A Review on Murraya Koenigii: Multipotential Medicinal Plant

Abstract

Murraya koenigii, commonly known as the curry leaf plant, is a significant medicinal and culinary herb native to South Asia. This review explores its phytochemical properties, traditional uses, pharmacological effects, and potential therapeutic applications. The plant is rich in various bioactive compounds, including carbazole alkaloids, flavonoids, terpenoids, and phenolic acids, which contribute to its diverse biological activities. M. koenigii exhibits remarkable antioxidant, anti-inflammatory, antimicrobial, antidiabetic, hepatoprotective, and anticancer properties, making it a promising candidate for natural drug development. In traditional medicine systems like Ayurveda and other folk practices, it has been utilized for treating gastrointestinal issues, skin infections, diabetes, and disorders related to oxidative stress. Recent studies have also highlighted its neuroprotective, cardioprotective, and immunomodulatory effects. Overall, this review emphasizes the therapeutic value of M. koenigii and its potential role as a crucial resource in the development of pharmaceuticals and nutraceuticals in the future.

Keywords

Introduction

Since ancient times, plants have played a vital role in traditional medicine due to their therapeutic properties. India, known as the "Botanical Garden of the World," boasts a vast diversity of medicinal herbs [1]. The practice of using medicinal plants for healing dates back to the beginning of human civilization, providing a natural source of curative compounds. Over the centuries, these natural agents have significantly contributed to the development of numerous modern pharmaceuticals. Recently, there has been a notable shift towards herbal medicine as an alternative to conventional treatments. This trend can be attributed to the affordability of plant-based remedies, which are often more accessible than expensive modern healthcare options for economically disadvantaged populations. Additionally, herbal medicines are commonly viewed as safer, with fewer side effects, and have shown effectiveness in treating a variety of infectious diseases [2]. Murraya koenigii, commonly known as curry leaf or karipatta in various Indian languages, belongs to the Rutaceae family, which encompasses over 150 genera and around 1600 species [3]. Vitamins C, B, E, and A are abundant in this plant. Curry leaves are a good source of folic acid and iron, which fight anemia [4]. This plant's leaves are commonly used in Indian cooking, and P-gurjunene, P-caryophyllene, P-elemene, and O phellandrene2 are the chemical compounds that give them their distinctive aroma. Whether alone or in combination, the presence of -pinene, -caryophyllene, -phellandrene, and -pinene can prevent food from spoiling [5]. Among fourteen global species belonging to the genus of Murraya, only Murraya koenigii Spreng and Murraya paniculata (Linn) are available in India [1]. Herbal medicines are becoming increasingly popular among many people because they are often seen as affordable, safe, and effective for treatment. In India, Murraya koenigii, better known as Kadhi Patta or curry leaves, is a significant medicinal herb that serves both as a flavourful spice in cooking and as a remedy for various health issues. Its unique flavor has made it a key component in Indian dishes, incorporated regularly into daily meals. Nutritionally, curry leaves are packed with vital vitamins, including C, A, B, and E, as well as nicotinic acid. They also boast a range of beneficial phytochemicals such as plant sterols, antioxidants, flavonoids, and glycosides. Additionally, these leaves are rich in proteins, dietary fiber, and essential minerals like phosphorus, iron, calcium, magnesium, and copper, along with carbohydrates [5].

Taxonomical Classification:  

 Murraya koenigii is systematically classified within the Plantae kingdom and Tracheobionta subkingdom, consisting of vascular plant species. As part of the Spermatophyta superdivision, it is categorized as a seed-bearing plant, and its classification within the Magnoliopsida division denotes its identity as a dicotyledonous angiosperm. This species is also included in the Rosidae subclass, which is known for a diverse range of flowering plants. Within the Rutaceae family, commonly referred to as the rue or citrus family, M. koenigii falls under the genus Murraya. This genus was named in tribute to Johann Gerhard König, an 18th-century botanist instrumental in its taxonomic recognition. Among the different species within the Murraya genus, M. koenigii is particularly noteworthy due to its extensive medicinal uses and unique aromatic properties [6].

Figure 1: Murraya Koenigii Plant

Distribution:  

Murraya koenigii, commonly known as the curry leaf plant, is native to South Asia and thrives in countries such as Vietnam, Sri Lanka, Nepal, Indonesia, China (particularly Hainan and Yunnan), India, Laos, Thailand, Bhutan, and Pakistan. In India, it is especially abundant in regions like the Andaman Islands, Sikkim, West Bengal, Assam, the Western Ghats, and Garhwal [7]. The plant typically propagates through seeds, which germinate readily in partially shaded conditions. It grows in diverse Asian environments, including humid forests at elevations between 500 and 1600 meters, such as those in South Hainan, South Yunnan (Xishuangbanna), Guangdong, Bhutan, Thailand, Laos, Nepal, Pakistan, Sri Lanka, and Vietnam. Due to migration, curry leaves were introduced to Malaysia, South Africa, and Réunion Island by South Indian immigrants. However, the species is rarely found outside its native range in South Asia [8].

