Phytochemical Content, Health Benefits, and Toxicology of Common Edible Flowers: A Review (2000-2015)

Edible Flowers: Antioxidant Compounds and Their Functional Properties

Edible flowers have been widely consumed for ages until now. The attractive colors and shapes, exotic aroma, and delightful taste make edible flowers very easy to attain. Moreover, they also provide health benefits for consumers due to the unique composition and concentration of antioxidant compounds in the matrices. Knowing the bioactive compounds and their functional properties from edible flowers is necessary to diversify the usage and reach broader consumers. Therefore, this reported review could be useful for functional product development, engaging the discussed edible flowers. We present a comprehensive review of edible flower composition and the functional properties of their antioxidant compounds, mainly phenolics.

The Emerging Roles of Antioxidant Enzymes by Dietary Phytochemicals in Vascular Diseases

Vascular diseases are major causes of death worldwide, causing pathologies including diabetes, atherosclerosis, and chronic obstructive pulmonary disease (COPD). Exposure of the vascular system to a variety of stressors and inducers has been implicated in the development of various human diseases, including chronic inflammatory diseases. In the vascular wall, antioxidant enzymes form the first line of defense against oxidative stress. Recently, extensive research into the beneficial effects of phytochemicals has been conducted; phytochemicals are found in commonly used spices, fruits, and herbs, and are used to prevent various pathologic conditions, including vascular diseases. The present review aims to highlight the effects of dietary phytochemicals role on antioxidant enzymes in vascular diseases.

The Biodiversity of Edible Flowers: Discovering New Tastes and New Health Benefits

Floriculture and horticulture have always been two parallel and very distinct agronomic realities. Floriculture is concerned with meeting the ornamental needs of our urban ecosystems, while horticulture is based on meeting food requirements. These two activities have now converged toward a food chain where flowers are conceived of as a sort of "new vegetable" and one of the most promising novelties to satisfy the growing need for food innovation both in terms of an organoleptic and nutraceutical profile. This novelty has rapidly evolved, especially following the growing scientific evidence of the human health benefits of flowers used as food. The typically high pigment concentration of the corollas (especially flavonoids and carotenoids), which have evolved to chromatically attract pollinators, indicates a marked nutraceutical activity especially in terms of antioxidant power. In this review, we first attempted to explore which species are most promising and which should be avoided due to real or suspected toxicity problems. The nutraceutical virtues were therefore highlighted trying to focus attention on those "functional phytochemicals" capable of counteracting some specific human pathologies. Furthermore, the organoleptic profile of edible flowers was investigated since this is one of the least known aspects. The cropping systems suitable for their cultivation were therefore hypothesized and finally the criticalities of edible flowers were addressed in terms of shelf life and marketing opportunities.

Nutraceutical potential of dietary phytochemicals in edible flowers-A review

Edible flowers have been in traditional cuisine and phytotherapy for centuries. Recently, the consumption of edible flowers has increased significantly as the phytochemicals in them are known to have numerous health benefits. Information on nutraceutical potentials and health benefits of the phytochemicals available in different varieties of edible flowers and their uses are discussed. It is found that the major groups of dietary phytochemicals in edible flowers include flavonoids, phenolic acids, and anthocyanins and they are capable of exerting antioxidant, anti-inflammatory, anti-diabetic, anticancer, cardioprotective, hepatoprotective gastroprotective, and genoprotective effects. PRACTICAL APPLICATIONS: Edible flowers are good sources of phytochemicals and possessing antioxidant, anti-inflammatory properties, anticancer, anti-diabetic, and cardio-protective properties. However, many edible flowers remain unexplored and underutilized. This review gives eye openings that more in-depth investigations need to be conducted on different edible flowers and they need to be incorporated into commercialized foods and drugs or need to be used for novel nutraceutical development to deliver the potential health benefits to consumers.

Poisonous delicacy: Market-oriented surveys of the consumption of Rhododendron flowers in Yunnan, China

ETHNOPHARMACOLOGICAL RELEVANCE

Plants from the family Ericaceae, and in particular those in the genus Rhododendron are frequently reported to contain grayanotoxins. Plant products such as honey and herbal medicines made from these plants occasionally contain grayanotoxins, and in turn may lead to intoxication. The balance between the benefits and risk of poisoning from Rhododendrons is of concerns. This study explores the ethnobotanical knowledge of the people in Yunnan, China as regards the consumption of Rhododendron flowers, and gives special focus to their assessment of the benefit-risk balance.

MATERIALS AND METHODS

An ethnobotanical survey was conducted across 14 county-level local markets in north and central Yunnan province, during which a total of 82 stalls selling Rhododendron flowers were visited and 204 people were interviewed. Voucher specimens were obtained under the guidance of collectors, and details about local practices and knowledge were recorded using semi-structured interviews and participatory observations.

