Light elicited growth, antioxidant enzymes activities and production of medicinal compounds in callus culture of Cnidium officinale Makino

Manipulating the light spectrum to increase the biomass production, physiological plasticity and nutritional quality of Eruca sativa L

The extensive development in light-emitting diodes (LEDs) in recent years provides an opportunity to positively influence plant growth and biomass accumulation and to optimize biochemical composition and nutritional quality. This study aimed to assess how different light spectra affect the growth, photosynthesis and biochemical properties of Eruca sativa. Therefore two LED lighting modes - red:blue (RB, 1:1) and red:green:blue (RGB, 2:1:2) were compared to the conventional white light fluorescent tubes (WL). Plant biomass, photosynthetic performance, several antioxidants, polyamines and nitrates contents were analyzed across different treatments. The plant growth was affected by the light quality - the presence of green light in the spectrum resulted in smaller plants and leaves, and correspondingly less biomass. RB spectral mode enhanced the total antioxidant and guaiacol peroxidase activity, pigments, flavonoids, polyphenols, ascorbate and polyamines contents. This effect under RB was combined with better leaf development compared to RGB and less nitrate in the leaves among all treatments. The RB light generated modifications in polyamines, which are interrelated with the nitrate content, further induce important metabolite and antioxidant changes. Both RB and RGB enhanced photosynthesis. The afterglow thermoluminescence band varied according to leaves development, being higher in RB and WL as a consequence of their faster growth. The RB light spectrum was found to be the most efficient for promoting the growth, biochemical composition, and overall quality of Eruca sativa compared to RGB and WL. These findings suggest that RB LEDs can be an effective tool for improving crop production in controlled environments.

Influence of Primary Light Exposure on the Morphophysiological Characteristics and Phenolic Compounds Accumulation of a Tea Callus Culture (Camellia sinensis L.)

Tea plant calli (Camellia sinensis L.) are characterized by the accumulation of various phenolic compounds (PC)-substances with high antioxidant activity. However, there is still no clarity on the response of tea cells to light exposure of varying intensity. The purpose of the research was to study tea callus cultures grown under the influence of primary exposure to different light intensities (50, 75, and 100 µmol·m-2·s-1). The cultures' growth, morphology, content of malondialdehyde and photosynthetic pigments (chlorophyll a and b), accumulation of various PC, including phenylpropanoids and flavanols, and the composition of catechins were analyzed. Primary exposure to different light intensities led to the formation of chloroplasts in tea calli, which was more pronounced at 100 µmol·m-2·s-1. Significant similarity in the growth dynamics of cultures, accumulation of pigments, and content of malondialdehyde and various phenolics in tea calli grown at light intensities of 50 and 75 µmol·m-2·s-1 has been established, which is not typical for calli grown at 100 µmol·m-2·s-1. According to data collected using high-performance liquid chromatography, (+)-catechin, (-)-epicatechin, epigallocatechin, gallocatechin gallate, epicatechin gallate, and epigallocatechin gallate were the main components of the tea callus culture's phenolic complex. Its content changed under the influence of primary exposure to light, reaching the greatest accumulation in the final stages of growth, and depended on the light intensity. The data obtained indicate changes in the morphophysiological and biochemical characteristics of tea callus cultures, including the accumulation of PC and their individual representatives under primary exposure to light exposure of varying intensity, which is most pronounced at its highest values (100 µmol·m-2·s-1).

Biological, Antifungal, and Physical Efficacy of a Denture Cleanser Formulated with Cnidium officinale Extracts

BACKGROUND/OBJECTIVES

We aimed to assess the antifungal efficacy and impact of a denture cleanser containing Cnidium officinale extract on the surface characteristics of denture base materials, as well as its physical and biological properties.

METHODS

The experimental denture cleansers were formulated with C. officinale at concentrations of 100 and 150 μg/mL, combined with 1% cocamidopropyl betaine as a natural surfactant. Antifungal efficacy was evaluated using zone-of-inhibition assays against Candida albicans, revealing inhibition zones of 20 ± 1.8 mm for the 100 μg/mL concentration and 23.6 ± 1.6 mm for the 150 μg/mL concentration. Surface property assessments-including hardness, roughness, color stability, and solubility measurements-demonstrated no significant differences compared to the control group. Biological evaluations included the quantification of polyphenol and flavonoid content.

RESULTS

The C. officinale-based cleanser showed significant antifungal activity without affecting the hardness, roughness, color stability, or solubility of denture base materials. Biological tests revealed no cytotoxicity and minimal mucosal irritation. Polyphenol and flavonoid contents were quantitatively measured, revealing higher concentrations in the experimental groups, which were correlated with significant antifungal activity. These compounds are known for their roles in disrupting microbial processes and enhancing antimicrobial effects. These findings suggest that the C. officinale-based denture cleanser effectively inhibits C. albicans while preserving the physical properties of denture base materials.

