A New Ceramide from Cissus Aralioides Baker (Vitaceae) and its Antimicrobial Activity.

Purification through repeated column chromatography over silica gel and Sephadex LH-20 of the ethanol extract of the stems of Cissus aralioides (Baker) Planch. resulted in the isolation of a new ceramide, aralioidamide A (1), along with five known compounds (2-6). Their structures were determined by the extensive analyses of their spectroscopic (1D and 2D NMR) and spectrometric data, and comparison with those reported in the literature. Aralioidamide A (1) displayed weak antibacterial activity (MIC=256 µg/mL) against Bacillus subtilis, Staphylococcus aureus and Shigella flexneri and was inactive (MIC>256 µg/mL) against the tested fungi.

Multidrug-Resistant Escherichia coli Causing Urinary Tract Infections among Controlled and Uncontrolled Type 2 Diabetic Patients at Laquintinie Hospital in Douala, Cameroon.

Urinary tract infections (UTIs) in patients with diabetes are a major public health problem worldwide, particularly in developing countries. This study assessed the resistance profile of Escherichia coli and biochemical abnormalities in controlled and uncontrolled type 2 diabetic patients. A cross-sectional study was conducted at the Douala Laquintinie Hospital from January, 2020, to July, 2021, on the diabetic and nondiabetic participants. The clinical symptoms and biochemical parameters of patient having UTIs were measured using standard methods. E. coli was isolated from urine and an antibiotic susceptibility test was performed using the Kirby-Bauer Agar diffusion method. A total of 851 participants were included with a mean age of 48.54 years. Three hundred and forty-six (40.67%) were nondiabetic, 226 (26.56%) were diabetic patients with balanced blood sugar levels (i.e., glycosylated haemoglobin (HbA1c) is normal), and 279 (32.78%) were diabetic patients with unbalanced blood sugar levels (i.e., patients having an abnormal HbA1c). The prevalence of UTI caused by E. coli was significantly (p < 0.001) higher in diabetics with unbalanced blood sugar levels (15.41%) and diabetics with balanced blood sugar levels (9.73%) compared to nondiabetics (0.87%). Significant (p < 0.001) high frequencies of polyuria (48.39%), proteinuria (29.75%), leukocyturia (27.96%), and polyphagia (8.24%) were observed in diabetic participants with unbalanced blood sugar levels. Significantly (p < 0.001) high average values of aspartate transaminase (25.34; 27.07; 29.93), alanine transaminase (26.08; 27.38; 28.20), creatininemia (8.15; 9.67; 11.31), total cholesterol (1.57; 1.83; 2.63), and atherogenic index (3.81; 6.56; 11.73) were noted in nondiabetics, balanced, and unbalanced blood glucose diabetics, respectively. E. coli showed a high level of resistance to ciprofloxacin (30%), amoxicillin (10.8%), and ofloxacin (9.3%) in diabetic participants with unbalanced blood sugar levels. The antibiotic resistance patterns of the E. coli to triple, quadruple, and quintuple antibiotics were higher when participants had diabetes and even more when diabetes was not controlled. The present findings underline an increased susceptibility of diabetic patients with unbalanced blood sugar levels to multidrug resistant E. coli. Further studies should be conducted to determine the causal association between uncontrolled diabetes and bacterial multidrug resistance.

Antimicrobial activities of flavonoid glycosides from Graptophyllum grandulosum and their mechanism of antibacterial action.

BACKGROUND: The search for new antimicrobials should take into account drug resistance phenomenon. Medicinal plants are known as sources of potent antimicrobial compounds including flavonoids. The objective of this investigation was to evaluate the antimicrobial activities of flavonoid glycosides from Graptophyllum grandulosum, as well as to determine their mechanism of antibacterial action using lysis, leakage and osmotic stress assays. METHODS: The plant extracts were prepared by maceration in organic solvents. Column chromatography of the n-butanol extract followed by purification of different fractions led to the isolation of five flavonoid glycosides. The antimicrobial activities of extracts/compounds were evaluated using the broth microdilution method. The bacteriolytic activity was evaluated using the time-kill kinetic method. The effect of extracts on the red blood cells and bacterial cell membrane was determined by spectrophotometric methods. RESULTS: Chrysoeriol-7-O-ß-D-xyloside (1), luteolin-7-O-ß-D-apiofuranosyl-(1 → 2)-ß-D-xylopyranoside (2), chrysoeriol-7-O-ß-D-apiofuranosyl-(1 → 2)-ß-D-xylopyranoside (3), chrysoeriol-7-O-α-L-rhamnopyranosyl-(1 → 6)-ß-D-(4"-hydrogeno sulfate) glucopyranoside (4) and isorhamnetin-3-O-α-L-rhamnopyranosyl-(1 → 6)-ß-D-glucopyranoside (5) were isolated from G. grandulosum and showed different degrees of antimicrobial activities. Their antibacterial activities against multi-drug-resistant Vibrio cholerae strains were in some cases equal to, or higher than those of ciprofloxacin used as reference antibiotic. The antibacterial activities of flavonoid glycosides and chloramphenicol increased under osmotic stress (5% NaCl) whereas that of vancomycin decreased under this condition. V. cholerae suspension treated with flavonoid glycosides, showed a significant increase in the optical density at 260 nm, suggesting that nucleic acids were lost through a damaged cytoplasmic membrane. A decrease in the optical density of V. cholerae NB2 suspension treated with the isolated compounds was observed, indicating the lysis of bacterial cells. The tested samples were non-toxic to normal cells highlighting their good selectivity index. CONCLUSIONS: The results of the present study indicate that the purified flavonoids from G. glandulosum possess antimicrobial activities. Their mode of antibacterial activity is due to cell lysis and disruption of the cytoplasmic membrane upon membrane permeability.

