Endolichenic Fungus Research Articles

Identification of Novel Bioactive Compounds, Neurosporalol 1 and 2 from an Endolichenic Fungus, Neurospora ugadawe Inhabited in the Lichen Host, Graphis tsunodae Zahlbr. from Mangrove Ecosystem in Puttalam Lagoon, Sri Lanka

Endolichenic fungi (ELF) have been recognized as a promising source of bioactive secondary metabolites. Sri Lanka, a biodiversity hotspot, harbours a remarkable diversity in mangrove ecosystems. In the present study, endolichenic fungi obtained from mangrove lichens of Puttalam lagoon were studied for their secondary metabolites. An endolichenic fungus, Neurospora ugadawe, isolated from the lichen host Graphis tsunodae Zahlbr. was identified up to the species level. Secondary metabolites of N. ugadawe were extracted into ethyl acetate and crude extract showed promising antioxidant and anti-inflammatory activities. Bioassay guided separation on silica gel column chromatography and preparative TLC were performed to isolate the bioactive pure compounds. Two novel bioactive pure compounds were identified as Neurosporalol 1 and Neurosporalol 2. Neurosporalol 1 showed the highest antioxidant activity compared with the positive control BHT. Further, this compound showed very low anti-inflammatory activity compared to that of the positive control aspirin. Neurosporalol 2 showed comparable antioxidant and moderate anti-inflammatory activities.

New phenol and chromone derivatives from the endolichenic fungus Daldinia species and their antiviral activities.

Three new phenolic metabolites, daldispols A–C (1–3), two new chromone derivatives, (5R,7R)-5,7-dihydroxy-2-methyl-5,6,7,8-tetrahydro-4H-chromen-4-one (9) and (5R,7R)-5,7-dihydroxy-2-propyl-5,6,7,8-tetrahydro-4H-chromen-4-one (10), together with five known phenolic compounds (4–8) and two known chromone compounds (11 and 12) were isolated from the endolichenic fungus Daldinia sp. CPCC 400770. Their structures were elucidated on the basis of spectroscopic methods, electronic circular dichroism (ECD), and comparison with reported data. Compounds 1, 3, 4, 9, and 11 exhibited significant anti-influenza A virus (IAV) activities with IC50 values of 12.7, 6.4, 12.5, 16.1, and 9.0 μM, respectively, and compound 8 displayed significant anti-ZIKV activity with inhibitory ratio of 42.7% at 10 μM. The results demonstrated that the fungus Daldinia sp. CPCC 400770 might be a rich source for discovering anti-IAV secondary metabolites as potential novel leading compounds.

Antioxidant activities of fungi inhabiting Ramalina peruviana: insights on the role of endolichenic fungi in the lichen symbiosis

Antioxidant activities of fungi inhabiting Ramalina peruviana: insights on the role of endolichenic fungi in the lichen symbiosis

A new alkanol from the endolichenic fungus Daldinia childiae

AbstractOne new alkanol, 2,4,5‐heptanetriol(1), together with four compounds, 6‐heptene‐2,4,5‐triol (2), rel‐(1S, 4S, 5R, 7R, 10R)‐10‐desmethyl‐1‐methyl‐11‐eudesmene (3), 2,3‐dihydro‐5‐hydroxy‐2‐methyl‐4H‐1‐benzopyran‐4‐one (4), (−)‐regiolone (5) were isolated from the ethyl acetate extract of rice solid‐substrate cultures of endolichenic fungus Daldinia childiae for the first time. Compounds 1, 2, and 3 were separated firstly from the genus Daldinia. Their structures were elucidated by spectral data and compound 3 exhibited α‐amylase inhibitory activity.

A secondary metabolite with in vitro radical scavenging activity from endolichenic fungus Daldinia eschscholzii found in lichen, Parmotrema sp. in Sri Lanka

Endolichenic fungi, an unexplored group of microorganisms, are a promising source of bioactive compounds. Secondary metabolites were isolated from the chloroform fraction of crude ethyl acetate extract of endolichenic fungus Daldinia eschscholzii inhabiting the lichen, Parmotrema sp. in Sri Lanka. Two pure compounds, 1 and 2 were isolated and the structures were identified using 1H-, 13C-, 2D- nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) data. Compound 1 did not show any radical scavenging activity in DPPH assay. Compound 2, identified as 8-methoxynaphthalen-1-ol showed strong radical scavenging ability in the DPPH assay with a half maximal inhibitory concentration (IC50) of 10.2 ± 5.8 µg/ mL. The activity of compound 2 was higher than that of the standard, butylated hydroxy toluene (BHT).

A Novel Cytotoxic Compound From the Endolichenic Fungus, Xylaria psidii Inhabiting the Lichen, Amandinea medusulina:

The lichen host, Amandinea medusulina, collected from mangrove habitats in Sri Lanka, and its associated endolichenic fungi were isolated and identified by rDNA-ITS sequence analysis and morphologi...