CONCLUSIONS

This study highlights the potential of C. officinale in denture cleanser formulations, promoting denture hygiene and oral health. Future research should prioritize long-term clinical evaluations and formulation optimization.

Deciphering the virome of Chunkung (Cnidium officinale) showing dwarfism-like symptoms via a high-throughput sequencing analysis

BACKGROUND

Viruses have notable effects on agroecosystems, wherein they can adversely affect plant health and cause problems (e.g., increased biosecurity risks and economic losses). However, our knowledge of their diversity and interactions with specific host plants in ecosystems remains limited. To enhance our understanding of the roles that viruses play in agroecosystems, comprehensive analyses of the viromes of a wide range of plants are essential. High-throughput sequencing (HTS) techniques are useful for conducting impartial and unbiased investigations of plant viromes, ultimately forming a basis for generating further biological and ecological insights. This study was conducted to thoroughly characterize the viral community dynamics in individual plants.

RESULTS

An HTS-based virome analysis in conjunction with proximity sampling and a tripartite network analysis were performed to investigate the viral diversity in chunkung (Cnidium officinale) plants. We identified 61 distinct chunkung plant-associated viruses (27 DNA and 34 RNA viruses) from 21 known genera and 6 unclassified genera in 14 known viral families. Notably, 12 persistent viruses (7 DNA and 5 RNA viruses) were exclusive to dwarfed chunkung plants. The detection of viruses from the families Partitiviridae, Picobirnaviridae, and Spinareoviridae only in the dwarfed plants suggested that they may contribute to the observed dwarfism. The co-infection of chunkung by multiple viruses is indicative of a dynamic and interactive viral ecosystem with significant sequence variability and evidence of recombination.

CONCLUSIONS

We revealed the viral community involved in chunkung. Our findings suggest that chunkung serves as a significant reservoir for a variety of plant viruses. Moreover, the co-infection rate of individual plants was unexpectedly high. Future research will need to elucidate the mechanisms enabling several dozen viruses to co-exist in chunkung. Nevertheless, the important insights into the chunkung virome generated in this study may be relevant to developing effective plant viral disease management and control strategies.

Cnidium officinale Makino: Phytology, Phytochemistry, Toxicology, Pharmacology and Prescriptions (1967-2023)

Cnidium officinale Makino (COM), a perennial herbaceous plant in the Apiaceous family, widely distribute in Eastern Asia and Asia-Temperate. It has a long history application as a traditional medicine for invigorating the blood and removing blood stasis, and also has been employed to diet, pesticide, herbal bathing materials, the cosmetic and skin care industry. However, there has been no associated review of literature in the past half a century (1967-2023). By searching the international authoritative databases and collecting 229 literatures closely related to COM, herewith a comprehensive and systematic review was conducted. The phytology includes plant distribution and botanical characteristics. The phytochemistry covers 8 major categories, 208 compounds in total, and the quantitative determination of 14 monomer compounds, total polyphenols and total flavonoids. The clinical trial in pregnant women and toxic experiments in mice, the pharmacology of 7 aspects and 82 frequently used prescriptions are summarized. It is expected that this paper will provide forward-looking scientific thinking and literature support for the further modern research, development and utilization of COM.

Co-cultures from Plants and Cyanobacteria: A New Way for Production Systems in Agriculture and Bioprocess Engineering

Due to the global increase in the world population, it is not possible to ensure a sufficient food supply without additional nitrogen input into the soil. About 30-50% of agricultural yields are due to the use of chemical fertilizers in modern times. However, overfertilization threatens biodiversity, such as nitrogen-loving, fast-growing species overgrow others. The production of artificial fertilizers produces nitrogen oxides, which act as greenhouse gases. In addition, overfertilization of fields also releases ammonia, which damages surface waters through acidification and eutrophication. Diazotrophic cyanobacteria, which usually form a natural, stable biofilm, can fix nitrogen from the atmosphere and release it into the environment. Thus, they could provide an alternative to artificial fertilizers. In addition to this, biofilms stabilize soils and thus protect against soil erosion and desiccation. This chapter deals with the potential of cyanobacteria as the use of natural fertilizer is described. Possible partners such as plants and callus cells and the advantages of artificial co-cultivation will be discussed later. In addition, different cultivation systems for studying artificial co-cultures will be presented. Finally, the potential of artificial co-cultures in the agar industry will be discussed.

Phytomediated selenium nanoparticles and light regimes elicited in vitro callus cultures for biomass accumulation and secondary metabolite production in Caralluma tuberculata

Introduction

Caralluma tuberculata holds significant importance as a medicinal plant due to its abundance of bioactive metabolites, which offer a wide range of therapeutic potentials. However, the sustainable production of this plant is challenged by overexploitation, changes in natural conditions, slow growth rate, and inadequate biosynthesis of bioactive compounds in wild populations. Therefore, the current study was conducted to establish an in vitro based elicitation strategy (nano elicitors and light regimes) for the enhancement of biomass and production of secondary metabolites.

