A comparative study on phytochemical screening, quantification of phenolic contents and antioxidant properties of different solvent extracts from various parts of Pistacia lentiscus L

2.1 Plant material

Pistacia lentiscus L. (leaves, twigs and fruits) were collected from two different regions of Morocco: Moulay Idriss Zerhoun (MIZ) Region: Fez-Meknes and Melloussa (MLS) Region: Tangier-Tetouan-AlHoceima, in October 2016. The Geographical coordinates of Moulay Idriss Zerhoun: N 33° 50′ 50,4636″; W 5° 19′ 0,3972″ and Melloussa N 35° 43′ 16,4676″; W 5° 39′ 30,9024″.

The fruits, twigs and leaves of P. lentiscus were air-dried for 15 days at room temperature and then was powdered separately and stored prior to further use.

2.2 Phytochemical screening of plant material

The phytochemical constituents of various parts (leaves, twigs and fruits) of P. lentiscus, were determined by different qualitative tests such as Alkaloid, Tannins, Anthraquinones, Flavonoids, Saponins, Sterols and Triterpenes, Oses and Holosides, Mucilages, Coumarins and Reducing Sugars. The tests were performed by the methods described below: (Diallo, 2005; Abdullahi et al., 2013; Joshi et al., 2013).

2.3 Extraction of crude extracts from different Pistacia lentiscus parts

The different extraction methods were followed to prepare crude extracts from leaves, twigs and fruits of Pistacia lentiscus L., from Melloussa and Moulay Idriss Zerhoun, by various solvents (hexane, ethyl acetate, methanol, ethanol and water).

2.4 Instrumentation

All spectrophotometric data were acquired using SHIMADZU UVmin-1240 UV-VIS spectrophotometer. Glass cuvettes (1 cm × 1 cm × 4.5 cm).

2.5 Determination of total phenolic content (TPC)

Total phenolic content in the Pistacia lentiscus extracts was determined to use the Folin-Ciocalteu method as described by Singleton et al. (1999). Briefly, 0.3 ml of the crude extract (1 mg/ml) was added to 1.5 ml Folin-Ciocalteu reagent (10/100). The mixing was incubated for six min and mixed with 1.2 ml of Na₂SO₄ (7.5%). The prepared samples were incubated in darkness for two hours, the absorbance made at 760 nm. Total phenolics were expressed as Gallic acid equivalents (GAE) in mg/g of crude extract. The data were presented on average ± SD for the triplicates. The content of the total phenolic was calculated using the linear equation from the calibration curve: $\text{A}=0\text{,}0099\text{X}+0\text{,}0289\text{;}{R}^2=0\text{,}999$ where A is the absorbance and X in mg/g (presented total phenolic content).

2.6 Antioxidant activities

2.7 Statistical analyses

All tests were conducted in triplicates and the data were presented on an average ± SD. The result was statistically analyzed using one-way ANOVA followed by Duncan's. Average values were considered statistically significant when P < 0.05. The correlation between the contents of total phenolic and antioxidant activities was determined as Pearson's correlation coefficient, the difference is considered statistically significant when P < 0.05.

3.1 Phytochemical screening

The phytochemical screening of various parts (leaves, twigs, and fruits) of Pistacia lentiscus L., showed the great presence of tannins, flavonoids, saponins, sterols, triterpenes, oses, holosides, reducing sugars and mucilages. While antraquinones free and anthraquinons combined were absent. Although, the alkaloids present in fruits and absent in the leaves and twigs (See Table 1).

3.2 Extraction yields of Pistacia lentiscus L

It is apparent through observing the extraction yields presented in Table 2, they differ significantly (p < 0.05) on the one hand, according to the plant parts, on the other hand, the solvent used. Methanol gives the best extraction yield an average of 37.344% on three samples (leaves, fruits, and twigs) of P. lentiscus from two regions, while hexane gave the lowest yield (15.177% on average). As for the plant parts usually, regardless of the extraction solvent, the extract fruits recorded the highest yields.

3.3 Total phenolic content (TPC)

The results of the TPC in all 30 studied extracts of various parts of Pistacia lentiscus L. by different solvents (Table 3) show a significant difference (p < 0.05) between the concentration of total phenolic. The great distinction between the plant parts appears due to the wealth of some and the poverty of others could be assigned to extraction solvents used, different environmental and climatic conditions (Özcan et al., 2009; Özcan, 2004; Couladis et al., 2003).

The results revealed that the Pistacia lentiscus leaves are very rich in phenolic compounds (varied from 345,95 ± 1,17 to 67,83 ± 0,36 mg of GAE/g of extract), followed by twigs (varied from 302,01 ± 1,12 to 48,71 ± 0,27 mg of GAE/g of extract) and the fruits (ranged between 192,68 ± 3,68 to 36,45 ± 0,45 mg of GAE/g of extract). The ethanol and water were great solvents than the others in extracting phenolic compounds from the extracts owing to their good solubilities and polarities, followed by methanol and the lower polarity solvents, particularly: ethyl acetate and hexane showed the lower capacity in extracting the phenolic compounds.

It can, therefore, be concluded that higher polar solvents were more effective at extracting phenolic compounds from all parts of the plant than less polar solvents (Galanakis et al., 2013).

There are several studies have confirmed that the Pistacia lentiscus L. plant is rich in phenolic compounds, this wealth increases as and when the polarity of extraction solvents used increases (Bampouli et al., 2014; Botsaris et al., 2015; Zitouni et al. 2016).

3.4 Antioxidant activities of the extracts of Pistacia lentiscus

3.5 Correlation

The dependency of antioxidant activity obtained through each assay, in relationship to the TPC, was also evaluated. The results show a very significant positive correlation in the cases of DPPH scavenging activity (R² = 0,8742) and TAC (R² = 0,968), in relationship to the content of phenols.

Although, there is a positive linear correlation among the antioxidant activities assessed by DPPH assay and TAC assay for R² = 0,839. The results indicated that the phenolic compounds in the different Pistacia lentiscus parts could be the main contributor to the antioxidant activities. This result was in similarity with many previous studies (Botsaris et al., 2015; Zitouni et al., 2016) Figs. 1 and 2.

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Fig. 1

Linear regression between TPC and the antioxidant activities by TAC assay and DPPH assay.

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Fig. 2

Linear regression between the antioxidant activities by TAC assay and DPPH assay.

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