Chemically engineered essential oils prepared through thiocyanation under solvent-free conditions: chemical and bioactivity alteration (original) (raw)
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Survey of acetylcholinesterase inhibitory activity in essential oil derived from aromatic plants
International Journal of Medicinal and Aromatic Plants, 2014
Essential oils have the strong potency to inhibit acetylcholinesterase (AChE) in their lipophilicity and small molecular size constituents. Cholinesterase inhibitory activity was determined against AChE using Ellman's colorimetric method of 29 essential oils from aromatic plants. Results revealed 5 of essential oils from Eucalyptus, Cajuput, Sweet marjoram, Camphor tree and Rosemarry showed such activity respectively. The compositions of five essential oils were also analyzed by GC-MS. We also demonstrated that the AChE inhibitory activity of the essential oil could be attributed to 1,8-cineole.
Bioactive Compounds and Essential Oils as Acetylcholinesterase Inhibitors
American Journal of Biomedical and Life Sciences, 2019
As total life expectancy increases, the prevalence of age-related diseases such as Alzheimer's is also increasing. Many hypotheses about Alzheimer's disease have been developed, including cholinergic neuron damage. Acetylcholine is a major neurotransmitter in the brain and cholinergic deficits leads to cognitive dysfunction and decline. Despite decades of research and advances in our understanding of its aetiology and pathogenesis, current pharmacotherapeutic options for AD are still very limited and represent an area of need that is currently unmet. In abnormal activation of AChE, acetylcholine will degrade rapidly, especially in the brain and this is associated with Alzheimer's disease (AD). It has been shown that theraphy with essential oils from medicinal plants can improve cognitive performance in Alzheimer's disease patients. Eugenol from these essential oils is reported to inhibit acetylcholinesterase, both in vitro and in vivo. This paper is set to Determine inhibitory/stimulatory effect of tested extracts on acetylcholine esterase (AChE) activity. The sampled out plant extracts include Thymus vulgaris, Berberis vulgaris and Calluna vulgaris with which inhibition or activation by different chemical catalysts is performed to establish their effects in the tested natural extracts. Experimental design is used where the reagents are determined and chemical reactions performed in the procedures as outlined in the methodology section. The results of the cholinergic/ anticholinergic effect of tested natural extracts are then recorded. This study reflects that most of the extracts inhibited AChE activity with berberis vulgaris showing highest inhibitory effect.
Screening of Acetylcholinesterase Inhibitory Activity in Essential Oil from Myrtaceae
Thai Journal of Pharmaceutical Sciences (TJPS), 2019
Objective: This research was to investigate acetylcholinesterase inhibitory (AChEI) activity of the essential oil from Myrtaceae and its components. Materials and Methods: The essential oils were extracted from a fresh leave of Myrtaceae plants: Eucalyptus globulus Labill (Eucalyptus), Melaleuca cajuputi Powell (Samed-Khao), Melaleuca citrina (Curtis) Dum. Cours (Bottlebrush tree), Psidium guajava Linn. (Gauva), Syzygium cumini (L.) Skeel (Wha), and Syzygium samarangense (Blume) Merr. and L. M. Perry (Chompoo Nam Dok Mai) by hydrodistillation and analyzed chemical constituent by gas chromatography. The AChE inhibition was determined based on Ellman's method. Results: The essential oil from M. citrina presented the greatest inhibitory activity (71.77 ± 2.11%) and followed by E. globulus (47.65 ± 2.26%), P. guajava (24.96 ± 2.38%), M. cajuputi (21.18 ± 0.54%), S. cumini (19.97 ± 1.10%), and S. samarangense (13.78 ± 1.52%), respectively. Alpha-pinene was found in the essential oil of 6 species. 1,8-Cineole was the main compound of the essential oil from M. citrina and acts as an active constituent on AChEI. The essential oil from M. cajuputi, S. cumini, and S. samarangense contained a small amount of α-pinene, and without 1,8-cineole, then they were less potency on AChEI. Conclusion: The essential oil containing higher amount of 1,8-cineole presented strong activity to inhibit the AChE. Moreover, there are also other constituents in the essential oils that may affect the AChEI activity and also present synergistic effect for AChEI.
