Biological activity of glycopolymers from Basidiomycetes mushrooms

This article gives an overview of the literature data on the biological activity of glycopolymers separated from cultural liquid, fruit body and mycelia of Basidiomycetes mushroom. The structure and properties of mushrooms polysaccharides were considered as well as the dependence of their biological activity on the physical and chemical properties. A possibility of using the preparations based on the mushrooms polysaccharides for plant protection as well as for therapy and prophylactics of human and animal diseases was discussed.

In tro duc tion.Higher Basidiomycetes mush rooms have been used in folk med i cine all over the world.They are es pe cially pop u lar in ori en tal folk med i cine.In the early hours of Yuan Dy nasty in China (1280-1368) peo ple al ready knew the heal ing prop erties of mush rooms, which were con sid ered to be im portant treat ing means, and the im ages of their fruit bod ies are found in lit er a ture, mas ter pieces, in the form of deco ra tions, etc. Cu ra tive fea tures of Basidiomy cetes mush rooms are also men tioned in an cient lit er a ture of Eu rope and North Amer ica, where they are called ar tistic wood knots [1].How ever, in ves ti ga tion on phar maco log i cal and med i cal fea tures of Basiodiomycetes has started only re cently [2].The re search ers have proven that Basiodiomycetes mush rooms are an end less source of sub stances with cu ra tive fea tures re lated to nu merous dis eases [3].In re cent years this in for ma tion has trig gered in ter est in search ing for bi o log i cally ac tive com po nents of Basidiomycetes mush rooms and their study, as well as cre ation of food ad di tives and med i cal prep a ra tions on the ba sis of fruit bod ies and the products of mush room me tab o lism.In China 270 mushroom spe cies with pos si ble med i cal ap pli ca tion are reg is tered and more than 100 of them are used in tra ditional med i cine [4].The anal y sis of lit er a ture data ev idences to the fact that to day most re searches are conducted with Basidiomycetes mush rooms of Auricularia, Flamulina, Ganoderma, Grifola, Hericium, Lentinus (Lentinula), Pleurotus, Trametes, Coprinus, Laetiporus, Panus, Shizophyllum and Tremella genera.
Sub stances, ex tracted from mush rooms and their cul tural liq uids, were used as the ba sis of prep a ra tions, widely used as adaptogens and immunogens [5].It was also re vealed that mush rooms are ca pa ble of reg u lat ing (sta bi liz ing) the im mune sys tem, sup port ing ho meo stasis, treat ing and pre vent ing tu mours and car diac diseases, sta bi liz ing cho les terol level in blood, pre vent ing thrombi for ma tion, and reg u lat ing blood pres sure [6].While study ing the chem i cal na ture of func tion ally active com po nents, ob tained from fruit bod ies of Basidiomycetes, the au thors of [7] dis cov ered that these sub stances con tain poly sac cha rides.In the fur ther work they iso lated the fol low ing prep a ra tions: krestin -from my ce lium of Trametes versicolor, lentinanfrom fruit bod ies of Lentinus edodes, and schizophyllan -from me tab o lism prod ucts of Schizophyllum com mune.Be sides, ac tive pro tein compo nents were iso lated from fruit bod ies and mycelia of mush rooms -poricyn from Poria corticola and mucopro teins (calvacyn) from Calvacia gi gan tean [6,8].
Bi o log i cally ac tive car bo hy drate-con tain ing polymers are dif fer ent for dif fer ent mush rooms spe cies.The strains of the same Basidiomycetes spe cies produce [the] com bi na tions with dif fer ent struc tural and func tional fea tures.For in stance, proteoglycan krestin, iso lated from SM-101 strain of T. versicolor in Ja pan, and the one from CoV-1 strain of the same spe cies in China, have dif fer ent pro tein mol e cules, bound to polysaccharide [8].
The aim of the cur rent work is to an a lyze the lit er ature data, re lated to the struc tural and func tional va riety of car bo hy drate-con tain ing biopolymers (glycans, glycoproteins, proteoglycans), pro duced by Basidiomycetes.
The chemical structure and biological activity of glycans of Basidiomycetes mushrooms.As for chemical structure the polysaccharides of mushrooms are mainly presented by glycans with different types of glicosidic linkage.Basically glucose has b-(1®3) or b-(1®4) links or sequences of b-(1®3)-, (1®4)-links with b-(1®6)-link in the main chain.There are true heteroglycans as well as glycoproteins, containing carbohydrate and protein components.The side chains of heteropolysaccharides are usually linked to the main chain via (1®6)-linkage [9].
It was re vealed that antitumour ac tiv ity is mostly inher ent in b-D-glucans -lin ear poly mers, mono mers of which are glu cose or other D-monosaccharides.The glycans were clas si fied de pend ing on the type of main structural unit of the poly mer.For in stance, the struc tural units of ga lac tans, fucans, xylans, and mannans are galactose, fucose, xylose, and mannose, re spec tively [9,10].
