**3.** *S. nigra* **mono and sesquiterpenic metabolites composition**

Terpenic compounds form a large and structurally diverse family of secondary metabolites derived from C5 isoprene units, with over 35,000 known structures [35]. The volatile and semivolatile ones, that is, mono and sesquiterpenic compounds, result from two main biosynthetic routes, starting from the mevalonate and the methylerythritol phosphate pathways (**Figure 1**). These are produced through the activity of a large family of enzymes, the mono and sesquiterpene synthases and cyclases, but others are formed through transformation of the initial

**Metabolites Elderflowers<sup>a</sup> Elderberriesa References**

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d-Limoneneb ✓ 2.24–9.92 [31, 32, 37, 38, 41–43]

Myrcene ✓ ✓ [31, 37, 38, 42] Ocimeneb ✓ 1.55–9.32 [31, 32, 34, 41] *α*-Phellandrene ✓ ✓ [32, 34, 37, 41] *α*-Pinene ✓ ✓ [31, 37] *β*-Pinene ✓ ✓ [31, 37, 38] *α*-Terpinene ✓ ✓ [32, 34, 41] *γ*-Terpinene ✓ ✓ [31, 32, 34, 41] Terpinolene ✓ ✓ [31, 32, 37, 38]

Camphene — ✓ [37] 3-Carene ✓ ✓ [31, 38, 39] Cosmene ✓ — [31, 40] *o-*Cymene — ✓ [41] *p*-Cymene ✓ — [31, 32, 37] 2,6-Dimethyl-2,6-octadiene ✓ — [31]

1,3,8-p-Menthatriene — ✓ [37]

Verbenene — ✓ [37]

Artemisia alcohol — ✓ [37] Borneol — ✓ [37, 41] Camphor ✓ ✓ [37, 41, 42] 3-Caren-2-ol — ✓ [37] Carvacrol ✓ — [42] Carvone ✓ ✓ [37, 42] 1,8-Cineole ✓ ✓ [31, 34, 41, 42] Citral ✓ ✓ [31, 37, 41] Citronellal ✓ — [31, 37] Citronellol ✓ ✓ [34, 37, 42, 44]

Citronellyl formate ✓ — [31] p-Cymen-8-ol — ✓ [37] Dehydroxylinalool oxide ✓ [31] Dihydromyrcenol — ✓ [37]

**Monoterpenic compounds**

*Hydrocarbon type*

*Oxygen-containing type*

**Figure 1.** Simplified mono and sesquiterpenic compounds biosynthetic pathways, illustrated with the routes for linalool, caryophyllene and humulene found in *S. nigra*. MS, monoterpene synthases; SS, sesquiterpene synthases; PP, pyrophosphate.

products by acylation, dehydrogenation, oxidation, and other reaction types, such as acetylation [35, 36]. For instance, in **Figure 1**, illustrates the biosynthesis of linalool, caryophyllene, and humulene, three compounds present in *S. nigra* plant. The biosynthesis occurs from their respective linear precursors, geranyl pyrophosphate and farnesyl pyrophosphate, originating. Both linear and cyclic structures [35].

Information about mono and sesquiterpenic compounds from elderflowers and elderberries is still scarce and disperse. Thus, to systematize this data, the information related with ripe berries and fresh flowers and minimally processed products, such as infusions, syrups, and juices, is presented in **Table 1**. The reported studies are mainly focused on analytes' identification rather than on their quantification, however, when available, quantitative data is also provided.

So far, 89 mono and sesquiterpenic compounds are reported in elderflowers (64) and elderberries (61). Recent studies using an advanced gas chromatographic methodology (comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry detection—GC × GC-ToFMS) have contributed to substantially increase the knowledge about *S. nigra* berries and flowers volatile terpenic profile by reporting dozens


products by acylation, dehydrogenation, oxidation, and other reaction types, such as acetylation [35, 36]. For instance, in **Figure 1**, illustrates the biosynthesis of linalool, caryophyllene, and humulene, three compounds present in *S. nigra* plant. The biosynthesis occurs from their respective linear precursors, geranyl pyrophosphate and farnesyl pyrophosphate, originat-

**Figure 1.** Simplified mono and sesquiterpenic compounds biosynthetic pathways, illustrated with the routes for linalool, caryophyllene and humulene found in *S. nigra*. MS, monoterpene synthases; SS, sesquiterpene synthases; PP,

Information about mono and sesquiterpenic compounds from elderflowers and elderberries is still scarce and disperse. Thus, to systematize this data, the information related with ripe berries and fresh flowers and minimally processed products, such as infusions, syrups, and juices, is presented in **Table 1**. The reported studies are mainly focused on analytes' identification rather than on their quantification, however, when available, quantitative data is also provided.