A Novel Cytotoxic Compound From the Endolichenic Fungus, Xylaria psidii Inhabiting the Lichen, Amandinea medusulina

The lichen host, Amandinea medusulina, collected from mangrove habitats in Sri Lanka, and its associated endolichenic fungi were isolated and identified by rDNA-ITS sequence analysis and morphological features. One of the fungal strains frequently isolated from the lichen thalli was identified as Xylaria psidii. This study aimed at the isolation and identification of the cytotoxic compounds present in this fungus. Secondary metabolites of X. psidii were first extracted into ethyl acetate and subsequently subjected to bioassay-guided fractionation to isolate the bioactive compounds. Sulforhodamine B assay against a lung cancer (NCI-H292) cell line was used to determine the differential cytotoxic activity. Bioassay-guided fractionation led to the isolation of an active compound, SS/02/29/08, showing moderate cytotoxicity (IC50 = 27.2 µg/mL). Its structure was elucidated by IR, 1D- and 2D-NMR, and 13C-NMR spectrophotometry and MS, in combination with HRMS, 13C NMR, HSQC, HMBC, and DQF-COSY. The structure of SS/02/29/08 was determined as ( Z)-3-{(3-acetyl-2-hydroxyphenyl)diazenyl}-2,4-dihydroxybenzaldehyde and identified as a new compound. This novel compound has promising differential cytotoxic activity against human lung cancer cell line (NCI-H292).

Cytotoxic Heptaketides from the Endolichenic Fungus Ulospora bilgramii

Eleven new metabolites including nine heptaketides, ulosporin A-G (1a-7b), one diphenyl compound, ulophenol (8), and one spirobisnaphthalene, palmarumycin P5 (9), were isolated from the endolichenic fungus Ulospora bilgramii, which inhabits the lichen Umbilicaria sp. The structures of these compounds were elucidated based on comprehensive analysis of their spectroscopic, electronic circular dichroism (ECD), and single-crystal X-ray diffraction data. Ulosporin G (7) inhibited the growth of the human cancer cell lines A549, MCF-7, and KB with IC50 values of 1.3, 1.3, and 3.0 μM, respectively. Additionally, it induced A549 cell apoptosis through G0/G1 cell cycle arrest caused by DNA damage.

Diversity and Distribution Patterns of Endolichenic Fungi in Jeju Island, South Korea

Lichens are symbiotic organisms containing diverse microorganisms. Endolichenic fungi (ELF) are one of the inhabitants living in lichen thalli, and have potential ecological and industrial applications due to their various secondary metabolites. As the function of endophytic fungi on the plant ecology and ecosystem sustainability, ELF may have an influence on the lichen diversity and the ecosystem, functioning similarly to the influence of endophytic fungi on plant ecology and ecosystem sustainability, which suggests the importance of understanding the diversity and community pattern of ELF. In this study, we investigated the diversity and the factors influencing the community structure of ELF in Jeju Island, South Korea by analyzing 619 fungal isolates from 79 lichen samples in Jeju Island. A total of 112 ELF species was identified and the most common species belonged to Xylariales in Sordariomycetes. The richness and community structure of ELF were significantly influenced by the host taxonomy, together with the photobiont types and environmental factors. Our results suggest that various lichen species in more diverse environments need to be analyzed to expand our knowledge of the diversity and ecology of ELF.

Talarolactone A, an Isocoumarin Derivative Fused with Dihydrothiophene with Selective Antimigratory Activity from the Endolichenic Fungus Talaromyces sp.

A 3,4-dihydroisocoumarin derivative fused with dihydrothiophene, talarolactone A (1), and two known compounds, terreusinone (2) and 4,6-dihydroxy-5-methylphthalide (3), were isolated from Talaromyces sp. associated with Xanthoparmelia angustiphylla. The structure of 1 was deduced from extensive spectroscopic data, electronic circular dichroism calculations, and X-ray diffraction analyses. A plausible biosynthetic pathway of 1 was further proposed. Compound 1 showed selective antimigratory activity in a wound-healing assay without appreciable cytotoxic activity.

(±)-Ulodione A, a pair of unprecedented cyclopentanones from Ulospora bilgramii

Two novel enantiomers named (R)-ulodione A (1a) and (S)-ulodione A (1b) possessing a new 5/6–5 spiro skeleton and a related metabolite ulodione B (2) were isolated from the endolichenic fungus Ulospora bilgramii. Enantiomeric separation was achieved by HPLC on a chiral column. The structures and absolute configurations of ulodione A were elucidated by means of 1D and 2D NMR spectra, high-resolution electrospray ionization mass spectrometry (HRESIMS), X-ray diffraction (XRD), and electronic circular dichroism (ECD). The possible biosynthetic pathway for ulodione A was also postulated. Compounds 1a and 1b showed butyrylcholinesterase (BuChE) inhibitory activities, with IC50 values of 9.0 ± 0.1 and 9.3 ± 0.2 μM, respectively.

