Research Progress on Chemical Composition and Clinical Effect of Ocimum basilicum

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Bozhou Vocational & Technical College, Bozhou 236800, China

AbstractOcimum basilicum is a common herb well known for its importance for ornamental and therapeutic purposes. Chemical components that have been isolated from O. basilicum plants include terpenoids, alkaloids, flavonoids, tannic acid, saponin glycosides, and ascorbic acid. O. basilicum has liver protection, immune regulation, anti-hyperglycemia, hypolipidemic, anti-toxin, anti-inflammatory, anti-bacterial and anti-fungal effects. This paper aims to review the latest progress in phytochemical research and pharmacological research of O. basilicum, which will assist various practitioners and clinicians in understanding the traditional and modern uses of O. basilicum.

Key wordsOcimum basilicum, Phytochemical research, Pharmacological research

1 Introduction

Chinese herbal medicine, also called botanical medicine, refers to using seeds, fruits, roots, leaves, bark or flowers of plants for medicinal purposes. China has a long history of use of herbal medicines. With the improvement in the analysis and quality control and the progress in clinical research, the value of Chinese herbal medicine in the treatment and prevention of diseases is becoming higher and higher[1].

2 Classification

Ocimum belongs to the family Lamiaceae. There are about 35 kinds of aromatic annual and perennial herbs and shrubs, which are mainly native to the tropical and warm temperate regions of the world, including some important medicinal species[2].

2.1 Ocimum americanum

O.americanumis produced in tropical Africa. It is called hairy or ancient basil, and is annual herbaceous plant. Ued in medicine,O.americanumshow antibacterial and antioxidant activity[3].O.americanumcontains volatile oils, flavonoids, carbohydrates, phytosterols, tannins and fixed oils.

2.2 O. basilicum

O.basilicumis herbaceous plant that can be used for cooking. Many cooking and ornamental basil varieties and species have hybrids.O.basilicumhas a strong flavor similar toIlliciumverum, is a common ingredient in Thai food, and is often used for season curry and frying potato chips.O.basilicumhas been widely applied as a folk remedy for a large number of diseases, including cancer, convulsions, deafness, diarrhea, epilepsy, gout, snoring, impotence, confusion, nausea, sore throat, toothache and whooping cough, and is also usually used as a mosquito repellent[4].

2.3 Ocimum gratissimum

O.gratissimum, also known as African basil, or Hawaiian wild basil, has antibacterial, anti-diabetic, anti-tumor, anti-cancer, diarrhea, anti-fertility, hepatoprotective and therapeutic effects of gastrointestinal diseases[5].

2.4 Ocimum micranthum

O.micranthum, also known as Amazon basil, is a South American variety commonly used for the odor of Ayahuasca (entheogenic brew made out of Banisteriopsis caapi vine, often in combination with various other plants. It can be mixed with the leaves of Chacruna or Chagropanga, dimethyltryptamine (DMT)-containing plant species). It is reported that it helps to avoid poor vision.O.micranthumhas antibacterial, antiprotozoal and antioxidant activity[6].

2.5 Ocimum tenuiflorum

O.tenuiflorum, as an aromatic plant of the Labiatae family, is widely distributed throughout the tropical areas and is widely used as a weed for cultivated plants.O.tenuiflorumis an erect, multi-branched sub-shrub, 30-60 cm tall, has hairy stems and simple opposite green leaves, and has strong aroma. Leaves have petiole, are ovate, up to 5 cm long, and usually slightly toothed. Flowers are purplish in the slender racemes of dense spirals. There are two main morphological types: green leaf (Sri or Lakshmi tulsi) and purple leaf (Krishna tulsi). It has antioxidant activity and is also used for memory improvement.

2.6 Ocimum sanctum

In Hindi,O.sanctumis called tulsi, in English, it is called St. Basil. It is an upright, soft and furry aromatic herb, it can be found in various parts of India.O.sanctumis often planted in garden. In the culture process, there are two types of St. Basil, namely, Krishna tulsi and Sri tulsi & tulsi. St. Basil is considered a sacred plant by Hindus and used as a medicinal plant for various diseases in the daily work of Indian families. It has some medical functions such as anti-cancer, anti-fertility, anti-diabetic and treatment of other diseases[7].