RESULTS

The consumption of the corollas of Rhododendron decorum Franch. Flowers (RDf) or Rhododendron pachypodum Balf. f. & W.W. Sm. Flowers (RPf) as a seasonal delicacy is a long-standing tradition in the study area. RDf are widely consumed in northwest and northeast Yunnan, while RPf are more prevalent in the central regions of Yunnan, and there is a high consistency in the knowledge of the process for detoxification or palatability for each species. The main reasons for eating the flowers were listed as health benefits (mostly clear heat), wild collected, tradition and good flavor. All RPf consumers stated that the corolla from this species is not toxic, while 67.4% of the RDf consumers claim that the corolla from RDf is toxic. We compared the two species and analyzed their process intensities, poisoning cases and cautions, market trade forms and existing toxicity studies, which agreed well and consistently that the corolla of RDf deserve more toxicity attention than RPf.

CONCLUSION

Our study provides a window to look into the ways, beyond honey and herbal medicine, by which Rhododendron species have influenced human wellbeing. The local culture can justify eating Rhododendron flowers, and meanwhile, has developed a series of skills to avoid the side effects of eating them, and therefore the study also provides a good case to answer more general questions about the rationality of eating any plant products by assessing the trade-off between benefits and side effects.

Phytochemical delivery through nanocarriers: a review

In recent times, phytochemicals encapsulated or conjugated with nanocarriers for delivery to the specific sites have gained considerable research interest. Phytochemicals are mostly plant secondary metabolites which reported to be beneficial for human health and in disease theraphy. However, these compound are large size and polar nature of these compounds, make it difficult to cross the blood-brain barrier (BBB), endothelial lining of blood vessels, gastrointestinal tract and mucosa. Moreover, they are enzymatically degraded in the gastrointestinal tract. Therefore, encapsulation or conjugation of these compounds with nanocrriers could be an alternate way to enhance their bioefficacy by influencing their gastrointestinal stability, rate of absorption and dispersion. This review presents an overview of nanocarriers alternatives which improves therapeutic value and avoid toxicity, by releasing bioactive compounds specifically at target tissues with enhanced stability and bioavailability. Future investigations may emphasize on deciphering the structural changes in nanocarriers during digestion and absorption, the difference between in-vitro and in-vivo digestion simulations, and impact of nanocarriers on the metabolism of phytochemicals.

Phytonutritional Content and Aroma Profile Changes During Postharvest Storage of Edible Flowers

Edible flowers are niche horticultural products, routinely used as cooking ingredients in the food industry. Currently, new species are required with the aim of enlarging the number of species with a long shelf-life, healthy nutraceutical compounds, and new fragrance and tastes. Ageratum houstonianum Mill, Tagetes lemmonii A. Gray, Salvia dorisiana Standl, and Pelargonium odoratissimum (L.) L'Hér "Lemon" were selected for their different morphological characteristics and color. Fresh flowers were analyzed to characterize their phytonutritional content and aroma profile. Postharvest was determined up to 6 days of cold storage at 4°C in transparent polypropylene boxes. Visual quality and cellular membrane damage were observed. The relative content of different antioxidant constituents (e.g., polyphenols, flavonoids, anthocyanins, ascorbic acid), nutritional compounds (soluble sugars, crude proteins), the antioxidant scavenging activity, and the volatile profile were determined and correlated to the quality of shelf-life of the different species. The yellow T. lemmonii freshly picked flowers showed the highest ascorbic acid and flavonoids content, which was maintained during the cold storage, as well as the best visual quality. Limited changes in metabolites were detected in the light blue A. houstonianum during postharvest, although the visual quality is severely compromised. Magenta S. dorisiana and light pink P. odoratissimum showed similar changes in antioxidant constituents during cold storage. For the first time, the volatile compounds have been identified in the four species. Sesquiterpene hydrocarbons are the main class in fresh flowers of A. houstonianum, S. dorisiana, and P. odoratissimum, while monoterpene hydrocarbons are abundant in T. lemmonii. The cold storage influenced mainly P. odoratissimum and S. dorisiana flavor initially dominated by the increase in total monoterpenes at 6 days, reaching a relative content of 90%. Both A. houstonianum and T. lemmonii conserved the prevalence of the same class of constituents in all the analyzed conditions, even though the cold storage influenced the major compound abundance. On the basis of the results, T. lemmonii was the most interesting species with the longest shelf-life due to its phytonutritional and aromatic constituents. Results indicated the peculiar metabolic and physiological attitude of flowers species to cold storage.

The flower head of Chrysanthemum morifolium Ramat. (Juhua): A paradigm of flowers serving as Chinese dietary herbal medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Dietary herbal medicines are widely used for the prevention and treatment of a variety of diseases due to their pharmacological activities in China. Juhua (the flower head of Chrysanthemum morifolium Ramat.), the most representative flower-derived one, which is mainly used for the treatment of respiratory and cardiovascular diseases, shows significant activities, such as antimicrobial, anti-inflammatory, and anticancer, and, neuroprotective, as well as effects on the cardiovascular system.

AIMS OF THIS REVIEW

This review aims to provide an overview of the crucial roles of flowers in Chinese dietary herbal medicine, and the pharmaceutical research progress of Juhua (the paradigm of dietary herbal medicine derived from the flower) including its applications in Traditional Chinese medicine and diet, cultivars, phytochemistry, quality control, pharmacology, and toxicity, along with chrysanthemum breeding and biotechnology.

