The present work was designed to investigate the antibacterial activities of methanol extracts from six Cameroonian edible plants and their synergistic effects with some commonly used antibiotics against multidrug-resistant (MDR) Gram-negative bacteria expressing active efflux pumps. The extracts were subjected to qualitative phytochemical screening and the microdilution broth method was used for antibacterial assays. The results of phytochemical tests indicate that all tested crude extracts contained polyphenols, flavonoids, triterpenes, and steroids. Extracts displayed selective antibacterial activities with the minimal inhibitory concentration (MIC) values ranging from 32 to 1024
The discovery of antibiotics has inevitably fostered the development and emergence of resistances in bacteria, regardless of the mechanism of action of the antibiotic involved. For decades, and in order to reduce the development and epidemic spread of resistance, physicians and scientists have called for appropriate use of antibiotics [
The plant materials used in this work were collected in the period of March to April 2015 in two regions of Cameroon and included leaves and bark of
Plants used in the present study and evidence of their bioactivities.
Species (family); |
Traditional uses | Parts used traditionally | Bioactive or potentially bioactive components | Bioactivity of crude extract |
---|---|---|---|---|
|
To treat wounds, lesions, ulcers, diarrhea, cholera, hypertension, and obesity and the control of diabetes mellitus [ |
Leaves, fruits, flowers, bark, and roots | Tannins, flavonoids (myricetin, quercetin, luteolin and kaempferol), essential oils (caryophyllene, nerolidol, |
|
|
||||
|
Anticancer activity, the food industry has grown tremendous interest in processing this crop and enhancing its value [ |
Leaves, fruit, flowers, bark, and roots |
|
|
|
||||
|
Treat ailments like constipation, cramps, colic, diarrhea, bronchitis, tuberculosis, cough, cold, obesity, menstrual disorder, angina, hypertension, anxiety, depression, and stress [ |
Leaves, flowers, seeds, peel, fruits, and barks | Polyphenols (caffeic acid, p-coumaric acid, ferulic acid, and sinapinic acid), flavonoids (hesperidin, narirutin, naringin, eriocitrin) [ |
|
|
||||
|
The stomachic bark decoction is used to treat dysentery in Liberia and the bark powder decoction is used in equatorial Africa to stimulate appetite and counteract anemia [ |
Leaves, stem bark, fruits, and roots |
|
|
|
||||
|
Anti-syphilitic, vulnerary, antiemetic, anti-inflammatory, cough, hiccup, hyperdipsia, burning sensation, hemorrhages, haemoptysis, hemorrhoids, wounds, ulcers, diarrhoea, dysentery, pharyngopathy, scorpion string, wounds, ulcers, anorexia, and dyspepsia [ |
Leaves, flowers, barks, roots, stones, and fruits | Carotenoids (provitamin A compound, beta-carotene, lutein, and alpha-carotene), polyphenols [ |
|
|
||||
|
Aiding digestion, blood purification, ensuring regularity, lowering body temperature, strengthening teeth and bones, boosting immune system, enhancing heart function, suppressing aging, deterring food poisoning, fighting virus, and lowering blood sugar levels [ |
Leaves, stem, bark, and roots | Polyphenols (catechins and their derivatives), methylxanthines (caffeine, theophylline and theobromine), carbohydrates, proteins, free amino acids, vitamins (vitamin C and carotenoids), volatile compounds, lipids, chlorophylls, saponins and inorganic elements (fluorine, manganese and aluminum) [ |
|
The major phytochemical classes such as alkaloids (Dragendorff’s and Mayer’s tests), triterpenes (Liebermann-Burchard’s test), flavonoids (aluminum chloride test), anthraquinones (Borntrager’s test), polyphenols (ferric chloride test), sterols (Salkowski’s test), coumarins (lactone test), saponins (foam test), and tannins (gelatin test) (Table
Extraction yields, aspects, and phytochemical composition of the plant extracts.
