Curry leaf - Chemical structure and Functional properties

Curry leaf

Introduction Curry leaf (Murraya koenigii Spreng) (Syn. Bergera koenigii Koen (N.O. Aurantiaceae), Chaleos koenigii Kurz ex Swingle) is a perennial leaf vegetable. It belongs to the family Rutaceae and is named Murraya after John Adam Murray, Professor of Botany at Gottingen and editor of many of Linnaeuss works. It is a native of the mountainous parts and grows up to an elevation of 0 m. The curry leaf is found growing throughout India including the Andaman Islands up to an altitude of m. It is recorded wild in Garwhal to Sikkim, Bengal, Assam, the Deccan, Circar mountains, Western ghats, Coromandel and Travancore Cochin. The leaves of the plant are used extensively for seasoning and flavouring dishes. Curry leaf is exported as curry leaf and as curry leaf oil from India (Table

The leaves of the plant are employed extensively as flavourant in curries like dal,

South Indian Sambar, rasam and chutneys and mulligatawny. Ground curry leaf with mature coconut kernel and spices forms an excellent preserve. Veppilakkatti, a very famous preparation of South India, can be made with the following ingredients: curry leaf (100 g); tender leaves of malta lemon (50 g); common salt (50 g); seedless tamarind (40 g); red chilli powder without seed (20 g); fenugreek powder (2 g); asafoetida (6 g); black pepper powder (2 g); gingelly oil (10 g). For preparing

Table 1 Export of curry leaf from India during 4 to 8 (quantity in tonnes, value in Rs.

Product  4 5 6 7

Qty Value Qty Value Qty Value Qty Value Qty Value

Curry leaf 2 7 9 8 0 4 6 1 8

Curry leaf oil 0.4 4

Source: Spices Statistics, IVth edition by Spices Board, Ministry of Commerce, Government of India, Cochin,

veppilakkatti, fry the asafoetida in gingelly oil and powder it. Mash the tender leaves of malta lemon in a mixi and remove all the fibres. Then add curry leaves, red chilli powder and other ingredients and grind well. If kept in airtight containers it can be stored for a long time.

Chemical structure

The leaves contain the following free amino acids: asparagine, glycine, serine, aspartic acid, glutamic acid, theonine, alanine, proline, tyrosine, tryptophan, amino butyric acid, phenylalanine, leucine, isoleucine, and traces of ornithine, lysine, arginine and histidine. The leaves also contain a crystalline glucocide, koenigin and a resin.

By analysis of concentrated essence of curry leaf, Macleod and Pieris² obtained mainly terpenes. They also found that M. koenigii produced less than 4% of other components with eight monoterpene hydrocarbons (Ca ) and seventeen sesquiterpene hydrocarbons (Ca 80%). According to them the most important constituents of M. koenigii are caryophyllene, -gurjunene, elemene, - phellandrene and -thujene.

Bhattacharya et al. reported a carbazole alkaloid-isomurrayazoline from M. koenigii with a structure of 9a,10,11 3,13a-hexahydro-5 2 tetramethyl-1, 2-epoxy-9H- indolo( de) phenanthridine C H NO . Alkaloids like muconicine, mahanimbine, koenimbine, koenigicine, cyclomahanimbine, mahanimbidine, girinimbine, iso- mahanimbine, murrayacine, mahanine, koenine, koenigine, koenidine and scopolin were reported by various workers.

From the stem of M. koenigii, a new C23-carbazole alkaloid, mahanimbinol, was isolated. It is the key precursor in the biosynthesis of some 0 other carbazole alkaloids. Bhattacharya et al. identified two carbazole alkaloids namely 2-methoxy carbazole-3- methyl carboxylate and 1-hydroxy-3-methyl carbazole from the stem bark extract of M. koenigii. From the stem bark, alkaloids like mahanimbinol, mukonal, murrayanine, murrayacinine and murrayazolidine were isolated and characterised by various workers.

