Plants strike back: Plant volatiles and their role in indirect defence against aphids.

As sessile organisms, plants have evolved different strategies to defend themselves against various biotic stressors. An important aspect of the complex response of plants to biotic stress is the emission of volatile compounds (VOCs), which are involved in direct and indirect plant defence mechanisms. Indirect plant defences include a range of plant traits that mediate defence against herbivores and play an important ecological role by not only utilising plants' own capabilities, but also signalling and attracting natural enemies of herbivores. Often the combination of volatiles emitted is specific to herbivores; they are consequently recognised by parasites and other predators, providing a clear link between the volatile signature and the prey. In this review, we focus on indirect plant defence and summarise current knowledge and perspectives on relationships between plants, aphids and parasitic wasps.

Thinking for the future: Phytoextraction of cadmium using primed plants for sustainable soil clean-up.

Cadmium (Cd) soil contamination is a global problem for food security due to its ubiquity, toxicity at low levels, persistence, and bioaccumulation in living organisms. Humans' intake of heavy metals is usually due to direct contact with contaminated soil, through the food chain (Cd accumulation in crops and edible plants) or through drinking water in cases of coupled groundwater-surface water systems. Phytoextraction is one of the eco-friendly, sustainable solutions that can be used as a method for soil clean-up with the possibility of re-use of extracted metals through phytomining. Phytoextraction is often limited by the tolerance level of hyperaccumulating plants and the restriction of their growth. Mechanisms of hyperaccumulation of heavy metals in tolerant species have been studied, but there are almost no data on mechanisms of further improvement of the accumulation capacity of such plants. Priming can influence plant stress tolerance by the initiation of mild stress cues resulting in acclimation of the plant. The potential of plant priming in abiotic stress tolerance has been extensively investigated using different types of molecules that are supplemented exogenously to plant organs (roots, leaves, etc.), resulting in enhanced tolerance of abiotic stress. This review focuses on mechanisms of enhancement of plant stress tolerance in hyperaccumulating plants for their exploitation in phytoextraction processes.

The potential of pumpkin seed oil as a functional food-A comprehensive review of chemical composition, health benefits, and safety.

The growing interest in foods that can be beneficial to human health is bringing into focus some products that have been used locally for centuries but have recently gained worldwide attention. One of these foods is pumpkin seed oil, which has been used in culinary and traditional medicine, but recent data also show its use in the pharmaceutical and cosmetic industries. In addition, some sources refer to it as a potential functional food, mainly because it is obtained from pumpkin seeds, which contain many functional components. However, the production process of the oil may affect the content of these components and consequently the biological activity of the oil. In this review, we have focused on summarizing scientific data that explore the potential of pumpkin seed oil as a functional food ingredient. We provide a comprehensive overview of pumpkin seed oil chemical composition, phytochemical content, biological activity, and safety, as well as the overview of production processes and contemporary use. The main phytochemicals in pumpkin seed oil with health-related properties are polyphenols, phytoestrogens, and fatty acids, but carotenoids, squalene, tocopherols, and minerals may also contribute to health benefits. Most studies have been conducted in vitro and support the claim that pumpkin seed oil has antioxidant and antimicrobial activities. Clinical studies have shown that pumpkin seed oil may be beneficial in the treatment of cardiovascular problems of menopausal women and ailments associated with imbalance of sex hormones.

Evaluation of the status quo of polyphenols analysis: Part II-Analysis methods and food processing effects.

Nowadays due to the concern with the environmental impact of analytical techniques and in order to reduce the ecological footprint there is a tendency to use more efficient and faster procedures that use a smaller amount of organic solvents. Polyphenols have been widely studied in plant-based matrices due to their wide and potent biological properties; however there are no standardized procedures both for sample preparation and analysis of these compounds. The second of a two-part review will carry out a critical review of the extraction procedures and analytical methods applied to polyphenols and their selection criteria over a wide range of factors in relation to commerce-associated, environmental, and economic factors. It is foreseen that in the future the analysis of polyphenols in plant-based matrices includes the use of techniques that allow the simultaneous determination of different subclasses of polyphenols using fast, sophisticated, and automated techniques that allow the minimal consumption of solvents.

