1Associate Professor and Head, Department of Botany, Shikshan Maharshi Guruvarya R. G. Shinde Mahavidyalaya, Paranda Dist. Dharashiv (Osmanabad) 413 502, (M.S.) India.
2Assistant Professor, Department of Botany, Shriman Bhausaheb Zadbuke Mahavidyalaya, Barshi Tal. Barshi, Dist.- Solapur 413 401 Maharashtra (India).
3Faculty of Pharmaceutical Sciences, Amrapali University, Haldwani, Uttarakhand, India.
4Assistant professor, Department of Microbiology, Sri Bharathi Arts and science college for women, Kaikkurichi, Pudukkottai, India.
5Assistant Professor, Department of Microbiology, Sri Bharathi Arts and Science College for Women, Kaikkuruchi Pudukkottai, India.
6Assistant Professor, Arputha college of arts and science, Vamban, India.
Viola odorata Linn., commonly referred to as Sweet Violet, is an herb with a very rich ethnomedicinal tradition as it is extensively used in Ayurveda, Unani, Traditional Persian Medicine and European folk medicine. V. odorata has been used traditionally as a treatment agent to treat respiratory diseases, skin conditions, inflammatory to conditions, febrile conditions, neurological disturbances and cardiovascular diseases. The pharmacological effect of this herb is mostly because of the diverse spectrum of phytochemicals, that include flavonoids, alkaloid, saponins, phenolic, essential oils, coumarins, mucilage, and polysaccharides. These bioactive compounds have synergetic effects that add to the antioxidant, anti-inflammatory, anti-microbial, expectorant, antitussive, analgesic, antipyretic, neuroprotective and anticancer properties of the plant. Recently, science has discovered valuable information about the pharmacodynamic effects of V. odorata its medicinal properties. Its antioxidant and anti-inflammatory properties are mainly due to flavonoids and phenolic acids, whereas saponins and mucilage are known to contribute with their properties, which is the reason why it is traditionally used in respiratory disorders. The essential oils are highly enriched with substances such as methyl salicylate and eugenol, which, in addition to the antimicrobial and analgesic activities, make the oils useful especially in treatment of diseases that are painful and infectious. New research is also indicative of the neuroprotective and cytotoxic activity of V. odorata, which makes it relevant in treatment of neurodegenerative diseases and cancer. In spite of its encouraging pharmacology together with its traditional medicinal value, there is a dearth in clinical validation thus requiring more potent in vivo research and randomized clinical trials to devise standardized therapies and product levels. Further studies are also warranted on unraveling molecular mode of action, pharmacokinetics and safety profile to sort out the gap between traditional usage and evidence based medicine. This review has been an overall summary of the phytochemistry, cultural uses and pharmacological effects of Viola odorata and therefore is the reason why it is such a good source of phytotherapeutic agents. As the world takes increased interest in herbal drugs, there is a possibility of V. odorata being developed as a drug in the future in regards to respiratory, inflammatory, infectious, neurological, and oncological treatment.expectorant and demulcent
To date, medicinal plants have constituted an essential part of healthcare since ancient times and offered solutions in the treatment of a vast number of conditions. Of these last, the Sweet Violet, or Viola odorata Linn., has been long valued not only on account of its sweet fragrance and beautiful forms, but still more as possessing some of the most important medicinal properties[1]. A member of the family Violaceae, V. odorata is a perennial herbaceous flower indigenous to Europe and some of Asia and is now cultivated and naturalized in other temperate areas in different parts of the world[2]. In different medicine systems like Ayurveda, Unani, Siddha, and western herbal medicine and culture, it has been conventionally held in regard to treating diseases that hit such parts of the body like the respiratory passage, inflammatory sicknesses, skin diseases, and nervousness disorder[3-5]. The Viola odorata has been attributed to its therapeutic potential linked to the presence of a rich reservoir of phytochemicals such as flavonoids, alkaloids, saponins, phenolic acids, coumarins, essential oils, mucilage, and anthocyanins[6]. These bioactive substances impart in the plant, an extensive list of pharmacological effects, that include the anti-inflammatory, antioxidant, antimicrobial, anticancer activity and that accomplishes the neuroprotection, the expectorant effect and analgesic effect[7]. Although pharmacologically its use in folk medicine has dated back centuries the current scientific investigation has only recently started decoding the mechanism behind its traditional uses and V. odorata should be considered as a candidate in the progressive study of the field of phytopharmaceutical design[8].
