Specialized Metabolites of the Lichen Vulpicida pinastri Act as Photoprotective Agents

Abstract

The extreme resiliency of lichens to UV radiations makes them an interesting model to find new photoprotective agents acting as UV-blockers and antioxidant. In this research, using a new in vitro method designed to overcome the shortage of material associated to many studies dealing with natural products, we show that the three major compounds isolated from the lichen Vulpicida pinastri, vulpinic acid, pinastric acid and usnic acid, were UV blocker agents. Antioxidant assays evidenced superoxide anion scavenging activity. Combination of the most promising compounds against UVB and UVB radiations, usnic acid, vulpinic acid and pinastric acid, increased the photoprotective activity. At the same time, they were found not cytotoxic on keratinocyte cell lines and photostable in the UVA and UVB ranges. Thus, lichens represent an attractive source to find good candidate ingredients as photoprotective agents. Additionally, the uncommon scalemic usnic acid mixture in this Vulpicida species was proven through electronic circular dichroism calculation.

Enantioselective activity of usnic acid: a comprehensive review and future perspectives

“…)-and (-)-isomers in 35/65 ratio. The mixture of both isomers revealed moderate antioxidant activity in the superoxide radical scavenging NBT test in comparison to ascorbic acid used as a positive control, with IC 50 24 and 3 lg/mL, respectively, while no activity in DPPH test was observed, with IC 50 [ 500 lg/mL (Legouin et al 2017). The same authors also described the photoprotective potential of the mixture of enantiomers.…”

“…On the other hand, lichen taxa in which mixtures of both enantiomers were reported, namely Flavocetraria or Vulpicida, belong to the cetrarioid clade of the Parmeliaceae family. The ratio of these mixtures was determined only in a few studies (see Table 1), mostly by means of chiral HPLC separation (Kinoshita et al 1997;Smeds and Kytöviita 2010) or electronic circular dichroism (Legouin et al 2017). These are useful tools for the quantitative characterization of isomers.…”

“…Moreover, the compound was photostable after UVA irradiation, retaining its protective properties. The authors also measured the phototoxic potential of usnic acid on irradiated keratinocytes, reporting the calculated photo-irritancy factor (PIF) as 0.7, while the threshold value is established at 5 (Legouin et al 2017).…”

Carbon Consumption Patterns of Microbial Communities Associated with Peltigera Lichens from a Chilean Temperate Forest

“…Several studies have characterized the biologically active metabolites produced by lichens (e.g., antibiotic, antiviral, anti-inflammatory, analgesic, cytotoxic, etc.) [ 71 , 73 , 74 , 75 , 76 ]; however, fewer studies isolated microorganisms associated with lichens as bioresources of novel bioactive compounds with biotechnological applications [ 77 , 78 , 79 , 80 , 81 ]. Here we propose that metabolic profiling could be used as a preliminary approach to select suitable samples to isolate microorganisms with specific metabolic features.…”

A facile in vivo procedure to analyze metabolic pathways in intact lichens

“…Nevertheless, usnic acid was shown to exhibit many other beneficial properties, such as being antiviral against hepatitis C and influenza viruses (Shtro et al ., , ; Wei et al ., ), antibacterial against Mycobacterium tuberculosis (Ramos & Almeida da Silva, ; Cirillo et al ., ) and Gram‐positive bacteria including Staphylococcus aureus (Francolini et al ., ; Paudel et al ., ; Pompilio et al ., ; Tozatti et al ., ), anti‐protozoal (Sussmann et al ., ), anti‐helmintic (Araújo et al ., ), anti‐mitotic (al‐Bekairi et al ., ; Cardarelli et al ., ), anti‐inflammatory (Vijayakumar et al ., ), analgesic (Okuyama et al ., ), anti‐cancer (Yang et al ., ) and herbicidal (Romagni et al ., ). Moreover, the compound absorbs UV light making it a potential ingredient in sunscreen products (Legouin et al ., ).…”