METHOD

The information associated with Chinese dietary herbal medicine, flower-derived medicine, dietary flower, and pharmaceutical research of Juhua, was collected from government reports, classic books of Traditional Chinese medicine, the thesis of doctors of philosophy and maters, and database including Pubmed, Scifinder, Web of Science, Google Scholar, China National Knowledge Internet; and others.

RESULT

All flower-originated crude medicines recorded in Chinese pharmacopeia and their applications were summarized for the first time in this paper. The edible history and development of flowers in China, the theory of Chinese dietary herbal medicines, as well as flowers serving as dietary herbal medicines, were discussed. Moreover, applications in Traditional Chinese medicine and diet, cultivars, phytochemistry, quality control, pharmacology, and safety evaluation of Juhua, together with chrysanthemum breeding and biotechnology, were summarized in this paper.

CONCLUSION

The theory of dietary herbal medicines, which are an important part of the Traditional Chinese medicine system, has a history of thousands of years. Many herbal flowers, serving as dietary herbal medicines, contribute significantly to the prevention and treatment of a variety of diseases for Chinese people. To better benefit human health, more effective supervision practice for dietary herbal medicines is needed. Although various investigations on Juhua have been done, there is a lack of analytical methods for discrimination of cultivar flowers and identification of authenticity. Research on the major compounds with bioactivities, especially those related to its clinical application or healthcare function, as well as their possible mechanize, need be strengthened. More safety evaluation of Juhua should be carried out. The research limitations Juhua is facing exist in all dietary herbal medicine.

Effects of Different Harvest Times on Nutritional Component of Herbaceous Peony Flower Petals

Herbaceous peony (Paeonia lactiflora Pall.) flowers can be used as edible flowers, but few studies concerned about their edible values and the optimal harvest season. In this study, petals of three herbaceous peony cultivars including “Dafugui,” “Hongyan Zhenghui,” and “Yangfei Chuyu” at four different development stages were used as materials to measure the content of soluble sugar, organic acid, protein, vitamin C (Vc), total phenolics, total flavonoids, mineral elements, and superoxide dismutase (SOD) activity, with the aim to understand the variation tendency of the nutritional ingredients and bioactive components in herbaceous peony flower petals during development and to determine the optimal harvest time for herbaceous peony flowers with better edible qualities. The results demonstrated that the content of individual nutritional and bioactive components was varied with cultivars and developmental stages. The soluble sugar content was 63.69–225.97 mg/g FW, organic acid 10.13–24.60 mg/g FW, soluble protein 9.83–39.17 mg/g FW, Vc 12.31–33.52 mg/100 g FW, total phenolics 83.23–136.19 mg/g DW, total flavonoids 10.20–24.98 mg/g DW, and SOD activity 62.92–284.09 U/g FW. For mineral elements, the content of Na, Mg, K, Ca, Mn, Fe, Ni, and Zn was 20.96–65.51 μg/g DW, 810.85–1342.36 μg/g DW, 6723.68–12253.63 μg/g DW, 848.67–3038.46 μg/g DW, 1.14–8.44 μg/g DW, 48.70–149.72 μg/g DW, 1.20–2.17 μg/g DW, and 16.69–25.50 μg/g DW, respectively. The content of soluble sugar, protein, total flavonoids, and SOD activity in flower petals was the highest, and the content of organic acid was the lowest at the full bloom period (S3) for all three cultivars, while the highest Vc and total phenolics were at the early bloom stage (S2) and flower bud stage (S1), respectively. In conclusion, it is recommended to harvest herbaceous peony flowers at S3 with the best edible quality considering nutrients and bioactive components.

A Snapshot on Food Allergies: A Case Study on Edible Flowers

This perspective study addresses the main causes of adverse reactions to foods in humans, by taking into account the main allergic reactions that may occur as a result of food ingestion, as well the main allergens present in food and how their allergenicity change as a result of food preparation. In addition, European legislation on food labeling and novel foods was taken into account. The case study of this perspective is on the potential allergenicity of edible flowers as well as evidence of phytochemistry and toxic compounds and the risk associated with their ingestion. Regarding edible flowers, a key issue to address is if they are safe to consume or not. In the framework of the project “Innovative activities for the development of the cross-border supply chain of the edible flower” (ANTEA), we considered 62 different species and varieties of edible flowers. The results obtained by consulting two databases on allergens, COMPRISE and Allergen Nomenclature, marked two alerts for two species of edible flowers selected in the project. Moreover, based on edible flower consumption, about ten grams per serving, and on their protein content, we can also state that the risk of allergic reactions due to edible flower ingestion is very low.

