Establishment of hairy root cultures of Salvia bulleyana Diels for production of polyphenolic compounds

Withania somnifera (L.) Dunal: Enhanced production of withanolides and phenolic acids from hairy root culture after application of elicitors

Withania somnifera (L.) Dunal is an important indigenous medicinal plant with extensive pharmaceutical potential. The root is the main source of major bioactive compounds of this plant species including withanolides, withanine, phenolic acids, etc. Hairy root culture (HRC) is a crucial method for low-cost production of active compounds on a large scale. Four different Agrobacterium rhizogenes strains have been used for the hairy root induction. Maximum transformation efficiency (87.34 ± 2.13%) was achieved with A4 bacterial strain-mediated transformed culture. The genetic transformation was confirmed by using specific primers of seven different genes. Seven HR (Hairy root) lines were selected after screening 29 HR lines based on their fast growth rate and high accumulation of withanolides and phenolic acids content. Two biotic and three abiotic elicitors were applied to the elite root line to trigger more accumulation of withanolides and phenolic acids. While all the elicitors effectively increased withanolides and phenolic acids production, among the five different elicitors, salicylic acid (4.14 mg l-1) induced 11.49 -fold increase in withanolides (89.07 ± 2.75 mg g-1 DW) and 5.34- fold increase in phenolic acids (83.69 ± 3.11 mg g- 1 DW) after 5 days of elicitation compared to the non-elicited culture (7.75 ± 0.63 mg g-1 DW of withanolides and 15.66 ± 0.92 mg g-1 DW of phenolic acids). These results suggest that elicitors can tremendously increase the biosynthesis of active compounds in this system; thus, the HRC of W. somnifera is cost-effective and can be efficiently used for the industrial production of withanolides and phenolic acids.

The Effect of Salvia tomentosa Miller Extracts, Rich in Rosmarinic, Salvianolic and Lithospermic Acids, on Bacteria Causing Opportunistic Infections

Methanolic-aqueous extracts of Salvia tomentosa Miller roots, aerial parts, and inflorescences were examined for their content of polyphenolic derivatives and the antimicrobial and cytotoxic effect. In the polyphenolic-rich profile, rosmarinic, salvianolic, and lithospermic acids along with various derivatives were predominant. A total of twenty phenolic compounds were identified using the UPLC/DAD/qTOF-MS technique. These were caffeic acid, rosmarinic acid derivatives, lithospermic acid derivatives, salvianolic acids B, F, and K derivatives, as well as sagerinic acid, although rosmarinic acid (426-525 mg/100 g of dry weight-D.W.) and salvianolic acid B (83-346.5 mg/100 g D.W.) were significantly predominant in the metabolic profile. Strong antibacterial activity of S. tomentosa extracts was observed against Staphylococcus epidermidis (MIC/MBC = 0.625 mg/mL) and Bacillus cereus (MIC = 0.312-1.25 mg/mL). The extracts showed low cytotoxicity towards the reference murine fibroblasts L929 and strong cytotoxicity to human AGS gastric adenocarcinoma epithelial cells in the MTT reduction assay. The observed cytotoxic effect in cancer cells was strongest for the roots of 2-year-old plant extracts.

Production of secondary metabolites using tissue culture-based biotechnological applications

Plants are the sources of many bioactive secondary metabolites which are present in plant organs including leaves, stems, roots, and flowers. Although they provide advantages to the plants in many cases, they are not necessary for metabolisms related to growth, development, and reproduction. They are specific to plant species and are precursor substances, which can be modified for generations of various compounds in different plant species. Secondary metabolites are used in many industries, including dye, food processing and cosmetic industries, and in agricultural control as well as being used as pharmaceutical raw materials by humans. For this reason, the demand is high; therefore, they are needed to be obtained in large volumes and the large productions can be achieved using biotechnological methods in addition to production, being done with classical methods. For this, plant biotechnology can be put in action through using different methods. The most important of these methods include tissue culture and gene transfer. The genetically modified plants are agriculturally more productive and are commercially more effective and are valuable tools for industrial and medical purposes as well as being the sources of many secondary metabolites of therapeutic importance. With plant tissue culture applications, which are also the first step in obtaining transgenic plants with having desirable characteristics, it is possible to produce specific secondary metabolites in large-scale through using whole plants or using specific tissues of these plants in laboratory conditions. Currently, many studies are going on this subject, and some of them receiving attention are found to be taken place in plant biotechnology and having promising applications. In this work, particularly benefits of secondary metabolites, and their productions through tissue culture-based biotechnological applications are discussed using literature with presence of current studies.

