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Effects of Flavonoids on Skin according to Their Structural Characteristics: A Review
Abstract
Functional materials with anti-aging properties that prevent aging in the human body in advance have been attracting attention in the pharmaceutical, food, and cosmetic industries, and active research regarding cosmetic ingredients employing flavonoids among such substances is underway. Therefore, this general review assessed previous studies regarding the effect of various flavonoids on the skin according to their structural characteristics. In this study, the antioxidant, whitening, and antiinflammatory effects of flavonoids present in natural extracts were analyzed. Among the flavonoids, the collagen activity enhancing, antioxidant, anti-inflammatory, and whitening effects of apigenin, baicalein, genistein, naringenin, hesperetin, proanthocyanidins, quercetin, and kaempferol were evaluated. In addition, a study conducted to increase the bioavailability of flavonoids by converting them into clathrates using the structural characteristics of β-cyclodextrin, which further analyzed the difference in the effects of glycoside-containing and non-glycoside flavonoids, was reviewed. Another study reported that the 3'-hydroxyl functional group of flavonoids plays an important role in their antioxidant and anti-inflammatory activities; hence, effects consequent to the modification of their molecular structure were expected. Therefore, the studies that suggest that structural modifications can supplement the efficacy of verified flavonoids are considered to be valid. In future, flavonoids may be used as a stable anti-aging material on the basis of this study on their effects on the skin according to their structural characteristics.
... Flavonoids are secondary plant metabolites and among the most common polyphenol compounds ingested by humans. They are powerful antioxidants that can be obtained from nature because of their strong action as free radical scavengers and reactivity with hydroxyl radicals [11]. ...
Because of its long history of use in traditional medicine, Flemingia macrophylla has attracted a lot of attention from the fields of phytochemistry and pharmacology. However, a comprehensive research data on its phytochemistry and pharmacological roles have not been found in the literature. This comprehensive review combines the abundance of information regarding the traditional application, phytochemical makeup, and pharmacological properties, demonstrating its critical role in the traditional Chinese medicine. Examining its past uses in many cultural contexts from treating gastrointestinal issues to treating dermatological conditions highlights its extraordinary adaptability. This article reveals the generations-long development of Flemingia macrophylla as a reliable Chinese medicine through an examination of ethnobotanical records. Its phytochemical composition is carefully examined in this review, which reveals a complex array of chemicals including flavonoids, alkaloids, and terpenoids that are crucial to comprehending the plant's potential as a medicine. Determining the pharmacological consequences of the bioactive components of this plant components requires a thorough structural clarification. Pharmacological studies demonstrate a range of actions, including antiinflammatory, antioxidant, and cardiovascular benefits, consistent with its conventional applications. Its antifungal function in particular highlights how useful it is against microbial dangers in general. Throughout, the paper highlights how conventional knowledge and contemporary pharmacology are convergent, emphasizing the mutually beneficial interaction between cultural legacy and evidence-based treatment. Encapsulating the historical significance and current relevance of Flemingia macrophylla in the integration of traditional Chinese medicine into modern healthcare practices, this comprehensive compilation could be an invaluable resource for researchers, herbalists, and healthcare practitioners.
The use of medicinal plants that produce a secondary metabolite continues to grow along with population growth. One of these species is Campomanesia sessiliflora (O. Berg) Mattos. The literature reports that C. sessiliflora is rich in phenolic compounds and flavonoids, which possess high anti-aging activity and can be utilized in the cosmetic and food industries. Optimizing the extraction of bioactive compounds from this plant is crucial for its industrial application. Currently, Campomanesia sessiliflora leaves are discarded as pruning waste. The evaluation of secondary metabolites from C. sessiliflora leaves is essential to making their use feasible for obtaining antioxidant and photoprotective extracts. This study aims to optimize the extraction of phenolic compounds, flavonoids, tannins, chlorophyll α, chlorophyll β, and carotenoids, as well as evaluate the antioxidant potential, sun protection factor (SPF), and the ultraviolet region scans of the leaf extracts. Liquid chromatography with a diode array detector was used to identify chemical compounds. The extracts were evaluated using different plant-to-solvent ratios and varying ethanol concentrations in water. A correlation test was conducted between the spectrophotometric profile and the levels of phenolic compounds, flavonoids, tannins, and the antioxidant potential of C. sessiliflora leaf extracts. Results showed a positive correlation between ethanol levels and the presence of chlorophyll α, chlorophyll β, carotenoids, and flavonoids. Additionally, a correlation was found between antioxidant potential, SPF, and phenolic compound content. Statistical analyses indicate that the ethanol concentration in water is more significantly relevant than the different plant-to-solvent proportions. Gallic acid, syringic acid, catechin, epicatechin, and rutin were identified in all samples. Absorption at the 260 nm wavelength can be used for extract quality control. Regarding the monitored parameters, the best extract was obtained using 2 % leaves in 25 % ethanol in water.
