by Luta Kora Mbaka
If you have ever sought herbal remedies against the all too common “brain fog”, it is highly probable that you came across Holy basil as an option to boost mental and brain health. Then, perhaps, you pleasantly discovered Holy basil is also listed as an ingredient in a multi-herb complex, targeting inflammation and pain. Upon further investigations, Dr Google unearthed that Holy basil can also be used to fight infections, including flu, bronchitis or common cold.
Indeed, Holy basil, also known as the Queen of Herbs in Ayurveda*, is associated with a plethora of medicinal applications, as well as perfumery and culinary uses. It is worth exploring the scientific basis and implications of Holy basil’s important applications viz. as a memory booster and anti-inflammatory and analgesic agent.
Popular History & Contemporary Use
Holy basil is an aromatic shrub related to the culinary herb Thai basil (Ocimum basilicum) and a member of the Lamiaceae family, which is an important family of flowering plants and herbs with significant medicinal contributions (Edwards et al., 2015; Sim et al., 2019). It is indigenous to the Himalayas in India as well as Taiwan, China, and parts of north and east Africa (WHO, 2002). Holy basil was introduced outside of native regions along trade routes primarily due to its medicinal and culinary uses, and reached Europe in the 16th century (Das & Vasudevan, 2006)
In Hindu cultures, Holy basil is sacred (indicative of its synonym Tulsi, the Hindu goddess of loyalty) and is cultivated around temples and places of worship and included in religious rituals and auspicious ceremonies, including rosary beads made from stems. The plant is often found in Hindu homes, even in modern era western countries, in dedicated south side courtyards where it is worshipped to increase religiousness, promote meditation, purify and protect (Petruzzello, 2019; D. Singh & Chaudhuri, 2018).
According to Ayurveda*, Holy basil has been used medicinally for more than three millennial years and is associated with hot and bitter taste characteristics (Cohen, 2014; Jamshidi & Cohen, 2017). The earliest documented uses against inflammation and pain date to 3500–1600 BCE, wherein it was recommended for severe headaches, and symptoms of arthritis amongst other illnesses (Uritu et al., 2018). It is also traditionally used against cough, malaria, diarrhoea, dysentery, skin diseases, painful eye, as an adaptogen and its essential oil is a well-known insect repellent (Cohen, 2014; Giridharan et al., 2015; D. Singh & Chaudhuri, 2018). In more recent times, it has been claimed as antifertility, anticancer, antidiabetic, antifungal, to protect against liver damage and cardiac disease, to relieve muscle spasms, and to induce perspiration (Kulkarni & Adavirao, 2018). Traditional preparations were typically decoctions of fresh leaves with hot water, although dried leaves or all plant parts could also be utilised, as were green leaves pastes and essential oils (Jamshidi & Cohen, 2017; D. Singh & Chaudhuri, 2018). Today, Holy basil is available in grocery stores as spice mixes and in health food stores as tea or food supplements to promote overall wellbeing, relieve stress, against asthma, allergies and respiratory tract infections or in pre- or post-menstrual remedies. It is also formulated in ayurvedic skin products such as exfoliants.
Biological Characteristics & Identification
Holy basil grows in the Medical Herb Spiral on the North East corner of Mecklenburg Square Garden, a private London Square garden. It is an annual, perennial shrub propagated by seed, cultivated up to 1800m above sea level and requiring moist soil, tropical and warm climate. It can reach up to 60 cm height at maturity; its small leaves are hairy, ovate with a clove-like fragrance; its flowers are violet or white, elongated in compact clusters, and its seeds are round yellow to brown (Kulkarni & Adavirao, 2018; Verma, 2016).
The taxonomical identification of the plant is often debated and ambiguous. Two varieties are recognised when referred to Holy basil: Ocimum tenuiflorum L. Rama (formerly Ocimum sanctum L.) and Ocimum tenuiflorum L. Krishna. O.t. Rama has green leaves and is generally preferred for religious purposes, whilst O.t. Krishna has purplish leaves and is preferred for medical uses. Both are differentiated from other Ocimum plants by their yellow pollen and smaller chromosome number (Jamshidi & Cohen, 2017; Jürges et al., 2018; Kulkarni & Adavirao, 2018). The related plant Ocimum gratissimum (synonyms: Vana Tulsi, African basil or wild Tulsi) is now accepted to be a separate species as established by DNA identification analysis (Jürges et al., 2018). Although chemically and morphologically different, O. t. Rama, Krishna and O. gratissimun were traditionally used alike to treat similar ailments (Jamshidi & Cohen, 2017) consequently, some authors do not differentiate the specific variety investigated, or more often cite the former name, O. sanctum, without clarifying if referring to O.t. Rama only. On the other hand, a chemical classification is sometimes adopted in publications, namely eugenol or methyl chavicol varieties; the former compound is not found in O. gratissimum (Khan et al., 2010; D. Singh & Chaudhuri, 2018). The ambiguity concerning taxonomy has several implications, including incorrectly attributing therapeutic benefits, overlooking safety consideration, and inadequate quality standards.
