Abstract
Objectives
This systematic review aimed to evaluate the chemical compositions and Pharmacological applications of Ocimum basilicum, known as sweet basil, and Ocimum americanum, known as hoary basil, to assess their antimicrobial properties. Both plants are renowned for their culinary uses and medicinal properties, with studies suggesting potential therapeutic benefits due to their rich essential oil.
Methods
A systematic approach was adopted to gather and analyze the relevant literature on the chemical profiles and pharmacological activities of Ocimum basilicum and Ocimum americanum. Electronic databases including Web of Science, ScienceDirect, Google Scholar, and PubMed were searched using keywords such as chemical composition of Ocimum basilicum, chemical composition of Ocimum americanum, antimicrobial activities of Ocimum basilicum, and antimicrobial activities of Ocimum americanum.
Results
Ninety-nine articles meeting the determined inclusion criteria were incorporated in this systematic review. Several studies have consistently demonstrated the antimicrobial activities of these 2 plants, although the specific compounds responsible for this activity vary between the 2 species.
Conclusion
The diverse array of bioactive molecules present in these plants contributes to their pharmacological effects, suggesting avenues for further research into their therapeutic applications. This review supports the continued exploration of the medicinal properties and potential development of sweet basil and hoary basil as antimicrobial agents.
Introduction
Traditional medicinal plants are an important resource of drugs that are useful in treating a variety of ailments. Natural products involve the use of types of plant components, such as bark, flower, fruit, leave, resin, rhizome, root, seed, and stem.1-3 The cornerstone of international efforts to fight diseases and treat illnesses has been the utilization of medicinal plants. 4 One of the most promising substitutes for synthetic medications in veterinary medicine, like antibiotics used as encouraging agents, is plant-based products, which can be utilized to treat animals, especially humans.5,6
Comparing medicinal plants to their synthetic counterparts, medicinal plants are less harmful. 7 Antimicrobial resistance is reportedly the largest threat to successfully treating infections brought on by dangerous microorganisms worldwide at the moment. Antimicrobial agent resistance has been shown to have negative effects on clinical and therapeutic outcomes. This has been linked to higher medical care, levels of disease and death, and medical expenses, as well as fails in therapy and the need for higher-priced and secure substitute medical products. New antimicrobial medicines are desperately needed in the ongoing battle against microbial diseases.8-10 Essential oils extracted from aromatic and therapeutic plants have been shown to have antibacterial, antifungal, anticancer, antidiarrheal, analgesic, and antioxidant qualities. 11
The word Ocimum, which belongs to the Lamiaceae family, is derived from a Greek verb meaning aromatic. Ocimum, which has over 150 species, is known as the king of herbs owing to its many uses in pharmacology, traditional medicine, and the cosmetics sector.12,13 Furthermore, Africa is the primary diversified place where the plants in the genus Ocimum are used as edible herbs. These plants are naturally grown in some parts of America, Africa, and Asia. 14 Essential oils, which are present in practically every part of the Ocimum, including the leaf and flower, make up the majority of the composition of Ocimum species bioactive molecules.15,16 Ocimum species have historically been used to control the COVID-19 epidemic, particularly in developing nations.17,18
Ocimum americanum, commonly known as hoary basil, and Ocimum basilicum, also known as sweet basil leaves, are 2 plant species that belong to the Ocimum species and are utilized extensively for their many medicinal uses. Numerous chemicals found in these plants, including tannins, carotenoids, flavonoids, and estragole, have anti-inflammatory, antioxidant, antiviral, hypoglycemic, hypolipidemic, antibacterial, anticancer, and wound-healing properties.19-21 Although Ocimum basilicum and Ocimum americanum both have antibacterial properties, the specific compounds responsible for these actions may differ between the 2 species. However, to the best of our knowledge, there is no literature review was reported in the comparison of chemical structure and pharmacological properties of these 2 Ocimum species. Therefore
Ocimum basilicum and Ocimum americanum photography.
