Efere M. Obuotor

Evaluation of Antioxidant and Free Radical Scavenging Capacities of Some Nigerian Indigenous Medicinal Plants

Methanolic extracts of 10 selected Nigerian medicinal plants-Psidium guajava, Alstonia boonei, Cassia alata, Newbouldia laevis, Spondias mombin, Globimetula cupulatum, Chromolaena odorata, Securidaca longepedunculata, Ocimum gratissimum, and Morinda lucida-widely used in ethnomedicine, were assessed for phytochemical constituents and antioxidant and free radical scavenging activities using seven different antioxidant assay methods. Phytochemical screening gave positive tests for steroids, terpenoids, and cardiac glycosides, alkaloids, saponins, tannins, and flavonoids contained in the extracts. P. guajava contained the highest amount of total phenolics (380.08 +/- 4.40 mg/L gallic acid equivalents), and the highest amounts of total flavonoids were found in the leaf extracts of C. alata (275.16 +/- 1.62 microg/mL quercetin equivalents [QE]), C. odorata (272.12 +/- 2.32 microg/mL QE), and P. guajava (269.72 +/- 2.78 microg/mL QE). Percentage 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was highest in S. mombin (88.58 +/- 3.04%) and P. guajava (82.79 +/- 2.84%) and compared with values obtained for ascorbic acid and gallic acid. All the extracts, generally, had low nitric oxide radical scavenging activities, and G. cupulatum had the highest hydroxyl radical scavenging activity (63.84 +/- 0.97%). The extracts in general demonstrated high lipid peroxidation inhibitory activity, with only M. lucida (38.74 +/- 1.99%) and A. boonei (47.16 +/- 0.59%) being exceptions. The reductive potential was highest in P. guajava (0.79 +/- 0.04) and least in S. longepedunculata (0.26 +/- 0.00). DPPH assay correlated well with total phenolic contents (r(2) = 0.76) and reductive potential (r(2) = 0.81) and fairly with lipid peroxidation inhibitory activity (r(2) = 0.51). There was a good correlation between total phenolic contents and reductive potential (r(2) = 0.79) and a fair correlation between total phenolic contents and lipid peroxidation inhibitory activity (r(2) = 0.55). These results suggest that the methanolic extracts of the studied plant parts possess significant antioxidant and radical scavenging activities that may be due to the phytochemical content of the plants and as such make them potential candidates as natural chemoprophylactic agents. In addition, multiple assay methods should be used in comparing antioxidant capacities of samples to have a reliable result.

Doubly linked, A-type proanthocyanidin trimer and other constituents of Ixora coccinea leaves and their antioxidant and antibacterial properties

Phytochemical investigation of the ethyl acetate fraction of the methanol extract of the leaves of Ixora coccinea led to the isolation and identification of an A-type trimeric proanthocyanidin epicatechin-(2β→O→7, 4β→8)-epicatechin-(5→O→2β, 6→4β)-epicatechin named ixoratannin A-2 along with seven known compounds, epicatechin, procyanidin A2, cinnamtannin B-1, and four flavon-3-ol rhamnosides viz: kaempferol-7-O-α-L-rhamnnoside, kaempferol-3-O-α-L-rhamnoside, quercetin-3-O-α-L-rhamnopyranoside, and kaempferol-3,7-O-α-L-dirhamnoside. The structures were elucidated by the application of IR, UV, MS, 1D-, and 2D-NMR spectroscopic analyses and by comparison with literature data. Antioxidant evaluation of isolated compounds revealed that ixoratannin A-2 and cinnamtannin B-1 were the most active compounds in DPPH, inhibition of lipid peroxidation and nitric oxide radical scavenging assays. Antibacterial activities were assessed by means of agar-diffusion assays using Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis. All tested compounds inhibited the growth of B. subtilis, while only epicatechin and quercetin-3-O-α-L-rhamnopyranoside inhibited the growth of E. coli.

Antibacterial activity of Piliostigma thonningii stem bark.

Piliostigma thonningii stem bark 60% methanolic extract exhibited activity against six out of eight bacterial isolates at a concentration of 20 mg/ml.

