Aromatherapy in Okinoerabu Island: Chemistry and Pharmacology of Bioactivities

Scotti L., da Silva P.R., de Andrade J.C., de Sousa N.F., Ribeiro Portela A.C., Oliveira Pires H.F., Bezerra Remígio M.C., Alves D.D., de Andrade H.H., Dias A.L., da Silva Stiebbe Salvadori M.G., de Oliveira Golzio A.M., de Castro R.D., Scotti M.T., Bezerra Felipe C.F., et. al.

Introduction: Alzheimer's and Parkinson's are neurodegenerative disorders that affect a great number of people around the world, seriously compromising the quality of life of individuals, due to motor and cognitive damage. In these diseases, pharmacological treatment is used only to alleviate symptoms. This emphasizes the need to discover alternative molecules for use in prevention. Objective: Using Molecular Docking, this review aimed to evaluate the anti-Alzheimer’s and anti- Parkinson’s activity of linalool and citronellal, as well as their derivatives. Methodology: Before performing Molecular Docking simulations, the compounds’ pharmacokinetic characteristics were evaluated. For Molecular Docking, 7 chemical compounds derived from citron- ellal, and 10 compounds derived from linalool, and molecular targets involved in Alzheimer's and Parkinson's pathophysiology were selected. Results: According to the Lipinski rules, the compounds under study presented good oral absorption and bioavailability. For toxicity, some tissue irritability was observed. For Parkinson-related targets, the citronellal and linalool derived compounds revealed excellent energetic affinity for α-Synuclein, Adenosine Receptors, Monoamine Oxidase (MAO), and Dopamine D1 receptor proteins. For Alzheimer disease targets, only linalool and its derivatives presented promise against BACE enzyme activity. Conclusion: The compounds studied presented high probability of modulatory activity against the dis- ease targets under study, and are potential candidates for future drugs.

Liu H., Liang J., Liang C., Liang G., Lai J., Zhang R., Wang Q., Xiao G.

Bergamot (Citrus medica L. var. sarcodactylis) contains different bioactive compounds, and their effects remain unclear. Therefore, the structural and bio-function of bergamot dietary fiber were investigated. A sequential extraction procedure was utilized to obtain soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) from bergamot. The main monosaccharide in SDF and IDF is arabinose. SDF had a porous structure, which enhanced the water and oil holding capacity, as well as the cholesterol and glucose adsorption capacity, which was superior to that of IDF. In db/db diabetic mice, SDF and IDF regulated glucose tolerance and controlled blood glucose levels. Reduction of serum total cholesterol, triglycerides, and low-density lipoprotein cholesterol in SDF and IDF could be observed. In summary, SDF and IDF from bergamot effectively promoted health in patients with diabetes.

Washiyama M.

Qu Y., Guo Y., Li W., Shen H., Cui J., Li J., Liu J., Wu D.

Essential oil of Coreopsis tinctoria (EOC) is a essential substance extracted from Coreopsis tinctoria with the excellent anti-oxidant effect. However, it is still unclear whether EOC can improve learning and memory impairment and its mechanism. The purpose of this study was to investigate the effect of EOC on learning and memory impairment induced by D-galactose (D-gal) in mice and reveal its mechanism. The composition of EOC was analyzed by GC-MS, and the results showed that the highest content was D-limonene. The follow-up experiments were conducted by comparing EOC with D-limonene. The aging model was established by subcutaneous injection of D-gal, and donepezil, D-limonene and EOC were given by intragastric administration. It was found that EOC and D-limonene significantly improved learning and memory impairment induced by D-gal through the Morris water maze and step-through tests. Pathological and biochemical analysis showed that the hippocampal morphologic of mice was damage and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) induced by D-gal were decreased, while the content of malondialdehyde (MDA) was increased, while EOC and D-limonene could reverse the morphological changes and reduce oxidative damage. In addition, EOC and D-limonene significantly increased body weight and organ coefficients, including liver, spleen and kidney. Moreover, EOC and D-limonene improved the expression of nuclear factor E2 related factor 2 (Nrf2) pathway and inhibited nuclear transcription factors-κB (NF-κB) pathway. In summary, the results showed that EOC and D-limonene could improve learning and memory impairment induced by D-gal through Nrf2/ NF-κB pathway. It was clear that as a mixture, EOC was better than D-limonene on improving learning and memory impairment.

Luo B., Lv J., Li K., Liao P., Chen P.