Rosemary Flowers as Edible Plant Foods: Phenolic Composition and Antioxidant Properties in Caenorhabditis elegans

Rosmarinus officinalis L., commonly known as rosemary, has been largely studied for its wide use as food ingredient and medicinal plant; less attention has been given to its edible flowers, being necessary to evaluate their potential as functional foods or nutraceuticals. To achieve that, the phenolic profile of the ethanolic extract of R. officinalis flowers was determined using LC-DAD-ESI/MSn and then its antioxidant and anti-ageing potential was studied through in vitro and in vivo assays using Caenorhabditis elegans. The phenolic content was 14.3 ± 0.1 mg/g extract, trans rosmarinic acid being the predominant compound in the extract, which also exhibited a strong antioxidant capacity in vitro and increased the survival rate of C. elegans exposed to lethal oxidative stress. Moreover, R. officinalis flowers extended C. elegans lifespan up to 18%. Therefore, these findings support the potential use of R. officinalis flowers as ingredients to develop products with pharmaceutical and/or nutraceutical potential.

An update on the health benefits promoted by edible flowers and involved mechanisms

The aim of this review is to provide new findings on health effects of edible flowers since 2015. The antioxidant, anti-inflammatory, anti-cancer, hepatoprotective, neuroprotective, anti-diabetic, anti-osteoporosis, anti-obesity, and anti-hypertensive have been reviewed, and the effective concentrations of flower extracts have been summarized. Among all the health benefits mentioned, anti-osteoporosis, anti-obesity, and anti-hypertensive have rarely been mentioned before 2015. Some health benefits mechanisms of edible flowers were discussed frequently after 2015. Some newly found phytochemicals such as polysaccharides were shown to be beneficial to human health. Species of Rosa, Chrysanthemum, and Osmanthus have been reported to exert different health effects on human. For the toxicity studies, the safe level of flower extracts in cell and animal models were at hundreds of parts per million (ppm) level. In consideration of health promoting effects and toxicities of edible flowers, they could serve as potential natural health products for different health benefits.

Trace Elements in Edible Flowers from Italy: Further Insights into Health Benefits and Risks to Consumers

The use of edible flowers in cooking dates back to ancient times, but recently it is gaining success among the consumers, increasingly attentive to healthy and sustainable foods of high quality, without neglecting taste, flavour, and visual appeal. The present study aims to deepen the knowledge regarding the mineral composition of edible flowers, an aspect not widely investigated in scientific literature. The concentrations of Cd, Co, Cu, Fe, Mn, Ni, Pb, Sr, V, and Zn have been determined by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) in flowers belonging to a wide variety of species. The study highlights that some floral species are characterized by significantly higher concentrations of certain trace elements, e.g., the flowers of Acmella oleracea for Mn, those of basil (Ocimum basilicum) and of pumpkins (Cucurbita moschata and C. pepo) for Cu and Sr, and those of orange daylily (Hemerocallis fulva) for Ni. Potentially toxic elements are present at low concentrations, often below the limit of the detection for Cd, Co, Ni, V. In all samples, Cd and Pb are well below the maximum permitted levels in foodstuffs. It can be concluded that the edible flowers analyzed can be considered a good source of essential elements and do not present risks for the consumer health as for the mineral composition.

Bioactive Compounds and Aroma Profile of Some Lamiaceae Edible Flowers

Edible flowers are consumed for their appearance, colours, nutritional and healthy properties, but the use is limited by the actual number of the species. Seven edible flowers of the Lamiaceae family (Ocimeae and Mentheae tribes) were investigated: Monarda didyma ‘Fireball’, Nepeta × faassenii ‘Six Hills Giant’, Ocimum basilicum ‘Blue Spice’, O. basilicum ‘Cinnamon’, Ocimum × citriodorum, Salvia discolor, and Salvia microphylla ‘Hot Lips’. Total soluble sugars, proteins, polyphenols, carotenoids, ascorbic acid and antioxidant activity were detected. The species of the Mentheae tribe contained higher sugar content than Ocimeae flowers, the opposite with regard to protein content. Ocimeae tribe flowers showed high polyphenols and carotenoids content. The Ocimeae tribe together with two specie of the Mentheae tribe showed an aroma profile dominated by sesquiterpene hydrocarbons (58.0% in S. discolor to 77.9% in Ocimum × citriodorum). Oxygenated monoterpenes prevailed in Nepeta and Monarda, also present in the essential oil of this latter species (84.5%). By contrast, Nepeta and S. discolor evidenced non-terpenes as the principal class (41.2% and 77.5%, respectively), while the oxygenated sesquiterpene was the main one in S. microphylla. The two varieties of Ocimum spp. showed oxygenated monoterpenes as the main class of volatiles.

Borage, camellia, centaurea and pansies: Nutritional, fatty acids, free sugars, vitamin E, carotenoids and organic acids characterization

The present study aimed to evaluate the nutritional and bioactive potential of four edible flowers (borage, centaurea, camellia, and pansies). Significant differences were observed among the four. Water was the main constituent (>76%, fresh weight - fw). Linoleic and palmitic acids were the major fatty acids found in borage and red and yellow pansies, while in camellia it was the arachidic acid. In white pansies, behenic and arachidic acids were predominant. Concerning vitamin E, α-tocopherol was the major vitamer. Carotenoids values varied between 5.8 and 181.4 mg β-carotene/100 g dry weight (dw) in centaurea and borage, respectively, being particularly rich in lutein. Malic acid was the major organic acid, except in centaurea, where succinic acid was predominant. Fructose, glucose and sucrose were detected in all flowers. These results can contribute to the knowledge of these edible flowers and consequently increase their popularity among consumers and in the food industry.

