Abstract
Saponins are natural compounds that predominate in numerous plant species and are characterized by foaming in aqueous solutions. Chemically, they are composed of a hydrophobic structure of triterpene or steroidal nature that is linked to hydrophilic sugar chains; this combination gives them the ability to interact uniquely with cell membranes and even modulate physiological processes, which provides them with versatile properties with applications as therapeutic agents for various diseases of public health importance. Given the need for safer and less invasive therapeutic approaches, the study of bioactive compounds of plant origin has gained relevance. In this context, saponins emerge as potential biopharmaceuticals, thanks to their multiple mechanisms of action and relatively low toxicity compared to synthetic drugs. This review aims to deepen the knowledge of plant-derived saponins, explore their therapeutic applications validated by in vitro and in vivo pharmacological studies, and identify the main challenges in their development as pharmaceuticals.
Introduction
Saponins constitute a class of secondary metabolites of the plant kingdom, where they play the essential role of defense agents against herbivores, pathogens, and abiotic stress. Moreover, they exhibit antifungal, antibacterial, and antiviral activity, contributing to plant survival, and modulate the rhizosphere microbiome by participating in symbiotic relationships in some legumes, which has sparked interest in phytoremediation and genetic engineering for the development of more resilient crops.1,2
Saponins have shown broad biological activities with therapeutic potential in medicine, ranging from anti-inflammatory, antitumor, antiviral, hypocholesterolemic, and immunostimulant activities. They may even participate as adjuvants in vaccines, facilitating the immunological response of the antigen without generating serious adverse effects. 3 On the other hand, they are widely used as active ingredients in cosmetic products due to their cleansing, antimicrobial, and antioxidant properties. 4 Another sector that makes vast use of saponins is the food industry, employing them as nutraceutical components and supplements; however, since they also possess hemolytic capacity, they are applied with moderation under the regulations of international organizations.5,6
From the point of view of scientific research, saponins are models for studying membrane-compound interactions due to their affinity for cholesterol and their ability to alter cell permeability. 7 Likewise, the structure of saponins allows a versatile range of chemical modifications, favoring the development of derivatives for pharmacological, nutraceutical, and biotechnological purposes. 8 In addition, obtaining them through plant tissue culture, metabolic engineering, and bacterial biotransformation is a potential area for optimizing yields and reducing environmental impact compared to conventional extraction, which promotes industrial economy and sustainability.9,10 It should be noted that the potential of saponins is not yet fully exploited, so it is undoubtedly necessary to continue examining the different areas, plant sources, and process optimization.
Saponins and Their Classification
Saponins are molecules composed of two units: a water-soluble part called glycone (one or more sugar molecules), which is linked by a glycosidic bond to the liposoluble part commonly known as aglycone or sapogenin, which can be steroidal, triterpene or steroidal glycoalkaloids in nature.3,11–13 This duality gives them an amphiphilic character (a combination of sugar chains and sapogenin).
According to the structure of the main sapogenin ring, saponins are classified as triterpene and steroidal.9,14,15 Triterpene saponins are distributed in dicotyledonous angiosperms; their representative skeletons are of the pentacyclic oleane, ursane and lupane type, and tetracyclic damarane16–19; while steroidal ones can be tetracyclic cholestane, hexacyclic spirostane, pentacyclic furostane and lactone-containing cardenolide,14,20–23 and are mainly reported in monocotyledonous angiosperm species. Depending on the carbohydrate, saponins can be classified according to the number of sugar residues connected. They are called mono, di, or tridesmosidic (if they have one, two, or three sugar residues). In steroidal saponins, the sugar molecules are usually connected to carbons 3 and 26, while in triterpenic saponins, the sugars are linked to carbons 3 and 28.24,25
Because of the above, there are numerous possibilities of combinations in the aglycone (Figure 1) with sugars, such as glucose, galactose, 6-deoxyhexoses (rhamnose), arabinose, xylose, glucuronic acid, and glucosamine.26,27 Sapogenin and sugar combinations give rise to a considerable variety of saponins. This vast group of compounds is abundant in numerous species; it is even common to find more than one type of saponin in the same species.24,28 More than 200 steroidal saponins are known, reported mainly in cotyledonous species, while triterpene saponins are reported in dicotyledons.29–33

Composition of saponins (oleananes, lupanes, ursanes, dammarans), the steroidal saponins (furostanes, cardenolides, cholestanes, spirostans), and the steroidal glycoalkaloids (solanidanes and spirosolane).
