Screening of Medicinal Plants for Antimicrobial Activity: Pharmacognosy and Microbiological Perspectives (original) (raw)

Efficacy and Mechanism of Traditional Medicinal Plants and Bioactive Compounds against Clinically Important Pathogens

Antibiotics

Traditional medicinal plants have been cultivated to treat various human illnesses and avert numerous infectious diseases. They display an extensive range of beneficial pharmacological and health effects for humans. These plants generally synthesize a diverse range of bioactive compounds which have been established to be potent antimicrobial agents against a wide range of pathogenic organisms. Various research studies have demonstrated the antimicrobial activity of traditional plants scientifically or experimentally measured with reports on pathogenic microorganisms resistant to antimicrobials. The antimicrobial activity of medicinal plants or their bioactive compounds arising from several functional activities may be capable of inhibiting virulence factors as well as targeting microbial cells. Some bioactive compounds derived from traditional plants manifest the ability to reverse antibiotic resistance and improve synergetic action with current antibiotic agents. Therefore, the adva...

Medicinal plants and antimicrobial activity

Journal of ethnopharmacology, 2005

In the present paper, we analyze the past, present and future of medicinal plants, both as potential antimicrobial crude drugs as well as a source for natural compounds that act as new anti-infection agents. In the past few decades, the search for new anti-infection agents has occupied many research groups in the field of ethnopharmacology. When we reviewed the number of articles published on the antimicrobial activity of medicinal plants in PubMed during the period between 1966 and 1994, we found 115; however, in the following decade between 1995 and 2004, this number more than doubled to 307. In the studies themselves one finds a wide range of criteria. Many focus on determining the antimicrobial activity of plant extracts found in folk medicine, essential oils or isolated compounds such as alkaloids, flavonoids, sesquiterpene lactones, diterpenes, triterpenes or naphtoquinones, among others. Some of these compounds were isolated or obtained by bio-guided isolation after previously detecting antimicrobial activity on the part of the plant. A second block of studies focuses on the natural flora of a specific region or country; the third relevant group of papers is made up of specific studies of the activity of a plant or principle against a concrete pathological microorganism. Some general considerations must be established for the study of the antimicrobial activity of plant extracts, essential oils and the compounds isolated from them. Of utmost relevance is the definition of common parameters, such as plant material, techniques employed, growth medium and microorganisms tested.

Monograph: In vitro efficacy of 30 ethnomedicinal plants used by Indian aborigines against 6 multidrug resistant Gram-positive pathogenic bacteria

Asian Pacific Journal of Tropical Disease, 2015

To monitor in vitro antibacterial activities of leaf extracts of 30 common and noncommon plants used by aborigines in Kalahandi district, Odisha, against 6 clinically isolated multidrug resistant (MDR) Gram-positive bacteria of 3 genera, Staphylococcus, Streptococcus, and Enterococcus. Methods: The antibiotic sensitivity patterns of 6 bacterial strains were studied with the diskdiffusion method with 17 antibiotics belonging to 8 classes. Monitored plants have ethnomedicinal use and several are used as traditional medicines. Antibacterial properties were studied with the agar-well diffusion method. Minimum inhibitory concentration and minimum bactericidal concentration values of ethanolic and aqueous extracts of plants were determined by the microbroth-dilution method. Results: Ethanolic plant-extracts had the better antibacterial potencies in comparison to their corresponding aqueous extracts. Plants with most conspicuous antibacterial properties in controlling MDR strains of Gram-positive bacteria were aqueous and ethanolic extracts of plants, Ixora coccinea, Nyctanthes arbor-tristis, Polycythaemia rubra, Pongamia pinnata and Syzygium cumini, Carthamus tinctorius, Cucurbita maxima, Murraya koenigii, Leucas aspera, Plumbago indica and Psidium guajava. Ethanolic extracts of most plants had phytochemicals, alkaloids, glycosides, terpenoids, reducing sugars, saponins, tannins, flavonoids and steroids. Conclusions: These plants could be used further for the isolation of pure compounds to be used as complementary non-microbial antimicrobial medicines.

