Constant Anatole Pieme

In vitro antibacterial activity and acute toxicity studies of aqueous-methanol extract of Sida rhombifolia Linn. (Malvaceae)

AbstractBackgroundMany bacteria among the Enterobacteria family are involved in infectious diseases and diarrhoea. Most of these bacteria become resistant to the most commonly used synthetic drugs in Cameroon. Natural substances seem to be an alternative to this problem. Thus the aim of this research was to investigate the in vitro antibacterial activity of the methanol and aqueous-methanol extracts of Sida rhombifolia Linn (Malvaceae) against seven pathogenic bacteria involved in diarrhoea. Acute toxicity of the most active extract was determined and major bioactive components were screened.MethodsThe agar disc diffusion and the agar dilution method were used for the determination of inhibition diameters and the Minimum Inhibitory Concentration (MICs) respectively. The acute toxicity study was performed according WHO protocol.ResultsThe aqueous-methanol extract (1v:4v) was the most active with diameters of inhibition zones ranging from 8.7 - 23.6 mm, however at 200 μg/dic this activity was relatively weak compared to gentamycin. The MICs of the aqueous-methanol extract (1v:4v) varied from 49.40 to 78.30 μg/ml. Salmonella dysenteriae was the most sensitive (49.40 μg/ml). For the acute toxicity study, no deaths of rats were recorded. However, significant increase of some biochemical parameters such as aspartate amino-transferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and creatinine (CRT) were found. The phytochemical analysis of the aqueous methanol extract indicated the presence of tannins, polyphenols, alkaloids, glycosides, flavonoids and saponinsConclusionThe results showed that the aqueous-methanol extract of S. rhombifolia exhibited moderate antibacterial activity. Some toxic effects were found when rats received more than 8 g/kg bw of extract. Antibacterial; Enterobacteria; Acute toxicity; Phytochemical analysis

In vitro cytotoxicity and antioxidant activities of five medicinal plants of Malvaceae family from Cameroon

The potential antiproliferative and antioxidant activities of extracts from five medicinal plants from Cameroon were evaluated in vitro on HepG-2 cells. The results showed the significant decrease of the viability of the cells in a concentration-dependent manner. According to the IC(50) obtained, the extracts of S. acuta (461.53±0.23) and U. lobata (454.93±0.12) showed significant antiproliferative activity. At fixed concentration (250μgmL(-1)), extracts demonstrated higher antiproliferative activity (67.05%; 65.42%), (52.62%; 56.64%) and (32.98%; 36.85%) respectively during 24, 48 and 72h. Extracts of S. cordifolia and V. album demonstrated significant antiproliferative property after 48h while S. rhombifolia exhibited weak cytotoxicity. The results of the antioxidant properties showed that theses extracts induced significantly increase of SOD, CAT and GsT activity after 48h. Taken together, the results extracts showed that of S. acuta and U. lobata may be a promising alternative to synthetic substances as natural compound with high antiproliferative and antioxidant activities.

Syzyguim guineense Extracts Show Antioxidant Activities and Beneficial Activities on Oxidative Stress Induced by Ferric Chloride in the Liver Homogenate

The aim of this study was to determine the in vitro antioxidant activity, free radical scavenging property and the beneficial effects of extracts of various parts of Syzygium guineense in reducing oxidative stress damage in the liver. The effects of extracts on free radicals were determined on radicals DPPH, ABTS, NO and OH followed by the antioxidant properties using Ferric Reducing Antioxidant Power assay (FRAP) and hosphomolybdenum (PPMB). The phytochemical screening of these extracts was performed by determination of the phenolic content. The oxidative damage inhibition in the liver was determined by measuring malondialdehyde (MDA) as well as the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and peroxidase. Overall, the bark extract of the ethanol/water or methanol showed the highest radical scavenging activities against DPPH, ABTS and OH radicals compared to the other extracts. This extract also contained the highest phenolic content implying the potential contribution of phenolic compounds towards the antioxidant activities. However, the methanol extract of the root demonstrated the highest protective effects of SOD and CAT against ferric chloride while the hydro-ethanol extract of the leaves exhibited the highest inhibitory effects on lipid peroxidation. These findings suggest that antioxidant properties of S. guineense extracts could be attributed to phenolic compounds revealed by phytochemical studies. Thus, the present results indicate clearly that the extracts of S. guineense possess antioxidant properties and could serve as free radical inhibitors or scavengers, acting possibly as primary antioxidants. The antioxidant properties of the bark extract may thus sustain its various biological activities.