Botanical Profile and Taxonomy
Viola odorata Linn is a species which falls under the family of Violaceae; this family consists of 23 genera and more than 900 species all over the world. The plant has heart shaped leaves, sweet smelling flowers (violet or purple) and a creeping rhizomatous root system. Morphologically, the plant grows up to 10-15 cm height, and prefers to live in a moist, shady habitat. This nomenclature is based on the term odorata meaning fragrant in Latin as its flowers are a well-known contributor of the natural violet fragrance extracted to perfumery scent and aromatherapy[9].
The botanical classification is as follows:
Historical and cultural significance
Traditionally, Viola odorata is very significant in some traditional medical systems. Violets also represent love and fertility and were placed in flower garlands and used in medicine in ancient Greece and Rome. Hippocrates, the father of medicine wrote down that violets were used to treat headaches, respiratory infections and even insomnia. In the Middle Ages violets were grown in monastic gardens to be used as medicine and they came to make an important part of medieval European materia medica[10]. V. odorata is referred to as Banafsha and is valued in Ayurveda, being used in formulations to balance Pitta dosha by virtue of its cooling effect. Violet-based syrups and decoctions as antipyretics, expectorants, and sedatives have been used in Unani and Traditional Persian Medicine practice mostly to treat respiratory and febrile diseases[11]. There was also the use of Sharbat Banafsha, violet-flower syrup, and this is still used in the South Asian countries to overcome sore throats, dry coughs and congestion in the respiratory system.
The cultural uses of the plant spread to the culinary and the cosmetic spheres as well[12]. Candied violets, violet syrups and violet-scented oils and balms were considered luxuries in Victorian England. Although dwarfed by newer man-made drugs, the revival of curiosity in plant-based medicines has once again has led scientists to becoming interested in V. odorata[13].
Rationale for the Study
This rise in the popularity of herbal medicines all over the world is attributed to the efforts to seek alternatives to synthetic drugs, which are safer, cheaper, and more effective. Due to ethnobotanical background and a multitude of possible pharmacological applications, plants such as Viola odorata are currently regarded once again as potential sources of new pharmacological agents[14]. There is, however, one fundamental missing link that is a systematic integration of scientific evidence on the bioactive compounds and pharmacological pathways of V. odorata.
Majority of traditional uses of V. odorata are empirical and are not scientifically-validated practices that date many centuries back. Through the development of phytochemical studies and pharmacological testing, knowledge has become insufficient without bridging the gap between traditional and scientific knowledge[15]. Recent literatures have shed some light on the anti-inflammatory, antimicrobial, and even anticancer properties of V. odorata extracts, but there exist no reviews that summarize these findings in detail[16]. The proposed review will provide a comprehensive discussion of the phytochemical constituents reported in V. odorata, overview of its traditional applications in different medical system and the pharmacological changes reported in modern research. In this way, the review is aimed to offer a basis to further research into the clinical use of V. odorata so as to support its further incorporation to the framework of modern medicine[17].
Global distribution and habitat
Viola odorata grows most in temperate parts of Europe, North Africa and western Asia. It has been naturalized and introduced to North America, Australia and India sub-continent. The plant prefers moist woodland, and forest border, and garden cultivated habitats. Its flexibility to the different climatic conditions has enabled it spreading widely distributed. It is mainly grown in the Himalayas of Jammu & Kashmir, Himachal Pradesh and Uttarakhand in India[18]. V. odorata can be propagated in home gardens due to its popularity as an ornamental plant, because of its scented flowers. Wild-harvested specimens located in forest places, however, tend to be used in more traditional form of medicine and thus a need to ensure sustainable harvesting occurs to reduce over harvesting[19].
