Glycosides are organic compounds consisting of a sugar (glycone) linked to a non-sugar molecule (aglycone), which can be a phenolic, steroidal, or terpenoid compound. They are naturally found in many plants, where they serve protective and energy storage functions. In cosmetics, glycosides are valued for their conditioning, antioxidant, and moisturizing properties. They are used in a wide range of products to improve skin texture and promote overall skin health.

Chemical Composition and Structure

Glycosides are composed of a sugar molecule, such as glucose or fructose, attached to an aglycone component, which may include flavonoids, terpenes, or other bioactive compounds. This structure gives glycosides a variety of biochemical properties that make them useful in both cosmetic and pharmaceutical applications.

Physical Properties

Glycosides typically appear as water-soluble powders or liquids and are often clear or slightly opaque. Due to their solubility, they are easy to incorporate into products like serums, lotions, creams, and shampoos, where they provide conditioning and moisturizing effects.

Production Process

Glycosides are typically extracted from plants through aqueous or solvent extraction processes. Some glycosides can also be synthesized chemically to ensure purity and consistency. The extraction process preserves the bioactive properties of glycosides, ensuring their effectiveness in cosmetic formulations.

• Extraction from Plant Sources: Glycosides can be extracted from various plant sources, such as fruits, leaves, and roots. The plants are harvested and cleaned to remove impurities and residues.

• Maceration: The plant parts containing the glycosides are macerated in an appropriate solvent (such as water or alcohol) to release the active compounds. This process may include the use of heat to facilitate extraction.

• Filtration: After maceration, the mixture is filtered to remove solids and plant residues, resulting in a liquid extract containing the glycosides.

• Purification: The extract may be further purified using techniques such as chromatography to isolate pure glycosides and remove other unwanted substances.

• Quality Control and Packaging: Finally, glycosides undergo quality control checks to verify their purity and composition. After analysis, they are packaged in appropriate containers for distribution and use in cosmetic products and dietary supplements.

Some medical functions of glycosides:

1. Cardiotonic Glycosides:

• Example: Digoxin, Digitoxin (from the foxglove plant).

• Function: Cardiotonic glycosides are primarily used to treat heart conditions such as congestive heart failure and certain types of arrhythmias. They work by increasing the force of heart muscle contractions, leading to improved heart efficiency and output.

2. Anti-inflammatory Properties:

• Example: Salicin (from willow bark).

• Function: Glycosides with salicylic acid derivatives have anti-inflammatory properties. Salicin, for instance, is metabolized into salicylic acid in the body and has been traditionally used to reduce fever, pain, and inflammation. It serves as a precursor to aspirin.

3. Antimicrobial and Antifungal Activity:

• Example: Saponins (from various plants).

• Function: Certain glycosides, such as saponins, have antimicrobial and antifungal properties. They disrupt the integrity of microbial cell membranes, making them useful for treating infections or as preservatives in various pharmaceutical formulations.

4. Anticancer Activity:

• Example: Podophyllotoxin glycosides (from the Podophyllum plant).

• Function: Some glycosides exhibit anticancer properties by interfering with cancer cell division. For example, derivatives of podophyllotoxin are used in chemotherapy as they inhibit topoisomerase enzymes, which are essential for DNA replication in cancer cells.

5. Laxative Effect:

• Example: Anthraquinone glycosides (from senna and aloe).

• Function: Glycosides like anthraquinones have a laxative effect and are used to treat constipation. They stimulate the bowel muscles and promote the movement of stool through the digestive tract.

6. Hypoglycemic Activity:

• Example: Glycyrrhizin (from licorice root).

• Function: Some glycosides, such as glycyrrhizin, have been shown to have hypoglycemic effects, which can help in the management of diabetes by lowering blood glucose levels.

7. Immune-modulatory Effects:

• Example: Glycosides from Echinacea species.