The chemical composition of Holy basil, predominately the leaves and seeds, has been extensively explored. The leaves contain essential and fixed oils, flavonoids (compounds associated with plant pigmentation), phytosterols (hormone-like compounds), fatty acids (long chain of hydrogen and carbon soluble in oil), and others (D. Singh & Chaudhuri, 2018). Limited information exists on the characterization of the physiologically active alkaloids (nitrogen containing compounds) present in Holy basil.
The essential oils yield (0.3-1.4%) and composition are heterogeneous based on plant variety, harvesting, and geographical conditions. The essential oils typically contain the compounds eugenol, which gives the leaves their clove-like aroma, methyl chavicol, linalool, and menthol (Hussain et al., 2017; Khan et al., 2010). Eugenol is important due to its demonstrated antimicrobial activity attributed to the hydroxyl group (oxygen linked to hydrogen) and antioxidant activity, among others (Dorman & Deans, 2000; Flegkas et al., 2019). The observation that mature leaves contain less eugenol compared to young leaves is probably attributed to the accumulation of oxidation reactions utilising eugenol when maturity is attained (Flegkas et al., 2019; D. Singh & Chaudhuri, 2018). On the other hand, methyl chavicol has been associated with antifungal activity specifically (Piras et al., 2018). Flavonoids of particular interest are orientin and vicenin which have shown activity against cancer cells and protection against radiation (Singh and Chaudhuri 2018). The fixed oils from seeds (18-22%) and leaves are both mainly composed of omega-3 fatty acids linoleic and α-linolenic acid. The seeds also contain polysaccharides (many sugars) and β-sitosterol (a cholesterol-like compound) whilst calcium, iron, copper, and zinc minerals, vitamin C and A have also been characterised from the plant (Pattanayak et al., 2010; D. Singh & Chaudhuri, 2018). Surprisingly, Holy basil is sometimes listed as a source of vitamin B in some food supplements, although it has been shown to only contain trace amount of vitamins B.
Evidence (Clinical & Preclinical)
Can Holy basil help against “brain fog”?
The concept of adaptogens continue to gain popularity in the Western world as remedies to help the human body adapt to stress and maintain its balance. Stress can be induced by numerous factors, including, but not limited to, psychological changes. Holy basil has been traditionally used as an adaptogen for a long time; however, is there evidence from high quality studies to support this use?
Two human trials demonstrated improvements of cognitive function in participants treated with Holy basil compared to placebo (Sampath et al., 2015; Saxena et al., 2012). In the first study, 40 healthy participants were given an ethanolic preparation of Holy basil leaves (300mg 3 times daily, cited as O. sanctum) and in the other study, 150 stressed participants were given a commercial preparation of Holy basil whole plant (400mg 3 times daily, cited as O. tenuiflorum). The results showed an improved working memory in the healthy participants after only 5 days on Holy basil and a significant reduction of stress-related symptoms such as fatigue, sleep, and sexual problems in stressed participants after 6 weeks of treatment.
In preclinical studies of Holy basil in stressed animals, two anti-stress compounds (ocimumoside A&B) were identified, which function to normalise physiological factors related to stress, suggesting its application as an adaptogen may be justified (D. Singh & Chaudhuri, 2018). Furthermore, Holy basil’s potential against cognitive psychological stress factors may follow from the fact that the compound eugenol has demonstrated inhibitory activity against the enzyme acetylcholinesterase involved in pathways contributing to Alzheimer’s disease (Giridharan et al., 2015). However, it remains more importantly to understand the mechanisms by which the compounds work, likely in synergy, and how Holy basil compares to other treatments.
Can Holy basil help against inflammation and pain?
