Tephrosia purpurea, known locally as Kathurupila and in English as purple tephrosia, is a small but remarkably versatile herb with deep roots in South Asian traditional medicine. A member of the Fabaceae (legume) family, this annual or short-lived perennial grows wild across Sri Lanka, India, and much of tropical Asia and Africa, thriving in disturbed ground, roadsides, and open scrubland. Its significance stretches from Ayurvedic pharmacy to subsistence agriculture, and its biochemistry has attracted modern scientific attention.
What does Tephrosia purpurea look like?
The plant is erect to spreading, typically reaching 40–80 cm in height, though specimens up to 1.5 metres are recorded. Stems branch freely, giving bushy plants a somewhat sprawling silhouette. Leaves are pinnately compound, with small leaflets that are grayish-green on the undersurface due to a fine covering of hairs. Flowers are small and purple to pink — characteristic of the wider Tephrosia genus — and appear in short, axillary racemes.
One of the most reliable identification features is the pod. Each pod is distinctly convex around the seeds with a flat, pinched area between them — a shape that distinguishes it reliably from related species. Note that the name Tephrosia purpurea has historically been misapplied to the cultivated T. noctiflora, which differs in having longer inflorescences, a markedly elongated carinal calyx tooth, and reticulated seeds. The species is taxonomically variable and has been divided into several subspecies across its range.
What is Tephrosia purpurea used for in Ayurveda?
In the Ayurvedic system, Kathurupila is classified as pungent in taste and heating in its post-digestive effect (vipaka), making it useful for conditions associated with sluggish or obstructed organ function. Its most prominent traditional applications relate to the liver and spleen.
- Liver and spleen disorders: Considered a primary herb for hepatomegaly, splenomegaly, and liver cirrhosis in classical Ayurvedic texts.
- Digestive complaints: Roots are used in preparations for dyspepsia and chronic diarrhoea. Fresh root-bark ground into a pill and combined with black pepper is a traditional remedy for obstinate colic.
- Blood purification: The whole plant is used in formulations aimed at clearing skin conditions such as boils, pimples, eczema, and scabies; seed oil is applied topically for skin eruptions.
- Respiratory support: Taken internally for coughs and chest tightness associated with bilious febrile attacks.
- Antiparasitic use: Used in Sri Lanka as an anthelmintic for children. A decoction of roots has been documented as a nematicide for Toxocara canis larvae, which can cause pulmonary disease.
- Wound and bite care: A decoction of pounded leaves is applied externally for snakebites in some traditional communities.
- Cooling properties: Seed infusions are used as cooling preparations in parts of the Indian subcontinent.
In Indian classical medicine, the plant appears as a common ingredient in compound formulations targeting hepatitis, bilious fever, and splenic conditions. Its role in Sri Lankan traditional healing parallels these uses closely, reflecting the island's longstanding integration with broader South Asian medical traditions.
How is Tephrosia purpurea used in agriculture?
Beyond its medicinal role, the plant has long served practical purposes in tropical farming systems. Its nitrogen-fixing root nodules make it a valuable green manure crop, and it has been cultivated for this purpose in paddy fields across India for generations. Because it grows quickly in disturbed or poor soils, it can improve soil structure and nutrient content ahead of rice planting — an environmentally sound practice aligned with traditional integrated farming on Sri Lankan rice paddies.
In parts of India and South Africa, the leaves serve as supplementary livestock fodder. Dry plant matter has historically been gathered as fuel in rural communities. The seeds have even been used as a coffee substitute, though this is an incidental use rather than a cultivated tradition.
What active compounds does Tephrosia purpurea contain?
The plant contains a group of compounds called rotenoids, most notably tephrosine. These are secondary metabolites common to the Fabaceae family and are responsible for several of the plant's bioactivities — both useful and hazardous.
Rotenoids are classified by the World Health Organization as moderately hazardous substances. They are mildly toxic to humans and other mammals when ingested in significant quantities, but are extremely toxic to insects and aquatic animals, particularly fish. This differential toxicity occurs because rotenoids are lipophilic molecules that are readily absorbed through fish gills and insect trachea, whereas absorption through the mammalian gastrointestinal tract is comparatively slow and limited.
This biochemical profile explains two traditional non-medicinal uses of the plant:
- Fish stunning: Pounded leaves or plant material have been applied to still water to stun fish, making them easy to collect. Fish caught this way remain edible for humans.
- Insect repellent / insecticide: The plant has been used to repel or kill insects, a use consistent with the high insect toxicity of rotenoids.
It is important to note that while traditional uses involving fish poisoning are well documented, rotenoid compounds are environmentally persistent and their use in waterways raises legitimate ecological concerns. Modern sustainable practice discourages indiscriminate use of plant-based ichthyotoxins in open water systems.
Where does Tephrosia purpurea grow in Sri Lanka?
Kathurupila is a widespread pioneer species in Sri Lanka, found from coastal lowlands up through the dry and intermediate zones. It colonises roadsides, scrubland, forest margins, and degraded agricultural land readily, and is also cultivated in home gardens and Ayurvedic herb gardens. The plant is particularly well represented in the dry zone provinces, where traditional medicine remains an important part of community healthcare.
Collectors harvest both roots and aerial parts, with roots typically dug during the dry season when concentrations of active compounds are generally highest. Cultivated stands are sometimes established close to Ayurvedic hospitals and processing facilities to ensure a reliable supply of plant material of known provenance.
How does Tephrosia purpurea fit into Sri Lanka's Ayurvedic tradition?
Sri Lanka has one of the world's oldest continuous traditions of herbal medicine, with Ayurveda formally recognised alongside Western medicine in the national healthcare system. Kathurupila occupies a documented place in the Sri Lankan pharmacopoeia and appears in classical Sanskrit texts that have informed local practitioners for centuries.
The herb is frequently used in compound preparations alongside other botanicals — an approach consistent with Ayurvedic philosophy, which tends to combine synergistic plants rather than use single-herb extracts. Formulations targeting the liver, for example, may combine Kathurupila with Pongamia pinnata and other hepatoprotective herbs into a single decoction or pill. In this sense, understanding Tephrosia purpurea means understanding it not as an isolated remedy but as one element within a broader, integrated pharmacological system.
Is Tephrosia purpurea safe to use?
Used in the doses and preparations recommended by a qualified Ayurvedic practitioner, the plant has a long history of human use without documented systemic toxicity at therapeutic levels. However, self-medication at high doses or with crude preparations is not advisable. The rotenoid content means that excessive ingestion can be harmful, and the plant should not be administered during pregnancy without professional guidance.
Externally applied preparations — such as seed oil for skin conditions — carry a lower risk profile and have a well-established track record in traditional practice. Anyone seeking to use this herb therapeutically is advised to consult a registered Ayurvedic physician rather than relying solely on folk knowledge.