# The Effect of Antagonist Abiotic Stress on Bioactive Compounds from Basil (_Ocimum basilicum_)
## 1 Introduction  
Basil (_Ocimum basilicum_), also known as sweet basil, is a medicinal plant from the _Lamiaceae_ family. Basil plants are being used in various industries, including pharmaceutical, cosmetics, food, and in religious ceremonies [1, 2]. Due to its remarkable properties, i.e., antidiabetic, wound healing, antioxidant, radiation protective, immunomodulatory, antifertility, anti-inflammatory, antimicrobial, antistress, and anticancer activities, basil could be exploited in traditional medicine [1, 3, 4, 5]. The chemical composition of basil plants depends on the variety, geographic origin, time of harvesting, and growth conditions [6, 7]. Basil's essential oil composition depends on the cultivar [8]. For example, _Ocimum basilicum_ var. _purpureum_ essential oil has mainly methyl chavicol (57.3%), while the principal chemical component in _Ocimum basilicum_ var. _thysiflora_ is linalool (68%) [7]. In a study that included 38 different genotypes of _Ocimum basilicum_ L, it was shown that seven chemotypes--high-linalo, linalool--eugenol, methyl chavicol, methyl chavicol--linalool, methyl eugenol--linalool, methyl cinnamate--linalool, and bergamotene--could be detected [9]. In another study with 27 cultivars, only five chemotypes were proposed: eugenol--linalool, linalool, estragole--linalool, methyl cinnamate, and estragole [10]. The composition of volatile organic compounds (VOCs) emitted from plants can be quite different from the chemical composition of essential oils [6, 11]. VOCs are emitted asa response to abiotic and biotic stress [6; 11; 12]. The VOCs that can be found in basil plant emissions are monoterpenes (\(\beta\)-myrcene, \(\beta\)-pinene, _cis_ and _trans_\(\beta\)-ocimene, camphene, limonene, camphor, _cis_-\(\beta\)-terpineol, \(\beta\)-linalool, terpinen-4-ol, \(\alpha\)-terpineol, bornyl acetate), sesquiterpenes (\(\beta\)-elemene, \(\alpha\)-bergamonte), phenylpropanoids (eugenol, methyl eugenol, eugenol acetate, methyl chavicol), and fatty acid-derivative esters (octyl acetate, 1-octenyl acetate) [6; 13]. Several studies conducted on basil plants found that their major phenolic compounds are: rosmarinic, chicoric, caffe, cafratz, 4-hydroxybenzoic, salvianic acid, quercetin, kaemfred, and anthocyanins [14; 15; 16]. In recent years, more and more studies support the fact that climate can change rapidly [17; 18] and can alter biological diversity and crop production. Environmental stress can be defined as changes in growth conditions within the plant's natural habitat [19]. In general, environmental stress can be divided into two types: biotic (bacteria, fungi, and insects) and abiotic. Abiotic stress, such as water availability (drought and flooding), temperature, heavy metals, salinity, and light intensity, can influence plant development and crop yield [19]. The tolerance to abiotic stress, respectively drought and flooding, can be observed in all plants, but the tolerance level differs from species to species [20]. Plants respond to drought and flooding by various molecular genetic expressions, biochemical metabolism, and physiological processes [21]. In case of water deficiency, the plants can produce osmotic adjustments, increase cell wall elasticity to preserve tissue turigidity [21], and increase side chains of the pectic polymers [22]. A decrease in cell wall thickness was noticed in Black spruce under drought stress [23]. Another response to limit the effect of drought stress is restricting the leaf transpiration surface [24]. The impact of drought stress can be modified by applying a reduced intensity of light [25]. The importance of abiotic stresses to agriculture can be easily observed, considering that abiotic factors significantly limit crop yield worldwide and reduce productivity [26]. Many lands are exposed to abiotic stresses (e.g., drought, flooding, changes in temperature, light intensity, salinity). This fact is expected to increase due to climate change and anthropogenic activities [19].