Antimicrobial and antioxidant activities of triterpenoid and phenolic derivatives from two Cameroonian Melastomataceae plants: Dissotis senegambiensis and Amphiblemma monticola.

BACKGROUND: Antimicrobial resistance is a serious threat against humankind and the search for new therapeutics is needed. This study aims to investigate the antimicrobial and antioxidant activities of ethanol extracts and compounds isolated from Dissotis senegambiensis and Amphiblemma monticola, two Cameroonian Melastomataceae species traditionally used for the treatment of fever, malaria and infectious diseases. METHODS: The plant extracts were prepared by maceration in ethanol. Standard chromatographic and spectroscopic methods were used to isolate and identify fourteen compounds from the two plant species [1-6 (from D. senegambiensis), 3, 4 and 7-14 (from A. monticola)]. A two-fold serial micro-dilution method was used to determine the minimum inhibitory concentration (MIC) against four bacterial strains including two resistant bacterial strains, methicillin resistant S. aureus (MRSA3) and methicillin resistant S. aureus (MRSA4) and three yeast strains. RESULTS: The fractionation of EtOH extracts afforded fourteen compounds belonging to triterpenoid and phenolic derivatives. The ethanol extracts, compounds 3, 5-8, 10 and the mixture of 10 + 12 were active against all the tested bacterial and fungal species. Compound 7 (MIC = 16-32 µg/mL) and 10 (MIC = 8-16 µg/mL) displayed the largest antibacterial and antifungal activities, respectively. Compounds 7, 10 and the mixture of 10 + 12 showed prominent antibacterial activity against methicillin- resistant S. aureus (MRSA) which is in some cases equal to that of ciprofloxacin used as reference antibacterial drug. Compound 8 also showed high radical-scavenging activities and ferric reducing power when compared with vitamin C and butylated hydroxytoluene used as reference antioxidants. The tested samples were non-toxic to normal cells highlighting their good selectivity. CONCLUSIONS: The result of this investigation reveals the potential of D. senegambiensis and A. monticola as well as the most active compounds in the search for new antimicrobial and antioxidant agents. So, further investigations are needed.

Antibacterial secotirucallane triterpenes from the stem bark of Pseudocedrela kotschyi.

The antibacterial-guided investigation of the stem bark extract of Pseudocedrela kotschyi led to the isolation of a new secotirucallane triterpene derivative: 4-hydroxy-3,4-secotirucalla-7,24-dien-3,21-dioic acid (1), together with the known one: 3,4-secotirucalla-4(28),7,24-trien-3,21-dioic acid (2) and 3-methyl ester 3,4-secotirucalla-4(28),7,24-trien-3,21-dioic (3). The structures of the isolated compounds were elucidated on the basis of extensive 1D- and 2D-NMR spectroscopy. Extracts, fractions and compounds (1-3) were tested in vitro for antibacterial activity against two Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus ATCC 25923), and two Gram negative bacteria (Escherichia coli S2(1) and Pseudomonas aeruginosa). The MeOH extract and the Hex/CH2Cl2 (70:30) fraction showed significant levels of activity (MIC=64- 256 µg/mL) compared with the two reference drugs [ciprofloxacin: MIC (0.5-1 µg/mL) and amoxicillin: MIC (1-128 µg/mL)]. Moreover, the compound 2 isolated from this Hex/CH2Cl2 (70:30) fraction had the greatest potential value against S. aureus, E. coli and P. aeruginosa, with minimum inhibitory concentrations (MIC) ranging from 4-16 µg/mL.

