Mushrooms are medicinal foods used extensively in traditional medicine for combating diet-related diseases, treating chronic diseases, delay ageing and increase life expectancy (Khatun et al., 2012). Mushrooms’ medicinal properties are owing to the possession of wide range of secondary metabolites that are of high therapeutic values. Some of these medicinal properties are antibacterial, antifungal, antiviral, anticancer, anti-inflam-matory and antioxidants (Wasser, 2002; Ameri et al., 2011; Keles et al., 2011). Moreover, the combination of vitamins, essential mineral salts, protein, polysaccharides, fibres and low lipid content in mushrooms are dietary supplements to strengthen the immune system (Wani et al., 2010). Species of Termitomyces, Ganoderma, Pleurotus, Cordyceps sinensis, Inonotus obliquus, Polyporus umbellatus, Shizophyllum commune and others are medicinal macrofungi with nutraceutical properties (Barros et al., 2008; Jiang and Sliva, 2010; and Hesham et al., 2013).

The nutraceutical activities of medicinal macrofungi had been traced to the presence of phytochemicals. The biological and metabolic diversity of mushrooms are due to their ability to utilize several substrates; decomposing dead organic matters and thus explore different habitat for colonization (Thatoi and Singdevsachan, 2014). This bioconversion of organic waste materials has not only brought about biodegradation but plays a major role in nutrient cycles that are of great benefits to man and nature. Coriolopsis polyzona is a white rot fungus commonly found on decaying woods and known to mineralize lignin and phenolic compounds by their multienzyme systems (Alaoui et al., 2008). The bio-assimilation of higher molecular compounds by macrofungi has led to the secretion of biological active compounds that are of great medicinal importance. However, the continuous searching for novel bioactive compounds in medicinal mushrooms will yield greater success in pharmaceuticals and food science. This will definitely provide perpetual solution to the significant increase in antibiotics resistance by pathogenic organisms and continuous failure witnessed in some chemotherapy agents.

Restaurants in Akure metropolis dispose their wastewater and remnant foods to the environment without treatment. These wastes are laden with pathogenic organisms that are resistant to antibiotics (Ogidi and Oyetayo, 2013). The indiscriminate dumping of refuse containing pathogenic organisms into the environment had contributed to the transfer of resistance genes in the ecosystem, contamination of watercourses and causes of eutrophication (Akpor and Muchie, 2011).

Fungi spores are widely dispersed into air and these spores are known to contribute to allergic diseases (Hageskal et al., 2009). Brakhage et al. (2010) reported that fungi produce volatile organic compounds that contribute to ill health. Therefore the emerging and transfer of resistance genes by pathogenic fungi containing spores in food chain cannot be overemphasized. This situation has contributed to the ineffectiveness of antibiotics. The search for effective antifungal agents had increased recently. Attention had been turned to mushrooms because they are known to contain bioactive compounds that are effective against microbial entities (Lindequist et al., 2005). The present study is therefore aimed at assessing the antifungal property of extracts of Coriolopsis polyzona, a wild macrofungus, against fungi isolated from wastewater and remnant foods.

Collection of macrofungus

Samples of macrofungus were collected from farmland and nearby forest at the Federal University of Technology Akure, Nigeria (Lat 07° 14^IN Long 05° 11^IE). Sample of fruiting body was morpholo-gically identified and confirmed by molecular methods.

Preparation of extracts from C. polyzona

Collected samples of C. polyzona were dried and ground to powder using mill machine (Retsch GmbH 5657 HAAN). The fine powder of C. polyzona, 100 g each, was soaked in acetone and methanol for 48 h. The filtrates obtained were dried using rotary evaporator (RE-52A, UNION Laboratories, England) and labelled as ACE and MCE for acetone extract and methanol extract respectively.

Isolation and Identification of fungi

Samples of wastewater and remnant foods were examined microbiologically using standard methods. The microscopic identification was done according to Chander (2002) and Barnett et al. (1983). The identified fungi were maintained on Potato dextrose agar (PDA Lab M) slants at 4°Cin refrigerator for subsequent used.