This study aimed to extract polysaccharides from Citrus medica L. var. sarcodactylis (finger citron fruits) and analyze their structures and potential bioactivities. A new polysaccharide named K-CMLP was isolated and purified by Diethylaminoethylcellulose (DEAE)-Sepharose Fast Flow and DEAE-52 cellulose column chromatography with an average molecular weight of 3.76 × 103 kDa. Monosaccharide composition analysis revealed that K-CLMP consisted of rhamnose, galactose, and glucose, with a molar ratio of 6.75:5.87:1.00. Co-resolved by methylation and two-dimensional nuclear magnetic resonance (NMR), K-CLMP was alternately connected with 1, 2-Rha and 1, 4-Gal to form the backbone, and a small number of glucose residues was connected to O-4 of rhamnose. The results of DPPH⋅ and ABTS+⋅ radical scavenging assays indicated that both crude polysaccharide Citrus medica L. var. polysaccharide (CMLP) and K-CLMP exhibited strong free-radical-scavenging properties in a dose-dependent manner. In addition, K-CMLP significantly inhibited the production of pro-inflammatory cytokines (IL-6 and TNF-α) and reactive oxygen species (ROS) in RAW 264.7 cells treated with LPS. These results provide a basis for further use as one of the potential functions of food or natural medicine.

Saito T., Nishida Y., Tabata M., Isobayashi A., Tomizawa H., Miyahara Y., Sugizaki Y.

Researchers widely apply enzyme inhibition to chemicals such as pesticides, nerve gases, and anti-Alzheimer's drugs. However, application of enzyme inhibition to odorant sensors is less common because the corresponding reaction mechanisms have not yet been clarified in detail. In this study, we propose a new strategy for highly selective detection of odorant molecules by using an inhibitor-specific enzyme. As an example, we analyzed the selective interactions between acetylcholinesterase (AChE) and limonene─the major odorant of citrus and an AChE inhibitor─using molecular dynamics simulations. In these simulations, limonene was found to be captured at specific binding sites of AChE by modifying the binding site of acetylcholine (ACh), which induced inhibition of the catalytic activity of AChE toward ACh hydrolysis. We confirmed the simulation results by experiments using an ion-sensitive field-effect transistor, and the degree of inhibition of ACh hydrolysis depended on the limonene concentration. Accordingly, we quantitatively detected limonene at a detection limit of 5.7 μM. We furthermore distinguished the response signals to limonene from those to other odorants, such as pinene and perillic acid. Researchers will use our proposed odorant detection method for other odorant-enzyme combinations and applications of miniaturized odorant-sensing systems based on rapid testing.

Washiyama M.

Sakurai K., Tamai E., Masuda Y., Urakami K., Kusuhara M.

The volatile components of kuromoji oil (Lindera umbellata Thunb.) obtained in Shizuoka Pref. were analyzed by GC/MS. Linalool, α-pinene, limonene, camphene, cis- and trans-dihydrocarvone, 1,8-cineol, 4-terpinenol, α-terpineol, piperitone, geranyl acetate, geraniol, and trans-nerolidol were identified as major components. Using enantio-MDGC-MS, the enantiomeric ratio ((R)-(-) vs (S)-(+)) of linalool in this oil was determined to be 67.8/32.2. Touch care treatment while sniffing this oil was done on cancer patients. We found that the relaxation effect persisted longer after the treatment compared to treatment without aroma.

Kumar R., Kumar R., Sharma N., Khurana N.

Myrcene (Myr) has been reported to show neuroprotective effects in cerebral ischemia. In this research work, we investigated the Myr effect on neurobehavioural, and neuropathological alteration in mice induced by Aluminium trichloride (AlCl3) and D - galactose. The administration of AlCl3 (5 mg/kg; p. o.), and D - galactose (60 mg/kg; i. p.) for 90 days in mice resulted in spatial learning and memory deficits, cognitive decline, as well as neurotoxicity. The treatments with Myr low dose (100 mg/kg), Myr high dose (200 mg/kg), donepezil (2 mg/kg), and Myr low dose + donepezil (100 + 2 mg/kg) were administered via intraperitoneal route for 30 days significantly reversed the neurobehavioral, and neuropathological effects of AlCl3 and D - galactose in mice. The results of behavioural tests such as Morris water maze, elevated plus maze, and locomotor; biochemical analysis such as malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), nitrite, and acetylcholinesterase (AChE); and ELISA tests such as mouse β - secretase (BACE), amyloid-beta peptide1-42 (Aβ1 - 42), tumor necrosis factor - α (TNF-α), interleukin - 6 (IL-6), and brain-derived neurotrophic factor (BDNF) demonstrated a significant (p < 0.05) neuroprotective effect of the Myr and donepezil co-treatments. In addition, hematoxylin and eosin staining of the cerebral cortex and hippocampus revealed eosinophilic lesions and hyperchromatic nuclei in Alzheimer's disease mice, but treatments with Myr low dose, Myr high dose, donepezil, and Myr low dose + donepezil reversed these neurodegenerative effects. Myr showed these activities by enhancing synaptic plasticity and cholinergic activity, as well as reducing oxidative damage, neuroinflammation, Aβ1-42 aggregations, and histopathological damage. Myr alone and in combination with donepezil may serve as a potential candidate for the treatment of Alzheimer's disease.