Effect of Rose Syrup and Marigold Powder on the Physicochemical, Phytochemical, Sensorial and Storage Properties of Nutricereals and Milk-Based Functional Beverage

ABSTACTAim: The present study aimed to investigate the effect of rose sirup and marigold powder on the physicochemical properties, bioactive potential, sensory acceptability and storage life of the nutricereals (finger millet, oats) and milk-based functional beverage (FB).Method: Preliminary trials were performed using different levels of rose sirup (8-14%) and marigold powder (0.40-0.55%) in the pre-standardized FB. The most acceptable concentration was selected on the basis of sensory analysis. Selected beverages were then subjected to the physicochemical analysis, assessment of bioactive compounds and FTIR characterization. The effect of flower extracts on the mineral content and storage life (4 ± 1 °C) of beverages was also studied. The significant difference in treatments was determined using Duncan's multiple range test, SPSS 25.0.Results: The best acceptable concentrations for rose sirup and marigold powder were 10% and 0.50%, respectively. A significant (p ≤ 0.05) decrease in the dietary fiber (6.50%) and β-glucan (3.95%) content was observed on the addition of rose sirup. Significant (p ≤ 0.05) increase in the total phenols (119.18-145.23%), β-carotene (0.37%), anthocyanins (78.82-230.58%) and antioxidant activity (4.98-7.17%) was observed on the addition of flower extracts. Strong peaks were observed in the regions of 3600-3200, 3000-2800 and 1700-1600 cm ^- 1 on FTIR characterization. A significant decrease in the mineral content of FB was also found on the addition of rose sirup. Rose flavored beverage had the highest overall acceptability (7.83 ± 0.23) and storage stability (50 days at refrigerated storage) among the prepared beverages.Conclusion: The addition of flower extracts significantly improved the acceptability of the prepared beverages. It not only improved the phytochemical profile but also had a substantial impact on storage stability.

A Green Extraction Process for Polyphenols from Elderberry (Sambucus nigra) Flowers Using Deep Eutectic Solvent and Ultrasound-Assisted Pretreatment

Sambucus nigra flowers, known as elderberry flowers (EBF), are a plant tissue rich in polyphenolic phytochemicals with important bioactivities. However, there are few studies dealing with the production of polyphenol-containing EBF extracts. The objective of the investigation presented herein was the development of a high-performance green extraction methodology, to generate EBF extracts enriched in polyphenolic substances, using an efficient deep eutectic solvent, combined with ultrasonication pretreatment. The DES was composed of L-lactic acid (hydrogen bond donor—HBD) and glycine (hydrogen bond acceptor—HBA) and, after an initial screening to properly regulate HBD/HBA ratio, the extraction was optimized by deploying response surface methodology. Under the optimized conditions, which were DES/water (85% w/v), liquid-to-solid ratio 60 mL g⁻¹, and stirring speed 200 rounds per minute, the extraction yield in total polyphenols amounted to 121.24 ± 8.77 mg gallic acid equivalents per g dry matter. The integration of ultrasonication prior to the batch stirred-tank extraction boosted polyphenol recovery of up to 174.73 ± 2.62 mg gallic acid equivalents per g dry matter. Liquid chromatography–mass spectrometry analysis showed that the richest EBF extract obtained was dominated by rutin, a di-p-coumaroylquic acid and chlorogenic acid.

Evaluation of Antioxidant Systems and Ascorbate-Glutathione Cycle in Feijoa Edible Flowers at Different Flowering Stages

Background: Feijoa (Acca sellowiana (O. Berg)) was initially introduced as an ornamental plant, but nowadays, it is widely cultivated for the numerous beneficial properties of its edible fruits. Feijoa flowers have been included in the list of edible flowers, but despite this, they are still considered niche products due to consumer skepticism and lack of publicity. Methods: This study evaluated the physicochemical traits, antioxidant system, and ascorbate-glutathione cycle in feijoa flowers at five flowering stages based on the Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie (BBCH) scale. Results: The results showed that the optimal stage to harvest feijoa flower is the F2 stage characterized by high bioactive compounds content. Furthermore, the enzymes involved in oxidative stress and the ascorbate-glutathione cycle showed different trends during the flowering stages. Conclusions: This study provides new evidence to understand the possible role of bioactive compounds and ascorbate-glutathione cycle in the regulation of flower development, defining the optimal stage to harvest flowers.

