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.

Phytochemical profiling and biological activities of Diplazium esculentum (Retz.) Sw.: an edible vegetable fern

OBJECTIVES

Diplazium esculentum (Retz.) Sw. is an edible vegetable fern of the Himalayan region with high nutritional and therapeutic value owing to its richness in various secondary metabolites and both macro and micronutrients.

CONTENT

This updated review discusses the general traditional use, ethnopharmacology, phytochemistry, nutritional value, pharmacology, and toxicity concerns of D. esculentum.

SUMMARY

The plant parts, viz. rhizomes, shoots, fronds and leaves, have immense ethnomedicinal importance, being traditionally used to cure several health disorders. Among other pharmacological effects, this botanical reveals excellent anti-inflammatory, analgesic, antifungal, antibacterial, antioxidant, anti-leishmanial, antioxidant, anaphylactic, antipyretic, anthelmintic and hepatoprotective activities, directly attributed to the presence of many secondary metabolites. From a pharmacological point of view, the excellent antioxidant potential of D. esculentum suggests its promising use for nutraceutical or functional food formulation purposes.

OUTLOOK

Considering the evidences on popular ethnomedicinal uses of D. esculentum as an edible vegetable, its immense bio-potential, and multiple pharmacological roles, there is a huge need to evaluate its therapeutic applications in light of standard clinical trials.

Traditional Uses, Phytochemistry, and Pharmacological Properties of the Genus Blechnum—A Narrative Review

Blechnum L. is a genus belonging to the Blechnaceae family with 236 accepted species that grow in intertropical, subtropical, and southern temperate regions. Several species of the genus have long been used in folk medicines to treat a broad spectrum of ailments, including typhoid, urinary infections, influenza, wounds, pulmonary complaints, blisters, boils, and antihelmintic-related complications. So far, about 91 chemical compounds have been isolated from different parts of 20 Blechnum species. Among these metabolites, phenolic compounds, sterols, and fatty acids are the main constituents. Modern pharmacological investigations revealed several isolated compounds and extracts to exhibit exceptional biological properties including the antioxidant, antimicrobial, anti-inflammatory, anticancer, insecticidal, antitrematocidal and wound healing. In various tests, both quercetin-7′,3′,4′-trimethoxy and phytol metabolites showed potential antioxidant and antitrematocidal properties, while ponasterone exhibited insecticidal activity. Despite having a broad range of traditional medicinal benefits and biological properties, understanding the scientific connotations based on the available data is still challenging. This article presents a comprehensive review of the traditional uses, phytochemical compounds, and pharmacological aspects of the Blechnum species.

Traditional Uses, Phytochemistry, and Pharmacological Properties of the Genus Blechnum—A Narrative Review

Blechnum L. is a genus belonging to the Blechnaceae family with 236 accepted species that grow in intertropical, subtropical, and southern temperate regions. Several species of the genus have long been used in folk medicines to treat a broad spectrum of ailments, including typhoid, urinary infections, influenza, wounds, pulmonary complaints, blisters, boils, and antihelmintic-related complications. So far, about 91 chemical compounds have been isolated from different parts of 20 Blechnum species. Among these metabolites, phenolic compounds, sterols, and fatty acids are the main constituents. Modern pharmacological investigations revealed several isolated compounds and extracts to exhibit exceptional biological properties including the antioxidant, antimicrobial, anti-inflammatory, anticancer, insecticidal, antitrematocidal and wound healing. In various tests, both quercetin-7′,3′,4′-trimethoxy and phytol metabolites showed potential antioxidant and antitrematocidal properties, while ponasterone exhibited insecticidal activity. Despite having a broad range of traditional medicinal benefits and biological properties, understanding the scientific connotations based on the available data is still challenging. This article presents a comprehensive review of the traditional uses, phytochemical compounds, and pharmacological aspects of the Blechnum species.