Iridoids from Canthium subcordatum iso-butanol fraction with potent biological activities.

BACKGROUND: The continuous emergence of multi-drug-resistant bacteria drastically reduces the efficacy of antibiotic armory and, consequently, increases the frequency of therapeutic failure. The discovery of new antibacterial drugs is an urgent need. The present study reports the antibacterial and antioxidant activities of the methanol extract, fractions and iridoids from Canthium subcordatum, a plant traditionally used as antidiabetic, anti-inflammatory, and antimicrobial. METHODS: Broth microdilution assay was used to determine minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of extracts and iridoids against Staphylococcus aureus, Vibrio cholerae and Shigella flexneri. Antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and gallic acid equivalent antioxidant capacity (GAEAC) assays. The samples were also tested for their cytotoxicity against human red blood cells (RBC). RESULTS: The methanol extract, hexane, ethyl acetate and iso-butanol fractions from C. subcordatum fruits displayed different degrees of antioxidant (EC50 = 62.83-70.17 µg/ml; GAEAC = 45.63-58.23 µg/ml) and antibacterial (MIC = 128-512 µg/ml) activities. Canthiumoside 1(1) and linearin (7) were the most active antioxidant (EC50 = 1.12-2.03 µg/ml; GAEAC = 79.82-92.35 µg/ml) and antibacterial (MIC = 8-64 µg/ml) compounds while the most sensitive bacterium was Staphylococcus aureus. The tested samples were non-toxic to normal cells. CONCLUSION: Our results demonstrated that compounds 1 and 7 were potent antibacterial agents and DPPH/ABTS·+ radical scavengers, so they warrant further investigation.

Antibacterial and cytotoxic cytochalasins from the endophytic fungus Phomopsis sp. harbored in Garcinia kola (Heckel) nut.

BACKGROUND: The continuous emergence of multidrug-resistant (MDR) bacteria drastically reduced the efficacy of our antibiotic armory and consequently, increased the frequency of therapeutic failure. The search for bioactive constituents from endophytic fungi against MDR bacteria became a necessity for alternative and promising strategies, and for the development of novel therapeutic solutions. We report here the isolation and structure elucidation of antibacterial and cytotoxic compounds from Phomopsis sp., an endophytic fungus associated with Garcinia kola nuts. METHODS: The fungus Phomopsis sp. was isolated from the nut of Garcinia kola. The crude extract was prepared from mycelium of Phomopsis sp. by maceration in ethyl acetate and sequentially fractionated by column chromatography. The structures of isolated compounds were elucidated on the basis of spectral studies and comparison with published data. The isolated compounds were evaluated for their antibacterial and anticancer properties by broth microdilution and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide methods respectively. The samples were also tested spectrophotometrically for their hemolytic properties against human red blood cells. RESULTS: The fractionation of the crude extract afforded three known cytochalasins including 18-metoxycytochalasin J (1), cytochalasins H (2) and J (3) together with alternariol (4). The cytochalasin compounds showed different degrees of antibacterial activities against the tested bacterial pathogens. Shigella flexneri was the most sensitive microorganism while Vibrio cholerae SG24 and Vibrio cholerae PC2 were the most resistant. Ampicillin did not show any antibacterial activity against Vibrio cholerae NB2, Vibrio cholerae PC2 and Shigella flexneri at concentrations up to 512 µg/mL, but interestingly, these multi-drug resistant bacterial strains were sensitive to the cytochalasin metabolites. These compounds also showed significant cytotoxic properties against human cancer cells (LC50 = 3.66-35.69 µg/mL) with low toxicity to normal non-cancer cells. CONCLUSION: The three cytochalasin compounds isolated from the Phomopsis sp. crude extract could be a clinically useful alternative for the treatment of cervical cancer and severe infections caused by MDR Shigella and Vibrio cholerae.

Antimicrobial and antioxidant flavonoids from the leaves of Oncoba spinosa Forssk. (Salicaceae).