Background: Despite sea lavender being a medicinal species, research on its seeds' biological properties and chemical composition is unexplored. Thus, this study evaluated the effect of different extraction solvents on the biological activities and chemical profile of greenhouse-cultivated sea lavender seeds, aiming at their potential use as a dermo-cosmetic ingredient. Therefore, ethyl acetate, acetone, ethanol, and water extracts were examined for their antioxidant activity, enzyme inhibition, photoprotection, and cytotoxicity, followed by phytochemical analysis through spectrophotometric methods, further detailed by Ultrahigh-Performance Liquid Chromatography Coupled with Electrospray Ionization Mass/Mass Spectrometry (UHPLC-Esi-MS/MS).
Results: The water extract demonstrated significant antioxidant activity, evidenced by low half maximal effective concentration (EC50) values in scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals, reducing iron and chelating copper (296, 478, 230 and 678 µg/mL, respectively). The ethanol extract was more effective in inhibiting cosmetic-related enzymes, particularly elastase and hyaluronidase (2.18 and 3.21 µg/mL, respectively). The water and acetone extracts had the highest sun protection factors (23.2 and 18.9, respectively). All the extracts had nil to weak cytotoxicity (70–120% cell viability) towards mammalian cell lines. The water extract had the highest phenolics and condensed tannins (115 and 78.30 mg/g extract, respectively), while the ethanol contained the most flavonoids (62.73 mg/g extract). UHPLC-ESI-MS/MS analysis identified ethyl gallate, myricetin, rutin, and quercetin as major components of the ethanol extract, whereas myricetin-O-rutinoside isomers are predominant in the water extract.
Conclusions: These findings highlight the potential of greenhouse-cultivated sea lavender seeds as potential dermo-cosmetic ingredients, with ethanol and water extracts demonstrating superior biological activities and chemical profiles, significantly contributing to general skin health and protection.
Purpose: This study attempted to investigate the antioxidant and anti-inflammatory effects of Echinacea angustifolia extract.Methods: For analysis of radical scavenging activities, DPPH, ABTS and FRAP were performed. To analyze antioxidant properties, in addition, polyphenol and flavonoid concentrations were measured. In cell-based assays, cytotoxicity and anti-inflammatory assays were performed, using RAW 264.7.Results: The results found the followings: DPPH and ABTS assays revealed 27.98% and 20.29% respectively in terms of antioxidant activities when compared to ascorbic acid. In the FRAP assay, E. angustifolia extract (1 mg) showed 0.412±0.013 μg of reducing power (ascorbic acid). Polyphenol and flavonoid concentrations were 104.42±3.21 mg/g and 62.86±2.26 mg/g each. In terms of cytotoxicity, more than 80% cells survived after the assays, confirming the low toxicity of E. angustifolia extract. In anti-inflammatory activities, the extract reduced the inflammatory response and, at the same time, showed 51.07±4.58% inflammation-inhibiting effects at 200 μg/mL, confirming the potential of E. angustifolia extract as an ingredient of cosmeceuticals.Conclusion: These results confirmed the potential of E. angustifolia extract as an ingredient of cosmeceuticals.