So far, 89 mono and sesquiterpenic compounds are reported in elderflowers (64) and elderberries (61). Recent studies using an advanced gas chromatographic methodology (comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry detection—GC × GC-ToFMS) have contributed to substantially increase the knowledge about *S. nigra* berries and flowers volatile terpenic profile by reporting dozens

ing. Both linear and cyclic structures [35].

62 Secondary Metabolites - Sources and Applications

pyrophosphate.


of monoterpenic and sesquiterpenic compounds for the first time in these matrices [31, 37]. Representative total ion GC × GC chromatogram contour plots from fresh elderflowers and ripe elderberries are illustrated in **Figure 2**, highlighting the complexity of the natural

μg/kg of fresh berries; Marks "✓" correspond to nonquantified compounds or quantified but not expressed as berry or

**Table 1.** Mono and sesquiterpenic compounds reported in *S. nigra* L. berries and flowers and related products, such as

**Metabolites Elderflowers<sup>a</sup> Elderberriesa References** Verbenone ✓ — [31]

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Aromadendrene ✓ ✓ [31, 37] *α*-Bergamotene ✓ — [31] *β*-Bourbonene ✓ ✓ [31, 37] Cadinene ✓ ✓ [31, 37] *α*-Calacorene — ✓ [37] Calamenene ✓ ✓ [31, 37] Calarene — ✓ [43]

*β*-Caryophyllene ✓ ✓ [31, 32, 34, 37] *α*-Copaene ✓ ✓ [31, 37, 42] Cubebene ✓ ✓ [31, 37] *β*-Elemene ✓ ✓ [31, 37] *α*-Farnesene ✓ — [31] D-Germacrene ✓ — [31] *α*-Humulene — ✓ [31, 38] Longifolene — ✓ [37] *α*-Muurolene — ✓ [37]

*β*-Bourbonen-13-ol — ✓ [37] t-Cadinol — ✓ [37] Caryophyllene oxide — ✓ [37] Cubenol — ✓ [37] Globulol — ✓ [37] Epiglobulol — ✓ [37]

When available, quantitative information was reported;

**Sesquiterpenic compounds**

*Hydrocarbon type*

matrices.

a

b

*Oxygen-containing type*

flower weight basis.

infusions, syrups, or juices.


a When available, quantitative information was reported;

**Metabolites Elderflowers<sup>a</sup> Elderberriesa References** Fenchol — ✓ [37] Fenchone ✓ — [31] Geranial ✓ ✓ [31, 41] Geraniolb ✓ 1.05–7.21 [31, 32, 37, 41]

64 Secondary Metabolites - Sources and Applications

Geranyl acetate — ✓ [37] Hydroxylinalool ✓ — [32, 34]

Hydroxycitronellol — ✓ [41] Lilac aldehyde ✓ — [31] Lilac alcohol ✓ — [31] Limonene oxide ✓ — [31]

Linalool methyl ether ✓ — [31] Menthol ✓ ✓ [37, 41, 42] Methyl citronellate ✓ — [31] Methyl geranate ✓ — [31] Myrcenol ✓ — [31] Myternol ✓ — [31]

Nerol ✓ ✓ [31, 32, 37, 41]

Nerol oxide<sup>b</sup> ✓ 1.02–7.80 [31, 34, 41, 42, 45]

*E*-Rose oxide ✓ ✓ [31, 34, 37, 40–42, 45] *Z*-Rose oxideb ✓ 1.68–8.34 [31, 34, 37, 40–42, 45]

*α*-Terpineolb ✓ 70.85–2699.56 [31, 37, 41, 42, 45] Terpinen-4-ol ✓ ✓ [31, 32, 37, 41]

Nerolidol ✓ — [42]

Pinocarvone — ✓ [37]

Tagetone ✓ — [31]

*β*-Terpinyl acetate — ✓ [37] *α*-Thujone ✓ — [31, 42] *β*-Thujone ✓ — [31, 42] Thymol ✓ — [42]

Hotrienol<sup>b</sup> ✓ 2.56–8.08 [31, 34, 37, 40–44]

Linaloolb ✓ 1.18–128.89 [31, 37, 40–43, 45] *E*-Linalool oxide (furanic form) ✓ ✓ [31, 37, 40, 42, 44] *Z*-Linalool oxide (furanic form) ✓ ✓ [31, 37, 40, 42, 44] *E*-Linalool oxide (pyranic form) ✓ — [31, 32, 34, 40, 42, 44] *Z*-Linalool oxide (pyranic form) ✓ — [31, 32, 34, 40, 42, 44]

> b μg/kg of fresh berries; Marks "✓" correspond to nonquantified compounds or quantified but not expressed as berry or flower weight basis.

