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Graphical demonstartion of the Manikara zapota-mediated biosynthesis of Bimetallic nanoparticles (BNPs) and evalution of their biological activities.

International audience; Melatonin, a multifunctional signaling molecule, is ubiquitously distributed in different parts of a plant and responsible for stimulating several physiochemical responses against adverse environmental conditions in various plant systems. Melatonin acts as an indoleamine neurotransmitter and is primarily considered as an antioxidant agent that can control reactive oxygen and nitrogen species in plants. Melatonin, being a signaling agent, induces several specific physiological responses in plants that might serve to enhance photosynthesis, growth, carbon fixation, rooting, seed germination and defense against several biotic and abiotic stressors. It also works as an important modulator of gene expression related to plant hormones such as in the metabolism of indole-3-acetic acid, cytokinin, ethylene, gibberellin and auxin carrier proteins. Additionally, the regulation of stress-specific genes and the activation of pathogenesis-related protein and antioxidant enzyme genes under stress conditions make it a more versatile molecule. Because of the diversity of action of melatonin, its role in plant growth, development, behavior and regulation of gene expression it is a plant's master regulator. This review outlines the main functions of melatonin in the physiology, growth, development and regulation of higher plants. Its role as anti-stressor agent against various abiotic stressors, such as drought, salinity, temperatures, UV radiation and toxic chemicals, is also analyzed critically. Additionally, we have also identified many new aspects where melatonin may have possible roles in plants, for example, its function in improving the storage life and quality of fruits and vegetables, which can be useful in enhancing the environmentally friendly crop production and ensuring food safety.

The green synthesis of nanoparticles has emerged as a simple, safe, sustainable, reliable and eco-friendly protocol. Among different types of NPs, green-synthesized zinc oxide NPs (ZnONPs) show various promising biological uses due to their interesting magnetic, electrical, optical and chemical characteristics. Keeping in view the dependence of the therapeutic efficacy of NPs on their physico-chemical characteristics, the green synthesis of ZnONPs using Casuarina equisetifolia leaf extract under UV-A and UV-C light was carried out in this study. UV-irradiation helped to control the size and morphology of ZnONPs by exciting the electrons in the photoactive compounds of plant extracts to enhance the bio-reduction of ZnO into ZnONPs. C. equisetifolia leaf extract was found enriched with phenolic (2.47 ± 0.12 mg GAE/g DW) and flavonoid content (0.88 ± 0.28 mg QE/g DW) contributing to its 74.33% free-radical scavenging activity. FTIR spectra showed the involvement of polyphenols in the bio-reduction, stabilization and capping of ZnONPs. Moreover, SEM-EDX and XRD analyses showed great potential of UV-C light in yielding smaller (34–39 nm) oval-shaped ZnONPs, whereas UV-A irradiation resulted in the formation of fairly spherical 67–71 nm ZnONPs and control ZnONPs were of mixed shape and even larger size (84–89 nm). Green-synthesized ZnONPs, notably CE-UV-C-ZnONPs, showed promising anti-bacterial activities against Bacillus subtilis, Pseudomonas fluorescens and Pseudomonas aeruginosa. Moreover, ZnONPs also enhanced ROS production which led to a significant loss of mitochondrial membrane potential and activated caspase-3 gene expression and caspase-3/7 activity in human hepatocellular carcinoma (HepG2) cells. CE-UV-C-ZnONP treatment reduced HepG2 cell viability to as low as 36.97% owing to their unique shape and smaller size. Lastly, ZnONPs were found to be highly biocompatible towards brine shrimp and human red blood cells suggesting their bio-safe nature. This research study sheds light on the plausible role of UV radiation in the green synthesis of ZnONPs with reasonable control over their size and morphology, thus improving their biological efficacy.

A nano-revolution based on the green synthesis of nanomaterials could affect all areas of human life, and nanotechnology represents a propitious platform for various biomedical applications. During the synthesis of nanoparticles, various factors can control their physiognomies and clinical activities. Light is one of the major physical factors that can play an important role in tuning/refining the properties of nanoparticles. In this study, biocompatible monometallic (AgNPs and ZnONPs) and bimetallic Ag–ZnONPs (0.1/0.1 and 0.1/0.5) were synthesized under UV-C light irradiation from the leaf extract of Morus macroura, which possesses enriched TPC (4.238 ± 0.26 mg GAE/g DW) and TFC (1.073 ± 0.18 mg QE/g DW), as well as strong FRSA (82.39%). These green synthesized NPs were evaluated for their anti-diabetic, anti-glycation, and biocompatibility activities. Furthermore, their anti-cancerous activity against HepG2 cell lines was assessed in terms of cell viability, production of reactive oxygen/nitrogen species, mitochondrial membrane potential, and apoptotic caspase-3/7 expression and activity. Synthesized NPs were characterized by techniques including ultraviolet-visible spectroscopy, SEM, EDX, FTIR, and XRD. UV-C mediated monometallic and bimetallic NPs showed well-defined characteristic shapes with a more disperse particle distribution, definite crystalline structures, and reduced sizes as compared to their respective controls. In the case of clinical activities, the highest anti-diabetic activity (67.77 ± 3.29% against α-amylase and 35.83 ± 2.40% against α-glucosidase) and anti-glycation activity (37.68 ± 3.34% against pentosidine-like AGEs and 67.87 ± 2.99% against vesperlysine-like AGEs) was shown by UV-C mediated AgNPs. The highest biocompatibility (IC50 = 14.23 ± 1.68 µg/mL against brine shrimp and 2.48 ± 0.32% hemolysis of human red blood cells) was shown by UV-C mediated ZnONPs. In the case of anti-cancerous activities, the lowest viability (23.45 ± 1.40%) with enhanced ROS/NOS production led to a significant disruption of mitochondrial membrane potential and greater caspase-3/7 gene expression and activity by UV-C mediated bimetallic Ag–ZnONPs (0.1/0.5). The present work highlights the positive effects of UV-C light on physico-chemical physiognomies as well as the clinical activities of NPs.