Materials and Methods
Search Strategy
All articles published for 8 years up to 2023, that had descriptors were included in the search approach. Key scientific resources like ScienceDirect, Web of Science, PubMed, and Google Scholar were consulted in order to find surveys. The terms “chemical composition of Ocimum basilicum,” “chemical composition of Ocimum americanum,” “antimicrobial activities of Ocimum basilicum,” and “antimicrobial activities of Ocimum americanum” were among the particular keywords we employed.
Study Selection
The authors performed a calibration exercise before starting the review to ensure consistency across the reviewers. Article's title, references, year of publication, country, journal title, techniques, and main conclusions were all taken out of the document extracted from scientific databases. Some data obtained after database has been hunted are mentioned in Table 1. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis standards, the following eligibility criteria for literature selection were used: studies involving the essential chemical composition of Ocimum basilicum and Ocimum americanum with recognized antimicrobial activity. After duplicate articles were eliminated, the titles of each remaining article were examined. The method of inclusion and exclusion determination involved 2 steps, with the first phase entailing the selection of the abstract and the topic of the document. Figure 2 shows a schematic diagram of the study selection process used for the systematic review. Discussion was utilized among the contributing authors to resolve any discrepancies regarding data extraction or article selection. Our inclusion criteria are outlined as follows: (a) articles published in English, (b) original research manuscripts, ( c) review articles, (d) book chapters, (e) recent articles published within the last 8 years, with the exclusion of certain articles obtained from Google Scholar due to their significance.
Schematic diagram of study selection for the systematic review.
Studies on Chemical Profile and Pharmacological Application of Ocimum basilicum and Ocimum americanum in the Literature.
Study Identification and Selection
Out of the 153 published articles that were included in the thorough examination, 99 of them satisfied our inclusion and exclusion criteria. The relevance of these chosen publications to the chemical profile and pharmacological evaluation of Ocimum basilicum and Ocimum americanum was then determined.
Researchers from Mauritius document traditional herbal remedies used globally to treat hypertension by conducting a systematic assessment of global ethnobotanical field investigations. Their main idea was to conduct a thorough review of global ethnobotanical field research on traditional herbal remedies for hypertension. 22 Scientific papers published on the Holy-basil and Essential Oils (EOs) from Africa that have several distinct morphological features and are used in ethnobotanical medicine to cure human ailments as key findings based on the ethnobotany, phytochemistry, and toxicity of bioactive molecules from African and Holy-basil: Current developments and future opportunities for antibacterial and antiparasitic pharmacology. 23
Momordica charantia and Ocimum basilicum leaves cold maceration extraction by water for 72 h were used to protect rats against induced pancreatic cancer as it was approved by researchers in the analysis of the Kras gene in rats with pancreatic cancer that were given extracts from the leaves of Momordica charantia and Ocimum basilicum. 24 The impact of varying solvents and the number of extraction stages on the polyphenol concentration and antioxidant potential of extracts made from basil leaves (Ocimum basilicum L.) showed the concentration of phenolic compounds and the antioxidant activity of the extracts have a favorable association. 25
The impact of soil types on the chemical composition of purple basil essential oil, as determined by Clevenger apparatus essential oil extraction, demonstrated the influence of soil types on the chemical composition of Ocimum basilicum and Ocimum americanum. As a result, scientists and cultivators maximize the production of essential oils from purple basil by using the right type of soil. 26 An update on the use of natural ingredients in diabetic mellitus treatment: a comprehensive analysis demonstrated on numerous herbs indicated antidiabetic effects via controlling glucose abruption, insulin sensitivity to cells, insulin secretion, etc Combining the proteins from grains and basil seeds increases the biological value of the proteins by supplementing the limited amino acids in a reciprocal manner as it was done on Ocimum basilicum Linn. basil seeds protein isolate: physicochemical and functional analysis.27,28 Some of the selected articles were screened and included after their inclusion criteria indicated by the following Table 1.