Extracts |
|
|
|
|
|
|
||||
---|---|---|---|---|---|---|---|---|---|---|
Parts used | Leaves | Bark | Fruits | Leaves | Bark | Peel | Fruits | Leaves | Bark | Leaves |
|
5.47 | 4.17 | 6.12 | 5.15 | 4.47 | 6.56 | 7.25 | 5.36 | 4.26 | 5.8 |
Alkaloids | + | + | − | + | + | + | + | + | + | + |
Polyphenols | + | + | + | + | + | + | + | + | + | + |
Flavonoids | + | + | + | + | + | + | + | + | + | + |
Anthraquinones | − | − | − | + | + | − | + | + | + | − |
Coumarins | + | + | + | + | + | + | + | + | + | − |
Tannins | + | + | − | + | + | + | + | + | + | + |
Triterpenes | + | + | + | + | + | + | + | + | + | + |
Sterols | + | + | + | + | + | + | + | + | + | + |
Saponins | + | + | − | + | + | + | + | + | + | + |
−: absent; +: present;
The studied bacteria strains included reference (from American Type Culture Collection) and clinical (Laboratory collection) strains of
The reference antibiotics used in the present work included tetracycline (TET), cefepime (CEP), ciprofloxacin (CIP), streptomycin (STP), chloramphenicol (CHL), ampicillin (AMP), erythromycin (ERY), and kanamycin (KAN), all provided by Sigma-Aldrich, St Quentin Fallavier, France.
Rapid INT colorimetric assay [
The role of efflux pumps in the susceptibility of Gram-negative bacteria to
To evaluate the potentiating effect of tested extracts, a preliminary combination at their subinhibitory concentrations (MIC/2, MIC/4, MIC/8, and MIC/16) with antibiotics was assessed against
The results of the phytochemical screening (Table
The antibacterial activities of plants’ extracts alone and in some cases, in the presence of the PA
Minimal inhibitory concentration (MIC) in
Bacterial strains | Tested samples and MIC and MBC and MIC in the presence of PA | ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
|
|||||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||||||||
|
512 | — | — | 1024 | — | — | 1024 | — | — | 256 | — | — | 256 | — | — |
|
512 | — | — | 1024 | — | — | 512 | — | — | 128 | — | — | 256 | — | — |
|
1024 | — | — | 1024 | — | — | 512 | — | — | 256 | — | — | 256 | — | — |
|
256 (256) | — | — | 512 | — | — | 1024 | — | — | 256 (256) | — | — | 512 (512) | — | — |
|
512 (512) | — | — | 256 | 1024 | 4 | 1024 | — | — |
|
512 | 8 | 128 (64) | 1024 | 8 |
|
512 (128) | — | — | — | — | — | 1024 | — | — | 512 (128) | — | — | 512 (128) | — | — |
|
512 | — | — | — | — | — | 1024 | — | — | 128 | — | — | 512 | — | — |
|
1024 | — | — | — | — | — | 1024 | — | — | 256 | — | — | 256 | — | — |
|
|||||||||||||||
|
|||||||||||||||
|
256 | — | — | 1024 | — | — | 512 | — | — | 512 | — | — | 512 | — | — |
|
512 (512) | — | — | — | — | — | 1024 | — | — | 512 (512) | — | — | 512 (512) | — | — |
|
512 | — | — | — | — | — | 512 | — | — | 256 | — | — | 128 | — | — |
|
128 (128) | — | — | — | — | — | — | — | — | 128 (256) | — | — | 256 (256) | — | — |
|
256 (128) | — | — | — | — | — | 512 | — | — | 256 (256) | — | — | 512 (512) | — | — |
|
1024 | — | — | — | — | — | — | — | — | 256 | — | — | 128 | 1024 | 8 |
|
1024 (1024) | — | — | — | — | — | — | — | — | 128 (128) | 1024 |
|