Endolichenic fungi: A hidden source of bioactive metabolites

Lichens are synergetic organisms composed of a mycobiont in relationship with one or more photosynthetic partners (photobiont). These organisms grow on various substrates and sometimes under extreme ecological environments. A different group of non-obligate micro-fungi also resides inside the internal tissues of the lichen thalli without causing any harm to them. These microfungi are called as endolichenic fungi (ELF). Among various natural alternatives for the bioactive molecules, ELF are emerging as a source of metabolites of different chemical structural classes including alkaloids, quinones, furanones, pyrones, benzopyranoids, xanthones, terpenes, steroids, peptides and acyclic compounds. These compounds exhibited various biological activities, viz., anticancer, antiviral, antibacterial, antifungal and anti-Alzheimer's etc. This review aims to highlight about ninety-nine novel compounds out of the total 172 reported metabolites isolated during the period from 2008 to 2019 (up to March 2019) from ELF. An overview of the unexplored perspective of ELF as a source of novel natural bioactive products is provided. Some of the procedures for activation of the silent biosynthetic ‘gene clusters’ responsible for their production are also discussed.

Sarcosenones A-C, highly oxygenated pimarane diterpenoids from an endolichenic fungus Sarcosomataceae sp.

Three new highly oxygenated pimarane diterpenoids, sarcosenones A–C (1–3), and the known 9α-hydroxy-1,8(14),15-isopimaratrien-3,7,11-trione (4), were isolated from cultures of an endolichenic fungus Sarcosomataceae sp. Their structures were elucidated based on NMR spectroscopic data and electronic circular dichroism (ECD) calculations. Compound 1 showed moderate cytotoxicity against a small panel of four human tumor cell lines, with IC50 values of 7.5–26.4 μM.

The diversity of endolichenic fungi – A review

The diversity of endolichenic fungi – A review

Endolichenic fungus, Aspergillus quandricinctus of Usnea longissima inhibits quorum sensing and biofilm formation of Pseudomonas aeruginosa PAO1

Lichens are composite organisms, comprising of a fungus (mycobiont) and a blue-green alga (photobiont). Along with the mycobiont, numerous non-obligate microfungi live in lichen thalli. These microfungi are called endolichenic fungi (ELF). In recent years, the ELF are emerging as promising natural sources because of their capability to exert unique drug molecules. The current study aimed to isolate the ELF from the lichen, Usnea longissima Ach., to control of biofilm formation and quorum sensing phenomenon in Pseudomonas aeruginosa PAO1, an opportunistic multidrug resistance pathogen that uses quorum sensing network to produce an array of pathogenic agents. Therefore, inhibiting quorum sensing to manage the infection caused by PAO1 could be the paramount alternative approach to conventional antibiotics. The isolated ELF was identified by amplifying the long subunit region of the fungal genome. The extracted metabolites of ELF (MELE) using the acetone solvent was further investigated for anti-quorum sensing activity using the biomarker strain Chromobacterium violaceum 12472 which exerts violacein pigment via the AHL mediated quorum sensing signalling. Moreover, the effect of MELE was also evaluated on the production of virulence factors and biofilm formation of P. aeruginosa PAO1. The molecular identification revealed that ELF (accession number MN171299) exhibited 100% similarity with Aspergillus quandricinctus strain CBS 135.52. The MELE showed significant anti-quorum sensing activity at the concentration of 4 mg/mL without affecting the bacterial cell viability of P. aeruginosa PAO1. The MELE diminished the production of virulence factors, including pyocyanin, protease, elastase, rhamnolipids, and extracellular polysaccharides of P. aeruginosa PAO1 in a concentration-dependent manner. The MELE also disturbed biofilm formation of P. aeruginosa PAO1. The 3-D analysis of biofilm architecture showed that the thickness and surface area covered by microcolonies was decreased as the concentration of MELE was increased. The GC-MS analysis of MELE exhibited that organic acids and fatty acids are major constituents of the MELE. The present study reports first time that the ELF, A. quandricinctus possesses potential to inhibit quorum sensing and biofilm formation of P. aeruginosa and can be further exploited for hospital and healthcare facilities.

Chrysoviruses Inhabited Symbiotic Fungi of Lichens.