> **Table 1.** Mono and sesquiterpenic compounds reported in *S. nigra* L. berries and flowers and related products, such as infusions, syrups, or juices.

> of monoterpenic and sesquiterpenic compounds for the first time in these matrices [31, 37]. Representative total ion GC × GC chromatogram contour plots from fresh elderflowers and ripe elderberries are illustrated in **Figure 2**, highlighting the complexity of the natural matrices.

linalool (1.2–128.9 μg/kg of fresh berries) and *α*-terpineol (70.8–2699.5 μg/kg of fresh berries) (**Figure 3**) [41]. Monoterpenic compounds also prevailed in its juice, ranging from 8.9 to 77.2 ng/mL, limonene and linalool being the main monoterpenic components (**Figure 3**) [38]. Sesquiterpenic compounds are present in lower amounts, when compared to the monoterpenic ones, both in elderflowers and in elderberries. They represent up to 0.6% in elderflowers, with *β*-caryophyllene and α-farnesene as major sesquiterpenic components, while in elderberries, they account for up to 13% of the terpenic content, being *β*-caryophyllene and aromadendrene the major ones [31, 37]. No quantitative data for the resquiterpenic composition of

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Crop quality could be defined as a set of agronomic/commercial, organoleptic, and nutritional qualities that are variable among (1) distinct species but also among different cultivars within the same species (genetic factors); (2) different climatic conditions, such as water availability and light exposition; and (3) different agronomic conditions, such as cultivation systems, fertilization, and harvesting date [46]. Altogether, these preharvest factors may have an impact on the final quality of the elderberry fruits and flowers; however, the information about these effects is scarce. The impact of preharvest factors is often focused on parameters with direct agronomic and commercial relevance, as plant yield, fruit size, sugar content and acidity (e.g., reviews on *S. nigra* plant [18, 23]), from which some nutritional quality parameters can be inferred. However, the comprehensive impact of these parameters on the chemical composition, specially in what concerns the target molecules with determining biological properties, still remains unknown. As relevant examples in the present appraisal, the impact of preharvest factors on *S. nigra* mono and sesquiterpenic compounds is still in the beginning and the

fresh flowers and berries is available in literature.

**Figure 3.** Main monoterpenic components from *S. nigra* flowers and berries.

**4.1. Preharvest impact**

**4. Factors that modulate mono and sesquiterpenic profile**

**Figure 2.** GC × GC–ToFMS chromatogram contour plots from fresh elderflowers (A) and fresh ripe elderberries (B). The chromatographic spaces corresponding to monoterpenic and sesquiterpenic compounds are highlighted.

As evidenced in **Table 1**, of the 64 volatile terpenic compounds reported from elderflowers, 40 are oxygen-containing structures. As shown in **Figure 2**, the peak intensities of the monoterpenic metabolites predominate, representing up to 99 and 77% of the overall elderflowers and elderberries terpenic content, respectively [31, 37]. Linalool oxide (in the pyranoid form) is a major component from fresh elderflowers, accounting for up to 87% (relative to the overall GC peak area) [31]. Other authors reported that hotrienol (14%, w/w), rose oxide (5%, w/w), linalool (4%, w/w), and linalool oxide (furanic forms, 3%, w/w) were the major monoterpenic metabolites from dried elderflowers [42] (chemical structures illustrated in **Figure 3**).

Regarding ripe elderberries, limonene and *p*-cymene are reported as the major monoterpenic components (**Figure 3**). Along with limonene (2.2–9.9 μg/kg of fresh berries), other authors reported as major components in fresh elderberries the monoterpenic compounds Comprehensive Insight into the Elderflowers and Elderberries (*Sambucus nigra* L.) Mono… http://dx.doi.org/10.5772/intechopen.77291 67

**Figure 3.** Main monoterpenic components from *S. nigra* flowers and berries.

linalool (1.2–128.9 μg/kg of fresh berries) and *α*-terpineol (70.8–2699.5 μg/kg of fresh berries) (**Figure 3**) [41]. Monoterpenic compounds also prevailed in its juice, ranging from 8.9 to 77.2 ng/mL, limonene and linalool being the main monoterpenic components (**Figure 3**) [38]. Sesquiterpenic compounds are present in lower amounts, when compared to the monoterpenic ones, both in elderflowers and in elderberries. They represent up to 0.6% in elderflowers, with *β*-caryophyllene and α-farnesene as major sesquiterpenic components, while in elderberries, they account for up to 13% of the terpenic content, being *β*-caryophyllene and aromadendrene the major ones [31, 37]. No quantitative data for the resquiterpenic composition of fresh flowers and berries is available in literature.