256 (256) | 1024 | 4 |
|
|||||||||||||||
|
|||||||||||||||
|
1024 | — | — | — | — | — | — | — | — | 512 | — | — | 1024 | — | — |
|
512 | — | — | 1024 | — | — | 1024 | — | — | 256 | — | — | 256 | — | — |
|
512 | — | — | — | — | — | 1024 | — | — | 512 | — | — | 512 | — | — |
|
1024 (1024) | — | — | 1024 | — | — | 512 | — | — | — (—) | — | — | — (—) | — | — |
|
256 (16) | — | — | — | — | — | 512 | — | — | 512 (<8) | — | — | 128 (<8) | 1024 | 8 |
|
|||||||||||||||
|
|||||||||||||||
|
512 | — | — | — | — | — | 1024 | — | — | — | — | — | — | — | — |
|
512 | — | — | 1024 | — | — | 1024 | — | — | 512 | — | — | 1024 | — | — |
|
512 (512) | — | — | 512 | 1024 |
|
512 | — | — | 256 (256) | 1024 |
|
512 (512) | — | — |
|
1024 (1024) | — | — | — | — | — | 512 | 1024 |
|
1024 (512) | — | — | 256 (16) | 1024 |
|
|
|||||||||||||||
|
|||||||||||||||
|
256 (1024) | — | — | — | — | — | 512 | — | — | 512 (512) | — | — | 128 (128) | — | — |
|
256 (256) | — | — | 1024 | — | — | 512 | — | — | 512 (512) | — | — | 256 (256) | — | — |
|
512 (512) | — | — | — | — | — | 512 | — | — | 1024 (1024) | — | — | — (—) | — | — |
|
|||||||||||||||
|
|||||||||||||||
|
512 | — | — | — | — | — | 1024 | — | — | — | — | — | 128 | — | — |
|
1024 (1024) | — | — | — | — | — | 1024 | — | — | — (—) | — | — | 1024 (512) | — | — |
Bacterial strains | Tested samples and MIC and MBC and MIC in the presence of PA | ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
|
|||||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||||||||
|
|
256 | 4 | — |
|
|
256 |
|
|
512 |
|
|
|
256 | 4 |
|
256 | — | — | 512 |
|
|
256 |
|
|
512 |
|
|
|
512 | 8 |
|
128 | — | — | 1024 |
|
|
— |
|
|
512 |
|
|
|
|
|
|
512 (256) |
|
— | 1024 |
|
|
— (—) |
|
|
512 (256) |
|
|
1024 |
|
|
|
128 (<8) | 1024 | 4 | 1024 (1024) |
|
|
1024 (1024) |
|
|
256 (256) |
|
|
|
256 | 8 |
|
512 (8) |
|
— | 1024 (1024) |
|
|
— (—) |
|
|
256 (256) |
|
|
1024 |
|
|
|
|
|
— | 1024 |
|
|
1024 |
|
|
1024 |
|
|
|
|
|
|
|
512 | 16 | 1024 |
|
|
1024 |
|
|
1024 |
|
|
|
|
|
|
|||||||||||||||
|
|||||||||||||||
|
512 | 1024 | 2 | 512 |
|
|
512 |
|
|
512 |
|
|
512 |
|
|
|
— (16) |
|
— | — (1024) |
|
|
— (—) |
|
|
— (—) |
|
|
|
|
|
|
256 |
|
— | 1024 |
|
|
512 |
|
|
1024 |
|
|
128 |
|
|
|
512 (256) |
|
— | 512 (256) |
|
|
512 (256) |
|
|
1024 (1024) |
|
|
256 |
|
|
|
512 (<8) |
|
— | — (—) |
|
|
512 (—) |
|
|
512 (64) |
|
|
512 |
|
|
|
128 | 512 | 4 | — |
|
|
— |
|
|
1024 |
|
|
|
1024 | 16 |
|
128 (128) | 512 | 4 | — (—) |
|
|
— (—) |
|
|
512 (512) |
|
|
256 |
|
|
|
|||||||||||||||
|
|||||||||||||||
|
512 |
|
|
— |
|
|
— |
|
|
512 |
|
|
|
|
|
|
128 |
|
|
1024 |
|
|
1024 |
|
|
|
|
|
|
|
|
|
|
|
|
1024 |
|
|
1024 |
|
|
512 |
|
|
1024 |
|
|
|
— (—) |
|
|
1024 (1024) |
|
|
1024 (1024) |
|
|
— (—) |
|
|
1024 |
|
|
|
256 (<8) |
|
|
1024 (1024) |
|
|
512 (256) |
|
|
256 (64) |
|
|
512 |
|
|
|
|||||||||||||||
|
|||||||||||||||
|
|
|
|
512 |
|
|
1024 |
|
|
512 |
|
|
|
|
|
|
|
|
|
1024 |
|
|
— |
|
|
512 |
|
|
128 | 1024 | 8 |
|
1024 (<8) |
|
|
512 (512) |
|
|
512 (512) |
|
|
— (—) |
|
|
512 | 512 | 1 |
|
128 (16) | 1024 | 8 | 512 (512) |