Kale (Brassica oleracea var. acephala) as a superfood: Review of the scientific evidence behind the statement.

Kale (Brassica oleracea var. acephala) is a cruciferous vegetable, characterized by leaves along the stem, which, in recent years, have gained a great popularity as a ´superfood´. Consequently, in a popular culture it is listed in many ´lists of the healthiest vegetables´. Without the doubt, a scientific evidences support the fact that cruciferous vegetables included in human diet can positively affect health and well-being, but remains unclear why kale is declared superior in comparison with other cruciferous. It is questionable if this statement about kale is triggered by scientific evidence or by some other factors. Our review aims to bring an overview of kale's botanical characteristics, agronomic requirements, contemporary and traditional use, macronutrient and phytochemical content and biological activity, in order to point out the reasons for tremendous kale popularity.

Integrative Approaches for the Identification and Localization of Specialized Metabolites in Tripterygium Roots.

Members of the genus Tripterygium are known to contain an astonishing diversity of specialized metabolites. The lack of authentic standards has been an impediment to the rapid identification of such metabolites in extracts. We employed an approach that involves the searching of multiple, complementary chromatographic and spectroscopic data sets against the Spektraris database to speed up the metabolite identification process. Mass spectrometry-based imaging indicated a differential localization of triterpenoids to the periderm and sesquiterpene alkaloids to the cortex layer of Tripterygium roots. We further provide evidence that triterpenoids are accumulated to high levels in cells that contain suberized cell walls, which might indicate a mechanism for storage. To our knowledge, our data provide first insights into the cell type specificity of metabolite accumulation in Tripterygium and set the stage for furthering our understanding of the biological implications of specialized metabolites in this genus.

Apigenin as neuroprotective agent: Of mice and men.

Neurodegenerative disorders (NDDs) such as Alzheimer's and Parkinson's diseases are the most common age-related pathologies that affect millions of people all over the world. To date, effective therapy for NDDs is not available and current approaches to disease management include neuroprotection strategy with a hope of maintaining and enhancing the function of survising neurons. Of course, such an approach by its own will not offer a cure but is likely to delay the disease progression by ameliorating the increase of neurotoxic agents such reactive oxygen species (ROS) as well as the associated inflammatory cascades. In this regard, natural products including flavonods that offer neuroprotection through multiple mechanisms have gained a lot of interest in recent years. In this communication, evidences from the various experimental models and clinical trials on the therapeutic potential of one promising flavonod, apigenin, is presented. Its chemistry, mechanism of action and potential benefits in the various examples of NDDs are discussed in the light of drug discovery aspects.

Oleanolic Acid Alters Multiple Cell Signaling Pathways: Implication in Cancer Prevention and Therapy.

Nowadays, much attention has been paid to diet and dietary supplements as a cost-effective therapeutic strategy for prevention and treatment of a myriad of chronic and degenerative diseases. Rapidly accumulating scientific evidence achieved through high-throughput technologies has greatly expanded the understanding about the multifaceted nature of cancer. Increasingly, it is being realized that deregulation of spatio-temporally controlled intracellular signaling cascades plays a contributory role in the onset and progression of cancer. Therefore, targeting regulators of oncogenic signaling cascades is essential to prevent and treat cancer. A plethora of preclinical and epidemiological evidences showed promising role of phytochemicals against several types of cancer. Oleanolic acid, a common pentacyclic triterpenoid, is mainly found in olive oil, as well as several plant species. It is a potent inhibitor of cellular inflammatory process and a well-known inducer of phase 2 xenobiotic biotransformation enzymes. Main molecular mechanisms underlying anticancer effects of oleanolic acid are mediated by caspases, 5' adenosine monophosphate-activated protein kinase, extracellular signal-regulated kinase 1/2, matrix metalloproteinases, pro-apoptotic Bax and bid, phosphatidylinositide 3-kinase/Akt1/mechanistic target of rapamycin, reactive oxygen species/apoptosis signal-regulating kinase 1/p38 mitogen-activated protein kinase, nuclear factor-κB, cluster of differentiation 1, CKD4, s6k, signal transducer and activator of transcription 3, as well as aforementioned signaling pathways . In this work, we critically review the scientific literature on the molecular targets of oleanolic acid implicated in the prevention and treatment of several types of cancer. We also discuss chemical aspects, natural sources, bioavailability, and safety of this bioactive phytochemical.

