| || || Materia medica, Vegetable -- Fiji|
| || || Screening for acetylcholine esterase inhibitory and anti-oxidant properties in selected Fijian Medicinal Plants |
Author: Chand, Ranish Nitesh
Institution: University of the South Pacific.
Subject: Acetylcholinesterase -- Therapeutic use -- Fiji, Antioxidants -- Therapeutic use -- Fiji, Materia medica, Vegetable -- Fiji
Call No.: Pac QP 609 .A25 C43 2016
Copyright:Under 10% of this thesis may be copied without the authors written permission
Abstract: Alzheimer’s disease (AD) is a progressive, neurodegenerative disorder, a form of dementia that affects mostly elderly people. Symptoms of AD include deterioration of intellectual functions such as memory and learning. An enormous social and economic burden is placed on the society due to its debilitating nature of the disease. It is appalling that there is no cure for the disorder and the available treatments only delay the progression of the disease or provides relief for short period of time. Inhibition of the enzyme, acetylcholinesterase (AChE) is still considered to be the main therapeutic strategy against AD. Many plant derived phytochemicals display AChE inhibitory activity in addition to the currently approved drugs for AD, yet further research is required to discover more effective and cheaper drugs free from side effects. In the present study, Ellman’s assay was used to screen for acetylcholinesterase inhibitors (AChEI) from decoction and ethanol extracts of Fijian medicinal plants. These plants were selected based on the interview about the Fijian medicinal knowledge; that is, the traditional uses that might be associated with acetylcholinesterase inhibition. Thirteen plant species belonging to Melastomataceae, Asteraceae, Apiaceae, Rutaceae, Goodeniaceae, Loganiaceae, Araliaceae, Solanaceae, Polygonaceae, Zingiberaceae and Anacardiaceae families were tested at 0.2 mg/mL, 0.4 mg/mL, 0.6 mg/mL, 0.8 mg/mL, 1.0 mg/mL, 1.5 mg/mL and 2.0 mg/mL concentrations. The most active plants were: Micromelum minutum (IC50 = 4.57 mg/mL), Ageratum conyzoides (IC50 = 5.57 mg/mL), Neuburgia collina (IC50 = 5.74 mg/mL), and Polygonum perfoliata (IC50 = 9.24 mg/mL) for their potent AChE inhibitory activity. Antioxidant activities of these plants were also assessed using the 2,2-diphenyl-1- picryl-hydrazyl (DPPH) scavenging assay. Among the extracts used, antioxidant activity was most significant for Clidemia hirta with an IC50 value of 0.64 mg/mL where even more active compounds than ascorbic acid (IC50 = 1.33 mg/mL) should be present. These plant extracts could prove leads to safer and better candidates for the future selection of drugs against this devastating disease.
| || || Whitefly control and anti-microbiological activities of essential oils from medicinal plants found in Fiji Islands|
Author: Chand, Ravneel Rajneel
Institution: University of the South Pacific.
Subject: Materia medica, Vegetable -- Fiji, Essences and essential oils -- Therapeutic use -- Fiji, Medicinal plants -- Fiji
Call No.: Pac RS 185 .F5 C43 2016
Copyright:10-20% of this thesis may be copied without the authors written permission
Abstract: A variety of plant materials contain essential oils that have extensive bioactivity properties. These properties are attributed to the chemical composition of essential oils. In the current research, chemical composition, whitefly control and antimicrobiological activities of essential oils from five medicinal plants found in Fiji; Cananga odorata (Makasoi), Murraya koenigii (L) Spreng (Curry leaves), Euodia hortensis forma hortensis (Uci), Ocimum tenuiflorum L (Tulsi) and Cymbopogon citratus (Lemon grass) were investigated. Firstly, the selected essential oils were analysed using Gas Chromatography Mass Spectrometry (GC-MS). The identified compounds were classified into groups. For the biological activities, different concentrations of essential oil solutions (0.25%, 0.5% and 5% (v/v)) were subjected to whitefly (Aleurodicus dispersus Russell) control activities in the form of fumigant and repellent test. Essential oils from O. tenuiflorum L were found to be best fumigant agents (100% mortality was achieved at 3 hours after exposure). The significant differences in the mortality for all the tested time (3, 6, 9, 12 and 24 hours) were only shown by O. tenuiflorum L and C. citratus essential oils, as the p<0.05 (5% level of significance). For the repellent test, none of the essential oils obtained 100% repellency based on Repellency index (RI%), however C. citratus and M. koenigii (L) Spreng were found to show the best repelling properties (RI%= 52, 52) compared to the other studied essential oils. In addition, the essential oils exhibited a very interesting antimicrobial profile when tested against five different bacteria and fungi at different concentrations (0.25%, 0.5%, 5%, 25%, 50% and 100% (v/v)). The essential oils from O. tenuiflorum L were considered to have strong antimicrobial properties as it showed the inhibition effect to all test bacteria and fungi. The trends in the chemical constituents of essential oils revealed that the phenolic and alcoholic compounds were major groups of contributors for the tested activities. Thus, these data suggested that essential oils from selected medicinal plants found in Fiji have potential to be employed in pesticide or anti-microbiological activities.