Synergistic Role of Plant Extracts and Essential Oils against Multidrug Resistance and Gram-Negative Bacterial Strains Producing Extended-Spectrum β-Lactamases

Polyherbal Antiacne Gel: In Vitro Antibacterial Activity and Efficacy Evaluation Against Cutibacterium acnes

Acne is a common skin condition that affects people of all ages and can lead to significant physical and psychological distress. The first line of action against acne is topical products, though the most effective are topical antibiotics. In such a scenario, the development of effective and safe herbal formulations for the treatment of acne is of great importance. Rubia cordifolia, Aloe barbadensis, and Allium cepa extracts are rich sources of bioactive metabolites and are safe compared with antibiotics, in addition to being cost effective, sustainable, and eco-friendly. Also, their combination has not been studied for treating acne, and their potential benefits need to be investigated. The present study aimed to develop an effective polyherbal gel formulation of R. cordifolia, A. barbadensis, and A. cepa combined extract for treating acne and validate its effect with reference to conventional antibiotics. Plant materials were extracted in water by the reflux method, and phytochemical analysis was done for flavonoid, anthraquinone, and phenolic contents. The combined extract (R. cordifolia, A. barbadensis, and A. cepa extracts) was formulated in gel. The selected polyherbal gel was evaluated for in vitro antibacterial activity using agar well diffusion against Cutibacterium acnes (P. acnes) culture. Phytochemical analysis of the composite extract revealed the rich presence of flavonoids, phenolics, and anthraquinones. The polyherbal gels showed good physicochemical properties; however, FCEG-4 was selected for further studies. It was found to be effective against C. acnes (MTCC 1951) in agar well diffusion, as it showed a similar zone of inhibition as that of standard. Also, during in vivo studies, FCEG-4 showed comparable efficacy with clindamycin gel. It was concluded from the study that composite extracts incorporated in an aqueous-based gel system were effective in topical therapy of mild acne vulgaris, showing similar efficacy to that of clindamycin cream.

Repression of resistance mechanisms of Pseudomonas aeruginosa: implications of the combination of antibiotics and phytoconstituents

Antimicrobial resistance is a prevalent problem witnessed globally and creating an alarming situation for the treatment of infections caused by resistant pathogens. Available armaments such as antibiotics often fail to exhibit the intended action against resistant pathogens, leading to failure in the treatments that are causing mortality. New antibiotics or a new treatment approach is necessary to combat this situation. P. aeruginosa is an opportunistic drug resistant pathogen and is the sixth most common cause of nosocomial infections. P. aeruginosa due to its genome organization and other factors are exhibiting resistance against drugs. Bacterial biofilm formation, low permeability of outer membrane, the production of the beta-lactamase, and the production of several efflux systems limits the antibacterial potential of several classes of antibiotics. Combination of phytoconstituents with antibiotics is a promising strategy to combat multidrug resistant P. aeruginosa. Phytoconstituents such as flavonoids, terpenoids, alkaloids, polypeptides, phenolics, and essential oils are well known antibacterial agents. In this review, the activity of combination of the phytoconstituents and antibiotics, and their corresponding mechanism of action was discussed elaborately. The combination of antibiotics and plant-derived compounds exhibited better efficacy compared to antibiotics alone against the antibiotic resistance P. aeruginosa infections.

Recent trends and challenges to overcome Pseudomonas aeruginosa infections

INTRODUCTION

Pseudomonas aeruginosa (PA) is a Gram-negative bacterium that can cause a wide range of severe infections in immunocompromised patients. The most difficult challenge is due to its ability to rapidly develop multi drug-resistance. New strategies are urgently required to improve the outcome of patients with PA infections. The present patent review highlights the new molecules acting on different targets involved in the antibiotic resistance.

AREA COVERED

This review offers an insight into new potential PA treatment disclosed in patent literature. From a broad search of documents claiming new PA inhibitors, we selected and summarized molecules that showed in vitro and in vivo activity against PA spp. in the period 2020 and 2023. We collected the search results basing on the targets explored.

