Joseph Ngoupayo - Academia.edu (original) (raw)

Papers by Joseph Ngoupayo

Zeitschrift fuer Naturforschung B, 2017

Reactive oxygen species are the cause of different ailments such as cancer. The intake of foods r... more Reactive oxygen species are the cause of different ailments such as cancer. The intake of foods rich in antioxidant compounds may prevent the occurrence of these diseases. Thus, antioxidants play important role in controlling the free radical disorders. In the present work, the antioxidant potential of 48 different extracts, fractions and pure compounds of five medicinally important plants was evaluated by using the DPPH method. Methyl gallate obtained from the Acalypha torta showed good antioxidant activity (EC50 = 2.3 g/ml). Vanillic acid isolated from Clerodendrum formicarum showed moderate antioxidant activity (EC50 = 50 g/ml). Acalypha segetalis and Erythrina were found inactive during the study (EC50 >200 g/ml). The above plants could provide rich supply of natural antioxidants and may possible preventive agents in ROS related ailments.

Natural Product Communications, Nov 1, 2007

Brevipsidone (1), a new depsidone was isolated from the methanol extract of the stem bark of Garc... more Brevipsidone (1), a new depsidone was isolated from the methanol extract of the stem bark of Garcinia brevipedicellata together with known damnacanthal (2), pilloin (3), scopoletin (4). The structure of the new compound was determined by analysis of spectroscopic data. Compounds 1-4 were evaluated for their α-glucosidase inhibition effect and showed significant inhibitory activity.

Journal of Asian Natural Products Research, Oct 1, 2010

The ethanolic extract of the leaves of Clerodendrum formicarum, a Lameacious plant of Cameroon, a... more The ethanolic extract of the leaves of Clerodendrum formicarum, a Lameacious plant of Cameroon, afforded two new salicylic acid derivatives named formoic acids A and B along with four known constituents which have been obtained for the first time from this source. They include flemingipanic acid, martynoside, verbascoside, and seguinoside K. Structures of all the isolated constituents have been elucidated with the aid of 1D and 2D NMR spectroscopic techniques.

Magnetic Resonance in Chemistry, May 27, 2015

Natural Product Research, Apr 17, 2023

Journal of Pharmacognosy and Phytochemistry, 2020

Traditional African Medicine in general and Cameroonian in particular use medicinal plant recipes... more Traditional African Medicine in general and Cameroonian in particular use medicinal plant recipes to treat various pathologies. In order to improve the safety and the progressive integration of those plants in our health systems, it is important to set protocol that would permit an easy characterization of medicinal plants. This study is interested in a recipe of Bridelia micrantha and Persea americana trunk’s bark, traditionally used in the center region of Cameroon to treat “hemorrhoids”. Thus, we develop the macrography, the micrography, the phytochemical screening, the water content and the total ash content percentages of the stem bark of each plant. The water contents in P. americana and B. micrantha are 7.82±1% and 10.16±% respectively. And total ash content are 3.36±1% and 4.25±1% for P. americana and B. micrantha respectively. Micrography of truncated P. americana bark showed: cells containing crystals of calcium oxalate and spindle sclerified fibers. That from B. micrantha...

Chemistry of Natural Compounds, 2018

A new phenolic ester, viridone (1), has been isolated from the EtOH soluble part of Ocimum viride... more A new phenolic ester, viridone (1), has been isolated from the EtOH soluble part of Ocimum viride, along with previously reported known compounds: ursolic acid (2), oleanolic acid (3), stigmasterol (4), E-sitosterol-glucoside (5), 7-hydroxycoumarin (6), jacarandic acid (7), pedunculin (8), and crismaritin (9). Their structures were elucidated by spectroscopic techniques including two-dimensional NMR. Viridone (1) showed significant inhibitory activity against butyrylcholinesterase.

Journal of Asian Natural Products Research, 2010

The present investigation addressed a semi-quantitative chemical screening of a few known bioacti... more The present investigation addressed a semi-quantitative chemical screening of a few known bioactive secondary metabolites and the antimicrobial potentials of crude extracts from the flowers and stem of Hyphaene thebaica (H. thebaica). Those chemicals targeted included: alkaloids, coumarins, flavonoids, anthocyanins, mucilages, glycosides, polyphenols, quinones, saponosids and terpenoids. The solvents used were methanol and ethyl acetate. The antimicrobial activity was tested according to standard protocols on nine bacterial strains from both Gram types and C. albicans. This was done through determination of the minimal inhibitory and minimal lethal concentrations; and the diameters of growth inhibition. Almost all chemicals targeted were present in both crude extracts but extraction with methanol was more effective than extraction with ethyl acetate. At varying levels regardless of the Gram type and the origin of the extracts, the antimicrobial activity extended to all tested organi...

Journal of Tropical Pharmacy and Chemistry

The increase incidence of fungal infections, the resistance of fungal strains to existing drugs a... more The increase incidence of fungal infections, the resistance of fungal strains to existing drugs and the toxicity assimilated to long term usage of antifungal drugs as prompted the search of new alternative from natural source. In this study we have evaluated the antifungal properties of the essential oil of the rhizome of Z. officinale, a plant known for its various biological properties and used in food industry as spice. An antifungal ointment with Z. officinale essential oil as active principle was also formulated and its antifungal properties evaluated. GC/MS analysis identified Zingiberene (22.36%), 1.8-cineole (15.54%), geranial (11.91%), camphene (11.09%) and geraniol (8.75%) as the main constituents of Z. officinale essential oil obtained by hydrodistillation. The oil showed a significant antifungal activity against clinical isolate of Candida krusei with MIC 800 ppm by microdilution method. The formulated ointment containing 10 % glycerol, 60 % vaseline, 8 % hydrosol, 20% l...

Journal of Pharmacognosy and Phytotherapy, 2018

The present investigation focused on a semi-quantitative chemical screening of a few known second... more The present investigation focused on a semi-quantitative chemical screening of a few known secondary metabolites and the antimicrobial potentials of two extracts from the bark of Oldfieldia africana (O. africana). The targeted compounds included: alkaloids, coumarins, flavonoids, glycosides, phytosterols, quinones, saponins, terpenoids, mucilages, total phenols and tannins. Extraction was conducted with two organic solvents: methanol and ethyl acetate. The antimicrobial activity was tested on nine bacterial strains from both Gram types and C. albicans with the methanolic crude extract. This was done through determination of the minimal inhibitory and minimal lethal concentrations (MICs, MLCs, respectively) and the diameters of growth inhibition. All chemicals targeted were present in the plant, but not in all extracts. Extraction with methanol proved more effective than using ethyl acetate. At varying levels, the antimicrobial activity extended to all tested organisms (MIC values: 1...

GSC Biological and Pharmaceutical Sciences, 2021

The high incidence of infectious diseases and the emergence of resistance to modern drugs are cur... more The high incidence of infectious diseases and the emergence of resistance to modern drugs are current public health concerns. This situation leads to the search for alternatives via medicinal plants. The objective of this study was to assess the properties of Vernonia conferta. We performed an experimental study. The plant material consisted of the leaves and trunk bark of V. conferta. The extraction was carried out by maceration using aqueous and hydro-ethanolic solvents, followed by phytochemical screening of the extracts. An evaluation of the antibacterial potential was carried out by the micro-dilution method and was followed by the evaluation of the antioxidant properties (DPPH and FRAP test) and cytotoxicity (resazurin staining) of the extracts. The E2 and E4 extracts exhibited better extraction yields. The phytochemical screening noted the presence of families of compounds in common (polyphenols, tannins and quinones) and those which are different. The hydro-ethanolic extract...