Fruits and barks extracts of Zanthozyllum heitzii a spice from Cameroon induce mitochondrial dependent apoptosis and Go/G1 phase arrest in human leukemia HL-60 cells

BackgroundZanthoxylum heitzii is a spice used to prepare several dishes and to treat tumors, syphilis, malaria, cardiac palpitations, urogenital infections in the west region of Cameroon, but the antitumor mechanisms and chemical composition are not yet investigated.This study was aimed to determine the antiproliferative effects of four extracts from the fruits and barks of Zanthoxyllum heitzii (Rutaceae) on apoptosis in human promyelocytic cells, their mechanisms and the chemical composition. The 3-(4, 5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the fifty percent inhibition (IC50) concentration of the cell lines after treatment. The effect on morphology was observed using a light or fluorescence microscopy. The rate of apoptosis and the cell cycle were measured using flow cytometry (FCM). The phytochemical analysis of the extract was carried with HPLC/MS methods.ResultsThe phytochemical analysis of the extracts indicated the presence of four known polyphenols (Syringic acid, Juglon, Luteolin and Myricetin) in both fruits and barks of Z. heitzii but in different quantities. Syringic acid and Myricetin concentrations were between 17-21 fold higher in the fruits than the stem bark. Rhamnetin (393.35 μg/mL) and Oleuropein (63.10 μg/mL) were identified only in the stem barks of Z. heitzii. Among the four extracts tested for cytotoxicity properties, only the methanol extract of fruits and barks significantly inhibited cell proliferation of HL-60 cells with IC50 value of 20 μg/mL and 12 μg/mL respectively. HL-60 cells treated with Z. heitzii extracts significantly produced reactive oxygen species (ROS) with concurrent loss of mitochondrial membrane potential (MMP). Modifications in the DNA distribution and enhanced of G1/G0 phase cell cycle arrest were observed in a concentration dependent manner.ConclusionsPolyphenols from Z. heitzii plant exert inhibitory effect on HL-60 cells through the reactive oxygen species (ROS) generation, loss of mitochondrial membrane potential and cell cycle destabilization.

Phenolic Content of Hypodaphnis Zenkeri and Its Antioxidant Effects against Fenton Reactions’ Mediated Oxidative Injuries on Liver Homogenate

Under oxidative stress conditions, endogenous antioxidant defenses are unable to completely inactivate the free radicals generated by an excessive production of reactive oxygen species (ROS). This state causes serious cell damage leading to a variety of human diseases. Natural antioxidants can protect cells against oxidative stress. Hypaodaphnis zenkeri (H. zenkiri) is a plant consumed as a spice in the Cameroonian diet, and its bark has been used in traditional medicine for the treatment of several diseases. The present study aims at investigating the antioxidant activity, which includes free radical scavenging and protective properties of an extract from H. Zenkiri against oxidative damage on a liver homogenate. The free radical assays determined the scavenging activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl (OH), nitrite oxide (NO) and 2,2-azinobis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radicals and the enzymes, whose protection was to be considered in the liver homogenate, including superoxide dismutase, catalase, and peroxidase. The antioxidative activities were studied using the ferric reducing antioxidant power (FRAP), reductive activity, and phosphomolybdenum antioxidant power (PAP) methods. In addition, the phenolic contents of the extracts were examined. The results showed that these extracts demonstrated significant scavenging properties and antioxidant activities, with the hydro-ethanolic extract of the bark of H. zenkeri (EEH) being the most potent. This extract had the highest total polyphenol (21.77 ± 0.05 mg caffeic acid (CAE)/g dried extract (DE)) and flavonoids (3.34 ± 0.13 mg quercetin (QE)/g dried extract) content. The same extract had significantly greater protective effects on enzyme activities compared to other extracts. The high performance liquied chromatography (HPLC) profile showed higher levels of caffeic acid, OH-tyrosol acid, and rutin in the leaves compared to the bark of H. zenkeri. In conclusion, the ethanolic and hydro-ethanolic extracts of the bark and leaves from H. zenkeri showed an antioxidant and protective potential against oxidative damage.