Methods

Garlic clove extract was employed as a stabilizing, reducing, or capping agent in the green formulation of Selenium nanoparticles (SeNPs) and various physicochemical characterization analyses such as UV visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-Ray (EDX) Spectroscopy, fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were performed. Furthermore, the effects of phytosynthesized SeNPs at various concentrations (0, 50, 100, 200, and 400 µg/L on callus proliferation and biosynthesis of medicinal metabolites under different light regimes were investigated.

Results and discussion

Cultures grown on Murashige and Skoog (MS) media containing SeNPs (100 µg/L), in a dark environment for two weeks, and then transferred into normal light, accumulated maximum fresh weight (4,750 mg/L FW), phenolic contents (TPC: 3.91 mg/g DW), flavonoid content (TFC: 2.04 mg/g DW) and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) antioxidant activity (85%). Maximum superoxide dismutase (SOD: 4.36 U/mg) and peroxide dismutase activity (POD: 3.85 U/mg) were determined in those cultures exposed to SeNPs (100 µg/L) under complete dark conditions. While the callus cultures proliferate on media augmented with SeNPs (200 µg/L) and kept under dark conditions for two weeks and then shifted to normal light conditions exhibited the highest catalase (CAT: 3.25 U/mg) and ascorbate peroxidase (APx: 1.93 U/mg) activities. Furthermore, LC-ESI-MS/MS analysis confirmed the effects of SeNPs and light conditions that elicited the antidiabetic metabolites (cumarins, gallic acid, caffeic acid, ferulic acid, catechin, querctin and rutin). This protocol can be scaled up for the industrial production of plant biomass and pharmacologically potent metabolites using in vitro callus cultures of C. tuberculata.

Biochemical and phytochemical responses of Ammi visnaga L. (Apiaceae) callus culture elicited by SiO2 and graphene Oxide-SiO2 nanoparticles

Ammi visnaga L. is an enriched medicinal plant with medicinally important compounds. Two types of nanoparticles (NPs) including silica (SiO₂) and graphene oxide bound with SiO₂ (GO-SiO₂) NPs at different concentrations (0, 15, 25 mg L^-1) were used as elicitors to investigate their effects on callus morphology, H₂O₂ content, total phenolic content (TPC), total flavonoids content (TFC), ferric reducing/antioxidant power (FRAP), and few antioxidant enzymes such as catalase (CAT), guaiacol peroxidase (GPX), superoxide dismutase (SOD), ascorbate peroxidase (APX), and polyphenol oxidase (PPO) in the callus cultures of A. visnaga. The effects of elicitation of both NPs on calli were observed using a scanning electron microscope (SEM). The 15 mg L^-1 concentration of GO-SiO₂ NPs produced the highest TPC (193.3 mg GAE g^-1 FW), CAT (13.1 U mg^-1 Protein), GPX (0.0089 U mg^-1 Protein), and APX (0.079 U mg^-1 Protein). Whereas, the maximum content of H₂O₂ (0.68 μmol g^-1 FW), FRAP (0.0092 μmol mg^-1), and TFC (62.27 mg QE g^-1 FW) was observed at 25 mg L^-1 and 15 mg L^-1 of SiO₂ NPs, respectively. Conclusively, in the callus culture of A. visnaga, the 15 mg L^-1 concentration of GO-SiO₂ NPs was the most suitable dosage for enhancing the enzymatic antioxidant activities (CAT, GPX, APX) and TPC, rather than SiO₂ NPs.

Blue LED light promoting the growth, accumulation of high-value isoflavonoids and astragalosides, antioxidant response, and biosynthesis gene expression in Astragalus membranaceus (Fisch.) Bunge hairy root cultures

The root of Astragalus membranaceus (Fisch.) Bunge is one of the most frequently used herbs in traditional Chinese medicine (TCM) formulae for fighting COVID-19 infections, due to the presence of isoflavonoids and astragalosides associated with antiviral and immune-enhancing activities. For the first time, the exposure of A. membranaceus hairy root cultures (AMHRCs) to different colors of LED lights i.e., red, green, blue, red/green/blue (1/1/1, RGB), and white, was conducted to promote the root growth and accumulation of isoflavonoids and astragalosides. LED light treatment regardless of colors was found beneficial for root growth, which might be a result of the formation of more root hairs upon light stimulation. Blue LED light was found most effective for enhancing phytochemical accumulation. Results showed that the productivity of root biomass in blue-light grown AMHRCs with an initial inoculum size of 0.6% for 55 days was 1.40-fold higher than that in dark (control), and yields of high-value isoflavonoids and astragalosides including calycosin, formononetin, astragaloside IV, and astragaloside I increased by 3.17-fold, 2.66-fold, 1.78-fold, and 1.52-fold relative to control, respectively. Moreover, the photooxidative stress together with transcriptional activation of biosynthesis genes might contribute to the enhanced accumulation of isoflavonoids and astragalosides in blue-light grown AMHRCs. Overall, this work offered a feasible approach for obtaining higher yields of root biomass and medicinally important compounds in AMHRCs via the simple supplementation of blue LED light, which made blue-light grown AMHRCs industrially attractive as plant factory in controlled growing systems.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11240-023-02486-7.

