If you are also suffering from dandruff, dandruff is a large amount of desquamation caused by the excessive proliferation of scalp keratinocytes, which has become a common problem in modern society and is difficult to eradicate. The main cause of dandruff is the excessive proliferation of Malassezia. Malassezia produces unsaturated fatty acids by metabolizing lipids in sebum, which triggers an inflammatory response.
Traditional anti-dandruff agents have problems such as side effects, drug resistance and environmental pollution, while plant-derived anti-dandruff ingredients have the characteristics of wide source, small side effects, low price, less drug resistance, and suitable for long-term and preventive applications, which makes the research and development of plant-derived anti-dandruff products have good prospects.
1. Causes of dandruff
Dandruff is a common problem that affects about 50% of adults worldwide, and it is also more common in men than women. Dandruff begins in adolescence, peaks in incidence and severity at about 20 years of age, and becomes less prevalent in people over 50 years of age. Dandruff generally refers to the appearance of thin, flaky scales on the scalp or in the hair, often accompanied by itching.
Dandruff is a clump of exfoliated keratinocytes that maintain a large cohesion with each other and detach from the surface of the stratum corneum. The extent of dandruff is difficult to define because dandruff is not clearly defined from seborrheic dermatitis and other skin conditions that cause desquamation.
Many scholars believe that dandruff and seborrheic dermatitis are different stages of the same disease, dandruff is a mild manifestation of seborrheic dermatitis, not accompanied by atopic dermatitis, psoriasis and other skin diseases, usually in the form of smaller, dry scales, and seborrheic dermatitis is a more inflammatory disease that usually extends beyond the scalp, shedding larger, more adhesive, and greasy.
At present, the academic community believes that there are three main factors that determine the formation of dandruff: Malassezia proliferation, scalp lipid secretion, and individual susceptibility. These 3 factors are interrelated, and they determine when dandruff forms and manifests. As for the research on dandruff, most of the current research directions focus on the pathogenicity of Malassezia.
As for the question of how Malassezia causes dandruff, most scholars believe that the accumulation of unsaturated fatty acids caused by Malassezia-derived phospholipase and lipase is the key to triggering an inflammatory response.
In vitro experiments, it was proved that Malassezia furfur can produce phospholipase A2, and it is believed that Malassezia may catalyze the hydrolysis of triacylglycerol to produce arachidonic acid through phospholipase A2, and this catalytic effect may indirectly trigger inflammation through the eicosanoid pathway.
At the same time, Malassezia-derived lipase degrades triglycerides in sebum, which are hydrolyzed into unsaturated fatty acids, which trigger an inflammatory response.
2. Pathogenesis of Malassezia
Malassezia is a ubiquitous unicellular basidiomyces yeast that is a component of the fungal flora of animal and human skin that can cause opportunistic infections that cause various Malassezia skin diseases. There are currently 7 species of Malassezia in the world.
By electron microscopy, Malassezia cells have a thick, multi-layered cell wall structure composed of chitin and extremely high levels of lipids, with much higher lipid content than Candida albicans and Saccharomyces cerevisiae. Its cell surface hydrophobicity (CSH) has been implicated as a major factor in the development of drug resistance and inflammation. Malassezia proliferates in sebum-rich areas such as the scalp and other seborrheic areas.
With the exception of Malassezia pachyderma, all Malassezia require fatty acids as a carbon source to survive. Since C14 and C16 saturated fatty acids cannot be synthesized, Malassezia obtains essential lipids by hydrolyzing triglycerides in sebum by lipase and phospholipase transcribed from the Malassezia genome.
Malassezia is the only known dermatosymbiotic fungus that lacks the fatty acid synthase gene. Malassezia reproduces through unipolar budding, and the extruded bud is separated from the mother cell by a septum, forming a continuous collar-like scar.
3. Treatment of dandruff
There are three main types of anti-dandruff agents in commonly used anti-dandruff products: keratinolytics, cell growth inhibitors, and antifungal preparations. Keratin exfoliators, such as salicylic acid, sulfur, and coal tar, have a certain degree of exfoliation, but such products have a poor odor, strong irritation, and long-term use will cause damage to the stratum corneum.
Cell growth inhibitors improve keratinization and desquamation symptoms by reducing the turnover rate of stratum corneum cells, such as selenium sulfide, but it has a peculiar odor and makes the hair dry after use, which is easy to cause inflammation in people with sensitive skin.
At present, antifungal preparations are mostly added to anti-dandruff and antipruritic products. Azole fungal inhibitors inhibit the conversion of lanosterol to ergosterol by targeting the 14'-lanosterol demethylase encoded by the ERG11 gene for ergosterol biosynthesis.
The reduced ergosterol biosynthesis caused by the use of azole antifungal preparations disrupts the function of vacuolar ATPase, thereby disrupting the integrity and permeability of the cell membrane, resulting in vacuolar acidification and disruption of ionic homeostasis.
ZPT significantly increased the intracellular zinc level of Malassezia, and the increase of cellular zinc led to a significant down-regulation of SOD2 gene, thereby disrupting the synthesis of Fe-S cluster proteins and leading to mitochondrial dysfunction, thereby inducing apoptosis of Malassezia.