Lee K., Chu C., Chiang S.

Alzheimer’s disease (AD) is caused by excessive oxidative damage and aging. The objective of this study was to investigate the anti-dementia effect of LCP fruit powder on amyloid β (Aβ)-induced Alzheimer’s mice. The composition of LCP essential oil was determined by gas chromatography/mass spectrometry. In addition, the water maze was used to evaluate the learning and memorizing abilities of the mice. The concentrations of malondialdehyde (MDA), protein carbonyl, phosphorylated τ-protein, and the deposition of Aβ plaques in mouse brains were also assessed. The results showed that the main components of essential oils in LCP and d-limonene, neral, and geranial contents were 14.15%, 30.94%, and 31.74%, respectively. Furthermore, oral administration with different dosages of LCP significantly decreased the escape time (21.25~33.62 s) and distance (3.23~5.07 m) in the reference memory test, and increased the duration time (26.14~28.90 s) and crossing frequency (7.00~7.88 times) in the target zone of probe test (p < 0.05). LCP also inhibited the contents of MDA and the phosphor-τ-protein from oxidative stress, reduced the brain atrophy by about 3~8%, and decreased the percentage of Aβ plaques from 0.44 to 0.05%. Finally, it was observed that the minimum dosage of LCP fruit powder (LLCP, 30.2 mg/day) could prevent oxidative stress induced by Aβ and subsequently facilitate memory and learning deficits in Aβ-induced neurotoxicity and cognitively impaired mice.

Washiyama M.

Ma Q., Wei R., Yang M., Huang X., Wang F., Dong J., Sang Z.

• Ten new neolignan derivatives ( 1 – 10 ) were isolated from the fruits of Citrus medica. • Hepatoprotective and neuroprotective activities of compounds ( 1 – 24 ) were assayed. • Biogenetic pathway and structure-activity relationship were summarized and discussed. The fruit of Citrus medica L. var. sarcodactylis Swingle is a functional food with rich nutrients and medicinal values because of its content of bioactive compounds. A bioactivity-guided chemical investigation from the fruits of C. medica L. var. sarcodactylis Swingle afforded three new benzodioxane neolignans ( 1 – 3 ), three new phenanthrofuran neolignan glycosides ( 4 – 6 ), two new biphenyl-ketone neolignans ( 7 – 8 ), two new 1′,7′-bilignan neolignans ( 9 – 10 ), as well as fourteen known neolignan derivatives ( 11 – 24 ), which were isolated and characterized from the fruits of C. medica L. var. sarcodactylis Swingle for the first time. These neolignan derivatives were determined by extensive and comprehensive analyzing NMR, HR-ESI-MS, UV, IR spectral data and compared with the data described in the literature. Among them, compounds 1 – 3 and 12 – 13 exhibited moderate hepatoprotective activities to improve the survival rates of HepG2 cells from 46.26 ± 1.90% (APAP, 10 mM) to 67.23 ± 4.25%, 62.87 ± 4.43%, 60.06 ± 6.34%, 56.75 ± 2.30%, 58.35 ± 6.14%, respectively. Additionally, compounds 7 – 8 and 21 – 22 displayed moderate neuroprotective activities to raise the survival rates of PC12 cells from 55.30 ± 2.25% to 66.94 ± 3.37%, 70.98 ± 5.05%, 64.64 ± 1.93%, and 62.81 ± 4.11% at 10 μM, respectively. The plausible biogenetic pathway and preliminary structure–activity relationship of the selected compounds were scientifically summarized and discussed in this paper.

Ma L., Liu J., Lin Q., Gu Y., Yu W.

