In vitro antioxidant and antimalaria properties of the plants chasmanthera dependens (hochst)and dictyandra arborescens (welw.)
Date
2021
Authors
Journal Title
Journal ISSN
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Publisher
Federal University of Technology, Owerri
Abstract
Crude aqueous and methanolic extracts of leaves, stem and roots of Chasmanthera dependens and Dictyandra arborescens suggested from their ethno-medicinal uses to possess antimalarial activities were evaluated for phytochemical, in vitro antioxidant, toxicity, and antimalarial activities. Phytochemicalanalyses were carried out using standard qualitative and quantitative analytical methods. In vitro antioxidant potentials of the extracts were determined by their abilities to scavenge 2, 2-diphenyl-1- picrylhydrazyl radical, nitric oxide radical and hydrogen peroxide. The antioxidant potentials were further determined by the ferric reducing antioxidant power and total antioxidant capacity using standard methods. Acute toxicity was carried out using modified Lorke’s method, sub-acute toxicity of the extracts were also determined using adult male albino rats. Antimalarial activities of the extracts were determined using male Swiss albino mice infected with Plasmodium berghei. Methanolic extracts of D.arborescens roots which showed the highest antimalarial activity was subjected to separation by silica gel column chromatography while bioassay was carried out by testing the antimalarialactivities of the fractions on male Swiss albino mice. Hexane fraction of the extract showed the highest antimalarial activity and was sub fractionated to obtain two purer eluates coded EA and EB which were characterized using Gas Chromatography – Flame Ionization Detector (GC-FID), Fourier Transform Infrared (FTIR) spectroscopy, Gas Chromatography-Mass Spectrometry (GC-MS) and Molecular docking analyses. Phytochemical screening of the extracts revealed the presence of tannins, saponins, alkaloids, cardiac glycosides, terpenoids, steroids, phenols, flavonoids, oxalate and phytate in varying amounts. The phytochemicals were more in the methanolic extracts than in the aqueous extracts. Scavenging of DPPH, nitric oxide, H2O2 radicals, reducing power ability and total antioxidant activity were concentration-dependent. Activities of the extracts for DPPH, nitric oxide and H2O2 differed significantly (p˂0.05) from the standard antioxidant. For ferric reducing antioxidant power, methanolic extract of D.arborescens roots and methanolic extract of C. dependens roots showed the best reducing ability. Methanolic extract of D. arborescens root showed the highest (2352.94 ±164.87mg AA/g extract) total antioxidant capacity. Extracts of the leaves, stem and roots of D. arborescens did not show any mice toxicity or mortality even at 5000 mg/kg body weight but aqueous and methanolic extracts of C. dependens stem recorded death at 2900 mg/kg b.wt and 5000 mg/kg b.wt. Sub-acute oral toxicity test of the extracts revealed significant increase (p ˂0.05) on haematological parameters (PCV, Hb, RBCs, WBCs, MCH, Neutrophils, Lymphocytes and MCHC) at 200 mg/kg-1 body weight. For biochemical parameters (ALT, AST, ALP, total protein, and albumin), extracts did not significantly differ (p˂0.05) from the standard and normal control. All the extracts showed significant (p˂0.05) antimalarial activities compared to the untreated control. These activities however, differed (p˂0.05) from the standard antimalarial drug (artesunate). Methanolic extract of D.arborescens root showed the highest antimalarial activity by reducing percentage parasitemia from 75.2% on day 3 to 16.8% on day 14 after treatment. Column chromatographic separation of this extract gave five fractions at different solvent mixtures. Bioassay revealed that hexane soluble fraction recorded the highest antimalarial activity, and sub-fractionation of this fraction yielded two purer eluates -EA and EB. Phytochemical analysis with Gas chromatography- Flame ionization detector (GC-FID) revealed various phytochemicals with known antimalarial and antioxidant activities. FTIR spectroscopy revealed the presence of functional groups such as alkanes (-CH2-), α-halogeno carboxylic acids (C=O), primary alcohols (C- OH), halides (C-Cl), non conjugated alkenes (C=C), esters (OC – H), aliphatic esters (R-O-R), etc. These functional groups were confirmed by GC-MS analysis which xxi recorded various bioactive compounds such as 1,2 dichloro propane, 1-Octadecene, cis- alpha- bisabolene, Dichloroacetic acid tridecyl ester, 9,17 Octadecadienal, (Z)-, cis-13-Octadecenoic acid, Heptadecanoic acid, 16 methyl-, methyl ester, Bis (2-ethylhexyl) phthalate, Bis(3-methylbutan-2yl) phthalate, Carbonic acid prop-1-ene - 2yl-tetra, 5-Octadecene, (E)-, Hexadecanoic acid methyl ester, 10-Octadecenoic acid methy ester Butyl octadecyl ether methyl tetradecanoate, Heptasiloxane, 1,1,3,3,5,5,7,7,9,9,11,11,13,13 tetradecamethyl. In molecular docking analysis, these bioactive compounds showed various degrees of binding affinities and molecular interactions with two antimalarial protein targets - lactate dehydrogenase (1OC4) and Plasmepsin II (1SME). Binding affinity of Bis(2-ethylhexyl) phthalate and Bis(3-methylbutan-2-yl) phthalate were close to that of the standard antimalarial drug (artesunate) suggesting that these two compounds were responsible for the antimalarial activity exhibited by methanol extract of D.arborescens root. ADMET properties of these two compounds equally suggest no harmful or toxic effects when compared to the standard antimalarial drug (artesunate).
Description
This thesis is for the award of Doctor of Philosophy (PhD.) in Biotechnology
Keywords
Chasmanthera dependens, dictyandra arborescens, phytochemicals, in vitro antioxidants, toxicity antimalarial, isolation, molecular docking, Department of Biotechnology
Citation
Enenebeaku, U. E. (2021). In vitro antioxidant and antimalaria properties of the plants chasmanthera dependens (hochst) and dictyandra arborescens (welw.) [Unpublished Doctoral Thesis]. Federal University of Technology, Owerri, Nigeria