Indigofera linnaei (Fabaceae) Birdsville Indigo, Creeping Indigo, Nine-leaved Indigo

Quick Overview:

Indigofera linnaei is a low-growing, mat-forming perennial legume native to Australia and Southeast Asia of significant toxicological concern due to the presence of indospicine, a hepatotoxic amino acid. While it has a history of traditional external use for skin conditions and inflammation, its internal use is extremely dangerous and has caused severe livestock poisoning. Its primary modern significance is as a toxic pasture weed.

1. Taxonomic Insights

Species: Indigofera linnaei Ali (Syn. I. dominii, I. enneaphylla)

Family: Fabaceae (Legume or Pea family)

The Fabaceae family is vast, containing many important food crops, forage plants, and medicinal herbs. However, it also includes several notoriously toxic species. The Indigofera genus contains species used for dye, forage, and medicine, but several, including I. linnaei, are poisonous.

Related Herbs from the Same Family:

· Indigofera tinctoria (True Indigo): The classic source of blue indigo dye, also used in traditional medicine for conditions like epilepsy and skin ailments.

· Glycyrrhiza glabra (Licorice): A premier demulcent, anti-inflammatory, and adrenal tonic.

· Trigonella foenum-graecum (Fenugreek): A nutritive seed used for diabetes, digestion, and as a galactagogue.

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2. Common Names

Scientific Name: Indigofera linnaei | English: Birdsville Indigo, Creeping Indigo, Nine-leaved Indigo, Trailing Indigo | Australian: Birdsville Disease Plant | Thai: ครั่งดิน (Khrang din) | Sanskrit: Not classically described. May be cautiously grouped under अविषहा (Avishahā) or तृणमूषिका (Trinamushika) due to its toxic nature. | Hindi: बर्ड्सविल इंडिगो (Birdsville Indigo) |

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3. Medicinal Uses

Primary Actions (Traditional External Use ONLY): Anti-inflammatory, Astringent, Vulnerary (wound healing), Antipruritic.

Secondary Actions (TOXIC if Internalized): Potential Analgesic (folk use).

Medicinal Parts (Use with Extreme Caution):

· Whole Aerial Plant (Leaves, Stems): Used in traditional external poultices.

· Roots: Occasionally mentioned, but equally toxic.

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4. Phytochemicals Specific to the Plant and Their Action

· Indospicine: A rare hepatotoxic amino acid analog (arginine antagonist). Its action is severe hepatotoxicity (liver damage), causing centrilobular necrosis. It is also teratogenic (causes birth defects).

· 3-Nitropropionic Acid (3-NPA) and its glycosides (e.g., miserotoxin): Potent neurotoxins that inhibit mitochondrial respiration, leading to neurological damage and death in grazing animals.

· Tannins: Impart astringent properties for topical use.

· Flavonoids: May contribute to anti-inflammatory effects but are completely overshadowed by the toxins.

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5. Traditional and Ethnobotanical Uses Covering the Medicinal Uses

WARNING: These uses refer to external application only. Internal use is POISONOUS.

Vrana (Wounds) & Twak Vikara (Skin Sores, Ulcers)

Formulation: Fresh leaf poultice.

Preparation & Use: In some Australian Aboriginal and Southeast Asian traditions, crushed fresh leaves were applied as a poultice to minor cuts, sores, and chronic skin ulcers.

Reasoning: The astringent tannins help clean and contract the wound. Potential anti-inflammatory effects may reduce swelling. This must be done with care, avoiding any open wounds or mucous membranes to prevent toxin absorption.

Kandu (Itching) & Dadru (Fungal/Tinea Infections)

Formulation: Leaf wash or paste.

Preparation & Use: A decoction of leaves was used as a wash, or a paste applied to itchy skin rashes and fungal infections.

Reasoning: Astringent and potential mild antimicrobial properties may provide symptomatic relief. Effectiveness is questionable and risk of dermatitis is present.

Shotha (Inflammatory Swellings) - External

Formulation: Poultice on unbroken skin.

Preparation & Use: Crushed leaves applied to swellings, sprains, or inflamed joints.

Reasoning: Counter-irritant or anti-inflammatory effects may provide temporary relief. Not a recommended practice due to safety.

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6. Healing Recipes, Teas, Decoctions

This plant is NOT SAFE for home medicinal preparation. The following is for ethnobotanical understanding only.

Theoretical External Wash (Historical/Risky Practice):

Purpose: For stubborn skin sores (historical use).

Theoretical (Not Recommended) Preparation:

1. A handful of fresh leaves are boiled in 1 liter of water for 15 minutes.

2. The liquid is cooled completely and strained.

3. Used to wash the affected area. Even external use carries risk of absorption or accidental ingestion.

WARNING: There are no safe internal preparations of this plant. It should never be made into a tea, tincture, or ingested in any form.

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7. In-Depth Phytochemical Profile and Clinical Significance of Indigofera linnaei

Introduction

Indigofera linnaei, commonly known as Birdsville or Creeping Indigo, is a deceptively dangerous plant. Its small, pinnate leaves and pink-tinged flowers resemble many harmless legumes, but it is one of the most toxic pasture plants in Australia, responsible for widespread livestock deaths ("Birdsville Disease"). Its toxicology defines its entire profile. The plant contains a dual-toxin system—indospicine (a liver poison) and 3-nitropropionic acid (a nerve poison)—that makes it a significant agricultural hazard and a plant with no legitimate internal medicinal use.

1. Indospicine (The Hepatotoxic Agent)

Key Compound: L-Indospicine (a non-proteinogenic amino acid).