Bi o log i cally ac tive b-D-glucan has three-di mensional, dexiotropic spa tial struc ture.Poly sac cha rides with sim i lar antitumour and immunostimulating features, iso lated from fruit bod ies or mycelia of mushrooms, may dif fer in struc ture, chem i cal com po si tion, and phys i cal pa ram e ters [11].Their ac tiv ity may depend on the size, form, and de gree of mol e cule branching, wa ter sol u bil ity, etc. Biopolymers pos sess antitumour fea tures if their mol e cules are linked with b-(1®3) links in the main chain, and with b-(1®6)-links in the side chains.b-glycans with prevail ing (1®6)-links in the main chain are char ac ter ized by a lower ac tiv ity.How ever, it should be men tioned that high mo lec u lar mass glycans are more ac tive than glycans with low mo lec u lar mass [12,13].Be sides, higher antitumour ac tiv ity is in her ent to poly sac charides, iso lated from fruit bod ies of mush rooms, rather than to those from mycelia.It may also de pend on the com po si tion of nutrient medium and cultivation conditions of the latter.
Antitumour fea tures were re vealed for the compounds with some what dif fer ent struc ture, in par tic ular, for het ero-b-glucans, b-glycoproteins, a-mano-b-glucans, a-glycoproteins, and protein complexes with heteroglucans [14].
The pres ence of a ter tiary struc ture in [a] three-chain mol e cule of mush room b-(1®3)-glycans is a nec es sary con di tion for immunomodulating and other bi o log i cal and phar ma co log i cal fea tures of macromolecules, for in stance, for the im pact on ni trogen-acid syn the sis of macrophages and ac ti va tion of G-fac tor.For ex am ple, when macromolecules of lentinan are denaturated to the pri mary struc ture us ing dimethyl sulfoxide, urine, or NaOH, its immunostimulating fea tures are lost, and its antitumour prop er ties de creased in ac cor dance to the de na tur ation de gree [15].It tes ti fies to the fact that immunomodulating ac tiv ity de pends on the pres ence of a ter tiary struc ture and hy dro philic groups on the mol e cule sur face rather than on the order of monosaccharides in the carbohydrate chain.
The chem i cal struc ture of poly sac cha rides, iso lated from fruit bod ies and mycelia of L. edodes (lentinan) [16] and S. com mune (schizophyllan), was mainly inves ti gated.The qual i ta tive anal y sis of poly sac cha rides shows that they con tain glu cose, galactose, and mannose, and the glycans, glu cose of which is linked via (1®3)-or (1®4)-glycosidic link age, are char ac teris tics of their struc tures.For in stance, lentinan of 950-1050 kDa, is pre sented by b-1, 3-D-glycan with branch ing struc ture.Af ter ev ery five glu cose res i dues in C 6 po si tion, two glucopiranose res i dues, linked via b-1, 6-glucoside bond, de vi ate from the main chain, [16].Some side chains are pre sented by sin gle glu cose res i dues in C 6 po si tion [18].
The re sults, prov ing cor re la tion be tween antitumour ac tiv ity and con fig u ra tion of three-chain struc ture of glycans, were also ob tained for schizophyllan.The polysaccharide stud ied were in the range of 5•10 3 • -1.3•10 5 Da.The in ves ti ga tion on their abil ity to in hibit de vel op ment of Sar coma 180 in mice re vealed that high antitumour ac tiv ity is in her ent to the sam ples with mo lec u lar mass 9•10 4 Da.The prep a rations with mo lec u lar mass lower 10 4 Da in hibit tu mour de vel op ment less ef fec tively or do not in hibit it at all.The in ves ti ga tion of schizophyllan con for ma tion in wa ter so lu tion showed that the mol e cules with mo lec ular mass over 9•10 4 Da are pre sented by a dexiotropic tri ple he lix while the mol e cules with lower mo lec u lar mass have a con for ma tion of a tri ple he lix with some sin gle chains ob served among them.Mo lec u lar mass of tri ple chains is 5•10 3 Da, which proves the de pend ence of the ability to inhibit tumours on the size of a triple helix molecule [17].
