European ferns as rich sources of antioxidants in the human diet

The traditional utilization, biological activity and chemical composition of edible fern species

ETHNOPHARMACOLOGICAL RELEVANCE

Ferns form an important part of the human diet. Young fern fiddleheads are mostly consumed as vegetables, while the rhizomes are often extracted for starch. These edible ferns are also often employed in traditional medicine, where all parts of the plant are used, mostly to prepare extracts. These extracts are applied either externally as lotions and baths or internally as potions, decoctions and teas. Ailments traditionally treated with ferns include coughs, colds, fevers, pain, burns and wounds, asthma, rheumatism, diarrhoea, or skin diseases (eczema, rashes, itching, leprosy).

AIM OF THE REVIEW

This review aims to compile the worldwide knowledge on the traditional medicinal uses of edible fern species correlating to reported biological activities and isolated bioactive compounds.

MATERIALS AND METHODS

The articles and books published on edible fern species were searched through the online databases Web of Science, Pubmed and Google Scholar, with critical evaluation of the hits. The time period up to the end of 2022 was included.

RESULTS

First, the edible fern species were identified based on the literature data. A total of 90 fern species were identified that are eaten around the world and are also used in traditional medicine. Ailments treated are often associated with inflammation or bacterial infection. However, only the most common and well-known fern species, were investigated for their biological activity. The most studied species are Blechnum orientale L., Cibotium barometz (L.) J. Sm., Diplazium esculentum (Retz.) Sw., Marsilea minuta L., Osmunda japonica Thunb., Polypodium vulgare L., and Stenochlaena palustris (Burm.) Bedd. Most of the fern extracts have been studied for their antioxidant, anti-inflammatory and antimicrobial activities. Not surprisingly, antioxidant capacity has been the most studied, with results reported for 28 edible fern species. Ferns have been found to be very rich sources of flavonoids, polyphenols, polyunsaturated fatty acids, carotenoids, terpenoids and steroids and most of these compounds are remarkable free radical scavengers responsible for the outstanding antioxidant capacity of fern extracts. As far as clinical trials are concerned, extracts from only three edible fern species have been evaluated.

CONCLUSIONS

The extracts of edible fern species exert antioxidant anti-inflammatory and related biological activities, which is consistent with their traditional medicinal use in the treatment of wounds, burns, colds, coughs, skin diseases and intestinal diseases. However, studies to prove pharmacological activities are scarce, and require chemical-biological standardization. Furthermore, correct botanical classification needs to be included in publications to simplify data acquisition. Finally, more in-depth phytochemical studies, allowing the linking of traditional use to pharmacological relevance are needed to be done in a standardized way.

The impact of the application of compochar on soil moisture, stress, yield and nutritional properties of legumes under drought stress

Nowadays, when climate change is becoming more and more evident, drought stress plays a very important role, including in agriculture. The increasing number of years with extreme temperatures in the Czech Republic has a negative impact on agricultural production, among other things. Therefore, ways are being sought to reduce these negative impacts. One of them may be the use of compochar (a mixture of compost and biochar) to improve water retention in the soil. The effect of compochar addition on soil properties and crop yield was tested under conditions simulating severe drought stress (greenhouse experiments) compared to normal conditions (field experiments). The aim was to find the most suitable ratio of compochar addition that would reduce the negative effects of drought stress on the yield and quality of peas and beans. Tested soil was only able to retain water between 0.03 and 0.18 cm3/cm3, while the compochar itself retained between 0.12 and 0.32 cm3 cm-3. Three substrate variants were tested by varying the amount of compochar (10, 30 and 50 % v/v) in the soil, and all three substrates showed a similar water content between 0.03 and 0.21 cm3 cm-3 depending on the planted crop and week of cultivation. No apparent stress was observed in crops planted in 100 % compochar. Nevertheless, in general, the trend of chlorophyll a/b ratio increased with increasing amounts of compochar in the soil, indicating stress. Yield increased by approximately 50 % for both test crops when 30 % compochar was used as substrate. The flavonoid content in beans was between 410 and 500 μg CE g-1 DW and in peas was approximately 300 μg CE g-1 DW. The results showed that the utilization of compochar had no effect on either total phenol content, flavonoid content or antioxidant capacity. The combination of compochar with soil (30 %) was found to positively affect the (i) soil moisture, (ii) crop yield, and (iii) nutritional properties of peas and beans and (iv) the ability of plants to withstand drought stress.