|
|
512 (512) |
|
|
1024 (1024) | 1024 |
|
128 | 1024 | 8 |
|
|||||||||||||||
|
|||||||||||||||
|
256 (16) |
|
|
512 |
|
|
512 (512) |
|
|
1024 (1024) |
|
|
1024 |
|
|
|
512 (512) |
|
|
1024 |
|
|
512 (512) |
|
|
256 (256) | 1024 | 4 |
|
|
|
|
512 (512) |
|
|
— (—) |
|
|
512 (256) | — |
|
|
|
|
|||
|
|||||||||||||||
|
|||||||||||||||
|
128 | 512 | 4 | 1024 |
|
|
|
|
|
512 |
|
|
|
|
|
|
— (1024) |
|
|
1024 (512) |
|
|
512 (512) |
|
|
1024 (1024) |
|
|
|
|
|
Bacterial strains |
|
||
---|---|---|---|
MIC | MBC |
|
|
|
|||
|
4 | 16 | 4 |
|
4 | 128 | 32 |
|
8 | 64 | 8 |
|
64 | — | — |
|
64 | 256 | 4 |
|
128 | — | — |
|
8 | 64 | 8 |
|
8 | 256 | 32 |
|
|||
|
|||
|
8 | 64 | 8 |
|
128 | — | — |
|
32 | 256 | 8 |
|
128 | — | — |
|
256 | — | — |
|
8 | 128 | 16 |
|
32 | 64 | 2 |
|
|||
|
|||
|
64 | — | — |
|
32 | 128 | 4 |
|
128 | 256 | 2 |
|
64 | 128 | 2 |
|
64 | 256 | 4 |
|
|||
|
|||
|
128 | — | — |
|
64 | 256 | 4 |
|
128 | — | — |
|
32 | 256 | 8 |
|
|||
|
|||
|
256 | — | — |
|
128 | — | — |
|
— | 256 | — |
|
|||
|
|||
|
32 | — | — |
|
256 | — | — |
Fifteen of the studied MDR bacteria were also tested for their susceptibility to plant extracts in the presence of the PA
A preliminary study performed against
MIC of different antibiotics after the association of the extract of
Antibiotic |
Bacterial strains and MIC ( |
|||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Extract |
PA124 | AG102 | AG100Atet | EA289 | CM64 | KP55 | KP63 | NEA16 | PS2636 | BM47 | PBS |
|
CHL | 0 | 128 | 8 | 128 | 256 | 256 | 32 | 32 | 16 | 64 | 128 | |
MIC/2 |
|
< |
|
256 (1)I |
|
32 (1)I |
|
16 (1)I |
|
128 (1)I |
|
|
MIC/4 | 128 (1)I | < |
128 (1) |
256 (1) |
|
32 (1) |
|
16 (1) |
64 (1) |
128 (1) |
30 | |
|
||||||||||||
CIP | 0 | 64 | 2 | >64 | >64 | >64 | 2 | <0.5 | 4 | 8 | <0.5 | |
MIC/2 |
|
|
>64 (≥1) |
|
|
|
<0.5 ( |
4 (1) |
< |
<0.5 ( |
|
|
MIC/4 |
|
|
>64 (≥1) |
>64 (≥1) |
|
|
<0.5 ( |
4 (1) |
|
<0.5 ( |
|
|
|
||||||||||||
TET | 0 | 16 | 16 | 32 | 64 | 4 | 32 | 2 | 4 | 2 | 32 | |
MIC/2 |
|
< |
64 (2) |
64 (1) |
|
32 (1) |
2 (1) |
4 (1) |
< |
32 (1) |
40 | |
MIC/4 |
|
< |
64 (2) |
64 (1) |
|
32 (1) |
2 (1) |
4 (1) |
< |
32 (1) |
40 | |
|
||||||||||||
ERY | 0 | 128 | 8 | 128 | 256 | 8 | 16 | 4 | 16 | 16 | 16 | |
MIC/2 | 128 (1)I | < |
128 (1) |
256 (1) |
8 (1) |
16 (1) |
< |
16 (1) |
|
16 (1) |
30 | |
MIC/4 | 128 (1)I | < |
128 (1) |
256 (1) |
8 (1) |
16 (1) |
< |
16 (1) |
16 (1) |
16 (1) |
20 | |
|
||||||||||||
KAN | 0 | 128 | 4 | 8 | 32 | 32 | 32 | <2 | 16 | 16 | 8 | |
MIC/2 | 128 (1)I | < |
8 (1) |
|
|
32 (1) |
<2 ( |
|
16 (1) |
8 (1) |
|
|
MIC/4 | 128 (1)I | < |
8 (1) |
|
|
32 (1) |
<2 ( |
|
16 (1) |
8 (1) |
|
|
|
||||||||||||
STP | 0 | 256 | >256 | >256 | 128 | 8 | 64 | 8 | 16 | >256 | 64 | |
MIC/2 |
|
|
< |
128 (1) |
< |
|
< |
16 (1) |
< |
|
|
|
MIC/4 |
|
|
< |
128 (1) |
8 (1) |
|
< |
16 (1) |
|
64 (1) |
|
|
|
||||||||||||
AMP | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 | >256 (≥1)I | < |
>256 (≥1) |
>256 (≥1) |
< |
>256 (≥1) |
< |
< |
< |
>256 (≥1) |
|
|
MIC/4 | >256 (≥1)I | < |
>256 (≥1) |
>256 (≥1) |
