**1.5.1 Products of primary metabolism**

**Polysaccharides.** Polysaccharide molecules that form an integral part of the fungal cell wall also exhibit antimicrobial properties (Stamets, 2002). Polysaccharides are the most important components of fungal bioactive substances, proven to provide many medical and therapeutic possibilities (Fan et al., 2006) while their antibiotic effect is often specific to certain microorganisms (Stamets, 2002). Most of these compounds belong to glucans or heteroglycans (Fan et al., 2006). It is believed that the antibacterial and antifungal effects of β-glucan is based on the activation and strengthening of the immune response, and their use is recommended in combination with other antibiotics and immunostimulators in prevention and treatment of infectious diseases, especially immunocompromised individuals (Chen & Seviour, 2007).

**Proteins and polypeptides**. Proteins that act inhibitory on microorganisms are found frequently in organisms of plant and animal species, whereas their presence is rare in fungi (Wang & Ng, 2006). It is believed that these proteins are often positively charged, and that the mechanism of their action is realized by forming ion channels in cell membranes of microorganisms as well as by competitive binding to host cell polysaccharide receptors (Cowan, 1999). Proteins and peptides are isolated from macrofungi whose antimicrobial effect is limited to a small number of mostly phytopathogenic species (Table 1).

Antibacterial Agents from Lignicolous Macrofungi 369

**Dietary fibers**. High molecular weight substances that are excreted without digestion and absorption from the human body are called dietary fibers (Mizuno, 1999). Mushrooms contain these substances, which are composed of β-glucan, chitin and heteropolysaccharide (pectin substances, hemicellulose, polyuronidase, etc..) in the range of 10-50% in dry weight of the substance. Since they absorb harmful substances, hindering their intestinal absorption, dietary fibers are effective in preventing colon and rectal cancers (Mizuno, 1999). **Lectins**. Lectins (Latin legere = to take, to choose) are defined as carbohydrate-binding proteins of non-immune origin which agglutinate cells or precipitate polysaccharides or glycoconjugates (Kawagishi, 1995). Many species of plants, animals and microorganisms contain lectins, but the fungal lectin is still not explicitely defined. So far, several lectins were isolated from mushrooms of the genus Polyporales: *Grifola frondosa* (GFL), *Fomes fomentarius* (FFL), *Ganoderma lucidum* (GLLs). Some are isolated from the fruit bodies and some from the mushroom mycelium. GFL is cytotoxic to HeLa cells, and its activity is explained by binding of lectins to carbohydrate parts of the cell by preventing aggregation

Secondary metabolites produced by a large number of macrofungi have great therapeutic significance. These compounds occur as intermediate products of primary metabolism, but most of them are classified according to the five major metabolic sources (Table 2,3,4). The most productive pathways of synthesis of secondary metabolites are polyketide and

**Phenols** are one of the largest classes of secondary biomolecules, which are characterized by the presence of aromatic rings with hydroxyl group bonded directly to an aromatic hydrocarbon group. Although they are firstly identified in plants (Cowan, 1999), their presence was also observed in fungi (Barros et al., 2008, Mattila et al.*,* 2001, Karaman, 2002, Karaman et al., 2012a). In recent years, there was a causal relationship between the total content of these compounds with biological activities recorded in a large number of macrofungi (Barros et al., 2007), which include anti-inflammatory, antiallergic, anticancer, antihypertensive, antirheumatic and antibacterial activity. Antimicrobial properties of phenolics are explained by the presence of phenol hydroxyl groups, which number is in correlation with their toxicity toward microorganisms (Cowan, 1999). The possible mechanisms of their action include inhibition of extracellular microbial enzymes, deprivation of the substrates required for microbial growth or direct action on microbial metabolism through inhibition of oxidative phosphorylation, by sulfhydryl groups and

It has been shown that the antimicrobial effects of extracts of mushroom *Lactarius deliciosus, Sarcodon imbricatus* and *Tricholoma portentosum* directly correlated with total content of phenols and flavonoids in them (Barros et al., 2007). Extracts of all three fungi showed antibacterial effects on *Bacillus cereus* and antifungal to *Candida neoformans*, while the extract of mushrooms *Lactarius deliciosus* and efficiency demonstrated against *P. aeruginosa* and *Candida albicans*. High content of phenols has been recorded in lignicolous fungi *Meripilus giganteus, G. lucidum* and *Flammulina velutipes* in the form of coumarins and tannins, as well

mevalonate pathways (Zeidman et al.*,* 2005, from Giovaninni, 2006).

of cells (Wasser & Weis, 1999).

**1.5.2.1 Phenolic compounds** 

**1.5.2 Products of secondary metabolism** 

some non-specific interactions (Cowan, 1999).


Table 1. Polysaccharides, proteins and peptides from macrofungi with antimicrobial effect

antifungal: *Candida albicans*,

*S. aureus*. (Stamets, 2002)

antibacterial: *Mycobacterium tuberculosis*, *Listeria monocytogenes*, *S. aureus*, *M. luteus* i *B. cereus* (Stamets, 2002; Kitzberger et al., 2007; Chen & Seviour, 2007) antiviral: Herpes simplex-a type 1 (Stamets, 2002)

(Stamets, 2002; Kitzberger et al., 2007)

not yet investigated (*C. comatus* showing antibacterial activity) (Fan et al.*,* 2006).

