Antibacterial, Antibiofilm, and Antioxidant Activity of Polysaccharides Obtained from Fresh Sarcotesta of Ginkgo biloba: Bioactive Polysaccharide that Can Be Exploited as a Novel Biocontrol Agent

Pharmacological Potential Effects of Algerian Propolis Against Oxidative Stress, Multidrug-Resistant Pathogens Biofilm and Quorum-Sensing

Objectives

This study sought to examine the chemical profile, antioxidant, antimicrobial, antibiofilm, and anti-quorum sensing potential of two propolis ethanolic extracts (PEEs) collected from northeast Algeria.

Materials and Methods

To achieve the main objectives of this study, multiple in vitro tests were employed. The phenolic and flavonoid contents were analyzed, and the chemical composition of both PEE was determined by high-performance liquid chromatography. The antioxidant properties of the propolis extracts were investigated using six complementary tests. The inhibitory effects of propolis extracts were evaluated against multidrug-resistant (MDR) clinical isolates using agar well diffusion and microdilution methods, whereas their antibiofilm and quorum-sensing disruption effects were determined by spectrophotometric microplate methods.

Results

The results demonstrated that phenolic and flavonoid contents were higher in propolis from the Guelma (PEEG) region (PEEG; 188.50 ± 0.33 μg GAE/mg E, 144.23 ± 1.03 μg QE/mg E), respectively. Interestingly, different components were identified, and cynarin was the major compound detected. The PEEG sample exhibited potential antioxidant effects in scavenging ABTS•+ radicals with minimal inhibitory concentration values equal to 10.46 ± 1.40 µg/mL. Furthermore, the highest antibacterial activity was recorded by PEEG against Gram-positive Staphylococcus aureus MDR1. Similarly, PEEG effectively inhibited the biofilm formation of S. aureus MDR1 and the degradation of biofilm was up to 60%. In addition, quorum sensing disruption revealed that both extracts have a moderate capacity for violacein inhibition by the Chromobacterium violaceum ATCC 12472 strain in a concentration-dependent manner.

Conclusion

These findings indicate that propolis can be regarded as a natural therapeutic agent for health problems associated with MDR bacteria and oxidative stress.

Control the carcinogenic bacteria with new polysaccharides from agricultural wastes

Agriculture activities industries produce a huge amount of waste every year. Agricultural wastes are a great source of natural polysaccharides characterized by accessibility, biocompatibility, and ease of modification. Finding new safe antibacterial agents has become one of the top priorities of health organizations worldwide. This priority emerged from the antibiotic resistance pathogenic bacteria hazard. Carcinogenic bacteria are one of the most dangerous antibiotic-resistant pathogenic bacteria. This study tries to investigate the antibacterial activity of polysaccharides from some agricultural wastes against carcinogenic bacteria related to gastrointestinal cancers. We determined the antibacterial activity (in terms of minimum inhibitory concentration (MIC)) and the biofilm reduction capacity. We studied the mechanism of the antibacterial activity by determining the effect of the MIC of the extracted polysaccharides on the plasma membrane permeability and the bacterial DNA content. All extracted polysaccharides showed effective antibacterial activity with low MICs ranging from 2 to 20 μg/mL. The barely straw polysaccharides showed the highest MIC (19.844 μg/mL) against Bacteroides fragilis, while the grape bagasse showed the lowest MIC (2.489 μg/mL) against Helicobacter pylori. The extracted polysaccharide showed high antibiofilm activity. Their capacity to reduce the formation of the pathogenic biofilm ranged from 75 to 95%. Regarding the antibacterial mechanism, the extracted polysaccharides showed destructive action on the DNA and the plasma membrane permeability. The bacterial DNA change percent after the treatment with the different polysaccharides ranged from 29% to -58%. The plasma membrane permeability increased by a high percentage, ranging from 92% to 123%. Agricultural waste polysaccharides are a promising antibacterial agent against antibiotic-resistant carcinogenic bacteria.

A Poly-D-Mannose Synthesized by a One-Pot Method Exhibits Anti-Biofilm, Antioxidant, and Anti-Inflammatory Properties In Vitro

