Correlated accumulation of anthocyanins and rosmarinic acid in mechanically stressed red cell suspensions of basil (Ocimum basilicum)

Exploring Plant Tissue Culture in Ocimum basilicum L

Ocimum basilicum is a well-known, economically important therapeutic plant that belongs to the family Lamiaceae. Basil is marvelous in the environment as the complete plant has been used as a conventional remedy for domestic therapy against numerous illnesses since ancient times. O. basilicum exhibited interesting biological effects due to the presence of several bioactives such as eugenol, methyl eugenol, cineone and anthocyanins. O. basilicum possesses antimicrobial, antiinflammatory, hepatoprotective, hypoglycemic, immunomodulator, antiulcerogenic, antioxidant, chemomodulatory and larvicidal activities. The oil of this plant has been found to be valuable for the cure of wasp stings, snakebites, mental fatigue, and cold. The demand of this multipurpose medicinal plant is growing day by day due to its economic importance, pharmacological properties and its numerous uses in cooking and folk medicine. Thus seeing the exciting biological activities of O. basilicum, micropropagation could be a fascinating substitute for the production of this medicinal plant because numerous plantlets can be achieved in fewer times with the assurance of genetic stability. An overview of the current study showed the use of the plant tissue culture technique for micropropagation, which is very beneficial for duplicating and moderating the species, which are problematic to regenerate by conventional methods and save them from extinction.

The exogenous application of naringenin and rosmarinic acid modulates functional traits in Lepidium sativum

BACKGROUND

Phenolic modulators have attracted attention for their potential in shaping functional traits in plants. This work investigated the impact of naringenin (Nar) and rosmarinic acid (RA) on the functional properties of Lepidium sativum leaves and roots.

RESULTS

Untargeted metabolomics identified a diverse phenolic profile, including flavonoids, phenolic acids, low molecular weight phenolics, lignans, and stilbenes. Cluster, analysis of variance multiblock orthogonal partial least squares (AMOPLS), and orthogonal projection to latent structures discriminant analysis (OPLS-DA) multivariate analyses confirmed tissue-specific modulation of bioactive compounds. The tissue was the hierarchically most influential factor, explaining 27% of observed variability, while the treatment and their interaction were statistically insignificant. Thereafter, various in vitro assays were employed to assess antioxidant capacity, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) radical scavenging activity, cupric ion reducing antioxidant capacity (CUPRAC), and ferric ion reducing antioxidant power (FRAP), metal chelating ability, and phosphomolybdenum (PMD) assays. Extracts were also tested for inhibitory effects on cholinesterase, amylase, glucosidase, and tyrosinase enzymes. RA application positively impacted antioxidant and enzyme inhibitory activities, holding valuable implications in shaping the health-promoting properties of L. sativum.

CONCLUSION

The untargeted metabolomics analysis showed a significant tissue-dependent modulation of bioactive compounds, determining no synergistic effect between applying phenolic compounds in combination. Specifically, the sole application of RA increased anthocyanins and hydroxyphenyl propanoic acid content on leaves, which was strictly related to enhancing the biological activities. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of Harvest Timing on Phytochemical Composition in Lamiaceae Plants under an Environment-Controlled System

The Lamiaceae family is widely recognized for its production of essential oils and phenolic compounds that have promising value as pharmaceutical materials. However, the impact of environmental conditions and different harvest stages on the phytochemical composition of Lamiaceae plants remains poorly understood. This study aimed to investigate the effects of harvest time on the phytochemical composition, including rosmarinic acid (RA) and volatile organic compounds (VOCs), of four Lamiaceae plants-Korean mint (AR), lemon balm (MO), opal basil (OBP), and sage (SO)-and was conducted under an environment-controlled system. Although all four plants had RA as the dominant compound, its distribution varied by species. The flowered plants, including AR and OBP, exhibited a rapid increase of RA during the transition from the vegetative stage to the reproductive stage. In contrast, non-flowered groups, including MO and SO, showed a steady increase in the content of total phenolics and RA. The main components of VOCs also differed depending on the plant, with characteristic fragrance compounds identified for each one (AR: estragole; MO: (Z)-neral and geranial; OBP: methyl eugenol, eugenol, and linalool; and SO: (Z)-thujone, camphor, and humulene). The total VOCs content was highest on the 60th day after transplanting regardless of the species, while the trends of total phenolics, RA content, and antioxidant activities were different depending on whether plant species flowered during the cultivation cycle. There was a steady increase in species that had not flowered, and the highest content and activity of the flowering period were confirmed in the flowering plant species.