General Information and Chemical Structure of Ocimum basilicum
Ocimum basilicum commonly named sweet basil herb is one of the species kind of the genus Ocimum that is native to South America, Africa, and Asia.54,55 Ocimum basilicum can grow in a variety of environments and climates. It prefers warm temperatures and can thrive in cool, humid climates as well as tropical regions with temperatures ranging from 6 to 24°C. 56
Ocimum basilicum plant belongs to the Ocimum species that is sold commercially.57,58 According to the scholar Bagomo et al 57 and Dharsono et al, 44 there are 6 distinct morphologies of this plant: sweet basil with green leaves, small-leaf basil (green cultivation with short, constricted leaf that develops round), lettuce-leaf basil with broad leaf, sweet basil A (green leaf with purple flower and stem), sweet basil B (purple leaves, flower, and stem), and sweet basil C (wide listered leaves that look like sweet basil B). Ocimum basilicum has large green leaves, glabrous, woody stems, and a broadly elliptical shape that is 2.5 to 5 cm by 1 to 2.5 cm. It is 20 to 80 cm tall (Figure 1). 59
The fruit of Ocimum basilicum has traditionally been used as herbal remedy for eye diseases, diarrhea, inflammation, and worm infestation. 60 Ocimum basilicum leaves and blossoms have historically been advantageous as a stimulant and an anthelmintic medicine. They can also be fermented as tea to get rid of diarrhea, queasiness, and gas. Essential oils from Ocimum basilicum are frequently used to treat wasp stings, snakebites, colds, and seizures. 61 In China, the polysaccharide component of Ocimum basilicum has long been used to treat cancer.44,62 Ocimum basilicum is used in Mediterranean cuisines, including Greek and Italian cuisines, in South Europe. 63 This traditional medicinal plant called Ocimum basilicum is used to treat cardiovascular diseases in traditional Chinese medicine. In one study, rats’ blood pressure levels were dose-dependently lowered by the aqueous extract from 100 to 400 mg. It also had the capacity to scavenge reactive oxygen species and produce a vasorelaxant effect. 64
The primary nutrients found in Ocimum basilicum include mineral contents like calcium and phosphorus, as well as vitamins such as retinol which is used to assist the immune system, your body's natural protection against disease and infection, in doing its function, improving eyesight in low light. maintaining the health of the epidermis and the lining of specific bodily parts, like the nose, ascorbic acid that is commonly known as vitamin C, and β-carotene.65,66 Alkaloid, flavonoid, phenol, saponins, tannin, terpenoid, carbohydrate sugars, cardiac glycoside, cholesterols, glycoside, and phlorotannins are among the phytochemical components found in Ocimum basilicum.67,68 As a result, it may possess qualities that are immunomodulatory, analgesic, cardioprotective, anti-inflammatory, antimicrobial, antiviral, anticancer, antifungal, antidiabetic, and allergic.69-71 According to Prinsi et al 72 and Da Silva et al,46,73 flavonoids and phenolic substances extracted from Ocimum basilicum have antioxidant activity (Table 2).
Selected bioactive compounds identified from Ocimum basilicum.