A nano-revolution based on the green synthesis of nanomaterials could affect all areas of human life, and nanotechnology represents a propitious platform for various biomedical applications. During the synthesis of nanoparticles, various factors can control their physiognomies and clinical activities. Light is one of the major physical factors that can play an important role in tuning/refining the properties of nanoparticles. In this study, biocompatible monometallic (AgNPs and ZnONPs) and bimetallic Ag–ZnONPs (0.1/0.1 and 0.1/0.5) were synthesized under UV-C light irradiation from the leaf extract of Morus macroura, which possesses enriched TPC (4.238 ± 0.26 mg GAE/g DW) and TFC (1.073 ± 0.18 mg QE/g DW), as well as strong FRSA (82.39%). These green synthesized NPs were evaluated for their anti-diabetic, anti-glycation, and biocompatibility activities. Furthermore, their anti-cancerous activity against HepG2 cell lines was assessed in terms of cell viability, production of reactive oxygen/nitrogen species, mitochondrial membrane potential, and apoptotic caspase-3/7 expression and activity. Synthesized NPs were characterized by techniques including ultraviolet-visible spectroscopy, SEM, EDX, FTIR, and XRD. UV-C mediated monometallic and bimetallic NPs showed well-defined characteristic shapes with a more disperse particle distribution, definite crystalline structures, and reduced sizes as compared to their respective controls. In the case of clinical activities, the highest anti-diabetic activity (67.77 ± 3.29% against α-amylase and 35.83 ± 2.40% against α-glucosidase) and anti-glycation activity (37.68 ± 3.34% against pentosidine-like AGEs and 67.87 ± 2.99% against vesperlysine-like AGEs) was shown by UV-C mediated AgNPs. The highest biocompatibility (IC50 = 14.23 ± 1.68 µg/mL against brine shrimp and 2.48 ± 0.32% hemolysis of human red blood cells) was shown by UV-C mediated ZnONPs. In the case of anti-cancerous activities, the lowest viability (23.45 ± 1.40%) with enhanced ROS/NOS production led to a significant disruption of mitochondrial membrane potential and greater caspase-3/7 gene expression and activity by UV-C mediated bimetallic Ag–ZnONPs (0.1/0.5). The present work highlights the positive effects of UV-C light on physico-chemical physiognomies as well as the clinical activities of NPs.

Simple Summary Despite breakthroughs in medicine, cancer remains one of the most feared diseases. Traditionally, chemotherapies have been the treatment of choice. However, concerns about stability and poor solubility prevent them from being widely used. Destruction of healthy cells, hair loss, and drug resistance are all common side effects. In this aspect, nanotechnology opens up new avenues for cancer treatment. ZnO NPs are one of the most valuable metal oxide nanoparticles in cancer treatment owing to their high biocompatibility and low toxicity. The ability of ZnO NPs to selectively trigger the formation of reactive oxygen species and induce apoptosis has been critically appraised in this review. They are also the best contenders for diagnosis and tailored drug delivery in cancer therapeutics. Here, we extensively summarize the role of ZnO NPs in cancer diagnosis, target drug delivery, and treatment, which will help in future research advancements in the field of cancer theranostic. Abstract Cancer is regarded as one of the most deadly and mirthless diseases and it develops due to the uncontrolled proliferation of cells. To date, varieties of traditional medications and chemotherapies have been utilized to fight tumors. However, their immense drawbacks, such as reduced bioavailability, insufficient supply, and significant adverse effects, make their use limited. Nanotechnology has evolved rapidly in recent years and offers a wide spectrum of applications in the healthcare sectors. Nanoscale materials offer strong potential for curing cancer as they pose low risk and fewer complications. Several metal oxide NPs are being developed to diagnose or treat malignancies, but zinc oxide nanoparticles (ZnO NPs) have remarkably demonstrated their potential in the diagnosis and treatment of various types of cancers due to their biocompatibility, biodegradability, and unique physico-chemical attributes. ZnO NPs showed cancer cell specific toxicity via generation of reactive oxygen species and destruction of mitochondrial membrane potential, which leads to the activation of caspase cascades followed by apoptosis of cancerous cells. ZnO NPs have also been used as an effective carrier for targeted and sustained delivery of various plant bioactive and chemotherapeutic anticancerous drugs into tumor cells. In this review, at first we have discussed the role of ZnO NPs in diagnosis and bio-imaging of cancer cells. Secondly, we have extensively reviewed the capability of ZnO NPs as carriers of anticancerous drugs for targeted drug delivery into tumor cells, with a special focus on surface functionalization, drug-loading mechanism, and stimuli-responsive controlled release of drugs. Finally, we have critically discussed the anticancerous activity of ZnO NPs on different types of cancers along with their mode of actions. Furthermore, this review also highlights the limitations and future prospects of ZnO NPs in cancer theranostic.