• Function: Certain glycosides are believed to boost the immune system. Echinacea, for example, is rich in glycosides that may stimulate the body's natural immune responses and is commonly used in remedies for colds and flu.

8. Anti-malarial Properties:

• Example: Quinine glycosides (from the cinchona tree).

• Function: Quinine, a glycoside from the bark of the cinchona tree, has historically been used to treat malaria by interfering with the ability of the malaria parasite to digest hemoglobin in the blood.

9. Diuretic Properties:

• Example: Glycosides from certain plant species like digitalis.

• Function: Some glycosides promote diuresis (increased urine production), which can be useful in treating conditions like hypertension and fluid retention.

Applications

• Antioxidant Products: Glycosides have antioxidant properties that protect the skin from oxidative damage caused by free radicals, helping to prevent premature aging.

• Skin Conditioning: Used in skincare products, glycosides enhance skin texture, making it softer and smoother, with hydrating and soothing effects.

• Cleansing Products: Some glycosides, such as alkyl glycosides, are used as gentle surfactants in shampoos and cleansers, due to their ability to cleanse without irritating the skin or hair.

Health and Safety Considerations

Safety in Use
Glycosides are generally considered safe for use in cosmetic products and are well-tolerated by the skin. However, as with any ingredient, a patch test is recommended before use, especially on sensitive skin.

Allergic Reactions
Allergic reactions to glycosides are rare, but may occur in individuals sensitive to specific plant extracts. It is always advisable to test the product on a small area of skin before use.

Toxicity and Carcinogenicity
There is no evidence to suggest that glycosides are toxic or carcinogenic. They are considered safe for topical use in cosmetics and personal care products.

Environmental Considerations
Glycosides are extracted from renewable natural sources, primarily plants. Their extraction process is relatively sustainable and low-impact, making them an eco-friendly choice for cosmetic formulations.

Regulatory Status
Glycosides are approved for use in cosmetics by major regulatory authorities, including the European Union and the FDA in the United States.

References__________________________________________________________________________

Khan, H., Saeedi, M., Nabavi, S. M., Mubarak, M. S., & Bishayee, A. (2019). Glycosides from medicinal plants as potential anticancer agents: emerging trends towards future drugs. Current medicinal chemistry, 26(13), 2389-2406.

Abstract. Background: Cancer continues to be a global burden, despite the advancement of various technological and pharmaceutical improvements over the past two decades. Methods for treating cancer include surgery, radiotherapy and chemotherapy in addition to other specialized techniques. On the other hand, medicinal plants have been traditionally employed either as the complementary medicine or dietary agents in the treatment and management of cancer. Medicinal plants are a rich source of secondary metabolites with interesting biological and pharmacological activities. Among these metabolites, glycosides are naturally occurring substances and have outstanding therapeutic potential and clinical utility. Methods: Different medical research engines such as, GoogleScholar, PubMed, SpringerLink, ScienceDirect were used to collect related literature on the subject matter. In this regard, only peer-reviewed journals were considered. Results: Emerging results showed that numerous glycosides isolated from various plants possessed marked anticancer activity against a variety of cancer cell lines. Accordingly, the aim of the present review is to shed light on the anticancer effects of glycosides, analyze possible mechanisms of action, and highlight the role of these natural agents as complementary and alternative medicine in combating and managing cancer. Conclusion: The glycosides isolated from different plants demonstrated potent cytotoxic effects against various cancer cell lines in initial preclinical studies. The anticancer effect was mediated through multiple mechanisms; however further detailed studies are needed to understand the full potential of glycosides for clinical utility.

Ganjewala, D. (2010). Advances in cyanogenic glycosides biosynthesis and analyses in plants: A review. Acta Biologica Szegediensis, 54(1), 1-14.