A comparative study of antibacterial activities of wild and cultivated plants used in ethnoveterinary medicine

African Journal of …, 2011

Farmers generally collect fresh plant materials from the wild for ethnoveterinary uses. They are encouraged to harvest with caution and dry or cultivate important materials in order to protect the biodiversity. These recommendations are not validated scientifically. The microplate method for minimum inhibitory concentration (MIC) determination was used to compare wild with cultivated, and fresh with dry plant materials. The MIC values obtained ranged from 1.25 to 0.01 mg/ml. MIC values ≤0.3 mg/ml were considered as cut off point between effective and none effective inhibition. The multilevel linear models (hierarchical linear models), both unadjusted and adjusted models were employed. The plant (name) was considered as level-2 or higher level, while the actual observation was level-1 or lower level. The crude estimates of the odds ratio indicated that wild is significantly 0.57 times less likely than garden to yield MIC values of more than 0.3 mg/ml (p-value = 0.005). Also, fresh are about 4.195 times more likely than dry to yield MIC scores of more than 0.3 mg/ml (p-value < 0.001). Adjusting for conditions "dry and fresh", microbe and solvent; wild is significantly 0.52 times less likely than garden to yield MIC values of more than 0.3 mg/ml (p-value = 0.003). On the other hand, when adjusting for "wild or garden", type of solvents and type of microbes; fresh is significantly 4.202 times more likely than dry to yield MIC values of more than 0.3 mg/ml (p-value < 0.001). These results partially support farmers claiming that wild plant materials are more potent than the grown ones. On the contrary, the results are in favour of drying plant materials.

Medicinal plants: Role, distribution and future

Journal of Pharmacognosy and Phytochemistry, 2020

Medicinal plants have been used for healthcare since time immemorial. Application of plants to prepare medicine has been realized through hit and trail method, and gradually man became able to fulfill his needs from his surroundings. The use of medicinal plants was started by Japanese for carrying out rituals, food flavoring and treating various diseases. Studies have been carried out globally to verify their potential and some of the findings have given rise to what we call plant-based medicines. Being an important source of medicine, these plants have always been of utmost importance in virtually all cultures of civilizations. Medicinal plants are regarded as rich resources of traditional medicines and not only this but these plants serve as an important source for many modern medicines as well. It is the presence of secondary metabolites which is responsible for their characteristic features. By standardizing the health of active plant-derived compounds, herbal drugs can provide ...

Indigenous Knowledge Affords Antimicrobial Plants for the Management of Infections

International Journal of Tropical Disease & Health, 2021

Aim: The research was carried out to ascertain the antimicrobial effect of the plants Omphalocarpum ahia, Homalium letestui, and Coelocaryon oxycarpum, which are used locally to treat some infectious diseases. Place and Duration of Study: Department of Biomedical Sciences, School of Allied Health Sciences, University of Cape Coast, Cape Coast, Ghana and Department of Herbal Medicine, KNUST, Ghana from June to August 2014. Method: The stem barks of the plants were extracted with 70 % methanol and successively Original Research Article Alake et al.; IJTDH, 42(3): 12-21, 2021; Article no.IJTDH.66029 13 partitioned with petroleum ether, ethyl acetate, methanol to obtain three different fractions. The antimicrobial activities of the extracts and fraction against MRSA, S. typhi, E. coli, S. pneumoniae, P. aeruginosa, E. faecalis, and S. aureus were determined using the disk diffusion method and the minimum inhibition concentration by the serial microplate dilution method with 0.2 mg/ml pi...

Medicinal plants

Baral B., Shrestha Vaidya G., Laxmi Maharjan B., Teixeira da Silva J. A., 2014: Phytochemical and antimicrobial characterization of Rhododendron anthopogon from High Nepalese Himalaya [Fitocheminės ir antimikrobinės Rhododendron anthopogon iš Aukštųjų Nepalo Himalajų savybės]. -Bot. Lith., 20(2): 142-152.