Despite medical advances, cancer is still one of the most dreaded disorders. Surgery, chemotherapies and radiotherapies have typically been the preferred form of treatment. However, their limited solubility and unstable nature hinder their widespread application. Drug resistance, hair loss, and the destruction of healthy cells are all frequent side effects. Nanotechnology provides new cancer treatment options in this regard and have emerged as an efficient platform in targeting chemotherapies to malignant cells and neoplasms particularly. It has also been known to improve the therapeutic efficacy of radiation based and other modern treatment modalities. All these factors tend to lower the risk of a patient suffering from cancer, thereby increasing its survival. Research on cancer therapy using nanotechnology extends beyond the development of existing drugs to create new ones that are only made possible by the special properties of nanomaterials. Despite being much smaller than cells, nanoparticles are large enough to hold a variety of microscopic substances. Additionally, ligands like small molecules, DNA or RNA strands, peptides, aptamers, or antibodies can be employed to functionalize the relatively large surface area of nanoparticles. These characteristics allow the targeted delivery of many drugs with theranostic action. Their physical characteristics such as energy absorption and re-radiation can also be employed to destroy malignant cells. By enabling therapeutic substances to be enclosed in nanoparticulate materials and delivered specifically to tumours via passive permeation and active internalisation mechanisms, nanomedicine technologies have paved the way for revolutionary targeted cancer therapies. One of the biggest barriers to traditional therapy, resistance, has been discovered to be reduced by employing nanotechnology for therapeutic purposes. Many cancer treatments using nanomedicines are already available on the market, and many more are in advanced stages of development and clinical testing. These treatments use a variety of nanosystems, including metallic nanoparticles, liposomes, quantum dots, carbon nanotubes, polymeric micelles, and nanospheres.

Linum usitatissimum L. (common flax) is one of the oldest domesticated plants. Flax and linseed are terms used to reference this crop. Flax has an average genome size of ca 750 Mb with a genetic potential estimated to encode ca 43,000 genes. It is self-pollinated, diploid, and with a relatively small genome recently released which are key features which make flax an ideal crop for breeding and genetic studies. Its popularity rose again in recent decades since it was defined as a functional food. Indeed, its seed is a rich source of oil particularly rich in omega 3 and lignans. Flax is highly adaptable to modern molecular genetic engineering techniques. Future developments in flax genomic studies would greatly benefit from reduced sequencing costs and new approaches. Many important gene targets involved in key processes, such as α-linolenic acid (ALA) and secoisolariciresinol diglucoside (SDG) biosynthesis during seed development, have been established through transcriptome analysis. The transcriptomic analysis of the development of flax seed is still underdeveloped, however, and this could contribute to a thorough understanding of the crop’s health-modulating effects. The protein content in flaxseed has been reported to range from 10.5% to 31%. The major seed storage proteins include albumins, globulins, and prolamins. Flax seed contains in particular two lectin groups with different localization and physiological functions that may participate in specific adaptation of flax plants to various abiotic stress factors.

Lignans are a group of polyphenols that mimic endogenous estrogen in a structural context. Clear evidence was provided by animal studies and preclinical models that phytoestrogens could have antidiabetic activity in both estrogen-dependent and estrogen-independent pathways. A number of studies, including epidemiological studies and clinical studies conducted in different populations, link lignans, diabetes prevention, and management. Several lignans have been reported as potent antidiabetic compounds, in particular, secoisolariciresinol diglucoside (SDG), the major antidiabetic lignan from flax seeds. SDG have to be converted by the human intestinal microbiota into the bioactive mammalian lignans enterodiol and enterolactone. Most of the published research indicate that SDG may have a great potential to reduce type 1 diabetes mellitus incidence and to delay the development of type 2 diabetes mellitus in humans. Flax (Linum usitatissimum L.) cell cultures can provide an attractive and sustainable resource for the production and extraction of antidiabetic lignans. The advantage of using cell cultures as opposed to whole plants is that they can be used independently of climatic or seasonal considerations. This ensures more reproducible production of economically important bioactive extracts. This chapter provides an overview of the biotechnological approaches to the production of antidiabetic lignans in flax cell cultures.

