Ocimum Sanctum (Tulsi): A Comprehensive Review of Its Botanical, Phytochemical, And Pharmacological Profile

Abstract

Ocimum sanctum Linn., commonly known as Tulsi or Holy Basil, is a sacred and highly esteemed medicinal herb in Indian culture and traditional healthcare systems, particularly Ayurveda. Revered for its spiritual significance and therapeutic potential, Tulsi is widely cultivated across the Indian subcontinent. This review highlights the botanical, phytochemical, pharmacological, and traditional aspects of Tulsi, emphasizing its relevance in contemporary medicine. The plant is rich in bioactive compounds such as eugenol, ursolic acid, and flavonoids, which contribute to its diverse pharmacological properties, including antimicrobial, antioxidant, anti-inflammatory, anticancer, anti-diabetic, and adaptogenic effects. The article also explores the traditional uses of Tulsi in various Indian languages and regions, its taxonomic classification, and its botanical characteristics. Extensive scientific research supports the efficacy of Tulsi in managing conditions like respiratory disorders, metabolic syndrome, infections, and stress-related ailments. Given its wide range of therapeutic benefits and cultural importance, Ocimum sanctum continues to be a valuable resource in integrative and traditional medicine systems.

Keywords

Introduction

Tulsi (Ocimum sanctum), commonly known as Holy Basil, holds a significant place in the Hindu religious tradition and Indian culture [1]. The name 'Tulsi' signifies 'the incomparable one', while another of its names, Vishnupriya, refers to its divine association as ‘the beloved of Lord Vishnu’. Tulsi is commonly grown in Indian households and is deeply rooted in the country’s spiritual and medicinal heritage. Belonging to the family Lamiaceae, it exists in two main varieties-Rama (light) and Krishna (dark) Tulsi the latter being more commonly used in worship and known for its superior medicinal value [1][2].

This sacred plant is renowned not only for its religious significance but also for its wide array of therapeutic applications. Described in Ayurvedic texts and recognized in modern research, Tulsi exhibits a range of pharmacological activities such as antimicrobial, immunomodulatory, anti-inflammatory, anti-asthmatic, hypoglycaemic, hypotensive, antipyretic, and analgesic properties [1, 2]. Its parts are extensively used in treating a variety of conditions including bronchitis, liver disorders, skin diseases, and stress-related disorders [1].

Plants, in general, have been primary sources of medicine since ancient times. The use of medicinal plants has been recorded in early texts such as the Rigveda and is considered the foundation of Ayurveda, the traditional Indian system of medicine [2, 3]. Medicinal plants are rich in secondary metabolites and essential oils that possess significant therapeutic potential. Their use is preferred due to their relative safety, affordability, and wide availability [2, 3]. Examples include morphine from Papaver somniferum, ephedrine from Ephedra vulgaris, and ashwagandha from Withania somnifera [3].

Figure 1: Tulsi (Ocimum Santuon)

India is home to approximately 15% of the world's medicinal plants, with around 3000–3500 species being utilized in different systems of medicine and local healing practices [4]. According to a 1993 WHO survey, traditional medicine practitioners treat around 80% of patients in India, 85% in Burma, and 90% in Bangladesh, highlighting the enduring relevance of medicinal plants like Tulsi in primary healthcare [3, 4].

Synonyms Name of tulsi in Indian Languages [5][6]

Botanical Description of Tulsi (Ocimum sanctum Linn.)

• Habit and Habitat:

Ocimum sanctum (Tulsi) is an erect, branched, aromatic herb or small shrub growing up to 30–75 cm tall. It is native to the Indian subcontinent and widely cultivated in Southeast Asia. Tulsi grows well in tropical and subtropical climates and prefers moist, well-drained soil in sunny locations [8][9].

• Stem:

The stem is quadrangular (four-angled), slightly woody at the base, and covered with soft hairs. It has opposite decussate branching [9].

