Oxalis corniculata (Oxalidaceae) Creeping Woodsorrel

Das K
Apr 8
14 min read

Oxalis corniculata, commonly known as creeping woodsorrel or yellow sorrel, is a small but remarkably potent medicinal herb belonging to the Oxalidaceae family. Native to the Indian subcontinent, it has now spread across the globe as a cosmopolitan weed, thriving in warm temperate and tropical regions worldwide. Often dismissed as a garden nuisance, this humble plant has been a cornerstone of traditional medicine systems—including Ayurveda, Siddha, Unani, and Traditional Chinese Medicine—for centuries. Modern pharmacological research has begun to validate its traditional uses, uncovering a wealth of bioactive compounds that exhibit antioxidant, antimicrobial, anti-inflammatory, anticancer, and wound-healing properties.

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1. Taxonomic Insights

Species: Oxalis corniculata L.

Family: Oxalidaceae (Wood Sorrel Family)

The Oxalidaceae family, commonly known as the wood sorrel family, comprises approximately 800 species distributed across eight genera. The family is characterized by its typically clover-like leaves that are often sensitive to light and close at night (nyctinasty). Members of this family are known for their characteristic sour taste due to the presence of oxalic acid and other organic acids. The family is widely distributed in tropical and subtropical regions, with many species valued for their edible and medicinal properties.

Taxonomic Note: The species was first described by Carl Linnaeus in 1753. The genus name Oxalis is derived from the Greek word oxys, meaning "sharp" or "acidic," referring to the sour taste of the plant's leaves due to their oxalic acid content. The specific epithet corniculata means "horned," referring to the horn-like shape of the seed capsules. The plant is a small, creeping herb that roots at the nodes and has characteristic trifoliate leaves resembling clover. Its leaves are often purplish-brown, especially in sunny conditions, and its small yellow flowers are borne in axillary umbels.

Related Herbs from the Same Family:

· Oxalis acetosella (Wood Sorrel): A close relative with similar sour-tasting leaves, traditionally used as a cooling herb for fevers and inflammation. Its leaves are edible in small quantities but contain oxalic acid, which should be consumed in moderation.

· Averrhoa carambola (Starfruit): A tropical tree in the same family, bearing edible fruit known for its star-shaped cross-section. The fruit is a rich source of antioxidants and vitamin C.

· Biophytum sensitivum (Sensitive Plant): A related genus with leaves that are sensitive to touch. It is used in traditional medicine for its anti-inflammatory and wound-healing properties.

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2. Common Names:

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3. Medicinal Uses

Primary Actions: Antioxidant, Antimicrobial, Anti-inflammatory, Antidiarrheal, Wound Healing, Hepatoprotective

Secondary Actions: Anticancer, Antidiabetic, Cardioprotective, Neuroprotective, Antipyretic, Antiscorbutic, Gastroprotective

Medicinal Parts:

The whole plant (leaves, stems, flowers, and roots) is used medicinally, both fresh and dried.

· Leaves: The primary part used for making fresh juice and in salads. They are rich in flavonoids, phenolic acids, and vitamin C. The sour taste is due to oxalic and citric acids.

· Aerial Parts: Used in decoctions for fevers, dysentery, and as a cooling agent. Modern research confirms significant antioxidant and antimicrobial activities.

· Whole Plant: Used in traditional formulations for a wide range of ailments, including gastrointestinal disorders, skin conditions, and respiratory diseases. The plant is also included in several approved Chinese patent medicines.

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4. Phytochemicals Specific to the Plant and Their Action

The phytochemistry of O. corniculata is remarkably diverse, with recent analyses identifying 227 chemical constituents across various classes.

· Flavonoids (Predominant Class): Approximately 84 flavonoids have been identified, including isovitexin, isoorientin, luteolin, quercetin, apigenin, rutin, and schaftosides. Total flavonoid content can reach up to 13.5 mg/g. These compounds are responsible for the plant's potent antioxidant and anti-inflammatory activities. Hydroxylation at the 3, 5, and 7 positions and the presence of a C2=C3 double bond enhance radical-scavenging activity. C-glycosyl flavones (schaftoside, isoschaftoside) demonstrate strong radical-scavenging activity and superior structural stability, while O-glycosyl flavones (orientin, isoorientin, diosmin) exhibit enhanced solubility and absorption.