Pharmacognostic characteristics
The authentication and quality control of the use of Viola odorata cannot be overlooked in macroscopic and microscopic pharmacognostic assessments, particularly given adulteration and substitution in the herbal market[20]. The dehydrated flowers have a typical violet-like smell, are usually deep purple to bluish in color, and mucilaginous in nature when immersed in water. The histological tests provide the characters of unicellular trichomes, anomocytic stomata and mucilage cells in plenty that help in distinguishing species. The highest medicinal properties are usually snatched by the aerial parts, particularly by the flowers and the leaves, nonetheless, the roots and seeds also contain the bioactive components. The dainty chemical composition of this plant requires scrupulous processing and preservation environment in order to maintain its pharma activity[21].
Ethnopharmacological insights
Traditional uses of V. odorata are ethnopharmacologically documented to be highly diverse across the globe. Ayurveda it is termed as Sheet Virya (cold potency) and is used in inflammatory and febrile conditions[22]. Its mucilage constituent is especially in demand because it is soothing to mucous membranes of the respiratory and the gastro-intestinal systems. In Unani system, V. odorata falls in the group of Muqawwi-e-Aasab (nervine tonics), and has been used to treat epilepsy and melancholia[23]. Violet leaf has also been used as a poultice applied to skin infections, boils and ulcers by European herbalists. An infusion of the flowers was used to treat sleeplessness, headache and as a light laxative. The therapeutic flexibility of V. odorata can also be illustrated by Traditional Persian Medicine which utilises it as a treatment in cases of pleurisy, bronchitis, urinary tract infection and arthritis[24].
Contemporary pharmacological research
A variety of contemporary scientific studies have been initiated to confirm the existing therapeutic claims of Viola odorata based on its traditional applications. Phytochemical studies show that a wide range of bioactive constituents exist such as flavonoids (rutin, quercetin, kaempferol), phenolic acids (gallic acid, caffeic acid), alkaloids (odoratine), saponins and volatile oils, which include ionone derivatives[25]. These components provide several biological activities such as anti-oxidant, anti-inflammatory, antimicrobial and anticancerous benefits. On experimental analysis, it was proven that V. odorata extracts possess considerable free radical scavenging activity, a factor that could be explained by the high phenolic and flavonoid content. It is associated with anti-inflammatory properties, namely, inhibition of pro-inflammatory mediators like TNF-alpha and COX-2. The antimicrobial assays demonstrated efficacy as antimicrobial against Gram-positive and Gram-negative bacterium and antifungal toward Candida species[26]. The cytotoxicity could not be linked with any significant anticancer effects except during the preliminary study on breast and colon cancer cell lines; however, there is the need to conduct deeper studies. Neuropharmacology research showed the sedative and anxiolytic properties of V. odorata, which may be related to GABAergic mechanism, making this plant to be used traditionally in the treatment of insomnia and nervous disorders legitimately. Its saponin and mucilage content are referred to explain the expectorant and antitussive properties and in vivo animal studies have substantiated their therapeutic significance in respiratory medicine[27]. Although there are several sources of ethnobotanical information on the topic, little effort has been made so far to provide in-depth overviews of the potential therapeutic properties of Viola odorata, and to assemble the available information and compare the results. This kind of synthesis is essential so as to enable it to come up with standardize herbal preparation, foster clinical research and inform regulatory frameworks in the medicinal use of herbs[28]. Also, investigations on its pharmacokinetics, bioavailability and toxicity effects are highly necessary in expanding its traditional indications into sound clinical practice. The present review will make effort to fill this knowledge gap by presenting a comprehensive account of the phytochemistry of V. odorata as well as its traditional uses and its pharmacological activities. In the light of ethnobotanical records, phytochemical studies, and pharmacological analysis, the review attempts to present an enlightening view on the therapeutic application of V. odorata and thereby highlights its potential in formation of promising new plants as therapeutics[29].
Phytochemistry of Viola odorata (Linn.)
Viola odorata Linn., popularly recognized as Sweet Violet has a rich background of phytochemical constituents due to which the medicinal properties of this plant are well traced. Pharmacologically, the plant is a trove of different secondary metabolites such as flavonoids, alkaloids, saponins, essential oils, phenolic compounds, and mucilage, which offer assistance individually on its immense range of therapeutics Fig.1. Discovery of the extensive mechanism of these bioactive constituents is crucial to reveal the therapeutic potential of the plant and to pave the way to design standardized herbal preparations[30].