How ever, the in duc tion of syn the sis of g-in ter feron and col ony-stim u lat ing fac tor does not de pend on the mol e cule struc ture and is spe cific for a-con fig u ra tion of the mol e cules.It deopends on the pres ence of a-(1®3)-glycosidic bond in car bo hy drate chain rather than on the mol e cule ter tiary struc ture.Con trary to b-(1®3)-glycans, ther a peu tic fea tures of which are revealed in the range of 500-2000 kDa, no de pend ence on the mo lec u lar mass was ob served for a-(1®3)-glu-curonoxylomannane, iso lated from jelly mush rooms [19].Acid glucuronoxylomannane, ob tained from fruit bod ies of Tremella fuciformis, has three-di men sional struc ture of the main chain as a left-hand spi ral [20].For in stance, Gao et alt.re vealed that all the frac tions with mo lec u lar mass from 1 to 53 kDa, ex tracted via acid hy dro ly sis from fruit bod ies of T. fuciformis, induce the syn the sis of interleukin-6 (IL-6) sim i larly to non-hydrolized frac tions [21].Cul tural liq uid of T. mesenterica was used to ob tain the polysaccharide, the main chain of which is glycosided by xylose and glucoronic acid and pre sented via a-(1®3)-linked D-manose [22].
Mush room poly sac cha rides are com posed of both homopolysaccharides, mainly ex tracted in wa ter, and heteropolysaccharides, con tain ing xylose, mannose, galactose, and uronic ac ids.They are iso lated from water so lu tion us ing salt pre cip i ta tion and leach ing [23].
Be sides antitumour and immunostimulating ac tivity, in her ent to some types of glycans, there are polysac cha rides with a wide spec trum of other bi o log i cal fea tures.Inonotus ge nus, I.obliquus in par tic u lar, is a well-known pro ducer of sub stances with var i ous cu rative fea tures.Bi o log i cally ac tive glycoproteins, isolated from fruit bod ies, sclerotium and my ce lium of I. obliquus, were used as a ba sis for de vel op ment of Bifungin prep a ra tion, for both treat ment and health improvement in general [24,25].
An other spe cies of this ge nus, I. le vis, pro duces a con sid er able amount of exopolysaccharides with dif ferent phar ma co log i cal fea tures [25].The anal y sis of monosaccharide com po si tion of poly sac cha rides, obtained from the cul tural liq uid, showed that they con tain fucose, xylose, galactose, mannose, glu cose, and methyl galactose.An ion-ex change chro ma tog ra phy dem onstrated that the ex tract con tains two poly sac cha ridesgalactan and mannane.The mo lec u lar mass of galactan is about 5 kDa, and mannane -over 15 kDa, re spectively.In a main part of the mol e cule, galactan is a lin ear chain of (1®6)-linked b-galactopiranose res i dues of galactose, ir reg u larly meth yl ated in the third po si tion of the ox y gen atom.Ac cord ing to the chem i cal struc ture, mannane is an b-(1®6)-linked mannopiranose in the main chain and an b-(1®2)-mannopiranose -in the side chains.Nei ther pro teins nor lipids were re vealed in the polysaccharide [26].
Wa ter ex trac tion al lowed ob tain ing polysaccharide prep a ra tion KS-2 from my ce lium of L. edodes.Accord ing to its chem i cal na ture this prep a ra tion is an b-glycoprotein, con tain ing such amino ac ids as serine, threonine, alanine, and proline.Aque ous ex tracts from my ce lium and cul tural liq uid con tain poly sac cha rides with glu cose, galactose, xylose, arabinose, mannose, and fruc tose.The prep a ra tions, ob tained from my celium, are also com posed of de riv a tives of nu cleic ac ids, vitamins of group B, and ergosterol [27].
Glycoprotein K (PSK), con tain ing 62% of polysaccharide and 38% of pro tein, was ex tracted from T. (Coriolus) versicolor [19,28].Polysaccharide PSK is pre sented by b-(1-3), (1-4)-glycan, side chains of which are linked to the main one via b-(1-3)-link.The polysaccharide part is com posed of glu cose and an in sig nif i cant amount of galactose, mannose, xylose, and fucose.The pro tein part of the mol e cule is rich in asparagine and glutamic amino ac ids, valine, and leucin.Polysaccharide and pro tein parts are con nected via O-glycosidic link age be tween the serine or threonine res i dues of the pro tein and OH-groups of car bo hy drates, and via N-glucosidic link age -be tween asparagine acid and OH-groups of glu cose.The mo lec u lar mass of polysaccharide is 94-100 kDa.The prep a ra tion has con sid er able bi o log i cal value as an in hib i tor of some human tumours [13,27,28].
Besides PSK (krestin), glycoprotein PSP was also obtained from T. versicolor (first obtained from COU-1 strain).A chemical structure of PSP differs from that of PSK.A qualitative analysis revealed that it contained arabinose and ramnose along with fucose.The polysaccharide chain is presented by b-glycan, in which glucose molecules are linked via (1-4)-, (1-3)-, and (1-2)-glycoside linkage.Its molecular mass is about 100 kDa [27].