EXPERT OPINION

This review examined the main patented compounds published in the last three years, with regard to the structural novelty and the identification of innovative targets. The main areas of antibiotic resistance have been explored. The compounds are structurally unrelated to earlier antibiotics, characterized by a medium-high molecular weight and the presence of heterocycle rings. Peptides and antibodies have also been reported as potential alternatives to chemical treatment, hereby expanding the therapeutic possibilities in this field.

Dermaseptin B2 bioactive gene's potential for anticancer and anti-proliferative effect is linked to the regulation of the BAX/BBC3/AKT pathway

Dermaseptin B2 (DrsB2) is an antimicrobial peptide with anticancer and angiostatic properties. We aimed to assess the in vitro inhibitory effect of pDNA/DrsB2 on the growth of breast cancer cells and its impact on the expression of genes involved in the BAX/BBC3/AKT pathway. The nucleic acid sequence of DrsB2 was artificially synthesized and inserted into the pcDNA3.1( +) Mammalian Expression Plasmid. PCR testing and enzyme digesting procedures evaluated the accuracy of cloning. The vectors were introduced into cells using LipofectamineTM2000 transfection reagent. The breast cancer cells were assessed by flow cytometry, MTT assessment, soft agar colony method, and wound healing investigation. The gene's transcription was evaluated using real-time PCR with a significance level of P < 0.05. The recombinant plasmid harboring the pDNA/DrsB2 vector was effectively produced, and the gene sequence showed absolute homogeneity (100% similarity) with the DrsB2 gene. The transfection effectiveness of MCF-7 and MCF-10A cells was 79% and 68%, respectively. The findings are measured using the growth inhibition 50% (GI50) metric, which indicates the concentration of pDNA/DrsB2 that stops 50% of cell growth. The proportions of early apoptosis, late apoptosis, necrosis, and viable MCF-7 cells in the pDNA/DrsB2 group were 40.50%, 2.31%, 1.69%, and 55.50%, respectively. The results showed a 100% increase in gene expression in programmed cell death following treatment with pDNA/DrsB2 (**P < 0.01). To summarize, the results described in this work offer new possibilities for treating cancer by targeting malignancies via pDNA/DrsB2 and activating the BAX/BBC3/AKT signaling pathways.

Potential of Flavonoids as Promising Phytotherapeutic Agents to Combat Multidrug-Resistant Infections

BACKGROUND

Considering the limited number of current effective treatments, Multidrug- Resistant (MDR) illnesses have grown to be a serious concern to public health. It has become necessary to look for new antimicrobial drugs because of the emergence of resistance to numerous kinds of antibiotics. The use of flavonoids is one phytotherapeutic strategy that has been researched as a potential remedy for this issue. Secondary plant compounds called flavonoids have been found to have an antibacterial effect against resistant microorganisms.

OBJECTIVE

This review seeks to give readers a glimpse into contemporary studies on flavonoids' potential to fight MDR infections.

METHODS

A systematic search was conducted on electronic databases (PubMed, Scopus, and Google Scholar) using relevant keywords such as flavonoids, MDR infections, antimicrobial activity, and resistance microbes. Studies that investigated the antimicrobial activity of flavonoids against resistant microbes were included in this review.

RESULTS

Most research found that flavonoids have antibacterial efficacy against resistant microorganisms, and some also showed that they have synergistic benefits with traditional antibiotics. The flavonoids quercetin, kaempferol, apigenin, and luteolin were the most often investigated ones. According to research, flavonoids affect microbial gene expression, inhibit microbial enzymes, and disrupt the integrity of microbial cell membranes. Additionally, a few studies have noted the flavonoids' low toxicity and safety.

CONCLUSION

For the treatment of infections that are resistant to many drugs, flavonoids constitute a promising class of phytotherapeutic agents. To develop flavonoid-based treatment methods for treating MDR illnesses and assess the potential of flavonoids as adjuvants to conventional antimicrobial drugs, more study is required.