Evaluation of Bioactive Compounds as Acetylcholinesterase Inhibitors from Medicinal Plants
Evidence-Based Validation of Herbal Medicine, 2015
As total life expectancy increases, the prevalence of age-related diseases such as Alzheimer's is also increasing. Many hypotheses about Alzheimer's disease have been developed, including cholinergic neuron damage. Acetylcholine is a major neurotransmitter in the brain and cholinergic deficits leads to cognitive dysfunction and decline. Despite decades of research and advances in our understanding of its aetiology and pathogenesis, current pharmacotherapeutic options for AD are still very limited and represent an area of need that is currently unmet. In abnormal activation of AChE, acetylcholine will degrade rapidly, especially in the brain and this is associated with Alzheimer's disease (AD). It has been shown that theraphy with essential oils from medicinal plants can improve cognitive performance in Alzheimer's disease patients. Eugenol from these essential oils is reported to inhibit acetylcholinesterase, both in vitro and in vivo. This paper is set to Determine inhibitory/stimulatory effect of tested extracts on acetylcholine esterase (AChE) activity. The sampled out plant extracts include Thymus vulgaris, Berberis vulgaris and Calluna vulgaris with which inhibition or activation by different chemical catalysts is performed to establish their effects in the tested natural extracts. Experimental design is used where the reagents are determined and chemical reactions performed in the procedures as outlined in the methodology section. The results of the cholinergic/ anticholinergic effect of tested natural extracts are then recorded. This study reflects that most of the extracts inhibited AChE activity with berberis vulgaris showing highest inhibitory effect.
Journal of Chromatography A, 2000
A high-performance liquid chromatography (HPLC) method with on-line coupled ultraviolet (UV), mass spectrometry (MS) and biochemical detection for acetylcholinesterase (AChE) inhibitory activity has been developed. By combining the separation power of HPLC, the high selectivity of biochemical detection, and the ability to provide molecular mass and structural information of MS, AChE inhibitors can be rapidly identified. The biochemical detection was based on a colorimetric method using Ellman’s reagent. The detection limit of galanthamine, an AChE inhibitor, in the HPLC–biochemical detection is 0.3 nmol. The three detector lines used, i.e., UV, MS and Vis for the biochemical detection were recorded simultaneously and the delay times of the peaks obtained were found to be consistent. This on-line post-column detection technique can be used for the identification of AChE inhibitors in plant extracts and other complex mixtures such as combinatorial libraries.
Planta Medica, 2008
Essential oils (EOs) are volatile compounds obtained from aromatic plants that can act as modulators of neurological systems. Several neurodegenerative diseases have been correlated with changes in the cholinergic system. Myrciaria floribunda (H. West ex Willd.) O. Berg (Myrtaceae) was chosen to investigate its biological potential for treating neurodegenerative diseases. M. floribunda fruit peel essential oil (MfEO) was collected for analysis. In this study, the chemical composition and in silico acetylcholinesterase inhibitory activities were determined. The results revealed the presence of 26 (96.86%) compounds obtained for GC/MS, of which the major compounds were the following: δ-Cadinene (26.8%), γ-Cadinene (15.69%), γ-Muurolene (6.21%), α-Selinene, α-Muurolene (6.11%) and (E)-Caryophyllene (5.54%). The ADMET analysis showed that MfEO compounds have a predicted lethal dose 628 times higher than neostigmine. The molecular docking results between the major components of MfEO and the enzyme acetylcholinesterase resulted in an average energy minimization of-6.6 Kcal/mol when the two structures coupled. In the assay of acetylcholinesterase activity, M. floribunda fruit peel oil presented an IC 50 of 0.08 μg/ml and 23 μg/ml for commercial AChE of E. electricus and that extracted from C. rhizophorae, respectively. MfEO showed enzymatic inhibition and other relevant information of bioactive compounds. This study provides the first report of the chemical composition of the fruit peel essential oil of M. floribunda and highlights the promising results obtained through in silico analysis and the inhibitory potential of AChE through an in vitro assay.
2010
A series of myricetin derivatives containing amide, thioether, and 1,3,4-thiadiazole moieties were designed and synthesized, and their antiviral and antibacterial activities were assessed. The bioassays showed that all the title compounds exhibited potent in vitro antibacterial activities against Xanthomonas citri (Xac), Ralstonia solanacearum (Rs), and Xanthomonas oryzae pv. Oryzae (Xoo). In particular, the compounds 5a, 5f, 5g, 5h, 5i, and 5l, with EC 50 values of 11.5-27.3 µg/mL, showed potent antibacterial activity against Xac that was better than the commercial bactericides Bismerthiazol (34.7 µg/mL) and Thiodiazole copper (41.1% µg/mL). Moreover, the in vivo antiviral activities against tobacco mosaic virus (TMV) of the target compounds were also tested. Among these compounds, the curative, protection, and inactivation activities of 5g were 49.9, 52.9, and 73.3%, respectively, which were better than that of the commercial antiviral Ribavirin (40.6, 51.1, and 71.1%, respectively). This study demonstrates that myricetin derivatives bearing amide, thioether, and 1,3,4thiadiazole moieties can serve as potential alternative templates for the development of novel, highly efficient inhibitors against plant pathogenic bacteria and viruses.
