Murraya koenigii – Curry Leaf Tree

Common Names: Curry Leaf Tree, Curry Leaves, Sweet Neem, Murraya koenigii, Bergera koenigii, Indian Curry Leaf, Karapincha (Sinhala), Kari Patta (Hindi/Urdu), Noroxyle, Kaloupilé (French), Curryblattbaum (German), Curry Leaf (Global), Koenig's Murraya, Koenig's Bergera

Latin Name: Murraya koenigii

Origin: Asia

Short Introduction

For successful sowing, seeds must be mature and fresh. The entire berry can be planted, or the pulp removed and the seed set in a pot and kept moist. Curry leaf trees can also be propagated by stem cuttings.

The Curry Leaf Tree is heat-loving and, in temperate climates, is commonly grown as a container plant. Use sandy-loam, well-draining soil with drainage material at the base of the pot. Water only when the soil is dry, as excessive moisture is harmful. The plant thrives in sun or partial shade, and temperatures should never fall below 12°C, with an optimal range between 18–25°C.

Detailed Description

The Curry Leaf Tree is a staple spice from India, renowned for its surprising healing effects.

Botanical Information

Murraya koenigii, commonly known as the Curry Leaf Tree, is an aromatic shrub or small tree that can reach up to 6 meters in height with a trunk diameter of up to 40 cm. Its shoots are hairy, and its leaves are alternate, pinnately compound, petiolate, ovate, about 5 cm long and 2 cm wide, slightly serrated and pointed at the tip. The plant produces small, white, aromatic, five-petaled flowers aggregated in multi-flowered terminal panicles. The fruit is an ovoid or ellipsoid berry, up to 2 cm long, turning black when ripe and containing 1–2 seeds. The pulp of the berry is edible, sweet, and soft.

Origin and Distribution

The Curry Leaf Tree originates from the Indian subcontinent and likely Southeast Asia. It grows wild along the southern foothills of the Himalayas from Pakistan to southern China. Its distribution extends to southern India, Sri Lanka, Thailand, and Vietnam. Today, commercial plantations are found mainly in India and Australia.

Usage / Dosage

Fresh curry leaves are an essential component in Indian cuisine and traditional Indian preparations. They are especially popular along the southern and western coasts of India, commonly fried with vegetable oil, mustard seeds, and chopped onion. In Cambodia, where they are called sloek kontroap, the leaves are roasted and included in Mayu Krueng soup. In Java, they are steamed as a seasoning for gulai dishes. The essential oil can also be used for making fragrant soaps.

Essential oils and powder made from fresh curry leaves are used to flavor foods and ready-to-eat dishes. Due to the antimicrobial activities of the essential oil, curry leaves are used in traditional practices as natural flavor additives and perfumes. Fresh curry leaves may be boiled with coconut oil to create a hair tonic.

Traditional Medicine

Curry leaves play an important role in Ayurvedic medicine. Various parts of the plant—including leaves, roots, bark, and fruits—display a spectrum of biological effects. The leaves, slightly bitter in flavor and with a pungent aroma, are traditionally used as anthelmintics, analgesics, and digestives in both folk medicine and cuisine. Fresh leaves are also used to treat inflammation, itching, wounds, dysentery, bruising, and swelling. Roots are traditionally used for moderate stimulation and pain management. The bark is valued for snakebite, while the leaves are used as anti-diarrheal, antifungal, blood purifying, anti-inflammatory, and antidepressant remedies. Leaves and roots are also recommended as antipyretics and to relieve swelling and itching.

Antioxidant Activity

The essential oil from curry leaves has demonstrated antioxidant, hepatoprotective, antimicrobial, antifungal, anti-inflammatory, and nephroprotective effects in animal models. Natural antioxidants from plant sources such as curry leaves are considered promising adjuvant therapies for preventing and managing a range of conditions, especially neurodegenerative and cardiovascular diseases, and cancer. Bioactive compounds present include mahanine, mahanimbine, isolongifolene, koenimbine, girinimbine, isomahanine, koenoline, and O-methylmurrayamine, all with notable antioxidant properties.

Extracts of curry leaves have demonstrated high antioxidant activity in free radical scavenging tests, comparable to quercetin and vitamin C. Additional studies compared antioxidant effects to tannins and other well-known antioxidant compounds. Recently, extracts have been shown to protect against diabetes-induced oxidative stress, reduce lipid peroxidation, and protect the liver against ethanol-induced toxicity.

Anti-Inflammatory Activity

Ethanol extracts of curry leaves have significant analgesic and anti-inflammatory effects, as confirmed in animal models. Key bioactive components such as girinimbine, murrayakonin A, O-methylmurrayamine A, and mukolidin are associated with anti-inflammatory properties, particularly through modulating cytokine activity.

Antifungal and Antibacterial Activity

Curry leaf extracts show notable antifungal and antibacterial properties against a wide range of pathogens, including Penicillium notatum, Aspergillus flavus, Aspergillus niger, and Fusarium moniliforme. Active constituents such as alkaloids, terpenoids, flavonoids, phenols, tannins, and saponins are responsible for these antimicrobial effects. These properties explain the traditional use of curry leaves in treating diarrhea, dysentery, and skin eruptions. Extracts are effective even against Mycobacterium species, and synergistic effects have been observed with standard antimicrobials.

Hepatoprotective and Nephroprotective Effects

Curry leaf extracts have been shown to offer significant protection in animal models of liver damage caused by ethanol and in experimental models of kidney injury, maintaining near-normal levels of antioxidants, protein, and kidney function indicators.

Anti-Diabetic Effect

Alkaloids in curry leaves inhibit alpha-glucosidase and help reduce blood glucose, mimicking insulin actions and exerting antioxidant effects.

Anti-Cancer and Apoptotic Effects

The plant contains secondary metabolites with potential as anti-cancer agents, showing cytotoxic activity in cancer cell lines and animal models. Constituents induce apoptosis (programmed cell death) in cancer cells, and compounds such as mahanine, isomahanine, and girinimbine inhibit tumor growth and promote apoptosis in various cancer types, including oral, colon, breast, and liver cancers.

Neuroprotective Effects

Supplementation with curry leaf extracts has beneficial effects on neurodegenerative diseases such as Alzheimer's and Parkinson's, supports memory, and stabilizes antioxidant enzyme levels.

Active Compounds

Curry leaves contain cinnamaldehyde and numerous carbazole alkaloids like mahanimbine, girinimbine, and mahanine. They are also nutritionally rich in carotenoids, beta-carotene, magnesium, sodium, calcium, and iron; significant vitamin sources include A (beta-carotene), B1, B3, and other micronutrients.

Traditional Dosage

In preclinical studies, extracts were dosed at 100–400 mg/kg. In cuisine, curry leaves and blends are typically used at 1–2 tablespoons per kilogram of meat, vegetables, or per 500 grams of rice or similar dishes.