Gardenia yellow pigment: Extraction methods, biological activities, current trends, and future prospects

Food coloring plays a vital role in influencing consumers' food choices, imparting vibrant and appealing colors to various food and beverage products. Synthetic food colorants have been the most commonly used coloring agents in the food industry. However, concerns about potential health issues related to synthetic colorants, coupled with increasing consumer demands for food safety and health, have led food manufacturers to explore natural alternatives. Natural pigments not only offer a wide range of colors to food products but also exhibit beneficial bioactive properties. Gardenia yellow pigment is a water-soluble natural pigment with various biological activities, widely present in gardenia fruits. Therefore, this paper aims to delve into Gardenia Yellow Pigment, highlighting its significance as a food colorant. Firstly, a thorough understanding and exploration of various methods for obtaining gardenia yellow pigment. Subsequently, the potential functionality of gardenia yellow pigment was elaborated, especially its excellent antioxidant and neuroprotective properties. Finally, the widespread application trend of gardenia yellow pigment in the food industry was explored, as well as the challenges faced by the future development of gardenia yellow pigment in the field of food and health. Some feasible solutions were proposed, providing valuable references and insights for researchers, food industry professionals, and policy makers.

Anthelmintic activity of European fern extracts against Haemonchus contortus

Most drugs used in the treatment of helminthiasis in humans and animals have lost their efficacy due to the development of drug-resistance in helminths. Moreover, since anthelmintics, like many pharmaceuticals, are now recognized as hazardous contaminants of the environment, returning to medicinal plants and their products represents an environmentally friendly way to treat helminthiasis. The goal of the present study was to test the anthelminthic activity of methanol extracts of eight selected European ferns from the genera Dryopteris, Athyrium and Blechnum against the nematode Haemonchus contortus, a widespread parasite of small ruminants. Eggs and adults of H. contortus drug-susceptible strain ISE and drug-resistant strain WR were isolated from experimentally infected sheep. The efficacy of fern extracts was assayed using egg hatch test and adults viability test based on ATP-level measurement. Among the ferns tested, only Dryopteris aemula extract (0.2 mg/mL) inhibited eggs hatching by 25% in comparison to control. Athyrium distentifolium, Dryopteris aemula and Dryopteris cambrensis were effective against H. contortus adults. In concentration 0.1 mg/mL, A. distentifolium, D. aemula, D. cambrensis significantly decreased the viability of females from ISE and WR strains to 36.2%, 51.9%, 32.9% and to 35.3%, 27.0%, 23.3%, respectively in comparison to untreated controls. None of the extracts exhibited toxicity in precise cut slices from ovine liver. Polyphenol's analysis identified quercetin, kaempferol, luteolin, 3-hydroxybenzoic acid, caffeic acid, coumaric acid and protocatechuic acid as the major components of these anthelmintically active ferns.

Phytochemical Characterization and In Vitro and In Silico Biological Studies from Ferns of Genus Blechnum (Blechnaceae, Polypodiales)

The genus Blechnum represents one of the most ecologically and therapeutically important groups of ferns that grow in tropical, subtropical and temperate regions. In this work, the chemical fingerprint of lyophilized extracts of Blechnum chilense, B. hastatum, B. magellanicum and B. penna-marina species, the determination of their antioxidant activity through ORAC, FRAP and DPPH assays and inhibition of cholinesterase enzymes (AChE and BChE), and an in silico analysis of selected majority compounds on cholinesterase enzymes were identified. Nineteen compounds were recorded for B. chilense, nine in B. hastatum, seventeen in B. magellanicum and seventeen in B. penna-marina by liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-ESI-QTOF-MS). The content of phenolic compounds, flavonoids, antioxidant activity and enzyme inhibition were variable among species, with best results for B. penna-marina. Molecular docking evidenced low toxicities, significant pharmacokinetic properties, and significant binding affinities of the tested compounds for the AChE and BChE enzymes. These fern species show high diversity of bioactive compounds and represent a promising resource in phytotherapy, especially for their optimal levels of phenolic compounds that support their antioxidant activity.