It means that func tion ally ac tive glycopolymers, pro duced by Basidiomycetes, mainly be long to glycans of dif fer ent struc ture and glycoproteins.They have sim i lar im pact on hu man or gan ism and its de fen sive sys tems.The pri mary struc ture of glycans is un like to be the most de ci sive fac tor of their bi o log i cal ac tiv ity; more im por tant is a for ma tion of higher conformational struc tures, which de ter mine bi o log i cal features of the glycopolymers.
The data on biological activity of products, obtained from Basidiomycetes mushrooms, are summarized in Table.
Types of biological activity of glycans.Antitumour activity of glycans.Antitumour activity of Basidiomycetes mushrooms was first demonstrated by the authors of [25], who tested extracts from fruit bodies of Boletus edulis and other Homobasidiomycetes species while treating mice with Sarcoma 180 [29].In 1958 calvacin was extracted from fruit bodies of C. gigantean, widely used in folk medicine.This preparation was tested as an antitumour medicine in laboratory conditions using different models.In the culture of HeLa cells it demonstrated an inhibiting activity against many types of experimental tumours: Sarcoma 180, breast adenocarcinoma 755, leukemia L-1210 [27].More than 7000 cultures were checked in the study of extracts from Basidiomycetes mushrooms, which allowed obtaining preparations active against Ehrlich carcinoma, Sarcoma 180, breast cancer, and leukemia [3,5,11].
Therefore, the investigation of higher mushrooms as antitumour means allowed revealing antitumour activity of about 650 Basidiomycetes species , in particular, Auriculariales, Tremellales, and Polyporales orders, Gasteromycetideae and Agaricomycetideae genera, etc.
Clinical research proved the most active tumour inhibitors to be lentinan, extracted from L. edodes, D-fractions from Grifola frondosa, schizophyllan (SPG) from S. commune, krestin and glycoprotein PSP from T. versicolor.Lentinan, schizophyllan and PSK are currently used in Japan as official preparations in tumour treatment.Their chemical structure is b-D-glucans (b-D-glycoproteins).
Mushroom-produced polysaccharides do not destroy tumour cells directly.Their antitumour effect is determined by activation of the host's immune system.The mentioned substances do not hurt an organism, rather they help it adapt to the changes in environment and stresses, by supporting its main systems, in particular, nervous, hormonal and immune ones [27].
Mechanism of antitumour and immunomodulating action.
Antitumour activity of mushroom polysaccharides is based on activation of the thymus-depending mechanism of immune response.It is proven by the inhibition of anticarcinogenic action of lentinan and other polysaccharides in the presence of inhibitors of macrophages.Therefore, after specific recognition of tumor cells, the polysaccharides directly influence the predecessors of T-cells and the intensity of cytokine synthesis by macrophages.Mushroom Biological activity of products of Basidiomycetes mushrooms metabolism glycans are also known as stimulators of synthesis of natural killers, E-cells, B-cells, and immune-dependent macrophages.
For in stance, in an or gan ism with tu mour, lentinan is ca pa ble of re stor ing the ac tiv ity of T-cells to the normal state, which re sults in com plete ac ti va tion of humoral im mu nity [30].This polysaccharide is revealed to in duce the high-rate trans port of neu tro phils, eosinophils, and granu lo cytes to the tar get, and to inten sify the se cre tory fea tures of ac tive ox y gen and the cytokines pro duc tion by macrophages.Be sides, lentinan in creases the macrophages cytotoxicity to metastases, stim u lates nor mal and al ter na tive ways of the com ple ment sys tem, and pro motes split ting of C3 to C3a and C3b, thus im prov ing the func tion al ity of macrophages [30].The im pact of lentinan on the ac tivity of macrophages re sults in the in crease of the amount of such sub stances as a fac tor of acute-phase pro teins in duc tion, a fac tor of interleukin 1 and IL-3 in duc tion, and a col ony-stim u lat ing fac tor in blood Lentinan induces the ac tiv ity of var i ous types of antitumour effector cells, in par tic u lar, T-kill ers, nat u ral kill ers, cytotoxic macrophages, which may have an im pact on tar get cells.Lentinan was shown to in crease the sen sitiv ity of thymocytes to IL-2 and susceptibility of normal killers to activation factor and IL-2 [18].
The ability of receptor of complement type 3 three (CR3, also known as Mac-1, CD11b/CD18 or as a M b 2 -integrin) to recognize â-glucans allowed the authors of [31] to suppose that it is the main b-glucan receptor on leucocytes which conditions all immunomodulating effects of these carbohydrates.When phagocytes CR3 are linked to iC3b on the membrane of bacteria or yeasts, it triggers the launch of phagocytosis or cytotoxic degranulation, as there is simultaneous recognition of iC3b via the site of binding I-domain of CD11b, and specific microbe polysaccharides -via the lectin site, located at COOH-end of I-domain.However, when phagocytes or natural killers (NK) CR3 are linked to iC3b on erythrocytes or tumour cells, decreasing the number of CR3-sites for polysaccharides binding to the membrane, neither lysis of cells nor cytotoxic effects are observed.