Inflammation is a defence mechanism in response to a tissue injury to heal the affected tissue whilst pain is considered a physiological and psychological experience in response to a stimulus with or without inflammation. Herbal remedies are generally recommended in the management of non-acute pain, not associated with serious medical conditions, and of minor self-limiting nature. Clinical evidence in this disease state is constrained by limited high-quality studies and therefore the basis of the anti-inflammatory and analgesic applications is more reliant on the established traditional history and preclinical results.
Indeed, early preclinical studies have shown that both essential and fixed oils from Holy basil (cited as O. sanctum) significantly reduced inflammation in mice with induced paw swelling (Mahajan et al., 2013; S. Singh & Majumdar, 1997). Additional preclinical study of a topical gel prepared from Holy basil leaves (cited as O. sanctum) administered to rats with arthritis have shown a reduction in proteins and enzymes that regulates inflammation and pain including interleukin, tumour necrosis factor, similar to the effect of Atrogel (Arnica montana gel), by significantly constraining (50%) cyclooxygenase-1&-2 enzymes, which indirectly promote inflammation and pain (Ahmad et al., 2018). Different compounds have been identified that exert anti-inflammatory and analgesic activity, including the omega-3 fatty acid linolenic acid, which is also found in linseed oil, or phenolic compounds characterised from biological assays with specific action against cyclooxygenase-1&-2 enzymes, comparable to ibuprofen, naproxen and aspirin (Kelm et al., 2000).
In clinical investigations, a study of 22 healthy participants treated with ethanolic preparations of Holy basil leaves (300mg daily for 4 weeks, cited as O. sanctum) compared to placebo demonstrated an increase in anti-inflammatory response factors such as interleukin 4 cytokines, which are involved in wound healing (Mondal et al., 2011). Another study of 108 participants comparing the effects of 4% ethanolic solution of Holy basil (cited as O. sanctum) to 0.12% chlorhexidine mouthwash and placebo on dental plaque and gingival inflammation, found the two treatments to be equivalent (and superior to placebo) at reducing gingival bleeding and plaque when administered as 10mL solution twice daily for 30 days (Gupta et al., 2014). Furthermore, the authors concluded Holy basil to be a better treatment option since side effects associated with chlorhexidine, namely alteration in taste sensation and staining of teeth, were not reported. The overall limited evidence may explain the fact that anti-inflammatory and analgesic food supplements containing Holy basil often also contain other plants, including ginger (Zingiber officinale), or turmeric (Curcuma longa) for synergistic effect.
What are some implications of the evidence or lack thereof?
Chronic and/or unresolved inflammations are suggested to be underlying factors contributing to other diseases, including cancer and autoimmune disorders, and although insight into the link is still evolving, it possibly involves stress caused by the accumulation of oxidation reactions. This concept raises the questions; can Holy basil help against cancer? Or can it regulate the immune system?
Preclinical studies of Holy basil against human oral squamous (Manosroi et al., 2006), pancreatic (Shimizu et al., 2013), breast (D. Singh et al., 2014), and prostate cancer cell cultures (Dhandayuthapani et al., 2015), as well as studies in mice with metastatic lung tumour (Baliga et al., 2013) showed cytotoxic and antitumor activity by the inhibition of cancer cell proliferation, reduction of metastatic nodules, or induction of cancer cell programmed death. These and other investigations, although not overly impressive and sometimes contradicting, may offer potential for Holy basil to be utilised as intervention to slow the development of cancer. Although eugenol may be involved in inhibiting tumour formation, newly identified compounds belonging to the class of terpenes have shown potential as cytotoxic agents (Baliga et al., 2013; D. Singh et al., 2014).
Modulation of the immune system is either aimed at stimulating or suppressing immune response factors, depending on the desired effect. Trials conducted on healthy adults have shown that Holy basil can act as an immunostimulant, however results on sick patients are not as conclusive. The trial with healthy patients taking an ethanolic preparation of Holy basil leaves (300mg daily for 4 weeks, cited as O. sanctum) compared to placebo showed stimulation of the immune response factors T-helper, Natural Killer cells and interferon-γ production with no significant side effects (Mondal et al., 2011). On the other hand, a cross over study on mild to moderate asthmatic patients taking Holy basil fresh leaves drug (200mg twice daily for 7 days, cites as O. sanctum) showed some anti-asthmatic properties by improvement of FEV1 and PEFR values, although to a much lesser extent than the standard treatment Salbutamol (2mg twice daily for 7 days) (Vinaya et al., 2017). Immunomodulatory activity is attributed to omega-3 fatty acids compounds in the fixed oil namely linoleic and α-linolenic acids which inhibit histamine action and limit the production of arachidonate, an omega-6 fatty acid that binds cyclooxygenase-1&-2 enzymes (D. Singh & Chaudhuri, 2018).
