International Journal of Medicinal Mushrooms, 19(11):1023–1027 (2017) Profiles of Little-Known Medicinal Polypores: Earliella scabrosa (Agaricomycetes) Ivan V. Zmitrovich,1,* Oleg N. Ezhov,2 Kiran R. Ranadive,3 & Solomon P. Wasser4 1 Laboratory of Systematics and Geography of the Fungi of the Komarov Botanical Institute of the Russian Academy of Sciences, St. Petersburg, Russia; 2N. Laverov Federal Center for Integrated Arctic Research, Arkhangelsk, Russia; 3Waghire College, Saswad, Tal-Purandar, District-Pune, Maharashtra, India; 4Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences and Institute of Evolution, University of Haifa, Mount Carmel, Haifa, Israel *Address all correspondence to: Ivan V. Zmitrovich, Laboratory of Systematics and Geography of the Fungi of the Komarov Botanical Institute of the Russian Academy of Sciences, 2 Professor Popov St., St. Petersburg 197376, Russia; IZmitrovich@binran.ru or iv_zmitrovich@mail.ru ABSTRACT: The purpose of this study was to comprehensively characterize a little-known polypore that has recently been found to possess anticancer activity and thus can also be used in targeted cancer therapy. Earliella scabrosa is a polypore with pantropical distribution and can be found in rainforests in both the Eastern and Western Hemispheres. Some reports have described its antioxidant properties and free radical scavenging ability. Moreover, isocoumarin, which has been successfully used in targeted cancer therapy, was found in extracts of this fungus. We recommend further research of E. scabrosa so that more details of its health benefits could be used in mycotherapy. KEY WORDS: Earliella, Earliella scabrosa, distribution, isocoumarin, medicinal mushrooms, medicinal polypores, morphology, radical scavenging fungal material, target therapy ABBREVIATIONS: NM-3, 2-(8-hydroxy-6-methoxy-1-oxo-1h-2-benzopyran-3-yl)propionic acid; uPA, urokinase-type plasminogen activator I. INTRODUCTION The purpose of this study was to comprehensively characterize a little-known polypore that has recently been found to possess anticancer activity and to contain substances that can be used in targeted cancer therapy. Earliella scabrosa (Pers.) Gilb. & Ryvarden (Basidiomycota, Agaricomycetes, Polyporales, Polyporaceae) is a polypore with pantropical distribution and can be found in rainforests of both the Eastern and Western Hemispheres.1 Like many tropical polypores, this fungus is characterized by skeletal hyphae with a strong, thick secondary wall that contains few β-glucans.2 This characteristic is why interest in this species is rather low in fungal pharmacology. On the other hand, some reports have described its antioxidant properties3 and free radical-scavenging ability.4 Furthermore, isocoumarin was found in extracts of the fungus in question.5 This substance, which has been isolated from other plant material, is 1521-9437/17/$35.00 © 2017 Begell House, Inc. www.begellhouse.com successfully used in targeted cancer therapy. Thus further investigation into E. scabrosa is recommended. The aim of our study was to comprehensively characterize E. scabrosa. Our intention is to increase knowledge of this species within the mycotherapy community. II. MATERIALS AND METHODS Macroscopic descriptions are based on studies of fresh and dried specimens. Microscopic preparations from dried material were mounted in Melzer solution, 10% ammonium Congo Red, and 5% aqueous KOH solution, and viewed using a LOMO Micmed-6 light microscope. The hyphal system was revealed and described according to an updated technique.1,2 The size of mature spores was determined by measuring 30 spores in distilled water and Melzer solution. The specimens examined have been deposited in the Mycological Herbarium at the Komarov Botanical Institute of the Russian Academy of Sciences. 