The biosynthesis of phenylpropanoid compounds is produced from the shikimate pathway and regulated by several groups of enzymatic reactions through metabolic channels. All phenylpropanoids are derived from cinnamic acid, which is formed from phenylalanine by the deamination action of phenylalanine ammonia-lyase. As indicated in the figure below (Figure 3), because of the economic importance of essential oil production, basil is considered as a target for bioengineering. Researcher studies on cold stress changes antioxidant defense system, phenylpropanoid contents, and expression of genes involved in their biosynthesis in Ocimum basilicum and methyl chavicol and eugenol biosynthesis pathway in basil glandular trichomes.29,74
Enzyme abbreviations relate to the biosynthesis pathway of methyleugenol and methylchavicol in basil glandular trichomes: phenylalanine ammonia-lyase (PAL); p-coumarate/cinnamate carboxyl methyltransferase (CCMT); cinnamate 4-hydroxylase (C4H); 4-coumarate:CoA ligase ((4CL); p-coumarate 3-hydroxylase (C3H); p-coumaroyl shikimate transferase (CST); p-coumaroyl 5-O-shikimate 30-hydroxylase (CS30H); caffeoyl-CoA O-methyltransferase (CCOMT); cinnamoyl-CoA reductase (CCR); eugenol (and chavicol) synthase (EGS); eugenol O-methyltransferase (EOMT); chavicol O-methyltransferase (CVOMT). 75
General Information and Structural Profile of Ocimum americanum
Ocimum americanum is a species of annual herb in the Lamiaceae family. It is often referred to as hoary basil, lime basil, or American basil. It is grown naturally in the Australian State, Australian external territory, and some regions of Mexican evergreen forests and is native to Africa, the Indian Subcontinent, China, and South-east Asia. 36 The plant can reach a height of 40 cm and has a lengthy taproot that reaches far into the ground. It features tiny, clustered white or purple blooms and opposite, serrated leaves. The entire plant has a strong citrus-like scent and is quite aromatic. Consequently, it shares culinary applications with sweet basil (Figure 1).
As reported in previous studies Ocimum americanum is one of the well-known species from the genus Ocimum, which has historically been used to treat a variety of illnesses in societies, including bronchitis, colds, coughs, and cataracts. 76 Its leaves are used to flavor soups and to treat migraines, diarrhea, and toothaches. 77 Its leaves can also be used to make a decoction that is used to cure malaria, fever, and nose bleeding; its blended leaves are used to treat skin problems caused by parasites. Leaf infusion is also used to cure fever, indigestion, and diarrhea as well as drinks are prepared from seeds, while eye disorders are treated with leaf juice.78,79
Primary metabolites such as protein, amino acid, carbohydrate, fatty acid, and minerals are among the nutritional elements found in Ocimum americanum plants that are good for human health.80,81 According to Mustafa and El-kamali 82 calcium content, iron content, salt content, potassium content, manganese content, and zinc content were detected in significant amounts in the elemental analysis of Ocimum americanum plant leaf and flower conducted using atomic absorption spectroscopy and flame emission techniques (Table 3).
Selected bioactive compounds identified from Ocimum americanum.
Pharmacological Application of Ocimum basilicum and Ocimum americanum
El-Shenawy et al 83 reported that essential oils showed greater sensitivity in treating Gram-positive bacteria. Variations in the composition of cell walls were the reason for this. Essential oils could not enter Gram-negative bacteria because of an outer capsule that kept them out of the cell.
The tablet is made up of a large intricate bacterial cell wall with an outer membrane covering a layer of peptidoglycan that is 2–3 nm thick. A distinction between the cell walls of Gram-positive and Gram-negative bacteria is the existence of an outer membrane. Braun lipoproteins are strongly covalently bonded to peptidoglycan and the outer membrane. This facilitates the water-repellent structure of the essential oil's penetration into Gram-positive bacteria's cell walls.84,85
Essential oils can be extracted from medicinal plants using various techniques, including solvent extraction, enfleurage, cohobation, steam distillation, hydrodistillation, and maceration.49,86 If this method is only to be used within the community, it will take some time to complete. Alternatively, because essential oils often contain compounds from the terpenoid and phenylpropanoid families, the Ocimum plant has been widely used traditionally to cure bacterial infections. Juice extracted from the Ocimum can be used to cure otitis and ease dental pain. Another use of this plant is as an infusion for mouthwash. This plant decoction has antibacterial and anesthetic properties. The leaves and stems can be decocted to cure fever, diarrhea, and inflammation of the nasal mucous membranes. 87