Cytotoxicity of neutrophils, macrophages and CR3 receptors of NK cells for tumour tissue is achieved through a primary contact of lymphocytes with b-glucans which inhibits natural resistance of tumour cells [31].The activation of cytotoxicity of natural killers of CR3 under the impact of b-glucan in the organism with iC3b-opsonised tumours is accompanied by secretion of the factor of a tumour necrosis (TNF-a), interferon a (IFN-a), IFN-g and IL-6 [31].Besides, it was revealed that binding of the ligand, located on the surface of tumour cells, to b-glucan receptor stimulates the activation of a nucleus factor êB (NF-êB) in myelogenous cells of human leukemia U-937 [31].
Many mushroom and yeast glycans are capable of stimulating the system of mononuclear phagocytosis (macrophages, monocytes) and some lymphocytes (NK) for the production of interferons and interleukins, i.e. the system, which belongs to the first level of cell protection.Detection of infected or transformed cells provides complete humoral and cell immune response.For instance, treatment of mononuclear cells of peripheral blood with aqueous extract of fruit bodies of L. edodes results in higher level of TNF-a, IL-1b, IL-10 and IL-12 [30].
b-(1-3)-D-glucan, extracted from G. frondosa, increases the production of IL-1, IL-6, and TNF-a in the culture of cells of marcophages RAW 264.7.D-fraction of b-glucan brings up significant increase in the expression of TNF-a by normal killers, IL-12 -by macrophages, g-IFN -by T-cells, g-IFN, IL-12g70 and IL-18 -by cells of pancreas and lymph nodes [32].
Schizophyllan, isolated from the cultural liquid of S. commune, stimulates the production of g-IFN and IL-8 in the culture of PBMC cells.When modified to one-chain conformation, schizophyllan induces the formation of TNF-a and IL-8 in the culture of cells of human monocytes U-937 and TNF-a -in PBMC [17].
An aqueous extract of PSP has significant impact on the increase in the production of IL-1 and IL-6 and decrease in the synthesis of IL-8 in the culture of human promyelocytes HL-60.For instance, the introduction of this preparation in mice triples T-lymphocytes concentration.PSP also induces the IFN synthesis with remarkably higher intensity for a-IFN than g-IFN.PSK stimulates the formation of IL-1 in PBMC culture much more efficiently than that of TNF [31].A higher amount of IL-1 is accumulated in cells rather than in the nutrient medium, while IL-1 is located in both cultural liquid and cells.In the organism with a tumour, lentinan is capable of restoring the activity of T-cells to the normal level, which results in complete activation of the humoral immunity [30].PSK is notable for a similar effect [19].Immunomodulating activity of these polysaccharides may be related to their impact on the hormonal factors which participate in tumour development, and this activity is considerably inhibited with the introduction of thyroxin or hydrocortisone.
Polysaccharides are capable of restoring tumour-specific antigen-dependent hypersensitivity of the organism [33].PSP introduction in mice with Sarcoma 180 results in significant improvement of the general state.It was revealed that this preparation prevents thymus atrophy and increases the amount of hemolysin, IgG and C3 complement.
Extract of G. lucidum mycelium, injected into mice with T-lymphoma, considerably inhibits tumour growth and prolongs life of the infected animals [34].The investigation on purified polysaccharides, obtained from mycelium and fruit bodies of this mushroom, revealed that their activity is conditioned by the ability to inhibit tumour growth in mice: Ca755 tumour -by 88%, Sarcoma 180 -by 71%, T-lymphoma -by 79% [35].The experiments on rats demonstrated that the preparations, obtained from fruit bodies and mycelia of G.fondosa [36] and T. versicolor [8], also have inhibiting impact on various types of tumours.A considerable antitumour effect is inherent in the polysaccharide, isolated from fruit bodies, mycelia, and cultural liquid of mushrooms of Tremella genus [37].The mechanism of antitumour activity is conditioned by the stimulation of immune system.
It was re vealed that the prep a ra tion in creases phagocytosis of intraperitoneal macrophages of mice re lated to red blood cells of chick ens.Be sides, the polysaccharide stim u lates the ac tiv ity of red bone marrow, nor mal izes the level of lym pho cytes pro lif er a tion, and pro motes pro duc tion of IL-2 in age ing mice to that of young ones.It means that poly sac cha rides of mushrooms of Tremella ge nus have immunomodulating and immunorestoring fea tures.It is rather im por tant since sim i lar prep a ra tions are ca pa ble of re stor ing the functions of im mune sys tem un der var i ous kinds of stress and im mu no de fi ciency, in par tic u lar, in case of acquired immunodeficiency syndrome (AIDS).