2.7 Ocimum kilimandscharicum

Economically,O.kilimandscharicumis an important medicinal perennial herb widely distributed in East Africa, India and Thailand, and widely planted in the tropical areas.

3 Botanical characteristics

O.basilicumis an erect branching herb, 0.6-0.9 m tall, glabrous, more or less pubescent. Stems and branches are green or sometimes purplish.O.basilicumleaves are simple, 2.5-5.0 cm or longer, ovate, entire or more or less dentate or lobes cuneate and entire base. The petiole is 1.3-2.5 cm long. The leaves have many volatile oils that secrete strong flavors like oil glands. There are spirally dense racemes, where the end is usually much longer than lateral. Bracts are culm, shorter than calyx, ovate and acute. Calyx is 5 mm long, expanded in fruit period, and has very short pedicels. The lower lip of its two central teeth is longer than the round upper lip. The 8-13 mm long corolla is white, pink or purplish, glabrous or more or less pubescent. The upper filaments slightly applied with stamens are arranged in a toothed manner at the base. Small nuts are approximately 2 mm long, elliptic, black and dentate. Flowers have five sepals, and remain fused into a two-lip calyx[8].

Basil can be propagated through seeds and transplanting. Its flowers have pedicels, up to 18 inches long. Basil thyme seeds are black, very small, oval, about 1 mm in the middle and 2 mm in length. Seedlings are kept in the nursery and transplanted to the farm. Once shrubs are set up, they can be harvested three times a year for more than three years. It needs well-drained soil, but it performs well in clay and sandy soil, with an average annual rainfall of 1 250 mm, a fairly high temperature and a height of up to 900 mm.

4 Chemical properties

4.1 Chemical composition

Seed oil ofO.basilicumcontains α-pinene (1.23%), terpene (7.32%), β-myrcene (1.58%), ethylamyl-methanol (0.88%), 1-purelyne (0.26%), α-terpinene (0.33%) (0.62%), dl-limonene (13.56%), 1,8-octene (0.85%), β-omega (2.00%), γ-terpinene (0.88%), trans-arsenene (0.49%), α-terpinene (1.33%), linalool (1.70%), cis salicylic acid (0.47%), camphor (56.07%), terpineol (3.50%), myrtenol (1.24%), trans caryophyllene (0.33%), germarcrene-d (0.43%). Ground parts ofO.basilicumcontains α-pinene (1.23%), terpene (7.32%), β-myrcene (1.58%), 1-purelyne (0.26%), α-terpinene (0.33%), p- (0.62%), dl-limonene (13.56%), 1,8-octene (0.85%), β-omega (2.00%), γ-terpinene (0.88%), trans-arsenene (0.47%), terpinene (1.33%), trans-purelyne (0.49%), linalool (1.70%), camphor (56.07%), terpinen-4-ol (3.50%), myrtenol (1.24%), trans caryophyllene (0.33%), and germacrene D (0.43%)[9]. Aqueous extract ofO.basilicumleaves contains camphor, 1,8-cineole, limonene, trans-caryophyllene, terpene, myrtenol, α-terpineol, endo-borneol, and linalool[10].O.basilicumleaves also contain flavonoids, tannins, saponins, sterols, carbohydrates, proteins and triterpenoids. These chemical components mainly adjust various biological activities.

The chemical composition depends on its life stage and cultivation site.O.basilicumcontains different amounts of essential oils. Hussainetal.[11] studied the composition ofO.basilicuminfluenced by summer, autumn, winter and spring. They found that the content of essential oils is different in different seasons. The content of essential oils inO.basilicumwas the highest in winter (0.8%) and significantly declined to 0.5% in summer (P<0.05). The content of oxygenated monoterpenoids was higher in the samples collected in winter (68.9%), and the content in summer was higher in sesquiterpene olefins (24.3%). There was a significant difference in the content of most chemical components in different seasons (P<0.05).