The existence of these problems makes the application of the above drugs limited. In recent years, with the popularity of environmental protection, low carbon, green and natural trends, plant-derived anti-dandruff products have become a hot spot in research, and have attracted more and more attention and love from people.
The characteristics of low side effects, wide range of sources, low price, and low appearance of drug resistance, and suitability for long-term and prophylactic applications make the research and development of plant-derived anti-dandruff products have good prospects.
However, due to the dark color, heavy odor and complex composition of plant extracts, and its mechanism of action is not clear, it is the direction of new drug development to use modern technology and technology to isolate effective antifungal components from natural plants and study their mechanism of action.
Fourth, plant antibacterial components and mechanism of action
Most of the secondary metabolites with antimicrobial properties belong to chemical groups, namely phenols, terpenes, alkaloids and polypeptides, which have a variety of mechanisms of action on disease-causing microorganisms. Phytochemicals with antimicrobial properties can be divided into the following four broad categories:
- Phenols, which are the most widely distributed secondary metabolites in the plant kingdom. Phenolic compounds contain one or more hydroxyl groups that are directly linked to the aromatic hydrocarbon chain, and phenolic compounds are typically classified using parameters such as chemical composition, hydroxyl number number, number of substituents on the carbon skeleton, etc.
- Terpenes, which are polymerized isoprene derivatives, the synthesis process of which is carried out through the mevalonate pathway with acetate as the starting unit. The classification of various terpenes is based on the number of isoprene units (C5) they contain. When terpenes contain some other elements, usually oxygen, they are called terpenes.
- Alkaloids, i.e., nitrogen-containing basic organic compounds. In addition to carbon, hydrogen, and nitrogen, some alkaloids may contain oxygen, sulfur, and rarely other elements such as chlorine, bromine, and phosphorus. There is no clear distinction between alkaloids and other nitrogen-containing natural substances such as amino acids, nucleotides, and amines.
- Antimicrobial peptides, plant antimicrobial peptides are a group of small molecule proteins produced by different plants that are part of their defense mechanisms. Most AMPs are polypeptides containing 10~60 amino acids, with a molecular weight range of 2~13kDa, and are usually positively charged proteins with a helical structure.
Due to the vast chemical diversity of phytochemicals, the mechanism of action of these compounds is not fully understood. On the basis of the various studies that have been conducted, it seems that different phytochemicals target different tissue levels, such as the molecular level, the cellular level, and the biofilm level.
The diversity of the mechanisms of action exhibited by phytochemicals holds promise for addressing the problem of antibiotic resistance, which often occurs in pathogens that cause infectious diseases.
At the molecular level, various antimicrobial phytochemicals react with different biomolecules present at the site of action, chemically and physically modifying them, causing them to partially or completely lose their biological function. During such reactions, phytochemicals or their bioactive products bind to various biomolecules, such as proteins and nucleic acids, through covalent or non-covalent bonds.
These reactive compounds contain some very reactive groups such as aldehyde and sulfhydryl groups, epoxides, double bonds with an alkene bond configuration and triple bonds in their structure that can form covalent bonds with the DNA of proteins and microorganisms.
Proteins are the functional units of cells and play important roles in cells, such as enzymes, receptors, transcription factors, ion channel transporters, or cytoskeletal proteins. Therefore, the alteration of the protein structure of cells by any antimicrobial plant compound will undoubtedly adversely affect the survival of the organism that has changed.
Similar to covalent interactions, non-covalent interactions can also alter the structure of proteins, for example, phenolic compounds containing one or more hydroxyl groups can form hydrogen bonds with electronegative atoms in proteins.
In addition, phenolic compounds can partially dissociate into negatively charged phenolic acid ions under normal physiological conditions and form ionic bonds with positively charged amino acid residues of proteins and affect the structural and functional properties of proteins.
Reactive oxygen species (ROS) are a group of highly reactive and unstable chemical forms of oxygen that can react with a range of biomolecules and, if not inhibited in the early stages of synthesis, may cause a variety of diseases and even induce apoptosis.
On the one hand, many phytochemicals, such as phenolic compounds, have the ability to reduce ROS production through their high antioxidant properties, and on the other hand, some phytochemicals induce ROS production.
It has been shown that excessive production of ROS leads to severe oxidative stress, resulting in nucleic acid damage, oxidation of polyunsaturated fatty acids in lipids, and oxidation of amino acids in proteins. Several apoptosis-inducing phytochemicals have been reported to produce large amounts of hydroxyl radicals during apoptosis.
V. Conclusion
The purpose of this study was to develop a plant-derived natural anti-dandruff component, to screen eugenol by anti-Malassezia anti-susceptibility test, and to study the antibacterial activity of eugenol combined with traditional anti-dandruff agents and the antibacterial mechanism of eugenol, eugenol has good antibacterial activity against M. furfur, and has better antibacterial effect when combined with traditional anti-dandruff agents.
In addition, eugenol has a good safety at the cellular level and in the human body, and has the potential to be used in anti-dandruff products. The bactericidal mechanism of eugenol for M. furfur involves the destruction of the cell wall and membrane structure inside the cell.
Although this paper provides a theoretical basis for the application of eugenol in anti-dandruff products, there is still a lack of product trial and efficacy evaluation, and the mechanism of action of Malassezia needs to be further studied.
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