Study of antioxidant activity of pine resin in Tunisia
The group of Tunisian pine represents a major forest capital around the Mediterranean. The resin of this plant was chosen on the basis of its use in local traditional medicine (Hatim et al., 2019). Therefore, the present investigation was focused on the study of the resin extraction process from different species of pine in order to get some supplementary data related to the composition and biological activity.
The exploitation of pine forests in Tunisia which covered up to 50% of the total forest area could contribute and generate additional income sources for forest populations. Until now, the resin extraction knowledge was very limited and outdated. In the present study, the assessment of the biological performance of the resin was the main objective in order to detect the antioxidant activity of three pine species in the Tunisian forest.
The antioxidant activity of the resin was tested in vitro by the DPPH test using increasing concentrations of the resin. The result was based essentially on the determination of the IC50 value. Therefore, we are focused on this part of this work on the detection of the different antioxidant pine resin activity between Aleppo pine, maritime pine, and stone pine. The most powerful free radical scavenger is recorded in the pine nut with the most important activity (IC50 = 15 ± 0.59mg / ml). The weakest free radical scavenger is recorded in Aleppo pine and presented the least activity (IC50 = 17 ± 0.11mg / ml).
The DPPH activity in the resin could be attributed to their high contents of phenolic compounds. However, the anti-radical activity depends on the chemical structure of phenolic compounds and on the availability of hydroxyl groups (OH) (Jayaprakasha et al., 2008).
Furthermore, the antioxidant activity is linked to the chemical composition of pine resins. It could be correlated with the majority or minority constituents or also with a synergy between them (Wang et al., 2008). The presence of α-pinene and limonene may explain the important antioxidant activity in pine nuts since they are considered to be major elements with a wide variety of biological activities (Wang et al., 2008).
Impacts and weaknesses
The DPPH test is usually used for the speed results since their used for the screening of molecules present in plant extracts (Fenglin et al., 2008). It should be noted that according to Prior and his collaborators (2005), there are factors to be observed when choosing the method to be used for the measurement of antioxidant activities because this activity is positively correlated with climatic conditions. Therefore, we don’t find yet the ideal method and season to measure the resin's antioxidant activity.
These results constitute a first step in the search for a biological active natural source substance. It would be necessary to improve this work by evaluating the antioxidant activity in vitro against other free radicals generated by enzymatic systems. The isolation and identification of phenolic compounds by more efficient methods (HPLC) and the use of other methods of evaluation of the antioxidant potential of the resin according to their principles will be interesting.