Fig.1: Phytochemistry of Viola odorata
Flavonoids
Flavonoids are one of the most enriched types of phytochemicals in Viola odorata with high concentrates found in its leaves and flowers. High flavonoids were found to be rutin (quercetin-3-O-rutinoside), quercetin, kaempferol, isorhamnetin, and violanthin. The glycoside quercetin, rutin, also exhibits strong antioxidant and vascular protection which makes the plant anti-inflammatory and anti- edematous[31]. Quercetin and kaempferol are famous due to the free radical intake capacity (that prevents cell damage caused by oxidative stress). Further, such flavonoids regulate inflammatory processes by suppressing some major enzymes such as cyclooxygenase (COX) and lipoxygenase (LOX), thus minimizing pro-inflammatory buffer transmission of pro-inflammatory mediators such as prostaglandins and leukotrienes. An anti-allergic, hepatoprotective effect is also provided by isorhamnetin, another methylated flavonoid, and violanthin, a very special flavone glycoside, is partially responsible, which contributes to the widespread use of the plant to treat inflammatory and respiratory diseases. All these flavonoids make the main substance of antioxidant and anti-inflammatory V. odorata[32].
Alkaloids
Alkaloids are compounds of organic matter that contain nitrogen and have great biological activity, and alkaloids are of great importance in the antimicrobial effect and the neuropharmacological effect of V. odorata. The previous studies on V. odorata revealed that its main alkaloid is an indole alkaloid odoratine, which has antimicrobial and cytotoxic effects. Odoratine has also been displayed to restrain the growth of pathogenic bacteria and fungi and thus helps to validate the traditional use of the plant in infections and skin conditions. The other well-known alkaloid is violine which has mild sedative and anxiolytic properties and thus leads to the use of V. odorata in the treatment of sleeplessness and nervousness. Derivatives of tryptamine, which are isomorphs of neurotransmitters such as serotonin, have also been found, pointing to the possibility of involvement in the mood control and neurological processes. It is therefore part and parcel of V. odorata alkaloid profile to be applied in antimicrobial, anticancer and nervine tonic in traditional medicine[33].
Saponins
Saponins are glycosidic compounds that are identified by their soap like lathering property and Viola odorata possesses an abundance of it in the aerial parts of the plant. They have varying biological activities with expectiorant, immunomodulatory and anti-inflammatory effects. V. odorata saponin content is said to account much of the expectorant feature the plant has as it helps to expel mucus present in the respiratory tract by thinning its consistency and stimulating the bronchial secretions. This is the basis of its historical usage in the treatment of coughs, bronchitis and other respiratory illnesses. Also, saponins strengthen the immune system by stimulating the secretion of cytokines, and macrophage activation, thus playing the role of the plant in fighting infections. They are also antimicrobial due to their membrane permeabilization effect. All in all, saponins are paramount in respiratory and immune-modulation gains that come along with V. odorata[34].
Essential oils
The essential oil fraction of Viola odorata flowers explain its sweet tensorial aroma, but it also provides the essential flower with many therapeutic qualities. The key volatile compounds that have been detected in the essential oil are alpha-ionone, beta-ionone, methyl salicylate, eugenol, and benzyl alcohol. Degraded carotenoid-derivatives that provide the dainty violet smell and have been corresponded with anti-oxidant and anti-inflammatory activities are ionones. Methyl salicylate is a natural example of a salicylate ester having analgesic and anti-inflammatory effects and so it is useful in management of topical musculoskeletal pain and inflammatory conditions. Eugenol, which is a phenolic compound, helps in giving the essential oil antimicrobial and anesthetic properties and benzyl alcohol helps in providing mild effects of antimicrobial and as a preservative. The usefulness of the essential oils extracted by V. odorata is, therefore, not only measured as of use in perfumery only but also contributes to increased pharmacological value of the plant especially in microbial infestations and inflammation[35].