Influence of Plant Growth Regulators and Artificial Light on the Growth and Accumulation of Inulin of Dedifferentiated Chicory (Cichorium intybus L.) Callus Cells

Chicory (Chicorium intybus L.) is a perennial herb of the family Asteraceae, widely distributed in Asia and Europe, commonly used industrially as a raw material for extracting inulin because of a high content of inulin and biologically active compounds. Light conditions and plant growth regulators (PGRs) are two of many factors that affect the growth and inulin content of chicory callus. The aim of this work is to study the effect of PGRs and light conditions on proliferation and accumulation of inulin of chicory callus in vitro. In this study, we used semi-solid MS medium supplemented with different auxins (including Indole-3-acetic acid (IAA), naphthylacetic acid (NAA), and 2,4-dichlorophenoxyacetic acid (2,4-D)) at a concentration of 5.5−9.5 mg/L in combination with 2.0 mg/L 6 benzylaminopurine (BA) to determine induction and proliferation of callus. The increasing value of callus fresh weight was used to assess the growth of the callus in treatments. The results showed that a steady increase in callus fresh weight and inulin content in callus cells was obtained when they were cultured on MS medium supplemented with a combination of 2.0 mg/L BA with 7.5 mg/L IAA in lighting conditions with radiation equalized by the flux density of photosynthetic photons and ratios of radiation levels in the region of FR—far red > R—red. Increasing demand for organic inulin sources in production practice can be met by our finding.

Anti-Oxidant and Anti-Aging Activities of Callus Culture from Three Rice Varieties

The aims of this study were to induce calli from the seeds of three rice varieties (Hommali 105, Munpu, and Niawdum) and investigate their anti-aging potential. First, rice seeds were cultured on a Murashige and Skoog medium (MS medium) supplemented with 2 mg/L of 2,4-Dichlorophenoxyacetic acid (2,4-D), 1 mg/L of 1-Naphthalene acetic acid (NAA), and 1 mg/L of 6-Benzylaminopurine (BAP). After three weeks, the calli were extracted with ethanol. Then, their phenolic contents were determined by spectrophotometer and the amino acids were identified by ultra-performance liquid chromatography (UPLC). Their cytotoxicity, anti-oxidant (potassium ferricyanide reducing power assay (PFRAP), DPPH radical scavenging assay (DPPH), lipid peroxidation inhibition (LPO), and superoxide dismutase activity (SOD)), and anti-aging (keratinocyte proliferation, anti-collagenase, anti-inflammation, and anti-tyrosinase) activities were also investigated. Munpu callus (385%) was obtained with a higher yield than Hommali (322%) and Niawdum (297%) calli. The results revealed that the phenolic and amino acid contents were enhanced in the calli. Moreover, the calli were rich in glutamic acid, alanine, and gamma aminobutyric acid (GABA). The callus extracts showed no cytotoxic effects at a concentration of equal to or lower than 0.25 mg/mL. The highest anti-oxidant activities (PFRAP (0.81 mg AAE/mL), DPPH (68.22%), LPO (52.21%), and SOD (67.16%)) was found in Munpu callus extract. This extract also had the highest keratinocyte proliferation (43.32%), anti-collagenase (53.83%), anti-inflammation (85.40%), and anti-tyrosinase (64.77%) activities. The experimental results suggest that the amounts of bioactive compounds and anti-aging activities of rice seeds can be enhanced by the induction of callus formation.

Low-cost alternative for the bioproduction of bioactive phenolic compounds of callus cultures from Cereus hildmannianus (K.) Schum

The aim of this study was to establish a sustainable alternative callus culture of Cereus hildmannianus for the production and bioactive determination of phenolic compounds from this species. The conventional callus was cultivated using agar and Murashige and Skoog (MS) medium, while for the alternative culture the agar was replaced with a cotton support covered with filter paper and MS medium (incubated at 32°C with photoperiod of 16h), and the morphological characteristics and growth index were assessed (8 weeks). Extracts were obtained by maceration followed by partition, characterized by nuclear magnetic resonance - NMR and ultra-high performance liquid chromatography - UHPLC, quantified (phenolic compounds) by UV-Vis methods, and their antioxidant, antitumor activities, as well as cytotoxicity, were evaluated. The establishment of an alternative callus culture was carried out successfully. Characteristic signals of phenolic compounds were determined by NMR, and 46 compounds with fragment ions were identified using UHPLC analysis. The highest concentrations of phenolic compounds, and greatest antioxidant and antitumor activities, were obtained with the dichloromethane fractions of both callus tissue cultures, which were not cytotoxic. The callus culture from C. hildmannianus has shown promise as a source for the sustainable production of phenolic compounds with antioxidant and antiproliferative activities and thus, has potential use as a natural antitumor product.