Effect of Light Conditions on Polyphenol Production in Transformed Shoot Culture of Salvia bulleyana Diels

Various strategies have been used to increase the efficiency of secondary metabolite production in Salvia plants. This report is the first to examine the spontaneous development of Salvia bulleyana shoots transformed by Agrobacterium rhizogenes on hairy roots and the influence of light conditions on the phytochemical profile of this shoot culture. The transformed shoots were cultivated on solid MS medium with 0.1 mg/L of IAA (indole-3-acetic acid) and 1 mg/L of m-Top (meta-topolin), and their transgenic characteristic was confirmed by PCR-based detection of the rolB and rolC genes in the target plant genome. This study assessed the phytochemical, morphological, and physiological responses of the shoot culture under stimulation by light-emitting diodes (LEDs) with different wavelengths (white, WL; blue, B; red, RL; and red/blue, ML) and under fluorescent lamps (FL, control). Eleven polyphenols identified as phenolic acids and their derivatives were detected via ultrahigh-performance liquid chromatography with diode-array detection coupled to electrospray ionization tandem mass spectrometry (UPLC-DAD/ESI-MS) in the plant material, and their content was determined using high-performance liquid chromatography (HPLC). Rosmarinic acid was the predominant compound in the analyzed extracts. The mixed red and blue LEDs gave the highest levels of polyphenol and rosmarinic acid accumulation (respectively, 24.3 mg/g of DW and 20.0 mg/g of DW), reaching two times greater concentrations of polyphenols and three times greater rosmarinic acid levels compared to the aerial parts of two-year-old intact plants. Similar to WL, ML also stimulated regeneration ability and biomass accumulation effectively. However, the highest total photosynthetic pigment production (1.13 mg/g of DW for total chlorophyll and 0.231 mg/g of DW for carotenoids) was found in the shoots cultivated under RL followed by BL, while the culture exposed to BL was characterized as having the highest antioxidant enzyme activities.

Effect of Thymbra capitata (L.) Cav. on Inflammation, Senescence and Cell Migration

Aromatic plants are reported to display pharmacological properties, including anti-aging. This work aims to disclose the anti-aging effect of the essential oil (EO) of Thymbra capitata (L.) Cav., an aromatic and medicinal plant widely used as a spice, as well as of the hydrodistillation residual water (HRW), a discarded by-product of EO hydrodistillation. The phytochemical characterization of EO and HRW was assessed by GC-MS and HPLC-PDA-ESI-MSⁿ, respectively. The DPPH, ABTS, and FRAP assays were used to disclose the antioxidant properties. The anti-inflammatory potential was evaluated using lipopolysaccharide-stimulated macrophages by assessing NO production, iNOS, and pro-IL-1β protein levels. Cell migration was evaluated using the scratch wound assay, and the etoposide-induced senescence was used to assess the modulation of senescence. The EO is mainly characterized by carvacrol, while the HRW is predominantly characterized by rosmarinic acid. The HRW exerts a stronger antioxidant effect in the DPPH and FRAP assays, whereas the EO was the most active sample in the ABTS assay. Both extracts reduce NO, iNOS, and pro-IL-1β. The EO has no effect on cell migration and presents anti-senescence effects. In opposition, HRW reduces cell migration and induces cellular senescence. Overall, our study highlights interesting pharmacological properties for both extracts, EO being of interest as an anti-aging ingredient and HRW relevant in cancer therapy.