Quantitative determination of phytochemical contents in extracts of C. polyzona

The flavonoid content was determined by aluminum chloride colorimetric method described by Singleton et al. (1999). The methods described by Harborne (1998) were adopted to quantify alkaloid content of the extracts while tannins, saponins, tepernoids and steroid amount was quantified using the method described by AOAC (2003).

Antifungal Activities of the crude extracts and purified fractions

The antifungal activities of extracts were determined by Poison food technique (Parajuli et al., 2005). Volume of 1.0 ml each concentration (50, 100 150 mg/ml) of acetone extract (ACE) and methanol extract (MCE) were aseptically poured into Petri dish followed by the addition of equal amount of PDA. The Petri dish was agitated while adding PDA so as to get even mixture of the contents. PDA plates with dimethyl sulfoxide (DMSO) serves as control. Seven days old culture of the test fungi were used to prepare inoculums discs (6mm diameter) using cork borer. Fungal inoculum was aseptically placed upside down in the centre of each plate containing MCE and ACE. The experiment was performed in three replicates. The average diameter of fungal colonies was measured on the 7th day after inoculation and percentage of mycelia growth inhibition was calculated. The Percentage growth inhibitions in different concentrations were calculated as:

Percentage growth inhibition=

Where, g_c = Growth of mycelia colony after incubation period in control set subtracting the diameter of inoculums disc; g_t = Growth of mycelia colony after incubation period in treatment set subtracting the diameter of inoculums disc.

The antifungal effect of partially purified fractions was also carried out according to the method above.

Partial purification of extracts

The separation of extracts was done according to the method of Owolabi  and  Olarinoye  (2008).  The column chromatography was filled with petroleum ether (500ml), 60 grams of silica gel (60-120mesh) was tamped into column chromatography. The sample of extracts was mixed with silica gel and ground together to homogenize. This was transferred with spatula into the packed column chromatography.The column was opened and eluants were collected in 100ml aliquot portion. The polarity of mobile phase was varied by introducing chloroform and methanol. Thin layer chromatography (TLC) plate was saturated in chromatographic tank containing chloroform: methanol (10: 5) solvent systems.

Infra-red spectroscopic analysis

The presence of functional groups in Coriolopsis polyzona extracts was assessed using FT Infra-Red spectrophotometer (Spectrum BX).The FT IR wave number (cm^-1) obtained was interpreted according to Willams (1982).

Statistical analysis

The experiment was carried out in triplicates. Data obtained were analyzed using one way analysis of variance and means were compared by Duncan’s Multiple Range Test using (SPSS 17.0 version). 

Species of fungi isolated from remnant foods and wastewater collected from restaurants are shown in Table 1. The fungi isolated are Aspergillus fumigatus, Aspergillus niger, Mucor mucedo, Penicillium chrysogenum, Apsergillus flavus, Fusarium oxysporum, and Penicillium italicium. Figure 1 shows the percentage yield of methanol and acetone extracts. Acetone has the highest percentage yield (6.5%) than methanol (4.7%). Table 2 shows the phytochemical contents of C. polyzona extracts. Acetone extract (ACE) had alkaloid content of 14.20 mg/g while methanol extract (MCE) had 11.6 mg/g. Flavonoids content of the extracts ranged from 4.55 to 6.80 mg/g and tannins is 5.2 and 7.7mg/g for ACE and MCE respectively.