Toxicology & Safety
Due to its long-standing history of medical and religious applications, Holy basil is attested to be safe. In the trials conducted in humans there is seldom any report of untoward associated effects. Furthermore, in vivo animal toxicity studies presented below support its safety.
Investigations on the effect of acute but non-toxic doses of Holy basil in rodents demonstrated that a methanolic preparation of the whole plant (1g/kg daily orally for 28 days, cited as O. sanctum) did not induce toxicity to organs including liver, kidney, and heart, or to the motor and sensory systems (Raina et al., 2015). These results validated previous conclusions that ethanolic preparations of the leaves administered orally to rodents at even higher doses (2g/kg for 28 days and 5g/kg for 14 days, cited as O. sanctum) were nonfatal, nontoxic to the nervous system, and showed no sign of untoward effects (Chandrasekaran et al., 2013; Gautam & Goel, 2014). On the other hand, it was observed that at the highest dose Holy basil could protect DNA against damage (Chandrasekaran et al., 2013) and similarly protect against liver damage (Bedi et al., 2016; Lahon & Das, 2011) thus furthering research into its inhibition of genetic toxicity induced by heavy metals such as arsenic and mercury. Although recognised as safe, it must be noted that Holy basil impairment of fertility (Poli & Challa, 2019), albeit reversible, necessitates the cautioned use of the plant.
The is some evidence to support the use of Holy basil as a memory booster and against inflammation and pain, although the evidence is limited primarily due to low quality trials often in comparison with placebo with few comparing against other treatments. The same more could be said about its use against infections or to manage metabolic disorders which were not discussed here. In an effort to validate traditional uses, it seems logical to investigate similar traditional preparations however great insight might be gained from exploring different methods and solvents as evidenced by the identification of terpene compounds with low solubility in water and alcohol and which are associated with cytotoxic and metabolic activities (Patil et al., 2011; D. Singh et al., 2014). The compound eugenol is noticeably associated with various beneficial effects of Holy basil, since it is known to have biological effects as an antioxidant and radical scavenger which is of relevance in many illnesses.
It remains that an important consideration with Holy basil is the taxonomy such that O. tenuiflorum Rama, Krishna and O. gratissimum could be used interchangeably to designate the same plant. Whilst genetic validation tools have proven helpful in assigning a plant variant to a correct taxon, in the case of Holy basil the outdated name O. sanctum does not seem to be universally retracted, possibly as it evokes a religious significance, which is cause for confusion. This conflict particularly in product labelling, can be problematic for consumers’ information and safety. The quality standards set by the British Pharmacopoeia for Holy basil products to be marketed in the UK require the established presence of the compounds rosmarinic acid, eugenol, methyl eugenol, and ursolic acid and as mentioned eugenol is not found in O. gratissimum.
*Ayurveda is an Indian medical system recognised as one of the most ancient forms of medicine. It adopts a holistic and subjective approach to health considering normality on an individual basis, defining unique imbalances and thus suggesting tailored treatment. All matter is considered to have intrinsic qualities or characteristics like taste depending on its effects on the body.
Disclaimer: In this essay we do not to advise or recommend herbs for medicinal or health use. This information is intended for educational purposes only and should not be considered as a recommendation or an endorsement of any particular medical or health treatment. The use of any such product should be based on the appropriate advice of a health care professional or based on the information available in the patient information leaflets (i.e. for THR products).
© Luta Kora Mbaka 2020. All Rights Reserved.
About the author
I was born and raised in The Congo and moved to Toronto, Canada to pursue higher education. I have always known I wanted to be a scientist. I am currently completing a Master of Science degree at University College London in Medicinal Natural Products and Phytochemistry.
Bijay chaurasia – Own work, CC BY-SA 4.0, Public Domain, https://commons.wikimedia.org/w/index.php?curid=42253023 /Retrieved 01 June 2020
Francisco Manuel Blanco (O.S.A.) – Flora de Filipinas […] Gran edicion […] [Atlas II]., Public Domain, https://commons.wikimedia.org/w/index.php?curid=5056621 / Retrieved 01 June 2020
Holy basil Image. Encyclopædia Britannica
https://www.britannica.com/plant/holy-basil#/media/1/2050300/241175 /Retrieved 01 June 2020
National Center for Biotechnology Information. PubChem Database. https://pubchem.ncbi.nlm.nih.gov /Retrieved 02 June 2020
POWO (2019). “Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://www.plantsoftheworldonline.org/ Retrieved 01 June 2020.”