The fruit is edible. It yields % of a yellow volatile oil with neroli-like odour and pepper-like taste, accompanied by an agreeable sensation of coolness on the tongue. The characteristics of the oil are as follows:

 specific gravity (13s) 0

 refractive index (0s) 1

 optical rotation (0s) .

 boiling point 173174s

The fruit is reported to contain koenigin. A yellow clear and transparent oil is procured from the seeds which is known as limbolee oil.

Chowdhury⁶ reported that leaves on hydrodistillation gave % essential oil on fresh weight basis, having dark yellow colour, spicy odour and pungent clove-like taste. It has the following characteristics:

 specific gravity (25s)

 refractive index (25s)

 optical rotation (25s) + 8

 saponification value

 saponification value after acetylation

 acid value

 soluble in % alcohol with slight opalescence

The constituents of the oil are:

 dl- -phellandrene

 d-sabinene

 d- -pinene

 dipentene

 d- -terpineol

 caryophyllene

 isosafrol

 cadinene

 cadinol

 lauric acid

 palmitic acid

On examination by GC-MS the oil contained aromadendrene, -bisabolene, butyl myristrate, carvomethone, cis-caryophyllene, -costol, citral, trans-caryophyllene, iso- caryophyllene, camphene, dehydro aromadendrene, dipentene, -elemene, -eudesmol, farnesol, junipene, linalyl acetate, isomenthone, menthol, spathulenol, stearyl alcohol, ateraldehyde, stearic acid, -terpineol, palmitic acid, -pinene and zingiberene.

The essential oils hydrodistilled from leaves of Murraya koenigii were analysed by GC and GC-MS. Both essential oils contained mainly monoterpenes and oxygenated monoterpenes. The main constituents are -pinene 9 ), sabinene %

-pinene 4 , terpinene , beta-phellandrene 5 , tauterpinene 7 ) and terpinen-4-01 9 . Madalageri et al. reported different compounds in the hydrodistilled essential oil out of which only seven were identified. A commercially important odouriferous compound -caryophyllene is among them.

Production

The leaves retain their flavour even after drying and hence these are marketed both in fresh and dried forms. There is not much loss of volatile oil during drying either in sun/ shade or in cross flow dryer. Oven drying at 50sC is recommended as the best technology for conversion of fresh leaves into dry powder.⁸ Higher temperatures during drying deteriorated powder quality.

Fresh leaves on steam distillation under pressure 0 lb/in yield 2.6% of a volatile oil

(curry leaf oil). According to Madalageri et al. hydrodistillation of fresh leaves at C is a cheap and non-cumbersome method of extraction of essential oil. Leaf maturity influenced oil composition, the youngest leaves tested being the best. An extended period of extraction caused loss/decrease in certain components while there was gain/increase in other components.

Functional properties

On analysis the leaves contain the following nutrients:

 moisture

 protein

 fat (ether extract)

 carbohydrate

 fibre

 mineral matter

 calcium 0 mg/1 0 g of edible portion

 phosphorus 0 mg/1 0 g of edible portion

 iron 1 mg/1 0 g of edible portion

 carotene (as vitamin A) 2 0 IU/100g

 nicotinic acid 3 mg/100g

 vitamin C 4 mg/100 g

 thiamine and riboflavin absent

The leaves are a fair source of vitamin A. They are also a rich source of calcium, but due to the presence of oxalic acid in high concentration (total oxalates, %; soluble oxalates, % , its nutritional availability is affected.

Curry leaf is used in traditional medicine, for example ayurvedic and unani medicine. ¹ The plant is credited with tonic, stomachic and carminative properties. The undiluted essential oil exhibited strong antibacterial and antifungal activity when tested on microorganisms. Even the crude leaf extracts of curry leaf plant are reported to possess antibacterial activity.

Curry leaf has a potential role in the treatment of diabetes. Hypoglycemic action on carbohydrate metabolism was reported in rats fed with curry leaves. ⁴ Hepatic glycogen and glycogenesis, as evident from the increased activity of glycogen synthetase, were increased and glycogenolysis and gluconeogenesis were decreased as evident from the decreased activity of glycogen phosphorylase and gluconeogenic enzymes.