Plant secondary metabolites (SMs) are not only a useful array of natural products but also an important part of plant defense system against pathogenic attacks and environmental stresses. With remarkable biological activities, plant SMs are increasingly used as medicine ingredients and food additives for therapeutic, aromatic and culinary purposes. Various genetic, ontogenic, morphogenetic and environmental factors can influence the biosynthesis and accumulation of SMs. According to the literature reports, for example, SMs accumulation is strongly dependent on a variety of environmental factors such as light, temperature, soil water, soil fertility and salinity, and for most plants, a change in an individual factor may alter the content of SMs even if other factors remain constant. Here, we review with emphasis how each of single factors to affect the accumulation of plant secondary metabolites, and conduct a comparative analysis of relevant natural products in the stressed and unstressed plants. Expectantly, this documentary review will outline a general picture of environmental factors responsible for fluctuation in plant SMs, provide a practical way to obtain consistent quality and high quantity of bioactive compounds in vegetation, and present some suggestions for future research and development.
Flavonoids, a group of natural substances with variable phenolic structures, are found in fruits, vegetables, grains, bark, roots, stems, flowers, tea and wine. These natural products are well known for their beneficial effects on health and efforts are being made to isolate the ingredients so called flavonoids. Flavonoids are now considered as an indispensable component in a variety of nutraceutical, pharmaceutical, medicinal and cosmetic applications. This is attributed to their anti-oxidative, anti-inflammatory, anti-mutagenic and anti-carcinogenic properties coupled with their capacity to modulate key cellular enzyme function. Research on flavonoids received an added impulse with the discovery of the low cardiovascular mortality rate and also prevention of CHD. Information on the working mechanisms of flavonoids is still not understood properly. However, it has widely been known for centuries that derivatives of plant origin possess a broad spectrum of biological activity. Current trends of research and development activities on flavonoids relate to isolation, identification, characterisation and functions of flavonoids and finally their applications on health benefits. Molecular docking and knowledge of bioinformatics are also being used to predict potential applications and manufacturing by industry. In the present review, attempts have been made to discuss the current trends of research and development on flavonoids, working mechanisms of flavonoids, flavonoid functions and applications, prediction of flavonoids as potential drugs in preventing chronic diseases and future research directions.
Flavonoids play an important role in the treatment of various diseases, as they are able to inhibit reactive oxygen species, which cause damage to cells and tissues which may lead to increased risk of inflammatory diseases. Baicalin and baicalein, two flavonoids found in the roots of
Scutellaria baicalensis
, in the leaves of
Thymus vulgaris
and
Oroxylum indicum
, were tested for their anti-inflammatory activity as well as for their cytotoxicity. Thereby the two compounds were investigated on Src tyrosine kinase inhibition and inhibition of production of interleukin (IL-6) in lipopolysaccharide- (LPS-) stimulated THP-1 cells. Additionally, the THP-1 cell line was used for the determination of the cytotoxicity. Both baicalin and baicalein showed some anti-inflammatory properties, while baicalein turned out to be the more active compound with higher inhibitory activities on both Src tyrosine kinase and production of cytokine IL-6. Baicalin and baicalein showed no signs of cytotoxicity in the MTS cytotoxicity assay in THP-1 cells.
Matrix metalloproteinases (MMPs) are a family of structurally and functionally related zinc-dependent enzymes responsible for proteolytic degradation of extracellular matrix components such as base membrane or interstitial stroma. MMPs play an important role in a variety of physiological and pathological tissue remodeling processes, including wound healing, embryo implantation, tumor invasion and metastasis. Since MMP-9 (gelatinase B) has unique ability to cleave type IV collagen, gene expression of MMP-9 has been focused on as a pharmacological target. Flavonoids are a class of compounds that are widely spread in plants. In the coures of screening for the suppressors of MMP-9 gene expression from natural products, Metasequoia glyptostroboides was selected. Six flavonoids, sciadopitysin, isoginkgetin, bilobetin, 2,3-dihydrohinokiflavone, luteolin and apigenin were purified as suppressors of MMP-9 gene expression from M. glyptostroboides. The suppressing activity of the isolated flavinoids on the MMP-9 gene expression was measured by gelatin zymography and Nothern blot analysis.