• Leaves:

                    Leaves are simple, opposite, and ovate to oblong with entire or serrate margins. They are 2–5 cm long and strongly aromatic due to the presence of essential oils [9]. The three main varieties are:

• Rama Tulsi – green leaves with a mild aroma
• Krishna Tulsi – purplish leaves with a stronger taste
• Vana Tulsi – green, wild variety with a more clove-like scent [10][11]

• Flowers:

Flowers are small, purplish or pink, and arranged in terminal racemes. They are bilabiate and zygomorphic, with five-lobed calyx and corolla. Each flower has four didynamous stamens and a bifid stigma.[10].

• Fruits and Seeds:

The fruit is a dry nutlet (schizocarp), splitting into four one-seeded parts. Seeds are yellow to brown and become mucilaginous when wet, aiding germination [11][12].

• Root:

Tulsi has a taproot system that penetrates deep into the soil, providing structural support and nutrient absorption [10]

Figure 2; leaves of Tulsi

Figure 3: Flowers of Tulsi

Phytochemical Constituents of Ocimum sanctum (Tulsi)

The leaves of Ocimum sanctum (Tulsi) contain 0.7% volatile oil comprising about 71% eugenol and 20% methyl eugenol. The oil also contains carvacrol and sesquiterpine hydrocarbon caryophyllene. Fresh leaves and stem extracts yield phenolic compounds (antioxidants) such as cirsilineol, circimaritin, isothymusin, apigenin, and rosameric acid, along with appreciable quantities of eugenol [1][3][7]

Additionally, two flavonoids—orientin and vicenin—have been isolated from aqueous leaf extract of Ocimum sanctum (Paragraph 2). Other compounds reported include ursolic acid, apigenin, luteolin, apigenin-7-O-glucuronide, luteolin-7-O-glucuronide, orientin, and molludistin [7]. The essential oil is mainly concentrated in the leaf and consists largely of phenols, terpenes, and aldehydes, which contribute to its distinct aromatic odour [1]

Besides volatile oils, the plant also contains alkaloids, glycosides, saponins, tannins, ascorbic acid, and carotene. It further contains a number of sesquiterpenes and monoterpenes such as bornyl acetate, β-elemene, neral, α- and β-pinenes, camphene, as well as sterols including campesterol, cholesterol, stigmasterol, and β-sitosterol [1][3][13]

Pharmacological Activities of Ocimum sanctum (Tulsi)

• Anti-Cancer activity

Cancer has emerged as a leading cause of death in developing countries due to changing lifestyles, food habits, and the decline of infectious diseases through curative treatments. Conventional cancer treatments such as surgery, radiotherapy, and chemotherapy are often expensive, invasive, and associated with severe side effects and frequent relapses. In contrast, Ayurveda offers several medicinal plants with anticancer potential. Studies have shown that ethanolic extract of Ocimum sanctum significantly reduces tumor cell size and increases lifespan in mice with Sarcoma-180 and Lewis lung carcinoma models. Compounds like ursolic acid and oleanolic acid found in Ocimum contribute to its anticancer effects and its ability to protect DNA from harmful radiation [[2][14].

• Anti-Oxidant activity

Ocimum sanctum L. exhibits significant antioxidant activity in both in vivo and in vitro studies. Phytochemical investigations of its leaf extract reveal phenols (eugenol, cirsilineol, isothymucin, apigenin, and vicenin) and flavonoids (orientin and vicenin), which possess potent antioxidant and cyclooxygenase inhibitory activities [15] Oral administration of Ocimum sanctum provides liver and aortic tissue protection from hypercholesterolemia-induced peroxidative damage. Additionally, studies have shown that Ocimum sanctum reduces plasma levels of thiobarbituric acid reacting substances and improves antioxidant enzyme status in vital organs like the liver and kidney in diabetic rats. Its hydroalcoholic extract also demonstrates antioxidant activity in animal models of peptic ulcer by decreasing malondialdehyde levels and increasing superoxide dismutase levels, suggesting a correlation between its antioxidant and antiulcer activities [6][15].