With the advancements made in the field of plant biotechnology, not only plant traits such as yield, stress tolerance, and nutritional value have been improved but also novel products like edible vaccines, biopharmaceuticals, and even bioplastic have been developed. The first transgenic Arabidopsis thaliana plant was genetically engineered by transforming PHA genes from Alcaligenes eutrophus to biosynthesize polyhydroxyalkanoate (PHA). PHA is a renewable, biodegradable, and environmentally friendly bioplastic providing an alternative to reduce the toxic effects of conventional plastics on environmental and human health. Production of bioplastic from transgenic plants is a cheaper and safer option than bacterial synthesis because in this method, bioplastics are directly produced from CO2, salts, water, and solar energy without altering the quality of bioplastic. The successful production of bioplastic especially the PHA from transgenic plants depends on factors such as designing of an effective transgene vector, selection of superior transformation strategy, and higher expression of transgene without negative influence on plant growth and metabolism. To date, various plant species including Arabidopsis thaliana, Nicotiana tabacum, and Saccharum officinarum have been successfully transformed for the production of PHA. But still some crucial factors such as high accumulation of biopolymer, development of a reliable and simple downstream method, and ecological safety measures need to be addressed for scale-up of these transgenic plants as bioreactors for efficient production of bioplastic. In this book chapter, biosynthesis pathway of PHA in bacteria, its subcellular compartmentalization in transgenic plants, and rationale behind the biosynthesis of PHA in transgenic plants have been reviewed critically.

International audience; The purpose of current study was green synthesis of silver nanoparticles (AgNPs) from seeds and wild Silybum plants in comparison with their respective extracts followed by characterization and biological potency. The biologically synthesized AgNPs were subjected to characterization using techniques like XRD, FTIR, TEM, HPLC and SPE. Highly crystalline and stable NPs were obtained using Silybum wild plant (NP1) and seeds (NP3) with size range between 18.12 and 13.20 nm respectively. The synthesized NPs and their respective extracts revealed a vast range of biological applications showing antibacterial, antioxidant, anti-inflammatory, cytotoxic and antiaging potencies. The highest antioxidant activity (478.23 +/- 1.9 mu M, 176.91 +/- 1.3 mu M, 83.5 +/- 1.6% mu gAAE/mg, 156.32 +/- 0.6 mu gAAE/mg) for ABTS, FRAP, FRSA, TRP respectively was shown by seed extract (NP4) followed by highest value of (117.35 +/- 0.9 mu gAAE/mg) for TAC by wild extract (NP2). The highest antifungal activity (13 mm +/- 0.76) against Candida albicans was shown by NP3 while antibacterial activity of (6 mm against Klebsiella pneumonia) was shown by NP3 and NP4. The highest anti-inflammatory activity (38.56 +/- 1.29 against COX1) was shown by NP2. Similarly, the high value of (48.89 +/- 1.34 against Pentosidine-Like AGEs) was shown by NP4. Also, the high anti-diabetic activity (38.74 +/- 1.09 against a-amylase) was shown by NP4. The extracts and the synthesized NPs have shown activity against hepato-cellular carcinoma (HepG2) human cells. The HPLC analysis revealed that the highest value of silymarin component (silybin B 2289 mg/g DW) was found for NP4. Silydianin is responsible for capping. Among the green synthesized AgNPs and the extracts used, the effect of NP4 was most promising for further use.

Flax lignans and neolignans impart health benefits, particularly in treating different types of cancers, due to their strong phytoestrogenic and antioxidant properties. The present study enhances the comprehension on the biosynthesis of antioxidant lignans and neolignans in root-derived in vitro cultures of flax (both callus and adventitious root). The results presented here clearly showed that the adventitious root culture efficiently produced a higher amount of lignans (at day 40) and neolignans (at day 30) than callus culture of flax. High performance liquid chromatography (HPLC) analysis revealed that the accumulations of secoisolariciresinol diglucoside (SDG, 5.5 mg g&minus, 1 DW (dry weight)) and dehydrodiconiferyl alcohol glucoside (DCG, 21.6 mg/g DW) were 2-fold higher, while guaiacylglycerol-&beta, coniferyl alcohol ether glucoside (GGCG, 4.9 mg/g DW) and lariciresinol glucoside (LDG, 11.9 mg/g DW) contents were 1.5-fold higher in adventitious root culture than in callus culture. Furthermore, the highest level of total phenolic production (119.01 mg/L), with an antioxidant free radical scavenging activity of 91.01%, was found in adventitious root culture at day 40, while the maximum level of total flavonoid production (45.51 mg/L) was observed in callus culture at day 30 of growth dynamics. These results suggest that adventitious root culture can be a good candidate for scaling up to industrial level to commercially produce these pharmacologically and nutritionally valuable metabolites.