Abstract. A number of species of plants produce repertoire of cyanogenic glycosides via a common biosynthetic scheme. Cyanogenic glycosides play pivotal roles in organization of chemical defense system in plants and in plant–insect interactions. Several commercial crop plants such as sorghum (Sorghum bicolor), cassava (Manihot esculenta) and barley (Hordium vulgare) are cyanogenic and accumulate significant amounts of cyanogenic glycosides. The study of biosynthesis of dhurrin in sorghum has underpinned several early breakthroughs in cyanogenic glycoside researches. Despite great deal of structural diversity in cyanogenic glycosides, almost all of them are believed to be derived from only six different amino acids L-valine, L-isoleucine, L-leucine, L-phenylalanine, or L-tyrosine and cyclopentenyl-glycine (a non protein amino acid). Our knowledge about biosynthesis of cyanogenic glycosides and molecular regulatory processes underlying their biosynthesis has been increased impressively in the past few years. The rapid identification, characterization and cloning of genes encoding enzymes of the cyanogenic glycoside biosynthetic and catabolic pathways from several plants has greatly facilitated our understanding of cyanogenic glycosides biosynthesis and regulation. Today it is known that enzymes of cyanogenic glycoside biosynthetic pathway in sorghum are organized as metabolon most likely to those of other secondary metabolic pathways. Knowledge of state of art of biosynthesis and regulation of cyanogenic glycosides made possible the metabolic engineering of these pathways resulting in development of transgenics of cassava, tobacco, lotus and Arabidopsis with manipulated cyanogenic glycosides content. Simultaneously, many new developments have been witnessed in methods/techniques/ procedures for detection of cyanogenic glycosides in plant samples, foods and foodstuffs. The present review sequentially discusses all of these issues with updated information gathered from the published reports on cyanogenic glycosides.

Francisco, I. A., & Pinotti, M. H. P. (2000). Cyanogenic glycosides in plants. Brazilian Archives of Biology and Technology, 43, 487-492.

Abstracts. The presence of cyanogenic glycosides was determined in 70 plant species from the campus of the State University of Londrina, PR, Brazil, and a further 45 plant species from the Forestry Reserve on the Doralice Farm in Ibiporã, PR, Brazil. Of the vegetative species from the State University of Londrina, 7.1% showed cyanogenic glycosides: Manihot esculenta (Euphorbiaceae), Passiflora edulis (Passifloraceae), Macadamia ternifolia (Proteaceae), Prunus persica (Rosaceae) and Beloperone sp (Acanthaceae).The first four species were considered to be potentially cyanogenic in the field. From the Forestry Reserve on the Doralice Farm, the plant species with cyanogenic glycosides were: Holocalix balanseae (Caesalpinaceae), Nectranda megapotamica (Lauraceae), Trichilia casareti (Meliaceae), Trichilia elegans (Meliaceae) and Rapanea umbellata (Myrsinaceae), making 11.1% of the total species analyzed. Only Holocalix balanseae was considered to be potentially cyanogenic in the field.

Kytidou, K., Artola, M., Overkleeft, H. S., & Aerts, J. M. (2020). Plant glycosides and glycosidases: a treasure-trove for therapeutics. Frontiers in plant science, 11, 357.

Abstract. Plants contain numerous glycoconjugates that are metabolized by specific glucosyltransferases and hydrolyzed by specific glycosidases, some also catalyzing synthetic transglycosylation reactions. The documented value of plant-derived glycoconjugates to beneficially modulate metabolism is first addressed. Next, focus is given to glycosidases, the central theme of the review. The therapeutic value of plant glycosidases is discussed as well as the present production in plant platforms of therapeutic human glycosidases used in enzyme replacement therapies. The increasing knowledge on glycosidases, including structure and catalytic mechanism, is described. The novel insights have allowed the design of functionalized highly specific suicide inhibitors of glycosidases. These so-called activity-based probes allow unprecedented visualization of glycosidases cross-species. Here, special attention is paid on the use of such probes in plant science that promote the discovery of novel enzymes and the identification of potential therapeutic inhibitors and chaperones.