**2. Chemical composition of EOs**

#### **2.1 EOs from algae**

Algae extracts are proven to be rich sources of metabolites with a wide range of biological activities such as anti-microbial, anti-oxidant, and pharmaceutical activities [13], thus, several extraction methods have been performed to preparation of algal extract [14] and evaluated their nutritional and pharmacological applications, however, a few number of studies focused on the characterization and composition of EOs from algal extracts. Hence, some scientific efforts have been dedicated to study essential oil composition of algae extracts. The GC-MS analysis of chemical composition shows the presence of different groups of essential oil in micro and macroalgae.

*Asparagopsis taxiformis* is species of red algae (Rhodophyta) which its EOs consist of bromine and iodine-containing haloforms with the smaller amount of other halogenated methanes and several halogenated ethanes, ethanols, formaldehydes, acetaldehydes, acetones, 2-propanols, 2-acetoxypropanes, propenes, epoxypropanes, acroleins, butenones, halogenated acetic and acrylic acids [15]. Two other red seaweeds (Rhodophyta) *Laurencia obtusa* and *Laurencia obtusa* var. pyramidata are also rich in EOs and 28 components in the oil of *L. obtusa* and 27 components in the oil of *L. obtusa* var. *pyramidata* were identified and 2,6-dimethyl-4-oxa-endotricyclodecane was the highest account in both red algae [16].

In addition, the brown macroalgae (Phaeophyta) such as *Colpomenia sinuosa*, *Dictyota dichotoma*, *Dictyota dichotoma* var. *implexa*, *Petalonia fascia* and *Scytosiphon lomentaria* are rich in the EOs. The GC/MS analysis discovered the components including hydrocarbons, terpenes, acids, phenols, sulfur-containing compound, aldehydes, naphthalene skeleton and alcohols in *C. sinuosa*, *D. dichotoma*, *D. dichotoma* var. *implexa*, *P. fascia* and *S. lomentaria*. Among these brown seaweeds, *S. lomentaria* is rich in crown ether (18-crown-6-ether). Moreover, the presence of dihexylsulfide in essential oil profile of *C. sinuosa* revealed the potential of *C. sinuosa* for supplying the rare sulfur-containing compound in seaweeds [17]. Ref. [17] discovered the eight (58.41%) for *D. dichotoma* var. *implexa*, 12 (83.53%) for *D. dichotoma*, 4 (91.71%) for *P. fascia*, 6 (87.89%) for *S. lomentaria* and 14 (74.17%) compounds for *C. sinuosa* in total composition of their essential oil.

Recently, there is interest in the microalgae as well as macroalgae for development of EOs. For this respect, the 50 total compositions of the EOs from *Dunaliella salina* extract were identified and octadecanoic acid, methyl ester (27.43%), hexadecanoic acid, methyl ester (Cas) methyl palmitate (24.82%), 9,12,15-octadecatrienoic acid, ethyl ester, (Z,Z,Z) (7.39%), octadecanoic acid (5.03%), pentadecanoic acid (3.60%) were detected as major compounds [18].

**193**

**Table 1.**

*Application of Essential Oils for Shelf-Life Extension of Seafood Products*

Furthermore, the other various microalgae such as *Stichococcus bacillaris*, *Phaeodactylum tricornutum*, *Microcystis aeruginosa* and *Nannochloropsis oculata* extracts exhibited the antileukemic effects which was related to their EOs. According to [6] findings, the essential oil profile of *S. bacillaris* consist of

N-methoxy-N-methylacetamide, 9-octadecenamide, (Z)- and pentan-1,3 dioldiisobutyrate, 2,2,4-trimethyl-compounds. While, *P. tricornutum* essential oil include pentan-1,3-dioldiisobutyrate, 2,2,4-trimethyl-compound. Tricosane (CAS) n-Tricosane was detected only in *P. tricornutum* extract. Further, cyclopropanecaronic acid,-2-phenyl, ethyl ester (E-), molybdenum, bis[(1,2,3,4,5-eta)-1,3 bis(1,1-dimethylethyl)-2,4-cyclopentadien-1-yl]di-mu-carbonyldicarbonyldi-, (mo-mo), 9-octadecenoic acid (Z)-, methyl ester and 9-octadecenoic acid, methyl ester (CAS) methyl octadec-9-enoate were detected only in *M. aeruginosa* extract. Acetic acid 3-isopropyl-8,10,14-trimethyl-16-phenyl-1,2,3,5,6,7,8,9,10,11,12,14- and

2,6-dihydroxybenzoic acid 3TMS were detected only in *N. oculata* extract.