Serotonin (5-hydroxytryptamine; 5-HT) is an indoleamine neurotransmitter deriving from tryptophan and is present in almost every single living being on earth such as humans, animals and plants, and regulates numerous physiological functions. It is considered as a vital signalling molecule in plants and animals. 5-HT modulates both growth and developmental processes in plants through different mechanisms. This chapter focuses on the interaction of 5-HT with the signalling pathways known to modulate various aspects of growth and developmental processes in plants such as root architecture, shoot organogenesis, flowering and reproduction as well as pigmentation, senescence and defence responses. Special emphasis has been given to calcium signalling, auxin phytohormones interaction, antioxidant activity and reactive oxygen species signalling. Moreover, we also highlight the different techniques that are currently employed for the analysis, detection and quantification of 5-HT in plants. A brief overview of the history and biosynthesis of 5-HT is also presented.

International audience; The efficient progress in nanotechnology has transformed many aspects of food science and the food industry with enhanced investment and market share. Recent advances in nanomaterials and nanodevices such as nanosensors, nano-emulsions, nanopesticides or nanocapsules are intended to bring about innovative applications in the food industry. In this review, the current applications of nanotechnology for packaging, processing, and the enhancement of the nutritional value and shelf life of foods are targeted. In addition, the functionality and applicability of food-related nanotechnologies are also highlighted and critically discussed in order to provide an insight into the development and evaluation of the safety of nanotechnology in the food industry.

International audience; Leishmaniasis is a widely distributed protozoan vector-born disease affecting almost 350 million people. Initially, chemotherapeutic drugs were employed for leishmania treatment but they had toxic side effects. Various nanotechnology-based techniques and products have emerged as anti-leishmanial drugs, including liposomes, lipid nano-capsules, metal and metallic oxide nanoparticles, polymeric nanoparticles, nanotubes and nanovaccines, due to their unique properties, such as bioavailability, lowered toxicity, targeted drug delivery, and biodegradability. Many new studies have emerged with nanoparticles serving as promising therapeutic agent for anti-leishmanial disease treatment. Liposomal Amphotericin B (AmB) is one of the successful nano-based drugs with high efficacy and negligible toxicity. A new nanovaccine concept has been studied as a carrier for targeted delivery. This review discusses different nanotechnology-based techniques, materials, and their efficacies in leishmaniasis treatment and their futuristic improvements.

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.

The use of plants and plant-derived materials for biosynthesis of zinc oxide nanoparticles (ZnO NPs) is developing into a lucrative field of green nanotechnology and gaining more importance owing to its simplicity, rapidity, and eco-friendliness. In present study, a novel and efficient green approach has been developed for biosynthesis of ZnO NPs by exploiting the in vitro platform of plants. Two different in vitro cultures extracts i.e.; callus extract (CE) and adventitious root extract (RE) of Flax were used as a source of reducing and stabilizing agents. Phytochemical analysis revealed that the RE was rich in phytochemical reducing agents as compared to CE. UV-visible spectroscopy showed that the bioreduction of RE-mediated ZnO NPs completed in shorter time than CE-mediated ZnO NPs. Scanning electron microscopy showed that CE-mediated ZnO NPs were spherical with weak agglomeration but the RE-mediated ZnO NPs were hexagonal in shape with uniform distribution of particles. X-ray diffraction analysis showed that the both type of ZnO NPs exhibited the same crystalline nature (wurtzite hexagonal) but vary in their sizes. RE-mediated ZnO NPs were smaller in size (34.97 nm) than CE-mediated ZnO NPs (61.44 nm). Fourier-transform infrared spectroscopy revealed that the polyphenols (lignans), carboxylic acids and aromatic compounds were mainly involved in reduction and capping of both type of ZnO NPs. Moreover, the RE-mediated ZnO NPs showed more potent antibacterial and antileishmanial activity against multidrug resistant bacterial strains and parasite of Leishmania major than CE-mediated ZnO NPs. The present work highlighted the potent role of in vitro cultures of Flax in enhanced biosynthesis, antibacterial and antileishmanial activities of ZnO NPs.