BACKGROUND: Naturally occurring flavonoids have been reported to possess various pharmacological properties. The aim of this study was to evaluate the antimicrobial and antioxidant activities of the MeOH extract and flavonoids from the leaves of Oncoba spinosa, a plant used for the treatment of syphilis, wounds and sexual impotence. METHODS: The plant extract was prepared by maceration in methanol and sequentially fractionated by column chromatography. The structures of isolated compounds were elucidated on the basis of spectral studies and comparison with published data. The MeOH extract and its isolated compounds were evaluated for their antibacterial and antifungal activities by broth microdilution method. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays were used to detect the antioxidant activity. The samples were tested spectrophotometrically for their hemolytic properties against human red blood cells. RESULTS: The fractionation of the MeOH extract afforded five known flavonoids including kaempferol (1), quercetin (2), apigenin-7-O-ß-D-glucuronopyranoside (3), quercetin 3-O-ß-D-galactopyranoside (4) and quercetin 3-O-α-L-rhamnopyranosyl (1 → 6) ß-D-glucopyranoside (5). The MeOH extract displayed weak to moderate antimicrobial activities (MIC = 256-2048 µg/ml). Quercetin 3-O-α-L-rhamnopyranosyl (1 → 6) ß-D-glucopyranoside (5) and quercetin (2) were respectively the most active compounds against bacteria (MIC = 8-64 µg/ml) and fungi (MIC = 64 - 128 µg/ml). These tested samples also showed high radical-scavenging activities (EC50 = 5.08 - 70.56 µg/ml) and gallic acid equivalent antioxidant capacities (TEAC = 53.76 - 89.86 µg/ml) when compared with vitamin C (EC50 = 4.72 µg/ml). The MeOH extract and compounds 2-5 were non-toxic to human red blood cells indicating their high selectivity to be used as antimicrobial and antioxidant drugs. CONCLUSION: The MeOH extract of O. spinosa as well as compounds 2 - 5 could be a potential source of natural antimicrobial and antioxidant products.

Antimicrobial triterpenes from the stem bark of Crossopteryx febrifuga.

Phytochemical investigation of the stem bark extract of Crossopteryx febrifuga resulted in the isolation of epimeric mixtures of 3ß-urs-12,20(30)-diene-27,28-dioic acid and 18-epi-3ß-urs-12,20(30)-diene-27,28-dioic acid (1), as well as: 3ß-D-glucopyranosylurs-12,20(30)-diene-27,28-dioic acid and 18-epi-3ß-D-glucopyranosylurs-12,20(30)-diene-27,28-dioic acid (2), together with some known compounds such as the monoglyceride of palmitic acid, as well as ß-sitosterol and its glucoside. The structures of the isolated compounds were determined by application of spectroscopic methods. The MeOH extract and compounds 1 and 2 were examined for antimicrobial activity in in vitro assays against bacteria (Enterobacter aerogenes ATCC13048, Escherichia coli ATCC8739, Klebsiella pneumoniae ATCC11296, Staphylococcus aureus) and fungi (Candida parapsilosis, Candida albicans ATCC 9002 and Cryptococcus neoformans IP 90526). The tested samples showed selective activities. The antibacterial and antifungal activities of compound 2 (MIC=8-64 µg/mL) were in some cases equal to or even higher than those of the respective reference drugs chloramphenicol (MIC=16- 64 µg/mL) and nystatin (MIC=128-256 µg/mL).

New triterpenoid saponin from the aerial part of Abrus canescens Welw ex. Bak. (Fabaceae) and their antibacterial activities.

The chemical investigation of the aerial part of Abrus canescens led to isolation of a new triterpenoid glycoside named Canescensoside (1) and four known compounds including longispinogenin-3-O-ß-D-glucuronopyranoside (2), ß-sitosterol-3-O-ß-D-glucoside (3), apigenin-7-O-ß-D-glucopyranoside (4) and apigenin-7-O-[α-L-rhamnopyranosyl-(1→3)-ß-D-glucopyranoside] (5). Structures of compounds were assigned by interpretation of their spectral data, mainly 1D and 2D NMR, HRESIMS, and by comparison with the reported data. The MeOH extract, EtOAc and n-BuOH fractions as well as isolated compounds were tested for their antibacterial activities against four bacteria strains among which, two Gram-negative (Pseudomonas aeruginosa ATCC 76110 and Escherichia coli ATCC 8739) and two Gram-positive (Enterococcus faecalis ATCC 29212 and Staphylococcus aureus ATCC 25923) bacteria using the broth microdilution method. The MeOH extract and EtOAc fraction exhibited significant activities (MIC values ranging from 128 to 512 µg/mL) against all the tested bacteria. Compounds 2 and 3 showed the lowest MIC values of 55.47 and 50.40 µM, respectively.

Synthesis, characterization, and antibacterial activity studies of two Co(II) complexes with 2-[(E)-(3-acetyl-4-hydroxyphenyl)diazenyl]-4-(2-hydroxyphenyl)thiophene-3-carboxylic acid as a ligand.

