|Year : 2017 | Volume
| Issue : 1 | Page : 11-14
Poor antimicrobial activity on seven cuban plants
Orlando A. Abreu1, Ileana Sánchez2, Guillermo Barreto1, Ana C. Campal2
1 Food Science Department, Faculty of Chemistry, University of Camagüey “Ignacio Agramonte Loynaz”, Camagüey, Cuba
2 Genetic Engineering and Biotechnology Center, Camagüey, Cuba
|Date of Web Publication||21-Apr-2017|
Orlando A. Abreu
Food Science Department, Faculty of Chemistry, University of Camagüey “Ignacio Agramonte Loynaz”, Circunvalación Norte km 5½, Camagüey
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Plant Kingdom still constitutes a source for antimicrobials, screening bioassays of plants extracts is one of the first steps in the search of new antimicrobial compounds. Cuba has a rich flora with a high degree of endemism that practically has not been investigated. Method: Twelve acetone extracts (1mg/ml) of seven Cuban plants (four endemic), were tested by agar disc diffusion method against selected strains of bacteria and fungi: Escherichia coli (three strains), Staphylococcus aureus and Candida albicans. Results: In general null or poor antimicrobial effect was observed, except in Caesalpinia bahamensis subs bahamensis heartwood, that showed activity of interest against bacteria even at 0,5mg/ml; while modest antibacterial effects was found in endemics: Hypericum styphelioides (leave, stem), H. limosum (leave, stem), Vaccinium leonis (leave) and V. ramonii (leave, stem); Agdestis clematidea show lowest effect. S. aureus was the most sensitive bacteria (six species and 11 extracts) and only a negligible activity was found against C. albicans in four extract of four species. Discussion: Morphology of Gram positive bacteria, in contrast to Gram negative that have a more resistant outer membrane, seem to be the cause of S. aureus sensitiveness. Starting from these results, further current antimicrobial research approach related virulence factors mechanisms interference can be carried out in these plants. Conclusions: In this experimental conditions, except in one specie, null or poor antimicrobial effect was found in tested plants, studies on these plants have to be continues, since in other conditions maybe could be found some bacteriostatic or bactericide activity.
Keywords: Antimicrobial activity, Cuba, medicinal plants, plant extracts
|How to cite this article:|
Abreu OA, Sánchez I, Barreto G, Campal AC. Poor antimicrobial activity on seven cuban plants. J Pharm Negative Results 2017;8:11-4
| Introduction|| |
There is an imperative need to develop novel antimicrobials drugs, phenomenon of antibioresistance have emerge as a consequence of the wide use of antibiotics in modern society in humans and in veterinary medicine and in animal production. An approach to face this challenge is the search of natural products, compounds from Plant Kingdom can lead for good antimicrobials.
Flora is usually screened for antimicrobial activity on diverse bacteria and fungi, but frequently only positive reports are published. Concerning plant selection criteria to antimicrobial research different approaches like at random, ethnobotanic or quimiotaxonomic criteria are usually followed, diverse plant extraction methods and bioassays can also be developed on this field.
Cuba has the greatest number of higher plant in the Caribbean Basin (about 7000 species), with a 51% of endemism. Most of the Cuban Flora has not been investigated pharmacologically or phytochemically.
The objective of this work is to test acetonic extract of seven Cuban plants (four of them endemics) as antimicrobial on bacteria and yeast of human clinical interest; some of the plants were selected to be investigated considering its ethnomedical uses, phytochemistry or biological activity of related species:
Agdestis clematidea Moç. et Sessé (Flor de pedo): in “Amancio Rodríguez” Municipality, Las Tunas Province, Cuba, tuberous roots are used in urinary tract infection and as aphrodisiac.
Caesalpinia bahamensis Lam. subs bahamensis (Brasilete): heartwood is used in urinary infection and kidney complains, diuretic activity has been demonstrated in mouse model., C. sappan is reported to have antimicrobial activity against methycillin resistant Staphylococcus aureus (MRSA).