1023 Zmitrovich et al. 1024 III. RESULTS AND DISCUSSION A. Characterization of E. scabrosa 1. Taxonomy E. scabrosa is a species that belongs to the class Agaricomycetes, order Polyporales. Within Polyporales, this fungus takes its place near Lentinus, Hexagonia, and Daedaleopsis.6 According to Zmitrovich,2 within Polyporaceae, E. scabrosa is classified within the tribe Lentineae of the Polyporoideae subfamily. The species Polyporus scabrosus was described by Persoon in a book by GaudichaudBaupre7 published in 1827. Since then, this species has been described again and again under various names, as shown in Table 1. Gilbertson and Ryvarden8 created the combination E. scabrosa in 1985, although Murrill9 presented this mushroom as E. cubensis. 2. Morphology Basidiomata are annual or perennial, of corioloid habit, with a prominent decurrent part, up to resupinate. Pilei are reflexed up to 5(7) cm, are 2.5–8 cm wide, are often confluent, and take various shapes, but they are more or less applanate, up to 1(2.5) cm thick, and of coriaceous consistency. The upper side is glabrous; obscurely concentrically zonate; first ivory to cream, then covered by a reddish crust beginning from the base; scrupose; and wrinkled. The margin is sharp, dull, or bolster-like; ivory to cream; and sterile. The hymenophore is porioid, not stratified, with tubes up to 6 mm long. Pores are round, sinuous to semidedaloid (especially on sloping parts of the basidiocarp), with 2 or 3 per millimeter, but individual elongated pores reach 6 mm long. The pore surface is white to cork-colored. The context is white, ivory to cream, tough and coriaceous to suberose, and 2–20 mm thick, in a section with a distinct dark line (Fig. 1). The hyphal system is dimitic. Generative hyphae measure 1.5‒4.5 µm and are clamped and thin-walled. Skeletal hyphae are 2.5‒7 µm wide, TABLE 1: Names That Are Synonymous with Earliella scabrosa Name Year Polyporus scabrosus Pers. P. fuscobadius Pers. P. corrugatus Pers. Daedalea sanguinea Klotzsch P. persoonii Mont. P. indecorus Jungh. P. venulosus Jungh. D. microsinuosa Klotzsch et Berk. P. tostus Berk. Hexagonia cruenta Mont. P. tegularis Lév. Trametes hookeri Berk. D. emodensis Berk. T. versiformis Berk. et Broome H. picta Berk. P. aruensis Berk. T. moselei Berk. Polystictus parishii Berk. ex Cooke T. nitida Pat. D. conchata Bres. D. andamani Berk. ex Cooke P. rufocinerescens Henn. Earliella cubensis Murrill Favolus subrigidus Murrill T. zimmermanii Bres. 1827 1827 1827 1833 1834 1838 1838 1839 1844 1845 1846 1854 1854 1872 1878 1878 1878 1886 1890 1890 1891 1899 1905 1908 1920 hyaline, and thick-walled to subsolid, with a sympodial branching pattern. Many pyramidal crystals can be found in tramal and contextual tissues. No cystidia are found. Yellow-brown clavate sclerids (5‒8 × 20–40 µm) form a dense glued layer within a crust region. Basidia clavate (15‒22 × 5–7.5 μm) are 4-spored, with a basal clamp. Basidiospores ([7]9–12.5 × 3‒4.3 µm) are ellipsoid to cylindrical, tapering at both ends, and are smooth, thin-walled, acyanophilous, and inamyloid (Fig. 2). E. scabrosa grows on fallen logs, stumps, and timber of hardwoods, causing white rot.10 International Journal of Medicinal Mushrooms Medicinal Profiles of Earliella scabrosa 1025 FIG. 1: Details of the macromorphology of Earliella scabrosa: a modal effused-reflexed morphotype, Belize, coll. O. N. Ezhov (LE 269709) (a); a resupinate morphotype, Cuba, Coll. O. N. Ezhov (LE 269618) (b); a pileate rozette-like morphotype, Vietnam, coll. A. A. Polilov (LE 269643) (c); and the typical shape of the hymenophore (LE 269698) (d). Scale bar = 1 cm 3. Distribution E. scabrosa is found in Africa (Liberia, Cameroon, Tanzania, Mayotte), Asia (India, Vietnam, Thailand, China, Taiwan, Russia [Far East], Japan, Philippines, Singapore, Malaysia), Oceania (Papua New