Antimicrobial Properties of Colostrum and Milk.

The growing number of antibiotic resistance genes is putting a strain on the ecosystem and harming human health. In addition, consumers have developed a cautious attitude towards chemical preservatives. Colostrum and milk are excellent sources of antibacterial components that help to strengthen the immunity of the offspring and accelerate the maturation of the immune system. It is possible to study these important defenses of milk and colostrum, such as lactoferrin, lysozyme, immunoglobulins, oligosaccharides, etc., as biotherapeutic agents for the prevention and treatment of numerous infections caused by microbes. Each of these components has different mechanisms and interactions in various places. The compound's mechanisms of action determine where the antibacterial activity appears. The activation of the antibacterial activity of milk and colostrum compounds can start in the infant's mouth during lactation and continue in the gastrointestinal regions. These antibacterial properties possess potential for therapeutic uses. In order to discover new perspectives and methods for the treatment of bacterial infections, additional investigations of the mechanisms of action and potential complexes are required.

Influence of stress hormones on the auxin homeostasis in Brassica rapa seedlings.

KEY MESSAGE : Stress hormones, particularly jasmonic acid, influenced root growth, auxin levels, and transcription of auxin amidohydrolase BrIAR3 in Brassica rapa seedlings, while auxin conjugate synthetases BrGH3.1 and BrGH3.9 were down-regulated by all treatments. The influence of stress hormones: jasmonic acid (JA), salicylic acid (SA), and abscisic acid (ABA) on 1-day-old seedlings of Chinese cabbage (Brassica rapa L. ssp. pekinensis) was investigated with particular focus on auxin levels and the regulation of reversible auxin conjugation as a mechanism of auxin homeostasis. At the physiological level, stress hormones inhibited root growth, where JA was the most prominent inhibitor with an IC50 value 3.1 µM, which is one and two orders of magnitude lower than that found for ABA and SA, respectively. JA treatment significantly increased the total auxin content, by induction of free and conjugated forms. Also, the stress hormones affected the transcription of genes involved in the process of the reversible auxin conjugation: auxin amidohydrolases BrIAR3 and BrILL2, and auxin conjugate synthetases BrGH3.1 and BrGH3.9. JA treatment increased the transcript level of BrIAR3 two-fold, while it did not affect the transcription of BrILL2. SA and ABA down-regulated the transcription of both auxin amidohydrolase genes by 30 %. Transcription of both auxin conjugate synthetases was significantly down-regulated by all treatments by 30-70 %. Among the investigated biochemical stress markers, glutathione along with protein carbonylation appeared the most affected upon treatments. The redox status of the seedlings was shifted to the more oxidized state upon JA and ABA treatments, whereas SA caused more reduced redox state in comparison to the control. The principal component analysis visualized relationship among auxin and stress parameters upon treatments. Accordingly, the role of auxin in stress response of Brassica seedlings was discussed.

A Comparative Analysis of Radical Scavenging, Antifungal and Enzyme Inhibition Activity of 3'-8″-Biflavones and Their Monomeric Subunits.