The mycelia inhibition of C. polyzona extracts ranged from 4.7 to 37.7% against isolated fungi from remnant foods and 2.7 to 37.3% against isolated fungi from wastewater samples at different concentration of 50, 100 and 150 mg/ml (Tables 3 and 4). Acetone and methanol extracts of C. polyzona exhibited highest mycelia inhibition against Penicillium chrysogenum and A. niger than mycelia inhibition caused by fluconazole (Table 3). Acetone extract shows mycelia inhibition of 37.7% against P. chrysogenum that was found to show resistance against Ketoconazole (Table 4). Plate 1a shows the mycelia inhibition of C. polyzona against isolated fungi while Plate 1b containing DMSO (control) shows no mycelia inhibition against tested fungi. The percentage of mycelia inhibition observed in purified extracts is closely related to the commercial antibiotics used as positive control (Tables 3, 4 and 5). The purified fractions of C. polyzona also exhibited more potent mycelia inhibition against P. chrysogenum, A. fumigatus, F. oxysporum and A. niger as shown in Table 5. Table 6 shows the functional groups of bioactive compounds in C. polyzona extracts. The results of FTIR analysis revealed the presence of the following functional groups; hydroxyl (OH), alkyl (C-H), carbonyl (C=O) and aromatic ring (C=C).

The practice of disposing wastes from restaurants without treatment had been in existence without check in most communities in Nigeria. This has led to build up of chemical and biological pollutants in the environment. The accumulation of biological pollutants such as microorganisms in the environment beyond self-purification will be a threat to public health (Akpor and Muchie, 2011). Build-up of microorganisms in the environment has also contributed to the problem of resistance of microorganisms to commercial antibiotics as a result of exchange of resistant genes (Frost et al., 2005). This research work therefore assessed the antifungal effect of extracts obtained from a wild macrofungus, C. polyzona, against fungi isolated from restaurant wastes.

The genera of fungi isolated from remnant foods and wastewater from restaurants in Akure metropolis includes Aspergillus, Peniculliumand Fusarium. The occurrence of different species of fungicould be due to the exposure time of food during processing and after processing to airborne fungi, the microbiological quality of water used for food preparation, sanitary quality of the equipment and health status of employees. The importance of these fungi to endanger human health had been highlighted (Warris et al., 2001). Hedayati et al. (2011) had earlier isolated these groups of fungi from hospital drinking water in Iran. The findings of Oranusi et al. (2011) revealed that some of these fungi are of public health importance. Makun et al. (2009) also reported that many of these fungi species produce toxic metabolites in Nigerian staples and ascribed the mycotoxins to species of Aspergillus, Penicillium, Fusarium and Mucor.

The phytochemical contents in extracts of C. polyzona are flavonoids, alkaloids, tannins, saponins and steroids. These phytochemicals had been reported to possess antifungal effects (De Silva et al., 2013). Therefore, the inhibitory potentials of extracts obtained from C. polyzona were well pronounced against isolated fungi from waste-water and remnant foods (Tables 2, 3 and 4). Coriolopsis species had earlier been reported to possess antimicrobial properties (Oyetayo et al., 2010). Gbolagade et al. (2007) had also earlier reported the antifungal properties of some Nigerian higher fungi on species of pathogenic fungi.

The percentage inhibition of mycelial growth by extracts of C. polyzona was similar to the antifungal activities of some wild macrofungi reported by Imtiaj and Lee (2007).The mycelia inhibition (2.7 to 37.3%) caused by extracts of C. polyzona on the isolated fungi conformed to results obtained by Ayodele and Idoko (2011) who reported mycelia inhibition of 13.82 to 32.10% against A. niger and Penicillium notatum by culture filtrate of Lentinus squarrosulus, Psathyrella atroumbonata, Volvorella volvacea and Coprinellus micaceus.

The mycelia inhibition of these isolated fungi by C. polyzona extracts could be attributed to the presence of secondary metabolites, which comprises of different functional groups such as ketones, hydroxyl, methyl, carboxylic acid and aromatic ring. Compounds possessing these functional groups are known to be potentially useful phytochemicals that can exhibit antimicrobial activities (Cowan, 1999). Barros et al. (2008) and Rai et al. (2005) had associated the medicinal values of macrofungi to diversities of secondary metabolites that contained different functional groups of biologically active compounds.

The possession of antifungal properties by extracts of C. polyzona show that it contains bioactive compounds that could be extracted and explored as new drugs against the continuous failure of chemotherapies and prevalent resistance of microorganisms to commonly used antibiotics.

The authors did not declare any conflict of interest.