< |
>256 (≥1) |
|
< |
< |
>256 (≥1) |
|
|
|
||||||||||||
CEF | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 | >256 (≥1)I | >256 (≥1)I | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
< |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
10 | |
MIC/4 | >256 (≥1)I | >256 (≥1)I | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
|
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
10 |
MIC of different antibiotics after the association of the extract of
Antibiotic |
Bacterial strains and MIC ( |
|||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Extract |
PA124 | AG102 | AG100Atet | EA289 | CM64 | KP55 | KP63 | NEA16 | PS2636 | BM47 | PBS |
|
CHL | 0 | 128 | 8 | 128 | 256 | 256 | 32 | 32 | 16 | 64 | 128 | |
MIC/2 |
|
< |
128 (1) |
256 (1) |
|
32 (1) |
32 (1) |
16 (1) |
|
128 (1) |
40 | |
MIC/4 |
|
|
128 (1) |
256 (1) |
|
32 (1) |
32 (1) |
16 (1) |
|
128 (1) |
40 | |
|
||||||||||||
CIP | 0 | 64 | 2 | >64 | >64 | >64 | 2 | <0.5 | 4 | 8 | <0.5 | |
MIC/2 |
|
< |
>64 (≥1) |
|
|
2 (1) |
<0.5 (≤1) |
< |
< |
<0.5 (≤1) |
|
|
MIC/4 |
|
< |
>64 (≥1) |
|
|
2 (1) |
<0.5 (≤1) |
< |
< |
<0.5 (≤1) |
|
|
|
||||||||||||
TET | 0 | 16 | 16 | 32 | 64 | 4 | 32 | 2 | 4 | 2 | 32 | |
MIC/2 | 16 (1) |
< |
64 (2) |
64 (1) |
< |
32 (1) |
2 (1) |
4 (1) |
< |
32 (1) |
30 | |
MIC/4 | 16 (1) |
< |
64 (2) |
64 (1) |
< |
32 (1) |
2 (1) |
4 (1) |
< |
32 (1) |
20 | |
|
||||||||||||
ERY | 0 | 128 | 8 | 128 | 256 | 8 | 16 | 4 | 16 | 16 | 16 | |
MIC/2 | 128 (1) |
< |
128 (1) |
256 (1) |
16 (2) |
16 (1) |
4 (1) |
|
|
16 (1) |
30 | |
MIC/4 | 128 (1) |
< |
128 (1) |
256 (1) |
16 (2) |
16 (1) |
4 (1) |
|
16 (1) |
16 (1) |
20 | |
|
||||||||||||
KAN | 0 | 128 | 4 | 8 | 32 | 32 | 32 | <2 | 16 | 16 | 8 | |
MIC/2 | 128 (1) |
< |
8 (1) |
32 (1) |
32 (1) |
32 (1) |
<2 (≤1) |
16 (1) |
16 (1) |
8 (1) |
0 | |
MIC/4 | 128 (1) |
< |
8 (1) |
32 (1) |
32 (1) |
32 (1) |
<2 (≤1) |
16 (1) |
16 (1) |
8 (1) |
20 | |
|
||||||||||||
STP | 0 | 256 | >256 | >256 | 128 | 8 | 64 | 8 | 16 | >256 | 64 | |
MIC/2 |
|
|
< |
128 (1) |
128 (16) |
64 (1) |
8 (1) |
16 (1) |
|
64 (1) |
40 | |
MIC/4 |
|
>256 (≥1) |
|
128 (1) |
128 (16) |
64 (1) |
8 (1) |
16 (1) |
|
64 (1) |
30 | |
|
||||||||||||
AMP | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 |
|
< |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
< |
< |
>256 (≥1) |
40 | |
MIC/4 | >256 (≥1) |
< |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
< |
< |
>256 (≥1) |
30 | |
|
||||||||||||
CEF | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
00 | |
MIC/4 | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
00 |
MIC of different antibiotics after the association of the extract of leaves from
Antibiotic |
Bacterial strains and MIC ( |
|||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Extract |
PA124 | AG102 | AG100Atet | EA289 | CM64 | KP55 | KP63 | NEA16 | PS2636 | BM47 | PBS |
|
CHL | 0 | 128 | 8 | 128 | 256 | 256 | 32 | 32 | 16 | 64 | 128 | |
MIC/2 |
|
< |
|
|
|
|
|
|
|
|
|
|
MIC/4 |
|
|
|
|
|
32 (1) |
32 (1) |
|
64 (1) |
128 (1) |
|
|
|
||||||||||||