Hairy Root Cultures as a Source of Phenolic Antioxidants: Simple Phenolics, Phenolic Acids, Phenylethanoids, and Hydroxycinnamates

Plant-derived antioxidants are intrinsic components of human diet and factors implicated in tolerance mechanisms against environmental stresses in both plants and humans. They are being used as food preservatives and additives or ingredients of cosmetics. For nearly forty years, Rhizobium rhizogenes-transformed roots (hairy roots) have been studied in respect to their usability as producers of plant specialized metabolites of different, primarily medical applications. Moreover, the hairy root cultures have proven their value as a tool in crop plant improvement and in plant secondary metabolism investigations. Though cultivated plants remain a major source of plant polyphenolics of economic importance, the decline in biodiversity caused by climate changes and overexploitation of natural resources may increase the interest in hairy roots as a productive and renewable source of biologically active compounds. The present review examines hairy roots as efficient producers of simple phenolics, phenylethanoids, and hydroxycinnamates of plant origin and summarizes efforts to maximize the product yield. Attempts to use Rhizobium rhizogenes-mediated genetic transformation for inducing enhanced production of the plant phenolics/polyphenolics in crop plants are also mentioned.

Role of Phytohormones in Biomass and Polyphenol Accumulation in Salvia bulleyana In Vitro Culture

Salvia bulleyana is a plant native to the Chinese Yunnan Province. This species has been used in traditional Chinese medicine as a substitute for Danshen (the roots of Salvia miltiorrhiza). The aim of our study was to establish an effective system for propagating S. bulleyana shoots to obtain large amounts of material rich in bioactive compounds. Phytohormones were used to regulate shoot growth and regeneration potential and influence plant secondary metabolism. The shoot tips were incubated on a Murashige and Skoog agar medium supplemented with 0.1 or 0.5 mg/L IAA (indole-3-acetic acid) and the cytokinins benzylaminopurine (BAP), meta-topoline (M-T), 6-benzylaminopurine riboside (RBAP), N-benzyl-9-(2-tetrahydropyranyl)-adenine (BPA) or kinetin, (K) at concentrations of 0.5, 1 or 2 mg/L. It was observed that the type and concentration of growth regulator significantly influenced the regeneration potential of S. bulleyana shoots. The highest multiplication rate was obtained when 0.1 mg/L IAA and 2 mg/L BPA were used. Under these conditions, 100% of shoot tips formed buds and almost seven buds/shoot per explant were obtained after five weeks. Meanwhile, the highest biomass was found for shoots growing on a medium supplemented with 0.1 mg/L IAA and 1 mg/L M-T: 1.2 g of fresh weight and 0.17 g of dry weight. However, a medium with 0.1 mg/L IAA and 2 mg/L RBAP was most favorable for bioactive phenolic acid content, with a total polyphenol level (37.7 mg/g dw) 4.5 times higher than in shoots grown on medium without growth regulators (8.23 mg/g dw). Finally, optimal conditions were selected by TOPSIS (technique for order of preference by similarity to the ideal solution); the culture of S. bulleyana grown on an MS medium containing 0.1 mg/L IAA and 1 mg/L M-T was found to be the most efficient for polyphenol accumulation and can be used for the production of medicinally relevant compounds.

Effect of Salvia Miltiorrhiza Polyphenolic Acid Injection on Improving Limb Use and Cognitive Impairment in Patients with Acute Stroke

Aims. To investigate the effect of injectable salvia polyphenolic acid on the improvement of limb movement and cognitive dysfunction in acute stroke patients. Materials and Methods. The clinical data of 90 acute stroke patients were collected for retrospective study and divided into 45 cases each in the comparison group and the observation group according to the different treatment methods; using basic treatment + salvianolic acid, the comparison group implemented conventional alteplase and butalbital treatment, and the observation group used injectable salvianolic acid treatment, to observe and compare the clinical efficacy, changes in neurological deficits, cognitive function, and motor function scores before and after treatment in the two groups. Results. The NIHSS (National Institute of Health stroke scale) score, cerebral infarct volume, NSE (neuron-specific enolase), and S100β (A neurotrophic factor) levels were reduced after treatment compared with those before treatment in this group, and the NIHSS score, cerebral infarct volume, NSE, and S100β levels in the observation group were lower than those in the comparison group after treatment, and the difference was statistically significant ( $P<0.05$ ). Compared with the clinical efficacy of the comparison group and the observation group, the treatment effect of the observation group was better than that of the comparison group, and the difference was statistically significant ( $P<0.05$ ). After treatment, the cognitive function and motor function scores of both groups were significantly improved compared with those before treatment, and the degree of improvement of each score in the observation group was significantly better than that in the comparison group ( $P<0.05$ ). During the trial, two patients in the comparison group developed a generalized rash and withdrew from the experiment, and the rash subsided after anti-allergic treatment, and no significant adverse events were observed in the remaining participants. There was no statistically significant difference in liver and kidney function and cardiac enzyme test indexes between the two groups of patients at 14 days of treatment ( $P>0.05$ ). Conclusion. Danshen polyphenolic acid for injection has definite clinical efficacy in the treatment of acute ischemic stroke, and it can effectively improve cognitive and motor functions and promote neurological recovery in patients with high safety.