Acetylcholinesterase and butyrylcholinesterase inhibitory activity of some selected Nigerian medicinal plants

As plantas podem ser uteis para estimular a memoria, bem como serem usadas para combater o envelhecimento. Vinte e duas plantas, de dezesseis familias, foram investigadas in vitro oara verificar sua atividade inibidora das enzimas acetilcolinesterase (AChE) e butirilcolinesterase (BuChE) pelo metodo espectrofotometrico de Ellman in situ e metodos de bioautografia utilizando fisostigmina como padrao. Pelo menos tres partes morfologicas de cada planta foram analisadas e a concentracao de ensaio foi de 42,5 µg/mL. Algumas plantas foram ativas em ambas as enzimas, embora com algumas partes mais ativas que outras. A casca da raiz de Spondias mombin apresentou a maior atividade as duas enzimas, 64,77% para AChE e 83,94% para BuChE. Outras partes das plantas selecionadas apresentaram boa seletividade em suas acoes. As plantas seletivamente ativos contra AChE foram as casca do caule e casca da raiz de Alchornia laxiflora (41,12%), e casca da raiz de Callophyllum inophyllurn (56,52%). As folhas de C. jagus (74,25%), folhas de Morinda lucida (40,15%), folhas e casca do caule de Peltophorum pterocarpum (49,5% e 68,85%, respectivamente), physiostigmine inibiu 90,31%. Em geral, atividades melhoras foram apresentadas contra BuChE. Folhas, casca da raiz e casca do caule Bombax bromoposenze foram particularmente ativos. A inibicao foi acima de 80%. Outras partes de algumas especies tambem foram seletivas, como as partes aereas de Antiaris africana, Cissampelos owarensis (78,96%), folhas e casca do caule de Combretum molle (90,42% e 88,13%, respectivamente), casca da raiz e de tuberculos de Dioscorea dumentorum (mais de 87%), folhas de G cola, cascas de raiz de Markhamia tomentosa, casca do caule de Pycnanthus angolensis e folhas de Tetrapleura tetraptera. A maioria destas plantas sao utilizadas como alimentos ou ingredientes alimentares na Nigeria e podem ser responsaveis pela baixa incidencia da doenca de Alzheimer no pais e desempenhar determinadas funcoes na mediacao da doenca.

Preliminary evaluation of cytotoxic properties of Raphia hookeri fruit mesocarp.

The aqueous and n-butanol fractions of the methanolic extract of Raphia hookeri fruit mesocarp was evaluated for cytotoxic properties using three different bioassays. The n-butanol fraction exhibited greater cytotoxicity than the aqueous fraction when tested against brine shrimp, mosquito larvae, and 5-day old tadpoles, the cytotoxicity towards the tadpoles being the most pronounced (LC(50)=0.83 ppm).

Antibacterial activity of Nicotiana tabacum leaves

Nicotiana tabacum leaf 60% methanolic extract exhibited antibacterial activity against six out of nine bacterial isolates at a concentration of 25 mg/ml.

Anticholinesterase constituents from the leaves of Spondias mombin L. (Anacardiaceae)

Spondias mombin has been used in traditional medicine for the management of several diseases, including memory loss. This study aimed to evaluate the cholinesterase inhibitory activity of the methanol extract of the leaves and its derived fractions, as well as carry out detailed phytochemical investigations leading to the isolation and characterization of bioactive compounds from the plant. The acetyl cholinesterase (AChE) and butyryl cholinesterase (BUChE) inhibitory activities were evaluated by colorimetric and thin-layer chromatography bioautographic assay techniques. The ethyl acetate fraction was most active against both enzymes, with percentage inhibition of 58.10 ± 1.08% and 52.66 ± 1.34% against AChE and BUChE, respectively. Three compounds, namely, botulin, campesterol and phytol, with IC50 of 0.88 μg/mL (AChE), 4.67 μg/mL (BuChE); 1.89 μg/mL (AChE), 4.08 μg/mL (BuChE) and 12.51 μg/mL (AChE), 23.89 μg/mL (BuChE), respectively, were isolated from the supernatant of the ethyl acetate fraction. The isolated cholinesterase inhibitory compounds correlate with the known memory-enhancing property of the plant and thus support one of its uses in ethnomedicine.

ISOLATION AND CHARACTERIZATION OF CHEMICAL CONSTITUENTS FROM CHRYSOPHYLLUM ALBIDUM G. DON-HOLL. STEM-BARK EXTRACTS AND THEIR ANTIOXIDANT AND ANTIBACTERIAL PROPERTIES.

