Echinograciolide, a new antibacterial nor-triterpenoid and other constituents from Echinops gracilis O. Hoffm. (Asteraceae)

Antibacterial resistance is a serious threat against humankind and the search for new therapeutics is needed. This study aims to investigate the antibacterial activity of extracts and compounds from Echinops gracilis O. Hoffm. Standard chromatographic and spectroscopic methods were used to isolate and characterize compounds (1-15) from the methanol extract. The extract, chromatographic fractions and compounds 1-3, 8, 11, 13 and 14 were subjected to in vitro antibacterial assays against Staphylococcus aureus ATCC25923, Salmonella Typhi ATCC6539, Klebsiella pneumoniae 22, and Salmonella Typhi 68, using broth micro-dilution method. As results, a new nor-triterpenoid (1) and fourteen known compounds (2-15) were characterized. The extract and fractions displayed moderate (128 ≤ MIC ≤ 512 μg/mL) and significant (MIC 64 μg/mL) antibacterial activities. Compounds 1 and 14 showed the best anti-staphylococcal and anti-salmonella activity (MIC 16 µg/mL), respectively. These results partially justified the antimicrobial uses of E. gracilis in traditional medicine.

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-β-D-glucuronopyranoside (2), β-sitosterol-3-O-β-D-glucoside (3), apigenin-7-O-β-D-glucopyranoside (4) and apigenin-7-O-[α-L-rhamnopyranosyl-(1→3)-β-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.

Two new flavone glycosides from the leaves of Ochna afzelii Oliv. (Ochnaceae)

Two new glycosylflavones, 6''-O-acetyl-8-C-β-D-galactopyranosylchrysoeriol (1) and 8-C-β-D-galactopyranosylchrysoeriol (2) were isolated from the methanol extract of the leaves of Ochna afzelii Oliv., along with four known compounds namely 8-C-β-D-galactopyranosylapigenin (3), ochnaflavone (4), sitosterol-3-O-β-D-glucopyranoside (5) and D-mannitol (6). Isolation was performed chromatographically and the structures of the purified compounds were elucidated by analyzing their spectroscopic and mass spectrometric data. The antibacterial activity of extract, fractions, and compounds 1 - 4 was evaluated using broth microdilution method against Gram-positive and Gram-negative bacteria while the antioxidant capacity was performed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the ferric reducing antioxidant power (FRAP) methods. The new flavones (1 and 2) displayed moderate antibacterial activities (MIC = 32 - 64 µg/mL) and weak antioxidant properties.

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.

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-β-D-glucopyranoside (11), luteolin-4'-O-β-D-glucopyranoside (12), kaempferol-7-O-α-L-rhamnopyranoside (13), kaempferol-3-O-β-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.

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 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.

A new megastigmane, known porphyrinic and galloylated bioactive derivatives from the leaves of Gymnosporia senegalensis

Investigation of the non-polar (rich in chlorophyll) and polar fractions of the ethyl acetate extract of Gymnosporia senegalensis (Lam.) Loes. leaves led to the isolation of nine compounds, including one new megastigmane derivative, (3 R*,5 S*,6 R*,7 E,9ξ)-7-megastigmene-3,6,9-triol-3- O-β-D-(6′- O-galloyl)glucopyranoside (1), four known galloylated derivatives (2, 3, 8, 9), three known chlorophyll derivatives (4–6), and one known fatty acid (7). The structures of the isolates were determined by means of spectroscopic and spectrometric data, as well as by comparison with literature values. The extracts and isolated compounds were tested for their antibacterial, antifungal, and antioxidant activities. The isolates showed weak to high antimicrobial activities with phaeophytin A (4) being the most active one whereas phaeophorbide-a (5) and Chlorine e6 trimethyl ester (6) exhibited the highest antioxidant activities.

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.