Two new Cobalt(II) complexes 12 and 13 have been synthesized from 2-[(E)-(3-acetyl-4-hydroxyphenyl)diazenyl]-4-(2-hydroxyphenyl)thiophene-3-carboxylic acid (11) as a novel ligand. These three new compounds were characterized on the basis of their powder X-Ray Diffraction, UV-Vis, IR, NMR, elemental analysis and MS spectral data. DFT/B3LYP mode of calculations were carried out to determine some theorical parameters of the molecular structure of the ligand. The purity of the azoic ligand and the metal complexes were ascertained by TLC and melting points. The analysis of the IR spectra of the polyfunctionalized azo compound 11 and its metal complexes 12 and 13, reveals that the coordination patterns of the ligand are hexadentate and tetradentate respectively. Based on the UV-Vis electronic spectral data and relevant literature reports, the ligand and derived complexes were assigned the E (trans) isomer form. Likewise, octahedral and square-planar geometries were respectively assigned to the cobalt(II) complexes. The broth microdilution method was used for antibacterial assays through the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The ligand 11 displayed moderate antibacterial activity (MIC = 32-128 µg/mL) against Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922, Pseudomonas aeruginosa and Klebsiella pneumoniae 22. The octahedral cobalt(II) complex 12 showed moderate activity against Pseudomonas aeruginosa (MIC = 128 µg/mL) and Klebsiella pneumoniae 22 (MIC = 64 µg/mL) and none against Staphylococcus aureus ATCC25923 and Escherichia coli ATCC25922, whereas the square-planar complex 13 displayed moderate activity only on Klebsiella pneumoniae 22 (MIC = 64 µg/mL).

Phytochemical Analysis, Antifungal, and Antioxidant Properties of Two Herbs (Tristemma mauritianum and Crassocephalum bougheyanum) and One Tree (Lavigeria macrocarpa) Species.

Phytochemicals present in medicinal plants (herbs, shrubs, and trees) are endowed with high antimicrobial and antioxidant properties. The aim of this work was to study the chemical composition, antioxidant, and antifungal activities of Tristemma mauritianum, Crassocephalum bougheyanum, and Lavigeria macrocarpa. Chemical composition of the plant extracts was determined using standard methods. The antioxidant activities were performed using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), nitric oxide (NO), and hydroxyl (OH) scavenging assays. The antifungal activity of plant extracts and their combinations with antifungals was evaluated against eleven Candida spp. using the broth microdilution method by determining the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). The quantitative chemical analysis of the extracts of T. mauritianum, L. macrocarpa, and C. bougheyanum showed that they contain phenols, tannins, and flavonoids that vary according to the plant species and extracts. All the plant extracts presented promising antifungal (MIC = 64-2048 µg/mL) and antioxidant activities. The extract of T. mauritianum displayed the highest antifungal (MIC = 64-256 µg/mL) and antioxidant (IC50 = 19.052 ± 1.11 µg/mL) activities which can be explained by its high phenolic content. Interestingly, extracts of T. mauritianum, L. macrocarpa, and C. bougheyanum displayed synergistic effects (fractional inhibitory concentration index, FICI ≤ 0.5) with ketoconazole against clinical resistant isolates. The results of the present study demonstrate promising antifungal and antioxidant activities of the tested plants that are associated to their phenol, tannin, and flavonoid contents. Hence, extracts of T. mauritianum and L. macrocarpa could be deeply investigated as antifungal alone and in combination with conventional antifungal drugs to treat infections caused by Candida spp.

Association of Biochemical and Hematological Parameters With Enteric Fever Infection at the Dschang Regional Annex Hospital, Cameroon: A Cross-Sectional Study.