Hypolipidemic activity.An ability to decrease the cholesterol level in blood was found for many mushrooms.It was determined that adding a dry powder of fruit bodies of P. ostreatus mushroom to the food of rats decreased cholesterol in their blood serum and liver [38].While investigating the mechanism of action of this preparation, the inhibition of cholesterol synthesis (including that increased due to the activity of lovastatin -an inhibitor of mevalonic acid synthesis) was revealed as well as the capability of this preparation to adsorb cholesterol molecules and to activate lecithin-cholesterol-acytil-transferase, which accelerates further cholesterol transformation.
On the contrary, the extract from L. edodes decreases the concentration of free cholesterol in blood plasma because of acceleration of cholesterol accumulation in liver and its removal from blood circulation [39].This effect is related to eritadenine, obtained from fruit bodies of the mushroom: it activates the cholesterol break-up and its removal from blood.Eritadenine is known to decrease the level of cholesterol and lipids in the blood of animals.The addition of eritadenine to the food of animals during 7 days results in the decrease in the level of cholesterol by 25% which is more efficient than a diet.Fruit bodies of Aspergillus tereus were used to isolate mevinolin, an inhibitor of the enzyme, participating in early stages of cholesterol synthesis [37,40].
Similar results were obtained with a dry powder from fruit bodies of G. lucidum, added to food for animals.A lipo-cholesteric effect was demonstrated, i.e. a decrease in the level of cholesterol in atherogenic lipoproteids [34,41].A hypocholesteric effect of G. lucidum was revealed in vitro, ex vivo and on animal models of hamsters and pigs.Its activity is related to the lanosterol derivative, capable of decreasing the synthesis of cholesterol; in particular, it can inhibit the transformation of 24, 25-dehydrolanosterol into cholesterol and indirectly inhibit the activity of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase [41].This effect of mushrooms allows us to assume a potential of products of mushroom metabolism in prophylactics of atherosclerosis and decreasing of the risk of cardiac diseases.
Impact on blood pressure.It was observed that besides hypocholesteric effect, the mushrooms metabolites can regulate blood pressure.at both hypertony and hypotony.It is an inherent characteristic of mushrooms of Pleurotus genus, as well as of G. frondosa, L. edodes, Polyporus confluens, and G. lucidum [2,3,36].There are different mechanisms of action of different preparations, isolated from mushrooms.In particular, the extracts from L. edodes inhibit agglutination of thrombocytes, and therefore, have antithrombotic activity.Polysaccharides, isolated from T. fuciforms, decrease [size of thrombi and blood viscosity, inhibit adhesion of thrombocytes, and influence positively coagulation characteristics of animals blood [42].Glycoprotein, obtained from mycelium in the course of deep cultivation of Trametes sp., demonstrated a similar action in experiments in vitro and on animal model [37].Preparations of Armillriella mellea are able to decrease the heart rate, peripheral and cardiac resistance of vessels [43].
Antibacterial activity.The compounds, obtained from cultural liquid, mycelia, and fruit bodies of mushrooms, are characterized by antiviral, antibacterial, and antifungal activity.Taking into account modern state of chemotherapy, especially the occurrence of pathogen strains, resistant to preparations, this type of activity of mushroom metabolites is of considerable interest for researchers.
Mycelium of Ganoderma preifferi was used to obtain ganomycin, which inhibits the development of methicillin-resistant Staphylococcus aureus and several other microorganisms [44].The fruit bodies of L. edodes were used to obtain cortinelin, which demonstrated antibiotic activity against Candida albicans, S. aureus, and Bacillus subtilis [45].In vitro experiments showed that the extracts of mycelium of this mushroom inhibit the growth of phytopathogenic bacteria (P.syringae pv.glycinea, P. syringae pv.tabaci, X. campestris pv.glycines, Erwinia amylovora, Ralstoma solanacearum, Cflaccumfaciens pv.flaccumfaciens) and causative agents, affecting foodstuffs and humans (B.cereus, Escherichia coli, Listeria monocytogenes, Sa monella typhimurium, S. aureus) [8,46].While adding the extract of this mushroom mycelium to the medium with sprouts of tomatoes and haricot, it was demonstrated that contrary to control plants the experimental ones had no symptoms of bacterial rot [46], caused by R. solanacearum or Curtobacterium flaccumfaciens pv.Flaccumfaciens.No signs of the disease were observed during 40 days.These results indicate a possible presence of antibiotic substances in mushroom mycelium.
The investigation on antibacterial and antifungal features of extracts of mycelium and filtrates of the cultural liquid of different strains of L. edodes proves their capability of inhibiting growth of gram-positive and gram-negative bacteria, yeasts, and filamentous mushrooms.