Synergistic Effect of Plant Compounds in Combination with Conventional Antimicrobials against Biofilm of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida spp

Bacterial and fungal biofilm has increased antibiotic resistance and plays an essential role in many persistent diseases. Biofilm-associated chronic infections are difficult to treat and reduce the efficacy of medical devices. This global problem has prompted extensive research to find alternative strategies to fight microbial chronic infections. Plant bioactive metabolites with antibiofilm activity are known to be potential resources to alleviate this problem. The phytochemical screening of some medicinal plants showed different active groups, such as stilbenes, tannins, alkaloids, terpenes, polyphenolics, flavonoids, lignans, quinones, and coumarins. Synergistic effects can be observed in the interaction between plant compounds and conventional drugs. This review analyses and summarises the current knowledge on the synergistic effects of plant metabolites in combination with conventional antimicrobials against biofilms of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The synergism of conventional antimicrobials with plant compounds can modify and inhibit the mechanisms of acquired resistance, reduce undesirable effects, and obtain an appropriate therapeutic effect at lower doses. A deeper knowledge of these combinations and of their possible antibiofilm targets is needed to develop next-generation novel antimicrobials and/or improve current antimicrobials to fight drug-resistant infections attributed to biofilm.

Medicinal plant Miconia albicans synergizes with ampicillin and ciprofloxacin against multi-drug resistant Acinetobacter baumannii and Staphylococcus aureus

BACKGROUND

Given the rising occurrence of antibiotic resistance due to the existence and ongoing development of resistant bacteria and phenotypes, the identification of new treatments and sources of antimicrobial agents is of utmost urgency. An important strategy for tackling bacterial resistance involves the utilization of drug combinations, and natural products derived from plants hold significant potential as a rich source of bioactive compounds that can act as effective adjuvants. This study, therefore, aimed to assess the antibacterial potential and the chemical composition of Miconia albicans, a Brazilian medicinal plant used to treat various diseases.

METHODS

Ethanolic extracts from leaves and stems of M. albicans were obtained and subsequently partitioned to give the corresponding hexane, chloroform, ethyl acetate, and hydromethanolic phases. All extracts and phases had their chemical constitution investigated by HPLC-DAD-MS/MS and GC-MS and were assessed for their antibiofilm and antimicrobial efficacy against Staphylococcus aureus. Furthermore, their individual effects and synergistic potential in combination with antibiotics were examined against clinical strains of both S. aureus and Acinetobacter baumannii. In addition, 10 isolated compounds were obtained from the leaves phases and used for confirmation of the chemical profiles and for antibacterial assays.

RESULTS

Based on the chemical profile analysis, 32 compounds were successfully or tentatively identified, including gallic and ellagic acid derivatives, flavonol glycosides, triterpenes and pheophorbides. Extracts and phases obtained from the medicinal plant M. albicans demonstrated synergistic effects when combined with the commercial antibiotics ampicillin and ciprofloxacin, against multi-drug resistant bacteria S. aureus and A. baumannii, restoring their antibacterial efficacy. Extracts and phases also exhibited antibiofilm property against S. aureus. Three key compounds commonly found in the samples, namely gallic acid, quercitrin, and corosolic acid, did not exhibit significant antibacterial activity when assessed individually or in combination with antibiotics against clinical bacterial strains.

CONCLUSIONS

Our findings reveal that M. albicans exhibits remarkable adjuvant potential for enhancing the effectiveness of antimicrobial drugs against resistant bacteria.