Exploring wild Aspleniaceae ferns as safety sources of polyphenols: The case of Asplenium trichomanes L. and Ceterach officinarum Willd

The forest ecosystem is a source of material resources used since ancient times by mankind. Ferns are part of different oriental systems of traditional medicine due to the phytochemical variety of their fronds, which have allowed their traditional use to be validated through ethnopharmacological studies. In Europe, different cultures have used the same fern with a wide variety of applications due to its presence in most European forests. In recent years, studies on the phytocharacterization and biological activity of the fronds of the main European ferns have been published. In this study, the presence of polyphenolic phytochemicals has been evaluated by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) in the fronds of two wild ferns together with in vitro activities in non-tumoral and human tumoral cell lines. The polyphenols were extracted from Asplenium trichomanes L. and Ceterach officinarum Willd. by cold maceration using methanol. The main phytochemicals of polyphenolic origin in the extracts of A. trichomanes and C. officinarum determined by HPLC-MS/MS were the flavonol hyperoside and the phenolic acid chlorogenic acid, respectively. This different polyphenolic nature of both extracts contributes to the divergence of the behavior experienced in the biological activities tested, but none of the extracts showed a cytotoxic or phototoxic profile in the different tested cell lines. However, the cytoprotective values in front of the H₂O₂ oxidative stress induced in the 3T3 and HaCaT cell lines position these extracts as possible candidates for future health applications.

Sertraline as a new potential anthelmintic against Haemonchus contortus: toxicity, efficacy, and biotransformation

Haemonchus contortus is a parasitic nematode of ruminants which causes significant losses to many farmers worldwide. Since the drugs currently in use for the treatment of haemonchosis are losing their effectiveness due to the drug-resistance of this nematode, a new or repurposed drug is highly needed. As the antipsychotic drug sertraline (SRT) has been shown to be effective against the parasitic nematodes Trichuris muris, Ancylostoma caninum and Schistosoma mansoni, the aim of the present study was to evaluate the possible effect of SRT on H. contortus. The potential hepatotoxicity of SRT was tested in sheep, a common H. contortus host. In addition, the main metabolic pathways of SRT in H. contortus and the ovine liver were identified. While no effect of SRT on H. contortus egg hatching was observed, SRT was found to significantly decrease the viability of H. contortus adults in drug-sensitive and resistant strains, with its effect comparable to the commonly used anthelmintics levamisole and monepantel. Moreover, SRT in anthelmintically active concentrations showed no toxicity to the ovine liver. Biotransformation of SRT in H. contortus was weak, with most of the drug remaining unmetabolized. Production of the main metabolite hydroxy-SRT did not differ significantly between strains. Other minor metabolites such as SRT-O-glucoside, dihydroxy-SRT, and SRT-ketone were also identified in H. contorts adults. Compared to H. contortus, the ovine liver metabolized SRT more extensively, mainly via desmethylation and glucuronidation. In conclusion, the potency of SRT against H. contortus was proven, and it should be tested further toward possible repurposing.

Consumption dietary sources of lycopene, lutein, and zeaxanthin among young adults living in megapolis

Carotenoids are natural antioxidants, affecting apoptosis, absorbing active forms of oxygen, and improving visual performance through their blue light filtering capabilities. Lutein and zeaxanthin are carotenoids of the macular pigment that play a significant role in protecting against age-related macular degeneration (AMD), cataracts, and diabetic retinopathy. We analyzed the dietary sources of lycopene, lutein, and zeaxanthin of young adults living in a megapolis. We analyzed 431 food frequency questionnaires and used two different criteria for comparison: age (groups A1 and A2) and season (groups S1, spring, and S2, autumn). Raw red tomatoes and eggs are the main sources of carotenoids for the majority of respondents regardless of age and season. Significant differences between age groups were found for parsley, carrot, cheeseburger, and spring onion. Foods with high levels of carotenoids (tomato juice, pumpkin, spinach, and sprouts) were absent in the diets of most of the study participants. Watermelons and persimmons are seasonal sources of lycopene, lutein, and zeaxanthin. Dietary sources of carotenoids are present in insufficient quantities in the diets. Foods with high levels of lycopene, lutein, and zeaxanthin are absent or only occasionally included in the diet.