· Organic Acids: Phenolic acids (23 identified) dominate this class, with caffeic acid as the primary compound. Caffeic acid content peaks in dry-area samples (up to 1.28 μg/g) and exhibits strong free radical scavenging capacity. Low-molecular-weight organic acids such as oxalic, malic, and citric acids contribute to the plant's characteristic sour taste. Fatty acid-type organic acids, including oleic acid (31.08%) and palmitic acid (2.55%), have also been identified.

· Terpenoids: Twenty terpenoids have been identified, including monoterpenes and triterpenes. Geranyl acetate (13.3%), terpinolene (9.2%), linalool oxide (7.4%), and geraniol (6.4%) dominate the essential oil fraction and exhibit antimicrobial, antioxidant, and anti-inflammatory activities. Triterpenoids such as oleanolic acid, squalene, and phytol have also been detected in non-volatile fractions.

· Alkaloids: Five alkaloids have been reported, including trigonelline and betaine. Notably, a novel triazole alkaloid named Aspergillus triazolate A (ATA) was first isolated from O. corniculata. ATA has demonstrated α-glucosidase inhibitory activity, suggesting potential as an antidiabetic agent.

· Polysaccharides (OCP): Crude polysaccharides (OCP) are extracted with a total yield of 9.45%. The major fraction, OCP-3 (31.5 kDa), is primarily composed of arabinose (47.83%) and galacturonic acid (17.81%), demonstrating strong free radical scavenging capacity and protection against oxidative damage in both cell-based and in vivo models.

· Other Metabolites: Coumarins, anthraquinones, sterols (including β-sitosterol), saponins, cardiac glycosides, and phlobatannins have also been identified in the plant.

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5. Traditional and Ethnobotanical Uses Covering the Medicinal Uses

Atisara (Diarrhea) & Dysentery

Formulation: Whole plant juice, leaf decoction.

Preparation & Use: In Asia, this herbaceous plant is traditionally used for treating gastrointestinal disorders, including diarrhea and dysentery. The expressed juice is made into a sherbet and prescribed for dysentery and rectal prolapse. The methanolic extract of the leaf, containing flavonoids and phenolic acids such as rutin and ferulic acid, has shown efficacy against Shigella strains.

Reasoning: The antidiarrheal activity is attributed to the presence of flavonoids (rutin, quercetin), tannins, and phenolic acids, which exhibit astringent properties and inhibit the growth of pathogenic bacteria. The water extract has demonstrated greater efficacy than the methanolic extract in castor oil-induced diarrhea models.

Jwara (Fever) & Vishamajwara (Intermittent Fevers)

Formulation: Whole plant infusion or decoction.

Preparation & Use: The plant is considered cooling and antipyretic (febrifuge). In African folk medicine, it is traditionally used for fevers and respiratory diseases. An infusion of the whole plant is taken as a cooling drink to alleviate fever and biliousness. In Tanzania, it has been traditionally used for flu and as a remedy for tonsillitis.

Reasoning: The antipyretic effect is likely due to a combination of flavonoids, phenolic acids, and terpenoids with anti-inflammatory properties. The plant's cooling nature in traditional terms may also correlate with its ability to reduce oxidative stress and inflammation associated with fever.

Kshata (Wounds, Ulcers, and Skin Diseases)

Formulation: Leaf poultice, fresh juice.

Preparation & Use: The fresh leaves are made into a paste and applied topically to treat wounds, corns, warts, and other excrescences on the skin. The juice of the leaves is used externally to remove opacities of the cornea in traditional Indian medicine. An infusion of the leaves is used externally for eye ailments. Petroleum ether and alcohol extracts of the plant have shown potential wound-healing activity in animal models, evidenced by their ability to promote granulation tissue formation, collagen synthesis, and wound closure.