Hop Flower Supercritical Carbon Dioxide Extracts Coupled with Carriers with Solubilizing Properties-Antioxidant Activity and Neuroprotective Potential

Lupuli flos shows many biological activities like antioxidant potential, extended by a targeted effect on selected enzymes, the expression of which is characteristic for neurodegenerative changes within the nervous system. Lupuli flos extracts (LFE) were prepared by supercritical carbon dioxide (scCO2) extraction with various pressure and temperature parameters. The antioxidant, chelating activity, and inhibition of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and tyrosinase by extracts were studied. The extracts containing ethanol were used as references. The most beneficial neuroprotective effects were shown by the extract obtained under 5000 PSI and 50 °C. The neuroprotective effect of active compounds is limited by poor solubility; therefore, carriers with solubilizing properties were used for scCO2 extracts, combined with post-scCO2 ethanol extract. Hydroxypropyl-β-cyclodextrin (HP-β-CD) in combination with magnesium aluminometasilicate (Neusilin US2) in the ratio 1:0.5 improved dissolution profiles to the greatest extent, while the apparent permeability coefficients of these compounds determined using the parallel artificial membrane permeability assay in the gastrointestinal (PAMPA GIT) model were increased the most by only HP-β-CD.

Evaluation of the Antibacterial Activity of Gentamicin in Combination with Essential Oils Isolated from Different Cultivars and Morphological Parts of Lavender (Lavandula angustifolia Mill.) against Selected Bacterial Strains

The aim of the study was to investigate the antibacterial effects of essential oils isolated from different cultivars and morphological parts of lavender (Lavandula angustifolia Mill.) in combination with the aminoglycoside antibiotic gentamicin. This in vitro study analyzed the effectiveness of the combinations of gentamicin and lavender essential oils against the following strains: Staphylococcus aureus ATCC 25923, Staphylococcus aureus MRSA and Pseudomonas aeruginosa ATCC 9027. The effect of the combination of lavender oils with gentamicin was tested using the checkerboard method. A synergistic effect against S. aureus strain ATCC 25923 was found when gentamicin was combined with lavender essential oils isolated from flowers and leafy stalks (flowers: 'Blue River' FICI-0.192; 'Ellagance Purple' FICI-0.288; leafy stalks: 'Blue River' FICI-0.192; 'Ellagance Purple' FICI-0.320). A synergistic effect was also observed for the combination of gentamicin with lavender essential oils from flowers against the resistant strain of S. aureus (MRSA) ('Blue River' FICI-0,191; 'Ellagance Purple' FICI-0.263), as well as for the essential oils from leafy stalks ('Blue River' FICI-0.076; 'Ellagance Purple' FICI-0.089). No interaction was observed for the combination of studied essential oils with gentamicin against P. aeruginosa strain ATCC 9027 (FICI = 1.083-1.300).

Assessing the Larvicidal Properties of Endemic Campeche, Mexico Plant Piper cordoncillo var. apazoteanum (Piperaceae) against Aedes aegypti (Diptera: Culicidae) Mosquitoes

The research aims to investigate the mortality effect of essential oil from Piper cordoncillo var. apazoteanum, an endemic plant from Campeche, Mexico, on early second-instar Aedes aegypti larvae; it also aims to identify the volatile compounds present in the fresh leaves of the plant. To test the effectiveness of the essential oil, we followed World Health Organization Standard Procedures. Larvae were observed for 17 consecutive days after treatment to determine the mortality and growth-inhibitory effect exerted by the essential oil. The results showed that the essential oil was effective in controlling mosquito populations. At a concentration of 800 ppm, the oil achieved an effectiveness rate of 70.00 ± 8.16% after 24 h, increasing to 100.00 ± 0.01% mortality after 72 h. With a concentration of 400 ppm, the effectiveness was 98.33 ± 0.17% by the end of the experiment. Furthermore, the obtained results demonstrated that the LC₅₀ value was 61.84 ± 6.79 ppm, while the LC₉₀ value was 167.20 ± 11.49 ppm. Essential oil concentrations inhibited the growth of immature insect stages, with concentrations between 800-100 ppm demonstrating very high inhibitory activity, and the lowest concentration of 50 ppm showing high inhibitory activity. The study also identified 24 chemical compounds representing 86.71% of the volatile compound composition of the fresh leaves of P. cordoncillo; the most abundant compounds were Safrole, Caryophyllene oxide, E-Nerolidol, and Calarene epoxide. The method used to extract the volatile compounds, solvent-free microwave extraction (SFME), is a promising alternative to traditional methods that avoids the use of potentially harmful solvents, making it more ecologically friendly and potentially safer for professionals handling the extracted compounds. Overall, the study demonstrates the potential of P. cordoncillo essential oil as an effective means of controlling mosquito populations, and provides valuable information on the chemical composition of the plant.Moreover, our study is the first to report on the biological activity and chemical composition of P. cordoncillo worldwide.

