Tylopilus felleus (Bull.) P. Karst., the bitter bolete.
Boletus alutarius Fr.
Boletus alutarius Rostk.
Boletus felleus Bull.
Tylopilus alutarius (Fr.) Rea
Tylopilus felleus var. alutarius (Fr.) P. Karst.
Tylopilus felleus (Bull.) P. Karst., Revue mycol.
Tylopilus felleus var. minor (Coker & Beers) Pilát & Dermek
Tylopilus felleus var. uliginosus A.H. Sm. & Thiers
Cap: 5-15 cm; convex to broadly convex or nearly flat in age; dry; smooth, unpolished; sometimes becoming cracked; brown to tan, usually with cinnamon shades, becoming paler with age. Pore surface salmon to flesh-colored; sometimes bruising brownish; pores circular, 1-2 per mm; tubes to 2 cm.
Stem: 4-20 cm long; 1-3 cm thick (above the base); often curved; club-shaped and bulbous; pale above, concolorous with cap downward; strongly reticulate, at least over upper third; sometimes with olive stains in age.
Flesh: thick and white; unchanging or staining pinkish.
Spore print: flesh colored to clay-pink.
Spores: 11-17 x 3-5 µm; spindle-shaped to elliptical; smooth.
Habitat: coniferous and deciduous woodland. Season late summer to autumn. Solitary, or sometimes small groups.
Edibility: inedible due to its extremely bitter taste.
Chemical reactions: cap surface orange to reddish orange with KOH or ammonia, olive with iron salts; flesh greenish yellow with KOH, pale yellow (with a bluish zone) with ammonia; grayish green with iron salts. Siderophilous granulation is a characteristic of this species.
Details about the distinguishing microscopic characteristics of this and other Tylopilus species are given in Wolfe (1991).
Polysaccharides extracted from the mycelial culture of T. felleus and administered intraperitoneally into white mice at a dosage of 300 mg/kg inhibited the growth of Sarcoma 180 and Ehrlich solid cancers by 100% (Ohtsuka et al., 1973).
Another mouse study evaluated the antitumor activity of tylopilan, a β-(1→3) (1→6) linked glucan isolated from fruit bodies in combination with a Propionibacterium acnes preparation (known to be immunogenic). A single injection of tylopilan (25 or 50 µg per mouse) was sufficient to extend the mean survival time of mice injected with tumor cells from 17.5 to 22.8 days. Tylopilan injected in conjunction with the immunostimulative Propionibacterium acnes preparation prolonged significantly MST in comparison to control mice as well as to tylopilan alone treated mice suggesting that the immune stimulation enhances the antitumor effect of tylopilan. Additionally, tylopilan showed cytotoxic activity towards 180-TG Crocker tumor cells in vitro at a variety of concentrations ranging from 37.5 to 300 µg/ml (Grzbek et al., 1994).
T. felleus lyophilized preparation tested in the carrageenin-induced oedema test in rats, exhibit a significant inhibition of inflammation at all doses above 50 mg/kg (subcutaneous) while oral administration produced no significant results (Kohlmunzer et al., 1977)
Grzybek J, Zgorniaknowosielska I, Kasprowicz A, Zawilinska B, Kohlmunzer S.
Antitumor activity of a fungal glucan tylopilan and Propionibacterium acnes preparation.
Acta Societatis Botanicorum Poloniae. 1994 63(3-4):293-8.
Kohlmunzer S, Grzybek J, Molik-Wegiel J.
Investigations on the biological activity of extracts of Tylopilus felleus (Bull. ex Fr.) P Karst. by means of mycological tests.
Pol J Pharmacol Pharm. 1975 27(1):95-9.
Ohtsuka S, Ueno S, Yoshikumi C, Hirose F, Ohmura Y, Wada T, Fujii T, Takahashi E.
Polysaccharides having an anticarcinogenic effect and a method of producing them from species of Basidiomycetes.
UK Patent 1331513, 26 September 1973.