International audience; During the last few decades major advances have shed light on nanotechnology. Nanomaterials have been widely used in various fields such as medicine, energy, cosmetics, electronics, biotechnology and pharmaceuticals. Owing to their unique physicochemical characteristics and nanoscale structures, nanoparticles (NPs) have the capacity to enter into plant cells and interact with intracellular organelles and various metabolites. The effects of NPs on plant growth, development, physiology and biochemistry have been reported, but their impact on plant specialized metabolism (aka as secondary metabolism) still remains obscure. In reaction to environmental stress and elicitors, a common response in plants results in the production or activation of different types of specialized metabolites (e.g., alkaloids, terpenoids, phenolics and flavonoids). These plant specialized metabolites (SMs) are important for plant adaptation to an adverse environment, but also a huge number of them are biologically active and used in various commercially-valued products (pharmacy, cosmetic, agriculture, food/feed). Due to their wide array of applications, SMs have attracted much attention to explore and develop new strategies to enhance their production in plants. In this context, NPs emerged as a novel class of effective elicitors to enhance the production of various plant SMs. In recent years, many reports have been published regarding the elicitation of SMs by different types of NPs. However, in order to achieve an enhanced and sustainable production of these SMs, in-depth studies are required to figure out the most suitable NP in terms of type, size and/or effective concentration, along with a more complete understanding about their uptake, translocation, internalization and elicitation mechanisms. Herein, we are presenting a comprehensive and critical account of the plant SMs elicitation capacities of the three main classes of nanomaterials (i.e., metallic NPs (MNPs), metal oxide NPs (MONPs) and carbon related nanomaterials). Their different proposed uptake, translocation and internalization pathways as well as elicitation mechanism along with their possible deleterious effect on plant SMs and/or phytotoxic effects are summarized. We also identified and critically discussed the current research gaps existing in this field and requiring future investigation to further improve the use of these nanomaterials for an efficient production of plant SMs.

Flavonoids represent a popular class of industrially important bioactive compounds. They possess valuable health-benefiting and disease preventing properties, and therefore they are an important component of the pharmaceutical, nutraceutical, cosmetical and medicinal industries. Moreover, flavonoids possess significant antiallergic, antihepatotoxic, anti-inflammatory, antioxidant, antitumor, antiviral, and antibacterial as well as cardio-protective activities. Due to these properties, there is a rise in global demand for flavonoids, forming a significant part of the world market. However, obtaining flavonoids directly from plants has some limitations, such as low quantity, poor extraction, over-exploitation, time consuming process and loss of flora. Henceforth, there is a shift towards the in vitro production of flavonoids using the plant tissue culture technique to achieve better yields in less time. In order to achieve the productivity of flavonoids at an industrially competitive level, elicitation is a useful tool. The elicitation of in vitro cultures induces stressful conditions to plants, activates the plant defense system and enhances the accumulation of secondary metabolites in higher quantities. In this regard, nanoparticles (NPs) have emerged as novel and effective elicitors for enhancing the in vitro production of industrially important flavonoids. Different classes of NPs, including metallic NPs (silver and copper), metallic oxide NPs (copper oxide, iron oxide, zinc oxide, silicon dioxide) and carbon nanotubes, are widely reported as nano-elicitors of flavonoids discussed herein. Lastly, the mechanisms of NPs as well as knowledge gaps in the area of the nano-elicitation of flavonoids have been highlighted in this review.

Algae have long been exploited commercially and industrially as food, feed, additives, cosmetics, pharmaceuticals, and fertilizer, but now the trend is shifting towards the algae-mediated green synthesis of nanoparticles (NPs). This trend is increasing day by day, as algae are a rich source of secondary metabolites, easy to cultivate, have fast growth, and are scalable. In recent era, green synthesis of NPs has gained widespread attention as a safe, simple, sustainable, cost-effective, and eco-friendly protocol. The secondary metabolites from algae reduce, cap, and stabilize the metal precursors to form metal, metal oxide, or bimetallic NPs. The NPs synthesis could either be intracellular or extracellular depending on the location of NPs synthesis and reducing agents. Among the diverse range of algae, the most widely investigated algae for the biosynthesis of NPs documented are brown, red, blue-green, micro and macro green algae. Due to the biocompatibility, safety and unique physico-chemical properties of NPs, the algal biosynthesized NPs have also been studied for their biomedical applications, which include anti-bacterial, anti-fungal, anti-cancerous, anti-fouling, bioremediation, and biosensing activities. In this review, the rationale behind the algal-mediated biosynthesis of metallic, metallic oxide, and bimetallic NPs from various algae have been reviewed. Furthermore, an insight into the mechanism of biosynthesis of NPs from algae and their biomedical applications has been reviewed critically.

Linum usitatissimum biosynthesizes lignans and neolignans that are diet and medicinally valuable metabolites. In recent years, zinc oxide nanoparticles (ZnONPs) have emerged as potential elicitors for the enhanced biosynthesis of commercial secondary metabolites. Herein, we investigated the influence of biogenic ZnONPs on both seedlings and stem-derived callus of L. usitatissimum. Seedlings of L. usitatissimum grown on Murashige and Skoog (MS) medium supplemented with ZnONPs (1&ndash, 1000 mg/L) presented the highest antioxidant activity, total phenolic content, total flavonoid content, peroxidase and superoxide dismutase activities at 500 mg/L, while the maximum plantlet length was achieved with 10 mg/L. Likewise, the high-performance liquid chromatography (HPLC) analysis revealed the enhanced production of secoisolariciresinol diglucoside, lariciresinol diglucoside, dehydrodiconiferyl alcohol glucoside and guaiacylglycerol-&beta, coniferyl alcohol ether glucoside in the plantlets grown on the 500 mg/L ZnONPs. On the other hand, the stem explants were cultured on MS media comprising 1-naphthaleneacetic acid (1 mg/L) and ZnONPs (1&ndash, 50 mg/L). The highest antioxidant and other activities with an enhanced rooting effect were noted in 25 mg/L ZnONP-treated callus. Similarly, the maximum metabolites were also accumulated in 25 mg/L ZnONP-treated callus. In both systems, the dose-dependent production of reactive oxygen species (ROS) was recorded, resulting in oxidative damage with a more pronounced toxic effect on in vitro cultures. Altogether, the results from this study constitute a first comprehensive view of the impact of ZnONPs on the oxidative stress and antioxidant responses in seedlings vs. in vitro cultures.

