The plant raw materials that were the subject of this study are:

­ Mushrooms of the genus Termitomycse sp. (Figure 1(a)) from the locality of Brazzaville in southwestern Congo;

­ Mushrooms of the genus Pleurotus sp. (Figure 1(b)). These fungi were collected at the foot of trees in the southwest of Brazzaville Congo.

The drying equipment consisted essentially of solar dryer of boat type (Figure 2(a)) and the Memmrt brand oven (Figure 2(b))

1) Preparation of extracts

The different extracts made for the determination of total polyphenols and flavonoids were obtained by mixing 30 g of the plant material in 2 × 500 mL of a 50% hydroethanol solution in the same proportions 50% (v/v). The mixture was then macerated under stirring for 72 h and filtered with filter paper. The filtrate obtained was concentrated to dryness at 50˚C under reduced pressure using a rotary evaporator model N-1 (Eyela, Tokyo Rikakikal Co., Ltd., Japan) and stored in an oven at 25˚C and kept in a cool place (+4˚C) waiting for analysis (Figure 2).

2) Determination of total polyphenols

The determination of the concentration of total phenols in the different samples was performed by the Folin Ciocalteu technique described by [18]. The Folin Ciocalteu reagent is reduced by the phenyl-copper complex which gives a blue coloration with maximum absorbance at 760 nm.

0.1 mL of the hydroethanol extract of mushrooms of concentration 2 mg/mL is introduced into a 2 mL Eppendorff tube. Subsequently 0.9 mL of distilled water and 0.9 mL of Folin-Ciocalteu reagent (1 N) are added and immediately afterwards 0.2 mL of Na₂CO₃ solution (20%) is added. The resulting mixture is incubated at room temperature for about 40 minutes in the dark. The absorbance is then measured with a spectrophotometer at 725 nm against a methanol solution used as blank. Note that a calibration line is previously performed before the analysis with gallic acid under the same conditions as the samples to be analyzed. The results obtained are expressed in mg gallic acid equivalent per gram of dry matter (EAG/gMs).

3) Determination of total flavonoids

The total flavonoid content of the extract of mushroom types was obtained by using aluminum trichloride (AlCl₃) [23]. In a 100 mL flask, 250 μL of the hydroethanol extract was successively introduced.

1 mL of distilled water, 7.5 μL of NaNO₂ (5%). The mixture was allowed to stand for 5 minutes. Then 75 μL of AlCl₃ (10%), was added before letting it stand again for 6 min. Then 500 μL of NaOH (1 N) and 2.5 mL of distilled water were added successively to the mixture. The analyses were performed at 25˚C.

The following reagents: NaOH, NaNO₂, Na₂CO₃, ethyl acetate, and formic acid were all from Merck.

Absorbance was measured by UV-Visible spectrophotometer, model Gd-752n at 510 nm and results were expressed as mg catechin equivalent per gram of dry matter (mgECa/gMs).

The antioxidant activity of the extract was measured using DPPH radical.

The evaluation of free radical activity was performed using 5 mL of 1.1- diphenyl-2-picrylhydrazyl (DPPH at 10 mg in 250 mL ethanol) solution and 100 µL of each extract diluted to concentrations ranging from 10 to 0.312 mg/mL, mixed in EDTA glass tubes. The DPPH radical is dissolved in 0.004% methanol solution stored at room temperature protected from light before use.

After 30 minutes of incubation in the dark, the free radical scavenging activity was measured by spectrophotometer at 517 nm in the dark [24]. The percentage of inhibition was calculated by the following relationship:

I % = ( A517 of the white − A517 of the sample ) A517 of the white × 100

With A517: Absorbance at 517 nm.

The reaction of the reduction of DPPH with phenolic compounds is shown in Figure 3 below.

Figure 4 shows the results of polyphenols and flavonoids of the studied mushrooms.

This figure reveals the interesting contents of total polyphenols and flavonoids of the studied samples. The results revealed that the samples studied are mainly composed of total polyphenols. The concentrations of polyphenols, for Termitomyces sp. vary from 11.18 mgEAG/gMs (fresh), from 15.20 mgEAG/gMs (microwave drying at 280 W), from 13.61 mgEAG/gMs (oven drying at 60˚C), and from 9.81 mgEAG/gMs (solar dryer at 40˚C); while for Pleurotus sp., the

concentrations varied from 8.7 mgEAG/gMs (fresh), 13.79 mgEAG/gMs (microwave drying at 280 W), 8.36 mgEAG/gMs (oven drying at 60˚C), and 8.98 mgEAG/gMs (solar dryer at 40˚C).

Flavonoid contents for Termitomyces sp. ranged from 0.4964 mgECa/gMs (fresh), 0.5797 mgECa/gMs (microwave drying at 280 W), 0.729 mgECa/gMs (oven drying at 60˚C) and 0.5671 mgECa/gMs (solar dryer at 40˚C); while for Pleurotus sp., the concentrations vary from 0.4114 mgECa/gMs (fresh), 0.842 mgECa/gMs (microwave oven at drying at 280 W), 1.06 mgECa/gMs (oven drying at 60˚C), 0.425 mgECa/gMs (solar dryer at 40˚C).

The studied mushrooms are a good source of flavonoids.

Similar results were found by Muanda, N. F. [23] on several plants and showed that the extracts of D. Oliveri are quantitatively richer in phenolic compounds (polyphenols, flavonoids) with contents of 22 to 70 mgEAG/gMs of PPT and 96.73 to 120.8 mgECa/gMs of FVT.

The results on the extracts of D. Adscendens leaves gave 11.15 mgEAG/gMs of PPT and 12.94 mgEAG/gMs of FVT.

The results on the extracts of F. capensis gave 21.33 mgEAG/gMs of PPT and 115.2 mgEAG/gMs of FVT.

The results from the root barks of S. Longependuculata are richer in polyphonic compounds with values of 9.86 mg EGa/gMs of PPT and 5.85 mgECa/gMs of FVT. The work reported by Sompila, A. W. G. T., et al., [25] revealed that the fronds of P. aquilinum are rich in polyphenols and flavonoids; similarly, the work of Nguie, R., et al. [26] revealed that the aquatic plant L. schlechteri was also rich in hydro-ethanol extracts.

Figure 5 presents the results of the anti-free radical activity of the studied fungi.

Figure 5 reveals interesting antioxidant properties of the studied samples. For Termitomyces sp., the concentrations vary from 21.25 mg/mL (fresh), 13.02 mg/mL (microwave drying), 25.08 mg/mL (oven drying), and 22.25 mg/mL (solar dryer); while for Pleurotus sp., they vary from 26.11 mg/mL (fresh), 15.96 mg/mL (microwave oven drying), 39.90 mg/mL (oven drying), 31.60 mg/mL (solar dryer). The studied mushrooms have interesting antioxidant properties. These results corroborate with those found by [19] on the same plants which show that the antioxidant capacity of the extracts analyzed is relatively important. This is the case for the extracts of D. oliveri “Et (2.9 µg/mL), Er (2.8 µg/mL), F (2.7 µg/mL)”; V. doniana “Et (2.9 µg/mL), Er (2.9 µg/mL), F (2.9 µg/mL)”; D. adscendens “F (4 µg/mL)”; F. capensis “Et (2.9 µg/mL)” and S. rebaudiana “Er (2.9 µg/mL)”.

Barks of the roots of S. longependuculata “Er (5.5 µg/mL)” and extracts of F. capensis “Er (8.8 µg/mL)”. Extracts of leaves of F. capensis (10.2 µg/mL), essential oils S. rebaudiana IC (23.3 µg/mL) and F. capensis (19.3 µg/mL).