Mechanisms involved in the endothelium-dependent vasodilatory effect of an ethyl acetate fraction of Cyathea phalerata Mart. in isolated rats’ aorta rings

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.

Vasorelaxing effect of Garcinia cowa leaf extract in rat thoracic aorta and its underlying mechanisms

Background and aim

The leaves of Garcinia cowa (G. cowa) are used in Thai traditional medicine to improve blood circulation. However, there is no scientific evidence to confirm this therapeutic claim. Here, we investigated the vasorelaxing effect and its underlying mechanisms of an aqueous extract of G. cowa leaves in rat thoracic aortic rings.

Materials and methods

Dried leaves of G. cowa were extracted with water, followed by phytochemical analysis. Vascular reactivity experiments were performed in isolated rat thoracic aortic rings using an organ bath system. The results were recorded using the data acquisition system Power Lab.

Results

Phytochemical analysis showed that the leaves of G. cowa are rich in polyphenols and flavonoids, especially kaempferol, vitexin, and isovitexin. The G. cowa leaf extract caused a concentration-dependent relaxation of aortic rings. This effect was attenuated by denudation of the endothelium, or by pre-treatment of the aortic rings with l-NAME, ODQ, indomethacin, or glibenclamide, but not with TEA.

Conclusion

This study indicates that G. cowa leaf extract induces vasorelaxation through both endothelium-dependent and endothelium-independent manners. Its mechanism of action mainly involves the production of nitric oxide and prostanoids, as well as opening ATP-sensitive K⁺ channels. The vasorelaxing effect of G. cowa leaf extract is probable promoted by the action of flavonoids.

Vasorelaxant Effects of Syzygium samarangense (Blume) Merr. and L.M.Perry Extract Are Mediated by NO/cGMP Pathway in Isolated Rat Thoracic Aorta

Syzygium samarangense (Blume) Merr. and L.M.Perry is utilized widely in traditional medicine. We have reported previously a wide array of pharmacological properties of its leaf extract, among them anti-inflammatory, antioxidant, hepatoprotective, antidiabetic, antiulcer, and antitrypanosomal activities. We also annotated its chemical composition using LC-MS/MS. Here, we continue our investigations and evaluate the vasorelaxant effects of the leaf extract on aortic rings isolated from rats and explore the possible underlying mechanisms. S. samarangense extract induced a concentration dependent relaxation of the phenylephrine-precontracted aorta in the rat model. However, this effect disappeared upon removing the functional endothelium. Pretreating the aortic tissues either with propranolol or NG-nitro-L-arginine methyl ester inhibited the relaxation induced by the extract; however, atropine did not affect the extract-induced vasodilation. Meanwhile, adenylate cyclase inhibitor, MDL; specific guanylate cyclase inhibitor, ODQ; high extracellular KCl; and indomethacin as cyclooxygenase inhibitor inhibited the extract-induced vasodilation. On the other hand, incubation of S. samarangense extract with aortae sections having their intact endothelium pre-constricted using phenylephrine or KCl in media free of Ca²⁺ showed no effect on the constriction of the aortae vessels induced by Ca²⁺. Taken together, the present study suggests that S. samarangense extract dilates isolated aortic rings via endothelium-dependent nitric oxide (NO)/cGMP signaling. The observed biological effects could be attributed to its rich secondary metabolites. The specific mechanisms of the active ingredients of S. samarangense extract await further investigations.

Integration of computer-simulated practical exercises into undergraduate medical pharmacology education at Mulungushi University, Zambia

PURPOSE

This study was conducted to determine whether a computer simulation of practical exercises in undergraduate medical pharmacology led to the realization of the intended learning outcomes.

METHODS

The study was a descriptive analysis of laboratory classes carried out using computer simulation programs. Five programs were used to teach practical pharmacology to undergraduate medical students at the Mulungushi University School of Medicine and Health Sciences. The study period was January 2018 to December 2019. The computer programs included a pharmacokinetics simulator (CyberPatient), organ bath simulator (OBSim), AutonomiCAL for simulating autonomic pharmacology, and Virtual Cat and Virtual Rat (RatCVS) for simulating cardiovascular pharmacology. Students utilized these programs during their pharmacology laboratory classes, wrote reports, and answered relevant clinical questions.

RESULTS

The 5 programs provided easy and precise platforms for students to explore concepts and demonstrate knowledge of pharmacokinetics, pharmacodynamics, autonomic and cardiovascular pharmacology, and their clinical applications.

CONCLUSION

The programs were effective learning tools. Students' learning was easily assessed based on their laboratory reports. Although the computer programs met medical students' learning needs, wet laboratory exercises are also needed to meet the needs of students who require practical laboratory skills.