Background: The plant, Chrysophyllum albidum is indigenous to Nigeria and its stem-bark has wide application in traditional medicine for the treatment of infections and oxidative stress related diseases. The aim of the study was to isolate the chemical constituents responsible for the antioxidant and antibacterial activity from the stem-bark of the plant in order to justify some of its ethnomedicinal uses. Materials and Methods: Crude extract of stem-bark of Chrysophyllum albidum obtained from 80% ethanol was successively partitioned with ethyl acetate (EtOAc) and n-butanol. The solvent fractions and isolated compounds were tested for antioxidant property using 2-2-diphenyl-1-picrylhydrazyl. Antibacterial activities were also assessed by means of agar-diffusion and broth micro dilution methods. EtOAc fraction was repeatedly fractionated on column chromatography to afford four compounds and their chemical structures were established using NMR (1D and 2D) and MS. Results: Chromatographic fractionation of EtOAc fraction with the highest antioxidant and antimicrobial activities afforded stigmasterol (1),: epicatechin (2),: epigallocatechin (3): and procyanidin B5 (4).: Procyanidin B5 isolated for the first time from genus Chrysophyllum demonstrated the highest antioxidant activity with IC50 values of 8.8 μM and 11.20 μM in DPPH and nitric oxide assays respectively and equally demonstrated the highest inhibitory activity against Escherichia coli (MIC 156.25 μg/mL), Staphylococcus aureus (MIC 156.25 μg/mL), Pseudomonas aeruginosa (MIC 625 μg/mL) and Bacillus subtilis (MIC 156.25 μg/mL). Conclusion: The antibacterial and antioxidant activities of epicatechin, epigallocatechin and procyanidin B5 isolated from Chrysophyllum albidum stem-bark validate the folkloric uses.

Assessment of the Effects of Graded Doses of Polyphenolic-Rich Fraction of Garcinia kola Seeds on Pituitary–Testicular Axis of Male Wistar Rats

This study evaluated the ameliorative and prophylactic effects of 2 different doses of polyphenolic-rich fraction of Garcinia kola (PPRFGk) seeds on the histology and hormones of pituitary–testicular axis of male Wistar rats. Thirty-five male Wistar rats (150-200 g) were divided into 7 groups of 5 rats each. Groups I and II were given distilled water (0.5 mL/day) for 8 days followed by propylene glycol (0.2 mL/d) and 600 mg/kg of PPRFGk, respectively, for 21 days. Group III received sodium arsenate (8 days), left untreated for 21 days. Groups IV and V received sodium arsenate (20 mg/kg) for 8 days followed by PPRFGk (300 and 600 mg/kg, respectively) for 21 days. Groups VI and VII received PPRFGk (300 and 600 mg/kg, respectively) for 21 days followed by sodium arsenate (20 mg/kg) for 8 days. Rats were killed by cervical dislocation 24 hours after the last dose and their blood collected through cardiac puncture. Blood sera were assayed for the levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone using immunoassay techniques. Histology of the pituitary gland and testes was carried out. A significant reduction was observed in the concentration of FSH in groups IV, V, VI, and VII in comparison with groups I and II. The concentrations of both LH and testosterone showed significant decreases in groups IV, V, VI, and VII in comparison with group I. Group III presented with the lowest serum hormonal concentrations. Photomicrographs of the pituitary gland revealed greatly reduced basophils in group III and mildly reduced basophils in groups IV, VI, and VII in comparison with groups I and II. Group V revealed hypercellularized and distorted basophils. Photomicrographs of the testes showed detachment of the seminiferous tubules from the basement membrane and disruption of the interstitial space which was worse in group III, moderate in groups V and VI, and mild in group VII. In conclusion, PPRFGk effected a dose-dependent reversal and prevention of the perturbations caused by arsenate in rats.

Cerebrospinal fluid and plasma β-endorphin levels in children with cerebral malaria

Cerebral malaria (CM) is the most lethal form of malaria, yet its pathogenesis is not fully understood. Cytoadherence, sequestration, alterations in cytokine expression, inflammation, and microvascular obstruction are all hypothesized to be important in the aetio‐pathogenesis of coma which characterizes cerebral malaria and the death which sometimes result. Beta (β)‐endorphin has been postulated to be involved in the pathogenetic processes of inflammation and cytokine expression, although the exact role is unknown. The aim of this study was to determine the levels of β‐endorphin in cerebrospinal fluid (CSF) and plasma of children with CM and compare the levels of β‐endorphin in the plasma of children with CM with that of apparently healthy age‐ and sex‐matched controls at Ile‐Ife, Nigeria.