A lichen body is formed most often from green alga cells trapped in a net of ascomycetous fungi and accompanied by endolichenic or parasitic fungi, other algae, and symbiotic or free-living bacteria. The lichen’s microcosmos is inhabited by mites, insects, and other animals for which the lichen is a source of food or a place to live. Novel, four-segmented dsRNA viruses were detected in saxicolous Chrysothrix chlorina and Lepraria incana lichens. Comparison of encoded genome proteins revealed classification of the viruses to the genus Alphachrysovirus and a relationship to chrysoviruses from filamentous ascomycetous fungi. We propose the names Chrysothrix chrysovirus 1 (CcCV1) and Lepraria chrysovirus 1 (LiCV1) as acronyms for these viruses. Surprisingly, observation of Chrysothrix chlorina hybridization with fluorescent-labelled virus probe by confocal microscope revealed that the CcCV1 virus is not present in the lichen body-forming fungus but in accompanying endolichenic Penicillium citreosulfuratum fungus. These are the first descriptions of mycoviruses from a lichen environment.

Endolichenic fungal diversity associated with some lichens of the Western Ghats

A total of 389 strains of fungi belonging to 38 species were isolated from 10 lichen species of the Western Ghats, southern India. All the lichens screened, irrespective of their growth forms or location, harboured endolichenic fungi. Most of the fungi belonged to the Ascomycotina. Chaetomium sp. 1, Hypoxylon investiens, Nemania bipapillata, Nodulisporium sp., Paecilomyces sp., and Sporormiella intermedia were the most common ones and were present in 5 or more lichen species. Of the 28 sporulating fungi, 7 belonged to Xylariales, and their total colonization frequency in all the lichens was also high. This observation further substantiates the high ecological amplitude of Xylariales, possibly due to overlapping ecological niches and their ability to inhibit co-occurring endolichenic fungi.

Polyketides from the endolichenic fungus Eupenicillium javanicum and their anti-inflammatory activities

Seven undescribed polyketides javanicols A−E, 5-epi-citreoviridin and 5-epi-isocitreoviridin, together with five known compounds, were isolated from the endolichenic fungus Eupenicillium javanicum. The structures of these polyketides were determined by means of extensive spectroscopic analyses, electronic circular dichroism (ECD) calculations and gauge-independent atomic orbital (GIAO) NMR shift calculations. These compounds were evaluated for potential anti-inflammatory activity against LPS-activated RAW 264.7 cells. Javanicol E and (+)-terrein displayed moderate inhibitory effects on NO production, with IC50 values of 17.00 and 13.46 μM, respectively.

Where are they hiding? Testing the body snatchers hypothesis in pyrophilous fungi

Abstract Pyrophilous fungi produce sporocarps after a fire but little is known about their ecology prior to or after a fire event. Recently, the body snatchers hypothesis was proposed that suggests some post-fire fungi form endophytic and/or endolichenic relationships with plants and lichens. To test the body snatchers hypothesis, bryophyte, lichen, club moss, and soil samples were collected from unburned and mixed-intensity burned areas 1–2 y after a 2016 wildfire in the Great Smoky Mountains National Park, and from unburned areas in four states outside the park. Samples were examined for the presence of pyrophilous fungi occurring as endophytes or in lichens using culture-dependent and culture-independent techniques. Culture-dependent methods isolated Pholiota highlandensis, a known pyrophilous fungus, from five bryophyte samples. Culture-independent methods identified 22 pyrophilous taxa from bryophyte, club moss, lichen, and soil samples across a range of geographical localities. The ‘body snatchers’ hypothesis is supported since many bryophyte, lichen, and club moss samples contained pyrophilous taxa suggesting that these fungi occur as endophytes and/or endolichenic fungi until a fire event triggers them to produce sporocarps.

Morphological and Molecular Characterization of Three Endolichenic Isolates of Xylaria (Xylariaceae), from Cladonia curta Ahti & Marcelli (Cladoniaceae).

Endophyte biology is a branch of science that contributes to the understanding of the diversity and ecology of microorganisms that live inside plants, fungi, and lichen. Considering that the diversity of endolichenic fungi is little explored, and its phylogenetic relationship with other lifestyles (endophytism and saprotrophism) is still to be explored in detail, this paper presents data on axenic cultures and phylogenetic relationships of three endolichenic fungi, isolated in laboratory. Cladonia curta Ahti & Marcelli, a species of lichen described in Brazil, is distributed at three sites in the Southeast of the country, in mesophilous forests and the Cerrado. Initial hyphal growth of Xylaria spp. on C. curta podetia started four days after inoculation and continued for the next 13 days until the hyphae completely covered the podetia. Stromata formation and differentiation was observed, occurring approximately after one year of isolation and consecutive subculture of lineages. Phylogenetic analyses indicate lineages of endolichenic fungi in the genus Xylaria, even as the morphological characteristics of the colonies and anamorphous stromata confirm this classification. Our preliminary results provide evidence that these endolichenic fungi are closely related to endophytic fungi, suggesting that the associations are not purely incidental. Further studies, especially phylogenetic analyses using robust multi-locus datasets, are needed to accept or reject the hypothesis that endolichenic fungi isolated from Xylaria spp. and X. berteri are conspecific.