Phenolic compounds
The other important group of bioactive substances in Viola odorata is phenolic acids and its derivatives. The major phenolics that are found are gallic acid, caffeic acid, chlorogenic acid, ferulic acid as well as vanillic acid. These are well known compounds with very strong antioxidant activities that are essential in scavenging of the free radicals, and in the provision of protection against oxidative damage to cells. An example is gallic acid that has anti-inflammatory activity and antimicrobial and anticancer properties and caffeic acid which has hepatoprotective and neuroprotective action[36]. Chlorogenic acid is a conjugated form of caffeic and quinic acid and helps in regulating the process of glucose metabolism and possesses a high antioxidant ability. Ferulic and vanillic acids also contribute to the plant capability of overcoming oxidative stress that lowers the possibility of degenerative diseases that are the results of oxidative stress, including cardiovascular diseases, neurodegenerative disorders, and cancer. These also form part of the antimicrobial effects on V. odorata, where such phenolic compounds inhibit growth of the microbe and kill it as they disrupt microbial cell walls[37].
Mucilage and Polysaccharides
Another large group of bioactive compounds in Viola odorata is phenolic acids and their derivatives. Best known phenolics are gallic acid, caffeic acid, chlorogenic acid, ferulic acid and vanillic acid. These are compounds that are famed with antioxidant properties that are very crucial in countering free radicals and helping the cells to avoid oxidative reaction. An example of this is gallic acid which has been found to possess some anti-inflammatory as well as antimicrobial and anticancer properties and caffeic acid, which is said to be hepatoprotective and neuroprotective. Chlorogenic acid is a combination between caffeic and quinic acid, it helps in the regulation of glucose metabolism and shows great antioxidant properties[38]. The existence of ferulic and vanillic acids, additionally, expands the potential of the plant to deal with oxidative stress, thus cutting on the danger of chronicle pathologies associated with oxidative harm, e.g., cardiovascular diseases, neurodegeneration, and cancer. The presence of these phenolic compounds is also one of the antimicrobial activity of V. odorata where the integrity of microbial cell walls is disrupted and its growth is halted[39].
Traditional Uses of Viola odorata (Linn.)
Sweet Violet (Viola odorata Linn.) holds a renowned folklore in many traditional medical systems such as the Ayurveda, Unani medicine, Siddha and the Traditional Persian Medicine (TPM). It has a very broad scope of therapeutic use and this is due to the fact that it has a great phytochemical content that lends it anti-inflammatory, expectorant, antimicrobial and neuroprotective effects. Various parts of the plant or rather leaves and flowers have been widely exploited by the traditional healers to treat as well as manage several respiratory ailments, skin disorders, inflammatory diseases, febrile diseases, nervous disorders and in the management of even cardiovascular complications. Its big traditional uses are explained under the following parts[40].
Respiratory disorders
Management of respiratory ailments is one of the most outstanding and well reported uses of Viola odorata in traditional medicine. The Ayurveda and Unani medicine have a high degree of admiration to this plant due to the expectorant and demulcent effects, which are used in treating cough, bronchitis, asthma and sore throat[41]. The saponins and mucilage in V. odorata are listed to loosen and to dislodge phlegm in the lungs pathways that relieve you of breathing and chest clogging. The flowers are used in the form of decoctions and syrups which are also commonly called Sharbat Banafsha in Unani medicines and are traditionally used in dry and productive cough, hoarseness of voice, throat irritation. The plant has a soothing effect on the mucosal tissues and this is why the plant is the best to tackle diseases such as laryngitis and pharyngitis. Violet-based formulations play other roles in the Traditional Persian Medicine related to the treatment of pleurisy, and reduction of effects of influenza and common cold. Phytotherapeutic potential V. odorata to act as an antitussive and mucolytic agent has been recognized extensively in folk medicine and has been utilized abundantly in Situs herbal tees and lozenges in attempts to reduce the burden of respiratory discomfort[42].