A new antimicrobial nor-friedelane-type triterpenoid and other constituents from Plectranthus glandulosus Hook. f. (Lamiaceae)

Chemical investigation of the ethanol extract from the whole plant of Plectranthus glandulosus led to the isolation of a new nor-triterpenoid (1) along with seventeen known compounds (2-18) including seven triterpenoids, nine flavonoids and one steroid. Their structures were established on the basis of 1D- and 2D-NMR, IR, and MS experiments, and by comparison of their spectroscopic data with those of similar compounds reported in the literature. The EtOH extract and some isolated triterpenoids (1-4 and 13) were subjected to in vitro antimicrobial assays against a panel of pathogenic microorganisms, including Gram-positive and Gram-negative bacteria, and fungi using broth microdilution method. The EtOH extract displayed moderate activity (MIC = 512 µg/mL) against Staphylococcus aureus MSSA1, Shigella flexneri SDINT and Cryptococcus neoformans H99. Compounds 1, 4 and 13 showed the most potent antimicrobial effect with MICs of 32-256 µg/mL.

Antibacterial and Therapeutic Potentials of the Capsicum annuum Extract against Infected Wound in a Rat Model with Its Mechanisms of Antibacterial Action

The wound healing process is essential to reform the damaged tissue and prevent its invasion by pathogens. The present study aims at evaluating the antibacterial and therapeutic properties of the Capsicum annuum L. (Solanaceae) extract against infected wound in a rat model with its mechanisms of antibacterial action. The fruit extract was prepared by maceration in methanol. The broth microdilution method was used to investigate the antibacterial activity of the methanol extract of C. annuum fruits. The therapeutic effect of the extract gel was performed on an excision wound infected with Staphylococcus aureus using a rat model. The total phenol, flavonoid, and tannin contents as well as the antibacterial mechanisms of action of the extract were determined using spectrophotometric methods. The C. annuum fruit extract showed antibacterial properties which can be linked to its total phenolic, flavonoid, and tannin contents. The antibacterial activity is due to the inhibition of the biofilm formation, ATPases/H+ proton pump, and dehydrogenase activity as well as the alteration of the bacterial cell membrane through the leakage of nucleic acids, reducing sugars and proteins. The extract gel showed a significant (p < 0.05) increase in the percentage of wound closure and eradicated S. aureus at the infection site. The extract gel was nonirritating to the skin and slightly irritating to the eyes and should be used with caution. Overall, the findings of the present study support the traditional use of the studied plant in the treatment of wounds and infectious diseases associated with the tested bacteria.

Antibacterial, antifungal and antioxidant activities of whole plant chemical constituents of Rumex abyssinicus

Background

Antibiotic resistance has contributed to the burden of infectious diseases both in the hospital and community setting, and represents a great threat to public health. Previous studies have revealed the role of reactive oxygen species as intermediate mediators of tissue damage, following antibiotherapies, indicating the need of associating antioxidants to these treatments. Therefore, the present work was designed to study the antibacterial, antifungal and antioxidant activities of extracts and compounds from Rumex abyssinicus Jacq. (Polygonaceae), as well as to investigate the antibacterial mechanisms of action of the most effective agents.

Methods

The plant extracts were prepared by maceration in organic solvents followed by column chromatography of the EtOAc fraction and purification of different fractions which led to the isolation and characterization of pure compounds. The antimicrobial activities of the extracts/compounds and their combinations with ciprofloxacin and fluconazole were evaluated using the broth microdilution method by determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC). The effects of the extracts on the bacterial cell membrane and microbial respiratory chain dehydrogenase enzyme activity were determined by spectrophotometric methods. Antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and gallic acid equivalent antioxidant capacity (GAEAC) assays.

Results

Chrysophanol (1), physcion (2), Ergosta-6,22-diene-3,5,8-triol (3), emodin (4), 6-hydroxyemodin (citreorosein) (5), chrysophanein (6) and physcionin (7) were isolated from EtOAc fraction of R. abyssinicus and displayed different degrees of antimicrobial activities (MIC = 8–256 μg/mL). The MeOH extract and compounds 2 and 4 exhibited synergistic effects with ciprofloxacin and fluconazole. Compounds 1, 2 and the combined mixture of 6 + 7 displayed the highest antioxidant activity (GAEAC = 83.38–106.03 μg/mL).

Conclusion

R. abyssinicus is a potential source of antibacterial, antifungal and antioxidant agents. The antibacterial mechanisms of action of the MeOH extract and compound 2 are due to disruption of the cytoplasmic membrane and inhibition of the microbial respiratory chain dehydrogenase enzyme activity. To the best of our knowledge, this is the first report of test samples and ciprofloxacin / fluconazole association against MDR strains. The observed activity of the isolated compounds against bacteria and fungi including MDR strains deserves further exploration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03325-y.