Background Enteric fever is a systemic infection in humans caused by the Gram-negative bacilliSalmonella enterica serovars Typhi and Paratyphi. Although the diagnosis typically involves the isolation of Salmonella enterica serovars, it is often determined based on laboratory findings and clinical observations. However, due to the wide variety and the non-specific character of clinical features, making a definitive diagnosis presents numerous challenges. Therefore, the aim of this study was to find the predictive hematological and biochemical parameters which would serve in the diagnosis, prognosis, and treatment of typhoid fever cases. Methodology A cross-sectional study was conducted from November 2020 to September 2021 on1076consented volunteerparticipants. Stool culture and identification tests enabled us to distinguish three groups including 423 Salmonella Typhi positive patients, 115 S. Paratyphi positive patients, and 538 Salmonella negative participants. Biochemical and hematological parameters were evaluated using standard methods from commercial kits and Sysmex KX-21N automated hematology analyzer, respectively. A multiple logistic regression analysis was performed to identify the validity of the hematological and biochemical characteristics for enteric fever diagnosis. Results Multiple logistic regression showed hyper creatininemia, hypoalbuminemia, hyper total proteinemia, hyper alkaline phosphatase (ALP), hyper alanine aminotransferase (ALT), hyper total bilirubinemia, hyper conjugated bilirubinemia, hyper triglyceridemia, hyper C-reactive protein (CRP), leukopenia, thrombocytopenia, lymphopenia, monocytopenia, low hemoglobin, low hematocrit, low mean corpuscular volume (MCV), low mean corpuscular hemoglobin (MCH), low platelet, low platelet crit level, high platelet distribution width (PDW) level, high erythrocyte sedimentation rate 1 (ESR1) level as significant biological abnormalities associated (odds ratio {OR} > 1; p < 0.05) with enteric fever infection. Similarly, hyper ESR2 was an independent predictor (OR > 1; p < 0.05) of S. Typhi infection. However, a negative and significant association (OR < 1; p < 0.05) was recorded between enteric fever infection and high mean platelet volume (MPV). Conclusion Overall the results of the biochemical and hematological profiles can serve as potential diagnostic markers for typhoid fever. These markers can also be useful in the appropriate management of those with enteric fever, preventing severity and limiting outcomes of mortality.

A new phenolic glycoside from the leaves of Flacourtia flavescens Willd.

Chemical study of the methanol extract from the leaves of Flacourtia flavescens led to the isolation of a new phenolic glucoside (1) along with fifteen known secondary metabolites namely shanzhiside methyl ester (2), aurantiamide acetate (3), caffeic acid methyl ester (4), caffeic acid (5), apigenin (6), luteolin (7), kaempferol (8), quercetin (9), gyrophoric acid (10), luteolin-7-O-ß-D-glucopyranoside (11), luteolin-4'-O-ß-D-glucopyranoside (12), kaempferol-7-O-α-L-rhamnopyranoside (13), kaempferol-3-O-ß-D-glucopyranosyl-(1→6)-O-α-L-rhamnopyranoside (14), kaempferol-3,7-O-α-L-dirhamnopyranoside (15) and (2S,3S,4R,8E)-2-((2'R)-2'-hydroxy-octadecanoylamino)-lignocerane-1,3,4-triol-8-ene (16). Their structures were elucidated by 1D and 2D NMR analysis and mass spectrometry. The extracts and the isolated compounds were evaluated for their antibacterial activities. The EtOAc extract was highly active (MIC = 32 and 64 µg/mL) against E. coli and E. faecalis, respectively. Compounds 1, 2, 2b, 5, 8, 9, and 12 (MIC = 16-32 µg/mL) were moderately active against some tested bacteria.

Triterpene and Steroids from Ludwigia abyssinica A. Rich (Onagraceae) Displayed Antimicrobial Activities and Synergistic Effects with Conventional Antibiotics.

Difficulties encountered in treating drug-resistant pathogens have created a need for new therapies. Synergistic combinations of antibiotics are considered as ideal strategies in combating clinical and multidrug-resistant (MDR) infections. In this study, the antimicrobial activities of triterpenes and steroids from Ludwigia abyssinica A. Rich (Onagraceae) and their combined effects with antibiotics were assessed. The associations between plant constituents and antibiotics were evaluated by determining their fractional inhibitory concentrations (FICs). Sitost-5-en-3ß-ol formiate (1), 5α,6ß-dihydroxysitosterol (2), and maslinic acid (3) were isolated from the L. abyssinica ethyl acetate (EtOAc) extract. The EtOAc extract, compounds 1, 2, and 3 (MIC = 16-128 µg/mL) would be the best antibacterial and antifungal agents. The antimicrobial activities of amoxicillin were relatively weak against MDR Escherichia coli and Shigella flexneri and significant against Staphylococcus aureus ATCC 25923. However, when used in association with plant constituents, it displayed an interesting synergistic effect. Among plant components-antibiotic combinations, the EtOAc extract and compound 1 (steroid) showed a synergistic effect with amoxicillin/fluconazole against all the tested microorganisms whereas the association of compound 3 (triterpenoid) and amoxicillin/fluconazole displayed an additive effect against Shigella flexneri and Escherichia coli and a synergistic effect on Staphylococcus aureus, Cryptococcus neoformans, Candida tropicalis, and Candida albicans ATCC 10231. Overall, the results of the present study demonstrated antibacterial and antifungal activities of extracts and compounds isolated from L. abyssinica. The findings of the current study also showed that the potency of antibiotics was improved when screened in combination with L. abyssinica components, supporting the drug combination strategy to combat antimicrobial resistance.

Antibacterial stigmastane-type steroids and other constituents from the leaves of Vernonia glabra (Steetz) Vatke (Asteraceae).

