The Nigerian curry leaf, also known as lemon basil, with the botanical name, Murraya koenigii, is a tropical to sub-tropical tree in the family Rutaceae. It is a flowering plant, with a rich, sweet, pungent aroma. The local names are efirin oso in Yoruba and marugbo sanyan in Hausa.
Curry leaves are packed with carbohydrates, fibre, calcium, phosphorous, irons and vitamins A, B, C, E, carotene, nicotinic acid, iron and folic acid and amino acid. They also contain phenols, saponins and alkaloids like carbazole. The pungent aroma is because of the presence of an aromatic compound in it called Linalool/methylchavicol/1,8-cineole.
Curry leaves are commonly used as a seasoning ingredient to enhance the taste and flavour in almost every dish, such as stews, soup, jollof rice and noodles. Curry leaves may be used orally or topically as fresh whole or crushed leaves, as juice, dry powder, paste, tea or decoction. It may be used alone or in combination with other herbs.
Pharmacological actions and medicinal uses
Curry leaves are known for their curative properties and are used in Ayurveda as a natural treatment for various health problems. Packed with vitamin C, A and compounds such as kaempferol that is a very potent anti-inflammatory, anti-bacterial, anti-fungal, decongestant and anti-oxidative agent, curry leaves are a very effective home remedy for the treatment of wet coughs and chest congestion.
Carbazole alkaloids, with anti-bacterial and anti-inflammatory properties, are present in curry leaves and are responsible for a lot of the pharmacological actions reported for the plant.
Several studies have reported the effectiveness of various preparations of curry leaf in the management of upset stomach, morning sickness, peptic ulcers, diarrhoea, dysentery, wounds, skin eruptions, itchy skin, boils and burns.
Studies have also reported the effectiveness of curry leaf in burning unwanted fat, thus promoting weight loss, reduction of cholesterol, and cleansing the body by flushing out harmful toxins from the body. A variety of studies have demonstrated that the phenols and carbazole alkaloids in curry leaves have anticancer potential that can help protect the body from a variety of cancers like colorectal cancer, leukaemia, and prostate cancer. Consumption of curry leaves also reduces the effects of chemotherapy and radiotherapy, offers protection against chromosomal damage and safeguards bone marrow.
According to various researches, curry leaves can protect and stimulate insulin-producing cells of the pancreas from free radical damage thereby promoting blood sugar lowering.
Curry leaves are believed to help in strengthening hair roots, treating damaged hair and preventing greying and falling of hair, as well as treating dandruff. This may be achieved by applying the paste of curry leaves or the dry curry leaf powder mixed with oil to the hair.
Research on curry leaves has revealed that they are also effective in fighting bacterial and fungal infections. The leaf extracts from the plant have been comparable to popular mainstream antibiotic drugs.
Curry leaves should be avoided if one is allergic to it. A trained medical practitioner should be consulted prior to usage by pregnant, breastfeeding women and toddlers. Agricultural scientists have warned that the commercially-cultivated curry leaves are laced with poisonous pesticides that are harmful to health and lead to cancer in the long run.
Economic uses and potentials
Fresh curry leaves cost about ₦100-₦400 per bunch in the Nigerian market, while dry curry leaves cost as much as ₦1,750 – ₦2,500 per pack of 100g. There are potentials for this plant in cultivation, distribution and sales, as well as in the food, pharmaceutical and cosmetics industries.