There has been increasing interest in the research on flavonoids from plant sources because of their versatile health benefits reported in various epidemiological studies. Since flavonoids are directly associated with human dietary ingredients and health, there is need to evaluate structure and function relationship. The bioavailability, metabolism, and biological activity of flavonoids depend upon the configuration, total number of hydroxyl groups, and substitution of functional groups about their nuclear structure. Fruits and vegetables are the main dietary sources of flavonoids for humans, along with tea and wine. Most recent researches have focused on the health aspects of flavonoids for humans. Many flavonoids are shown to have antioxidative activity, free radical scavenging capacity, coronary heart disease prevention, hepatoprotective, anti-inflammatory, and anticancer activities, while some flavonoids exhibit potential antiviral activities. In plant systems, flavonoids help in combating oxidative stress and act as growth regulators. For pharmaceutical purposes cost-effective bulk production of different types of flavonoids has been made possible with the help of microbial biotechnology. This review highlights the structural features of flavonoids, their beneficial roles in human health, and significance in plants as well as their microbial production.
The half maximal inhibitory concentration (IC50) values and trolox equivalent antioxidant capacity (TEAC) values were calculated by a 2,2′-diphenylpicrylhydrazyl (DPPH) assay and a 2,2′-azino-bis-3- ethylbenzothiazoline-6-sulfonic acid (ABTS+) assay, in order to determine the antioxidative activities of the compounds. On the basis of the DPPH assay, quercetin had the strongest antioxidative potential of the flavonoids, followed in order by fisetin, 7,8-dihydroxyflavone, morin and kaempferol. Quercetin, fisetin and 7,8-dihydroxyflavone had higher antioxidant potentials than butyl hydroxyl anisole. Quercetin had the highest TEAC value amongst the flavonoids and isoflavonoids, followed in order by 3-hydroxyflavone, fisetin, 7,8-dihydroxyflavone and morin. Comparatively, isoflavonoids were found to have significantly weaker antioxidative potential than the flavonoids.
Baicalein, a bioactive flavonoid, has poor water solubility, thereby limiting its use in a wide range of biological applications. In the present study, we used inclusion complexes of cysteinyl β‐cyclodextrin (β‐CD) with baicalein to enhance the stability and solubility of baicalein in aqueous solution. We examined the effects of inclusion complexes of cysteinyl β‐CD on collagen synthesis following ultraviolet (UV) irradiation, as well as the mechanisms underlying its effects. Our findings demonstrated that baicalein significantly restored collagen synthesis in the UV‐exposed human fibroblast Hs68 cells. In addition, synthetic cysteine functionalized β‐CDs were found to promote baicalein‐induced collagen synthesis. Inclusion complexes of cysteinyl β‐CDs with baicalein significantly upregulated the protein expression of type I collagen and activated the transcription of type I, II, and III collagen. Inclusion complexes of cysteinyl β‐CDs with baicalein also downregulated matrix metalloproteinase ‐1 and ‐3, and α‐smooth muscle actin expression. In addition, inclusion complexes of cysteinyl β‐CDs with baicalein attenuated the expression of caveolin‐1, but this treatment enhanced the UV‐induced phosphorylation of Smad in the transforming growth factor‐β pathway. These results suggested that the newly synthesized derivative of CD can be used as a complexing agent to enhance the bioavailability of flavonoids such as baicalein, especially in restoring collagen synthesis.
Activated β-catenin/T-cell factor signaling has been shown to be involved in human carcinogenesis. Here, the inhibitory effects of various synthetic naphthoflavones and napthochalcones on β-catenin/Tcf signaling in β-catenin overexpressing-cells were investigated and compared. The naphthoflavones with a β-angular pattern (5,6-benzoflavone series) resulted in a more potent inhibitory activity than those with an α-angular pattern (7,8-benzoflavone series), indicating that the direction of the naphthyl ring is an important determinant of inhibitory activity. This result is in accordance with the napthochalcone derivatives. Moreover, in silico docking results supported our in vitro biological results.
Two flavonoids, 7-O-methyl-3`,4`-didehydroxy quercetin (MDQ) and quercetin, isolated from Chinese propolis, which is the generic name for the resinous substance collected by honeybees from various plant sources, were tested for their antioxidant activity and protective effect against radiation-induced DNA damage in mouse lymphocytes. In antioxidant test, both compounds provided a dose-dependent scavenging effect on DPPH radical and a dose-dependent inhibitory effect on lipid peroxidation in mouse liver. Quercetin showed stronger scavenging and inhibitory effect than MDQ, and it also provided strong inhibition on superoxide anion radical generated in xanthine-xanthine oxidase system, but there was no inhibitory ability for MDQ. In comet assay using single cell gel electrophoresis, MDQ and quercetin showed a protective effect against DNA damage caused by gamma irradiation. They reduced DNA damage to 54% (pmol, respectively. These results suggest that free radical scavenging seems to be associated with their catechol form on the B ring, and radioprotection appears to be a likely mechanism of antioxidant activity by these flavonoids.