Skin conditions
Viola odorata was in use traditionally as treatment against different skin diseases such as eczema, acne, boils and inflammatory dermatoses. Poultices, ointments, infused oils all using the leaves and flowers are used to calm troubled skin that is inflamed and irritated. It has anti inflammatory, antimicrobial, and emolient qualities and hence it may be used to reduce redness, swelling, and infection caused due to skin disorders. In European customs the folk-healers used violet-leaves as poultices to the abscesses and the ulcers in order to come heal and to bear possible infection. V. odorata is also cool and soothing and used as a component ingredient in combination medication to treat sunburn, heat rash and insect bites. In addition, in Ayurveda, the plant can be used to correct the Pitta dosha, which is linked to skin inflammation and sensitization. There remains in many cultures the classical topical use of violet-infused oils and pastes to treat long term skin conditions such as psoriasis and dermatitis[43].
Anti-inflammatory uses
Viola odorata is used in traditional medicine as one of the common inflammatory phenomena which are underlying causes of many disorders. It is believed that the plant is anti-inflammatory due to a high flavonoids, saponins, phenolic acids, volatile oils such as methyl salicylate content. Traditionally V. odorata was used to treat the pain of musculoskeletal and joint inflammation and rheumatism[44]. Aerial parts are used to make Decoctions that are taken internally, and topical oils of violet flowers are used on inflamed muscles and joints as well as in poultices. Violet oil has beneficial uses in Unani medicine wherein it is used widely as a medication to heal Waram (inflammation) and during massage/treatment to loosen stiffness and pain. Because of its capacity to stimulate inflammatory pathways and uptake of the inflammatory mediators, its use has been perceived in the Persian and European traditional practice against diseases such as arthritis, gout, and body ache in general[45].
Antipyretic
Viola odorata has been used to a great extent in traditional medicines to treat fever condition because of its cooling and antipyretic effect. In Ayurveda it is known as Sheet Virya (cold potency) and is used to counter overheating in the body and therefore in checking fever. They are also used in traditional preparations such as Sharbat Banafsha which is used in patients with seasonal fevers, flu and heat related sickness[46]. The demulcent and mucilaginous property of the plant assists in cooling down the body besides providing relief to the throat and calming down the condition of high fevers. V. odorata is used as a mild febrifuge in Unani medicine and in low grade fevers and febrile diseases with respiratory symptoms. Moreover, violet-colored waters also were, traditionally, consumed in Europe to cool it, to bring down fever, especially in children with viral ailments. It is also gentle in antipyretic action and can therefore be used pediatrically[47].
Nervine Tonic
Viola odorata is documented in Unani, Traditional Persian Medicine, and European herbal medical traditions, as a nervine tonic. Traditionally the plant has been used in the treatment of the neurological disorders like insomnia, anxiety, melancholia, epilepsy and even in hysteria. Sedative and herbal properties are attributed to the alkaloids such as violine, flavonoids which regulate the neurotransmitter activity[48]. Syrups and infusions of violet are taken to produce a restful effect, get rid of nervous tension, and sleep peacefully. It is listed under the books in Unani practice, under the section of Muqawwi-e-Aasab (nerve strengtheners) and believed to strengthen the nervous system. Western herbal traditions have also recognised the anxiolytic, and mild hypnotic effects of violet, and it has been used in calming teas and as an adjunct in the treatment of nervous prostration. Further, the neuroprotective effects of V. odorata corroborate with the historical application of the plant in the treatment of symptoms of neurodegenerative conditions and mood disorder[49].
Cardiovascular benefits
Although not to the same degree as its respiratory or antiinflammatory actions, Viola odorata has been traditionally known to possess mild cardiotonic and antihypertensive activity. In Unani medicine it has been regarded as one of the delicate heart medicines that can help in the balance of functioning of the heart especially in its palpitation and tachycardia due to anxiety. Its mild sedative effects can help in restoring the heart and countering the cardiac disorders caused by stress. It has also been reported that violet flower infusions may be used to treat high blood pressure which can be attributed to the vasodilatory and diuretic effects caused by flavonoids in it. Also, V. odorata antioxidants are believed to have the properties of cardiovascular protection since they mitigate oxidative stress as well as enhancing endothelial functioning. Its well-established role as a heart-calming medicine has not been evaluated at length in the present-day cardiovascular pharmacological literature but is a significant part of its holistic medical profile[50].
Pharmacological activities of Viola odorata (Linn.)