Functions of Saponins in Plants
Plants cannot move, fluidity to move or any ability that allows them to take refuge when they are exposed to environmental situations, attack by herbivores, or any cause that compromises their survival,34,35 they have developed, through secondary metabolism, the ability to biosynthesize compounds that allow them to defend themselves from all situations that pose a risk to them,16,36 in the face of each type of attack, the plant has developed a defense mechanism.37,38 Pathogens and herbivores can enter plants through stomata or by penetrating the cell wall. In response, neighboring cells activate defense mechanisms that depend on the plant's ability to recognize the pathogen through specific molecular patterns. This recognition is mediated by transmembrane domain proteins that trigger kinase cascades and induce both constitutive and induced defense responses.39–42
The constitutive system, active throughout the entire cell cycle, protects the plant from pathogens without requiring additional energy expenditure.43–45 This mechanism includes physical barriers—such as cell walls, cuticles, bark, trichomes, and spines—and chemical barriers composed of compounds that deter predators, including saponins, cyanogenic glycosides, and cyclic hydroxamic acids.42,46,47
The induced system, in turn, produces chemical compounds derived from secondary metabolism.38,48 This system is activated in cells located in areas affected by pathogens or abiotic stress, such as water, light, or nutrient deficiency or excess. Depending on the stimulus perceived, it triggers the biosynthesis of chemical compounds that contribute to plant defense.40,49 Among the metabolites synthesized in response to pathogen attack, saponins are particularly notable, accumulating in seeds, stems, fruits, and roots.3,32,33
The literature reports that saponins can permeate cells due to their liposoluble nature through aglycone, managing to anchor themselves to the cell membrane; at the same time, their sugar diffuses into the cell, causing an increase in osmotic pressure to the point of lysing the cell of the pathogen.50–52 With this mechanism, saponins protect plants from predators. However, research into plant defense mechanisms using saponins is still underway.
More than 200 steroidal saponins are reported in cotyledons’ species, while triterpene saponins are reported in dicotyledons. Their function has been associated with defense against pathogens and herbivores, and they can be found in seeds, fruits, leaves, stems, and roots.3,53
Properties of Saponins
The word saponin comes from the Latin “sapo” and means soap; this name was coined due to its ability to generate foam when it meets water.5,54 The foam formed is a consequence of the reduction of the force of attraction between the molecules; the saponin substance is located at the interface of the fluid as occurs with water and oil or air and water.2,55 This property is called “surfactant,” that is, they disperse one liquid in another, avoiding the immiscible character, which in turn gives them the moisturizing capacity.8,56,57 Also, their amphiphilic property allows them to form micelles, which facilitate cleaning when used as soaps.58,59
They are therefore considered natural surfactants with applications in the formation of emulsions and foams, and they are the replacement for synthetic surfactants since they are obtained from natural renewable sources.8,55,60,61 Some even comply with regulatory specifications such as the United States Food and Drug Administration (FDA), which has granted them the “Generally Recognized as Safe” (GRAS) recognition, and the Codex Alimentarius has approved their use as a food additive.5,62,63
Another important property of saponins is hemolytic (destruction of red blood cells in a short period). Although it has been studied for years, the most accepted theory reports that the cell membrane is penetrated by saponin (Figure 2) because the aglycone is similar to the cholesterol in the membrane and eliminates it leaving pores permeable to the cytosol,64,65 this action causes an increase in the fluidity of the membrane and its permanent permeability to large molecules, which consequently allows hemolytic action.54,66,67 Other authors argue that hemolytic activity is related to specific receptors.65,68,69 Regardless of the theory, saponins exhibit this effect even if evaluated at the extract level.

Cell membrane structure. a) ordinary cell membrane, b) cell membrane after interacting with saponins.