4.2 Drying method

In a study carried out by Polatc[12],O.basilicumwas dehydrated using five different drying methods (contact drying, oven drying, shade open atmosphere drying, sun drying and microwave drying). For all drying methods, drying properties (drying time, final moisture content), drying kinetics, color analysis, and essential oil analysis were performed. The results of the study indicate the air heated to 45-55℃ is suitable for dryingO.basilicum.

4.3 Extraction method

Soran[13] used three different extraction methods (impregnation, ultrasonic and microwave field extraction) to extract essential oils fromO.basilicum. The extract was analyzed by thin-layer chromatography / high performance thin-layer chromatography (TLC/HPTLC) technology, to obtain fingerprint information. A gas chromatograph with flame ionization detection was used to characterize the extraction efficiency and to identify terpenoid bioactive compounds. It can be concluded that the most effective extraction techniques are microwave and ultrasonic impregnation. The best extraction solvent system is ether + ethanol (1∶1,v/v).

4.4 Aroma characteristics

Klimankovaetal.[14] analyzed the aroma characteristics of fiveO.basilicumsamples. A headspace solid-phase microextraction method coupled with gas chromatography-ion trap mass spectrometry (GC-IMS) has been developed and applied to organic and conventional conditions from two kinds of volatile compounds grown on two kinds ofO.basilicum. Full-scale two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (TOFMS) was used to confirm the identity of the volatile components ofO.basilicumheadspace extracted by solid-phase microextraction. Linalool, methylcamphorol, eugenol, bergamot and methyl cinnamate are the main volatile components, and it has been provided that their relative contents can distinguish the cultivars examined. Compared to freshO.basilicumleaves, some sesquiterpenes in dried and frozen leaves have relatively low relative amount of hydrocarbon benzene compounds and monoterpenoid hydrocarbons. Sensory analysis of all tested samples demonstrated differences between the evaluated varieties.

5 Traditional functions

In traditional medicine,O.basilicumis widely used to treat colds, coughs, abdominal pain, measles, and diarrhea.O.basilicumleaves treat chest tightness, coughs and colds through sniffing the broken leaves or breathing boiling vapors of leaves. Indoctrination of leaves is a method for treating measles. Essential oils have a biologically active ingredient that can act as an insect repellent, especially for mosquitoes and storage pests. Some local farmers mix the stored food with driedO.basilicumleaves to prevent damage of stored foods from pests[15]. It shows antibacterial and antioxidant activity. Besides, it is also used for viral infections, odor, anorexia and wound healing. Put into pot or cooked to boiling,O.basilicumcan generate aroma. In the Mediterranean area,O.basilicumis used for decoration.

6 Pharmacological effects

6.1 Anti-oxidant activity

In the action of UV-B, the regulation of enzyme and non-enzymatic antioxidants was observed inO.kilimandscharicum. The changes of lipid peroxidation and free radical content in leaves were studied. Lipid peroxidation as measured by MDA levels increased with the increase in the dose of UV-B and was higher at higher doses of radiation. Restored leaves showed lower MDA content and hydroxyl radicals. The content of ascorbic acid, flavonoids and proline in leaves restored from UV-B was highly increased. The results indicate that a higher ability to scavenge free radicals and a more effective antioxidative capacity use thiobarbituric acid assays in the liver and muscle assay system of the ovarian model. This shows thatO.basilicumhas great potential as an antioxidant due to the rich flavonoids[16]. The protective effects of essential oils and water soluble extracts from three different varieties of sweetO.basilicumhave been evaluated in cultured cardiomyocytes. According to experimental results, (i) antioxidant activityinvitrocan not predict biological activity; (ii)O.basilicumcan produce extracts with significantly different protective effects compared with compositions and extraction techniques. In addition, variations among different cultivars have also been discovered.

6.2 Antibacterial activity

Essential oils of the ground parts ofO.basilicumshow antimicrobial activity against Gram-positive bacteria (Staphylococcusaureus,Enterococcusfaecalis), Gram-negative bacteria (Escherichiacoli,Pseudomonasaeruginosa) andCandidaalbicans[17].O.basilicumroots have significant antibacterial activity against a variety of bacteria, such asBacillusoligosaccharides,Bacillusstearothermophilus,Bacillusthuringiensis,Bacillussubtilis,Lactobacilluscasei,Lactobacillusplantarum,Micrococcusluteus,S.aureus,etc.