Viola odorata Linn. Sweet Violet is multi-pharmacologically active, due to the variety of its constituents, namely flavonoids, alkaloids, saponins, phenolic acids, and essential oils. Its age-old medicinal usage has earned much credible research in modern times that proved its value to counter oxidative stress, microbial diseases, inflammations, and cancer besides neuro disorders, respiratory challenges, and diagnostic pain-related conditions.
Fig.2: Pharmacological activities of Viola odorata Linn.
Antioxidant activity
Viola odorata has one of the most researched pharmacological groups of its antioxidant potential. The plant contains a lot of flavonoids (quercetin, rutin, kaempferol), phenolic acids (gallic acid, caffeic acid) and anthocyanins all of which have very high free radical scavenging powers. DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) assays showed convincingly high antioxidant capacity of V. odorata extracts. These antioxidants are crucial in the scavenging of reactive oxygen species (ROS) and thereby safeguarding the biomolecules against oxidative damage known to be associated with chronic diseases such as cancer, cardiovascular diseases, and neurodegenerative diseases[51].
Antimicrobial activity
Viola odorata has significant antimicrobial properties and has already been scientifically confirmed in vitro experiments against a wide range of pathogenic species such as Gram-positive and Gram-negative bacteria and fungi. The antimicrobial activity of the essential oil constituents of the plant, especially eugenol, methyl salicylate, and benzyl alcohol is due to the cell membrane action and prevention of biofilms. Research done in the period between 2021 and 2025 has demonstrated that methanol extracts of V. odorata flowers have inhibitory properties against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The presence of the saponins and the alkaloids of this plant also add on to the level of its antimicrobial and this is done by making the membranes more permeable and also leaving the microbial enzymes inactive. This is in line with its conventional application in the treatment of skin, throat infections, and the respiratory tract infection. In addition, V. odorata extracts have also been shown to have antiviral potential, having shown preliminary evidence of inhibitory action against some respiratory viruses[52].
Anti-inflammatory activity
Both traditional medicine and modern scientific studies have proved the anti-inflammatory characteristics of Viola odorata. Anti-inflammatory effects of flavonoids, saponins, phenolic acids and coumarins found in the plant, entail the modulations of the inflammatory mediators that include, prostaglandins, cytokines (TNF-alpha, IL-6) and enzymes like, COX-2 and LOX. In recent studies V. odorata extracts have been shown to suppress the nitric oxide production of the LPS-stimulated macrophage, which, in effect, reduces the inflammatory effects. After the use of V. odorata in animal model studies there was a great reduction in paw edema and inflammatory markers, which supports its utilization in treatments associated with inflammatory diseases such as arthritis, gout, and musculoskeletal pains. Such findings add support to the use of topical application of violet oil and poultices traditionally applied in cases of swelling and joints inflammation[53].
Anticancer activity
In spite of being under laboratory study, initial evidence shows that Viola odorata phytochemicals have anticancerous potential. In-vitro studies on the cytotoxicity of the alkaloids like odoratine and the flavonoids like quercetin revealed their anti-proliferative action against several cancer cell lines like breast (MCF-7), colon (HCT-116), and cervical (HeLa) cancer cells. Mechanistic studies have indicated that these compounds cause apoptosis through mitochondrial pathway, interrupt cell cycle progression and inhibit cell angiogenesis. A recent study (2024) suggested that shares of methanolic extracts of in vitro flow of V. odorata significantly altered the viability of MCF-7 cells, indicating its possible chemopreventive activity in breast cancer cell lines. Furthermore, the high content of antioxidants of the plant can also help to decrease the levels of oxidative DNA damage, which is of extreme importance to carcinogenesis. Even though the results are promising, additional in vivo research and clinical trials are warranted to validate V. odorata as an anticancer agent[54].
Neuroprotective effects
Viola odorata has had a long tradition as a nervine tonic where pharmacological reports have started to decipher its neuroprotective actions. V. odorata is supposed to have sedative and anxiolytic properties related to the presence of alkaloids, such as violine, and flavonols, with the properties of interacting with GABAergic neurotransmission. According to experimental models, V. odorata extracts have shown the potential to alleviate anxiety-like behavior, sleep latency, and possess low anticonvulsant actions. A neuroprotective study indicates that V. odorata extracts reduce neuroinflammation processes and oxidative stress of neuronal cells and thus they help to guard against neurodegenerative disorders, such as Alzheimer and Parkinson diseases. The antioxidant component of the plant prevents neuronal damage through free radical scavenging and free radical scavenging and implicitly through endogenous antioxidant enzyme activation (e.g., SOD, CAT). Moreover, the violet syrups with proven longtime applications in the control of nervous agitation are explored as possible relief of stress-based neurocognitive disorder[55].