Actions and Clinical Relevance:

· Mechanism of Toxicity: Indospicine is an analog of arginine. It competitively inhibits arginase and incorporates into proteins in place of arginine, leading to the production of dysfunctional proteins. This disrupts the urea cycle and causes severe hepatocellular necrosis (death of liver cells), particularly in the centrilobular region.

· Clinical Signs: Poisoning leads to acute liver failure: jaundice, lethargy, anorexia, ascites (fluid buildup in the abdomen), and death. The toxin is cumulative and can be passed through meat, causing secondary poisoning in dogs and other carnivores.

· Teratogenicity: It causes fetal abnormalities and abortion in pregnant animals, highlighting its profound systemic toxicity.

2. 3-Nitropropionic Acid (3-NPA) (The Neurotoxic Agent)

Key Compound: 3-Nitropropionic acid, often stored as the glycoside miserotoxin.

Actions and Clinical Relevance:

· Mechanism of Toxicity: 3-NPA is a potent, irreversible inhibitor of succinate dehydrogenase, a key enzyme in the mitochondrial electron transport chain (Complex II). This inhibition halts cellular respiration, particularly in energy-demanding neurons, leading to ATP depletion and neuronal cell death.

· Clinical Signs: Neurological symptoms dominate: weakness, ataxia (staggering), knuckling of fetlocks, paralysis, and death from respiratory failure. This mirrors poisoning from other 3-NPA-containing plants.

An Integrated View of Toxicity and Folk Use in Indigofera linnaei

· The Pathophysiology of Poisoning: Ingestion, whether by livestock or humans, unleashes a two-pronged attack. Indospicine targets the liver, destroying its detoxification and synthetic functions. Concurrently, 3-NPA targets the nervous system, crippling motor function and respiration. This combination is often rapidly fatal, with liver failure and neurotoxicity compounding each other. There is no antidote.

· Why It Was Ever Used Topically: The existence of external folk use for wounds suggests that traditional practitioners may have recognized some surface-level astringent or anti-inflammatory property, likely from tannins or flavonoids. Critically, they also recognized its internal danger. This represents a careful, localized application of a broadly toxic plant—a high-risk practice that modern hygiene and safer alternatives have rendered obsolete.

· A Modern Herbalist's Perspective: From a clinical herbal standpoint, I. linnaei is contraindicated for any therapeutic use. Its risks are catastrophic, and its purported benefits (skin healing) are easily and safely obtained from countless other herbs (e.g., Centella asiatica, Calendula officinalis, Plantago major). Its monograph is essential primarily for toxicological identification and poisoning prevention.

· Public and Agricultural Health Hazard: Its primary significance today is as a invasive, toxic weed in pastures. Its ability to cause secondary poisoning (e.g., dogs eating poisoned meat) extends its risk. Public education on identifying and eradicating this plant is a matter of safety.

Conclusion: Indigofera linnaei is a severely toxic plant with a narrow and risky history of external folk use. Its biochemistry is defined by two potent, synergistic toxins—indospicine and 3-nitropropionic acid—that cause irreversible liver and neurological damage. While it holds a place in the ethnobotanical record, it holds absolutely no place in modern herbal medicine, home remedy, or any form of internal use. It stands as a stark warning of the deadly potential within the plant kingdom and underscores the paramount importance of certain botanical identification and toxicology knowledge for foragers, farmers, and herbalists alike.

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Disclaimer:

INDIGOFERA LINNAEI IS HIGHLY POISONOUS AND CAN BE FATAL. INTERNAL USE IS STRICTLY PROHIBITED.

All parts of the plant are toxic, both fresh and dried.

Ingestion can cause:

· Severe, irreversible liver damage (jaundice, liver failure, death).

· Severe neurological damage (staggering, weakness, paralysis, respiratory failure).

· Birth defects and abortion in pregnant humans and animals.

There is no safe dose. There is no antidote.

Secondary poisoning can occur in carnivores (e.g., dogs) consuming meat from poisoned animals.

Seek immediate medical attention if ingested.

Even external use is not recommended due to risk of accidental absorption or ingestion. This information is for toxicological and academic purposes only. This plant must never be used as medicine.

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8. Reference Books, Books for In-depth Study:

· Australia's Poisonous Plants, Fungi and Cyanobacteria by Ross McKenzie.

· Veterinary Toxicology: Basic and Clinical Principles by Ramesh C. Gupta.

· Handbook of Plant and Fungal Toxicants edited by J.P. Felix D'Mello.

· Toxic Plants of North America by George E. Burrows & Ronald J. Tyrl.

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9. Further Study: Plants That Might Interest You Due to Similar Properties (SAFER Alternatives or Related Toxins)

1. Indigofera tinctoria (True Indigo)

· Species: Indigofera tinctoria | Family: Fabaceae | Genus: Indigofera

· Similarities: A closely related species used for dye and traditional medicine (e.g., for skin conditions, epilepsy). It contains different, less acutely toxic compounds but still requires caution and expert guidance. It highlights the variability within a genus.

2. Crotalaria spp. (Rattlepods)

· Species: Crotalaria species | Family: Fabaceae | Genus: Crotalaria

· Similarities: Many Crotalaria species contain pyrrolizidine alkaloids (PAs), which cause similar chronic liver damage (veno-occlusive disease) as indospicine. Both are hepatotoxic legumes of significant concern in agriculture and toxicology.

3. Psoralea corylifolia (Babchi, Bakuchi)

· Species: Psoralea corylifolia | Family: Fabaceae | Genus: Psoralea

· Similarities: A safe and highly valued Ayurvedic legume used topically for vitiligo, psoriasis, and skin rejuvenation. It is an excellent example of a Fabaceae member with profound, safe dermatological applications, in stark contrast to I. linnaei.

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