Solanum xanthocarpum is considered an important traditional medicinal herb because of its unique antioxidant, and anti-diabetic, anti-aging, and anti-inflammatory potential. Because of the over exploitation linked to its medicinal properties as well as destruction of its natural habitat, S. xanthocarpum is now becoming endangered and its supply is limited. Plant in vitro culture and elicitation are attractive alternative strategies to produce biomass and stimulate biosynthesis of medicinally important phytochemicals. Here, we investigated the potential influence of seven different monochromatic light treatments on biomass and secondary metabolites accumulation in callus culture of S. xanthocarpum as well as associated biological activities of the corresponding extracts. Among different light treatments, highest biomass accumulation was observed in white light-treated callus culture. Optimum accumulation of total flavonoid contents (TFC) and total phenolic contents (TPC) were observed in callus culture kept under continuous white and blue light respectively than control. Quantification of phytochemicals through HPLC revealed that optimum production of caffeic acid (0.57 &plusmn, 0.06 mg/g DW), methyl-caffeate (17.19 mg/g &plusmn, 1.79 DW), scopoletin (2.28 &plusmn, 0.13 mg/g DW), and esculetin (0.68 &plusmn, 0.07 mg/g DW) was observed under blue light callus cultures. Compared to the classic photoperiod condition, caffeic acid, methyl-caffeate, scopoletin, and esculetin were accumulated 1.7, 2.5, 1.1, and 1.09-folds higher, respectively. Moreover, high in vitro cell free antioxidant, anti-diabetic, anti-aging, and anti-inflammatory activities were closely associated with the production of these secondary metabolites. These results clearly showed the interest to apply multispectral light as elicitor of in vitro callus cultures S. xanthocarpum to promote the production of important phytochemicals, and allow us to propose this system as an alternative for the collection of this endangered species from the wild.

Lignans and neolignans are principal bioactive components of Linum usitatissimum L. (Flax), having multiple pharmacological activities. In present study, we are reporting an authoritative abiotic elicitation strategy of photoperiod regimes along with UV-C radiations. Cell cultures were grown in different photoperiod regimes (24 h-dark, 24 h-light and 16L/8D h photoperiod) either alone or in combination with various doses (1.8-10.8 kJ/m(2)) of ultraviolet-C (UV-C) radiations. Secoisolariciresinol diglucoside (SDG), lariciresinol diglucoside (LDG), dehydrodiconiferyl alcohol glucoside (DCG), and guaiacylglycerol-p-coniferyl alcohol ether glucoside (GGCG) were quantified by using reverse phase-high performance liquid chromatography (RP-HPLC). Results showed that the cultures exposed to UV-C radiations, accumulated higher levels of lignans, neolignans and other biochemical markers than cultures grown under different photoperiod regimes. 3.6 kJ/m(2) dose of UV-C radiations resulted in 1.86-fold (7.1 mg/g DW) increase in accumulation of SDG, 2.25-fold (21.6 mg/g DW) in LDG, and 1.33-fold (9.2 mg/g DW) in GGCG in cell cultures grown under UV + photoperiod than their respective controls. Furthermore, cell cultures grown under UV + dark showed 1.36-fold (60.0 mg/g DW) increase in accumulation of DCG in response to 1.8 kJ/m(2) dose of UV-C radiations. Smilar trends were observed in productivity of SDG, LDG and GGCG. Additionally, 3.6 kJ/m(2) dose of UV-C radiations also resulted in 2.82-fold (195.65 mg/I) increase in total phenolic production, 2.94-fold (98.9 mg/I) in total flavonoid production and 1.04-fold (95%) in antioxidant activity of cell cultures grown under UV + photoperiod. These findings open new dimensions for feasible production of biologically active lignans and neolignans by Flax cell cultures.