In Vitro Strategy for the Enhancement of the Production of Bioactive Polyphenols in Transformed Roots of Salvia bulleyana

The underground parts of Salvia bulleyana, a rare Chinese plant species, have long been used in traditional Chinese medicine. The Rhizobium rhizogenes-transformed root culture obtained from this plant might be a promising novel source of valuable phenolics, including rosmarinic acid. The present study identifies for the first time, the optimal growth conditions of S. bulleyana hairy roots regarding production efficiency. The comprehensive optimization comprised cultivation in different basal media (B5, SH, MS, and WP) with full- and half-strength macro- and microelements, different vitamin contents (full, half, one-quarter part, and without) and sucrose concentrations (2, 3, 4, 5%), and under different light conditions: in dark, under blue LED (λ = 430 nm), red LED (λ = 670 nm), mixed blue and red LED (30%:70%), and white LED (390–670 nm). Hairy root growth and bioactive compound accumulation were also detailed every five days over the 50-day culture cycle. The optimal conditions were determined using a technique for order preference by similarity to the ideal solution (TOPSIS). The most efficient combination for root growth and polyphenol content was found to be ½SH liquid medium with half vitamin concentration and 3% sucrose when grown in the dark. The biomass yield during the growth cycle was 6.1 g (fresh weight—FW) and 0.92 g (dry weight—DW) on one Erlenmeyer flask: a 14.3-fold increase in FW and 16.1-fold increase in DW in relation to the inoculum. The highest mean total phenolic content was 93.6 mg/g DW including about 70 mg/g DW rosmarinic acid, reached on day 40 of culture; compared to roots of two-year-old plants grown under field conditions, the total phenolic acid content was four times higher and rosmarinic acid eight times higher. The obtained results place the investigated culture among the best hair root cultures for rosmarinic acid production.

The Antioxidant, Cytotoxic and Antimicrobial Potential of Phenolic Acids-Enriched Extract of Elicited Hairy Roots of Salvia bulleyana

Hairy root cultures are valuable sources of a range of phytochemicals. Among them, Salvia bulleyana root culture is a promising source of polyphenols, especially rosmarinic acid (RA), a phenolic acid depside with pleiotropic activity and a wide application in medicine and cosmetology. The aim of the study was to enhance the culture productivity by finding suitable elicitation protocol and to determine its biological potential in terms of antioxidant, anticancer and antimicrobial properties. The total content of phenols and the levels of particular constituents in root extracts were analyzed using HPLC-PDA. Among four elicitors tested (yeast extract; methyl jasmonate, MJA; trans-anethol; and cadmium chloride), MJA was found to be the most effective. The greatest boost in phenolic production (up to 124.4 mg/g dry weight) was observed after three-day treatment with MJA at 100 µM, with an almost 100% improvement compared to the controls (non-treated root culture). The hydromethanolic extract from the elicited culture exhibited strong antioxidant activity with IC₅₀ values of 11.1 µg/mL, 6.5 µg/mL and 69.5 µg/mL for DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid)) and superoxide anion radical, respectively. Moreover, in concentrations of 0.5–5 mg/mL the extract inhibited the growth of LoVo, AGS and HeLa cell lines, but was safe for the L929 cells up to the concentration of 5 mg/mL. The extract also exhibited moderate antimicrobial activity. Thus, the results confirmed that elicitation can be a beneficial strategy for increase the phenolic acid biosynthesis in hairy roots of S. bulleyana, and that such a highly productive culture can show significant biological potential.