CIP | 0 | 64 | 2 | >64 | >64 | >64 | 2 | <0.5 | 4 | 8 | <0.5 | |
MIC/2 |
|
< |
|
|
|
2 (1) |
<0.5 (≥1) |
< |
< |
<0.5 (≥1) |
|
|
MIC/4 |
|
< |
>64 (≥1) |
|
|
2 (1) |
<0.5 (≥1) |
|
|
<0.5 (≥1) |
|
|
|
||||||||||||
TET | 0 | 16 | 16 | 32 | 64 | 4 | 32 | 2 | 4 | 2 | 32 | |
MIC/2 | 32 (2) |
|
|
< |
|
|
|
< |
< |
|
|
|
MIC/4 | 32 (2) |
|
|
|
|
|
|
< |
< |
|
|
|
|
||||||||||||
ERY | 0 | 128 | 8 | 128 | 256 | 8 | 16 | 4 | 16 | 16 | 16 | |
MIC/2 | 128 (1) |
< |
|
|
|
|
< |
|
< |
< |
|
|
MIC/4 | 128 (1) |
< |
|
|
|
16 (1) |
< |
|
|
|
|
|
|
||||||||||||
KAN | 0 | 128 | 4 | 8 | 32 | 32 | 32 | <2 | 16 | 16 | 8 | |
MIC/2 | 128 (1) |
< |
|
< |
|
|
<2 (≥1) |
< |
|
8 (1) |
|
|
MIC/4 | 128 (1) |
< |
8 (1) |
|
|
|
<2 (≥1) |
|
16 (1) |
8 (1) |
|
|
|
||||||||||||
STP | 0 | 256 | >256 | >256 | 128 | 8 | 64 | 8 | 16 | >256 | 64 | |
MIC/2 |
|
|
|
|
|
|
|
|
|
|
|
|
MIC/4 |
|
|
|
|
8 (1) |
|
8 (1) |
16 (1) |
>256 (na) |
|
|
|
|
||||||||||||
AMP | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 |
|
|
|
|
|
|
|
|
|
>256 (≥1) |
|
|
MIC/4 | >256 (≥1) |
|
|
|
|
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
40 | |
|
||||||||||||
CEF | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 |
|
|
>256 (≥1) |
|
|
>256 (≥1) |
>256 (≥1) |
|
>256 (≥1) |
>256 (≥1) |
|
|
MIC/4 | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
|
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
10 |
MIC of different antibiotics after the association of the extract of leaves from
Antibiotic |
Bacterial strains and MIC ( |
|||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Concentration of the extract | PA124 | AG102 | AG100Atet | EA289 | CM64 | KP55 | KP63 | NEA16 | PS2636 | BM47 | PBS |
|
CHL | 0 | 128 | 8 | 128 | 256 | 256 | 32 | 32 | 16 | 64 | 128 | |
MIC/2 |
|
|
|
256 (1) |
256 (1) |
32 (1) |
|
|
|
|
|
|
MIC/4 |
|
8 (1) |
128 (1) |
256 (1) |
256 (1) |
32 (1) |
32 (1) |
16 (1) |
64 (1) |
128 (1) |
10 | |
|
||||||||||||
CIP | 0 | 64 | 4 | >64 | >64 | >64 | 2 | <0.5 | 4 | 8 | <0.5 | |
MIC/2 |
|
4 (1) |
>64 (≥1) |
|
|
2 (1) |
<0.5 (≥1) |
|
|
<0.5 (≥1) |
|
|
MIC/4 |
|
4 (1) |
>64 (≥1) |
>64 (≥1) |
|
2 (1) |
<0.5 (≥1) |
4 (1) |
|
<0.5 (≥1) |
30 | |
|
||||||||||||
TET | 0 | 16 | 16 | 32 | 64 | 4 | 32 | 2 | 4 | 2 | 32 | |
MIC/2 | 32 (2) |
|
32 (1) |
|
4 (1) |
|
< |
< |
< |
|
|
|
MIC/4 | 32 (2) |
16 (1) |
32 (1) |
|
4 (1) |
32 (1) |
|
4 (1) |
< |
32 (1) |
30 | |
|
||||||||||||
ERY | 0 | 128 | 8 | 128 | 256 | 8 | 16 | 4 | 16 | 16 | 16 | |
MIC/2 | 128 (1) |
|
128 (1) |
|
< |
16 (1) |
|
16 (1) |
16 (1) |
|
|
|
MIC/4 | 128 (1) |
|
128 (1) |
|
< |
16 (1) |
4 (1) |
16 (1) |
16 (1) |
16 (1) |
10 | |
|
||||||||||||
KAN | 0 | 128 | 4 | 8 | 32 | 32 | 32 | <2 | 16 | 16 | 8 | |
MIC/2 | 128 (1) |
< |
8 (1) |
|
32 (1) |
|
<2 (≥1) |
|
|
8 (1) |
|
|
MIC/4 | 128 (1) |
< |
8 (1) |
32 (1) |
32 (1) |
32 (1) |
<2 (≥1) |
|
16 (1) |
8 (1) |
20 | |
|
||||||||||||
STP | 0 | 256 | >256 | >256 | 128 | 8 | 64 | 8 | 16 | >256 | 64 | |
MIC/2 |
|
|
|
128 (1) |
|
64 (1) |
|
16 (1) |
|
|
|
|
MIC/4 |
|
|
|
128 (1) |
8 (1) |
64 (1) |
8 (1) |
16 (1) |
>256 (≥1) |
|
40 | |
|
||||||||||||