Effects of Light Spectra on Morphology, Gaseous Exchange, and Antioxidant Capacity of Industrial Hemp

One of the most important growth factors in cannabis cultivation is light which plays a big role in its successful growth. However, understanding that how light controls the industrial hemp growth and development is poor and needs advanced research. Therefore, a pot study was conducted to investigate the effects of different colors of light, that is, white light (WL), blue light (BL), red light (RL), and 50% red with 50% blue mix light (RBL) on morphology, gaseous exchange and antioxidant capacity of industrial hemp. Compared with WL, BL significantly increase hemp growth in terms of shoot fresh biomass (15.1%), shoot dry biomass (27.0%), number of leaves per plant (13.7%), stem diameter (10.2%), root length (6.8%) and chlorophyll content (7.4%). In addition, BL promoted net photosynthesis, stomatal conductance, and transpiration, while reduces the lipid peroxidation and superoxide dismutase and peroxidase activities. However, RL and RBL significantly reduced the plant biomass, gas exchange parameters with enhanced antioxidant enzymes activities. Thus, blue light is useful for large-scale sustainable production of industrial hemp.

Enhanced Accumulation of Biologically Active Coumarin and Furanocoumarins in Callus Culture and Field-grown Plants of Ruta chalepensis Through LED Light-treatment

Ruta chalepensis, a medicinal plant, produces biologically active coumarins (CRs) and furanocoumarins (FCRs). However, their yield is quite low in cultivated plants. In this work, the influence of light emitting diodes (LEDs) was investigated on the accumulation of CRs and FCRs in the callus cultures and field-grown plants of R. chalepensis. Among the various tested wavelengths of LED lights, maximum accumulation of CR and FCRs was recorded under blue LED treatment in both the callus cultures as well as field-grown plants as compared to respective controls treated with white LED. Metabolite analyses of LED-treated field-grown plants showed that highest concentrations of CR (umbelliferone, 2.8-fold), and FCRs (psoralen, 2.3-fold; xanthotoxin, 3.8-fold; bergapten, 1.16-fold) were accumulated upon blue LED-treatment for six days. CR and FCRs contents were also analyzed in the blue- and red-LED-treated in vitro callus tissue. Upon blue LED-treatment, callus accumulated significantly high levels of umbelliferone (48.6 ± 1.2 µg/g DW), psoralen (370.12 ± 10.6 µg/g DW) and xanthotoxin (10.16 ± 0.48 µg/g DW). These findings imply that blue LED-treatment is a viable option as a non-invasive and low-cost elicitation technology for the enhanced production of biologically active CR and FCRs in field-grown plants and callus cultures of R. chalepensis.

Interactive effects of zinc oxide nano particles and different light regimes on growth and silymarin biosynthesis in callus cultures of Silybum marianum L

Silybum marianum L. commonly known as milk thistle is a medicinally potent plant with a multitude of pharmacological applications. The present investigations demonstrated the effects of Zinc Oxide nanoparticles (ZnO NPs) on callus growth and biosynthesis of silymarin in milk thistle under various light conditions. The callus cultures developed on Murashige and Skoog (MS) basal media containing ZnO NPs (0.15 mg/L), under the dark condition maintained for two weeks, followed by transference into normal light produced the maximum callus fresh weight (2294 mg/L FW). Further, the metabolite profiling revealed that ZnO NPs significantly augmented the production of silymarin and upregulated the antioxidant system in the callus cultures. Maximum TPC (total phenolic content: 37 ± 0.20 mg/g DW), TFC (total flavonoid content: 8.9 ± 0.023), DPPH antioxidant activity (91.5 ± 1.75%), Superoxide dismutase activity (SOD: 4.1 ± 0.045 nM/min/mg FW) and the highest silymarin content (14.6 ± 0.023 mg/g DW) were recorded in the callus cultures developed on MS media supplemented with solitary ZnO NPs (0.15 mg/L). While the callus culture evolved in presence of only PGRs (2,4 D and BA: 2 mg/L, each) accumulated the lesser fresh weight (562 mg/L FW). A higher concentration of ZnO NPs (0.15 mg/L) enhanced the secondary metabolite accumulation and silymarin content in the callus of Silybum marianum. This is the first standardized protocol to be applied on the industrial level for the production of silymarin.