6.3 Analgesic activity

The analgesic activity of methanol extract ofO.basilicumwas evaluated by tail immersion in Swiss mice. The extract showed the analgesic activity equivalent to standard drug aspirin at a concentration of 200 mg/kg[18].

6.4 Cardiovascular diseases

The antihypertensive and antithrombotic effects ofO.basilicumon prostaglandins were examined.O.basilicumand its extracts increased 6-keto-PGF1α in a dose-dependent and time-dependent manner and reduced the production of PGE2 and TXB2. This may indicate simultaneous inhibition of COX-2 and stimulation of endothelium COX-1. In this regard, the butanol seems to be more promising[19].

6.5 Anti-hepatotoxicity

The protective effect of the methanol extract ofO.basilicumon hematological toxicity of benzene-induced Swiss albino mice was evaluated. The results showed that the secondary metabolites of the methanol extract ofO.basilicumleaves, which is mainly composed ofO.basilicuvolatile oil and monoterpenoid geraniol and its oxidized citral, could regulate the cell cycle disorder and hematological abnormalities induced by benzene in mice.

From the methylene chloride extract of the hairy root culture ofO.basilicum(Lamiaceae), six species identified as Betula Linn., oleanolic acid, ursolic acid, 3-epischadic acid, alphitolic and euscaphic acid were isolated. All tested compounds showed hepatoprotective activity comparable to oleanolic acid and ursolic acid[20].

6.6 Hypoglycemic effect

The hypoglycemic activityinvitroofO.basilicumextract was studied. It arrived at the conclusion thatO.basilicumextracts that inhibit the activity of antioxidants and possibly α-glucosidases and α-amylases provide positive benefits for the control of diabetes[21].

6.7 Antihypertensive effect

The possible antihypertensive effects ofO.basilicumextracts in renovascular hypertensive rats were examined. The effect ofO.basilicumon blood pressure, cardiac hypertrophy, and ET is consistent with the role of ET invertase, and this is worthy of further investigation[22].

6.8 Vasodilation and antiplatelet effect

The endothelium-dependent vasodilation and antiplatelet aggregation activities ofO.basilicumextracts were studied. The results showed that compared with NCG, HCD statistics reduced vasorelaxation in HCG (P<0.001) and increased vascular response to phenylephrine (P<0.02).O.basilicumas a medicinal plant may be beneficial to the cardiovascular system[23].

6.9 Anti-inflammatory effects

We evaluated the effect ofO.basilicumfruit oil on acute inflammatory reaction in male Wistar rats induced by rosin oil.O.basilicumfruit can significantly reduce the total white blood cell count, the percentage of monocytes, activate phagocytic cells, and have a certain inhibitory effect on NO synthesis. Compared with diclofenac,O.basilicumtincture has less inhibition of all parameters.O.basilicumhas an important anti-inflammatory effect on the acute bone marrow reaction and has a certain inhibitory effect on NO synthesis[24].

6.10 Antithrombotic effects

The effects of aqueous extracts ofO.basilicumon platelet aggregation and experimental thrombosis were studied.O.basilicumhas an inhibitory effect on ADP and thrombin-induced platelet aggregation in a dose-dependent manner and has an in vivo antithrombotic effect, which gradually develops within 7 d, and disappears within 3-7 d. It is now necessary to further characterize the active components[25].

7 Discussions

In recent years, traditional medicine has become a potential source of drugs fore treatment of chronic, degenerative, environmental, lifestyle and stress-related diseases. The idea of using medicinal plants to treat human diseases is not new, and the use of traditional medicinal plants is still very popular in many developing countries.O.basilicumis a very important medicine that has traditionally been used to treat many diseases. The wide scope and diversity ofO.basilicummay be the result of the synergistic effect of its phytochemical composition. In this paper, we reviewed literature ofO.basilicum, to provide evidence-based scientific verification for some of the behavioral and therapeutic uses ofO.basilicum. However, there is no detailed description of compounds related to these activities. It is necessary to make further study, to satisfy the demands of research and development.