Evaluation of bioactive compounds and antioxidant capacity of edible feijoa (Acca sellowiana (O. Berg) Burret) flower extracts

Abstract

The research aimed to evaluate the polyphenolic composition and the antioxidant capacity of edible extracts of feijoa (Acca sellowiana (O. Berg) Burret) flowers. Phenolic compounds of whole feijoa flower (FM), feijoa petals (PM) and feijoa petals juice (PJ) were identified by high-performance liquid chromatography coupled with electrospray mass spectrometry and quantified by liquid chromatography coupled with ultraviolet/visible detection. Moreover, the total polyphenol (TP) content was measured spectrophotometrically and the antioxidant capacities of the extracts were evaluated by FRAP, CUPRAC, DPPH^·, and ABTS^·+ assays. The FM showed TP content (395.14 ± 7.91 mg GAE/L) higher than PM and PJ, and exhibited better antioxidant capacities. FM extracts were characterized by the high content of anthocyanins (115.3 ± 3.6 mg/L), flavonols (42.9 ± 3.3 mg/L) and the presence of ellagic acid (7.9 ± 0.2 mg/L) and other galloyltannins. In addition, cyanidin-3-O-glucoside and apigenin were detected in all the three extracts. The present study provided an overview on particular bioactive compounds that characterise different parts of edible feijoa flowers. Among the latter, FM proved to be the most suitable for exploitation in the food and health manufactory.

Graphic abstract

Culinary Medicine and Nature: Foods That Work Together

Culinary medicine is a new evidence-based field in medicine that blends the art of food and cooking with the science of medicine. Intended to be of constructive use to clinicians, patients, and families, this column covers 10 practical ways for eaters to enjoy preparing and choosing foods, meals, and beverages that work to prevent and treat disease and to enhance one's own natural ability to stay and get well. The column also identifies mechanisms by which food and beverages work in the body as culinary medicine. The column identifies what-to-look-for "chef's secrets" for choosing fruits and vegetables at the peak of flavor in your own garden, in supermarkets, and in farmer's markets. Edible flowers, herbs, and spices with special culinary medical value are also described, as are essential ways to choose and also, when necessary, avoid them. Finally, the corporate and professional office is described as an ideal site for nature-based stress reduction and burnout reversal, in which both culinary medicine and the power of nature can be used to reduce the symptoms associated with chronic stress.

Volatilomic Analysis of Four Edible Flowers from Agastache Genus

Volatilomes emitted from edible flowers of two species of Agastache (A. aurantiaca (A.Gray) Lint & Epling, and A. mexicana (Kunth) Lint & Epling) and from two hybrids (Agastache ‘Arcado Pink’ and Agastache ‘Blue Boa’) were investigated using a solid-phase microextraction technique as well as the extraction of its essential oils. Oxygenated monoterpenes were almost always the predominant class (>85%) of volatile organic compounds (VOCs) in each sample of A. aurantiaca, A. ‘Blue Boa’ and A. mexicana, with the exception of A. ‘Arcado Pink’ (38.6%). Pulegone was the main compound in A. aurantiaca (76.7%) and A. ‘Blue Boa’ (82.4%), while geranyl acetate (37.5%) followed by geraniol (16%) and geranial (17%) were the principal ones in A. mexicana. The essential oil composition showed the same behavior as the VOCs both for the main class as well as the major constituent (pulegone) with the same exception for A. mexicana. Total soluble sugars, secondary metabolites (polyphenols, flavonoids and anthocyanins) and antioxidant activity were also investigated to emphasize the nutraceutical properties of these edible flowers.

Nutraceutical potential of tree flowers: A comprehensive review on biochemical profile, health benefits, and utilization

A numerous types of tree flowers are present in nature and few of them such as Rhdodendron, Bauhinia, Mahua, Gulmohar, Palash, Sesbania, Woodfordia, Simbal, etc. are being utilized traditionally as food and medicine by the localities of India. These flowers are rich in phytochemical (flavonoids, anthocyanins, phenolic acids, carotenoids, tannins, saponins) and possessing numerous health benefits (antioxidant activity, anti-inflammation, anti-cancer activity, anti-diabetic activity, hepatoprotective activity). However, because of the low availability (i.e. short blooming period and at limited places) and poor post-harvest life, these flowers are commonly utilized by the local people as food and medicines during their respective flowering times only. A few attempts have been made toward the utilization of some tree flowers (Mahduca longifolia, Rhododendron arboretum), but others are still unexplored and need to be exploited to achieve food and nutritional security as well increase the opportunity of employment and improvement in the socio-economic status of the local tribes. Therefore, to achieve this, the present review was aimed to review and document the status of common edible tree flowers, their phytochemicals potential and, health benefits as well as their utilization as food and medicines.

Gut microbiota, dietary phytochemicals and benefits to human health

Purpose of the review

In this review, we discuss the roles of the gut microbiota, dietary phytochemicals in improving human health. Recent studies have reported that the human gut microbiota can be altered by dietary phytochemicals including phenolics, carotenoids, and dietary fibers. In addition, both pathogenic and nonpathogenic bacteria show regulatory effects with phytochemicals, suggesting potential synergistic effects in the improvement of human gut health and prevention of chronic diseases.

