Context: Verbascum phlomoides L. (Scrophulariaceae) (mullein) used in the European folk medicine due to its anti-inflammatory and soothing action on the respiratory tract is thoroughly documented in handbooks and scientific literature. Nevertheless, information regarding the influence of the polyphenol content on pharmacological activity is scarce. Objective: This study explored the antioxidant and anti-inflammatory potential of V. phlomoides polyphenol-rich extract. Materials and methods: Dried mullein flowers (200 g) were subjected to water extraction (60 °C, 2 h, herb/solvent ratio = 1/10 m/v) and further to n-butanol partition. Total phenolics were spectrophotometrically determined and specific compounds were evaluated by HPLC. The antioxidant activity was assessed by the 2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) assay. The anti-inflammatory potential of the extract (50–200 μg/mL) was evaluated in vitro by ELISA measurement of ICAM-1 expression in TNF-α-stimulated endothelial cells and in vivo by the rat paw edema assay. Results: The mullein extract contained 4.18% total polyphenols expressed as gallic acid. The main components identified by HPLC were: rosmarinic acid (14.93 mg/g), caffeic acid (39.96 mg/g), ferulic acid (29.61 mg/g) and quercetin (17.29 mg/g). Acteoside was not detected; aucubin was detected in traces (0.028 mg/g). Depending on concentration, the extract exerted scavenging activity on DPPH radical (EC₅₀ 7.09 mg/mL), significantly inhibited TNF-α-induced ICAM-1 expression by 55–58.8% on human umbilical vein endothelial cells at 100 and 200 μg/mL, but failed to reduce egg-white-induced rat paw edema. Discussion and conclusion: Mullein polyphenols play an important role in exerting the antioxidant effect but have a weak influence on anti-inflammatory activity that is correlated, probably, to a higher content of iridoids and phenylethanoids.

Plant Phenolic Compounds as Immunomodulatory Agents | InTechOpen, Published on: 2017-03-08. Authors: Alice Grigore

Yarrow (Achillea millefolium L.) is one of the best-known and most widespread species.

At present, specific therapies for COVID-19 are not well established, being certain only that the immune system plays a decisive role in the initiation and progression of the disease. Plants have given and continue to give compounds with great efficiency and low toxicity, some of them being a starting point for extremely effective synthetic substances. Although herbal remedies are used mainly for preventive purposes, there are also guidelines issued by some countries that indicate the use of traditional remedies for different stages of COVID-19 disease.Europe has a long and strong tradition of using medicinal plants for therapeutic purposes, but clinical trials for this type of approach are scarce, compared to Asia. In this regard, a bridge between tradition and science, would have a strong impact on the capacity for prevention and treatment of COVID-19. The paper reviews compounds of plant origin that have previously proven effective in counteracting some coronaviruses but also some of their major effects - direct action on virus replicative apparatus (viral entry or replication, action on the viral enzymatic system), collateral action of natural compounds on the immune system and also the contribution of herbal medicine as vaccine adjuvants are tackled.

Eupatorium cannabinum L. (Asteraceae) has been used for a long time for medicinal purposes due to its various pharmacological effects and richness in active compounds such as phenolics, sesquiterpenes, pyrrolizidine alkaloids, and polysaccharides. Despite the high content of compounds that have important roles in medicinal plants, there are still limited literature data regarding this valuable species. The plant was fractioned using chloroform (EC) and distilled water (EA) and HPLC analysis revealed the presence of eupatorin, eupatilin, and quercetin in EC and caffeic acid and rutin in EA. The antiproliferative potential on BT-20, HepG2, Caco-2, and Jurkat cancer cell lines was assessed by MTS test. Jurkat cells were more sensitive to both extracts (IC(50 )of 7.35 +/- 0.35 for EC and 13.77 +/- 2.16 mu g/mL for EA), while the other lines were susceptible only to EC (IC50 88.27 +/- 1.34 on Caco-2 cells and over 100 mu g/mL on BT-20 and HepG2 cells) after 24 h of exposure. In an LPS-induced damage mouse model of endotoxemia, we showed that preventive administration increases the survival times of mice and leads to inhibition of proinflammatory cytokines. Both polar and nonpolar compounds are involved in exerting these effects, but further analytical studies are needed to identify the key responsible compounds and their biochemical pathways.