• Anti-Oxidant activity

Ocimum sanctum L. exhibits significant antioxidant activity in both in vivo and in vitro studies. Phytochemical investigations of its leaf extract reveal phenols (eugenol, cirsilineol, isothymucin, apigenin, and vicenin) and flavonoids (orientin and vicenin), which possess potent antioxidant and cyclooxygenase inhibitory activities [15]. Oral administration of Ocimum sanctum provides liver and aortic tissue protection from hypercholesterolemia-induced peroxidative damage. Additionally, studies have shown that Ocimum sanctum reduces plasma levels of thiobarbituric acid reacting substances and improves antioxidant enzyme status in vital organs like the liver and kidney in diabetic rats. Its hydroalcoholic extract also demonstrates antioxidant activity in animal models of peptic ulcer by decreasing malondialdehyde levels and increasing superoxide dismutase levels, suggesting a correlation between its antioxidant and antiulcer activities [6][15].

• Anti-Inflammatory activity

The Ocimum sanctum oil was found to be lacking in analgesic activity in experimental pain models such as tail flick, tail clip, and tail immersion methods. However, it was effective against acetic acid-induced writhing method in mice in a dose-dependent manner, with its writhing inhibiting activity suggested to be peripherally mediated due to combined inhibitory effects of prostaglandins, histamine, and acetylcholine [7][16].

• Anti-Microbial activity

Ocimum sanctum extracts show broad antibacterial activity. Its aqueous extract (AqE) inhibits Klebsiella, E. coli, Proteus, and S. aureus, while the alcoholic extract (AlE) is effective against Vibrio cholerae and multidrug-resistant S. aureus and Neisseria gonorrhea[17]. The fixed oil, rich in linolenic acid, also shows strong activity against Bacillus pumilus, Pseudomonas aeruginosa, and S. aureus [18].

• Anti-Bacterial activity

Tulsi (Holy Basil) shows strong antibacterial activity due to compounds like eugenol, carvacrol, and ursolic acid. Its extracts are effective against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and others. Ethanolic extracts and essential oils are particularly potent, supporting Tulsi’s traditional use in treating infections [19][20][22].

• Anti-Diabetic activity

Ocimum sanctum has been reported to possess significant anti-diabetic properties, with studies showing that its hydroalcoholic and ethanol extracts can reduce hyperglycemia in streptozotocin and alloxan-induced diabetic rats [22]. The extract has been found to have insulin-secretory effects on the rat pancreas and isolated rat islets, and oral administration of Ocimum sanctum extract has led to marked lowering of blood sugar in glucose-fed hyperglycemic and streptozotocin-induced diabetic rats [15][22]. The constituents of Ocimum sanctum leaf extracts have stimulatory effects on physiological pathways of insulin secretion, which may underlie its antidiabetic action [15]. Additionally, Ocimum sanctum has been shown to decrease serum concentrations of cortisol and glucose and exhibit antiperoxidative effects, suggesting its potential in regulating corticosteroid-induced diabetes [15].

CONCLUSION

Tulsi (Ocimum sanctum Linn.), revered in Indian tradition for its spiritual and medicinal value, stands as a remarkable example of a plant that bridges ancient wisdom and modern science. Its rich phytochemical profile, including essential oils, flavonoids, and phenolic compounds, underpins a wide range of pharmacological activities such as anti-cancer, antioxidant, anti-inflammatory, antimicrobial, and antidiabetic effects. These therapeutic potentials have been validated through both traditional Ayurvedic practices and contemporary biomedical research. As global interest in natural and plant-based remedies continues to rise, Tulsi offers a promising, accessible, and holistic option for managing various health conditions. Further in-depth research and clinical validation can help integrate Tulsi more effectively into modern healthcare systems, reinforcing its role as a cornerstone of both preventive and therapeutic medicine.

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