## 3 _Apium_ Plants Phytochemical Composition  
The chemical composition of _Apium_ plants is remarkable. The variability of chemical compounds and the effects, which these substances induce, have been determined with 508 published articles indexed in the PubMed databases and 966 articles indexed in the Web of Science-Core Collection (Clarivate Analytics) databases. The chemical composition of _Apium_ plants differs depending on plant part (leaves, seeds or stalks), stage of harvesting, geographical region of production, type and method of preparation of essential oil, and growing conditions such as soil structure and climate [35,99]. The phytochemical composition of the _Apium_ plants according to the USDA Nutrient Database/Distribution of Nutrients (raw vegetable), is presented in Table 1.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  
The seeds of _Apium_ plants have a moisture content of 5%-11% and, generally, have the following constituents: protein (0.8%), non-volatile oil (5.8%-14.2%), volatile oil (1.5%-3%), total ash content (6.9%-11.0%), cold water extract (5.9%-12.9%), and ash insoluble in acid (0.5%-4.0%). The _Apium_ plant leaves and stalk contain, generally, moisture (80.30%-93.5%), fibers (1.4%-1.2%), fat (0.6%-0.1%), protein (0%-0.8%), mineral matter (2.1%-0.9%), iron (0.06%-0.05%), calcium (0.23%-0.3%), phosphorous (0.14%-0.4%), vitamin C (62.6 mg/100 mg), and vitamin A (5800-7500 IV) [100]. _A. gravelens_ includes phtalide glycosides, about 0.2% of furocumarins, flavonoids and flavonoid glycosides (mainly apigenin, luteolin, chrysoriol, and quercetin in combination with the respective glycosides) [101]. The _A. gravelens_ leaves contain large amounts of antioxidant molecules and are a crucial source of natural dietary flavonoids [9]. The chemical constituents of the root extracts from _A. gravelens_ var. _dulec_ contain flavonoids, antioxidants, polyacetylenes, coumarins, phthalalides (\(d\)-limonene, seliene, and other related phthalalides), neocnidilide, cridilide, Z-lingustilide, senkyonolide, linoleic acid, omega-6 fatty acid, and apiol [102]; and _Apium gravelens_ var. _rapaceum_ includes butylphthalide and \(Z\)-butylide nephthalide, cridilide, \(E\)- and \(Z\)-ligustilide, neocnidilide, and senkyonolide [36; 102]. Major active constituents of _A. gravelens_ are \(\updownarrow\)-3-\(n\)-butylphthalide, sedanolide, linoleic acid, flavonoids, phenolic compounds, and volatile oil, which are extracted from its various parts including roots, leaves, and seeds [9; 32]. It also contains undifferentiated oleic acid (0.065 g), total polyunsaturated fatty acids (0.148 g), 18:2 undifferentiated linoleic acid (0.148 g), lutein + zeaxanthin (1 mg), apigenin (2.4 mg), and quercetin (0.18 mg) per 100 g [39]. Furthermore, it contains valuable vitamins and minerals such as vitamin C, potassium, calcium, sodium, and magnesium [103]. The phytochemical screening of _Apium_ plants has quantitatively demonstrated the presence of carbohydrates, alkaloids, glycosylides, flavonoids, saponins and steroids, tannins, and the majority macro- and microelements, whereas terpen were present in small quantities or even absent. In addition, volatile oils, sesquiterpene alcohols, and fatty acid were conferred. The _Apium_ plant contains phenols and furocoumarins [104]. Celery contains 3-butiphthalide. The furanocumarins shown in Figure 1 were found in leaves.