Potential, risks, and benefits of the extract recycled from Pteris vittata arsenic-rich biomass as a broiler growth promoter

The arsenic-rich biomass of Pteris vittata is a heavy burden to phytoremediation, but the compositions of extracts recycled from arsenic-rich biomass, such as rutin, may promote broiler growth. As such, this extract can be used to reduce the usage of antibiotics in the broiler industry and the cost of phytoremediation at the same time. Therefore, the critical issues for using extract from arsenic-rich biomass as a growth promoter have been studied, including its effective composition, health and environmental risks, and potential benefits and feasibility. Forty-five compounds were identified in the extract, and they were mainly flavonoids, chlorogenic acids, and proanthocyanidins, which can directly or indirectly influence the growth of broiler. The lifetime carcinogenic risks of broiler edible parts may be maximally increased by 4.75 × 10^-9 due to feeding the extract. The arsenic concentration of the farmland fertilized with the excrement from the broiler fed with the extract may increase by 0.00003-0.01857 mg/kg per year. Results revealed a feasible scenario that the sustainability of phytoremediation and broiler industry could be benefited through wastes from each other.

Impact of Drying Processes on Phenolics and In Vitro Health-Related Activities of Indigenous Plants in Thailand

Thailand has vast areas of tropical forests with many indigenous plants, but limited information is available on their phytochemical profile and in vitro inhibitions of enzymatic and nonenzymatic reactions. This study investigated phenolic profiles using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS), antioxidant activities, and in vitro inhibitory activities of 10 indigenous plants on key enzymes related to obesity (lipase), diabetes (α-amylase and α-glucosidase), and Alzheimer's disease (cholinesterases and β-secretase). The nonenzymatic anti-glycation reaction was also investigated. The 10 indigenous plants were Albizia lebbeck (L.) Benth, Alpinia malaccensis (Burm.) Roscoe, Careya arborea Roxb., Diplazium esculentum (Retz.) Swartz, Kaempferia roscoeana Wall., Millettia brandisiana Kurz., Momordica charantia, Phyllanthusemblica L., Zingiber cassumunar Roxb, and Zingiber citriodorum J. Mood & T. Theleide. Preparations were made by either freeze-drying or oven-drying processes. Results suggested that the drying processes had a minor impact on in vitro inhibitions of enzymatic and nonenzymatic reactions (<4-fold difference). P. emblica was the most potent antioxidant provider with high anti-glycation activity (>80% inhibition using the extract concentration of ≤6 mg/mL), while D. esculentum effectively inhibited β-secretase activity (>80% inhibition using the extract concentration of 10 mg/mL). C. arborea exhibited the highest inhibitory activities against lipase (47-51% inhibition using the extract concentration of 1 mg/mL) and cholinesterases (>60% inhibition using the extract concentration of 2 mg/mL), while Mi. brandisiana dominantly provided α-amylase and α-glucosidase inhibitors (>80% inhibition using the extract concentration of ≤2 mg/mL). Information obtained from this research may support usage of the oven-drying method due to its lower cost and easier preparation step for these studied plant species and plant parts. Furthermore, the information on in vitro inhibitions of enzymatic and nonenzymatic reactions could be used as fundamental knowledge for further investigations into other biological activities such as cell culture or in vivo experiments of these health-beneficial plants.

Application of enzyme-digested soy protein hydrolysate on hydroponic-planted lettuce: Effects on phytochemical contents, biochemical profiles and physical properties

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Protein hydrolysates (PH) prepared from soy via enzymatic-digestion method.

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PH tested on hydroponic-planted lettuce.

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Increased phytochemical, chlorophyll and carotenoid contents detected in lettuce.

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Limited improvements in lettuce length and weight observed at 0.01 mg/mL PH.

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Potential PH application as agricultural nutrient supplement for hydroponic plants.

Plant-derived protein hydrolysates (PH) offer many promising benefits and applications. In this paper, PH was prepared from soy-based processing waste via enzymatic-digestion method and supplemented into hydroponic grow medium solution. The hydroponic-planted lettuces were then harvested and assessed for their selected phytochemical contents, biochemical parameters, antioxidative enzymes and mineral contents. Additionally, the lettuce’s physical properties were assessed. Based on our results, increases in three phytochemical contents were observed, in a PH concentration-dependent manner (0–0.01 mg/mL). Similar trends were also observed for chlorophyll and carotenoid contents. Harvested lettuce length and fresh weight peaked at 0.01 mg/mL PH treatment group, but not in a PH concentration-dependent manner. Whereas, for other physical properties (lettuce leaf surface area, root length, root weight), no significant difference was detected. Through this study, we are hoping to contribute toward the potential PH application as agricultural nutrient supplement for hydroponic plants, with accompanied improvements in harvest yields and nutritional contents.

