Natural products from plants have served mankind in a wide range of applications, such as medicines, perfumes, or flavoring agents. For this reason, synthesis, regulation and function of plant-derived chemicals, as well as the evolution of metabolic diversity, has attracted researchers all around the world. In particular, vascular plants have been subject to such analyses due to prevalent characteristics such as appearance, fragrance, and ecological settings. In contrast, bryophytes, constituting the second largest group of plants in terms of species number, have been mostly overlooked in this regard, potentially due to their seemingly tiny, simple and obscure nature. However, the identification of highly interesting chemicals from bryophytes with potential for biotechnological exploitation is changing this perception. Bryophytes offer a high degree of biochemical complexity, as a consequence of their ecological and genetic diversification, which enable them to prosper in various, often very harsh habitats. The number of bioactive compounds isolated from bryophytes is growing rapidly. The rapidly increasing wealth of bryophyte genetics opens doors to functional and comparative genomics approaches, including disentangling of the biosynthesis of potentially interesting chemicals, mining for novel gene families and tracing the evolutionary history of metabolic pathways. Throughout the last decades, the moss Physcomitrella (Physcomitrium patens) has moved from being a model plant together with Marchantia polymorpha in fundamental biology into an attractive host for the production of biotechnologically relevant compounds such as biopharmaceuticals. In the future, bryophytes like the moss P. patens might also be attractive candidates for the production of novel bryophyte-derived chemicals of commercial interest. This review provides a comprehensive overview of natural product research in bryophytes from different perspectives together with biotechnological advances throughout the last decade.

Bryophytes produce rare and bioactive compounds with a broad range of therapeutic potential, and many species are reported in ethnomedicinal uses. However, only a few studies have investigated their potential as natural anti-inflammatory drug candidate compounds. The present study investigates the anti-inflammatory effects of thirty-two species of bryophytes, including mosses and liverworts, on Raw 264.7 murine macrophages stimulated with lipopolysaccharide (LPS) or recombinant human peroxiredoxin (hPrx1). The 70% ethanol extracts of bryophytes were screened for their potential to reduce the production of nitric oxide (NO), an important pro-inflammatory mediator. Among the analyzed extracts, two moss species significantly inhibited LPS-induced NO production without cytotoxic effects. The bioactive extracts of Dicranum majus and Thuidium delicatulum inhibited NO production in a concentration-dependent manner with IC₅₀ values of 1.04 and 1.54 µg/mL, respectively. The crude 70% ethanol and ethyl acetate extracts were then partitioned with different solvents in increasing order of polarity (n-hexane, diethyl ether, chloroform, ethyl acetate, and n-butanol). The fractions were screened for their inhibitory effects on NO production stimulated with LPS at 1 ng/mL or 10 ng/mL. The NO production levels were significantly affected by the fractions of decreasing polarity such as n-hexane and diethyl ether ones. Therefore, the potential of these extracts to inhibit the LPS-induced NO pathway suggests their effective properties in attenuating inflammation and could represent a perspective for the development of innovative therapeutic agents.

Mosses from the genus Polytrichum have been shown to contain rare benzonaphthoxanthenones compounds, and many of these have been reported to have important biological activities. In this study, extracts from Polytrichum formosum were analyzed in vitro for their inhibitory properties on collagenase and tyrosinase activity, two important cosmetic target enzymes involved respectively in skin aging and pigmentation. The 70% ethanol extract showed a dose-dependent inhibitory effect against collagenase (IC₅₀ = 4.65 mg/mL). The methanol extract showed a mild inhibitory effect of 44% against tyrosinase at 5.33 mg/mL. Both extracts were investigated to find the constituents having a specific affinity to the enzyme targets collagenase and tyrosinase. The known compounds ohioensin A (1), ohioensin C (3), and communin B (4), together with nor-ohioensin D (2), a new benzonaphthoxanthenone, were isolated from P. formosum. Their structures were determined by mass spectrometry and NMR spectroscopy. Compounds 1 (IC₅₀ = 71.99 µM) and 2 (IC₅₀ = 167.33 µM) showed inhibitory activity against collagenase. Compound 1 also exhibited inhibition of 30% against tyrosinase activity at 200 µM. The binding mode of the active compounds was theoretically generated by an in-silico approach against the 3D structures of collagenase and tyrosinase. These current results present the potential application from the moss P. formosum as a new natural source of collagenase and tyrosinase inhibitors.

Bazzania trilobata (L.) Gray is a leafy liverwort from the family of Lepidoziaceae, well known for its antifungal properties. In this study, the 70% ethanol and methanol extracts of B. trilobata were investigated for new in vitro biological activities of cosmetic interest. The results showed that the total phenol content, the DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging activity, and the anti-collagenase activity of the 70% ethanol extract were higher than for methanol. The methanol extract showed mild tyrosinase inhibitory activity and antimicrobial properties towards the Gram-positive bacteria Enterococcus faecalis. Lignans, coumarins, and bis-bibenzyls were the major classes of phenolic constituents tentatively identified in both extracts. In addition, a known drimenyl caffeate was identified in B. trilobata and its structure was confirmed by NMR spectroscopy. These results suggest that extracts from B. trilobata could be exploited as an interesting new source of natural active ingredients for cosmetic applications. Keywords Antioxidant Antimicrobial Bazzania trilobata Collagenase inhibitory activity Drimenyl caffeate Tyrosinase inhibitory activity

Bazzania trilobata (L.) Gray is a leafy liverwort from the family of Lepidoziaceae, well known for its antifungal properties. In this study, the 70% ethanol and methanol extracts of B. trilobata were investigated for new in vitro biological activities of cosmetic interest. The results showed that the total phenol content, the DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging activity, and the anti-collagenase activity of the 70% ethanol extract were higher than for methanol. The methanol extract showed mild tyrosinase inhibitory activity and antimicrobial properties towards the Gram-positive bacteria Enterococcus faecalis. Lignans, coumarins, and bis-bibenzyls were the major classes of phenolic constituents tentatively identified in both extracts. In addition, a known drimenyl caffeate was identified in B. trilobata and its structure was confirmed by NMR spectroscopy. These results suggest that extracts from B. trilobata could be exploited as an interesting new source of natural active ingredients for cosmetic applications. Keywords Antioxidant Antimicrobial Bazzania trilobata Collagenase inhibitory activity Drimenyl caffeate Tyrosinase inhibitory activity