Curry leaf is found to exert antioxidant properties in rats fed a high fat diet. There were lower levels of hydroperoxides, conjugated dienes and free fatty acids in the liver and heart of rats supplemented with curry leaves compared to rats fed on the high fat diet alone. Activities of superoxide dismutase, catalase and glutathione transferase were increased in the heart and liver of rats supplemented with curry leaves. Activities of glutathione reductase, glutathione peroxidase and glucose-6-phosphate dehydrogenase were also increased in the liver and the concentration of glutathione was decreased. Thus supplementing a high fat diet with % curry leaf can prevent the formation of free radicals and maintain the tissues at normal levels

Patel and Rajorhia reported that ghee samples treated with % curry leaves during clarification showed higher resistance to oxidation and higher sensory scores than those treated with a mixture of BHT (butylated hydroxy toluene) + BHA (butylated hydroxy anisole , due to the presence of naturally-occurring antioxidants. The curry leaves at 1% concentration could be used instead of BHT and BHA for extending the shelf-life of ghee.

References

. COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH The Wealth of India, New Delhi, CSIR, 1962 6

. MACLOED A J and PIERIS N M, Analysis of the volatile essential oils of Murraya koenigii and Pandanus latifolius , Phytochemistry, 2 1 ) 1

. BHATTACHARYA L, ROY S K and CHAKROVORTY D P Structure of the carbazol alkaloid isomurrayazoline from Murraya koenigii, Phytochemistry, 2 21

. RASTOGI R P and MEHROTRA B N, Compendium of Indian Medicinal Plants Vol. I-IV

New Delhi, Publication and Information Directorate, 9

. BHATTACHARYA P, MAITA A K, BASU K and CHOWDHURY B K, Carbazol alkaloids from

Murraya koenigii Phytochemistry, 4 5 )

. CHOWDHURY A R, Essential oil from the leaves of Murraya koenigii , National Seminar Research and Development in Aromatic Plants: Current trends in biology, uses, production and marketing of essential oils, Lucknow, Central Institute of Medicinal and Aromatic Plants,

. MALLAVAPURA G R, RAMESH S, SYAMASUNDAR K V and CHANDRASEKHARA R S

Composition of Indian curry leaf oil, J. Ess. Oil Res, 9 1 )

. MADALAGERI B B, MAHADEV and HIREMATH S M, Dehydration methods, oil extraction and flavour components detection in curry leaf (Murraya koenigii Spreng) and detection of flavour components, Karnataka J. Agri. Sci, 6 9 )

. DRURY H C, The Useful Plants of India, London, Allen,

. DASTUR J F Medicinal Plants of India and Pakistan, Bombay, Taraporevala Sons,

. KIRTHIKAR K R and BASU B D, Indian Medicinal Plants, Dehra Dun, Bishen Singh

Mahendra Pal Singh,

. GOUTAM M P and PUROHIT R M, Antimicrobial activity of the essential oil of the leaves of Murraya koenigii (Linn) Spreng (Indian Curry leaf), Indian J. Pharm.,

4 6 )

. THAKARE R P, Studies on the antibacterial activity of some plant extracts, Indian

Drugs 0 7 )

KHAN B A, ABRAHAM A and LEELAMMA S, Hypoglycemic action of Murraya koenigii

(curry leaf) and Brassica junceq mustard): mechanism of action, Indian J. Biochem. and Biophys., 5 2 )

. KHAN B A, ABRAHAM A and LEELAMMA S, Antioxidant effects of curry leaf Murraya koenigii and mustard seeds Brassica juncea in rats fed with high fat diet, Indian J. Exptl Biol , 97 5 )

. PATEL R S and RAJORHIA, Antioxidative role of curry (Murraya koenigii) and betal

(Piper betle) leaves in ghee, J. Food Sci. Technol, 9 6 )