Guinea, Fiji, Tonga), North America (United States [Hawaii], Mexico), Central America (Costa Rica, Panama, Jamaica, Dominican Republic, Saint Vincent, and the Grenadines), and South America (Venezuela, Suriname, Brazil, Chile).11–16 Volume 19, Issue 11, 2017 Everywhere the species gravitates toward open places: on roadsides, felled trees, and clear-cut areas.17 B. Chemical Composition Teles et al.5 fractionated an aqueous extract of E. scabrosa using high-performance liquid chromatography. They identified 2 purine bases and 2 polycyclic polysteroids in this fungal extract; moreover, isocoumarin and lipodepsipeptide have been recognized (Fig. 3). 1026 Zmitrovich et al. FIG. 2: Key elements of the micromorphology of Earliella scabrosa (LE 296643): fibroid fragments of skeletal hyphae with capillary lumen and a coiled or straight outline (a); a sympodially branched fragment of skeletal hyphae (b); melanized and hyaline sclerids (c); and basidiospores (d). Scale bar = 10 μm. C. Perspectives in Cancer Therapy With regard to cancer therapy, the fungus E. scabrosa seems to be interesting because of its radical scavenging activity and as a producer of isocoumarin. The urokinase-type plasminogen activator (uPA) is known to play a major role in extracellular proteolytic events associated with tumor cell growth, migration, and angiogenesis. Consequently, uPA is an attractive target for the development of small-molecule active site inhibitors. Heynekamp et al.18 have shown that potent uncharged inhibitors of uPA could be developed based on an isocoumarin scaffold. Also, as shown by Yin et al.,19 2-(8-hydroxy6-methoxy-1-oxo-1H-2-benzopyran-3-yl) propionic acid, an isocoumarin derivative, had a direct effect on human carcinoma cells. The results demonstrate that NM-3 treatment is associated with the generation of reactive oxygen species and lower clonogenic survival. In concert with these findings, exposure to NM-3 was associated with increases in expression of the p53 tumor suppressor. In human MCF-7 and ZR-75-1 breast cancer cells, NM-3 induced the p21 cyclin-dependent kinase inhibitor, cell cycle arrest at the G1/S phase, and necrotic cell death. Moreover, human PA-1 ovarian carcinoma and HeLa cervical carcinoma cells responded to NM-3 through the FIG. 3: Chemical composition of the aqueous extract of Earliella scabrosa according to Teles et al.5: 1 and 2, purine bases; 3 and 4, polycyclic polysteroids; 5, isocoumarin; 6, lipodepsipeptide International Journal of Medicinal Mushrooms Medicinal Profiles of Earliella scabrosa induction of apoptosis by a reactive oxygen species–dependent mechanism. These findings show that NM-3 has direct effects on carcinoma cells at clinically achievable concentrations and that this agent could be effective in targeting both the tumor and its vasculature. Concerning the ability of E. scabrosa in the scavenging of free radicals and active oxygen forms, it is necessary to note that such an activity is important in tumor prevention because it contributes to genome stability, but this can lead to tumor progression through the creation of advantages of cancer clones, which have lower catabolic potential.20 Therefore, in target cancer therapy, isocoumarin must be isolated from radical scavenging substances. 1027 6. 7. 8. 9. 10. ACKNOWLEDGMENTS 11. The authors are grateful to Professor J.G. Vaidya, Dr. J.R. Sharma, Dr. Gurpaul Singh Dhingra, Harpreet Kaur, and Dr. Mohammad Hossein Hakimi Meibodi for presenting sources on the distribution of E. scabrosa. The work of I.V. Zmitrovich was carried out in frameworks of the State Task of the V.L. Komarov Botanical Institute of the Russian Academy of Sciences (N 01201255603). 12. REFERENCES 1. 2. 3. 4. 5. Zmitrovich IV, Wasser SP, Ezhov ON. A survey of species of genus Trametes Fr. 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