Key Findings
This review highlights the medical applications of saponins. Google Scholar, PubMed, Scie Finder, and Elsevier databases were consulted to do so. The search words were “saponins,” “triterpene saponins,” “steroidal saponins,” “anti-inflammatory saponins,” “cytotoxic saponins,” and “antimicrobial saponins.” Articles, reviews, and mini reviews were selected and organized in a database, and those lacking clear information were excluded.
Potential Therapeutic of Saponins
Saponins exhibit a broad spectrum of therapeutic properties, positioning them as promising candidates for drug development. Numerous studies have highlighted their potential in anticancer, antimicrobial, antiviral, anti-inflammatory, and hepatoprotective therapies, among others.30,31,70
Antiproliferative Activity of Cancer Cells
Cancer remains one of the leading causes of death globally, and chemotherapy is a primary treatment for its prevention and control. Natural products, known for their remarkable chemical diversity, continue to be extensively studied for their anticancer potential. Among these, saponins isolated from various plant species have shown significant cytotoxic effects.
71
For instance, soyasaponins key bioactive compounds in Glycine max (soybean), have demonstrated promising anticancer properties. An extract containing the majority of soybean saponins I (62%) and III (29%), was found to inhibit the growth of Hep-G2 cancer cells.72,73 Another study revealed that soyasaponin I (

Saponins with therapeutic potential (Antiproliferative activity of cancer cells).
Saponins with Antiproliferative Activity of Cancer Cells.
Anti-Inflammatory Activity
Inflammation is a complex biological response to harmful stimuli such as pathogens, damaged cells, or irritants. 85 However, when inflammation becomes uncontrolled, it can lead to significant tissue and organ damage. Therefore, it is valuable to discover anti-inflammatory agents from natural sources. 86
Among these natural compounds, soyasaponin A1 (

Saponins with therapeutic potential (Anti-inflammatory activity).
Saponins with Anti-Inflammatory Activity.
Antimicrobial Activity
Infectious diseases have profoundly influenced the course of human history. Infection is defined as the multiplication of microbes in the tissues of the host. These microorganisms include bacteria, viruses, fungi, and protozoa. Antimicrobial activity refers to the ability of a substance or drug to inhibit or kill the growth and reproduction of such microorganisms.94,95
Among these, fungal infections are common in immunosuppressed patients, and overcoming these diseases is often a prolonged process due to the limited availability of antifungal drugs. Consequently, there is an urgent and essential need to develop antifungal agents that are non-toxic, biocompatible, and environmentally friendly.
96
Monodesmosidic triterpenoid saponins, phytolaccoside B (
On another point, viruses are among the leading pathogenic agents responsible for numerous serious diseases in humans, animals, and plants. In the search for new antivirals, some saponins have been of great interest. In vivo studies have shown that oral administration of ginsenoside Rb2 (
Antibiotic resistance has become a serious concern due to antibiotic overuse, making the development of new antimicrobial agents essential.
21
Several studies have identified various saponins of plant origin with remarkable antibacterial efficacy. Fruticoside I (

Saponins with therapeutic potential (Antimicrobial activity).
Saponins with Antimicrobial Activity.
Other Therapeutic Potentials and Uses of Saponins
Beyond the therapeutic properties previously described, several studies have also highlighted the potential of saponins in other biomedical applications. For instance, triterpenoid saponins, including escin (

Saponins with therapeutic potential (Other Therapeutic Potentials of Saponins).
Saponins with Other Therapeutic Potentials.
On the other hand, food technology takes advantage of its antimicrobial properties, while the cosmetic and pharmaceutical industry exploits its emulsifying and foaming properties with moisturizing and cleaning capacity.1,5 These novel applications position saponins as molecules that replace synthetic surfactants; even the FDA suggests their use as an additive in foods and beverages, likewise the FAO, through the Codex Alimentarius, establishes the consumption limits of plant extracts rich in saponins.60,115–117
Perspectives
Saponins constitute a group of compounds with extremely versatile therapeutic applications; however, their clinical implementation faces significant challenges, including their low bioavailability, hemolytic activity at high doses, and limited standardization of plant extracts. Given these limitations, the development of innovative technologies such as encapsulation, semisynthetic synthesis, and clinical studies is essential to realize their pharmacological potential.