Two new stigmastane steroids (1 and 2) were isolated from the methanol extract of the leaves of Vernonia glabra, together with seventeen known compounds (3-19) including one fatty acid, four triterpenoids, four steroids, one trinitropropanoyl glucoside, and seven flavonoids. The structures of compounds 1 and 2 were assigned based on their IR, NMR and MS data, and by comparison with literature values. The MeOH extract, its fractions and isolated compounds were subjected to in vitro antibacterial assay against two Gram-positive (Staphylococcus aureus ATCC25923 and Streptococcus pneumoniae ATCC49619) and two Gram-negative (Escherichia coli ATCC8739 and Klebsiella pneumoniae ATCC10031) bacteria, using broth microdilution method. The extract and fractions exhibited (16 ≤ MIC ≤ 512 µg/mL) antibacterial activities. The isolated and tested compounds were also active (16 ≤ MIC ≤ 128 µg/mL) against the four pathogenic bacteria, with compound 2 being the most active and E. coli, the most sensitive microorganism.

Antioxidant and antimicrobial activities of ethyl acetate extract, fractions and compounds from stem bark of Albizia adianthifolia (Mimosoideae).

BACKGROUND: Albizia adianthifolia is used traditionally in Cameroon to treat several ailments, including infectious and associated diseases. This work was therefore designed to investigate the antioxidant and antimicrobial activities of ethyl acetate extract, fractions and compounds isolated from the stem bark of this plant. METHODS: The plant extract was prepared by maceration in ethyl acetate. Its fractionation was done by column chromatography and the structures of isolated compounds were elucidated using spectroscopic data in conjunction with literature data. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays were used to detect the antioxidant activity. Broth micro-dilution method was used for antimicrobial test. Total phenol content was determined spectrophotometrically in the extracts by using Folin-Ciocalteu method. RESULTS: The fractionation of the extract afforded two known compounds: lupeol (1) and aurantiamide acetate (2) together with two mixtures of fatty acids: oleic acid and n-hexadecanoic acid (B1); n-hexadecanoic acid, octadecanoic acid and docosanoic acid (B2). Aurantiamide acetate was the most active compound. The total phenol concentration expressed as gallic acid equivalents (GAE) was found to vary from 1.50 to 13.49 µg/ml in the extracts. The antioxidant activities were well correlated with the total phenol content (R² = 0.946 for the TEAC method and R² = 0.980 for the DPPH free-radical scavenging assay). CONCLUSIONS: Our results clearly reveal that the ethyl acetate extract from the stem bark of A. adianthifolia possesses antioxidant and antimicrobial principles. The antioxidant activity of this extract as well as that of compound 2 are being reported herein for the first time. These results provide promising baseline information for the potential use of this plant as well as compound 2 in the treatment of oxidative damage and infections associated with the studied microorganisms.

Chemical constituents of Millettia barteri and their antimicrobial and antioxidant activities.

CONTEXT: Millettia barteri (Benth.) Dunn (Fabaceae) is an African medicinal plant used in folk medicine to treat many diseases. This species, as well as other Mellettia species, has been of interest to researchers because of their wide range of traditional uses. OBJECTIVE: Phytochemical, antimicrobial and 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH)-radical scavenging investigations of the hexane and EtOAc extracts of the stem bark of M. barteri were carried out here for the first time. MATERIALS AND METHODS: The isolation of compounds was done through silica gel column chromatography and their structures were established using spectroscopic analysis, especially, 1D NMR in conjunction with 2D experiments (COSY, HMQC and HMBC), and physical data compared with literature values. The broth micro dilution method was used for antimicrobial test while DPPH radical scavenging assay was used for antioxidant test. RESULTS: Seven compounds, including two guanidine alkaloids: millaurine (2) and milletonine (7); one flavonoid: afzelin (6); four sterols: ß-sitosterol (1), ß-sitosterol glucoside (3), mixture of stigmasterol (4) and ß-sitosterol (5) palmitates have been isolated from stem bark of hexane and ethyl acetate extracts of M. barteri. These extracts showed antimicrobial activity on the set of germs tested with minimum inhibitory concentration values varying from 64 to 512 µg/mL, as well as antioxidant activity (IC50 62.74 and 77.23 µg/mL). Compounds 2 and 7, tested for the first time, demonstrated antimicrobial and antioxidant activities. DISCUSSION AND CONCLUSIONS: The present study clearly demonstrated that M. barteri and some of its isolates possess antimicrobial and antioxidant properties and may act as potential antioxidant for biological systems susceptible to free radical-mediated reactions.