Enzymatic Activity and Horizontal Gene Transfer of Heavy Metals and Antibiotic Resistant Proteus vulgaris from Hospital Wastewater: An Insight

Globally, the issue of microbial resistance to medicines and heavy metals is getting worse. There are few reports or data available for Proteus vulgaris (P. vulgaris), particularly in India. This investigation intends to reveal the bacteria's ability to transmit genes and their level of resistance as well. The wastewater samples were taken from several hospitals in Lucknow City, India, and examined for the presence of Gram-negative bacteria that were resistant to antibiotics and heavy metals. The microbial population count in different hospital wastewaters decreases with increasing concentrations of metal and antibiotics. Among all the examined metals, Ni and Zn had the highest viable counts, whereas Hg, Cd, and Co had the lowest viable counts. Penicillin, ampicillin, and amoxicillin, among the antibiotics, demonstrated higher viable counts, whereas tetracycline and erythromycin exhibited lower viable counts. The MIC values for the P. vulgaris isolates tested ranged from 50 to 16,00 μg/ml for each metal tested. The multiple metal resistance (MMR) index, which ranged from 0.04 to 0.50, showed diverse heavy metal resistance patterns in all P. vulgaris isolates (in the case of 2-7 metals in various combinations). All of the tested isolates had methicillin resistance, whereas the least number of isolates had ofloxacin, gentamycin, or neomycin resistance. The P. vulgaris isolates displayed multidrug resistance patterns (2-12 drugs) in various antibiotic combinations. The MAR indexes were shown to be between (0.02-0.7). From the total isolates, 98%, 84%, and 80% had urease, gelatinase, and amylase activity, whereas 68% and 56% displayed protease and beta-lactamase activity. Plasmids were present in all the selected resistant isolates and varied in size from 42.5 to 57.0 kb and molecular weight from 27.2 to 37.0 MD. The transmission of the antibiotic/metal resistance genes was evaluated between a total of 7 pairs of isolates. A higher transfer frequency (4.4 × 10-1) was observed among antibiotics, although a lower transfer frequency (1.0 × 10-2) was observed against metals in both the media from the entire site tested. According to exponential decay, the population of hospital wastewater declined in the following order across all sites: Site II > Site IV > Site III > Site I for antibiotics and site IV > site II > site I >site III for metal. Different metal and antibiotic concentrations have varying effects on the population. The metal-tolerant P. vulgaris from hospital wastewater was studied in the current study had multiple distinct patterns of antibiotic resistance. It could provide cutting-edge methods for treating infectious diseases, which are essential for managing and assessing the risks associated with hospital wastewater, especially in the case of P. vulgaris.

Antibacterial effect of Rubus chingii flower extract against multidrug-resistant bacteria

Rubus chingii is a well reputed member of Chinese traditional medicine system and is used for managing different ailments since historic times. The present report elucidates the growth impeding effect of R. chingii flower extract against multidrug resistant Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. The extracts were prepared using standard Soxhlet extraction method using ethanol, methanol and acetone as a solvent. The extracts were further subjected to agar streak method and the stains that showed their sensitivity were further evaluated for minimum inhibitor concentration (MIC) assessment through TCC method. Subsequently the MIC was further used for well diffusion assay. All the strains used in the study showed their sensitivity towards R. chingii flowers extract in respective solvents. Highest antibacterial activity was seen against E. coli. and S. aureus whereas the lowest activity was recorded against K. pneumoniae. Thus the study reported herewith provided an insight into the antibacterial efficacy of R. chingii flower extract against MDR E. coli., S. aureus and K. pneumoniae.