Reasoning: The wound-healing properties are attributed to the presence of flavonoids (quercetin, kaempferol), terpenoids, and phenolic compounds, which promote tissue regeneration, reduce inflammation, and exhibit antimicrobial activity against skin pathogens. The astringent properties of tannins also help in wound contraction.

Mutrakrichra (Urinary Disorders) & Antiscorbutic

Formulation: Whole plant juice.

Preparation & Use: The plant is considered cooling and diuretic. The fresh juice is prescribed for urinary disorders and to allay thirst. It is also used as a remedy for scurvy (vitamin C deficiency), with local inhabitants in Pakistan using it for this purpose.

Reasoning: The plant's high vitamin C content and the presence of flavonoids (apigenin, luteolin) with diuretic properties support its traditional use. The antioxidant activity of polyphenols may also protect the urinary tract from oxidative stress.

Aruchi (Loss of Appetite) & Agnimandya (Digestive Weakness)

Formulation: Fresh leaves as a curry.

Preparation & Use: Fresh leaves are made into a curry, which is said to improve appetite and digestion in dyspeptic patients. The sour taste is believed to stimulate digestive fire (agni) in Ayurvedic tradition.

Reasoning: The organic acids (citric, malic acids) present in the leaves stimulate salivary and gastric secretions, promoting appetite and digestion. The plant's mild astringent properties also help tone the digestive tract.

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6. Healing Recipes, Decoctions, and Preparations

Diarrhea and Dysentery Whole Plant Juice

Purpose: To manage acute diarrhea and dysentery.

Preparation & Use:

1. Take a handful of fresh Oxalis corniculata whole plant (about 20-30 grams).

2. Wash thoroughly and grind to extract the juice.

3. Strain the juice and mix with a pinch of rock salt and a teaspoon of honey.

4. Take 10-15 ml of this preparation, up to three times a day.

5. Safety Note: Do not exceed the recommended dose. Use under professional guidance for persistent or severe diarrhea.

Fever and Cooling Infusion

Purpose: To reduce fever and alleviate biliousness.

Preparation & Use:

1. Measure 2-3 grams (about 1 to 2 teaspoons) of dried whole plant.

2. Place in a cup and pour 250 ml of just-boiled water over the herb.

3. Cover and steep for 5-10 minutes, then strain.

4. The resulting infusion is taken warm or at room temperature, up to two cups per day for fever or as a cooling drink.

Wound and Skin Poultice

Purpose: For minor cuts, wounds, corns, warts, and skin irritations.

Preparation & Use:

1. Take a handful of fresh Oxalis corniculata leaves.

2. Crush or blend into a fine pulp.

3. Apply directly to the affected area, cover with a clean cloth, and leave for 30-60 minutes.

4. Rinse with warm water. Use twice daily as needed.

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Culinary Uses of Oxalis corniculata (Creeping Woodsorrel)

The plant has a characteristic sour, lemony flavor and is used as a wild edible in various cultures.

1. Salad Uses (Leaves and Stems)

The tender leaves and stems are used raw in salads.

Preparation: The youngest, most tender leaves and succulent stems are the best choice. They have a pleasant, tart, lemony flavor. To prepare, wash the leaves thoroughly and pat them dry. They can be used whole or chopped and mixed into green salads.

Flavour Profile: Tart, lemony, and refreshing, similar to sorrel or wild spinach. The sour taste is due to the presence of oxalic and citric acids. It adds a bright, acidic note to salads and can be used as a substitute for vinegar or lemon juice.

2. Chutneys and Relishes

In India, the sour-tasting leaves are used to make tangy chutneys and relishes.

Preparation: Wash a handful of fresh leaves, grind them with green chilies, coriander leaves, salt, and a little water. This chutney is traditionally served with meals to stimulate appetite.

Flavour Profile: Sharp, tangy, and spicy. It acts as an excellent digestive and palate cleanser.

3. Soups and Stews

Creeping woodsorrel can be used as a souring agent in soups and stews.

