Differential physiological and biochemical responses under variable culture conditions in micro-propagated Solenostemon scutellarioides: an important ornamental plant

Plant In Vitro Cultures of Coleus scutellarioides (L.) Benth. "Electric Lime" and Possibilities of Modification in the Biosynthesis of Volatile Compounds

Coleus scutellarioides (L.) Benth. is a globally spread species, known for its characteristic spectacularly colorful leaves of decorative value. Thanks to its rich chemical composition, the plant is used in ethnopharmacology, and it is also regarded as having high medicinal potential. The application of in vitro cultures enables the acquisition of homogeneous certified material of high quality. Additionally, excluding the effect of biotic and abiotic factors on the plants is a way to fully recognize the influence of phytohormones on the plant morphology and the biosynthetic pathways of compound production. The best way to grow C. scutellarioides "Electric Lime" under in vitro conditions is to use the basic MS medium (Murashige and Skoog medium), enriched with naphthyl-1-acetic acid at a concentration of 0.5 mg dm-3. The analysis of volatile compounds demonstrated that the content of volatile compounds in the plants cultivated under in vivo conditions was expressed at a level of 2848.59 µg g-1, whereas in the plants bred in vitro without supplementation with phytohormones, the level was 8191.47 µg g-1. The highest content was noted for copaene, α-pinene, 1-octene-3-ol, α-selinene, sabinen, γ- and δ-cadinene, 3-octanol, and β-pinene. Aroma profiling revealed a lack of boranyl acetate, 2-hexenal, and 2-hexen-1-ol in the plants cultivated under in vivo conditions. Differences were found in the volatile composition between plants bred in vivo and in vitro, with the most significant recorded for the contents of 1-octen-3-ol and 3-octanol. The addition of plant growth regulators into the basic medium under in vitro conditions affected the percentage ratio and contents of specific compounds in plant tissues. The most intense biosynthesis of volatile compounds took place in the plants cultivated on the medium enriched with NAA at 10,579.11 µg g-1, whereas the least intense was noted for plants cultivated on the medium supplemented with BA, where it was recorded at the level of 5610.02 µg g-1. So far, there has been no research published which would pertain to the profiling of volatile compounds performed using the SPME (solid-phase microextraction) technique. Moreover, the very few studies conducted on the chemical composition of these compounds do not mention the specific variety of C. scutellarioides under analysis.

Biological Properties of Extracts Obtained from In Vitro Culture of Plectranthus scutellarioides in a Cell Model

Plectranthus scutellarioides (L.) R.Br. is a medicinal plant that has long been used in traditional medicine to treat conditions such as abscesses, ulcers, and ear and eye infections. It is known to have a wide range of biological properties, such as antibacterial, antioxidant, antifungal, anti-inflammatory, anti-diabetic and anti-cancer effects. In this study, we established in vitro cultures from both the aerial parts and roots of Plectranthus scutellarioides. Subsequently, we compared the basic phytochemical profile of the obtained extracts and conducted a biological analysis to assess their potential for inducing apoptosis in breast (MCF-7) and lung (A549) cancer cells. Phytochemical analysis by HPLC-MS revealed the presence of compounds belonging to phenolic acids (ferulic, syringic, vanillic, rosmarinic, chlorogenic, caffeic, coumaric, dihydroxybenzoic acids), flavonoids (eriodyctiol and cirsimaritin), and terpenes such as 6,11,12,14,16-Pentahydroxy-3,17diacetyl-8,11,13-abietatrien-7-one, 6,11,12,14,16-Pentahydroxy-3,17-diacetyl5,8,11,13-abietatetraen-7-one, and 3,6,12-Trihydroxy-2-acetyl-8,12-abietadien7,11,14-trione. The results show that both extracts have a cytotoxic and genotoxic effect against MCF-7 and A549 cancer cells, with a different degree of sensitivity. It was also shown that both extracts can induce apoptosis by altering the expression of apoptotic genes (Bax, Bcl-2, TP53, Fas, and TNFSF10), reducing mitochondrial membrane potential, increasing ROS levels, and increasing DNA damage. In addition, it has been shown that the tested extracts can alter blood coagulation parameters. Our results indicate that extracts from in vitro cultures of Plectranthus scutellarioides aerial parts and roots have promising therapeutic application, but further research is needed to better understand the mechanisms of their action in the in vitro model.

