Concept: Ocimum basilicum
Lipophilic flavonoids found in the Lamiaceae exhibit unusual 6- and 8-hydroxylations whose enzymatic basis is unknown. We show that crude protein extracts from peltate trichomes of sweet basil (Ocimum basilicum L.) cultivars readily hydroxylate position 6 of 7-O-methylated apigenin, but not apigenin itself. The responsible protein was identified as a P450 monooxygenase from the CYP82 family, a family not previously reported to be involved in flavonoid metabolism. This enzyme prefers flavones but also accepts flavanones in vitro, and requires a 5-hydroxyl in addition to a 7-methoxyl residue on the substrate. A peppermint (Mentha x piperita) homolog displayed identical substrate requirements, suggesting that early 7-O-methylation of flavones might be common in the Lamiaceae. This hypothesis is further substantiated by the pioneering discovery of 2-oxoglutarate-dependent flavone demethylase activity in basil, which explains the accumulation of 7-O-demethylated flavone nevadensin.
Glucocorticoid-induced osteoporosis (GIO) is one of the serious side effects which have become the most common secondary osteoporosis. The purpose of this study is to evaluate the effect of aqueous extract of parsley, basil and chicory on glucocorticoid-induced osteoporosis in rats.
Numerous aromatic plant species produce high levels of monoterpenols, using geranyl diphosphate (GPP) as a precursor. Sweet basil (Ocimum basilicum) geraniol synthase (GES) was used to evaluate the monoterpenol profiles arising from heterologous expressions in various plant models. Grapevine (Vitis vinifera) calli were transformed using Agrobacterium tumefasciens and the plants were regenerated. Thale cress (Arabidopsis thaliana) was transformed using the floral dip method. Tobacco (Nicotiana benthamiana) leaves were agro-infiltrated for transient expression. Although, as expected, geraniol was the main product detected in the leaves, different minor products were observed in these plants (V. vinifera: citronellol and nerol; N. benthamiana: linalool and nerol; A. thaliana: none). O. basilicum GES expression was also carried out with microbial system yeasts (Saccharomyces cerevisiae) and Escherichia coli. These results suggest that the functional properties of a monoterpenol synthase depend not only on the enzyme’s amino-acidic sequence, but also on the cellular background. They also suggest that some plant species or microbial expression systems could induce the simultaneous formation of several carbocations, and could thus have a natural tendency to produce a wider spectrum of monoterpenols.
Increasing salinity tolerance and water-use efficiency in crop plants are two major challenges that agriculture must face in the next decades. Many physiological mechanisms and molecular components mediating crop response to environmental stresses have been identified. However, the functional inter-links between stress adaptation responses have not been completely understood. Using two basil cultivars (Napoletano and Genovese) with contrasting ability to respond to salt stress, here we demonstrate that reduced stomatal density, high ascorbate level and polyphenol oxidase (PPO) activity coordinately contribute to improve basil adaptation and water use efficiency (WUE) in saline environment. The constitutively reduced stomatal density was associated with a “delayed” accumulation of stress molecules (and growth inhibiting signals) such as abscisic acid (ABA) and proline, in the more tolerant Genovese. Leaf volatile profiling also revealed cultivar-specific patterns, which may suggest a role for the volatile phenylpropanoid eugenol and monoterpenes in conferring stress tolerance via antioxidant and signalling functions.
The toxicity of mosquito larvicidal activity of leaf essential oil and their major chemical constituents from Ocimum basilicum were evaluated against Culex tritaeniorhynchus, Aedes albopictus and Anopheles subpictus. The chemical composition of the leaf essential oil was analyzed using gas chromatography-mass spectroscopy. GC-MS revealed that the essential oil of O. basilicum contained 20 compounds. The major chemical components identified were linalool (52.42%), methyl eugenol (18.74%) and 1, 8-cineol (5.61%). The essential oil had a significant toxic effect against late third-stage larvae of Cx. tritaeniorhynchus, Ae. albopictus and An. subpictus with an LC(50) values of 14.01, 11.97 and 9.75 ppm and an LC(90) values of 23.44, 21.17 and 18.56 ppm, respectively. The results could be useful in search for newer, safer, and more effective natural larvicidal agents against Cx. tritaeniorhynchus, Ae. albopictus and An. subpictus.
The considerable therapeutical problems of persistent infections caused by multidrug-resistant bacterial strains constitute a continuing need to find effective antimicrobial agents. The aim of this study was to demonstrate the activities of basil (Ocimum basilicum L.) and rosemary (Rosmarinus officinalis L.) essential oils against multidrug- resistant clinical strains of Escherichia coli. A detailed analysis was performed of the resistance of the drug to the strains and their sensitivity to the tested oils. The antibacterial activity of the oils was tested against standard strain Escherichia coli ATCC 25922 as well as 60 other clinical strains of Escherichia coli. The clinical strains were obtained from patients with infections of the respiratory tract, abdominal cavity, urinary tract, skin and from hospital equipment. The inhibition of microbial growth by both essential oils, presented as MIC values, were determined by agar dilution. Susceptibility testing to antibiotics was carried out using disc diffusion. The results showed that both tested essential oils are active against all of the clinical strains from Escherichia coli including extended-spectrum β-lactamase positive bacteria, but basil oil possesses a higher ability to inhibit growth. These studies may hasten the application of essential oils in the treatment and prevention of emergent resistant strains in nosocomial infections.
