Nutritional and Health-Promoting Effects of Lichens Used in Food Applications

PURPOSE OF REVIEW

Lichens have a huge significance which is used in nutrition due to the bioactive components within. Lichen is a nutrient-dense resourceful diet nearly every day meal and has long been used as food; also, these valuable natural resources are now being utilized for a wide range of other purposes. The purpose of this review was to evaluate the nutritional and edible qualities of lichens as well as the possible health benefits of lichens. It is interesting to note that lichen is a nutrient-dense and functional food. It is a nutritional resource that can mitigate the effects of malnutrition to some amount.

RECENT FINDINGS

There is an indication that an intake of lichens as natural foods was associated with nutritional and health-promoting properties. Lichens have proven to have theoretically rich nutritional value, and their extracts and active constituents have also been shown to have multiple health benefits. Low-fat content, high carbohydrate, and crude fibre content; plentiful mineral components; and good protein sources are all thought to contribute to lichen's nutritional value. There is a lot of potential for using lichens as an effective food source and ensuring people's food production.

Lichen Depsides and Tridepsides: Progress in Pharmacological Approaches

Depsides and tridepsides are secondary metabolites found in lichens. In the last 10 years, there has been a growing interest in the pharmacological activity of these compounds. This review aims to discuss the research findings related to the biological effects and mechanisms of action of lichen depsides and tridepsides. The most studied compound is atranorin, followed by gyrophoric acid, diffractaic acid, and lecanoric acid. Antioxidant, cytotoxic, and antimicrobial activities are among the most investigated activities, mainly in in vitro studies, with occasional in silico and in vivo studies. Clinical trials have not been conducted using depsides and tridepsides. Therefore, future research should focus on conducting more in vivo work and clinical trials, as well as on evaluating the other activities. Moreover, despite the significant increase in research work on the pharmacology of depsides and tridepsides, there are many of these compounds which have yet to be investigated (e.g., hiascic acid, lassalic acid, ovoic acid, crustinic acid, and hypothamnolic acid).

Potential human health risks of toxic/harmful elements by consumption of Pseudevernia furfuracea

The potential human health risks of some toxic/harmful elements related to the consumption of Pseudevernia furfuracea (L.) Zopf. were investigated. The toxic/harmful elements (cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), manganese (Mn), nickel (Ni), and zinc (Zn)) were determined in P. furfuracea. According to the analysis result, the maximum (max.) toxic/harmful element value was 62 ± 3.1 mg/kg for Mn and minimum (min.) value was 0.19 ± 0.01 mg/kg for Cd. The estimated daily exposure doses (EDEXDs) for men, women and children were dietary (bread) > dietary (tea) > dermal. For dietary (bread) and dietary (tea) non-carcinogenic (HQ) risk was children > women > men. For dermal, HQ risk was women > children > men. Hazard index (HI) value for men was >1 for Cr. HI value for men was 1.36 for Cr. HI value for women was >1 for Cr and Mn. HI values for women were 1.54 for Cr and 1.01 for Mn. Also, the HI value for children was >1 for Cr, Mn, and Pb. HI values for children were 3.44 for Cr, 2.24 for Mn, and 1.66 for Pb. This situation showed that there was a non-carcinogenic risk. Carcinogenic risk values were dietary (bread) > dietary (tea) > dermal. The total max. carcinogenic value was 1.97E-03 for Cr while the total min. carcinogenic value was 1.31E-05 for Pb. As a result, it has been determined that there may be a risk of cancer due to the consumption of lichen as bread and this situation may adversely affect human health.

Lichen Depsidones with Biological Interest

Depsidones are some of the most abundant secondary metabolites produced by lichens. These compounds have aroused great pharmacological interest due to their activities as antioxidants, antimicrobial, and cytotoxic agents. Hence, this paper aims to provide up-to-date knowledge including an overview of the potential biological interest of lichen depsidones. So far, the most studied depsidones are fumarprotocetraric acid, lobaric acid, norstictic acid, physodic acid, salazinic acid, and stictic acid. Their pharmacological activities have been mainly investigated in in vitro studies and, to a lesser extent, in in vivo studies. No clinical trials have been performed yet. Depsidones are promising cytotoxic agents that act against different cell lines of animal and human origin. Moreover, these compounds have shown antimicrobial activity against both Gram-positive and Gram-negative bacteria and fungi, mainly Candida spp. Furthermore, depsidones have antioxidant properties as revealed in oxidative stress in vitro and in vivo models. Future research should be focused on further investigating the mechanism of action of depsidones and in evaluating new potential actions as well as other depsidones that have not been studied yet from a pharmacological perspective. Likewise, more in vivo studies are prerequisite, and clinical trials for the most promising depsidones are encouraged.