Biflavonoids are dimeric forms of flavonoids that have recently gained importance as an effective new scaffold for drug discovery. In particular, 3'-8″-biflavones exhibit antiviral and antimicrobial activity and are promising molecules for the treatment of neurodegenerative and metabolic diseases as well as cancer therapies. In the present study, we directly compared 3'-8″-biflavones (amentoflavone, bilobetin, ginkgetin, isoginkgetin, and sciadopitysin) and their monomeric subunits (apigenin, genkwanin, and acacetin) and evaluated their radical scavenging activity (with DPPH), antifungal activity against mycotoxigenic fungi (Alternaria alternata, Aspergillus flavus, Aspergillus ochraceus, Fusarium graminearum, and Fusarium verticillioides), and inhibitory activity on enzymes (acetylcholinesterase, tyrosinase, α-amylase, and α-glucosidase). All the tested compounds showed weak radical scavenging activity, while antifungal activity strongly depended on the tested concentration and fungal species. Biflavonoids, especially ginkgetin and isoginkgetin, proved to be potent acetylcholinesterase inhibitors, whereas monomeric flavonoids showed higher tyrosinase inhibitory activity than the tested 3'-8″-biflavones. Amentoflavone proved to be a potent α-amylase and α-glucosidase inhibitor, and in general, 3'-8″-biflavones showed a stronger inhibitory potential on these enzymes than their monomeric subunits. Thus, we can conclude that 3'-8″-dimerization enhanced acetylcholinesterase, α-amylase, and α-glucosidase activities, but the activity also depends on the number of hydroxyl and methoxy groups in the structure of the compound.

Neuroprotective Potential of Biflavone Ginkgetin: A Review.

Neurological disorders are becoming more common, and there is an intense search for molecules that can help treat them. Several natural components, especially those from the flavonoid group, have shown promising results. Ginkgetin is the first known biflavonoid, a flavonoid dimer isolated from ginkgo (Ginkgo biloba L.). Later, its occurrence was discovered in more than 20 different plant species, most of which are known for their use in traditional medicine. Herein we have summarized the data on the neuroprotective potential of ginkgetin. There is evidence of protection against neuronal damage caused by ischemic strokes, neurotumors, Alzheimer's disease (AD), and Parkinson's disease (PD). Beneficial effects in ischemic strokes have been demonstrated in animal studies in which injection of ginkgetin before or after onset of the stoke showed protection from neuronal damage. AD protection has been the most studied to date. Possible mechanisms include inhibition of reactive oxygen species, inhibition of ß-secretase, inhibition of Aß fibril formation, amelioration of inflammation, and antimicrobial activity. Ginkgetin has also shown positive effects on the relief of PD symptoms in animal studies. Most of the available data are from in vitro or in vivo animal studies, where ginkgetin showed promising results, and further clinical studies should be conducted.

Morpho-Physiological and Hormonal Response of Winter Wheat Varieties to Drought Stress at Stem Elongation and Anthesis Stages.

Drought stress can significantly reduce wheat growth and development as well as grain yield. This study investigated morpho-physiological and hormonal (abscisic (ABA) and salicylic (SA) acids) responses of six winter wheat varieties during stem elongation and anthesis stage as well grain yield-related traits were measured after harvest. To examine drought response, plants were exposed to moderate non-lethal drought stress by withholding watering for 45 and 65% of the volumetric soil moisture content (VSMC) for 14 days at separate experiments for each of those two growth stages. During the stem elongation phase, ABA was increased, confirming the stress status of plants, and SA showed a tendency to increase, suggesting their role as stress hormones in the regulation of stress response, such as the increase in the number of leaves and tillers in drought stress conditions, and further keeping turgor pressure and osmotic adjustment in leaves. At the anthesis stage, heavier drought stress resulted in ABA accumulation in flag leaves that generated an integrated response of maturation, where ABA was not positively correlated with any of investigated traits. After harvest, the variety Bubnjar, followed by Pepeljuga and Andelka, did not significantly decrease the number of grains per ear and 1000 kernel weight (except Andelka) in drought treatments, thus, declaring them more tolerant to drought. On the other hand, Rujana, Fifi, and particularly Silvija experienced the highest reduction in grain yield-related traits, considering them drought-sensitive varieties.

