.
- Nutraceuticals : Flavonoid dosage in food supplements to validate health claims.
- Cosmetics : verification of antioxidant properties and stabilization of formulations.
- Pharmaceutical : identification of flavonoids in medicines and extracts of medicinal plants.
Examples of analyses performed by YesWeLab
YesWeLab provides manufacturers with cutting-edge analytical methods to guarantee the quality and safety of products containing flavonoids.
Flavonoid dosage in medicinal plant extracts
Plant extracts are widely used in the pharmaceutical and nutraceutical industries for their beneficial effects on health. YesWeLab performs precise analyses to determine the flavonoid concentration in plants such as ginkgo biloba, green tea, St. John's wort, and red vine .
Verification of health claims for food supplements
Dietary supplements claiming antioxidant or anti-inflammatory properties must be supported by reliable analyses. YesWeLab offers specific tests to confirm the presence and efficacy of active flavonoids, thus guaranteeing compliance with EFSA requirements.
Stability study of flavonoids in cosmetic formulations
Cosmetic products containing flavonoids, such as anti-aging creams and antioxidant serums, must ensure optimal stability of their active ingredients. YesWeLab conducts photostability, oxidation, and interaction tests with other components to optimize formulations.
Tailored support and expert advice
YesWeLab does more than just provide analytical results. Its team of experts supports manufacturers at every stage of the analysis process.
Product development consulting
Companies wishing to formulate flavonoid-enriched products can benefit from YesWeLab's advice on:
- Choose the most suitable plant sources based on their flavonoid profile.
- Optimize extraction processes to maximize the concentration of bioactive compounds.
- Evaluate the impact of storage conditions on flavonoid stability.
Regulatory assistance
YesWeLab helps its clients comply with European and international regulations regarding product labeling, health claims, and safety. YesWeLab experts conduct compliance studies according to EFSA and FDA criteria.
Why choose YesWeLab for flavonoid analysis?
Thanks to its expertise and network of specialized laboratories, YesWeLab is the ideal partner for companies wishing to guarantee the quality and safety of their products containing flavonoids.
The key advantages of YesWeLab include:
- Quick and easy access to analyses thanks to an innovative digital platform.
- Reliable results that comply with ISO 17025 standards.
- Expertise tailored to industrial needs in the agri-food, nutraceutical, cosmetic and pharmaceutical sectors.
- Personalized support with expert advice on formulation, stability and regulatory compliance.
Flavonoid analysis plays a central role in validating natural products and ensuring their quality. Thanks to its high-performance analytical solutions, YesWeLab helps manufacturers optimize their formulations, guarantee the traceability of their ingredients, and comply with health authority requirements.