Polypodium vulgare L. (Polypodiaceae) as a Source of Bioactive Compounds: Polyphenolic Profile, Cytotoxicity and Cytoprotective Properties in Different Cell Lines

Pteridophytes, represented by ferns and allies, are an important phytogenetic bridge between lower and higher plants. Ferns have evolved independently of any other species in the plant kingdom being its secondary metabolism a reservoir of phytochemicals characteristic of this taxon. The study of the potential uses of Polypodium vulgare L. (Polypodiaceae) as medicinal plant has increased in recent years particularly when in 2008 the European Medicines Agency published a monograph about the rhizome of this species. Our objective is to provide scientific knowledge on the polar constituents extracted from the fronds of P. vulgare, one of the main ferns of European distribution, to contribute to the validation of certain traditional uses. Specifically, we have characterized the methanolic extract of P. vulgare fronds (PVM) by HPLC-DAD and investigated its potential cytotoxicity, phototoxicity, ROS production and protective effects against oxidative stress by using in vitro methods. The 3T3, HaCaT, HeLa, HepG2, MCF-7 and A549 were the cell lines used to evaluate the possible cytotoxic behaviour of the PVM. HPLC-DAD was utilized to validate the polyphenolic profile of the extract. H₂O₂ and UVA were the prooxidant agents to induce oxidative stress by different conditions in 3T3 and HaCaT cell lines. Antioxidant activity of in vitro PVM in 3T3 and HaCaT cell lines was evaluated by ROS assay. Our results demonstrate that PVM contains significant amounts of shikimic acid together with caffeoylquinic acid derivatives and flavonoids such as epicatechin and catechin; PVM is not cytotoxic at physiological concentrations against the different cell lines, showing cytoprotective and cellular repair activity in 3T3 fibroblast cells. This biological activity could be attributed to the high content of polyphenolic compounds. The fronds of the P. vulgare are a source of polyphenolic compounds, which can be responsible for certain traditional uses like wound healing properties. In the present work, fronds of the common polypody are positioned as a candidate for pharmaceutical applications based on traditional medicine uses but also as potential food ingredients due to lack of toxicity at physiological concentrations.

Culture types and period impact gametophyte morphogenesis and sporophyte formation of eastern bracken

BACKGROUND

Liquid suspension culture efficiently proliferates plant cells and can be applied to ferns because it rapidly increases the fresh weight of gametophytes. This study assessed gametophyte proliferation and sporophyte production of Pteridium aquilinum var. latiusculum using a suspension culture method.

RESULTS

The growth curve linear phase of gametophyte cells was confirmed between 9 and 18 days of culture, and the subculture cycle was determined to be 2 weeks. A double-strength MS medium (fresh weight, 18.0 g) containing 2% sucrose and NH₄⁺:NO₃^- (120 mM, 40:80) was found to be the optimal liquid medium. Gametophytes obtained after suspension culture for 18 days did not normally form sporophytes in an ex vitro soil environment. However, this issue was resolved after changing the culture type or extending the culture period to 6 weeks. A short suspension culture period increased the fresh weight of fragmented and homogenized gametophytes but yielded numerous relatively immature gametophytes (globular forms of branching gametophytes, BG). Furthermore, differences in gametophyte morphogenesis and development were indicated by changes in endogenous phytohormone content. BG with immature development exhibited high accumulation of zeatin, jasmonic acid, and salicylic acid, and relatively low levels of abscisic acid and indole-3-acetic acid. The immature development of gametophytes directly affected sporophyte formation.

CONCLUSIONS

This study maximized the advantages of liquid suspension culture using eastern bracken gametophytes and provides data to resolve any associated issues, thus facilitating efficient bracken production.