[The] Mushroom activity is strain-specific.
The elaborated preparations had inhibiting impact on B. subtilis, B. cereus subsp.mycoides, C. albicans, and A. niger, and the addition of ethanolic extracts to the nutrient medium with grown bacteria and mushrooms resulted in inhibition of T. harzianum development.The active components of the mentioned preparations were lentinamycin and eritadenine, the former having higher antibiotic activity [47].
The substances, extracted from fruit bodies of L. edodes, had antibacterial features regarding C. albicans.Their addition to the nutrient medium for cultivation of microorganisms resulted in significant decrease of the number of colony-forming units of E. coli O-114, S. aureus, and St. faecalis [34].Lentinan also inhibits the development of Mycobacterium tuberculosis and Listeria monocytogenes [30].
The products, obtained from the mycelium of P. ostreatus (Jacq.:Fr)Kumm, decreased the growth of A. niger and mold [48].
Polysaccharide PSK from T. versicolor inhibited the growth of C. albicans, and in the in vivo experiments krestin increased considerably the resistance of mice to such microorganisms as Pseudomonas aeruginosa, S. aureus, C. albicans, Klebsiella pneumoniae, M. leprae, L. monocytogenes, Serratia marcescens, St. pneumoniae, Bacteroides fragilis, Cryptococcus neoformans, and Aspergillus fumigatus [8].The mechanism of antimicrobial action is based on the activation of bactericidal features of polymorphonuclears as well as on the induction of antimicrobial cytokines (necrosis factor of tumours and IL-1).A similar effect was revealed for aqueous extracts from fruit bodies of G. frondosa and Lepista nuda.It was observed that the symptoms of chronic yeast infection of women were significantly milder after everyday use of the preparations [49].
Antiviral activity.Polysaccharides, produced by Basidiomycetes mushrooms, are capable of inhibiting the development of viral infections.This type of activity was observed for many mushrooms species.The mechanism of antiviral effect may consist in hindering the adsorption of a viral part on the cell, in blocking viral enzymes and synthesis of nucleic acids of viruses, as well as in improving organism immunity.As of today the main investigations have been conducted on the model of viruses, known as causative agents of opportunistic infections in patients with AIDS and pathogens, widely spread among both humans and animals.
For instance, the aqueous extract of A. blazei inhibits the development of the human herpes simplex virus, type 1 (HSV-1) and ovine herpes virus.This preparation in concentrations of 50 and 100 µg/ml inhibits pathogen development in the cell by 78%.Inhibition was higher if the virus was pretreated with the preparation prior to before infecting cells, i.e. the substance had higher viricidal activity, which evidences to its impact on surface proteins of the virus and to adsorption of the latter on the cell.Besides, this preparation also demonstrated therapeutic activity, which testifies to its participation in inhibition of virus replication at later stages [50].
The aqueous and ethanolic extracts of A. blazei inhibit cytopathic action of the Western equine encephalitis virus (WEEV) and HSV in the culture of Vero cells, the ethanolic extract having higher activity [51].The mentioned polysaccharide preparations inhibit the development of [the] poliovirus, type 1, in the culture of Hep-2 cells.The investigated substances were found to be active while treating the cells after their infecting with the virus, but they had no virucidal effect, i.e. they inhibited early stages of virus replication rather than influenced virus adsorption [52].
An antiherpetic activity was revealed for the protein, isolated from fruit bodies of G. frondosa.This preparation inhibited virus replication in vitro and significantly decreased the pathogen production when used locally [53].The products, obtained from the mycelium of G. lucidum, inhibit the development of HSV in the cell culture.The mechanism of their action consists in hindering virus adsorption on the cell due to blocking both cell and viral receptors [54].Treatment of patients with chicken pox, using the aqueous extract from fruit bodies of G. lucidum, moderated the clinical course and shortened the disease duration [55].
Water soluble compounds, obtained from the mycelium of L. edodes (jLs and jLs-18 strains), demonstrated antiviral and immunomodulating properties.The antiviral effect is based on inhibition of virions maturing in cells, which was revealed on the HSV model [27] both in vitro and in vivo.Besides, lentinan demonstrates antiviral activity against vesicular stomatitis virus, encephalitis, Abelson virus, adenovirus, type 12, stimulates resistance of mice to respiratory infection and influenza virus, type A [27].This preparation also inhibits the development of the human immunodeficiency virus.The chemotherapy of human T-lymphocytes culture with azidotymidine either alone or in combination with lentinan, showed that the combined prepation reduced the percentage of infected T-cells more effectively than azidotymidine alone.The mechanism of action of lentinan and its sulphated derivatives, which also showed antiviral activity, consists in inhibition of HIV replication and prevention of virion adsorption on cells [56].