Eugenol is a naturally occurring compound that is present in a variety of plants and has previous been demonstrated to exert a number of bioactivities. However, the potential effects of Eugenol on cellular protection against oxidative stress remain poorly understood. In the present study, HEK-293 cells and the mouse fibroblast cell line NIH-3T3 cells were used as models to explore the effects of eugenol on H2O2-induced damage. Among the three natural compounds tested, namely eugenol, methyleugenol and acetyleugenol, eugenol was found to increase the transcriptional activity and expression level of nuclear factor erythroid 2-related factor 2 (Nrf2), a central regulator of cellular responses to oxidative stress, in a dose-dependent manner. The mRNA levels of Nrf2 target genes glutamate-cysteine ligase modifier regulatory subunit and glutathione S-transferase A1, were also found to be upregulated following eugenol treatment. Further study revealed that eugenol enhanced the stabilization and nuclear translocation of Nrf2. Additionally, treatment with eugenol was found to reduce intracellular ROS levels while increasing cellular resistance to H2O2, in a manner that was dependent on Nrf2. In conclusion, data from the present study suggest that eugenol is a protective agent against oxidative stress that exerts its effects through a Nrf2-dependent pathway, rendering eugenol and its derivatives to be promising candidates for the future development of antioxidants.

Luo X., Wang J., Chen H., Zhou A., Song M., Zhong Q., Chen H., Cao Y.

Finger citron (Citrus medica L. var. sarcodactylis Swingle) is a traditional Chinese herb and considered as a healthy food. Flavonoids are the major bioactive substances in Finger citron. In this study, the major flavonoids of finger citron (FFC) were purified with AB-8 macroporous resins and then three of them were identified as diosmetin-6-8-di-C-glucoside, hesperidin and diosmetin-6-C-glucoside, and other two were preliminarily inferred as limocitrol 3-alpha-L-arabinopyranosyl-(1->3)-galactoside and scutellarein 4'-methyl ether 7-glucoside by HPLC and UPLC-Q-TOF-MS. Further, their antioxidation and anti-aging activities were determined in vitro and in vivo. In vitro, chemical assays revealed that the purified FFC had strong antioxidative activity as demonstrated by its strong DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS [2,2-azinobis (3-ethyl-benzothiazoline-6-sulphonic acid) diammonium salt] radical scavenging activities and ORAC (oxygen radical absorbance capacity). In vivo, the purified FFC significantly increased the mean and maximum lifespan of caenorhabditis elegans (C. elegans) by 31.26% and 26.59%, respectively, and showed no side effects on their physiological functions. Under normal and oxidative stress conditions, purified FFC reduced the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), while increased superoxide dismutase (SOD) and catalase (CAT) enzyme activities in C. elegans. Together, we successfully identified three major substances in purified FFC of finger citron and determined the excellent anti-aging activity of FFC, which is attributed to its strong antioxidative activity and effect on homeostasis of ROS.

Adefegha S.A., Okeke B.M., Oboh G.

This research work examined and likened effect of eugenol a natural phenolic compound with butylated hydroxylanisole (BHA) and butylated hydroxyl toluene (BHT) synthetic phenolic compounds with key biomolecules [acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and monoamine oxidase (MAO)] relevant to Alzheimer's diseases (AD) in vitro. Ten millimolar each sample was prepared in a mixture of ethanol and water (1:1 v/v), and the interactions with AChE, BChE, and MAO were evaluated. Still, ferric reducing antioxidant property, ABTS radicals scavenging ability and lipid peroxidation were carried out. The results revealed eugenol, BHT, and BHA inhibited AChE, BChE, and MAO activities dose-dependently. Though, eugenol had greater inhibitory effect against AChE and BChE activities. Also, eugenol demonstrated higher antioxidant potential compared to BHT and BHA. The potent enzymatic inhibitory and antioxidant effects of eugenol indicate eugenol could be promising as an alternative food additive and neuromodulator in AD management. PRACTICAL APPLICATION: BHT and BHA are synthetic antioxidant employed industrially as food preservative. BHT and BHA are employed in food packaging, drugs, and cosmetics. Although BHT and BHA are widely in use but have been found were associated with alteration in sleeping, induced changes in brain serotonin and norepinephrine levels with increased cholinesterase activity. Endocrine disrupting effects, reproductive disorder is more side effects associated with the use of BHT and BHA. However, eugenol a natural compound found in plants compares favorably with BHT and BHA as antioxidant with many more health promoting benefits such as neuroprotective effects, antiapoptotic effects, and prevent aluminum toxicity. Eugenol being a natural antioxidant with no side effects showing more promising effects over the synthetic phenolic compounds and could be an alternative for the BHT and BHA.

Washiyama M.

Washiyama M.