Precursors and elicitor induced enhancement of cell biomass and phenolic compounds in cell suspensions of Indian basil-Ocimum basilicum (CIM-Saumya)

CIM-Saumya is an improved, methyl chavicol rich variety of Ocimum basilicum (Family-Lamiaceae), developed by Council of Scientific and Industrial Research-Central Institute of Medicinal and Aromatic Plants. This plant possesses analgesic, anti-ulcerogenic, anti-inflammatory, anti-oxidant, cardiac stimulant, Central Nervous System depressant, hepatoprotective and immunomodulator activities due to the presence of various phytoconstituents. Among them rosmarinic acid, caffeic acid and ferulic acid are the three major phenolic compounds responsible for its therapeutic utility. These compounds are produced in very low amounts in the in vivo plants. Therefore, the present study has been conducted for establishment of cell suspensions, optimization of inoculums size, growth kinetics and screening of elicitor and precursors for the accumulation of cell biomass and the production of the three important phenolic compounds in cell suspension of O. basilicum (CIM-Saumya). Leaf derived friable callus was used for establishing the cell suspension in liquid Murashige and Skoog's medium fortified with 1 g/L casein hydrolysate + 2.26 µM 2,4-dichlorophenoxyacetic acid + 0.465 µM kinetin + 2.68 µM naphthalene acetic acid. The growth kinetic analysis pattern of cell suspension revealed the maximum biomass increments (% BI = 486.7) and production of RA 8.086 mg/g dry weight was found in 30th day harvested cells. Whereas, the other two phenolic compounds i.e. ferulic acid (0.0125 mg/g dry weight) and caffeic acid (0.38 mg/g dry weight) was recorded highest on 25th day of growth cycle. In the present study, one biotic elicitor i.e. yeast extract and three precursors [peptone, tryptone and lactalbumin hydrolysate] were tested, among them, lactalbumin hydrolysate (100 mg/L; added at 16th day) treated cells recorded highest estimated phenolic compounds yield (251.5 mg/L; 6.81 fold compared to the control) and biomass increments i.e. % BI = 1207 with 1.85 fold compared to the control. The highest rosmarinic acid content i.e. 25.47 mg/g DW (4.4 fold compared to the control) and 24.42 mg/g dry weight (4.1 folds compared to the control) was noticed in 30th day harvested cells treated with yeast extract (1 g/L on 0 day) and lactalbumin hydrolysate (100 mg/L added on 16th day), respectively. While caffeic acid content (0.91 mg/g dry weight) showed 2.9 folds higher compared to the control in cells treated with peptone 200 mg/L added on 16th day of culture cycle. All the treated cells showed enhanced phenylalanine ammonia-lyase enzyme activity with highest specific activity in lactalbumin hydrolysate followed by tryptone, peptone, and yeast extract.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01316-6.

Plant morphology, physiological characteristics, accumulation of secondary metabolites and antioxidant activities of Prunella vulgaris L. under UV solar exclusion

Background

Prunella vulgaris L. has been an important medicinal plant for the treatment of thyroid gland malfunction and mastitis in China for over 2000 years. There is an urgent need to select effective wavelengths for greenhouse cultivation of P. vulgaris as light is a very important factor in P. vulgaris growth. Here, we described the effects of natural light (control) and UV solar exclusion on the morphological and physiological traits, secondary metabolites contents and antioxidant activities of P. vulgaris.