In Silico Approaches to Identify Polyphenol Compounds as α-Glucosidase and α-Amylase Inhibitors against Type-II Diabetes

Type-II diabetes mellitus (T2DM) results from a combination of genetic and lifestyle factors, and the prevalence of T2DM is increasing worldwide. Clinically, both α-glucosidase and α-amylase enzymes inhibitors can suppress peaks of postprandial glucose with surplus adverse effects, leading to efforts devoted to urgently seeking new anti-diabetes drugs from natural sources for delayed starch digestion. This review attempts to explore 10 families e.g., Bignoniaceae, Ericaceae, Dryopteridaceae, Campanulaceae, Geraniaceae, Euphorbiaceae, Rubiaceae, Acanthaceae, Rutaceae, and Moraceae as medicinal plants, and folk and herb medicines for lowering blood glucose level, or alternative anti-diabetic natural products. Many natural products have been studied in silico, in vitro, and in vivo assays to restrain hyperglycemia. In addition, natural products, and particularly polyphenols, possess diverse structures for exploring them as inhibitors of α-glucosidase and α-amylase. Interestingly, an in silico discovery approach using natural compounds via virtual screening could directly target α-glucosidase and α-amylase enzymes through Monte Carto molecular modeling. Autodock, MOE-Dock, Biovia Discovery Studio, PyMOL, and Accelrys have been used to discover new candidates as inhibitors or activators. While docking score, binding energy (Kcal/mol), the number of hydrogen bonds, or interactions with critical amino acid residues have been taken into concerning the reliability of software for validation of enzymatic analysis, in vitro cell assay and in vivo animal tests are required to obtain leads, hits, and candidates in drug discovery and development.

Evaluation of In Vivo Antidiabetic, In Vitro α-Amylase Inhibitory, and In Vitro Antioxidant Activity of Leaves Crude Extract and Solvent Fractions of Bersama abyssinica Fresen (Melianthaceae)

Background.

The leaves of Bersama abyssinica are used for the treatment of diabetes mellitus in folk medicine system of Ethiopia. The present study was done based on the traditional claim of B abyssinica for the treatment of diabetes mellitus.

Methods.

The α-amylase inhibition and antioxidant activities of B abyssinica extracts were evaluated by using 3,5-dinitrosalicylic acid method and diphenyl-2-picrylhydrazyl assay model, respectively. Blood glucose lowering activity of the extracts was studied in 4 animal models; normoglycemic, oral glucose loaded, and streptozotocin-induced diabetic mice models.

Results.

Among the extracts, the crude extract showed the highest α-amylase enzyme inhibition activity with an IC₅₀ of 6.57 μg/mL. The water fraction showed the strongest antioxidant activity with an IC₅₀ of 3.43 μg/mL. The crude extract at doses of 200, and 400 mg/kg showed significant (P < .05) hypoglycemic activity in normoglycemic mice. All doses of the crude extract significantly (P < .05) reduced blood glucose levels of oral glucose-loaded mice. In streptozotocin-induced diabetic mice models, both the crude and solvent fractions showed a significant (P < .05) blood glucose lowering effect as compared with the negative control group post 8 hour treatment.

Conclusion.

The results demonstrated the beneficial biochemical effects of B abyssinica extract by inhibiting α-amylase and scavenging the free radicals. The crude extract and solvent fractions of B abyssinica had significant blood glucose lowering effect in all animal models.