Pro-Apoptotic Potential of Pseudevernia furfuracea (L.) Zopf Extract and Isolated Physodic Acid in Acute Lymphoblastic Leukemia Model In Vitro

Acute lymphoblastic leukemia (ALL) is the most frequently diagnosed type of leukemia among children. Although chemotherapy is a common treatment for cancer, it has a wide range of serious side effects, including myelo- and immunosuppression, hepatotoxicity and neurotoxicity. Combination therapies using natural substances are widely recommended to attenuate the adverse effects of chemotherapy. The aim of the present study was to investigate the anti-leukemic potential of extract from the lichen Pseudevernia furfuracea (L.) Zopf (PSE) and isolated physodic acid (Phy) in an in vitro ALL model. A screening assay, flow cytometry and Western blotting were used to analyze apoptosis occurrence, oxidative stress, DNA damage and stress/survival/apoptotic pathway modulation induced by the tested substances in Jurkat cells. We demonstrate for the first time that PSE and Phy treatment-induced intrinsic caspase-dependent cell death was associated with increased oxidative stress, DNA damage and cell cycle arrest with the activation of cell cycle checkpoint proteins p53, p21 and p27 and stress/survival kinases p38 MAPK, JNK and PI3K/Akt. Moreover, using peripheral T lymphocytes, we confirmed that PSE and Phy treatment caused minimal cytotoxicity in normal cells, and therefore, these naturally occurring lichen secondary metabolites could be promising substances for ALL therapy.

Efficiency and selectivity of ionic liquids in microwave-assisted extraction of major lichen phenolic compounds: a scalable process with recycling of ionic liquids

INTRODUCTION

Pseudevernia furfuracea, a lichen used classically for cosmetic applications, contains interesting metabolites possessing antimicrobial and anti-inflammatory or antioxidant properties.

OBJECTIVES

Ionic liquid combined to microwave-assisted extraction (IL-MAE) was successfully applied for metabolites extraction from Pseudevernia furfuracea.

MATERIALS AND METHODS

Three imidazolium and pyridinium-based ionic liquids (ILs): 1,3-dimethylimidazolium methylsulphate [C₁ C₁ Im][MeSO₄ ], 1-ethyl-3-methylimidazolium ethylsulphate [C₂ C₁ Im][EtSO₄ ], and N-ethylpyridinium ethylsulphate [C₂ Py][EtSO₄ ] were assessed for this process. The efficiency of the extraction method was evaluated using thin-layer chromatography (TLC) coupled to a Camag® spectrophotodensitometer and using high-performance liquid chromatography (HPLC) analysis.

RESULTS

ILs under MAE showed extraction time efficiency (15 min vs. 24 h for conventional heating) and high selectivity in extracting the targeted metabolites: atranorin (AT), methyl-β-orcinol carboxylate (MOC), fumarprotocetraric acid (Fum. Ac.), and physodic acid (Phys. Ac.) despite the increased degradation of AT under MAE. We showed a tunable selectivity of ILs towards extracting metabolites by changing anion or cation due to the modification of the interaction between the IL and the metabolites. While [C₂ Py][EtSO₄ ] was the most efficient IL and could extract all the targeted metabolites, [C₂ C₁ Im][EtSO₄ ] was the most selective. It fully extracted AT and partially Fum. Ac. Moreover, the lichen prepared by mixing procedure provided AT and Fum. Ac. more than the milled one. A 100 times scale-up extraction was successfully performed on mixed samples with full IL recycling after back extraction.

CONCLUSION

IL-MAE is reliable for lichen metabolites extraction. The method is reproducible, scalable, with possible IL recycling, opening the door for potential industrial applications.