Changes in the content of glucosinolates, polyphenols and carotenoids during lactic-acid fermentation of cruciferous vegetables: A mini review.

Cruciferous vegetables are considered functional foods because of their content of health-related compounds. They are grown and consumed in various cultures around the world. Fermentation as a preservation method for cruciferous vegetables has been used since ancient times. This process results in fermented products that have a unique flavour and odour, high bioactivity, and a distinctly different phytochemical profile than raw vegetables. In this mini review, we summarize data on changes in phytochemical content during lactic-acid fermentation of various cruciferous vegetables. The main focus was on the changes in the group of glucosinolates, polyphenols and carotenoids.

Tissue-Specific Profiling of Biflavonoids in Ginkgo (Ginkgo biloba L.).

Biflavonoids are flavonoid dimers that are much less studied than monomeric flavonoids. Their precise distribution among plants and their role in plants is still unknown. Here, we have developed a HPLC-DAD method that allows us to separate and simultaneously determine the five major biflavonoids (amentoflavone, bilobetin, ginkgetin, isoginkgetin, and sciadopitysin) in ginkgo (Ginkgo biloba L.). We performed tissue-specific profiling of biflavonoids in ten different plant parts: tree bark, twigs bark, twigs without bark, buds, leaf petioles, leaf blades, seed stalks, sarcotesta, nutshells, and kernels. We did not detect biflavonoids in plant parts not in direct contact with the environment (twigs without bark, nutshells, and kernels). We found the highest total biflavonoids content in leaves, where sciadopitysin was predominant. In contrast, in the bark, amentoflavone was the predominant biflavonoid, suggesting that more methylated biflavonoids accumulate in leaves and seeds. This is probably related to their biological function, which remains to be determined.

Differential Accumulation of Metabolites and Transcripts Related to Flavonoid, Styrylpyrone, and Galactolipid Biosynthesis in Equisetum Species and Tissue Types.

Three species of the genus Equisetum (E. arvense, E. hyemale, and E. telmateia) were selected for an analysis of chemical diversity in an ancient land plant lineage. Principal component analysis of metabolomics data obtained with above-ground shoot and below-ground rhizome extracts enabled a separation of all sample types, indicating species- and organ-specific patterns of metabolite accumulation. Follow-up efforts indicated that galactolipids, carotenoids, and flavonoid glycosides contributed positively to the separation of shoot samples, while stryrylpyrone glycosides and phenolic glycosides were the most prominent positive contributors to the separation of rhizome samples. Consistent with metabolite data, genes coding for enzymes of flavonoid and galactolipid biosynthesis were found to be expressed at elevated levels in shoot samples, whereas a putative styrylpyrone synthase gene was expressed preferentially in rhizomes. The current study builds a foundation for future endeavors to further interrogate the organ and tissue specificity of metabolism in the last living genus of a fern family that was prevalent in the forests of the late Paleozoic era.

Biflavonoids: Important Contributions to the Health Benefits of Ginkgo (Ginkgo biloba L.).

Ginkgo (Ginkgo biloba L.) is one of the most distinctive plants, characterized by excellent resistance to various environmental conditions. It is used as an ornamental plant and is recognized as a medicinal plant in both traditional and Western medicine. Its bioactive potential is associated with the presence of flavonoids and terpene trilactones, but many other compounds may also have synergistic effects. Flavonoid dimers-biflavonoids-are important constituents of ginkgophytopharmaceuticals. Currently, the presence of 13 biflavonoids has been reported in ginkgo, of which amentoflavone, bilobetin, sciadopitysin, ginkgetin and isoginkgetin are the most common. Their role in plants remains unknown, but their bioactivity and potential role in the management of human health are better investigated. In this review, we have provided an overview of the chemistry, diversity and biological factors that influence the presence of biflavonoids in ginkgo, as well as their bioactive and health-related properties. We have focused on their antioxidant, anticancer, antiviral, antibacterial, antifungal and anti-inflammatory activities as well as their potential role in the treatment of cardiovascular, metabolic and neurodegenerative diseases. We also highlighted their potential toxicity and pointed out further research directions.