AMP | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 |
|
>256 (≥1) |
>256 (≥1) |
|
|
>256 (≥1) |
|
>256 (≥1) |
|
>256 (≥1) |
50 | |
MIC/4 | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
10 | |
|
||||||||||||
CEF | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 |
|
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
10 | |
MIC/4 | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
00 |
MIC of different antibiotics after the association of the extract of
Antibiotic |
Bacterial strains and MIC ( |
|||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Extract concentration | PA124 | AG102 | AG100Atet | EA289 | CM64 | KP55 | KP63 | NEA16 | PS2636 | BM47 | PBS |
|
CHL | 0 | 128 | 8 | 128 | 256 | 256 | 32 | 32 | 16 | 64 | 128 | |
MIC/2 |
|
< |
|
|
|
|
|
< |
|
|
|
|
MIC/4 |
|
< |
|
256 (1) |
|
|
|
|
64 (1) |
128 (1) |
|
|
|
||||||||||||
CIP | 0 | 64 | 4 | >64 | >64 | >64 | 2 | <0.5 | 4 | 8 | <0.5 | |
MIC/2 |
|
< |
|
>64 (≥1) |
|
< |
<0.5 (≥1) |
< |
< |
<0.5 (≥1) |
|
|
MIC/4 |
|
< |
>64 (≥1) |
>64 (≥1) |
|
< |
<0.5 (≥1) |
4 (1) |
|
<0.5 (≥1) |
|
|
|
||||||||||||
TET | 0 | 16 | 16 | 32 | 64 | 4 | 32 | 2 | 4 | 2 | 32 | |
MIC/2 | 16 (1) |
< |
|
|
|
32 (1) |
|
< |
< |
|
|
|
MIC/4 | 16 (1) |
< |
|
|
4 (1) |
32 (1) |
2 (1) |
< |
< |
32 (1) |
|
|
|
||||||||||||
ERY | 0 | 128 | 8 | 128 | 256 | 8 | 16 | 4 | 16 | 16 | 16 | |
MIC/2 | 128 (1) |
< |
|
|
< |
16 (1) |
4 (1) |
|
|
< |
|
|
MIC/4 | 128 (1) |
|
|
|
< |
16 (1) |
4 (1) |
|
|
|
|
|
|
||||||||||||
KAN | 0 | 128 | 4 | 8 | 32 | 32 | 32 | <2 | 16 | 16 | 8 | |
MIC/2 |
|
< |
|
|
|
32 (1) |
<2 (≥1) |
< |
16 (1) |
8 (1) |
|
|
MIC/4 |
|
< |
8 (1) |
|
|
32 (1) |
<2 (≥1) |
|
16 (1) |
8 (1) |
|
|
|
||||||||||||
STP | 0 | 256 | >256 | >256 | 128 | 8 | 64 | 8 | 16 | >256 | 64 | |
MIC/2 |
|
|
|
|
|
64 (1) |
< |
< |
|
|
|
|
MIC/4 |
|
|
|
|
8 (1) |
64 (1) |
|
|
|
|
|
|
|
||||||||||||
AMP | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 | >256 (≥1) |
|
|
|
|
>256 (≥1) |
|
|
>256 (≥1) |
|
|
|
MIC/4 | >256 (≥1) |
|
>256 (≥1) |
|
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
20 | |
|
||||||||||||
CEF | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
|
>256 (≥1) |
>256 (≥1) |
|
|
|
|
|
|
MIC/4 | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
00 |
M1IC of different antibiotics after the association of the extract of bark from
Antibiotic |
Bacterial strains and MIC ( |
|||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Extract |
PA124 | AG102 | AG100Atet | EA289 | CM64 | KP55 | KP63 | NEA16 | PS2636 | BM47 | PBS |
|
CHL | 0 | 128 | 8 | 128 | 256 | 256 | 32 | 32 | 16 | 64 | 128 | |
MIC/2 |
|
|
128 (1) |
256 (1) |
256 (1) |
32 (1) |
|
16 (1) |
64 (1) |
|
40 | |
MIC/4 |
|
8 (1) |
128 (1) |
256 (1) |
256 (1) |
32 (1) |
|
16 (1) |
64 (1) |
128 (1) |
20 | |
|
||||||||||||
CIP | 0 | 64 | 8 | >64 | >64 | >64 | 2 | <0.5 | 4 | 8 | <0.5 | |
MIC/2 |
|
|
>64 (≥1) |
>64 (≥1) |
|
< |
<0.5 (≥1) |
4 (1) |
8 (1) |
<0.5 (≥1) |
40 | |
MIC/4 |
|
8 (1) |
>64 (≥1) |
>64 (≥1) |
>64 (≥1) |
< |
<0.5 (≥1) |
4 (1) |
8 (1) |
<0.5 (≥1) |
20 | |
|
||||||||||||
TET | 0 | 16 | 16 | 32 | 64 | 4 | 32 | 2 | 4 | 2 | 32 | |