It has been demonstrated that Ocimum species has a wide variety of essential oil components, particularly those belonging to the monoterpenoid and sesquiterpenoid groups and certain phenylpropanoids. 88 Malapermal et al 89 revealed that an investigation was conducted into the antidiabetic effect of Ocimum americanum. Based on the agar dilution method and broth micro-dilution method, they worked with ethanol and aqueous solvent extracts of Ocimum americanum on a variety of microorganisms, including Salmonella species, Bacillus subtilis, Pseudomonas aeruginosa, and Staphylococcus aureus, which demonstrated better antidiabetic action. The medicinal value of basil was studied by researchers using hot water mixed basil leaves on animal rats. Serum creatinine, Blood Urea Nitrogen (BUN), and uric acid were measured in control, Thoracic Aortic Aneursym (TAA), and basil leaf extract-treated rats, as well as in rats exposed to basil leaf extract plus TAA and basil leaf extract. The results showed no significant differences in serum creatinine levels between the TAA and basil leaf extract-treated rats and the control rats. 90
Yibeltal and his coworkers 91 worked on n-hexane esterified essential oils were used to extract Ocimum basilicum, and the extracted essential oils demonstrated antimicrobial activity against all tested bacteria, including staphylococcus ATCC-25923, Escherichia coli 0157H7, and fungal species, including versicolor is, niger, and albicans in both the broth dilution method and the disc-diffusion assay. Zones of inhibition and Minimum Inhibitory Concentration (MIC) of the essential oil extracted by hydrodistillation recorded in the micro-dilution and disc-diffusion method was 8.00 ± 0.19 mm to 26.43 ± 2.19 mm and 3.12-100 µg/ml by Mahendran and Vimolmangkang16,92 on the bacterial species of Bacillus subtilis, Streptococcus pyogenes, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Salmonella paratyphi, Aeromonas hydrophila, Pseudomonas aeruginosa, and Enterobacter aerogenes.
Ocimum basilicum seed essential oils indicated a sort of MIC between 1.02 and 2.03 µg/ml for all studied bacterial straining of S. aureus, K. pneumoniae, P. mirabilis, E. coli, and P. aeruginosa. With a minimum inhibitory concentration (MIC) of 1.3 µg/ml, the essential oil curiously inhibited the growth of the fungus species candida albicans significantly more than the potential antifungal drug fluconazole. 8 According to Jasicka-Misiak et al, 93 anti-inflammatory and antidiabetic activity of the hydrodistilled residue of Ocimum americanum showed potential activities. A pharmacological analysis of Ocimum americanum revealed that alcohol and ethyl acetate have antibacterial properties and that extracts from the leaves and flowers inhibited the enzymes tyrosinase, butyrylcholine, and acetylcholine. The specific bacterial and fungal strains of Salmonella enterica, Candida albicans, C. tropicalis, Staphylococcus aureus, and Serovar typhimurium were all suppressed by the extracts. 77 Based on Ali et al, 94 crude extracts of Ocimum americanum demonstrated toxicity against artemia salina nauplii as it investigated biogenic zinc oxide nanoparticles synthesized using Ocimum americanum plant extract for antimicrobial and cytotoxicity effects of bacillus cereus, Klebsiella pneumonia, S. aureus, E. coli, S. aureus, and C. albicans. Reports by Dharsono and his coworkers 44 detail the antimicrobial activity of certain essential oils against Streptococcus species obtained from pigs, along with the minimum inhibitory concentration of an antibacterial test used to assess the oils’ inhibitory power. Strong activity is seen at MIC concentrations between 101 and 500 µg/ml, and moderate activity is found at MIC ranges between 500 and 1000 µg/ml. Dharsono et al. have gone on to test Ocimum basilicum against a number of bacteria, including mutants, S. aureus, B. cereus, L. monocytogenes, E. coli, P. aeruginosa, and S. typhi. The results showed MIC values below 100 µg/ml, indicating strong activity, both in Ocimum sanctum and others. Based on de Aguiar et al, 95 only 3 Ocimum species showed strong to weak activity, and Ocimum basilicum is the most commonly used and widely available.