Comparative Effects of Different Light Sources on the Production of Key Secondary Metabolites in Plants In Vitro Cultures

Plant secondary metabolites are known to have a variety of biological activities beneficial to human health. They are becoming more popular as a result of their unique features and account for a major portion of the pharmacological industry. However, obtaining secondary metabolites directly from wild plants has substantial drawbacks, such as taking a long time, posing a risk of species extinction owing to over-exploitation, and producing a limited quantity. Thus, there is a paradigm shift towards the employment of plant tissue culture techniques for the production of key secondary metabolites in vitro. Elicitation appears to be a viable method for increasing phytochemical content and improving the quality of medicinal plants and fruits and vegetables. In vitro culture elicitation activates the plant's defense response and increases the synthesis of secondary metabolites in larger proportions, which are helpful for therapeutic purposes. In this respect, light has emerged as a unique and efficient elicitor for enhancing the in vitro production of pharmacologically important secondary metabolites. Various types of light (UV, fluorescent, and LEDs) have been found as elicitors of secondary metabolites, which are described in this review.

Application of Light-Emitting Diodes for Improving the Nutritional Quality and Bioactive Compound Levels of Some Crops and Medicinal Plants

Light is a key factor that affects phytochemical synthesis and accumulation in plants. Due to limitations of the environment or cultivated land, there is an urgent need to develop indoor cultivation systems to obtain higher yields with increased phytochemical concentrations using convenient light sources. Light-emitting diodes (LEDs) have several advantages, including consumption of lesser power, longer half-life, higher efficacy, and wider variation in the spectral wavelength than traditional light sources; therefore, these devices are preferred for in vitro culture and indoor plant growth. Moreover, LED irradiation of seedlings enhances plant biomass, nutrient and secondary metabolite levels, and antioxidant properties. Specifically, red and blue LED irradiation exerts strong effects on photosynthesis, stomatal functioning, phototropism, photomorphogenesis, and photosynthetic pigment levels. Additionally, ex vitro plantlet development and acclimatization can be enhanced by regulating the spectral properties of LEDs. Applying an appropriate LED spectral wavelength significantly increases antioxidant enzyme activity in plants, thereby enhancing the cell defense system and providing protection from oxidative damage. Since different plant species respond differently to lighting in the cultivation environment, it is necessary to evaluate specific wavebands before large-scale LED application for controlled in vitro plant growth. This review focuses on the most recent advances and applications of LEDs for in vitro culture organogenesis. The mechanisms underlying the production of different phytochemicals, including phenolics, flavonoids, carotenoids, anthocyanins, and antioxidant enzymes, have also been discussed.

Surface Characterization, Biocompatibility and Antifungal Efficacy of a Denture-Lining Material Containing Cnidium officinale Extracts

Herein, we investigated the surface characterization and biocompatibility of a denture-lining material containing Cnidium officinale extracts and its antifungal efficacy against Candida albicans. To achieve this, a denture-lining material containing various concentrations of C. officinale extract and a control group without C. officinale extract were prepared. The surface characterization and biocompatibility of the samples were investigated. In addition, the antifungal efficacy of the samples on C. albicans was investigated using spectrophotometric growth and a LIVE/DEAD assay. The results revealed that there was no significant difference between the biocompatibility of the experimental and control groups (p > 0.05). However, there was a significant difference between the antifungal efficiency of the denture material on C. albicans and that of the control group (p < 0.05), which was confirmed by the LIVE/DEAD assay. These results indicate the promising potential of the C. officinale extract-containing denture-lining material as an antifungal dental material.

Induction, Multiplication, and Evaluation of Antioxidant Activity of Polyalthia bullata Callus, a Woody Medicinal Plant

Polyalthia bullata is an endangered medicinal plant species. Hence, establishment of P. bullata callus culture is hoped to assist in mass production of secondary metabolites. Leaf and midrib were explants for callus induction. Both of them were cultured on Murashige and Skoog (MS) and Woody Plant Medium (WPM) containing different types and concentrations of auxins (2,4-dichlorophenoxyacetic acid (2,4-D), α-naphthaleneacetic acid (NAA), picloram, and dicamba). The callus produced was further multiplied on MS and WPM supplemented with different concentrations of 2,4-D, NAA, picloram, dicamba, indole-3-acetic acid (IAA), and indole-3-butyric acid (IBA) media. The quantification of total phenolic content (TPC), total flavonoid content (TFC) and antioxidant capacity was further carried out on P. bullata callus, and the results were subjected to correlation analysis. Among the media, the WPM + 16.56 µM picloram (53.33 ± 22.06%) was the best for callus induction while MS + 30 µM dicamba was the best for callus multiplication. The TPC, TFC, and EC₅₀ of DPPH scavenging activity were determined at 0.657 ± 0.07 mg GAE/g FW, 0.491 ± 0.03 mg QE/g, and 85.59 ± 6.09 µg/mL in P. bullata callus, respectively. The positive correlation between DPPH scavenging activity with TPC was determined at r = 0.869, and that of TFC was at r = 0.904. Hence, the P. bullata callus has an ability to accumulate antioxidants. It therefore can be a medium for secondary metabolites production.