Physical Description and Structural Features:

Murraya koenigii is a small, bushy shrub that typically grows up to 2.5 meters tall. Its stem exhibits a dark green to brownish hue, and when the bark is peeled longitudinally, it reveals an underlying white wood. The main stem has an average diameter of approximately 16 cm. The plant features compound leaves measuring about 30 cm in length, each consisting of 24 leaflets with a distinct reticulate venation pattern. Its flowers are white, funnel-shaped, and emit a pleasant aromatic fragrance. A fully bloomed flower averages 1.12 cm in diameter and is bisexual. The fruits are oblong to spherical, ranging from 1.4 to 1.6 cm in length and 1 to 1.2 cm in diameter. When fully ripe, they turn glossy dark with a wisteria-blue pulp. Each fruit contains a spinach-green seed measuring about 11 mm in length and weighing approximately 445 mg [9].

Phytoconstituents of Plant:

1. ROOT:

The roots of Murraya koenigii are noted for containing several bioactive compounds, including marmesin-1”-O-rutinoside, murrayagetin and Murrayanol. The bark is also rich in unique phytochemicals, producing three monomeric and five dimeric carbazole alkaloids: mukoenine-C, mukoenine-A, mukoenine-B, bis-2-hydroxy-3-methyl carbazole, bismurrayaquinone-A, bismahanine, bikoeniquinone-A, and murrastifoline-F. Additionally, benzene extracts from the roots yield further alkaloids, mukolidine and mukoline, emphasizing the extensive phytochemical profile of this remarkable plant. These compounds contribute significantly to the therapeutic potential of Murraya koenigii in various medicinal applications.

Figure 2: Murraya Koenigii Root

2. LEAF:

The leaves of Murraya Koenigii contain several bioactive compounds, including isomahanine, bispyrayafoline, O-methylmurrayamine, koenimbine, and bismahanine. Additional significant phytochemicals present are murrayacine, isomahanimbicine, isomahanimbine, koenigine, koenine, and koenidine. Dried leaves have been found to contain 6-dimethoxy-1-hydroxy-3-methyl carbazole, 1-formyl-3-methoxy-6-methyl carbazole, and glycozoline. Beyond these secondary metabolites, the leaves are also nutritionally valuable, being rich in nicotinic acid, minerals, carotene, proteins, and dietary fibre [10].

Figure 3: Murraya Koenigii Leaf

3. SEED:

The seeds of Murraya koenigii (curry plant) contain 4.4% total lipids, primarily composed of neutral lipids (85.4%), glycolipids (5.1%) and phospholipids (9.5%). The lipid profile includes 10.2% free fatty acids, 73.9% triacylglycerols, and minor amounts of monoacylglycerols, diacylglycerols and sterols. Additionally, the seeds contain terpenes, phospholipids, alkaloids, furocoumarin lactone, carbazole, and glycolipids. Among the bioactive compounds in the plant extract, the alkaloid mahanine is particularly notable due to its potent pharmacological properties. These alkaloids are recognized for their diuretic, antioxidant, antidiarrheal, anti-inflammatory, and antitumor effects [11].

Figure 4: Murraya Koenigii Seeds

Pharmacological Activities:

Figure 5: Pharmacological Activities

1] Hepatoprotective Effect:­

The protective nature of M. koenigii leaves extract was studied by Gupta et al.2007. The effects were attributed to the combined action of carbazole alkaloids Mahanine, Mahanimbine, ascorbic acid, Girinimbine, Murrayazolidine, Isomahanimbine, and minerals (Zn, Cu, Fe), along with murrayazoline found in the leaf extract. This study established M. koenigii as a promising and rich source of free radical quenchers, which exert their effects through hepatocyte membrane stabilizing activity and the reduction of fat metabolism [12]. Normal cell morphology was maintained after an ethanolic challenge when an aqueous extract containing tannins and carbazole alkaloids from M. koenigii was administered. The hepatoprotective activity was evaluated through different parameters, and it was noted that normal morphology persisted even after the ethanol exposure, comparable to the protective effect of the standard drug L-ornithine-L-aspartate [13]. Additionally, the acetone extract of dried bark powder demonstrated significant protection of liver cells when compared to the control group and other solvents in CCl4-induced liver damage. solvents in CCl4-induced liver damage [14].