Recent findings

Numerous studies have been conducted on gut microbial alterations induced by phytochemicals, such as phenolics and carotenoids. Butyrate, a short-chain fatty acid produced via bacterial fermentation in the colon, also shows a significantly beneficial effect in the maintenance of gut microbial homeostasis. However, the molecular mechanisms underlying the effects of diets and the interactions of the gut microorganisms remain poorly understood. The gut microbiome profile changes have been observed in chronic inflammation-induced diseases including colitis, Crohn's disease, immune dysfunction, colon cancer, obesity and diabetes. The anti-inflammatory effects of dietary phytochemicals against these diseases may be partially mediated by regulation of microbial profiles. Latest advances in biomedical technology such as the next-generation sequencing (NGS), and continuous cost reduction associated with these technologies, enabled researchers to perform ever-increasing number of large-scale, high-throughput computational analyses to elucidate the potential mechanism of phytochemical-microbiome interactions.

Summary

Information obtained from these studies may provide valuable insights to guide future clinical research for the development of therapeutics, botanicals and drug efficacy testing, many of which will be discussed in this review.

Edible Flowers of Tagetes erecta L. as Functional Ingredients: Phenolic Composition, Antioxidant and Protective Effects on Caenorhabditis elegans

Tagetes erecta L. has long been consumed for culinary and medicinal purposes in different countries. The aim of this study was to explore the potential benefits from two cultivars of T. erecta related to its polyphenolic profile as well as antioxidant and anti-aging properties. The phenolic composition was analyzed by LC-DAD-ESI/MSn. Folin-Ciocalteu, DPPH^·, and FRAP assays were performed in order to evaluate reducing antiradical properties. The neuroprotective potential was evaluated using the enzymes acetylcholinesterase and monoamine oxidase. Caenorhabditis elegans was used as an in vivo model to assess extract toxicity, antioxidant activity, delayed aging, and reduced β-amyloid toxicity. Both extracts showed similar phenolic profiles and bioactivities. The main polyphenols found were laricitin and its glycosides. No acute toxicity was detected for extracts in the C. elegans model. T. erecta flower extracts showed promising antioxidant and neuroprotective properties in the different tested models. Hence, these results may add some information supporting the possibilities of using these plants as functional foods and/or as nutraceutical ingredients.

Deep eutectic solvents used as extraction solvent for the determination of flavonoids from Camellia oleifera flowers by high-performance liquid chromatography

INTRODUCTION

Camellia oleifera flowers are rich in flavonoids, but there has been little attention on their application. A simple and reliable method for determining the content of flavonoids in C. oleifera flowers would be very helpful for the utilisation of agriculture resources.

OBJECTIVE

To develop an efficient analytical method for the determination of flavonoids in C. oleifera flowers by high-performance liquid chromatography-ultraviolet (HPLC-UV) detection.

METHODOLOGY

Preparing an environmentally-friendly and effective solvent - deep eutectic solvents (DESs) - for compound extraction. Then investigating the influential factors of ultrasound-assisted extraction with DESs by the Box-Behnken design combined with response surface methodology.

RESULTS

DES-5 synthesised with choline chloride and lactic acid (1:2) acquired excellent extractability for four flavonoids (quercetin 3-O-rhamnoside, kaempferol 3-O-rhamnoside and their aglycones) with different polarity. The proposed method, which could simultaneously determine four flavonoids with HPLC-UV detection for the first time, displays satisfactory recovery yields and high precision with inter-day relative standard deviation lower than 5.80%.

CONCLUSION

DESs could be promising solvents for efficiently and selectively extracting bioactive compounds from plant materials, and the analytical method for flavonoids of C. oleifera flowers could provide reference value for its application and be used in other plant resources.

Nanoparticles and Controlled Delivery for Bioactive Compounds: Outlining Challenges for New "Smart-Foods" for Health

Nanotechnology is a field of research that has been stressed as a very valuable approach for the prevention and treatment of different human health disorders. This has been stressed as a delivery system for the therapeutic fight against an array of pathophysiological situations. Actually, industry has applied this technology in the search for new oral delivery alternatives obtained upon the modification of the solubility properties of bioactive compounds. Significant works have been made in the last years for testing the input that nanomaterials and nanoparticles provide for an array of pathophysiological situations. In this frame, this review addresses general questions concerning the extent to which nanoparticles offer alternatives that improve therapeutic value, while avoid toxicity, by releasing bioactive compounds specifically to target tissues affected by specific chemical and pathophysiological settings. In this regard, to date, the contribution of nanoparticles to protect encapsulated bioactive compounds from degradation as a result of gastrointestinal digestion and cellular metabolism, to enable their release in a controlled manner, enhancing biodistribution of bioactive compounds, and to allow them to target those tissues affected by biological disturbances has been demonstrated.