Results

The results showed that UV solar exclusion resulted in remarkable alterations to morphological and biomass traits; significantly reduced the chlorophyll a, chlorophyll b and total chlorophyll contents; significantly enhanced the ratio of chlorophyll a to b; and significantly increased the carotenoid and anthocyanin contents in P. vulgaris. UV solar exclusion significantly increased the catalase (CAT) and peroxidase (POD) activities, increased superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities and slightly decreased the glutathione (GSH) content. UV solar exclusion significantly increased the soluble sugar and H₂O₂ contents and increased the soluble protein content but significantly decreased the proline content and slightly decreased the MDA content. The secondary metabolite contents (total phenolics, rosmarinic acid, caffeic acid, hyperoside, ursolic acid and oleanolic acid) and in vitro antioxidative properties (DPPH· and ABTS·⁺scavenging activities) were significantly increased in P. vulgaris spicas under UV solar exclusion. Additionally, the total polysaccharide and total flavonoids contents were slightly increased by UV solar exclusion. The salviaflaside content was significantly reduced by UV solar exclusion.

Conclusion

Our study demonstrated that P. vulgaris activates several antioxidant defence systems against oxidative damage caused by UV solar exclusion.

Ocimum basilicum affects tracheal responsiveness, lung inflammatory cells and oxidant-antioxidant biomarkers in sensitized rats

The anti-inflammatory and antioxidant effects of Ocimum basilicum (O. basilicum) was shown previously. In the present study, the effect of O. basilicum on tracheal responsiveness (TR) to methacholine and ovalbumin (OVA), bronchoalveolar lavage fluid (BALF) levels of oxidant-antioxidant biomarkers as well as total and differential white blood cell (WBC) in sensitized rats was examined. Six groups of rats including control (group C), sensitized rats to OVA (group S), S groups treated with three concentrations of O. basilicum (0.75, 1.50, and 3.00 mg/ml) and one concentration of dexamethasone (1.25 μg/ml) (n = 8 for all groups) were studied. TR to methacholine and OVA, total WBC count, percentages of eosinophils, monocytes, neutrophils, and levels of oxidant biomarkers were significantly increased but other measured parameters were significantly decreased in group S compared to group C. TR to methacholine and OVA, percentages of eosinophils, monocytes, neutrophils, and levels of oxidant biomarkers were significantly decreased but lymphocytes and antioxidant biomarkers were significantly increased in S groups treated with dexamethasone and at least two higher concentrations of the extract compared to group S. Total WBC count was also decreased in treated S groups with dexamethasone and high extract concentration. The effect of extract on most measured parameters was significantly lower than dexamethasone treatment. The effects of two higher concentrations of the extract on most variables were significantly higher than the effect of low extract concentration. These results showed the concentration-dependent effect of O. basilicum on tracheal responses, lung inflammatory cells, and oxidant-antioxidant parameters in sensitized rats.

Green bioprinting: extrusion-based fabrication of plant cell-laden biopolymer hydrogel scaffolds

Plant cell cultures produce active agents for pharmaceuticals, food and cosmetics. However, up to now process control for plant cell suspension cultures is challenging. A positive impact of cell immobilization, such as encapsulation in hydrogel beads, on secondary metabolites production has been reported for several plant species. The aim of this work was to develop a method for bioprinting of plant cells in order to allow fabrication of free-formed three-dimensional matrices with defined internal pore architecture for in depth characterization of immobilization conditions, cell agglomeration and interactions. By using extrusion-based 3D plotting of a basil cell-laden hydrogel blend consisting of alginate, agarose and methylcellulose (alg/aga/mc), we could demonstrate that bioprinting is applicable to plant cells. The majority of the cells survived plotting and crosslinking and the embedded cells showed high viability and metabolic activity during the investigated cultivation period of 20 d. Beside its compatibility with the plant cells, the novel alg/aga/mc blend allowed fabrication of defined 3D constructs with open macropores both in vertical and horizontal direction which were stable under culture conditions for several weeks. Thus, Green Bioprinting, an additive manufacturing technology processing live cells from the plant kingdom, is a promising new immobilization tool for plant cells that enables the development of new bioprocesses for secondary metabolites production as well as monitoring methods.