Development of a Pteris vittata L. compound database by widely targeted metabolomics profiling

The objective of this work was the development of a detailed, extensive and reliable database of the metabolomes of P. vittata. Using an ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry system (UPLC-QqQ-MS/MS) and based on the knowledge of retention time and mass spectral characteristics of an in-house collection of authentic standards, we screened for the presence of a large collection of natural compounds. The database represents 359 authenticated metabolites, comprising 220 primary and 139 secondary metabolites (70 flavonoids, 16 phenylpropanoic acid derivatives, five coumarins, two stilbenoids, 14 benzoic acids, nine phenols, 20 alkaloids and three terpenoids). Comparison of the accumulation of these compounds in two tissues showed that the aerial parts were enriched in flavonols, whereas the subterranean parts were enriched in anthocyanins. The comprehensive database developed here will be beneficial in improving the understanding of the chemical basis of plant therapeutic profile using multivariate analysis, with a particular example of antioxidant activity.

Evaluation of in vitro and in vivo Anti-Diabetic, Anti-Hyperlipidemic and Anti-Oxidant Activity of Flower Crude Extract and Solvent Fractions of Hagenia Abyssinica (Rosaceae)

BACKGROUND

The flower of Hagenia abyssinica (Rosaceae) has been used in traditional health systems to treat diabetes mellitus in Ethiopia and Tanzania. However, the antidiabetic activity of this medicinal plant is not scientifically validated and authenticated. The present study aimed to investigate the in vitro and in vivo anti-diabetic activity of flower crude extract and solvent fractions of Hagenia abyssinica.

METHODS

The in vitro α-amylase inhibition and antioxidant activity of the crude extract and solvent fractions of Hagenia abyssinica were evaluated by using 3,5-dinitrosalicylic acid (DNSA) and diphenyl-2-picrylhydrazyl (DPPH) assay model, respectively. Blood glucose lowering activity of 80% methanolic flower crude extract and solvent fraction was studied in four animal models: normoglycemic mice model, oral glucose loaded mice model, single dose-treated streptozotocin-induced diabetic mice model, and repeated dose-treated streptozotocin-induced diabetic mice model. The effect of the crude extract and solvent fraction of Hagenia abyssinica on diabetic lipid profile and body weight was also studied.

RESULTS

The acute toxicity study of Hagenia abyssinica flower extract did not show mortality in the animals at the limit dose of 2g/kg during the observation period. The result of α-amylase enzyme inhibition activity was found in a dose-dependent manner, the strongest activity was shown by ethyl acetate fraction (54.23% inhibition at 800 μg/mL) compared to the standard acarbose having 91.87% inhibition at 800 μg/mL. Among these extracts, the crude extract had the highest antioxidant activity (58.38% inhibition at 500 μg/mL). The crude extract of H. abyssinica showed significant blood glucose-lowering effect on normoglycemic mice and oral glucose loaded mice. In streptozotocin-induced diabetic mice model, the crude extract and ethyl acetate fraction significantly decreased the fasting blood glucose level after 14 days of treatment. There were significant reductions in serum total cholesterol, serum triglycerides, very low-density lipoprotein, and low-density lipoprotein. However, there were significant increments in body weight and high-density lipoprotein as compared to untreated diabetic mice.

CONCLUSION

The result demonstrated the beneficial biochemical effects of Hagenia abyssinica extract by inhibiting α-amylase, scavenging diphenyl-2-picrylhydrazyl (DPPH) and improving serum lipid profile levels. The flower crude extract and solvent fractions of Hagenia abyssinica are effective in lowering blood glucose levels in diabetic and normoglycemic mice. The claimed traditional use as antidiabetic has scientific ground.

Antidiabetic and Antihyperlipidemic Activities of the Leaf Latex Extract of Aloe megalacantha Baker (Aloaceae) in Streptozotocin-Induced Diabetic Model

Background

Diabetes mellitus has become a major public health and economic problem across the globe. The inadequacies, as well as serious adverse effects associated with conventional medicines, led to a determined search for alternative natural therapeutic agents. The leaf latex extract of Aloe megalacantha has been used for the management of diabetes mellitus in Ethiopian folk medicine. This study aimed to evaluate the antidiabetic and antihyperlipidemic effects of the leaf latex extract of A. megalacantha in streptozotocin- (STZ-) induced diabetic model.