Tulsi devotion image. Encyclopædia Britannica
https://www.britannica.com/plant/holy-basil#/media/1/2050300/241230 /Retrieved 01 June 2020
Vaikoovery – Own work, CC BY 3.0, Public Domain, https://commons.wikimedia.org/w/index.php?curid=15964545 /Retrieved 01 June 2020
Ahmad, A., Abuzinadah, M. F., Alkreathy, H. M., Banaganapalli, B., & Mujeeb, M. (2018). Ursolic acid rich Ocimum sanctum L leaf extract loaded nanostructured lipid carriers ameliorate adjuvant induced arthritis in rats by inhibition of COX-1, COX-2, TNF-α and IL-1: Pharmacological and docking studies. PLoS ONE, 13(3). https://doi.org/10.1371/journal.pone.0193451
Baliga, M. S., Jimmy, R., Thilakchand, K. R., Sunitha, V., Bhat, N. R., Saldanha, E., Rao, S., Rao, P., Arora, R., & Palatty, P. L. (2013). Ocimum Sanctum L (Holy Basil or Tulsi) and Its Phytochemicals in the Prevention and Treatment of Cancer. Nutrition and Cancer, 65(sup1), 26–35. https://doi.org/10.1080/01635581.2013.785010
Bedi, O., Reddy Bijjem, K. v, Kumar, P., & Gauttam, V. (2016). Herbal Induced Hepatoprotection and Hepatotoxicity: A Critical Review. Indian Journal of Physiology and Pharmacology, 60(1), 6–21.
Chandrasekaran, C. V., Srikanth, H. S., Anand, M. S., Allan, J. J., Viji, M. M. H., & Amit, A. (2013). Evaluation of the mutagenic potential and acute oral toxicity of standardized extract of Ocimum sanctum (OciBestTM). Human & Experimental Toxicology, 32(9), 992–1004. https://doi.org/10.1177/0960327112472992
Cohen, M. M. (2014). Tulsi – Ocimum sanctum: A herb for all reasons. Journal of Ayurveda and Integrative Medicine, 5(4), 251–259. https://doi.org/10.4103/0975-9476.146554
Das, S. K., & Vasudevan, D. M. (2006). Tulsi: The Indian holy power plant. Natural Product Radiance, 5(4), 279–283.
Dhandayuthapani, S., Azad, H., & Rathinavelu, A. (2015). Apoptosis Induction by Ocimum sanctum Extract in LNCaP Prostate Cancer Cells. Journal of Medicinal Food, 18(7), 776–785. https://doi.org/10.1089/jmf.2014.0008
Dorman, H. J. D., & Deans, S. G. (2000). Antimicrobial agents from plants: antibacterial activity of plant volatile oils. Journal of Applied Microbiology, 88(2), 308–316. https://doi.org/10.1046/j.1365-2672.2000.00969.x
Edwards, S. E., da Costa Rocha, I., Williamson, E. M., & Heinrich, M. (2015). Holy Basil (Ocimum tennuiflorum L). In S. E. Edwards, I. da Costa Rocha, E. M. Williamson, & M. Heinrich (Eds.), Phytopharmacy: An Evidence-Based Guide to Herbal Medicinal Products (2nd ed., pp. 189–201).
