Assessing the Benefits of a “Hike in the Mountains” Using SPME

By: Loris Tonidandel, Ettore Sartori, Pietro Traldi, Reporter US Volume 26.1

Contributed Article

Loris Tonidandel1, Ettore Sartori2 and Pietro Traldi1

1.CNR-ISTM Corso Stati Uniti, 4 35100 Padova (Italy).
2. Parco Naturale Paneveggio Pale di San Martino, 38054 Tonadico (TN) Italy

Mountain hikers often claim to feel refreshed and renewed when climbing in mountains surrounded by coniferous trees. This may seem surprising since from 200 to 1500 meters the density of air decreases from 1.22 to 1.08 Kg/m3, which corresponds to a decrease of oxygen of about 12%. In principle this would make it more difficult to breathe, however some people feel that hiking in a mountain forest leads to easier and more beneficial respiration. This phenomenon is further supported by past approaches in the cure of pulmonary disease which recommended spending time in a mountain. This suggests the presence, in a forested mountain environment, of substances that aid in respiration.

In the researchers’ study, most of the attention was focused on the detection of terpenoids and other secondary metabolites released from plants, indicated as biologically active compounds. The project was based on the determination of a map related to the plant metabolites present in the atmosphere of the Paneveggio Natural Park in the Dolomite region (north-east region of Italy) in order to obtain an evaluation of the quality of the air present in the park (Figure 1).

Figure 1. Location of the Paneveggio Natural Park and Sampling Zones

The study was based on the sampling of biological volatile organic compounds (BVOCs) by portable SPME field samplers placed in different points of the park. Table 1 shows the atmospheric conditions and the predominant plants in the different sampling regions. An SPME fiber with a Carboxen™/Polydimethylsiloxane (75 μm) stationary phase was used to capture both non-polar and medium polarity volatile metabolites released from these plants (Figure 2). Considering the low concentration of BVOCs (at ppb level), fiber exposure was maintained for 5 hours. To prevent sample degradation and loss of the trapped compounds, each SPME fiber was stored at 0 °C and kept at the same temperature until sample analysis (about 24 hours later).

Table 1. Environmental Parameters of the Sampling Zones

Figure 2. An SPME Fiber with Carboxen/Polydimethylsiloxane (75 μm) Stationary Phase Captures Both Non-Polar and Medium Polarity Volatile Metabolites Released from Plants

Figure 3 shows a series of peaks due to the volatile terpenic species, while aldehydes and phenols are present in lower quantity. In zone 1, Norwegian Spruce (Picea Abies) prevails together with silver firs (Abies Alba) and beech trees (Fagus sylvatica). The results obtained are in good agreement with volatile metabolites typical of these kind of plants. Zone 2 has a larger distribution of broadleaved plants, which leads to slightly different results: some monoterpenic species (β-pinene and limonene) are present at lower concentrations while there is a clear increase of C12-C13 hydrocarbons. The results obtained in the five different zones are compared in Table 2.

Figure 3. A) Chromatogram of zone 1
B) Chromatogram of zone 4

Table 2. The Most Abundant VOCs Identified and Their Relative Abundances

The experimental data obtained allow us to make the following observations:

  1. Atmospheric sampling by SPME followed by GC-MS is highly effective for the qualitative determination of the BVOCs released from plants and present in a forest environment;
  2. The semi-qualitative approach adopted in these preliminary studies allows us to establish the relative concentration of different BVOCs for each zone.

The results summarized in Table 2 show that the BVOC content in air exhibits clear differences depending on altitude and surrounding vegetation.

From a therapeutic point of view, terpenoids represent an interesting class of the BVOCs, due to their antiinflammatory and anti-microbial activity for man and in general for animals. For more than a century, essential oils (e.g. trementine, pine extract) have been employed in the treatment of respiratory ailments. Trementine of larch, pine essences, trementine medicinal essences are the most common and described in the international pharmacopoeia. The therapeutic effect is mainly due to the most volatile constituents of oil and is related to their antioxidant activity. Considering that pulmonary and bronchial diseases and some skin infection are associated with the formation of the reactive oxygenated species (ROS), the antioxidant action of terpenes can reduce as well as prevent inflammation. Recent studies have demonstrated that terpenes, through their antioxidant activity, are also active in the prevention of arteriosclerosis, stroke and heart attack. They inhibit the low-density lipoprotein (LDL) oxidation, limiting the formation of products, which represent one of the causes of the above cited pathologies. These volatile constituents of essential oil are present, obviously in a forested mountain environment and the concentration in a forest can reach in excess of 10 ppb.

Through these considerations it is possible to recognize how healthy and therapeutic the atmosphere in the forest mainly covered of conifers as that of Paneveggio Natural Park is. It is to emphasise that the quality of the breathed in air is not only related to the absence of toxic pollutants in the atmosphere, but also to the presence of volatile plant metabolism products, which for their biological properties have a beneficial effect.

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