Preparation: Add a handful of washed leaves to soups or stews during the last 5-10 minutes of cooking. The leaves will wilt and release their sour flavor, enhancing the dish without the need for lemon juice or vinegar.

Flavour Profile: The plant adds a pleasant sourness and a slight green flavor to soups.

Foraging and Preparation Notes

Harvesting: Always pick young, tender leaves and stems from clean, unpolluted areas away from roadsides and agricultural land. The plant is often found as a weed in gardens and fields.

Oxalic Acid Caution: The leaves contain oxalic acid, which can be problematic in large quantities for individuals with kidney stones or gout. Moderate consumption as a culinary herb or small doses medicinally is generally considered safe. A brief blanching in boiling water (1 minute) can reduce the oxalic acid content. People with a history of kidney stones should avoid excessive consumption.

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7. In-Depth Phytochemical Profile and Clinical Significance of Oxalis corniculata (Creeping Woodsorrel)

Introduction

Oxalis corniculata, often viewed as a pervasive garden weed, is actually a botanical powerhouse with a rich history in traditional medicine. Revered in Ayurveda as Changeri and integrated into the pharmacopoeias of various cultures from Southeast Asia to Africa, this small, creeping herb is now attracting significant scientific interest. Modern research has confirmed that its humble appearance belies a remarkable chemical sophistication. Contemporary analytical chemistry has identified hundreds of bioactive compounds, including an impressive arsenal of antioxidants, antimicrobial agents, and novel bioactive molecules. The discovery of its potent antioxidant, anti-inflammatory, and gastroprotective activities provides a mechanistic basis for its traditional uses in dysentery, fevers, and wound healing, placing O. corniculata firmly among the most promising medicinal weeds in the modern pharmacopoeia.

1. Flavonoids: The Antioxidant and Anti-inflammatory Powerhouse

· Key Compounds: Isovitexin, Isoorientin, Vitexin, Luteolin (Corniculatin A), Quercetin, Rutin, Apigenin 7,4′-diglucoside, Schaftoside, Isoschaftoside.

· Pharmacological Profile: This is the most abundant class of compounds in O. corniculata, with approximately 84 distinct flavonoids identified. They are the primary drivers of the plant's antioxidant and anti-inflammatory activities.

· Actions and Clinical Relevance:

· Antioxidant: Flavonoids with hydroxylation at the 3, 5, and 7 positions and the C2=C3 double bond demonstrate enhanced radical-scavenging activity. The C-glycosyl flavones (schaftosides) are noted for their structural stability and strong radical-scavenging activity.

· Anti-inflammatory: Isoorientin has demonstrated anti-inflammatory properties in LPS-induced RAW cells and carrageenan-induced inflammatory models. Luteolin can reduce the phosphorylation of P38 MAPK and the activation of NF-κB induced by oxidative stress.

· Anticancer: Vitexin induces apoptosis in colon cancer cells and helps suppress drug resistance. Isovitexin triggers ER stress in liver cancer cells, leading to apoptosis and autophagy. Acacetin inhibits gastric cancer xenograft tumor growth by reducing EGFR phosphorylation.

· Antidiabetic: Swertisin has been shown to help regain pancreatic function in diabetic mice.

2. Organic Acids: Sour Taste with Therapeutic Depth

· Key Compounds: Caffeic acid, Chlorogenic acid, Ferulic acid, Vanillic acid, p-Hydroxybenzoic acid, Oxalic acid, Malic acid, Citric acid, Oleic acid.

· Pharmacological Profile: A total of 51 organic acids have been identified, including 23 phenolic acids. These contribute to the plant's characteristic sourness and its diverse biological activities.

· Actions and Clinical Relevance:

· Antioxidant: Caffeic acid and its derivatives exhibit strong free radical scavenging capacity, protecting cells against oxidative stress. Ferulic acid has been shown to inhibit 70.9% of lipid peroxidation in rat brain homogenates.

· Cardioprotective: Vanillic acid has been shown to significantly increase systolic blood pressure and partially restore heart rate to normal levels in doxorubicin-treated rats.

