LEM which is an aqueous extract of a mycelial culture of Lentinus Edodes and has a sugar composition composed of arabinose, xylose, glucose, mannose, galasctose, fucose and rhamnose, as well as a fraction of LEM which corresponds to molecular weights of 10,000 to 1,000,000 daltons and has a sugar composition composed of arabinose, xylose, glucose, mannose and galactose are provided as agents for inhibiting the adsorption of herpesviruses such as herpes simplex to the cells.

A protocol using natural extracts which permit amelioration of malignancies in humans is disclosed. The protocol mandatorily includes an extract of Lentinus edodes and mung beans, and optionally further includes the combined extract of Hedyotis diffusa and Scutellaria barbata.

It is an object of the present invention to provide immunopotentiators and immunotherapeutic formulations available at low cost and having a benign side effect profile. According to the present invention, an LAK activity enhancer containing an extract of Lentinus edodes mycelium and an LAK activity-enhancing formulation containing said enhancer are provided.

The inhibitor of Hepatitis B virus and HIV activity according to the present invention comprises a Lentinus edodes mycelium extract obtained by the steps of inoculating Lentinus edodes fungus in a solid culture medium comprising bagasse, then disentangling the solid culture medium containing the proliferated mycelium, adding water and at least one enzyme selected from a group consisting of cellulase, protease and glucosidase to the disentangled solid culture medium with keeping the solid culture medium at 30 to 50.degree. C., grinding and milling the solid culture medium in the presence of the enzyme to obtain a Lentinus edodes mycelium extract, and then heating the extract to a temperature of not higher than 95.degree. C. to inactivate the enzyme and sterilize the extract.

EEM-S obtained by extracting with hot water or a lower alcohol at least one mushroom selected from among Lentinus edodes, Flammulina velutipes, Hypsizygus marmoreus, Pleurotus ostreatus, Pholiota nameko, Grifola fondosa, Volvariella speciosa ver. speciosa, Lyophllum decastes, blanc du pays, Tricholoma matsutake, Ganoderma lucidum and Phellinus yucatensis, treating the obtained extract by the molecular sieve method and thus eliminating low-molecular-weight and high-molecular-weight fractions: and preparations thereof. This EEM-S exerts physiological effects such as anticancer, immunopotentiating, antioxidative, hypotensive and hypoglycemic effects.