Flavonoids Target Human Herpesviruses That Infect the Nervous System: Mechanisms of Action and Therapeutic Insights.

Human herpesviruses (HHVs) are large DNA viruses with highly infectious characteristics. HHVs can induce lytic and latent infections in their host, and most of these viruses are neurotropic, with the capacity to generate severe and chronic neurological diseases of the peripheral nervous system (PNS) and central nervous system (CNS). Treatment of HHV infections based on strategies that include natural products-derived drugs is one of the most rapidly developing fields of modern medicine. Therefore, in this paper, we lend insights into the recent advances that have been achieved during the past five years in utilizing flavonoids as promising natural drugs for the treatment of HHVs infections of the nervous system such as alpha-herpesviruses (herpes simplex virus type 1, type 2, and varicella-zoster virus), beta-herpesviruses (human cytomegalovirus), and gamma-herpesviruses (Epstein-Barr virus and Kaposi sarcoma-associated herpesvirus). The neurological complications associated with infections induced by the reviewed herpesviruses are emphasized. Additionally, this work covers all possible mechanisms and pathways by which flavonoids induce promising therapeutic actions against the above-mentioned herpesviruses.

Low Temperatures Affect the Physiological Status and Phytochemical Content of Flat Leaf Kale (Brassica oleracea var. acephala) Sprouts.

Consumption of plants in the juvenile stage becomes popular because sprouts are easy to grow, and they can be a tasty source of micro- and macro-nutrients and various phytochemicals. However, some environmental factors during sprout growth can affect their characteristics. In this article, we investigated how low temperatures during cultivation (8 °C) and additional exposure to freezing temperatures (-8 °C) affect the physiological status and phytochemical content of kale (Brassica oleracea var. acephala) sprouts compared to the control grown at 21 °C. We conducted five independent laboratory experiments and found that low temperature significantly increased proline content and decreased sprouts yield. In addition, low temperature caused a significant decrease in carotenoid and flavonoid content, while phenolic acid content and total glucosinolates content increased, but individual glucosinolates were differentially affected. Our results indicate that low temperatures affect the physiological status of kale sprouts and affect the content of phytochemicals.

Antioxidant properties of extracts of wild medicinal mushroom species from Croatia.

Antioxidant activity and total phenol (TP) content of methanol and water extracts of three wild Croatian mushroom species Auricularia auricula-judae (Bull.) Quél., Sarcoscypha austriaca (Sacc.) Boud., and Strobilurus esculentus (Wulfen) Singer were determined and compared with the values obtained for extracts of four cultivated mushrooms Agaricus bisporus (J.E. Lange) Imbach (brown and white strains), Pleurotus ostreatus (Jacq.) P. Kumm., and Lentinus edodes (Berk.) Singer. Spectrophotometric determination of the TP content was performed using the Folin-Ciocalteu method, while antioxidant activity was measured in a reaction with 1,1-diphenyl-2-picrylhydrazyl radical (DPPH assay) and ferric-tripyridyltriazine (Fe3+-TPTZ) complex (FRAP assay). On the average, 5.8-fold higher TP content was observed for water in comparison to methanol extracts of all analyzed mushrooms. Consequently, antioxidant activity was also higher for water extracts, which is evident from the obtained higher values in the FRAP assay and lower EC50 values in the DPPH assay. Among the three tested wild species, the water extract of S. esculentus exhibited the highest concentration of TP, 8.12 mg/g gallic acid equivalents (GAE), the highest reducing power, 19.42 mmol Fe2+/kg, and the best radical scavenging properties, EC50= 13.5 mg/mL.