Establishment of hairy root culture of Rubia yunnanensis Diels: Production of Rubiaceae-type cyclopeptides and quinones

Rubia yunnanensis is an important medicinal plant with various bioactive secondary metabolites. In order to reduce the dependence on wild populations of the species, we aim to establish in vitro culture system that can produce Rubiaceae-type cyclopeptides (RAs) and quinones. Agrobacterium rhizogenes-mediated transformation of stem segments of in vitro grown R. yunnanensis plants using four A. rhizogenes strains was studied and transformation conditions were optimized. Hairy roots appeared with the highest frequency (68.89%) when stem segments (with leaves) without pre-culture were immersed in A. rhizogenes A4 strain bacterial suspension for 30 min, co-cultured on Murashige and Skoog (MS) solid medium in the dark for three days, and afterwards incubated in darkness. PCR analysis of rolB and rolC genes confirmed transformed nature of six hairy root clones. The hairy roots grew rapidly, especially showing the highest accumulation of biomass in MS liquid medium compared to in vitro grown plants and calli. Histological observation of hairy root revealed anatomical difference in vascular cylinder, where the cells exhibited high mitotic activity characterized by vigorous growth. The UPLC-MS/MS analysis revealed that the amount of RAs in the hairy roots grown in ½MS liquid medium (4.611 μg g^-1 DW) was higher than that in in vitro grown plants (0.331 and 4.096 μg g^-1 DW for shoots and roots respectively) and calli (1.082 μg g^-1 DW), but still far lower than that in the roots of seed-borne plants (80.296 μg g^-1 DW). However, the hairy roots accumulated high level of quinones (2320.923 and 5067.801 μg g^-1 DW for MS and ½MS liquid media respectively), of the same order of magnitude as the roots of seed-borne plants (7409.973 μg g^-1 DW). Hairy root culture of R. yunnanensis, with high accumulation of biomass and production of quinones, may offer an attractive perspective for the production of the RAs and quinones that could be further optimized for pharmaceutical use.

Cytokinin-Based Tissue Cultures for Stable Medicinal Plant Production: Regeneration and Phytochemical Profiling of Salvia bulleyana Shoots

Salvia bulleyana is a rare Chinese medicinal plant that due to the presence of polyphenols lowers the risk of some chronic diseases especially those related to the cardiovascular system. The present study examines the organogenic competence of various combinations and concentrations of plant growth regulators to develop an efficient protocol for in vitro regeneration of S. bulleyana via leaf explants, maintaining the high production of active constituents. The purpose of the study was also to assess the possibilities of using a cytokinin-based regeneration to effectively produce therapeutic compounds. The adventitious shoot formation was observed through direct organogenesis on media with purine derivatives (meta-topolin, mT and benzylaminopurine, BAP), and through indirect organogenesis on media with urea derivatives (tidiazuron, TDZ and forchlorfenuron, CPPU). The highest regeneration frequency (95%) with 5.2 shoots per explant was obtained on leaves cultured on Murashige and Skoog (MS) medium containing 0.1 mg/L naphthalene-1-acetic acid (NAA) and 2 mg/L BAP. Following inter simple sequence repeat (ISSR) marker-based profiling, the obtained organogenic shoot lines revealed a similar banding pattern to the mother line, with total variability of 4.2–13.7%, indicating high level of genetic stability. The similar genetic profile of the studied lines translated into similar growth parameters. Moreover, HPLC analysis revealed no qualitative differences in the profile of bioactive metabolites; also, the total polyphenol content was similar for different lines, with the exception of the shoots obtained in the presence of CPPU that produced higher level of bioactive compounds. This is the first report of an effective and rapid in vitro organogenesis protocol for S. bulleyana, which can be efficiently employed for obtaining stable cultures rich in bioactive metabolites.

