This study was designed to assess the antioxidant, antidiabetic and antihypertensive effects of essential oils from A. melegueta and A. danielli seeds. The essential oils were extracted via hydrodistillation, dried with anhydrous Na2SO4 and characterized using gas chromatography-mass spectrometry (GC-MS). Antioxidant properties and inhibition of some pro-oxidant induced lipid peroxidation in rats' pancreas and heart homogenates were also determined. The results revealed that eugenol, eucalyptol, α-terpineol, α-caryophyllene and β-caryophyllene were the most abundant components in A. melegueta and A. danielli seeds. The essential oils inhibited α-amylase, α-glucosidase and angiotensin-I-converting enzyme in vitro. A.melegueta oil showed a higher α-amylase and α- glucosidase inhibitory activities with EC50 values of 139.00 µL/mL and 91.83 µL/mL respectively than A. danielli. However, A. danielli oil (EC50 = 48.73 µL/mL) showed the highest ACE inhibitory acivity. The highest NO radical scavenging ability was observed in A. melegueta oil while A. danielli had the highest OH radical scavenging and Fe2+- chelating ability. Furthermore, both essential oils inhibited SNP and Fe2+- induced lipid peroxidation in rats' pancreas and heart respectively in a dose dependent manner. This study reveals the biochemical principle by which essential oils from A. danielli and A.melegueta seed elicits their therapeutic effects on type-2 diabetes and hypertension (1).

Patients with chronic diseases such as cardiovascular diseases, chronic respiratory diseases, and neurological diseases have been shown to benefit from treatments such as aromatherapy in addition to medication. Most chronic diseases are caused by chronic inflammation and oxidative stress as well as harmful factors. Eucalyptol (1,8-cineole), a terpenoid oxide isolated from Eucalyptus species, is a promising compound for treating such conditions as it has been shown to have anti-inflammatory and antioxidant effects in various diseases, including respiratory disease, pancreatitis, colon damage, and cardiovascular and neurodegenerative diseases. Eucalyptol suppresses lipopolysaccharide (LPS)-induced proinflammatory cytokine production through the action of NF-κB, TNF-α, IL-1β, and IL-6 and the extracellular signal-regulated kinase (ERK) pathway, and reduces oxidative stress through the regulation of signaling pathways and radical scavenging. The effects of eucalyptol have been studied in several cell and animal models as well as in patients with chronic diseases. Furthermore, eucalyptol can pass the blood-brain barrier and hence can be used as a carrier to deliver drugs to the brain via a microemulsion system. In summary, the various biological activities of eucalyptol such as its anti-inflammatory and antioxidant properties, as well as its physicochemical characteristics, make this compound a potentially important drug for the treatment of chronic diseases (2).

Short-term cigarette smoke (CS) exposure does not cause emphysema; however, some pathogenesis hallmarks are maintained, such as oxidative stress and inflammation. This study aimed to test the efficacy of eucalyptol against short-term CS exposure in mice. C57BL/6 mice were exposed to 12 cigarettes per day for 5 days (CS group). The control group was exposed to sham smoking. Three groups of mice exposed to CS were treated to different concentrations of eucalyptol (1, 3, 10 mg/mL) via inhalation (15 min/daily) for 5 days (CS + 1 mg, CS+3 mg and CS+10 mg groups). CS group and control one were sham treated by using vehicle. The anti-inflammatory and antioxidant effects of eucalyptol were assessed 24 h after the last CS exposure by determining cell counts, measuring cytokine production and performing western blotting, biochemical and histological analyses. Eucalyptol at 3 mg/mL and 10 mg/mL concentrations reduced total leukocyte numbers compared to the CS group (p < 0.001), while macrophage numbers were reduced at all concentrations (p < 0.001). Myeloperoxidase, used as neutrophil marker, was reduced at 3 mg/mL (p < 0.01) and 10 mg/mL (p < 0.05) concentrations. Eucalyptol reduced cytokine levels (IL-1β, IL-6 and KC) at 3 mg/mL and 10 mg/mL concentrations (p < 0.01) compared to the CS group. The exception was TNF-α, with a reduction only at 10 mg/mL of eucalyptol compared to the CS group (p < 0.001). Additionally, eucalyptol decreased the NF-kappa B p65 subunit at 3 mg/mL and 10 mg/mL compared to the CS group (p < 0.01). Regarding oxidative stress, eucalyptol reduced reactive oxygen species, superoxide dismutase, catalase and malondialdehyde, mainly at 3 mg/mL and 10 mg/mL concentrations compared to the CS group (at least p < 0.05), parallel to reduced glutathione levels at the same concentrations (p < 0.001). Furthermore, treatment with eucalyptol attenuated CS-induced histopathological alterations. Collectively, these results indicate that eucalyptol acts through a mechanism involving decreased oxidative stress, inflammation and the NF-kappa B p65 subunit against CS-induced acute lung inflammation. Thus, eucalyptol may be a potential agent in the treatment of pulmonary inflammation caused by CS in humans (3).

References_______________________________

(1) Essential Oil Composition, Antioxidant, Antidiabetic and Antihypertensive Properties of Two Afromomum Species.
Adefegha SA, Olasehinde TA, Oboh G.
J Oleo Sci. 2017 Jan 1;66(1):51-63. doi: 10.5650/jos.ess16029.

(2) Eucalyptol and Its Role in Chronic Diseases.
Seol GH, Kim KY.
Adv Exp Med Biol. 2016;929:389-398.