In this study, D-mannose was used to synthesize poly-D-mannose using a one-pot method. The molecular weight, degree of branching, monosaccharide composition, total sugar content, and infrared spectrum were determined. In addition, we evaluated the safety and bioactivity of poly-D-mannose including anti-pathogen biofilm, antioxidant, and anti-inflammatory activity. The results showed that poly-D-mannose was a mixture of four components with different molecular weights. The molecular weight of the first three components was larger than 410,000 Da, and that of the fourth was 3884 Da. The branching degree of poly-D-mannose was 0.53. The total sugar content was 97.70%, and the monosaccharide was composed only of mannose. The infrared spectra showed that poly-D-mannose possessed characteristic groups of polysaccharides. Poly-D-mannose showed no cytotoxicity or hemolytic activity at the concentration range from 0.125 mg/mL to 8 mg/mL. In addition, poly-D-mannose had the best inhibition effect on Salmonella typhimurium at the concentration of 2 mg/mL (68.0% ± 3.9%). The inhibition effect on Escherichia coli O157:H7 was not obvious, and the biofilm was reduced by 37.6% ± 2.9% at 2 mg/mL. For Staphylococcus aureus and Bacillus cereus, poly-D-mannose had no effect on biofilms at low concentration; however, 2 mg/mL of poly-D-mannose showed inhibition rates of 33.7% ± 6.4% and 47.5% ± 4%, respectively. Poly-D-mannose showed different scavenging ability on free radicals. It showed the best scavenging effect on DPPH, with the highest scavenging rate of 74.0% ± 2.8%, followed by hydroxyl radicals, with the scavenging rate of 36.5% ± 1.6%; the scavenging rates of superoxide anion radicals and ABTS radicals were the lowest, at only 10.1% ± 2.1% and 16.3% ± 0.9%, respectively. In lipopolysaccharide (LPS)-stimulated macrophages, poly-D-mannose decreased the secretion of nitric oxide (NO) and reactive oxygen species (ROS), and down-regulated the expression of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). Therefore, it can be concluded that poly-D-mannose prepared in this research is safe and has certain biological activity. Meanwhile, it provides a new idea for the development of novel prebiotics for food and feed industries or active ingredients used for pharmaceutical production in the future.

Ultrasound-assisted extraction and analysis of maidenhairtree polysaccharides

The maidenhairtree polysaccharides (MTPs) have important application prospects. So, the extraction, purification, structure, derivatization and biological activities of polysaccharides from leaves, fruits, and testae of maidenhairtree were disscussed. Polysaccharides were extracted by collaborative extraction methods such as ultrasound-assisted extraction and microwave-assisted extraction. The ultrasound-assisted extraction had higher content and higher efficiency. The structural characteristics and structure-activity relationship of maidenhairtree polysaccharides were studied in order to provide theoretical basis and technical support for the further development and utilization of maidenhairtree polysaccharides.

Leaves, seeds and exocarp of Ginkgo biloba L. (Ginkgoaceae): A Comprehensive Review of Traditional Uses, phytochemistry, pharmacology, resource utilization and toxicity

ETHNOPHARMACOLOGICAL RELEVANCE

Ginkgo biloba L. (Ginkgoaceae) is a treasure species with high medicinal value. The Ming Dynasty "Compendium of Materia Medica" and Qing Dynasty "Bencao Fengyuan" in China recorded this herbal medicine can reduce phlegm, clear poison, treat diarrhea and frequent urination, etc. AIM OF THE STUDY: Until now, there is no painstakingly summarized review on leaves, seeds and exocarp of G. biloba simultaneously. This review will systematically summarize and compare current knowledge of G. biloba.

MATERIALS AND METHODS

Ample original publications related to traditional uses, phytochemistry, pharmacology, resource utilization and toxicity of G. biloba leaves, seeds and exocarp till the end of 2021 were searched and collected by using various literature databases, including China National Knowledge Infrastructure, PubMed, Elsevier, Springer, Google Scholar and Web of Science database.

RESULTS

According to classical Chinese herbal books and Chinese Pharmacopoeia, relieving cough, reducing phlegm, clearing poison and relieving diarrhea are the main pharmacological effects of G. biloba. The common chemical ingredients in different parts of G. biloba are flavonoids, terpenoids, phenolic acids, polysaccharides and endotoxin, etc. Among them, flavonoids and terpenoids are the main bioactive compounds in G. biloba leaves. Phenolic acids are the main bioactive compounds in G. biloba exocarp. G. biloba seeds are rich in nutritional ingredients, such as starch, adipose, protein, etc. Modern pharmacological studies showed that the crude extracts or compounds of G. biloba leaves, seeds and exocarp can be used for treating cardiovascular and cerebrovascular diseases, Alzheimer's disease, atherosclerosis, cancer, asthma, non-alcoholic fatty liver, diabetic complications and other diseases. In daily life, G. biloba seeds were usually used as raw material or additives for commodities, healthy food, drinks, even insecticides and antibacterial agents, etc. G. biloba leaves and seeds have been mainly applied for treating cardiovascular and cerebrovascular diseases, cough and asthma in clinical. However, endotoxins and ginkgolic acids have been identified as the dominating toxic ingredients in different parts of G. biloba. Besides, flavonoids and ginkgolides also have been proved to have toxicity recently.

CONCLUSIONS

This review systematically sums up and compares the traditional uses, phytochemistry, pharmacology, resource utilization and toxicity research progress of G. biloba leaves, seeds and exocarp for the first time. It will provide some comprehensive reference data and suggestions for future research on this herbal medicine.