MIC/2 |
|
< |
64 (2) |
|
< |
|
|
< |
2 (1) |
32 (1) |
|
|
MIC/4 |
|
< |
64 (2) |
|
< |
32 (1) |
2 (1) |
4 (1) |
2 (1) |
32 (1) |
40 | |
|
||||||||||||
ERY | 0 | 128 | 8 | 128 | 256 | 8 | 16 | 4 | 16 | 16 | 16 | |
MIC/2 | 128 (1) |
|
|
|
8 (1) |
|
4 (1) |
16 (1) |
16 (1) |
|
|
|
MIC/4 | 128 (1) |
8 (1) |
128 (1) |
|
8 (1) |
16 (1) |
4 (1) |
16 (1) |
16 (1) |
|
20 | |
|
||||||||||||
KAN | 0 | 128 | 4 | 8 | 32 | 32 | 32 | <2 | 16 | 16 | 8 | |
MIC/2 | 128 (1) |
4 (1) |
|
32 (1) |
|
|
<2 (≥1) |
16 (1) |
|
8 (1) |
40 | |
MIC/4 | 128 (1) |
4 (1) |
8 (1) |
32 (1) |
|
|
<2 (≥1) |
16 (1) |
16 (1) |
8 (1) |
20 | |
|
||||||||||||
STP | 0 | 256 | >256 | >256 | 128 | 8 | 64 | 8 | 16 | >256 | 64 | |
MIC/2 |
|
|
>256 (≥1) |
128 (1) |
|
64 (1) |
|
16 (1) |
|
|
|
|
MIC/4 |
|
>256 (≥1) |
>256 (≥1) |
128 (1) |
8 (1) |
64 (1) |
8 (1) |
16 (1) |
>256 (≥1) |
|
20 | |
|
||||||||||||
AMP | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 |
|
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
|
>256 (≥1) |
|
>256 (≥1) |
30 | |
MIC/4 | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
00 | |
|
||||||||||||
CEF | 0 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | >256 | |
MIC/2 | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
|
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
10 | |
MIC/4 | >256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
>256 (≥1) |
00 |
The leaves of
Our study has limitations. It mainly reports the activity of crude plant extracts and the identification of the active constituents of the plant would be necessary for better understanding of the reported effects. Though this study deals with food plants, the cytotoxicity studies in normal cell lines will be performed to ascertain their safety.
The results of this study can provide some explanations on the traditional use of certain parts of the plants tested herein to combat infections, particularly those caused by enteric bacteria. Evidence of the antibacterial activity of the studied plants, especially edible ones, as well as the ability of some of them to improve the activity of commonly used antibiotics, is an indication that there is a possibility of discovering alternative antibacterials in these plants.
Ampicillin
American type culture collection
Cefepime
Colony forming unit
Chloramphenicol
Ciprofloxacin
Dimethylsulfoxide
Efflux pump inhibitor
Erythromycin
Fractional inhibitory concentration
p-Iodonitrotetrazolium chloride
Kanamycin
Multidrug-resistant
Mueller-Hinton Broth
Minimal inhibitory concentration
Phenylalanine-arginine-ß-naphthylamide
Resistance nodulation-cell division
Streptomycin
Tetracycline.
The authors declare that they have no conflicts of interest.
Joachim K. Dzotam carried out the study; Victor Kuete designed the experiments. Joachim K. Dzotam and Victor Kuete wrote the manuscript; Victor Kuete supervised the work and provided the bacterial strains; all authors read and approved the final manuscript.
The authors acknowledge the Cameroon National Herbarium for identification of plants.