Dendropemon confertiflorus (Krug and Urban in Urban) Leiva and Arias (Cepa caballero) Hypericum styphelioides A. Rich. (Hierba de verraco): in Pinar del Río Province aerial part is used as diuretic
H. limosum Griseb.
Vaccinium leonis Acuña and Roig
V. ramonii Griseb. different species of this genus (ie. V. macrocarpon, V. myrtillus, V. angustifolium) from Eurasia and North America are use as urinary antiseptic and are reported against several bacterial virulence factors in different bacteria.,
| Materials and Methods|| |
Plants material of seven plants were collected in different provinces of Cuba (listed in [Table 1]), botanical identity of species were authenticated by Prof. Rafael del Risco (Curator of Herbarium “Julián Acuña Galé” of the Universidad Pedagógica “José Martí”, Ciudad de Camagüey).
Crude drug from 12 plant parts [Table 1] were obtained by air-drying, particle size was diminished manually, and plant extract was made by maceration in acetone (1:5, w/v) for 48 h. Acetone extracts were dried at room temperature (29°C), stored at 6°C and, at the time of bioassay dilute in 5% dimethyl sulfoxide (DMSO).
Reference microorganisms tested: Gram positive: Staphylococcus aureus (ATCC 25923); Gram negative: Escherichia More Details coli (ATCC 25922, J96/ATCC 700336, 185; the latter is an uropathogenic clinical isolates); and the yeast: Candida albicans (ATCC 10231).
Antimicrobial effect was performed by disc diffusion method. Sterile discs (6 mm diameter) punched out of Whatman No. 1 filter paper was made to absorb solution of plant extract at 1 mg/mL, discs were overlaid on lawn cultures of microorganism in Mueller Hinton Agar medium (Oxoid), incubated at 37°C and, after 24 h the inhibition zones were measured. As reference following controls were used: sulfametoxazol (50 μg disc) and vancomycin (30 μg disc) for bacteria, and amphotericin B (25 μg disc) for yeast, and 5% DMSO was used as negative control. Three replicates were conducted in each case.
| Results and Discussion|| |
Antimicrobial activity, as value of inhibition diameter, of studied plants extracts are recorded in [Table 2]. Except C. bahamensis subs bahamensis extract, most of plant extracts evaluated have none (40 results) or very poor antimicrobial effect, ranging from seven to eight mm in 19 results.
|Table 2: Antimicrobial activity of acetonic extract of seven Cuban plants|
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C. bahamensis was most active plant, even at 0,5 mg/ml, showing activity on the five tested microorganisms, among them is a strain of E. coli (J96/ATCC 700336) that show no sensitiveness to vancomyncin.
A modest activity on bacteria was found in endemic species H. styphelioides (leave, stem), H. limosum (leave, stem), V. leonis (leave), and V. ramonii (leave, stem), D. confertiflorus only have effect on S. aureus, whereas effect of A. clematidea extracts and V. leonis unripe fruit was totally null. In C. albicans, a negligible activity of 7 mm was found in four plant species, whereas S. aureus was most sensitive microorganism with six active plant species and 11 extracts from 13 plant extracts tested.
These results are consistent to the morphology of S. aureus that as Gram positive bacteria have a simple cell wall susceptible to antimicrobial compounds, in contrast to Gram negative that have a more resistant outer membrane.,,,.
Because of agar diffusion method limitations in plant extract research as Ríos and Recio referred, further antimicrobial studies are needed on these species, because in other conditions some bacteriostatic or bactericide activity maybe could be found, then it is not possible to absolutely stated that there is no possibility to document traditional use of these plants as antimicrobial.
These negative and poor negative results concerning these plants can induce another issue to be explored related to virulence factors mechanisms interference, which is currently a novel approach in investigations related to innovative modes of action against microorganisms, for example Vaccinium macrocarpon Ait. (Cranberry) fruit effect on inhibition of uropathogenic E. coli fimbrial adhesion has been widely studied in vitro and in vivo. Activity of plant compounds on virulence factors, such as fimbriae, haemolysin, quorum sensing, or swarming motility, could be probably a superior mechanisms of action that could avoid antibioresistance rather than conventional antimicrobial effect.
| Conclusion|| |
Except in one specie, poor agar diffusion antimicrobial effect was found in seven tested ketonic Cuban plants extracts, poor activity was mainly found on C. albicans and E. coli strains. Further antimicrobial studies are needed in these species.
The authors are grateful to the late Dr. Armando Urquiola, Director of Botanical Garden of Pinar del Río, and Eddy Martínez, MSc, at the CIMAC, Camagüey, Cuba, for support in plant collection.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]