Edible flowers as sources of phenolic compounds with bioactive potential

The edible flowers are widely used, but there is still a lot to be done in relation to its bioactive potential and its correlation with the presence of phenolic compounds. The aim of this study was determined the individual phenolic profile in the hydromethanolic extracts and infusion preparations of four different flower samples (Dahlia mignon, Rosa damascena 'Alexandria' and R. gallica 'Francesa' draft in R. canina, Calendula officinalis L., and Centaurea cyanus L.) and their bioactive potential (antioxidant, antiproliferative, and antibacterial capacity). All the studied flowers presented different profiles regarding their phenolic composition and revealed biological potential. The bioactive potential of the studied flowers was moderate, the hydromethanolic extracts of rose petals showed the best results for antioxidant and antibacterial assays, while the antiproliferative properties were only present in some of the tested cell lines, for the hydromethanolic extracts, in which dahlia and rose showed the best results. These results demonstrate that edible flowers can be used as a source of phenolic compounds with bioactive potential, which can be applied in the food sector, as foods and as sources natural ingredients.

Edible Nanoencapsulation Vehicles for Oral Delivery of Phytochemicals: A Perspective Paper

Edible nanoencapsulation vehicles (ENVs) designed for the delivery of phytochemicals have gained increasing research interest. The major driving force for this trend is the potential bioavailability enhancement effect for phytochemicals when delivered via ENVs. ENVs affect the bioefficacy of phytochemicals by influencing their dispersion and gastrointestinal stability, rate and site of release, transportation efficiency across the endothelial layer, systemic circulation and biodistribution, and regulation of gut microflora. Enhanced bioefficacy can be achieved by rational design of the size, surface property, matrix materials, and compartment structure of ENVs according to properties of phytochemicals. Future investigations may lay particular emphasis on examining the relevance between results gained by in vitro digestion simulations and those obtained via in vivo digestion simulations, structural evolutions of ENVs during digestion and absorption, impacts of ENVs on the metabolism of phytochemicals, and using ENVs for deciphering the reciprocal interactions between phytochemicals and gut microbiota.

Supercritical-Carbon Dioxide Fluid Extract from Chrysanthemum indicum Enhances Anti-Tumor Effect and Reduces Toxicity of Bleomycin in Tumor-Bearing Mice

Bleomycin (BLM), a family of anti-tumor drugs, was reported to exhibit severe side effects limiting its usage in clinical treatment. Therefore, finding adjuvants that enhance the anti-tumor effect and reduce the detrimental effect of BLM is a prerequisite. Chrysanthemum indicum, an edible flower, possesses abundant bioactivities; the supercritical-carbon dioxide fluid extract from flowers and buds of C. indicum (CI_SCFE) have strong anti-inflammatory, anti-oxidant, and lung protective effects. However, the role of CI_SCFE combined with BLM treatment on tumor-bearing mice remains unclear. The present study aimed to investigate the potential synergistic effect and the underlying mechanism of CI_SCFE combined with BLM in the treatment of hepatoma 22 (H22) tumor-bearing mice. The results suggested that the oral administration of CI_SCFE combined with BLM could markedly prolong the life span, attenuate the BLM-induced pulmonary fibrosis, suppress the production of pro-inflammatory cytokines (interleukin-6), tumor necrosis factor-α, activities of myeloperoxidase, and malondiadehyde. Moreover, CI_SCFE combined with BLM promoted the ascites cell apoptosis, the activities of caspases 3 and 8, and up-regulated the protein expression of p53 and down-regulated the transforming growth factor-β1 by activating the gene expression of miR-29b. Taken together, these results indicated that CI_SCFE could enhance the anti-cancer activity of BLM and reduce the BLM-induced pulmonary injury in H22 tumor-bearing mice, rendering it as a potential adjuvant drug with chemotherapy after further investigation in the future.

Antioxidant activities of aqueous extracts from 12 Chinese edible flowers in vitro and in vivo

The antioxidant function of edible flowers have attracted increasing interest. However, information is lacking on the impact of edible flowers on oxidative injury including hypoxia-re-oxygenation and hyperlipidemia. The antioxidant activities of aqueous extracts from 12 Chinese edible flowers were assessed in four different antioxidant models, including total antioxidant capacity (TAC), oxygen radical absorbance capacity (ORAC), scavenging hydroxyl radical capacity (SHRC) and scavenging superoxide anion radical capacity (SSARC). Subsequently, the potential antioxidant effects on rat cardiac microvascular endothelial cells (rCMEC) treated with hypoxia-re-oxygenation and hyperlipidemia rats induced by high-fat diet were also evaluated. The highest TAC, ORAC, SHRC and SSARC were Lonicera japonica Thunb., Rosa rugosa Thunb., Chrysanthemum indicum L. and Rosa rugosa Thunb., respectively. Most aqueous extracts of edible flowers exhibited good antioxidant effects on injury of rCMEC induced by hypoxia-re-oxygenation. In addition, the aqueous extracts of Lonicera japonica Thunb., Carthamus tinctorius L., Magnolia officinalis Rehd. et Wils., Rosmarinus officinalis L. and Chrysanthemum morifolium Ramat. could suppress the build-up of oxidative stress by increasing serum superoxide dismutase, glutathion peroxidase, and reducing malonaldehyde concentration in hyperlipidemia rats. These findings provided scientific support for screening edible flowers as natural antioxidants and preventative treatments for oxidative stress-related diseases.