· Anticancer: Ethyl gallate reduces breast cancer cell growth by affecting the PI3K/Akt pathway and inhibiting NF-κB p-65, MMP-2, and MMP-9.

· Estrogenic Activity: p-Hydroxybenzoic acid has demonstrated estrogenic activity in MCF7 cells, suggesting potential relevance in hormonal regulation.

3. Alkaloids and Novel Bioactive Compounds

· Key Compounds: Aspergillus triazolate A (ATA), Trigonelline, Betaine.

· Pharmacological Profile: A novel triazole alkaloid, Aspergillus triazolate A, was first isolated from O. corniculata. This discovery highlights the plant's potential as a source for novel drug development.

· Actions and Clinical Relevance:

· Antidiabetic: ATA has been shown to lower blood glucose levels by inhibiting α-glucosidase (α-Glu). Its amphiphilic structure, combining a hydrophilic triazole ring and a hydrophobic C8 alkyl chain, facilitates stable interactions with the target enzyme, enhancing inhibitory activity.

· Osmotic and Metabolic Support: Betaine serves as an important osmolyte and methyl donor, with antioxidant, hepatoprotective, and metabolic regulatory effects.

4. Polysaccharides: Cellular Protection

· Key Compound: OCP-3 polysaccharide fraction.

· Pharmacological Profile: Polysaccharides (OCP) are extracted with a total yield of 9.45%. The major fraction, OCP-3 (31.5 kDa), is primarily composed of arabinose and galacturonic acid.

· Actions and Clinical Relevance:

· Antioxidant and Cellular Protection: OCP-3 demonstrates strong free radical scavenging capacity, suppresses lipid peroxidation, and confers protection against oxidative damage in both cell-based and in vivo models.

5. Terpenoids: Antimicrobial and Aromatic Qualities

· Key Compounds: Geranyl acetate, Terpinolene, Linalool, Geraniol, Oleanolic acid, Squalene, Phytol.

· Pharmacological Profile: The essential oil fraction of O. corniculata is dominated by monoterpenes, which are responsible for the plant's aromatic properties.

· Actions and Clinical Relevance:

· Antimicrobial: Geraniol, linalool, and other monoterpenes exhibit antimicrobial and anti-inflammatory activities.

· Diverse Pharmacological Effects: Oleanolic acid and squalene are triterpenoids associated with antioxidant, anti-inflammatory, and other health-promoting benefits.

An Integrated View of Healing in Oxalis corniculata

· For Gastrointestinal Health: The traditional use of the plant for diarrhea and dysentery is supported by its antimicrobial activity against pathogens like Shigella, Salmonella, and Vibrio cholerae, combined with its astringent properties due to tannins and flavonoids. The antidiarrheal effect of flavonoids like rutin further validates this traditional application.

· For Inflammation, Wounds, and Skin: The flavonoids (luteolin, quercetin), terpenoids, and phenolic acids collectively contribute to significant anti-inflammatory activity. This, combined with antimicrobial properties and the ability to promote collagen synthesis and wound closure, validates its use as a topical wound healer.

· As an Antioxidant and Cellular Protector: The high phenolic and flavonoid content, along with the OCP-3 polysaccharide, make O. corniculata a potent protector against oxidative stress, which is implicated in aging, cancer, diabetes, and neurodegenerative diseases.

· For Metabolic Health: The discovery of ATA as an α-glucosidase inhibitor and the antidiabetic activity of swertisin and β-sitosterol provide pharmacological evidence for its traditional use in managing diabetes.

Toxicological Profile and Quality Control

Safety Profile: O. corniculata is generally recognized as safe for moderate use. Cytotoxicity studies indicate mild activity against brine shrimp larvae (LC50 value of 156 μg/ml), suggesting low mammalian toxicity. However, due to its oxalic acid content, excessive intake can cause gastrointestinal irritation and may contribute to kidney stone formation in susceptible individuals. Pregnant or nursing women should consult a qualified healthcare professional before use.