Apigenin (4',5,7-trihydroxyflavone) is a flavone that has been reported to have anti-inflammatory, antioxidant and anti-carcinogenic properties. In this study, we investigated the protective effects of apigenin on skin and found that, in experiments using cells, apigenin restored the viability of normal human dermal fibroblasts (nHDFs), which had been decreased by exposure to ultraviolet (UV) radiation in the UVA range. Using a senescence-associated (SA)-β-gal assay, we also demonstrate that apigenin protects against the UVA-induced senescence of nHDFs. Furthermore, we found that apigenin decreased the expression of the collagenase, matrix metalloproteinase (MMP)-1, in UVA-irradiated nHDFs. UVA, which has been previously identified as a photoaging-inducing factor, has been shown to induce MMP-1 expression. The elevated expression of MMP-1 impairs the collagen matrix, leading to the loss of elasticity and skin dryness. Therefore, we examined the clinical efficacy of apigenin on aged skin, using an apigenin‑containing cream for clinical application. Specifically, we measured dermal density, skin elasticity and the length of fine wrinkles in subjects treated with apigenin cream or the control cream without apigenin. Additionally, we investigated the effects of the apigenin-containing cream on skin texture, moisture and transepidermal water loss (TEWL). From these experiments, we found that the apigenin‑containing cream increased dermal density and elasticity, and reduced fine wrinkle length. It also improved skin evenness, moisture content and TEWL. These results clearly demonstrate the biological effects of apigenin, demonstrating both its cellular and clinical efficacy, and suggest that this compound holds promise as an anti-aging cosmetic ingredient.
Citrus and its peels, which are by-products from juice and/or jam processing, have long been used in Asian folk medicine. Citrus peels show an abundant variety of flavanones, and these flavanones have glycone and aglycone forms. Aglycones are more potent than glycones with a variety of physiological functions since aglycone absorption is more efficient than glycones. Bioconversion with cytolase converted narirutin and naringin into naringenin and hesperidin into hesperetin. Therefore, this study aimed to investigate the anti-oxidant and anti-inflammatory effects of bioconversion of Citrus unshiu (CU) peel extracts with cytolase (CU-C) in RAW264.7 cells. HPLC chromatograms showed that CU and CU-C had 23.42% and 29.39% total flavonoids, respectively. There was substantial bioconversion of narirutin to naringenin and of hesperidin to hesperetin. All citrus peel extracts showed DPPH scavenging activities in a dose-dependent manner, and CU-C was more potent than intact CU. RAW264.7 cells were pre-treated with 0∼500 μg/mL of citrus peel extracts for 4 h and then stimulated by 1 μg/mL of lipopolysaccharide (LPS) for 8 h. All citrus peel extracts showed decreased mRNA levels and protein expression of LPS-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in a dose-dependent manner. Especially, CU-C markedly inhibited mRNA and protein expression of iNOS and COX-2 compared to intact citrus peel extracts. All citrus peel extracts showed decreased NO production by iNOS activity. This result suggests that bioconversion of citrus peel extracts with cytolase may provide potent functional food materials for prevention of chronic diseases attributable to oxidation and inflammation by boosting the anti-inflammatory effects of citrus peels. © 2015, Korean Society of Food Science and Nutrition. All rights reserved.
Long-term exposure to ultraviolet irradiation from sunlight causes premature skin aging (photoaging), characterized in part by wrinkles, altered pigmentation, and loss of skin tone. Photoaged skin displays prominent alterations in the collagenous extracellular matrix of connective tissue. We investigated the role of matrix-degrading metalloproteinases, a family of proteolytic enzymes, as mediators of collagen damage in photoaging.