2]  Anticancer Activity:­

Extensive research has highlighted the remarkable anticancer potential of carbazole alkaloids derived from M. koenigii, which operate through diverse biological pathways. The bark-extracted compound girinimbine has been shown to effectively induce apoptosis in HepG2 liver cancer cells, while mahanine, another key alkaloid, specifically activates the extrinsic apoptosis pathway via death receptor signalling. Notably, mahanine demonstrates selective cytotoxicity, exhibiting potent activity against MOLT-3 lymphoblastic leukaemia cells while remaining non-toxic to K562 myeloid leukaemia cells. Further studies have isolated additional bioactive compounds, including murrafoline and pyrayafoline, along with three other carbazole alkaloids, all of which show significant cytotoxic effects against HL-60 promyelocytic leukemia cells. Among these compounds, mahanine has emerged as the most promising anticancer agent from M. koenigii, displaying particularly strong therapeutic potential for future drug development [15].

4] Nephroprotective Activity:

Studies have revealed the kidney-protective properties of M. koenigii in diabetic animal studies [16]. The leaf extract demonstrated remarkable efficacy in regulating key kidney function parameters, including normalization of blood urea nitrogen (BUN), urinary protein levels, and serum and urinary creatinine concentrations. It also helped maintain sodium balance and urine production volume. Further research showed that the extract preserved appropriate myeloperoxidase (MPO) enzyme activity, supported antioxidant defenses, and prevented structural damage to kidney tissue following ischemia-reperfusion injury, suggesting its potential for clinical application in kidney diseases [17].

Scientific investigations have established the nephroprotective potential of M. koenigii through various experimental models. The plant extract exhibited significant therapeutic effects by lowering key biomarkers of renal damage, such as lipid peroxidation (LPO), serum creatinine, and BUN levels. Treatment groups showed higher concentrations of endogenous antioxidants (superoxide dismutase and glutathione) compared to controls exposed to cyclophosphamide, indicating strong protection against drug-induced kidney injury [18]. In diabetic conditions, M. koenigii administration resulted in dose-responsive renal benefits, effectively reducing serum creatinine and urea concentrations while enhancing systemic antioxidant status. Histological assessments confirmed these biochemical improvements, showing preserved kidney architecture and signs of cellular regeneration, with aqueous extracts demonstrating particularly pronounced therapeutic effects [16].

5] Cardioprotective activity:­

Research has shown that Murraya koenigii (curry leaf) aqueous extract offers significant heart-protective effects in rat models exposed to cadmium. These cardioprotective benefits seem to be largely due to the extract's strong antioxidant properties. Cadmium toxicity has been observed to disrupt cardiac mitochondrial function, specifically impacting respiratory chain enzymes and the tricarboxylic acid cycle. Notably, prior administration of the M. koenigii extract was effective in reversing the metabolic disturbances caused by cadmium in cardiac tissue [19].

6]Antidiarrheal activity:

The bioactive alkaloids kurryam and koenimbine, isolated from the n-hexane fraction of M. koenigii seeds, demonstrated notable antidiarrheal and antimotility effects in Wistar rats. These compounds significantly inhibited both castor oil-induced diarrhoea and prostaglandin E2-induced intestinal fluid accumulation. Additionally, in the charcoal meal test, they markedly reduced gastrointestinal motility, suggesting potential therapeutic applications for managing diarrheal disorders [20].

7] Vasodilating Activities:

The rough fluid leaf concentrate of M. koenigii showed a dose-dependent negative chronotropic effect on the isolated frog heart, likely due to its direct action on cardiac tissue and blood vessels. Fire photometry analysis indicated negligible potassium ion levels, suggesting potassium was not involved in this effect. Additionally, the aqueous leaf extract demonstrated vasodilatory activity, which increased perfusion drop rates during frog hind limb experiments, and did so without engaging muscarinic, histaminergic, or β-adrenergic receptors, while also lacking α-adrenergic blocking activity. Notably, a concentration of 1 mg/ml produced a significant response. In a separate experiment, the crude ethanolic extract of fresh M. koenigii leaves exhibited a dose-dependent positive inotropic effect on the isolated frog heart. This effect continued even in the presence of substances like theophylline, imidazole, propranolol, and sildenafil, indicating these pathways were not involved. Moreover, variations in potassium and sodium concentrations had no impact, suggesting the positive inotropic effect may be attributed to increased extracellular calcium availability [21].