Quality Control Parameters: The total flavonoid content (up to 13.5 mg/g) and total phenolic content (98.6 μg/g) serve as key markers for standardization. Identification of characteristic compounds such as isovitexin, isoorientin, and novel compounds like ATA can be used for quality control of extracts. The presence of specific flavonoids and organic acids can be confirmed using advanced techniques such as UHPLC-Q-Exactive-MS/MS, which has been used to identify 539 compounds in the decoction.

Conclusion

Oxalis corniculata exemplifies how a "weed" can be a hidden source of therapeutic treasure. From a humble plant used as a tangy salad green and a remedy for common ailments, it has emerged as a species with a remarkably rich phytochemical profile. The validation of its antioxidant, antimicrobial, anti-inflammatory, antidiabetic, and wound-healing activities, alongside the discovery of novel bioactive compounds like Aspergillus triazolate A, positions it as a valuable subject for further pharmaceutical and nutraceutical development. As research continues, O. corniculata stands as a testament to the power of rediscovering traditional knowledge through the lens of modern science, offering promising natural leads for addressing some of today's most pressing health challenges.

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Disclaimer:

Oxalis corniculata is generally considered safe for moderate culinary and medicinal use. However, the plant contains oxalic acid, which in large quantities can cause gastrointestinal irritation and may contribute to kidney stone formation in susceptible individuals. Pregnant or nursing women should consult a qualified healthcare professional before use. The antimicrobial and medicinal applications are supported by research, but this plant is not a substitute for conventional medical treatment. Always consult a qualified healthcare professional before using this plant for medicinal purposes. This information is for educational use only and is not a substitute for professional medical advice.

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8. Reference Books, Books for In-depth Study

· A Modern Herbal by Maud Grieve (1931) – for traditional uses of wood sorrel

· Indian Medicinal Plants: An Illustrated Dictionary by C.P. Khare – for Ayurvedic and regional uses

· Phytochemistry journal (various volumes) – for flavonoid and terpenoid research

· Journal of Ethnopharmacology – for pharmacological and traditional use studies

· Beni-Suef University Journal of Basic and Applied Sciences (2024, Vol. 13) – for comprehensive review on ethnopharmacology and therapeutic potentials

· Antioxidants journal (2025, Vol. 14) – for phytochemistry, bioactivities, and application potential

· Flora of North America – for botanical description and distribution

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9. Further Study: Plants That Might Interest You Due to Similar Medicinal Properties

1. Oxalis acetosella (Wood Sorrel)

· Species: Oxalis acetosella | Family: Oxalidaceae

· Similarities: A close relative sharing similar sour-tasting leaves, traditional use as a cooling herb for fevers and inflammation, and similar antioxidant properties due to flavonoids. It is more commonly used in European folk medicine as a diuretic and for scurvy.

2. Rumex acetosa (Garden Sorrel)

· Species: Rumex acetosa | Family: Polygonaceae

· Similarities: Another plant with a sour taste due to oxalic acid, used similarly as a cooling herb, diuretic, and for digestive complaints. Garden sorrel is more widely cultivated as a culinary herb and is valued for its lemony flavor. Both plants share traditional uses for fevers and as an antiscorbutic.

3. Hibiscus sabdariffa (Roselle)

· Species: Hibiscus sabdariffa | Family: Malvaceae

· Similarities: Shares a sour taste and is renowned for its cooling, diuretic, and antioxidant properties. Roselle is more widely used as a beverage (hibiscus tea) and is valued for its antihypertensive and hepatoprotective properties. Both plants are rich in organic acids and anthocyanins.

4. Taraxacum officinale (Dandelion)

· Species: Taraxacum officinale | Family: Asteraceae

· Similarities: Like Oxalis, dandelion is a cosmopolitan weed with a long history of use as a diuretic, digestive tonic, and for skin conditions. Dandelion is more widely researched for its hepatoprotective and prebiotic properties. Both plants are considered valuable wild edibles and are rich in antioxidants.

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PREHEALING

Oxalis corniculata (Oxalidaceae) Creeping Woodsorrel

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