A tyrosine aminotransferase involved in rosmarinic acid biosynthesis in Prunella vulgaris L

Rosmarinic acid (RA) and its derivants are medicinal compounds that comprise the active components of several therapeutics. We isolated and characterised a tyrosine aminotransferase of Prunella vulgaris (PvTAT). Deduced PvTAT was markedly homologous to other known/putative plant TATs. Cytoplasmic localisation of PvTAT was observed in tobacco protoplasts. Recombinantly expressed and purified PvTAT had substrates preference for L-tyrosine and phenylpyruvate, with apparent K m of 0.40 and 0.48 mM, and favoured the conversion of tyrosine to 4-hydroxyphenylpyruvate. In vivo activity was confirmed by functional restoration of the Escherichia coli tyrosine auxotrophic mutant DL39. Agrobacterium rhizogenes-mediated antisense/sense expression of PvTAT in hairy roots was used to evaluate the contribution of PvTAT to RA synthesis. PvTAT were reduced by 46-95% and RA were decreased by 36-91% with low catalytic activity in antisense transgenic hairy root lines; furthermore, PvTAT were increased 0.77-2.6-fold with increased 1.3-1.8-fold RA and strong catalytic activity in sense transgenic hairy root lines compared with wild-type counterparts. The comprehensive physiological and catalytic evidence fills in the gap in RA-producing plants which didn't provide evidence for TAT expression and catalytic activities in vitro and in vivo. That also highlights RA biosynthesis pathway in P. vulgaris and provides useful information to engineer natural products.

Methyl jasmonate-elicited transcriptional responses and pentacyclic triterpene biosynthesis in sweet basil

Sweet basil (Ocimum basilicum) is well known for its diverse pharmacological properties and has been widely used in traditional medicine for the treatment of various ailments. Although a variety of secondary metabolites with potent biological activities are identified, our understanding of the biosynthetic pathways that produce them has remained largely incomplete. We studied transcriptional changes in sweet basil after methyl jasmonate (MeJA) treatment, which is considered an elicitor of secondary metabolites, and identified 388 candidate MeJA-responsive unique transcripts. Transcript analysis suggests that in addition to controlling its own biosynthesis and stress responses, MeJA up-regulates transcripts of the various secondary metabolic pathways, including terpenoids and phenylpropanoids/flavonoids. Furthermore, combined transcript and metabolite analysis revealed MeJA-induced biosynthesis of the medicinally important ursane-type and oleanane-type pentacyclic triterpenes. Two MeJA-responsive oxidosqualene cyclases (ObAS1 and ObAS2) that encode for 761- and 765-amino acid proteins, respectively, were identified and characterized. Functional expressions of ObAS1 and ObAS2 in Saccharomyces cerevisiae led to the production of β-amyrin and α-amyrin, the direct precursors of oleanane-type and ursane-type pentacyclic triterpenes, respectively. ObAS1 was identified as a β-amyrin synthase, whereas ObAS2 was a mixed amyrin synthase that produced both α-amyrin and β-amyrin but had a product preference for α-amyrin. Moreover, transcript and metabolite analysis shed light on the spatiotemporal regulation of pentacyclic triterpene biosynthesis in sweet basil. Taken together, these results will be helpful in elucidating the secondary metabolic pathways of sweet basil and developing metabolic engineering strategies for enhanced production of pentacyclic triterpenes.

Untargeted metabolomics: an emerging approach to determine the composition of herbal products

Natural remedies, such as those based on traditional Chinese medicines, have become more popular also in western countries over the last 10 years. The composition of these herbal products is largely unknown and difficult to determine. Moreover, since plants respond to their environment changing the metabolome, the composition of plant material can vary depending on the plant growth conditions.

However, there is a growing need of a deeper knowledge on such natural remedies also in view of the growing number of reports of toxicity following the consumption of herbal supplements. Untargeted metabolomics is a useful approach for the simultaneous analysis of many compounds in herbal products. In particular, liquid chromatography/mass spectrometry (LC-MS) can determine presence, amount and sometime structures of plant metabolites in complex herbal mixtures, with significant advantages over techniques such as nuclear magnetic resonance (NMR) spectroscopy and gas chromatography/mass spectrometry (GC-MS).

Phytochemical screening and evaluation of cardioprotective activity of ethanolic extract of Ocimum basilicum L. (basil) against isoproterenol induced myocardial infarction in rats

BACKGROUND AND THE PURPOSE OF THE STUDY

The objectives of the present study were phytochemical screening and study of the effects of ethanolic extract of aerial parts of Ocimum basilicum (basil) on cardiac functions and histopathological changes in isoproterenol-induced myocardial infarction (MI).