We studied 59 whites (33 men and 26 women, ranging in age from 21 to 58 years) with light-to-moderate skin pigmentation, none of whom had current or prior skin disease. Only some of the participants were included in each of the studies. We irradiated their buttock skin with fluorescent ultraviolet lights under standard conditions and obtained skin samples from irradiated and nonirradiated areas by keratome or punch biopsy. In some studies, tretinoin and its vehicle were applied to skin under occlusion 48 hours before ultraviolet irradiation. The expression of matrix metalloproteinases was determined by in situ hybridization, immunohistology, and in situ zymography. Irradiation-induced degradation of skin collagen was measured by radioimmunoassay of soluble cross-linked telopeptides. The protein level of tissue inhibitor of matrix metalloproteinases type 1 was determined by Western blot analysis.
A single exposure to ultraviolet irradiation increased the expression of three matrix metalloproteinases -- collagenase, a 92-kd gelatinase, and stromelysin -- in skin connective tissue and outer skin layers, as compared with nonirradiated skin. The degradation of endogenous type I collagen fibrils was increased by 58 percent in irradiated skin, as compared with nonirradiated skin. Collagenase and gelatinase activity remained maximally elevated (4.4 and 2.3 times, respectively) for seven days with four exposures to ultraviolet irradiation, delivered at two-day intervals, as compared with base-line levels. Pretreatment of skin with tretinoin (all-trans-retinoic acid) inhibited the induction of matrix metalloproteinase proteins and activity (by 70 to 80 percent) in both connective tissue and outer layers of irradiated skin. Ultraviolet irradiation also induced tissue inhibitor of matrix metalloproteinases-1, which regulates the enzyme. Induction of the inhibitor was not affected by tretinoin.
Multiple exposures to ultraviolet irradiation lead to sustained elevations of matrix metalloproteinases that degrade skin collagen and may contribute to photoaging. Treatment with topical tretinoin inhibits irradiation-induced matrix metalloproteinases but not their endogenous inhibitor.
Polyphenols constitute one of the most numerous and ubiquitous groups of plant metabolites and are an integral part of both human and animal diets. Ranging from simple phenolic molecules to highly polymerized compounds with molecular weights of greater than 30,000 Da, the occurrence of this complex group of substances in plant foods is extremely variable. Polyphenols traditionally have been considered antinutrients by animal nutritionists, because of the adverse effect of tannins, one type of polyphenol, on protein digestibility. However, recent interest in food phenolics has increased greatly, owing to their antioxidant capacity (free radical scavenging and metal chelating activities) and their possible beneficial implications in human health, such as in the treatment and prevention of cancer, cardiovascular disease, and other pathologies. Much of the literature refers to a single group of plant phenolics, the flavonoids. This review offers an overview of the nutritional effects of the main groups of polyphenolic compounds, including their metabolism, effects on nutrient bioavailability, and antioxidant activity, as well as a brief description of the chemistry of polyphenols and their occurrence in plant foods.
The B-ring substitution pattern of flavonols is a significant structural feature for their function as free radical scavengers and antioxidants. In this paper, four differently substituted B-ring hydroxylation flavonols (galangin, kaempferol, quercetin, and myricetin) and a flavonol glycoside (quercitrin) were studied for their ability to bind BSA by quenching the protein intrinsic fluorescence. From the spectra obtained, the biomolecular quenching constants, the apparent static binding constants, and the binding site values were calculated. The B-ring hydroxylation of flavonols significantly affected the binding/quenching process; in general, the binding affinity increased with the number of hydroxyl groups on the B-ring. The binding constants ( Ka) were determined as myricetin (4.90 x 10(8) L/mol) > quercetin (3.65 x 10(7) L/mol) > kaempferol (2.57 x 10(6) L/mol) > galangin (6.43 x 10(5) L/mol). The glycoside substitute at the C-ring position decreased the binding affinity. The chromatographic retention factor ( K') and logarithms of apparent partition coefficient (log Kow) were linear to the logarithms of apparent binding constants (log Ka) for flavonols with increasing hydroxyl groups on the B-ring. These results showed that the hydrogen bond force play an important role in binding flavonols to BSA. These results are also in agreement with the generally accepted structure-dependent free radical scavenger and antioxidant abilities of flavonols.