Indirect somatic embryogenesis of purple coneflower (Echinacea purpurea (L.) Moench): a medicinal-ornamental plant: evaluation of antioxidant enzymes activity and histological study

Purple coneflower (Echinacea purpurea (L.) Moench) is a widely used medicinal and ornamental plant. In the present study, the callus embryogenesis was examined using benzyl adenine (BA) at three levels (3, 4, 5 mg L⁻¹), 1-Naphthalene acetic acid (NAA) at three levels (0.1, 0.2 and 0.5 mg L⁻¹) with or without activated charcoal (1 g L⁻¹), coconut milk (50 ml L⁻¹) and casein hydrolysate (50 mg L⁻¹) in the MS (Murashige and Skoog 1962) medium. The embryogenesis indirectly occurred with the production of callus. The calli were observed in three forms: undifferentiated, embryogenic and organogenic. The embryogenic calli were dark green and coherent with a faster growth rate. The highest embryogenesis (100%) and embryonic regeneration (plantlet production) were obtained in the combined BA + NAA treatments with the activated charcoal, coconut milk and casein hydrolysate. However, the combined treatments of growth regulators failed to produce somatic embryos without the use of coconut milk and casein hydrolysate. The maximum amount of protein, peroxidase and catalase activity of embryogenic calli (2.02, 1.79 and 6.62ΔOD/Min/mg.protein, respectively), and highest percentage of acclimatization success (29.3% of plants) were obtained in the combined treatment of 5 mg L⁻¹ BA + 0.5 mg L⁻¹ NAA + activated charcoal + coconut milk + casein hydrolysate. The highest amount of chlorophyll content (33.3 SPAD value) and growth characteristics of acclimatized plantlets were observed in the media containing 3 mg L⁻¹ BA + 0.1 and 0.2 mg L⁻¹ NAA + 1 g. L⁻¹ combined activated charcoal, coconut milk, casein hydrolysate. The histological studies confirmed the somatic embryogenesis in purple coneflower. Generally, it was found that the somatic embryogenesis of E. purpurea occurs at high levels of BA and low levels of NAA with the addition of coconut milk and casein hydrolysate.

Growth Kinetics, Metabolites Production and Expression Profiling of Picrosides Biosynthetic Pathway Genes in Friable Callus Culture of Picrorhiza kurroa Royle ex Benth

The rising demand for picrosides commercially and over-exploitation of Picrorhiza kurroa from natural habitat has to initiate alternative strategies for sustainable production of metabolites. In the present research, wild leaf explant of P. kurroa was used to produce friable callus under different culture condition, i.e., dark and light with two temperature variants (15 °C and 25 °C). Afterward, callus cell lines were screened based on growth biomass and metabolites content accumulation. The results revealed, maximum callus growth index along with antioxidant potential (IC₅₀-40.88 μg/mL) and total phenol content (41.35 μg/mg) were observed under dark 25 °C. However, under light 15 °C, highest accumulation of picroside II (0.58 μg/mg), cinnamic acid (0.15 μg/mg), p-hydroxy acetophenone (0.30 μg/mg), total flavonoids (77.30 μg/mg), nitrogen (7.06%), carbohydrates (18.03%), and protein (44.12%) were detected. Major reported metabolite in callus was picroside I (1.63 μg/mg) under dark 15 °C. For the first time, picroside III content (range 0.15-0.56 μg/mg) was also detected and quantified in leaf-derived calli. Expression profiling of picroside biosynthetic pathway genes showed a positive correlation with the observed metabolites. Furthermore, an optimized protocol of metabolites enriched callus biomass could be used as potential strategy for sustainable production of picrosides at commercial scale.

Influence of photoperiod on growth, bioactive compounds and antioxidant activity in callus cultures of Basella rubra L

Basella rubra L. is an important green leafy vegetable vine and is known for its health benefits in traditional medicine. Light is a basic physical factor essential to the development and bioactive secondary metabolite production in in vitro callus cultures. The present study researched the impact of different photoperiods on biomass, bioactive compounds, and antioxidant activity in callus cultures of B. rubra. The in vitro seedling based cotyledonary leaf explants responded differently, when cultured on Murashige and Skoog (MS) medium with varying concentrations and combination of auxins and cytokinins. The best callus proliferation was found in MS medium with 0.1 mg.L^-1 1-naphthaleneacetic acid (NAA) and 6 mg.L^-1 6-benzylaminopurine (BAP), with greenish callus inception by about 2 weeks. The growth curve recorded for 6 weeks of culturing revealed that the photoperiod effect was found to be pivotal for acquiring biomass. At the fifth week, the continuous light supported maximum biomass (12.42 g) production followed by the 16:8 h photoperiod (9.02 g) and continuous darkness (4.28 g). The 80% ethanol extract of 1-week-old callus that grows under the 16:8 h photoperiod showed the highest total phenolic content (TPC) (74 mg.100 g^-1 fresh weight, FW) when compared to all other extracts at different stages. The ferric reducing antioxidant power assay showed the highest (336.23 mg.100 g^-1 FW) activity in methanol extractions of first-week callus cultures maintained in the continuous light condition. HPLC-UV identification and quantification of individual phenolics and flavonoids, such as gallic, trans-cinnamic, quercetin, protocatechuic and rutin, were highest in the callus cultures. The outcome of this study is significant to this plant, as B. rubra is familiar for its important health constituents with high-value bioactives and applications in the pharma and nutraceutical industries.