Chemically Engineered Extracts: Source of Bioactive Compounds
B iological research and drug discovery critically depend on access to libraries of small molecules that have an affinity for biomacromolecules. By virtue of their sustained success as sources of lead compounds, natural products are recognized as " privileged " starting points in structural space for library development. Compared with synthetic compounds, natural products have distinguishing structural properties; indeed, researchers have begun to quantify and catalog the differences between the two classes of molecules. Measurable differences in the number of chiral centers, the degree of saturation, the presence of aromatic rings, and the number of the various heteroatoms are among the chief distinctions between natural and synthetic compounds. Natural products also include a significant proportion of recurring molecular scaffolds that are not present in currently marketed drugs: the bioactivity of these natural substructures has been refined over the long process of evolution. In this Account, we present our research aimed at preparing libraries of semisynthetic compounds, or chemically engineered extracts (CEEs), through chemical diversification of natural products mixtures. The approach relies on the power of numbers, that is, in the chemical alteration of a sizable fraction of the starting complex mixture. Major changes in composition can be achieved through the chemical transformation of reactive molecular fragments that are found in most natural products. If such fragments are common enough, their transformation represents an entry point for chemically altering a high proportion of the components of crude natural extracts. We have searched for common reactive fragments in the Dictionary of Natural Products (CRC Press) and identified several functional groups that are expected to be present in a large fraction of the components of an average natural crude extract. To date, we have used reactions that incorporate (i) nitrogen atoms through carbonyl groups, (ii) sulfur by transformation of-OH and amines, and (iii) bromine through double bonds and aromatic rings. The resulting CEEs had different composition and biomolecular properties than their natural progenitors. We isolated a semisynthetic β-glucosidase inhibitor from a CEE prepared by reaction with benzenesulfonyl chloride, an antifungal pyrazole from a CEE prepared by reaction with hydrazine, and an acetylcholinesterase inhibitor from a CEE prepared through bromination. Our results illustrate how biological activity can be generated through chemical diversification of natural product mixtures. Moreover, the level of control that can be asserted in the process by judicious design and experimental choices underscores the potential for further development of CEEs in both basic research and drug discovery.
Molecules, 2020
Alzheimer's disease (AD) is a neurodegenerative disease and the most cause of dementia in elderly adults. Acetylcholinesterase (AChE) is an important beneficial target for AD to control cholinergic signaling deficit. Centella asiatica (CA) has proven to be rich with active ingredients for memory enhancement. In the present study, the chemical profiling of three accession extracts of CA namely SECA-K017, SECA-K018, and, SECA-K019 were performed using high-performance liquid chromatography (HPLC). Four biomarker triterpene compounds were detected in all CA accessions. Quantitative analysis reveals that madecassoside was the highest triterpene in all the CA accessions. The biomarker compounds and the ethanolic extracts of three accessions were investigated for their acetylcholinesterase (AChE) inhibitory activity using Ellman's spectrophotometer method. The inhibitory activity of the triterpenes and accession extracts was compared with the standard AChE inhibitor eserine. The results from the in vitro study showed that the triterpene compounds exhibited an AChE inhibitory activity with the half-maximal inhibitory concentration (IC 50) values between 15.05 ± 0.05 and 59.13 ± 0.18 µg/mL. Asiatic acid was found to possess strong AChE inhibitory activity followed by madecassic acid. Among the CA accession extracts, SECA-K017 and SECA-K018 demonstrated a moderate AChE inhibitory activity with an IC 50 value of 481.5 ± 0.13 and 763.5 ± 0.16 µg/mL, respectively from the in silico docking studies, it is observed that asiatic acid and madecassic acid showed very good interactions with the active sites and fulfilled docking parameters against AChE. The present study suggested that asiatic acid and madecassic acid in the CA accessions could be responsible for the AChE inhibitory action and could be used as markers to guide further studies on CA as potential natural products for the treatment of AD.