Flegkas, A., Milosević Ifantis, T., Barda, C., Samara, P., Tsitsilonis, O., & Skaltsa, H. (2019). Antiproliferative Activity of (-)-Rabdosiin Isolated from Ocimum sanctum L. Medicines, 6(1), 37. https://doi.org/10.3390/medicines6010037
Gautam, M., & Goel, R. (2014). Toxicological Study of Ocimum sanctum Linn Leaves: Hematological, Biochemical, and Histopathological Studies. Journal of Toxicology. https://doi.org/10.1155/2014/135654
Giridharan, V. v., Thandavarayan, R. A., & Konishi, T. (2015). Ocimum sanctum Linn. (Holy Basil) to Improve Cognition. In Diet and Nutrition in Dementia and Cognitive Decline (pp. 1049–1058). Elsevier Inc. https://doi.org/10.1016/B978-0-12-407824-6.00098-7
Gupta, D., Bhaskar, D. J., Gupta, R. K., Karim, B., Jain, A., Singh, R., & Karim, W. (2014). A randomized controlled clinical trial of Ocimum sanctum and chlorhexidine mouthwash on dental plaque and gingival inflammation. Journal of Ayurveda and Integrative Medicine, 5(2), 109–116. https://doi.org/10.4103/0975-9476.131727
Hussain, A. I., Chatha, S. A. S., Kamal, G. M., Ali, M. A., Hanif, M. A., & Lazhari, M. I. (2017). Chemical composition and biological activities of essential oil and extracts from Ocimum sanctum. International Journal of Food Properties, 20(7), 1569–1581. https://doi.org/10.1080/10942912.2016.1214145
Jamshidi, N., & Cohen, M. M. (2017). The Clinical Efficacy and Safety of Tulsi in Humans: A Systematic Review of the Literature. Evidence Based Complementary and Alternative Medicine. https://doi.org/10.1155/2017/9217567
Jürges, G., Sahi, V., Rodriguez, D. R., Reich, E., Bhamra, S., Howard, C., Slater, A., & Nick, P. (2018). Product authenticity versus globalisation—The Tulsi case. PLoS ONE, 13(11). https://doi.org/10.1371/journal.pone.0207763
Kelm, M. A., Nair, M. G., Strasburg, G. M., & DeWitt, D. L. (2000). Antioxidant and cyclooxygenase inhibitory phenolic compounds from Ocimum sanctum Linn. Phytomedicine, 7(1), 7–13. https://doi.org/10.1016/S0944-7113(00)80015-X
Khan, A., Ahmad, A., Akhtar, F., Yousuf, S., Xess, I., Khan, L. A., & Manzoor, N. (2010). Ocimum sanctum essential oil and its active principles exert their antifungal activity by disrupting ergosterol biosynthesis and membrane integrity. Research in Microbiology, 161(10), 816–823. https://doi.org/10.1016/j.resmic.2010.09.008
Kulkarni, K., & Adavirao, B. (2018). A review on: Indian traditional shrub Tulsi (Ocimum sanctum): The unique medicinal plant. Journal of Medicinal Plants Studies, 6(2), 106–110.
Lahon, K., & Das, S. (2011). Hepatoprotective activity of Ocimum sanctum alcoholic leaf extract against paracetamol-induced liver damage in Albino rats. Pharmacognosy Research, 3(1), 13–18. https://doi.org/10.4103/0974-8490.79110
Mahajan, N., Rawal, S., Verma, M., Poddar, M., & Alok, S. (2013). A phytopharmacological overview on Ocimum species with special emphasis on Ocimum sanctum. Biomedicine and Preventive Nutrition, 3(2), 185–192. https://doi.org/10.1016/j.bionut.2012.08.002
Manosroi, J., Dhumtanom, P., & Manosroi, A. (2006). Anti-proliferative activity of essential oil extracted from Thai medicinal plants on KB and P388 cell lines. Cancer Letters, 235(1), 114–120. https://doi.org/10.1016/j.canlet.2005.04.021
Mondal, S., Varma, S., Bamola, V. D., Naik, S. N., Mirdha, B. R., Padhi, M. M., Mehta, N., & Mahapatra, S. C. (2011). Double-blinded randomized controlled trial for immunomodulatory effects of Tulsi (Ocimum sanctum Linn.) leaf extract on healthy volunteers. Journal of Ethnopharmacology, 136(3), 452–456. https://doi.org/10.1016/j.jep.2011.05.012
Patil, R., Patil, R., Ahirwar, B., & Ahirwar, D. (2011). Isolation and characterization of anti-diabetic component (bioactivity-guided fractionation) from Ocimum sanctum L. (Lamiaceae) aerial part. Asian Pacific Journal of Tropical Medicine, 4(4), 278–282. https://doi.org/10.1016/S1995-7645(11)60086-2