Signal transducer and oxidative stress mediated modulation of phenylpropanoid pathway to enhance rosmarinic acid biosynthesis in fungi elicited whole plant culture of Solenostemon scutellarioides

This study aimed to improve rosmarinic acid (RA) production in the whole plant culture of Solenostemon scutellarioides through elicitation with phytopathogenic fungi. Amongst selected fungi, Aternaria alternata caused significant elevation (p<0.05-0.01) in RA accumulation (∼1.3-1.6-fold) between 25 and 100 μg l(-1). However, elicitation at the dose of 50 μg l(-1) has been found to be most effective and intracellular RA content reached almost ∼1.6-fold (p<0.01) higher in day 7. Therefore, A. alternata (50 μg l(-1)) was selected for mechanism evaluation. A significant elevation of intercellular jasmonic acid was observed up to day 6 after elicitation with A. alternata (50 μg l(-1)). A significant increase in tissue H2O2 and lipid peroxidation coupled with depletion of antioxidant enzymes superoxide dismutase and catalase indicated augmented oxidative stress associated with biotic interaction. Preceding the elicitor-induced RA accumulation, a notable alteration in the specific activities of biosynthetic enzymes namely PAL and TAT was recorded, while, no significant change in the activities of RAS was observed. HPPR activity was slightly improved in elicited plant. Therefore, it could be concluded that A. alternata elicited the biosynthesis of rosmarinic acid via signal transduction through jasmonic acid coupled with elicitor induced oxidative stress and associated mechanism.

Enhanced rosmarinic acid biosynthesis in Solenostemon scutellarioides culture: a precursor-feeding strategy

The aim of this study was to employ precursor-feeding strategy for the improved production of rosmarinic acid (RA) in Solenostemon scutellarioides in vitro. The cultures were fed with precursors, namely l-phenylalanine (Phe), l-tyrosine (Tyr) and cucumber juice (CJ), at different concentrations. Phe (100 mg L(-1)) and Tyr (400 mg L(-1)) caused ∼1.5- and 2.1-fold increase in RA accumulation within 48 h. CJ (50 mg L(-1)) feeding displayed highest RA content (∼1.6-fold) in 72 h. In this study, we focused on the function of individual precursor on key enzymes involved in RA biosynthesis. The phenylalanine ammonia lyase activity was significantly upregulated after Phe (100 mg L(-1)) feeding, while tyrosine aminotransferase and hydroxyphenylpyruvate reductase activities were improved with Tyr (400 mg L(-1)) treatment. However, rosmarinic acid synthase activity was significantly enhanced by all three precursors. In synergy study, Phe (100 mg L(-1)) + Tyr (400 mg L(-1)) could enhance (∼3.1-fold) RA biosynthesis within 48 h.

Bioproduction and Optimization of Rosmarinic Acid Production in Solenostemon Scutellarioides through Media Manipulation and Conservation of High Yielding Clone via Encapsulation

The present study describes the role of different exogenous phytohormones, polyamines and sucrose on growth and rosmarinic acid (RA) production in whole plant culture of Solenostemon scutellarioides. It was further aimed to conserve elite clones via synthetic seed technology. S. scutellarioides was treated either singly or in combination with different phytohormones. Cultures incubated with NAA (0.5 mg L−1) yielded the highest RA accumulation (g−1FW), but negatively affected the growth. So, overall RA content was insignificant. Cultures incubated with IBA, BAP and GA3 at low concentration significantly improved growth and RA bioaccumulation. In the combinatorial study, IBA+BAP+GA3 (0.5 mg L−1 each) was found optimum for plant biomass and RA production (65.2% improvement of total RA). Amongst polyamines, putrescine (1 mg L−1) exhibited 20.4% improvement of total RA content. The intracellular RA accumulation (g−1FW) was significantly higher between 5 and 7% of sucrose concentrations. However, the total increase in RA content was inhibited due to deterioration of the culture with increasing sucrose concentration. Based on the effect of different treatments on growth and RA accumulation, a high yielding and stable plant line was selected for conservation via alginate encapsulation. Uniform shaped alginate coated synthetic seeds conserved up to 6 months exhibited high regeneration potential and RA content.