METHODS

The leaves of the plant were extracted with ethanol by maceration and subjected to colorimetry to determine flavonoids and phenolic compounds. High-performance TLC analysis and subsequent CAMAG's TLC scanning were performed to quantify rosmarinic acid content. Wistar rats were assigned to 6 groups of normal control, sham, isoproterenol, and treatment with 10, 20, and 40 mg/kg of the extract two times per day concurrent with MI induction. A subcutaneous injection of isoproterenol (100 mg/kg/day) for 2 consecutive days was used to induce MI.

RESULTS

Phytochemical screening indicated the presence of phenolic compounds (5.36%) and flavonoids (1.86%). Rosmarinic acid was the principal phenolic compound with a 15.74% existence. The ST-segment elevation induced by isoproterenol was significantly suppressed by all doses of the extract. A severe myocardial necrosis and fibrosis with a sharp reduction in left ventricular contractility and a marked increase in left ventricular end-diastolic pressure were seen in the isoproterenol group, all of which were significantly improved by the extract treatment. In addition to in-vitro antioxidant activity, the extract significantly suppressed the elevation of malondialdehyde levels both in the serum and the myocardium.

CONCLUSION

The results of the study demonstrate that Ocimum basilicum strongly protected the myocardium against isoproterenol-induced infarction and suggest that the cardioprotective effects could be related to antioxidative activities.

Metabolomic analysis reveals that the accumulation of specific secondary metabolites in Echinacea angustifolia cells cultured in vitro can be controlled by light

Echinacea angustifolia cell suspension cultures are usually grown and maintained in the dark, but we also exposed cells to light for one culture cycle (14 days) and then compared the metabolomes of dark-grown and illuminated cells by liquid chromatography-mass spectrometry. Among 256 signals, we putatively identified 159 molecules corresponding to 56 different metabolites plus their fragments, adducts and isotopologs. The E. angustifolia metabolome consisted mainly of caffeic acid derivatives, comprising (a) caffeic acid conjugated with tartaric, quinic and hexaric acids; and (b) caffeic acid conjugated with hydroxytyrosol glycosides (e.g., echinacoside, verbascoside and related molecules). Many of these metabolites have not been previously described in E. angustifolia, which currently lacks detailed metabolic profiles. Exposure to light significantly increased the levels of certain caffeic acid derivatives (particularly caffeoylquinic acids and hydroxytyrosol derivatives lacking rhamnose residues) and reduced the level of hydroxytyrosol derivatives with rhamnose residues, revealing that light specifically inhibits the rhamnosylation of caffeoyl phenylethanoid glycosides. These results are significant because they suggest that the metabolic profile of cell cultures can be manipulated by controlling simple environmental variables such as illumination to modulate the levels of potentially therapeutic compounds.

Rosmarinic acid content in basil plants grown in vitro and in hydroponics

The accumulation of selected caffeic acid derivatives (CADs), in particular rosmarinic acid (RA), was investigated in different tissues (leaves, roots and plantlet shoots) of sweet basil (Ocimum basilicum L.) plants grown either in vitro or in hydroponic culture (floating system) under greenhouse conditions. Two cultivars with green leaves (Genovese and Superbo) and one with purple leaves (Dark Opal) were tested. The content of CADs in HCl-methanol extracts was determined by HPLC. LC-MS and LC-MS-MS were used to confirm the identification of the metabolites of interest. Apart from rosmarinic acid (RA) and a methylated form of this substance, no other CADs were detected at significant level in any of the analyzed samples. The content of RA ranged approximately from 4 to 63 mg/g DW, depending on the growing system. The highest RA content was found during the in vitro multiplication, in the acclimatized plants and in the roots of hydroponically-grown seedlings at full bloom. In vitro, 6-benzyladenine reduced the accumulation of RA in purple-leaf Dark Opal cultivar, but an opposite effect of this growth regulator was observed in the green-leaf genotypes. Our findings suggest the possibility to scale-up RA production by means of in vitro or hydroponic culture of sweet basil.