Pattanayak, P., Behera, P., Das, D., & Panda, S. (2010). Ocimum sanctum Linn. A reservoir plant for therapeutic applications: An overview. Pharmacognosy Review, 4(7), 95–105. https://doi.org/10.4103/0973-7847.65323
Petruzzello, M. (2019). Holy basil | Description, Uses, & Facts | Britannica. Encyclopædia Britannica, Inc. https://www.britannica.com/plant/holy-basil
Piras, A., Gonçalves, M. J., Alves, J., Falconieri, D., Porcedda, S., Maxia, A., & Salgueiro, L. (2018). Ocimum tenuiflorum L. and Ocimum basilicum L., two spices of Lamiaceae family with bioactive essential oils. Industrial Crops and Products, 113, 89–97. https://doi.org/10.1016/j.indcrop.2018.01.024
Poli, V., & Challa, C. (2019). A comparative study of eugenol and Ocimum sanctum Linn. leaf extract on the antifertility effect in female albino rats. Journal of the Chinese Medical Association, 82(3), 231–234. https://doi.org/10.1097/JCMA.0000000000000034
Raina, P., Chandrasekaran, C. v., Deepak, M., Agarwal, A., & Ruchika, K. G. (2015). Evaluation of subacute toxicity of methanolic/aqueous preparation of aerial parts of O. sanctum in Wistar rats: Clinical, haematological, biochemical and histopathological studies. Journal of Ethnopharmacology, 175, 509–517. https://doi.org/10.1016/j.jep.2015.10.015
Sampath, S., Mahapatra, S. C., Padhi, M. M., Sharma, R., & Talwar, A. (2015). Holy Basil (Ocimum Sanctum Linn.) Leaf Extract Enhances Specific Cognitive Parameters in Healthy Adult Volunteers: A Placebo Controlled Study. Indian Journal of Physiology and Pharmacology, 50(1), 69–77.
Saxena, R., Singh, R., Kumar, P., Singh Negi, M., Saxena, V., Geetharani, P., Allan, J., & Venkateshwarlu, K. (2012). Efficacy of an Extract of Ocimum tenuiflorum (OciBest) in the Management of General Stress: A Double-Blind, Placebo-Controlled Study. Evidence Based Complementary and Alternative Medicine. https://doi.org/10.1155/2012/894509
Shimizu, T., Torres, M. P., Chakraborty, S., Souchek, J. J., Rachagani, S., Kaur, S., Macha, M., Ganti, A. K., Hauke, R. J., & Batra, S. K. (2013). Holy Basil leaf extract decreases tumorigenicity and metastasis of aggressive human pancreatic cancer cells in vitro and in vivo: Potential role in therapy. Cancer Letters, 336(2), 270–280. https://doi.org/10.1016/j.canlet.2013.03.017
Sim, L. Y., Rani, N. Z. A., & Husain, K. (2019). Lamiaceae: An insight on their anti-allergic potential and its mechanisms of action. Frontiers in Pharmacology, 10. https://doi.org/10.3389/fphar.2019.00677
Singh, D., & Chaudhuri, P. K. (2018). A review on phytochemical and pharmacological properties of Holy basil (Ocimum sanctum L.). Industrial Crops and Products, 118, 367–382. https://doi.org/10.1016/j.indcrop.2018.03.048
Singh, D., Chaudhuri, P. K., & Darokar, M. P. (2014). New Antiproliferative Tricyclic Sesquiterpenoid from the Leaves of Ocimum sanctum. Helvetica Chimica Acta, 97(5), 708–711. https://doi.org/10.1002/hlca.201300269
Singh, S., & Majumdar, D. K. (1997). Evaluation of anti-inflammatory activity of fatty acids of Ocimum sanctum fixed oil. Indian Journal of Experimental Biology, 35(4), 380–383.
Uritu, C., Mihai, C., Stanciu, G., Dodi, G., Alexa-Stratulat, T., Luca, A., Leon-Constantin, M., Stefanescu, R., Bild, V., Melnic, S., & Tamba, B. (2018). Medicinal Plants of the Family Lamiaceae in Pain Therapy: A Review. Pain Research and Management. https://doi.org/10.1155/2018/7801543
Verma, S. (2016). Chemical constituents and pharmacological action of Ocimum sanctum (Indian holy basil-Tulsi). The Journal of Phytopharmacology, 205–207.
Vinaya, M., Kudagi, B. L., Mohammed, A. K., & Mallikarjuna, S. (2017). Bronchodilator activity of Ocimum sanctum Linn. (tulsi) in mild and moderate asthmatic patients in comparison with salbutamol: a single-blind cross-over study. International Journal of Basic & Clinical Pharmacology, 3. https://doi.org/10.18203/2319-2003.ijbcp20170543
WHO. (2002). WHO Monographs on Selected Medicinal Plants. In WHO (Vol. 2, pp. 206–216). WHO, Geneva.