Abietane Diterpenoids from the Hairy Roots of Salvia corrugata

Salvia corrugata Vahl. is an interesting source of abietane and abeo-abietane compounds that showed antibacterial, antitumor, and cytotoxic activities. The aim of the study was to obtain transformed roots of S. corrugata and to evaluate the production of terpenoids in comparison with in vivo root production. Hairy roots were initiated from leaf explants by infection with ATCC 15834 Agrobacterium rhizogenes onto hormone-free Murashige and Skoog (MS) solid medium. Transformation was confirmed by polymerase chain reaction analysis of rolC and virC1 genes. The biomass production was obtained in hormone-free liquid MS medium using Temporary Immersion System bioreactor RITA®. The chromatographic separation of the methanolic extract of the untransformed roots afforded horminone, ferruginol, 7-O-acetylhorminone and 7-O-methylhorminone. Agastol and ferruginol were isolated and quantified from the hairy roots. The amount of these metabolites indicated that the hairy roots of S. corrugata can be considered a source of these compounds.

Powerful Plant Antioxidants: A New Biosustainable Approach to the Production of Rosmarinic Acid

Modern lifestyle factors, such as physical inactivity, obesity, smoking, and exposure to environmental pollution, induce excessive generation of free radicals and reactive oxygen species (ROS) in the body. These by-products of oxygen metabolism play a key role in the development of various human diseases such as cancer, diabetes, heart failure, brain damage, muscle problems, premature aging, eye injuries, and a weakened immune system. Synthetic and natural antioxidants, which act as free radical scavengers, are widely used in the food and beverage industries. The toxicity and carcinogenic effects of some synthetic antioxidants have generated interest in natural alternatives, especially plant-derived polyphenols (e.g., phenolic acids, flavonoids, stilbenes, tannins, coumarins, lignins, lignans, quinines, curcuminoids, chalcones, and essential oil terpenoids). This review focuses on the well-known phenolic antioxidant rosmarinic acid (RA), an ester of caffeic acid and (R)-(+)-3-(3,4-dihydroxyphenyl) lactic acid, describing its wide distribution in thirty-nine plant families and the potential productivity of plant sources. A botanical and phytochemical description is provided of a new rich source of RA, Satureja khuzistanica Jamzad (Lamiaceae). Recently reported approaches to the biotechnological production of RA are summarized, highlighting the establishment of cell suspension cultures of S. khuzistanica as an RA chemical biofactory.

Phytochemical Profile and Antioxidant Activity of Aerial and Underground Parts of Salvia bulleyana Diels. Plants

Plants have been used for medical purposes since ancient times. However, a detailed analysis of their biological properties and their associated active compounds is needed to justify their therapeutic use in modern medicine. The aim of the study was to identify and quantify the phenolics present in hydromethanolic extracts of the roots and shoots of the Chinese Salvia species, Salvia bulleyana. The qualitative and quantitative analyses were carried out by ultrahigh-performance liquid chromatography with electrospray ionization mass spectrometry detection (UHPLC-PDA-ESI-MS), and high-performance liquid chromatography with photodiode array (HPLC-PDA) detection. The extracts of S. bulleyana were also screened for their antioxidant activity using ferric ion (Fe³⁺) reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), diammonium 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) cation (ABTS), superoxide radical anion (O₂•–), and inhibition of lipid peroxidation assays. The S. bulleyana extracts were found to contain 38 substances, of which 36 were phenols, with a total level of 14.4 mg/g DW (dry weight) in shoots, and 23.1 mg/g DW in roots. Twenty-eight phenols were polyphenolic acids or their derivatives, the most abundant in shoots being rosmarinic acid, and in roots, salvianolic acid K followed by rosmarinic acid. The other major phenolic acids were caffeic acid, caffeoyl-threonic acids, isomers of lithospermic acid, salvianolic acid F, salvianolic acid B, and yunnaneic acid E. In addition to polyphenolic acids, nine flavonoids were detected in the shoot extract. While both extracts showed significant antioxidant activity, the shoot extract, containing both polyphenolic acids and flavonoids, demonstrated a slightly greater antioxidant potential in some of the anti-radical tests than the roots. However, the root extract proved to be slightly more effective in the lipid peroxidation inhibition test. Thus, S. bulleyana was demonstrated as a promising source of antioxidants, and worthy of further more detailed studies.