Silybum marianum is an important medicinal plant of the family Asteraceae, well known for its set of bioactive isomeric mixture of secondary metabolites "silymarin", primarily acting as a hepato-protective agent. Abiotic stress augments plant secondary metabolism in different plant tissues to withstand harsh environmental fluctuations. In the current study, our aim was to induce drought stress in vitro on S. marianum under the influence of different photoperiod treatments to study the effects, with respect to variations in secondary metabolic profile and plant growth and development. S. marianum was extremely vulnerable to different levels of mannitol-induced drought stress. Water deficiency inhibited root induction completely and retarded plant growth was observed; however, phytochemical analysis revealed enhanced accumulation of total phenolic content (TPC), total flavonoid content (TFC), and total protein content along with several antioxidative enzymes. Secondary metabolic content was positively regulated with increasing degree of drought stress. A dependent correlation of seed germination frequency at mild drought stress and antioxidative activities was established with 2 weeks dark + 2 weeks 16/8 h photoperiod treatment, respectively, whereas a positive correlation existed for TPC and TFC when 4 weeks 16/8 h photoperiod treatment was applied. The effects of drought stress are discussed in relation to phenology, seed germination frequency, biomass build up, antioxidative potential, and secondary metabolites accumulation.

Sumaira Anjum, Bilal Haider Abbasi Department of Biotechnology, Quaid-i-Azam University, Islamabad,Pakistan Abstract: In vitro-derived cultures of plants offer a great potential for rapid biosynthesis of chemical-free antimicrobial silver nanoparticles (AgNPs) by enhancing their phytochemical reducing potential. Here, we developed an efficient protocol for in vitro micropropagation of a high-value endangered medicinal plant species, Phlomis bracteosa, in order to explore its biogenic potential in biomimetic synthesis of antimicrobial AgNPs. Murashige and Skoog medium supplemented with 2.0 mg/L thidiazuron was found to be more efficient in inducing optimum in vitro shoot regeneration (78%±4.09%), and 2.0 mg/L indole-3-butyric acid was used for maximum root induction (86%±4.457%). Antimicrobial AgNPs were successfully synthesized by using aqueous extract (rich in total phenolics and flavonoids content) of in vitro derived plantlets of P. bracteosa. Ultraviolet–visible spectroscopy of synthesized AgNPs showed characteristic surface plasmon band in the range of 420–429 nm. The crystallinity, size, and shape of the AgNPs were characterized by X-ray diffraction and scanning electron microscopy. Face-centered cubic AgNPs of almost uniform spherical size (22.41 nm) were synthesized within a short time (1 hour) at room temperature. Fourier-transform infrared spectroscopy revealed that the polyphenols were mainly responsible for reduction and capping of synthesized AgNPs. Energy dispersive X-ray analysis further endorsed the presence of elemental silver in synthesized AgNPs. These biosynthesized AgNPs displayed significantly higher bactericidal activity against multiple drug-resistant human pathogens. The present work highlighted the potent role of in vitro-derived plantlets of P. bracteosa for feasible biosynthesis of antimicrobial AgNPs, which can be used as nanomedicines in many biomedical applications. Keywords: silver nanoparticles, Phlomis bracteosa, in vitro micropropagation, antimicrobial, multidrug resistant bacteria

Sumaira Anjum, Bilal Haider AbbasiDepartment of Biotechnology, Quaid-i-Azam University, Islamabad, PakistanAbstract: Green synthesis of silver nanoparticles (AgNPs) by using plants is an emerging class of nanobiotechnology. It revolutionizes all domains of medical sciences by synthesizing chemical-free AgNPs for various biomedical applications. In this report, AgNPs were successfully synthesized by using whole plant extract (WPE) and thidiazuron-induced callus extract (CE) of Linum usitatissimum. The phytochemical analysis revealed that the total phenolic and flavonoid contents were higher in CE than that in WPE. Ultraviolet-visible spectroscopy of synthesized AgNPs showed a characteristic surface plasmon band in the range of 410–426nm. Bioreduction of CE-mediated AgNPs was completed in a shorter time than that of WPE-mediated AgNPs. Scanning electron microscopy showed that both types of synthesized AgNPs were spherical in shape, but CE-mediated AgNPs were smaller in size (19–24nm) and more scattered in distribution than that of WPE-mediated AgNPs (49–54nm). X-ray diffraction analysis confirmed crystalline nature (face-centered cubic) of both types of AgNPs. Fourier-transform infrared spectroscopy revealed that the polyphenols and flavonoids were mainly responsible for reduction and capping of synthesized AgNPs. Energy dispersive X-ray analysis further confirmed the successful synthesis of AgNPs. Moreover, the synthesized AgNPs were found to be stable over months with no change in the surface plasmon bands. More importantly, CE-mediated AgNPs displayed significantly higher bactericidal activity against multiple drug-resistant human pathogens than WPE-mediated AgNPs. The present work highlighted the potent role of thidiazuron in in vitro-derived cultures for enhanced biosynthesis of chemical-free AgNPs, which can be used as nanomedicines in many biomedical applications.Keywords: silver nanoparticles, Linum usitatissimum L., in vitro cultures, thidiazuron, antimicrobial, multidrug-resistant bacteria