In vitro antiproliferative and anti-oxidant activities of methanol extracts of Urena lobata and Viscum album against breast cancer cell lines

The therapeutic utilization of plants is a part of universal human culture. Presently, phytotherapy is considered as an alternative to mitigate side effects due to the indiscriminate use of synthetic drugs. The aim of this study was to investigate the in vitro antiproliferative and antioxidant activities of Viscum album and Urena lobata extracts on breast cancer cell lines. The results of the antiproliferative activity demonstrated the significant reduction of the cells viability with the IC50 of 181 and 172 mg L−1, respectively for U. lobata and V. album extract. At the concentration of 100 and 200 mg L−1, the two extracts exhibited a linear and significant reduction of cells viability after 24, 48, and 72 h. The significant variation of superoxide dismutase, catalase, and glutathione-S-transferase activities was found with both extracts at 100 mg L−1 after 24, 48, and 72 h. Urena lobata and V. album extracts demonstrated significant antiproliferative and antioxidant properties on MB-MDA435 cell lines.

Antioxidant and Synergistic Antidiabetic Activities of a Three-Plant Preparation Used in Cameroon Folk Medicine

Introduction. Several plant preparations like a mixture of aqueous extracts of Spilanthes africana; Portulaca oleracea; and Sida rhombifolia are currently utilized in Foumban (West Cameroon) to manage diabetes. The aim of this study is to investigate the antidiabetic property of the aqueous mixture of three plant extracts (1 : 1 : 1) on streptozotocin induced diabetes rats. Methods. Diabetes was induced to rats by intraperitoneal (i.p.) injection of streptozotocin (STZ) at a dose of 50 mg/kg b.w. The diabetic rats received different dosages of the mixture of extracts for 21 days and glibenclamide 6.5 mg/kg b.w. as positive control. Results. The results showed that the mixture of extracts significantly (p < 0.05) decreased the level of the glycaemia, the total cholesterol, triglyceride, and LDL-cholesterol as well as MDA, AST, ALT, and creatinine levels. It also increased significantly the concentration of HDL-cholesterol, glutathione, and TAOS. A great reduction of the atherogenic indexes CT/HDL and LDL/HDL of the treated groups was observed. Each extract and the mixture demonstrated significant scavenging property on DPPH and OH radicals and present a good antioxidant property. Conclusion. The mixture of plant extracts has hypoglycemic, antioxidant, and hypolipidemic properties and can be used for the management of diabetes mellitus.

HIV-Infected or -Exposed Children Exhibit Lower Immunogenicity to Hepatitis B Vaccine in Yaoundé, Cameroon: An Appeal for Revised Policies in Tropical Settings?

