Dihydrochalcones and Diterpenoids from Pteris ensiformis and Their Bioactivities

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.

Crystal structure of (−)-β-D-19-glucopiranosyl-9,15-dihydroxy kaurenoate, C26H40O9

C26H40O9, orthorhombic, P212121 (no. 19), a = 22.6816(12) Å, b = 7.3911(3) Å, c = 15.6072(8) Å, V = 2616.4(2) Å3, Z = 4, Rgt (F) = 0.0455, wRref (F 2) = 0.1230, T = 273(2) K.

Natural Enantiomers: Occurrence, Biogenesis and Biological Properties

The knowledge that natural products (NPs) are potent and selective modulators of important biomacromolecules (e.g., DNA and proteins) has inspired some of the world's most successful pharmaceuticals and agrochemicals. Notwithstanding these successes and despite a growing number of reports on naturally occurring pairs of enantiomers, this area of NP science still remains largely unexplored, consistent with the adage "If you don't seek, you don't find". Statistically, a rapidly growing number of enantiomeric NPs have been reported in the last several years. The current review provides a comprehensive overview of recent records on natural enantiomers, with the aim of advancing awareness and providing a better understanding of the chemical diversity and biogenetic context, as well as the biological properties and therapeutic (drug discovery) potential, of enantiomeric NPs.

Phenolics from Archidendron clypearia (Jack) I.C.Nielsen protect SH-SY5Y cells against H2O2-induced oxidative stress

Five undescribed phenolics named pithecellobiumin C-G, along with thirteen known ones were isolated from the twigs and leaves of Archidendron clypearia (Jack) I.C.Nielsen. Their structures were elucidated based on comprehensive spectroscopic analyses, combined with computer-assisted structure elucidation software (ACD/Structure Elucidator) and gauge-independent atomic orbitals (GIAO) NMR chemical shift calculations. The absolute configurations were determined by comparison of experimental and calculated specific rotation and ECD curves. These compounds were tested for their neuroprotective activities against H₂O₂-induced injury in human neuroblastoma SH-SY5Y cells by MTT assay. Pithecellobiumin C-E exhibited noticeable neuroprotective effect. Further pharmacological study demonstrated that they could prevent cell death through inhibiting the apoptosis induction. Flow cytometry assays also proved that these compounds could attenuate reactive oxygen species (ROS) level and mitochondrial dysfunction in SH-SY5Y cells.

Efficient enrichment of total flavonoids from Pteris ensiformis Burm. extracts by macroporous adsorption resins and in vitro evaluation of antioxidant and antiproliferative activities

The aim of this work is to develop an efficient and economical method for the enrichment of total flavonoids from Pteris ensiformis Burm. extracts. Resin screening, adsorption kinetics, adsorption isotherms and thermodynamics were successively researched prior to the dynamic adsorption and desorption tests. NKA-II resin was chosen as the best adsorbent, and the adsorption data were best described by the pseudo-second-order kinetics model and Langmuir isotherm model. The optimum enrichment conditions were as follows: for adsorption the total flavonoids concentration, flow rate and volume of sample were 1.84 mg/mL, 2 BV/h and 5 BV, respectively, and for desorption the flavonoids-loaded NKA-II resin column was desorbed by 7 BV of 50% ethanol at a rate of 2 BV/h. The product had a 6.63-fold higher total flavonoids content than crude extracts, and the recovery yield of total flavonoids was 80.65%. Furthermore, flavonoids-enriched extracts exhibited higher in vitro scavenging activity against superoxide anion radical and hydroxyl radical than crude extracts. In addition, higher antiproliferative activity of flavonoids-enriched extracts against MCF-7 and HepG-2 cell lines was also found as compared to the crude extracts. The developed method is appropriate for large-scale enrichment of total flavonoids from Pteris ensiformis Burm. extracts in the food and pharmaceutical industries.

Dihydrochalcones: Methods of Acquisition and Pharmacological Properties-A First Systematic Review

Dihydrochalcones are a class of secondary metabolites, for which demand in biological and pharmacological applications is still growing. They posses several health-endorsing properties and, therefore, are promising candidates for further research and development. However, low content of dihydrochalcones in plants along with their low solubility and bioavailability restrict the development of these compounds as clinical therapeutics. Therefore, chemomicrobial and enzymatic modifications are required to expand their application. This review aims at analyzing and summarizing the methods of obtaining dihydrochalcones and of presenting their pharmacological actions that have been described in the literature to support potential future development of this group of compounds as novel therapeutic drugs. We have also performed an evaluation of the available literature on beneficial effects of dihydrochalcones with potent antioxidant activity and multifactorial pharmacological effects, including antidiabetic, antitumor, lipometabolism regulating, antioxidant, anti-inflammatory, antibacterial, antiviral, and immunomodulatory ones. In addition, we provide useful information on their properties, sources, and usefulness in medicinal chemistry.

Ultrasound-Assisted Extraction of Total Flavonoids from Pteris cretica L.: Process Optimization, HPLC Analysis, and Evaluation of Antioxidant Activity

In the present work, the ultrasonic-assisted extraction (UAE) of total flavonoids (TF) from Pteris cretica L. was optimized by response surface methodology (RSM) on the basis of a single-factor experiment. The optimized UAE parameters were as follows: Ethanol concentration 56.74%, extraction time 45.94 min, extraction temperature 74.27 °C, and liquid/solid ratio 33.69 mL/g. Under the optimized conditions, the total flavonoids yield (TFY) was 4.71 ± 0.04%, which was higher than that obtained by heat reflux extraction (HRE). The extracts were further analyzed by HPLC, and five major flavonoids, including rutin, quercitrin, luteolin, apigenin, and luteolin-7-O-glucoside, were identified and quantified. Furthermore, the results of the antioxidant test showed that the TF extract obtained under optimized UAE conditions exhibited good 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS⁺•), nitric oxide radical (NO•) scavenging activities, and ferrous ion (Fe²⁺) chelating capacity, with IC₅₀ values of 74.49, 82.92, 89.12, and 713.41 µg/mL, respectively. Results indicated that the UAE technique developed in this work was an efficient, rapid, and simple approach for the extraction of flavonoids with antioxidant activity from P. cretica.