The Japanese mushroom Lactarius flavidulus S. Imai.
Ki hatsu take (Japanese)
As far as I can determine, this species has only been reported from Japan, and descriptive information is sketchy. Nagasawa (1998) suggests that a more correct name is L. tottoriensis.
Spores: 8-9.2 x 6-7 µm (see a photo here)
Three novel geranylphenols, flavidulols A, B and C (structures shown below), were isolated from Lactarius flavidulus while screening for new inhibitors of proliferation of mouse lymphocytes (Takahashi et al., 1988). The original structures determined for these compounds were later revised based on NMR analysis (Takahashi et al., 1993). This paper also reported the isolation of flavidulol D, also shown below.
The IC50 values for the concanavalin A-induced proliferation of mouse lymphocytes were determined to be 8.9 µg/ml, 4.9 µg/ml and 36.6 µg/ml, respectively, while against lipopolysaccharide-stimulated proliferation, the corresponding IC50 values were 6.7, 3.9 and 28.3 μg/ml (Fujimoto et al., 1993)
Antimicrobial and antifungal activity
Using the serial two-fold dilution method, flavidulol A demonstrated antimicrobial activity against various pathogenic organisms (minimum inhibitory concentrations in µg/ml given in parentheses): Staphylococcus aureus (6.2), Bacillus subtilis (6.2), Escherichia coli (>100), Candida albicans (25), Trichophyton rubrum (6.2), and T. mentagrophytes (6.2) (Takahashi et al., 1988). The latter two organisms are fungi responsible for various skin ailments such as athletes foot, jock itch, and ringworm.
Polysaccharides extracted from the mycelial culture of L. flavidulus 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).
Lorenzen K, Anke T, Konetschny-Rapp S, Scheuer W.
5-hydroxy-3-vinyl-2(5H)-furanone–a new inhibitor of human synovial phospholipase A2 and platelet aggregation from fermentations of a Calyptella species (basidiomycetes).
Z Naturforsch-[C]. 1995 50(5-6):403-9.
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.