Methanol extract from the seeds of Persea americana displays antibacterial and wound healing activities in rat model.

ETHNOPHARMACOLOGICAL RELEVANCE: Persea americana Miller (Lauraceae) known as "pear" in Cameroon is comestible by the fruit. The leaves of the plant are traditionally used in the treatment of microbial infections, malaria, diabetes, high blood pressure, to stimulate uterine contractions and relief painful menstruations. The leaves and stem bark are also used to cure malaria and typhoid fever. Fresh pulps are used to lower cholesterol, prevents mental strain and cardiovascular diseases whilst the seeds are used against intestinal worms and skin infections. AIM OF THE STUDY: This study aimed to investigate the antibacterial activity and wound healing efficacy of methanol extract of Persea americana seed on an excision wound infected with Staphylococcus aureus using a rat model and characterise the mode of action of this extract. MATERIALS AND METHODS: The antibacterial activities of the methanol extract were done against a panel of bacteria using broth microdilution method. The phytochemical analysis as well as the antioxidant activities were evaluated using colorimetric methods. The mode of action of P. americana was studied by targeting bacterial membranes, cytoplasmic contents, and the formation of biofilms. The therapeutic effect of the methanol extract was evaluated on an excision wound infected with Staphylococcus aureus. RESULTS: The methanol extract of P. americana seed displayed antibacterial properties MIC varying from 64 to 128 µg/mL which can be linked to its total phenolic, flavonoid and tannin contents. The antibacterial activity of the extract is due to the bacterial biofilm inhibition and the perturbation of the bacterial membrane through the leakage of intracellular materials, the inhibition of H+-ATPases pumps. The gel based on P. americana extract showed a significant increase in the percentage of wound closure and had a significant reduction of the number of Colony Forming Units (CFU) of S. aureus at the infection site. The plant has antioxidant activity for wound healing which is lower than vitamin C. The toxicological report showed that the gel-based extract had negligible irritation on the skin and non-irritating to the eye, and therefore can be consider safe for use. CONCLUSION: The present study revealed the antibacterial and wound healing properties of the MEPa and could possibly be used to tackle bacterial infections.

Chemotaxonomy and Antibacterial Activity of the Extracts and Chemical Constituents of Psychotria succulenta Hiern. (Rubiaceae).

The use of natural products for medicinal purposes is becoming more and more common nowadays, as evidenced by the presence in plants of secondary metabolites with different potentials such as antioxidant and antibacterial properties. We evaluated in this work the antimicrobial activities of the extracts and some isolated compounds from the seeds of Psychotria succulenta Hiern. (Rubiaceae), a Cameroonian medicinal plant traditionally used to cure microbial infections. The ethanol extract was prepared by maceration and extracted with ethyl acetate and n-butanol. The EtOAc (m = 168 g) and n-BuOH (m = 20 g) extracts were further fractionated by silica gel column chromatography to isolation of compounds. Their structures were elucidated by spectroscopic analysis and by comparison with published data. The antibacterial activity of extracts and compounds was assessed by evaluating the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against pathogenic bacteria. Thirteen compounds including four alkaloids (veprisine (1), naucleofficine III (2), vepridimerine B (3), and vepridimerine C (4)), three triterpenes (barbinervic acid (5), 3-O-α-L-rhamnopyranosyl quinovic acid (6), and oleanolic acid (7)), one steroid (ß-sitosterol-3-O-ß-D-glucopyranoside (8)), four phenolic compounds (scopoletin (9), gallic acid (10), quercetin-3-O-ß-D-glucopyranoside (11), and kaempferol 3-O-α-L-rhamnopyranoside-7-O-α-L-rhamnopyranoside (12)), and one iridoid (borreriagenin (13)) were isolated from the EtOAc and n-BuOH extracts. These compounds were identified by 1D and 2D NMR combined analysis as well as by melting point comparison. The EtOH, EtOAc, and n-BuOH extracts exhibited significant antibacterial activities (MIC = 32-128 µg/mL; MBC = 64-256 µg/mL) against Staphylococcus aureus (Gram-positive bacterium), Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumonia (Gram-negative bacteria). Among the isolated compounds, scopoletin (9) showed a moderate activity against Klebsiella pneumoniae with MIC and MBC values of 16 µg/mL and 32 µg/mL, respectively. It appears that, chemotaxonomically, some of the isolated compounds have already been obtained from the genus Psychotria but to the best of our knowledge, this is the first report on the phytochemical investigation of P. succulenta. Although many other studies need to be achieved, our results support the use of P. succulenta in traditional medicine to cure infectious diseases particularly those caused by the tested bacteria.