A research done by Vidhya et al 96 to examine the antibacterial activities of Ocimum americanum leaf extracts in aqueous, acetone, methanol, and ethyl acetate against B. cereus, C. penfrigens, K. pneumoniae, and S. paratyphi. The ethyl acetate leaf extract of the Ocimum americanum plant demonstrated substantial antimicrobial properties in contrast to all confirmed pathogens, with B. cereus exhibiting the highest inhibition, while C. pentrigens indicated the least amount of inhibition in the aqueous extract. According to this article, the range of minimum inhibitory concentration values is 0.78 µg/ml to 50 µg/ml, while the range of minimum bacterial concentration or minimum fungal concentration is 1.56 µg/ml to 50 µg/ml current research on the antibacterial activity of an aqueous, acetonic, 70% of hydroethanolic extract and its chloroform, ethyl acetate was accompanied on the aerial sections of Ocimum americanum. The results demonstrated that the antibacterial activity of the acetonic and hydroethanolic extracts and their fractions was effective against B. cereus, S. aureus, and C. albicans.
The hydroethanolic extract's ethyl acetate fraction, at 250 mg/ml demonstrated the highest antibacterial activity against B. cereus, with an inhibition zone of 26.00 ± 0.00 and a minimum inhibitory concentration of 62.5 mg/ml. 94
According to Sadegh Kiani, 97 because of its highest richness in secondary metabolite bioactive medicinal plants, Ocimum basilicum, also known as great basil, is used in various areas of pharmaceutical activity, including antioxidants, antiosteoporotic, anxiolytic and tranquilizers, anti-Colitis, antibacterial, and cytotoxic effects; it is also used in cardiovascular disease, antihepatotoxicity, phyto-remediatory, hypoglycemic, antihypertensive, and anti-inflammatory properties. 98 , 99
Limitations
Studies investigating the chemical compositions and antimicrobial properties of Ocimum basilicum and Ocimum americanum were chosen based on the pharmaceutical application of these 2 Ocimum plants throughout this review article. On the other hand, studies related to other species of Ocimum like Ocimum gratissimum, Ocimum Campechianum, Ocimum sanctum, and others were not included in this literature review.
Conclusion
Antimicrobial resistance affects humans, animals, and plants without geographic borders or species barriers. Like in any other developing country, the prevalence of antimicrobial resistance is high and rising in Ethiopia specifically in Kellem Wollega. The use of medicinal plants is a long-standing custom that has been forced upon modern society in an attempt to understand the pharmacological activity of these plants and their benefits and drawbacks. Thus, EOs from Ocimum basilicum and Ocimum americanum are 2 types of Lamiaceae families that have abundant chemical components and antimicrobial activity. Ocimum basilicum and Ocimum americanum essential oils and crude extracts are potential sources of new antimicrobial agents due to their complex phytochemical composition and multitargeted action against a variety of strains. Authorized testing techniques are needed to evaluate the amount and eminence of active medicinal ingredients found in the final products, which are becoming increasingly common in the ethno-pharmaceutical field of diagnosing and treating disease. These tests must be conducted on human subjects through carefully planned clinical trials and validated and certified by the relevant national regulatory bodies and consumers be assured of the safety and effectiveness of herbal formulations in future. Generally, the chemical compositions and pharmacological uses of Ocimum americanum and Ocimum basilicum against a variety of bacteria resistant to antibiotics will be covered in this review article. We hope that other scientists will be inspired to collect all the information required in this field by what is missing in our systematic literature review.
Footnotes
Acknowledgments
The authors gratefully acknowledge the Department of Chemistry, Indian Institute of Technology Hyderabad and Dambi Dollo University for their invaluable support in facilitating the laboratory work for this research.
Authors’ Contributions
SF contributed to writing—original draft and conceptualization. AK, LT, and KR contributed to writing—review and editing, data curation, and conceptualization.
Data Availability
Data included in article/Supplemental material/referenced in article.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Ethics Approval
This article does not contain any studies with human or animal subjects.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
