3.2. Essential oils
The aerial parts of H. heterophyllum were recorded to contain
0.09±0.01%, 0.087±0.006%, 0.05±0.00% and 0.077±0.02% essential oil
for BF1, BF2, 50%F, and FF stages, respectively (Figure 4). Essential
oil contents recorded in the BF1, BF2 and FF stages did not show
statistically (p ≤0.05) significant differences. However, the
highest and lowest essential oil content was obtained from BF1 and 50%F
stage, respectively. In the previous study, it was stated that
hydrodistillation of the dried aerial parts of H. heterophyllumyielded 0.09% of the essential oil (Cakir et al., 2004). The amount of
the essential oil from aerial parts of H. aucheri , H.
montbretii , H. kazdaghensis , and H. perforatum was
0.28%, 0.22%, 0.17% and 0.23% in the before flowering, 0.27%,
0.20%, 0.24% and 0.33% in the beginning of flowering, 0.33%,
0.23%,0.26% and 0.37% in the full flowering, 0.02%, 0.03%, 0.02%,
and 0.05% in the capsule during, respectively (Pasa, 2013). In the fourHypericum species, the highest essential oil ratio was obtained
from the plants harvested in full flowering period. In our study, the
highest rate of essential oil was recorded in BF2, followed by FF.
The chemical components of H. heterophyllum essential oils from
four different development stages was given in Table 6 The total of 15,
15, 13, and 16 components representing 92.19%, 80.08%, 90.13%, and
84.24% of the total essential oils were detected in the BF1, BF2,
50%F, and FF stages, respectively.
In this study, germacrene-D, bicyclogermacrene, δ-cadinene, spathulenol,
α-guaiene, and valencene having significant biological activities were
found to be main components of essential oils obtained from different
ontogenetic stages of H. heterophyllum (Table 6 and Table 8). In
the study carried out by Cakir et al (2004), in the essential oil ofH. heterophyllum , 35 compounds, representing 99.4% of the total
essential oil, were determined, and isocaryophyllene (17.1%), α-pinene
(11.6%), δ-cadinene (9.5%), γ-muurolene (8.2%), γ-cadinene (5.5%),
n-decane (5.8%), and β-Caryophyllene (4.5%) were recorded as major
compounds in this essential oil. Although there is similarity between
these findings and present study, there are some differences. Essential
oil components have been reported to be affected by many intrinsic
(genetic, plant origin, type of plant part, stage of development or
seasonal sampling period etc.) and extrinsic factors (environmental
factors such as climate and habitat conditions, sowing date, cultivation
conditions, and postharvest techniques such as drying methods and
extractions, distillation time, and conditions of analysis) (Moghaddam
& Mehdizadeh, 2017).
The variation of the main components has been given in Figure 5. The
highest concentrations of germacrene-D were recorded in the BF1, 50%F,
and BF2 stages, respectively. This component showed a significant
decrease by average 3 times in the FF stage. Bicyclogermacrene reached
the maximum concentration in the BF1 stage. The amount of this compound
reduced approximately to half in the 50%F and BF2 stages, and it was
not detected in the FF stage. Although the highest amount of δ-cadinene
was recorded in the FF period, similar rates were obtained in BF1 and
50%F stages. But a decrease of about 7% was observed in the BF2 stage.
The highest ratio of spathulenol was recorded in the 50%F stage,
followed by the BF2 stage. The lowest ratio was obtained from BF1 stage.
The amount of valencene being among the minor components in the BF1, BF2
and 50%F stages was found to be 9.76 % in the FF stage. α-Guaiene was
detected only in the essential oil in the FF stage (Table 6).
Significant differences in the concentrations of the main components ofH. heterophyllum essential oil were determined according to the
developmental stages. A similar situation was observed in the minor
components of the essential oil such as β-caryophyllene, α-humulene,
aromadendrene, viridiflorol, globulol, salvial-4(14)-en-1-one,
isospathulenol, tau-muurolol, α-amorphene, and α-cadinol (Table 6).
In terms of the effect of ontogenetic variability on essential oil
components, the full flowering stage was more effective in H.
perforatum and H. aucheri species (Pasa, 2013). The amount of
essential oil and the changes in its chemical composition during
ontogenesis are specific to each taxon (Németh, 2005). The findings from
previous studies showed that there may be similarities and differences
in the its chemical composition and amount of essential oil of various
species at different phonological stages or harvesting time inMenhta aquatic L. (Andro et al., 2013), Origanum vulgareL. (Chauhan et al., 2013), Ocimum basilicum L. (Lemberkovics et
al., 1998), Cuminum cyminum L. (Moghaddam et al., 2015), andThymus capitatus L. (Casiglia et al., 2015).
The timing of the harvest or collection of the herbal crops is one of
the most important factors affecting the quality of the essential oils
obtained from them. The therapeutic properties of herbal drugs are
related to the bioactive substances they contain. The amount of
bioactive substances composed of secondary metabolites shows significant
changes according to the development stage of plant. For this reason,
the drug producer must first of all know the bioactive substance
exchange of the medicinal and aromatic plant very well and gather the
drug which is the richest of the active substances (Baydar, 2013).
Essential oils are the most important of other volatile secondary
metabolites derived from medicinal and aromatic plants. Therefore,
obtaining high essential oil yields with the most desirable chemical
compounds is very important for industrial purposes. The selection of
appropriate phonological stage can be help researchers to fulfill this
requirement (Afshari & Rahimmalek, 2018).
In the dry capsules, 0.087±0.015% essential oil was detected. In the
obtained essential oil, 23 components were determined, which make up
99.50% of the essential oil. α-Pinene had the highest value with
33.28% among these components. This component was followed by β-pinene
(17.80%), β-myrcene (9.30%), limonene (5.95%), and cis-ocimene
(5.45%), respectively. In addition, trans-caryophyllene, α-terpineol,
carvacrol, copaene, verbenone and trans- β -ocimene have been recorded
as other important components (Table 7). No studies on the capsule
essential oil content and composition of H. heterophyllum have
been found in the literature review. The essential oils examined were
found to be rich in the major components that exhibit various biological
activities (Table 8).