Neuroprotective effects of boron nitride nanoparticles in the experimental Parkinson's disease model against MPP+ induced apoptosis

Parkinson's disease (PD) is one of the most aggressive neurodegenerative diseases and characterized by the loss of dopamine-sensitive neurons in the substantia nigra region of the brain. There is no any definitive treatment to completely cure PD and existing treatments can only ease the symptoms of the disease. Boron nitride nanoparticles have been extensively studied in nano-biological studies and researches showed that it can be a promising candidate for PD treatment with its biologically active unique properties. In the present study, it was aimed to investigate ameliorative effects of hexagonal boron nitride nanoparticles (hBNs) against toxicity of 1-methyl-4-phenylpyridinium (MPP⁺) in experimental PD model. Experimental PD model was constituted by application of MPP⁺ to differentiated pluripotent human embryonal carcinoma cell (Ntera-2, NT-2) culture in wide range of concentrations (0.62 to 2 mM). Neuroprotective activity of hBNs against MPP⁺ toxicity was determined by cell viability assays including MTT and LDH release. Oxidative alterations by hBNs application in PD cell culture model were investigated using total antioxidant capacity (TAC) and total oxidant status (TOS) tests. The impacts of hBNs and MPP⁺ on nuclear integrity were analyzed by Hoechst 33258 fluorescent staining method. Acetylcholinesterase (AChE) enzyme activities were determined by a colorimetric assay towards to hBNs treatment. Cell death mechanisms caused by hBNs and MPP+ exposure was investigated by flow cytometry analysis. Experimental results showed that application of hBNs increased cell viability in PD model against MPP⁺ application. TAS and TOS analysis were determined that antioxidant capacity elevated after hBNs applications while oxidant levels were reduced. Furthermore, flow cytometric analysis executed that MPP⁺ induced apoptosis was prevented significantly (p < 0.05) after application with hBNs. In a conclusion, the obtained results indicated that hBNs have a huge potential against MPP⁺ toxicity and can be used in PD treatment as novel neuroprotective agent and drug delivery system.

Inhibition of growth of U87MG human glioblastoma cells by Usnea longissima Ach

Herbal medicines are efficient to reduce side effects in the fight against glioblastoma, which plays a critical role within brain cancer species. The recent studies designated for testing the effects of lichens that have shown numerous anticancer activities on glioblastoma so far. In the present study, different concentrations of water extract obtained from Usnea longissima Ach. were used in order to determine cytotoxic (via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase tests), antioxidant (via total antioxidant capacity test), pro-oxidant (via total oxidant status test) and genotoxic (via 8-hydroxy-2'-deoxyguanosine test) effects of them on human U87MG-glioblastoma cancer cell lines. Primary mixed glial-neuronal non-cancerous cells from Sprague-Dawley rats were also utilized to measure the effects of treatments on non-cancerous cells. Based on median inhibitory concentration values, the data belonged to non-cancerous cells (2486.71 mg/L) showed distinct towering compared to U87MG (80.93 mg/L) cells. The viability of non-cancerous and U87MG cells exposed to extract is decreased in a dose dependent manner. It was also showed that low concentrations of extract notably increased total antioxidant capacity on non-cancerous cells. In addition, various phenolic compounds in extract were detected through high-performance liquid chromatography. The recent results encourage that extract will be able to have therapeutic potential against glioblastoma.

Vulpinic acid, a lichen metabolite, emerges as a potential drug candidate in the therapy of oxidative stress–related diseases, such as atherosclerosis

Vulpinic acid, a lichen compound, has been shown to have many beneficial effects and its medicinal value increases day by day. As in atherosclerosis, endothelial damage is the basis of many diseases. The aim of this study is to investigate the effects of vulpinic acid against oxidative stress damage induced by hydrogen peroxide (H2O2) in endothelial cells. In order to find the IC50 of H2O2 and the protective dose of vulpinic acid, methyl thiazolyldiphenyl tetrazolium bromide (MTT) assays were performed. The amount of reactive oxygen species (ROS) induced by H2O2 and the protective effects of vulpinic acid against ROS were examined by fluorometric DCF-DA kit. The effects of H2O2 and vulpinic acid on actin filaments were determined by tetramethyl rhodamine (TRITC)-phalloidin fluorescence staining. Expression of Tie2 proteins was immunocytochemically analyzed in H2O2- and vulpinic acid-treated cells. After 24 h, the IC50 was found to be 215 μM in HUVECs treated with H2O2. The most effective dose of vulpinic acid against H2O2-associated damage was found to be 15 μM. Vulpinic acid pretreatment was shown to reduce H2O2-induced ROS production significantly ( p < 0.05). It was shown that 215 μM of H2O2 caused actin fragmentation, cell shrinkage, and decrease in actin florescence intensity while vulpinic acid protected the cells from these damages. It was found that Tie2 immunoreactivity was decreased in H2O2-treated groups and vulpinic acid pretreatment reduced the expression of this protein. In conclusion, vulpinic acid decreases H2O2-induced oxidative stress and oxidative stress–related damages in HUVECs. It may be drug candidate in the therapy of atherosclerosis.