The purpose of this study was to evaluate the role of 638-nm and 665-nm LEDs on changes of antioxidants of basil (Ocimum basilicum) and parsley (Petroselinum crispum), and to assess the effect of light quality on antioxidative status. Plants were grown in peat substrate for 19 days (21/17 ±2°C, 16 h). Experiments were performed in (I) a controlled-environment: B455,R638,R665,FR731(control); B455,R*638,R665,FR731; B455,R638,R*665,FR731; R638; R665 (B-blue, R- red, FR-far-red light). PPFD was set from 231 during growth, upto 300 μmol m-2 s-1 during 3-day treatment changing R638 or R665 PPFD level; in (II) greenhouse (November): high-pressure sodium lamps (HPS) (control-300 μmol m-2s-1); and HPS + 638 (HPS generated 90 and red LEDs-210 μmol m-2s-1). In general, under supplemental or increased red 638 nm light, amounts of tested antioxidants were greater in basil, whereas sole 665 nm or sole 638 nm is more favourable for parsley. Increased or supplemental red light significantly increased contents of phenolics, α-tocopherol, ascorbic acid and DPPH• but suppressed accumulation of lutein and β-carotene in basil, whereas an increase of β-carotene and DPPH• was observed in parsley. Hereby, the photoresponse of antioxidant compounds suggests that photoprotective mechanism is stimulated by both light-dose-dependent and wavelength-dependent reactions.
Natural products, known for their medicinal properties since antiquity, are continuously being studied for their biological properties. In the present study, we analyzed the composition of the volatile preparations of essential oils of the Greek plants Ocimum basilicum (sweet basil), Mentha spicata (spearmint), Pimpinella anisum (anise) and Fortunella margarita (kumquat). GC/MS analyses revealed that the major components in the essential oil fractions, were carvone (85.4%) in spearmint, methyl chavicol (74.9%) in sweet basil, trans-anethole (88.1%) in anise, and limonene (93.8%) in kumquat. We further explored their biological potential by studying their antimicrobial, antioxidant and antiproliferative activities. Only the essential oils from spearmint and sweet basil demonstrated cytotoxicity against common foodborne bacteria, while all preparations were active against the fungi Saccharomyces cerevisiae and Aspergillus niger. Antioxidant evaluation by DPPH and ABTS radical scavenging activity assays revealed a variable degree of antioxidant potency. Finally, their antiproliferative potential was tested against a panel of human cancer cell lines and evaluated by using the sulforhodamine B (SRB) assay. All essential oil preparations exhibited a variable degree of antiproliferative activity, depending on the cancer model used, with the most potent one being sweet basil against an in vitro model of human colon carcinoma.
The basil (Ocimum spp.) genus maintains a rich diversity of phenotypes and aromatic volatiles through natural and artificial outcrossing. Characterization of population structure and genetic diversity among a representative sample of this genus is severely lacking. Absence of such information has slowed breeding efforts and the development of sweet basil (Ocimum basilicum L.) with resistance to the worldwide downy mildew epidemic, caused by the obligate oomycete Peronospora belbahrii. In an effort to improve classification of relationships 20 EST-SSR markers with species-level transferability were developed and used to resolve relationships among a diverse panel of 180 Ocimum spp. accessions with varying response to downy mildew.
The genus Ocimum (Labiatae) comprises 30 species found in tropical and subtropical regions of the planet, of which species O. basilicum L. and O. gratissimum are widely used in food and traditional medicine. Phytochemical studies on Ocimum have revealed a number of essential oil chemotypes, for example, eugenol, methyl chavicol, linalool, and methyl cinnamate. Since essential oils are commercially assessed according to their content, the aim of this study was to develop a simple and precise method for their qualitative and quantitative analysis using NMR spectroscopy combined with chemometrics. Seven essential oils from different species of Ocimum, an unknown sample, and a commercial sample were evaluated and the results compared to those from established and precise GC-MS and GC-FID methods. Chemometric evaluation from both1H NMR and GC-MS data revealed three chemotypes: eugenol for O. gratissimum, O. micranthum, and O. tenuiflorum; estragole for O. basilicum, O. basilicum var. purpuracens, and O. selloi; and methyl cinnamate for O. americanum. The unknown and commercial species were classified as cinnamate and eugenol chemotypes, respectively. Despite the corroborating results, the chemometric analysis revealed the higher robustness (better adjustment) of the1H NMR model compared to the GC-MS method in terms of certain statistical parameters. The1H NMR method allows for the detection and quantification of organic compounds in a complex mixture without the need for certified standard compounds. Although GC-MS and GC-FID were able to detect five compounds not observed by NMR spectroscopy, the four most important metabolites (eugenol, estragole, methyl cinnamate, and eucalyptol) were more readily detected and quantified by1H NMR.