Furthermore, saponin's structural complexity and composition variability among different plant species complicate their standardization and large-scale synthesis. In this context, a multidisciplinary approach integrating phytochemistry, pharmacology, molecular biology, and nanotechnology is necessary to deepen our understanding of their composition, mechanisms of action, toxicity, and biopharmaceutical behavior.
Furthermore, using sustainable technologies, such as plant tissue cultures using plant biotechnology and metabolic engineering tools, represents a viable strategy for the controlled and sustainable scaling of these metabolites. Added to this effort are omics techniques—such as metabolomics and transcriptomics—that provide valuable information on the biosynthetic pathways involved and allow for the selection of species or genotypes with optimized saponin production profiles.
Recently, saponins have shown a propensity to form nanoemulsions, improving their stability and reducing toxicity at high concentrations. Some reports even indicate that they are potential substitutes for synthetic surfactants such as Tween 80. This application is crucial in the food industry, allowing for extended shelf life and the incorporation of bioactive lipid compounds. Furthermore, due to their immunoadjuvant capacity, saponins are being encapsulated and used in some vaccines, enhancing immunity while avoiding the toxic effects of free saponins. Additionally, saponins are integrated into formulations as biostimulants, improving the dispersion and wetting of agricultural products. This, in turn, promotes the absorption of active ingredients by plants by reducing surface tension.
Finally, controlled clinical trials with purified saponins are essential to overcome the obstacle posed by their hemolytic activity and move toward regulatory approval. Most available studies have been limited to in vitro research or animal models, restricting their direct clinical applicability.
In conclusion, these key aspects constitute strong arguments for continuing and intensifying the study of saponins from diverse perspectives to consolidate their use as effective and safe therapeutic agents.
Conclusion
Saponins are consolidating their position as secondary metabolites of immense strategic value, thanks to their proven biological and amphipathic multifunctionality. This versatility establishes them as a fundamental pillar for both the development of innovative therapeutic solutions and the transition to a sustainable bioeconomy. The therapeutic relevance of saponins in human health is undeniable, given their broad spectrum of biological activities, which make them promising candidates for the design of treatments for complex diseases, including cancer, infections, and metabolic disorders. To fully realize this potential, nanotechnology is indispensable. Optimizing nanoformulations overcomes the challenges of bioavailability and toxicity, enabling controlled, targeted release of active compounds.
Additionally, saponins extend their usefulness to the sustainable industry. Their capacity as natural surfactants confers a significant environmental advantage, facilitating the replacement of synthetic and aggressive components in sectors such as food, agriculture (as biostimulants), and detergents. In short, the successful and safe integration of saponins into the market requires ongoing interdisciplinary research. This effort must focus on the systematic study of their vast structural diversity and the clinical validation of nanoformulations. Because saponins are obtained sustainably and utilize plant byproducts, they represent not only a fertile field for scientific advancement but also a strategic opportunity to develop safer therapies and more environmentally friendly industrial processes.
Footnotes
Acknowledgments
We thank the Director of the National Polytechnic Institute (IPN, Mexico), the Rector General of the Metropolitan Autonomous University (UAM, Mexico), and the Rector of the Autonomous University of the State of Mexico (UAEMex, Mexico) for their support in developing applied research, technological development, and social impact activities.
Authors’ Contributions
Mariana Sánchez-Ramos, Araceli Guerrero-Alonso: Conceptualization; Francisco Cruz-Sosa, Juan Orozco-Villafuerte: Funding acquisition; Mariana Sánchez-Ramos, Araceli Guerrero-Alonso: Writing-original draft: Leticia Buendía-González, Carmen Hernández-Jaimes: Data curation; Mariana Sánchez-Ramos, Francisco Cruz-Sosa: Writing-review & editing, Angélica Román-Guerrero: Supervision; Mariana Sánchez-Ramos, Francisco Cruz-Sosa: Revision.
Funding
The authors declared having received financial support for the preparation of this review article: This work was funded through the research project “Development of new vaccine adjuvants from medicinal plant saponins, towards sovereignty in the coverage of the national vaccination scheme. Area: Public Health. within the framework of Consortia of the Call for inter-institutional collaboration projects in the State of Mexico IPN-UAM-UAEMex. Grant award numbers SIP-CC-002-2024, PE012, 7157/2024ECON
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