8] Antiviral properties:

Murraya koenigii contains several carbazole alkaloids, including o-methylmurrayamine A, mukonicine, girinimbine, and koenine. These compounds have garnered interest for their potential to inhibit SARS-CoV-2 replication. Computational studies indicate that they may block viral replication by interfering with the catalytic activity of the main protease, which is a crucial enzyme within the virus's life cycle [22].

9] Mosquitocidal and larvaecidal activity:

 Studies have demonstrated the larvicidal potential of Murraya koenigii leaf extracts against Aedes aegypti, the primary vector for dengue fever. Both petroleum ether and acetone extracts exhibited significant larvicidal activity [23]. Additionally, chloroform and methanol extracts derived from the stem bark of M. koenigii also displayed strong efficacy against Aedes aegypti mosquitoes [24].

10]  Memory enhancing:

The study demonstrated that the ethanolic extract of Murraya koenigii leaves had a notable impact on serum cholesterol levels in mice, leading to a significant reduction. Additionally, the extract was found to inhibit the acetylcholinesterase enzyme in the brain, which in turn resulted in increased levels of acetylcholine in brain homogenates. This enhancement in acetylcholine concentration correlated with improved memory function in aged mice. Two concentrations of the extract were tested (300 mg/ml and 400 mg/ml), and both exhibited these positive effects. The observed memory-enhancing properties are thought to arise from a dual mechanism involving both cholesterol reduction and acetylcholinesterase inhibition [21].

11]Anti-inflammatory:

Several extracts of Murraya koenigii were evaluated for their anti-inflammatory properties using established experimental models. The petroleum ether, chloroform, and ethanol extracts (250 mg/kg dose) were tested using the carrageenan-induced paw edema and yeast-induced hyperpyrexia methods. Among these, the ethanolic extract demonstrated the most significant anti-inflammatory effects [25]. Further investigation identified 9,12-octadecadienoic acid from the leaf' methanolic extract as a potent bioactive compound. At a concentration of 150 µg/mL, this compound exhibited remarkable anti-inflammatory activity, reducing paw edema by 85%, which was notably higher than the 68.62% reduction observed with standard aspirin under the same experimental conditions [26].

12]Anti-ulcer activity:

The aqueous extract of M. koenigii demonstrated notable anti-ulcer activity when tested at doses of 200 and 400 mg/kg. The study revealed that the extract effectively inhibited gastric lesions caused by non-steroidal anti-inflammatory drugs (NSAIDs) and pylorus ligation-induced ulcers. Key findings included a reduction in ulcerative lesions, decreased gastric volume, and lowered levels of both free and total acidity. Additionally, the extract increased the pH of gastric juice in the pylorus ligation model. These results strongly indicate that M. koenigii aqueous extract possesses significant anti-ulcer properties [27].

13]  Antioxidant Activity:

The aqueous leaf extract of M. koenigii demonstrated significant cardioprotective effects against cadmium-induced oxidative stress in rats, likely attributable to its potent antioxidant properties. This protective effect was observed in both environmental and occupational exposure scenarios. The study revealed cadmium-induced oxidative damage through several biochemical markers: increased lipid peroxidation, altered reduced glutathione levels, elevated protein carbonyl content, and significant changes in the activity of both antioxidant and pro-oxidant enzymes in cardiac tissue. These findings suggest that M. koenigii extract effectively counteracts cadmium's toxic effects on cardiac tissue through its antioxidant mechanisms [26].

Other uses:

1. The Murraya koenigii helps treat bruises, skin eruptions, and poisonous animal bites.
2. Fresh leaves, dried leaf powder, and essential oil from curry leaves are commonly used to flavor soups, curries, fish, meat, egg dishes, traditional spice blends, seasonings, and various ready-to-eat foods.
3. Incorporating dried curry leaf powder into regular dishes provides an additional source of essential micronutrients.
4. Adding curry leaf oil to your daily skincare cream or lotion can help treat various skin issues, including pimples, athlete’s foot, ringworm, itching, acne, boils, and infected wounds or burns, when applied to the affected area.
5. Formulations containing Murraya koenigii essential oil provide sun protection and reduce erythema.
6. Curry leaf oil promotes the contraction of muscles and tissues.
7. Curry leaf extract aids in improving skin pigmentation and diminishing white patches across the body [28].

CONCLUSION:

Murraya koenigii, is a valuable medicinal herb with a wide variety of phytochemicals and possible uses. Its historic applications in treating a variety of illnesses are supported by the antioxidant, anti-inflammatory, antibacterial, antidiabetic, and anticancer qualities that its bioactive components contribute. In order to bridge the gap between traditional knowledge and contemporary research, this review emphasizes M. koenigii as a potential resource for creating natural medicines and nutraceuticals.

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