The ethanolic extracts of I. hispidus fruit bodies, hispolon and hispidin, demonstrated antiviral activity regarding influenza types A and B in the culture of chicken embryos [57].The aqueous extract of Russula paludosa in the concentration of 1 mg/ml inhibited the activity of HIV-1 by 97.6% [58].The preparations, obtained from the cultural liquid of L. edodes by either sedimentation with ethanol or extraction inhibit HIV development in the culture of MT-4 cells, the first procedure providing lower activity.It was demonstrated that these preparations block the primary stage of virus reproduction [56].D-fraction, obtained from G. fondosa, decreased the reproduction of hepatitis B virus.Its usage in combination with interferon results in considerably higher activity of both substances, i.e.D-fraction has synergic effect regarding IFN activity, which makes the complex preparation promising in treatment of chronic hepatitis B [59].
Therefore, numerous investigations proved that polysaccharides and glycoproteins of Basidiomycetes mushrooms are capable of inhibiting the activity of viruses of humans and animals.It has been demonstrated only recently that these preparations may inhibit viruses of plants [60].For instance, lectin, isolated from fruit bodies of Agrocybe aegerita by water extraction, delays the development of TMV-infection in plants of Nicotiana glutinosa.Lectin in the concentrations of 50 µg/ml and 200 µg/ml provided 62.5% and 84.3% inhibition of necrosis, respectively.The mechanism of antiviral action consists in prevention of infecting plant cells due to lectin attachment]to their viral parts.
The investigation on antiphytoviral features of polysaccharide of glucuronoxylomannane (GXM), isolated from the cultural liquid of T. mesenterica, demonstrated that this glycan inhibited TMV-infection of tobacco and datura plants [61].The polysaccharide added to virus suspension had lower activity than that introduced into the intercellular space of a leaf.
The results presented testify to the fact that GXM influences the virus prior to its infection as well as the processes in a cell.In particular, the polysaccharide may inhibit the virus reproduction and induce the resistance of plants de novo, which is proven by sensitivity of this activity to the inhibitor of RNA transcription on DNA matrix of actinomycin D [62].
Antiallergenic activity.There are some mushroom extracts inhibiting the activity of immune system, which may be used in allergy treatment.An introduction of dry ethanolic extracts of fruit bodies of Hypsizygus marmoreus, Flammulina velutipes, Philiota nameko, and P. eryngii into the food for mice resulted in disappearance of allergy symptoms [63].The antiallergenic activity was also revealed for several components of G. lucidum.For instance, ganoderic acid C and D slow down the histamine discharge by mast cells of rats.T. populinum mushrooms, used as a food additive, causes the regression of allergic reaction in patients with nettle rash [2].
Conclusions.The analysis of literature data demonstrates that the structural components and extra-cellular products of Basidiomycetes mushrooms metabolism, in particular, carbohydrate biopolymers, are currently under active investigation.As their curative features have long been known, this stage consists in scientific justification of this activity and study on the influence spectrum of glycans.In particular, numerous works are dedicated to the study on immunomodulating and antitumour properties.
It was revealed that the level and type of polysaccharides activity depend on the producer and the macromolecule structure.For instance, antitumour features are inherent in b-D-glucans with prevailing b-(1®3)-links, while the induction of [IFN] synthesis is attributed to a-molecules.Besides, the glucans activity is determined by the degree of molecule branching, tertiary structure, water solubility, molecule charge, etc.
The polysaccharides, produced by Basidiomycetes mushrooms, are characterized by antibiotic features and the ability to inhibit the development of viral infections.The mechanisms of glycans action on bacteria and viruses differ; they may consist either in the stimulation of immune response of the organism or in direct action on the pathogen.Glycans block the adsorption processes of pathogens, inhibit their reproduction in the cell and activate natural mechanisms of cell protection.The study on antiviral and antibacterial features of polysaccharides is of great importance due to the appearance of new strains of microorganisms, resistant to modern preparations.
Up to date, a significant number of preparations have been developed mainly as food additives and are widely used to improve the general health.Besides, there are current clinical investigations of the preparations based on mushroom polysaccharides, which are elaborated as additional means in the therapy of oncological diseases, HIV-infection, hepatitis B and C viruses, herpes viruses, etc.The patients, who took the mentioned substances along with chemotherapy, had better general condition and life quality compared to those who did not take mushroom polysaccharides.In Japan these preparations are used as official medicine for general health improvement, prophylactics of malignant tumours, therapy of oncological diseases, and prevention of metastases.
Therefore, Basidiomycetes mushrooms are a source of substances with various medical and biological features.The preparations on their basis are non-toxic and increases considerably the degree of patients' survival.Further investigations on these substances open new perspectives in the search for medical means to treat currently incurable diseases and to improve the organism functioning.