Methods

The experimental diabetes was induced in Swiss albino mice by the administration of a single dose of STZ (150 mg/kg), intraperitoneally. The leaf latex extract of A. megalacantha at three different doses (100, 200, and 400 mg/kg) was administered for a period of 14 days. Fasting blood glucose levels (BGLs) were measured by glucose-oxidase and peroxidase reactive strips. After fourteen days, mice from all groups fasted and the blood was collected through puncturing the retroorbit of the eyes under mild anesthetic condition. The collected blood sample was used to determine serum biochemical parameters such as total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), and high-density lipoprotein (HDL) cholesterol. The statistical analysis of results was carried out using one-way analysis (ANOVA) followed by post hoc multiple comparison tests.

Results

Oral administration of A. megalacantha leaf latex extract at doses of 100, 200, and 400 mg/kg daily for 14 days results in a significant (p < 0.05) decrease in fasting BGL as compared to negative control STZ-induced diabetic mice. The leaf latex has significantly reduced the level of TC, TG, and LDL, VLDL cholesterol while a significant (p < 0.05) HDL cholesterol increment was observed.

Conclusions

The findings of the present investigation indicated that the leaf latex of A. megalacantha possessed significant antihyperglycemic and antihyperlipidemic potential which may prove the claimed use of the plant in amelioration of diabetes and associated complications in Ethiopian folk medicine.

Phytochemicals from fern species: potential for medicine applications

Ferns are an important phytogenetic bridge between lower and higher plants. Historically they have been used in many ways by humans, including as ornamental plants, domestic utensils, foods, and in handicrafts. In addition, they have found uses as medicinal herbs. Ferns produce a wide array of secondary metabolites endowed with different bioactivities that could potentially be useful in the treatment of many diseases. However, there is currently relatively little information in the literature on the phytochemicals present in ferns and their pharmacological applications, and the most recent review of the literature on the occurrence, chemotaxonomy and physiological activity of fern secondary metabolites was published over 20 years ago, by Soeder (Bot Rev 51:442-536, 1985). Here, we provide an updated review of this field, covering recent findings concerning the bioactive phytochemicals and pharmacology of fern species.

Effect of hydroalcoholic leaves extract of Indigofera spicata Forssk. on blood glucose level of normal, glucose loaded and diabetic rodents

BACKGROUND

Diabetes mellitus is found in all parts of the world and is rapidly increasing in its coverage with alarming rate especially in Asia and Africa. Research is increasingly done with the aim of developing a relatively safe and efficacious anti-diabetic plant based products. Parallelly, this investigation was carried out to evaluate the effect of the hydro alcoholic leaves crude extract of Indigofera spicata (ISP) on the blood glucose level(BGL) of normoglycemic, oral glucose loaded and alloxan induced diabetic rodents.

METHODS

The animals were randomly divided into five groups (n = 6) for all the aforementioned three models. In all models, group-I mice provided 2%tween-80, group-II were treated with 5 mg/kg glibenclamide and the remaining three groups (III, IV & V) were treated with 100, 200, and 400 mg/kg dose of the extract respectively. Statistical significance of differences in BGLs within and between groups was analyzed by SPSS version-21 using one way ANOVA followed by Tukey's post hoc multiple comparison.

RESULT

200 mg/kg and 400 mg/kg extract treated groups of normoglycemic mice showed significant (p < 0.05) BGL reduction compared to the pre-exposure level. In case of OGTT model BGL reduction was statistically significant (p < 0.05) in only 400 mg/kg exposed groups at the 120 min of post-exposure compared to the initial level. However, the BGL reducing effect of doses of the extract at the 4(th), 6(th) and 10(th) hours of post treatment on diabetic mice was found statistically significant compared to both the negative control (p < 0.001) and their respective pretreatment levels (p < 0.05).

CONCLUSION

As it is claimed in ethnobotanical studies, the hydroalcoholic crude extract of ISP leaves have shown prominent anti-diabetic effect and can be therefore used as a good insight for new anti-diabetic drug source with a call for further studies.