Evaluation of combination effects of ethanolic extract of Ziziphus mucronata Willd. subsp. mucronata Willd. and antibiotics against clinically important bacteria

Combination Strategies of Different Antimicrobials: An Efficient and Alternative Tool for Pathogen Inactivation

Despite the discovery and development of an array of antimicrobial agents, multidrug resistance poses a major threat to public health and progressively increases mortality. Recently, several studies have focused on developing promising solutions to overcome these problems. This has led to the development of effective alternative methods of controlling antibiotic-resistant pathogens. The use of antimicrobial agents in combination can produce synergistic effects if each drug invades a different target or signaling pathway with a different mechanism of action. Therefore, drug combinations can achieve a higher probability and selectivity of therapeutic responses than single drugs. In this systematic review, we discuss the combined effects of different antimicrobial agents, such as plant extracts, essential oils, and nanomaterials. Furthermore, we review their synergistic interactions and antimicrobial activities with the mechanism of action, toxicity, and future directions of different antimicrobial agents in combination. Upon combination at an optimum synergistic ratio, two or more drugs can have a significantly enhanced therapeutic effect at lower concentrations. Hence, using drug combinations could be a new, simple, and effective alternative to solve the problem of antibiotic resistance and reduce susceptibility.

Phytochemical profile and antimicrobial activity of the leaves and stem bark of Symphonia globulifera L.f. and Allophylus abyssinicus (Hochst.) Radlk

Introduction

Symphonia globulifera and Allophylus abyssinicus are used in the management of skin rashes and sores, cough, malaria, digestive diseases, stomach ache, wounds and helminthic infections among others in Uganda, Kenya, Ethiopia, Cameroon. This study aimed at determining the phytochemical profile and antimicrobial activity of these two plants.

Methods

The stem bark and leaves of both plants were collected from Bwindi Impenetrable National Park and air-dried under shade at room temperature. Cold maceration, decoction and infusion with methanol, water and ethyl acetate as solvents were used in phytochemical extraction. Preliminary qualitative screening and thin layer chromatography were used for phytochemical profiling. Antimicrobial activity was analysed by agar well diffusion assay, broth macro-dilution assay and fractional inhibition concentration index (FICI).

Results

The leaves and stem bark of both plants have a diverse set of phytochemical compounds of variable polarity including, tannins, alkaloids, flavonoids, saponins, quinones and anthraquinones among others. Generally, methanol and water extracts of S. globulifera and A. abyssinicus had in-vitro bactericidal activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa but weak fungistatic activity against Candida albicans. Allophylus abyssinicus leaf water and S. globulifera leaf methanol extract combination had a synergistic activity (ΣFICI = 0.37) against S. aureus. Similarly, A. abyssinicus stem bark water extract and A. abyssinicus leaf water extract combination had an additive effect (ΣFICI = 1) against P. aeruginosa.

Conclusion

The leaves and stem bark crude extracts of S. globulifera and A. abyssinicus possess a wide range of bioactive phytochemical compounds but have weak antimicrobial activity against S. aureus, E. coli, P. aeruginosa and C. albicans.

Evaluation of Antibacterial Synergism of Methanolic Extract of Dracocephalum kotschyi and Trachyspermum ammi

BACKGROUND

Chemical preservatives are now used in various foods to increase shelf life and maintain quality instead of its natural extracts with anti-bacterial properties from plants can be used. Hence this research was planned to evaluate and study the synergistic antibacterial effect of the methanolic extracts of Dracocephalum kotschyi (D. kotschyi) and Trachyspermum ammi (T. ammi) against standard pathogenic bacteria like: Pseudomonas aeruginosa (P. aeruginosa), Shigella dysenteriae (S. dysenteriae), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).

METHODS

The methanolic extract of D. kotschyi and T. ammi was prepared by the Soxhlet method. The minimum inhibitory concentration (MIC) of this methanolic extracts were determined by the microdilution method. Thus, by determining the amount of fractional inhibitory concentration index (FICI), the interaction between the methanolic extracts of D. kotschyi and T. ammi on the pathogenic bacteria was determined.

RESULTS

In this study, the MIC of the extracts of D. kotschyi and T. ammi on the pathogen; S. aureus was equal to 6.25 mg/mL and 12.5 mg/mL for S. dysenteriae, E. coli and P. aeruginosa. Hence, the combination of methanolic extracts of these plants shows a synergistic antibacterial effect (FICI < 0.5), on all tested pathogenic microorganisms was proved.

CONCLUSION

Due to the antimicrobial synergistic effect and cost-effective production process of methanolic extracts of D. kotschyi and T. ammi, they are used as natural preservatives and flavouring agents to preserve foods.