Expectorant and antitussive activity
Viola odorata is widely used in treating the respiratory pathologies like bronchitis, asthma, and coughing through expectorant and antitussive effects. Saponins found in the plant make bronchial secretions less viscous and this leads to easier expiration of sputum. Mucilage. Another active ingredient has a demulcent effect of creating a soothing layer over inflamed mucous membranes, and it shows a calming effect on the throat irritation and inhibition of the cough. The latest clinical trials have revealed that, V. odorata based syrups have shown significant effect in clearing sputum and the frequenc of coughs, in patients that use it. Moreover, experiments with animals have also established that aqueous preparations of V. odorata have the same anticough action as conventional cough suppressants. This evidence justifies the conventional application of the Sharbat Banafsha as herb remedy on breathing disorders, and justifies its application in contemporary phytotherapeutic preparations against cough and cold[56].
Analgesic and antipyretic effects
Viola odorata with analgesic and antipyretic effects has long been valued in traditional systems of medicines, especially in conditions of fever, headaches and musculoskeletal pains. Its analgesic properties are mainly due to its natural analgesic compound called methyl salicylate contained in its essential oil, which has the mechanisms of inhibition of the synthesis of prostaglandins and adjustment of peripheral pain pathways. According to recent experimental models, the ethanolic extracts of V. odorata exhibited strong analgesic effects on both the tail-flick and hot plate tests, which demonstrated that it has central and peripheral analgesic effects. It has anti-pyretic properties which are associated with its activity in thermo-regulation of the hypothalamus centers[57-60].
CONCLUSION
Sweet Violet, Viola odorata Linn., is one of the most impressive medicinal herbs which has a long history of traditional medicine utilization in many systems such as Ayurveda, Unani, Traditional Persian Medicine, and European folk therapy. Its various pharmacological properties, profoundly based on its phytochemical content, have increasingly been proved out by the modern scientific studies. The plant is a treasure-house of bioactive agents, flavonoids, alkaloids, saponins, phenolic acids, essential oils, coumarins, mucilage, and polysaccharides that have synergetic activity and a multi-dimensional effect of therapy. Some of its better-documented examples of pharmacological activity include strong antioxidant, antimicrobial, anti-inflammatory, expectorative, antitussive, analgesic, antipyretic, neuroprotection, and potential anticancer activities. Such biological properties are in line with its conventional use in treatment of respiratory illnesses, skin diseases, inflammatory illnesses, fever, nervous disorders and heart disorders. Its inhibitory effect on inflammation and oxidative stress is made possible by the antioxidant and anti-inflammatory processes that are facilitated by flavonoids and phenolic acids. Similarly, the saponins and mucilage are what give it its usefulness as an expectorant and demulcent in the respiratory tract infections. Recent pharmacology research has also focused on exploring V. odorata antimicrobial spectrum, immunomodulation and neuroprotective effects and the presence of cytotoxic properties in different types of cancer cell lines, which gives new scenarios as the adoption of the species by contemporary medicine. Although these results are encouraging, it is encouraging to note that there is a big gap between taking such preclinical studies to viable clinical trials to derive conclusively the efficacy and safety of V. odorata in human populations as well as standardization of dose. Viola odorata has a lot of potential to be developed as an origin of phytopharmaceutical preparations to respiratory, inflammatory, infectious, and neurodegenerative disorders with its comprehensive therapeutic profile. Nonetheless, future studies ought to continue on bioactivity-based division, mechanism, pharmacokinetics, and clinical confirmation to combine the traditional with contemporary evidence-based practice. As the demand in herbal remedies and natural therapeutics grows, V. odorata appears as a prospective contender in the field of integrative medicine in the future, which should be subjected to further investigation of scientists and primary clinical focus.
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