Lights triggered differential accumulation of antioxidant and antidiabetic secondary metabolites in callus culture of Eclipta alba L

Eclipta alba L., also known as false daisy, is well known and commercially attractive plant with excellent hepatotoxic and antidiabetic activities. Light is considered a key modulator in plant morphogenesis and survival by regulating important physiological cascades. Current study was carried out to investigate growth and developmental aspects of E. alba under differential effect of multispectral lights. In vitro derived callus culture of E. alba was exposed to multispectral monochromatic lights under controlled aseptic conditions. Maximum dry weight was recorded in culture grown under red light (11.2 g/L) whereas negative effect was observed under exposure of yellow light on callus growth (4.87 g/L). Furthermore, red light significantly enhanced phenolics and flavonoids content (TPC: 57.8 mg/g, TFC: 11.1 mg/g) in callus cultures compared to rest of lights. HPLC analysis further confirmed highest accumulation of four major compounds i.e. coumarin (1.26 mg/g), eclalbatin (5.00 mg/g), wedelolactone (32.54 mg/g) and demethylwedelolactone (23.67 mg/g) and two minor compounds (β-amyrin: 0.38 mg/g, luteolin: 0.39 mg/g) in red light treated culture whereas stigmasterol was found optimum (0.22 mg/g) under blue light. In vitro based biological activities including antioxidant, antidiabetic and lipase inhibitory assays showed optimum values in cultures exposed to red light, suggesting crucial role of these phytochemicals in the enhancement of the therapeutic potential of E. alba. These results clearly revealed that the use of multispectral lights in in vitro cultures could be an effective strategy for enhanced production of phytochemicals.

Physiological and Proteomic Insights Into Red and Blue Light-Mediated Enhancement of in vitro Growth in Scrophularia kakudensis-A Potential Medicinal Plant

The current study has determined the effect of red and blue lights on the enhancement of growth, antioxidant property, phytochemical contents, and expression of proteins in Scrophularia kakudensis. In vitro-grown shoot tip explants of S. kakudensis were cultured on the plant growth regulator-free Murashige and Skoog (MS) medium and cultured under the conventional cool white fluorescent lamp (control), blue light-emitting diodes (LED) light, or red LED light. After 4 weeks, growth, stomatal ultrastructure, total phenols and flavonoids, activities of antioxidant enzymes, and protein expressions were determined. Interestingly, blue or red LED treatment increased the shoot length, shoot diameter, root length, and biomass on comparison with the control. In addition, the LED treatments enhanced the contents of phytochemicals in the extracts. The red LED treatment significantly elicited the accumulation of flavonoids in comparison with the control. In accordance with the secondary metabolites, the LED treatments modulated the activities of antioxidant enzymes. Moreover, the proteomic insights using two-dimensional gel electrophoresis system revealed the proteins involved in transcription and translation, carbohydrate mechanism, post-translational modification, and stress responses. Taken together, the incorporation of blue or red LED during in vitro propagation of S. kakudensis can be a beneficial way to increase the plant quality and medicinal values of S. kakudensis.

Red light controlled callus morphogenetic patterns and secondary metabolites production in Withania somnifera L

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Combination of thidiazuron and naphthalene acetic acid induced callus growth in Withania somnifera.

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Red light improved callus growth with lower antioxidant enzymes activities.

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Violet light enhanced the total phenolic and flavonoid content in callus culture of W. somnifera.

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Withaferin A and chlorogenic acid were detected in callus cultures.

Withania somnifera L. is an endangered medicinal plant of higher market value. The in vitro callus cultures were established on Murashige and Skoog (MS) media augmented with different plant growth regulators. The MS medium containing 0.5 mg∙L⁻¹ of each TDZ and NAA was found to be optimal for callus formation and growth. Further, callus cultures were raised in different light wavelengths to find the right wavelength carrying the photons for the ideal cell growth of W. somnifera. Among the different wavelengths, red light was best for maximum biomass accumulation in callus culture. However, violet light condition was proven to be favouring the phenols and flavonoids synthesis in the callus cultures. Compared to other wavelengths, red light grown callus extract showed significantly higher content of chlorogenic acid, and withaferin A. This study concludes that red light treatment was optimum for maximum biomass accumulation and anti-oxidant activity in calli of W. somnifera.