*Mycosphaerella arachidicola* and *Physalospora* 

*oxysporum*, *Mycosphaerella arachidicola* and *Physalospora piricola*, as well as inhibitory effect on HIV-1 reverse transcriptase (Guo et

*Mycosphaerella arachidicola,* its N-terminal end shows certain similarity with antifungal protein liophyllin (Wang & Ng, 2004)

antibacterial effect against Gram + and Gram - bacteria: *B. mycoides, B. subtilis, E. coli, Klebisiella pneumoniae, Mycobacterium pheli, M. smegmatis, Photobacterium fischeri, P. aeruginosa , S. aureus* (Kavanagh et al.*,* 1950) antifungal effect: *Aspergillus niger*, *Gliomastix convoluta*, *Memnoinella echinata*, *Myrothecium verrucaria*, *Penicillium notatum*, *Phycomyces blackesleeanus*, *Stemphylium consortiale* and *Trichomonas mentagrophytes* (Ngai et al.*,*

not yet investigated, concerned as a reserve material (Fan et al., 2006)

*cinerea*, *Fusarium oxysporum* and *Physalospora piricola* (Wang & Ng, 2006)

antifungal effect : *Mycosphaerella arachidicola* and *Physalospora piricola*  (Takakura et al., 2001; Wang & Ng, 2006)

*piricola* (Chu *et* al., 2005)

*Ganoderma lucidum* antifungal to phytopathogens *Botrytis* 

*Pleurotus ostreatus* antifungal effect : *Fusarium oxysporum*,

*Tricholoma giganteum* antifungal activity against *Fusarium* 

al., 2005)

2005)

Table 1. Polysaccharides, proteins and peptides from macrofungi with antimicrobial effect

*Pleurotus eryngii* inhibition of *Fusarium oxysporum* and

**COMPOUNDS ORIGIN/SOURCE BIOLOGICAL ACTIVITY/REFERENCE** 

**SCHYZOPHYLLAN (SPG)** *Schyzophyllum commune* antifungal: *Candida albicans*, antibacterial:

**INTRACELLULAR POLYSACCHARIDES - containing 1,6-α-D-galactopyranosyl units, substituted on O-2 position with** α**-L-fucopyranosyl or 3-O-**α**-D-manopyranosyl-α-L-fucopyranosyl units.** Found

*Lentinus edodes* mycelial extract of *Lentinus edodes*

**KRESTIN (PSK),** proteoglycan *Trametes versicolor* antifungal effect: *C. albicans*

from the mycelium of *Coprinus comatus*

*pinicola*, *P. fomentarius* and *P. igniarius*

*Lyophyllum shimeiji* 

*Agrocybe dura*

*A. cylindracea* 

*Lepista nuda*

only in fungi and concerned as a type of reserve materials (Fan et al.*,* 2006)

**EXTRACELULAR POLYSACCHARIDES (noncellulose β-glucans)**

**GRIFOLAN (GRN)** *Grifola frondosa*

**FUCOGALACTAN** *G. applanatum* **MANOFUCOGALACTANES** *F. velutipes*, *Polyporus* 

**FUCOMANOGALACTANS** *Laetiporus sulphureus*

**LYOPHYLLIN** aqueous solution of

**FUCOGALACTAN CMP3** (hydrosoluble heteroglucan)

**GANODERMIN** 

**PLEUROSTRIN**  Peptide,

**TRICHOGIN**  peptide

**ERYNGIN** peptide,

**AGROCYBIN** peptide,

molecular weight ≈15 kDa

molecular weight of 7kDa

molecular weight of 10kDa

molecular weight of 9 kDa

protein,

**LENTINAN** 

**Dietary fibers**. High molecular weight substances that are excreted without digestion and absorption from the human body are called dietary fibers (Mizuno, 1999). Mushrooms contain these substances, which are composed of β-glucan, chitin and heteropolysaccharide (pectin substances, hemicellulose, polyuronidase, etc..) in the range of 10-50% in dry weight of the substance. Since they absorb harmful substances, hindering their intestinal absorption, dietary fibers are effective in preventing colon and rectal cancers (Mizuno, 1999).

**Lectins**. Lectins (Latin legere = to take, to choose) are defined as carbohydrate-binding proteins of non-immune origin which agglutinate cells or precipitate polysaccharides or glycoconjugates (Kawagishi, 1995). Many species of plants, animals and microorganisms contain lectins, but the fungal lectin is still not explicitely defined. So far, several lectins were isolated from mushrooms of the genus Polyporales: *Grifola frondosa* (GFL), *Fomes fomentarius* (FFL), *Ganoderma lucidum* (GLLs). Some are isolated from the fruit bodies and some from the mushroom mycelium. GFL is cytotoxic to HeLa cells, and its activity is explained by binding of lectins to carbohydrate parts of the cell by preventing aggregation of cells (Wasser & Weis, 1999).