Pharmaceutical Advantages of GenoTX-407, A Combination of Extracts from Scutellaria baicalensis Root and Magnolia officinalis Bark

Background: Extracts of Scutellaria baicalensis root (SBR) and Magnolia officinalis barks (MOB) possess significant antioxidant, anti-inflammatory, and antimicrobial properties; however, these also exert adverse effects such as cytotoxicity. To overcome the adverse effects, we formulated a combination of the extracts, named GenoTX-407, with SBR and MOB extracts mixed in 5:1 ratio. The antioxidant, antimicrobial, and anti-inflammatory activities of SBR and MOB extracts and GenoTX-407 were evaluated. Methods: To optimize the extraction conditions of SBR and MOB, different ethanol concentrations and extraction times and treatments of the extracts with different solvents for varying time periods were tested. Anti-inflammatory activity was assessed via NO scavenging assay and analysis of anti-inflammatory activity-related gene expression in RAW 264.7 cells. Agar disk diffusion and microdilution assays were used to determine the antimicrobial activity. Antioxidant activity was evaluated through DPPH assay and analyses of peroxidation and antioxidant-related protein expression in HeLa cells. Results: Extraction with 0% ethanol for 2 h and 1.5% phosphoric acid for 0.5 h yielded maximum SBR extracts. For MOB, 50% ethanol extraction for 2 h followed by further extraction in hexane for 0.5 h yielded the highest extracts. SBR (46.1 ± 0.9 %) and MOB (48.9 ± 1.0 %) extracts effectively inhibited NO production, and dose-dependently reduced the expression of TNF-α, iNOS, NF-κB, COX2, and IL-6. MOB and GenoTX-407 inhibited the growth of Escherichia coli, Staphylococcus aureus, Candida albicans, and Propionibacterium acnes, as evidenced in disk diffusion and microdilution assays. SBR (EC50, 107.7 µg/mL and 38.3 µg/mL), MOB (62.41 µg/mL and 72.45 µg/mL), and GenoTX-407 (7.7 µg/mL and 26.4 µg/mL) exhibited excellent antioxidant potency and could scavenge free radicals of DPPH and lipid peroxidation; additionally, SOD, CAT, HO-1, and Nrf2 expression was increased in HeLa cells. SBR showed more potent antioxidant activity than MOB. Contrastingly, MOB exhibited more potent anti-inflammatory and antimicrobial activities than SBR. Interestingly, GenoTX-407 was the most efficient in all the assays, compared with SBR and MOB. Conclusion: This study demonstrated that GenoTX-407, the combination of SBR and MOB, is a potential drug candidate exerting antioxidant and anti-inflammatory effects via the Nrf2/HO-1 and NF-κB signaling pathways.

Ziziphus mucronata Willd. (Rhamnaceae): it's botany, toxicity, phytochemistry and pharmacological activities

Ziziphus mucronata is an important multi-purpose plant species that has been used in African traditional medicine for ages in the treatment of various devastating human and animal infections. The current paper is aimed at providing an overview of uses, toxicology, pharmacological properties and phytochemistry of Z. mucronata. The information used in the current work was retrieved using various search engines, including Pubmed, Science Direct, Google Scholar, Scielo, SciFinder and Scopus. The key words used included Ziziphus mucronata, secondary metabolites, chemistry, biological activity and pharmacology, anti-inflammatory, antimicrobial, antifungal, antiviral, ethnobotanical survey, medicinal uses, safety, toxicology and other related words. Out of the 46 infections which the plant species is used to treat, the most common uses includes sexually transmitted infections, skin infections, diarrhoea and dysentery, respiratory and chest complaints and gynaecological complaints (citations ≥6). Pharmacologically, the plant species exhibited a potential antimicrobial activity yielding a minimum inhibitory concentration of <1 mg/ml against important pathogens which includes Mycobacterium tuberculosis, Moraxella catarrhalis, Staphylococcus aureus, Escherichia coli, Propionibacterium acnes, Candida albicans, Cryptoccoos neoformans amongst other microorganisms. Furthermore, the extracts and compounds from Z mucronata revealed potent antiviral, antioxidant, anti-inflammatory and other activities in vitro. Phytochemically, cyclo-peptide alkaloids (commonly called mucronines) dominates and in conjunction with triterpenes, flavonoids, phenolic acids and anthocyanins. Besides these compounds, the plant species exhibited the presence of important in minerals. These phytoconstituents may well explain the reported biological activities. Although the extracts revealed no cytotoxic effect to Vero cells, further toxicological characteristics of the plant species still needs to be explored. There is also a need to carry out the comprehensive safety profiles of the plant species, including heavy metal detection. Although the plant species revealed important biological activities, which includes antimicrobial, antiviral, anti-diabetic, anti-inflammatory, anti-oxidant, anti-plasmodial, anthelmintic, and anti-anaemic activity in vitro, further research is needed to explore the in vivo studies, other compounds responsible for such activities and the mechanisms of action thereof. Such activities validates the use of the plant species in traditional medicine. The data on the possible use of the plant species in the treatment of diarrhoea, sexually transmitted infections, skin related and gynaecological complaints are scant and still needs to be explored and validated both in vitro and in vivo. Furthermore, the anticancer and anthelmintic activity of the plant species also needs to be explored.

Nimbolide from Azadirachta indica and its derivatives plus first-generation cephalosporin antibiotics: a novel drug combination for wound-infecting pathogens

We evaluate the in vitro efficacy of nimbolide, desacetylnimbin, and the amide derivatives of nimbolide in combination with first-generation cephalosporin antibiotics against major wound-associated bacterial pathogens.