Background Since 2005, anti-hepatitis B virus (anti-HBV) vaccine is part of the Expanded Program on Immunization (EPI) for infants born in Cameroon, with 99% anti-HBV coverage. In a context of generalized HIV epidemiology, we assessed paediatric anti-HBV vaccine response according to HIV status, feeding option and age in a tropical context. Methodology Prospective, observational and cross-sectional study conducted among 82 children (27 [IQR: 9–47] months, min-max: 6–59), after complete anti-HBV vaccination (Zilbrix Hepta: 10μg AgHBs) at the Essos Health Centre in Yaounde, Cameroon, classified as group-A: HIV unexposed (28), group-B: HIV-exposed/uninfected (29), group-C: HIV-infected (25). Quantitative anti-HBs ELISA was interpreted as “no”, “low-” or “protective-response” with <1, 1–10, or ≥10 IU/L respectively; with p-value<0.05 considered significant. Results Children were all HBV-unexposed (AcHBc-negative) and uninfected (HBsAg-negative). Response to anti-HBV vaccine was 80.49% (66/82), with only 45.12% (37/82) developed a protective-response (≥10IU/L). According to HIV status, 60.71% (17/28) developed a protective-response in group-A, vs. 51.72% (15/29) and 20% (5/25) in group-B and group-C respectively, Odds Ratio (OR): 2.627 [CI95% 0.933–7.500], p = 0.041. According to feeding option during first six months of life, 47.67% (21/45) developed a protective-response on exclusive breastfeeding vs. 43.24% (16/37) on mixed or formula feeding, OR: 1.148 [CI95% 0.437–3.026], p = 0.757. According to age, protective-response decreased significantly as children grow older: 58.33% (28/48) <24 months vs. 26.47% (9/34) ≥24 months, OR: 3.889 [CI95% 1.362–11.356], p = 0.004; and specifically 67.65% (23/34) ≤6 months vs. 0%, (0/5) 33–41 months, p = 0.008. Conclusions Anti-HBV vaccine provides low rate of protection (<50%) among children in general, and particularly if HIV-exposed, infected and/or older children. Implementing policies for early vaccination, specific immunization algorithm for HIV-exposed/infected children, and monitoring vaccine response would ensure effective protection in tropical settings, pending extensive/confirmatory investigations.

In vitro antioxidant and anti-lipoperoxidative activities of bark extracts of Xylopia aethiopica against ion-mediated toxicity on liver homogenates.

Abstract Reactive oxygen species (ROS), products of normal cell metabolism may cause damage to biological macromolecules leading to severe health threats when they are present in high concentrations. Aromatic plants contain phytochemicals rich of antioxidants that prevent oxidant formation or scavenge oxidants produced under oxidative stress conditions. In the present study, we investigated the free radical scavenging effects, the antioxidant and ion toxicity preventive effect of Xylopia aethiopica (X. aethiopica), a plant of the family of Annonaceae used as spice in Cameroon. The scavenging properties of extracts of X. aethiopica were tested on 2, 2-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO), hydroxyl (OH), 2,2′-azinobis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radicals. The total antioxidant capacity was assayed by ferric reducing ability of plasma (FRAP), phosphomolybdenum antioxidant power (PAP), reduction assays. The protective potential was carried on superoxide dismutase (SOD), catalase and peroxidases. The results showed that both the ethanolic (BEE) and the hydroethanolic (BEH) extracts from the barks of X. aethiopica scavenged all the tested radicals. The sample BEH showed the highest total antioxidant capacity both in the FRAP and the PAP. This result was positively correlated to its higher phenolic content (30.74±0.44 CAE/g dried extract). The higher protective capacity of BEH on SOD, catalase and peroxidase activities was comparable to that of the vitamin C used as standard. In conclusion, X. aethiopica has a higher antioxidant and protective potential against ion-mediated oxidative damage and may be considered as a potential drug against metal-mediated toxicity.

Organo-protective and antioxidant properties of leaf extracts of Syzygium guineense var macrocarpum against ferric nitriloacetate-induced stress of Wistar rats

Abstract Background The present study focused on the antioxidant, phenolic profile and free radical scavenging-mediated protective effect of leaves extracts of Syzygium guineense var. macrocarpum against ferric nitriloacetate-induced stress in the liver, heart, kidney and brain tissues of Wistar rats homogenates. Methods Spectrophotometric standardized methods were used to determine the free radical scavenging potential, antioxidant and protective properties of plant extracts on rat homogenates. Results All the extracts showed a concentration-dependent free radical quenching potential, and the ability to protect all the tested organs by inhibiting the lipid peroxidation and potentiating or restoring the activity of enzymatic and non enzymatic markers. The polyphenolic profile revealed the presence of at least one simple phenolic acid (gallic, caffeic, para-coumaric acid) although the majority (6 out of 14) of the compounds used as standard are present in the aqueous and aqueous–ethanol extracts. Conclusions Ethanolic extract of leaves of S. guineense var macrocarpum (SGETOH) exhibited the highest phenol content and appeared as the best extract taking into consideration the antioxidant and organo-protective activities tested.