(3) Eucalyptol attenuates cigarette smoke-induced acute lung inflammation and oxidative stress in the mouse.
Kennedy-Feitosa E, Okuro RT, Pinho Ribeiro V, Lanzetti M, Barroso MV, Zin WA, Porto LC, Brito-Gitirana L, Valenca SS.
Pulm Pharmacol Ther. 2016 Dec;41:11-18. doi: 10.1016/j.pupt.2016.09.004.

Eucalyptol is a natural component, terpenoid oxide or monoterpene (also called 1,8-cineole) that is mainly obtained from the plant Eucalyptus (Eucalyptus globulus) belonging to the Myrtaceae family.

1,8-Dihydroxy-10-carboxy-p-menthane, 2-hydroxy-cineole and 3-hydroxy-cineole are the main metabolites of eucalyptol.

It is also found in all mint species and in spices such as Aframomum melegueta and Aframomum danielli.

Industrially it appears as a colourless to yellowish liquid. Stable. Inflammable. Incompatible with acids, bases and strong oxidising agents.

What it is used for and where

Medical

Included in cough mouthwashes, it controls hypersecretion in the airways and asthma through the inhibition of anti-inflammatory cytokines. 

The most interesting ingredients, from a health point of view, of Eucalyptus are mainly alkaloids, flavonoids, pigments, phenolics, terpenes, amides, steroids and essential oils. Recent studies have shown its antimicrobial effects against bacterial, fungal, parasitic and viral agents (1).

Methanol extract (8:2) has shown significant anti-inflammatory activity through membrane stabilisation and other processes involving protein denaturation (2).

Another interesting application of eucalyptus essential oil is its larvicidal and insecticidal potential and can therefore be used in the community in artificial water bodies as an eco-friendly vector control measure in the era of increasing resistance to chemical insecticides (3).

The data emerging from this study clarify other health-oriented characteristics of the use of the aqueous leaf extract of Eucalyptus globulus that may play an important role as an antihypertensive agent to reduce the burden of cardiovascular complications (4).

Cosmetics

Antiseptic and healing agent.

Food

Flavouring at low levels (0.002%) in meat products, bakery products, confectionery.

The most relevant studies on this ingredient have been selected with a summary of their contents:

Eucaliptolo studies

Appearance	Yellowish liquid
Boiling Point	174.0±8.0°C at 760 mmHg
Melting Point	1.5ºC
Flash Point	50.9±15.3°C
Density	0.9±0.1 g/cm3
Vapor Pressure	1.6±0.3 mmHg at 25°C
Refraction Index	1.461
PSA	9.23000
LogP	2.82
Specific gravity	0.920－0.925（20℃）
Refractive index	1.4550－1.4600（20℃）
Optical rotation	-0.5°—﹢0.5°（20℃）
Solubility	1:5 / 60% alcohol solution
Chemical Safety

• Molecular Formula   C₁₀H₁₈O
• Molecular Weight  154.25
• Exact Mass    154.135757
• CAS   470-82-6
•  UNII    RV6J6604TK
• EC Number   207-431-5
• DSSTox Substance ID  DTXSID4020616
• IUPAC  1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane
• InChl=1S/C10H18O/c1-9(2)8-4-6-10(3,11-9)7-5-8/h8H,4-7H2,1-3H3
• InChl Key      WEEGYLXZBRQIMU-UHFFFAOYSA-N
• SMILES  CC1(C2CCC(O1)(CC2)C)C
• MDL number  MFCD00167977
• PubChem Substance ID    24893017
• ChEBI  27961
• RTECS  OS9275000
• FEMA    2465
• JECFA    1234
• Beilstein     105109
• NCI    C107375    C65603    C76772
• RXCUI    21116    
• NSC      760388     6171
• UN    1993

Synonyms:

• Cineole
• 1,8-cineole
• 1,3,3-Trimethyl-2-oxabicyclo[2.2.2]octane
• 1,8-Epoxy-p-menthane

References____________________________________________________________________

(1) Ghasemian A, Eslami M, Hasanvand F, Bozorgi H, Al-Abodi HR.  Eucalyptus camaldulensis properties for use in the eradication of infections.  Comp Immunol Microbiol Infect Dis. 2019 Aug;65:234-237. doi: 10.1016/j.cimid.2019.04.007.

(2) Ashour RMS, Okba MM, Menze ET, El Gedaily RA.  J  Eucalyptus Sideroxylon Bark Anti-inflammatory Potential, Its UPLC-PDA-ESI-qTOF-MS Profiling, and Isolation of a New Phloroglucinol.  Chromatogr Sci. 2019 Jul 1;57(6):565-574. doi: 10.1093/chromsci/bmz029.

(3) Kaura T, Mewara A, Zaman K, Sharma A, Agrawal SK, Thakur V, Garg A, Sehgal R. Utilizing larvicidal and pupicidal efficacy of Eucalyptus and neem oil against Aedes mosquito: An approach for mosquito control.    Trop Parasitol. 2019 Jan-Jun;9(1):12-17. doi: 10.4103/tp.TP_35_18. Epub 2019 May 22.

(4)  Ajebli M, Eddouks M.  Eucalyptus globulus possesses antihypertensive activity in L-NAME-induced hypertensive rats and relaxes isolated rat thoracic aorta through nitric oxide pathway.   Nat Prod Res. 2019 Apr 10:1-3. doi: 10.1080/14786419.2019.1598992