So many researches inquired into the chemical composition of the EOs obtained from various sources including *Thymus ulgaris, Nigella sativa, Achillea millefolium, Curcuma zedoaria*, *Rosmarinus officinalis* etc. A summary of these investigations is reported in **Table 1**. In an outstanding study, the essential oil composition of thyme (*Thymus ulgaris* L*.*) was investigated by capillary GC/MS evaluation method. The effect of vegetative cycle on the variation of EOs chemical composition was looked over, as well. Generally, the oil was had high amounts of monoterpene

**EOs sources Major components References** *A. taxiformis* Bromine and iodine-containing haloforms [15]

*S. lomentaria* Crown ether (18-crown-6-ether) [17] *C. sinuosa* Dihexylsulfide [17]

*D. salina* Octadecanoic acid, methyl ester, hexadecanoic acid, methyl ester

*Nigella sativa* Thymoquinone, *p*-cymene, carvacrol, 4-terpineol, t-anethole, and sesquiterpene longifolene

*N. oculata* Acetic acid 3-isopropyl-8,10,14-trimethyl-16-

3TMS

β-pinene

*Some investigations performed to investigate the chemical composition of EOs.*

2,6-Dimethyl-4-oxa-endo-tricyclo decane [16]

[18]

[6]

[20]

[21]

(Cas) methyl palmitate, 9,12,15-octadecatrienoic acid, ethyl ester

phenyl-1,2,3,5,6,7,8,9,10,11,12,14- and 2,6-dihydroxybenzoic acid

Camphor, camphene, α-pinene, 1, 8-cineole, borneol, and

Carvacrol, thymol, *p*-cymene, and γ-terpinene [19]

*ar-*turmerone, turmerone, and curlone [22]

1,8-cineole, α-pinene, camphor, and camphene [24]

5,6-dihydroergosterol, ergost-7-en-3-ol, (3beta)-(CAS)5,6,22,23-tetrahydroergosterol,

*DOI: http://dx.doi.org/10.5772/intechopen.86574*

**2.2 EOs from other plants**

*L. obtusa* and *L. obtusa* var. pyramidata

Thyme (*Thymus ulgaris* L*.*)

Flowering Thyme (*Thymis vulgaris* L.)

Turmeric (*Curcuma* 

*longa* L.)

Rosemary (*Rosmarinus officinalis* L.) *Application of Essential Oils for Shelf-Life Extension of Seafood Products DOI: http://dx.doi.org/10.5772/intechopen.86574*

Furthermore, the other various microalgae such as *Stichococcus bacillaris*, *Phaeodactylum tricornutum*, *Microcystis aeruginosa* and *Nannochloropsis oculata* extracts exhibited the antileukemic effects which was related to their EOs. According to [6] findings, the essential oil profile of *S. bacillaris* consist of 5,6-dihydroergosterol, ergost-7-en-3-ol, (3beta)-(CAS)5,6,22,23-tetrahydroergosterol, N-methoxy-N-methylacetamide, 9-octadecenamide, (Z)- and pentan-1,3 dioldiisobutyrate, 2,2,4-trimethyl-compounds. While, *P. tricornutum* essential oil include pentan-1,3-dioldiisobutyrate, 2,2,4-trimethyl-compound. Tricosane (CAS) n-Tricosane was detected only in *P. tricornutum* extract. Further, cyclopropanecaronic acid,-2-phenyl, ethyl ester (E-), molybdenum, bis[(1,2,3,4,5-eta)-1,3 bis(1,1-dimethylethyl)-2,4-cyclopentadien-1-yl]di-mu-carbonyldicarbonyldi-, (mo-mo), 9-octadecenoic acid (Z)-, methyl ester and 9-octadecenoic acid, methyl ester (CAS) methyl octadec-9-enoate were detected only in *M. aeruginosa* extract. Acetic acid 3-isopropyl-8,10,14-trimethyl-16-phenyl-1,2,3,5,6,7,8,9,10,11,12,14- and 2,6-dihydroxybenzoic acid 3TMS were detected only in *N. oculata* extract.
