Antibacterial activity and mechanism of pinoresinol from Cinnamomum Camphora leaves against food-related bacteria

Greener Approach for Synthesis of δ-MnO2 Nanoparticles: Access to Pharmaceutically Important Pyrimidines and their Antimicrobial Activity Studies

A sustainable approach for pharmaceutically important pyrimidine derivatives is achieved by using biogenically produced single-phase δ-MnO2 NPs under external ligand-free conditions. The phytochemicals that comprise the extract of Areca Nut Husk (ANH) have been discovered to serve as reducing agents. The role of phytochemicals is not only to aid in the reduction of Mn(VII) into Mn(IV), but they also have an important role in stabilizing the catalyst. The establishment of δ-MnO2 NPs was confirmed inveterate by FE-SEM, p-XRD, ICP-OES (Mn content = 43.17% w/w), EDX, and with an active Mn content of 43.17% w/w. A series of pyrimidine derivatives were prepared in good yields using a one-pot multicomponent synthesis approach under atmospheric conditions. In addition, hot filtration tests, control experiments, gram-scale synthesis, and mechanistic investigations were demonstrated. Additionally, antimicrobial activity studies of δ-MnO2 NPs and pyrimidine derivatives against the Gram-negative bacteria E. coli, growth curve and minimum inhibitory concentration were studied.

Exploring the Pharmacological Potential of Onosma riedliana: Phenolic Compounds and Their Biological Activities

Onosma riedliana Binzet & Orcan, a traditionally used plant species, has been explored for its therapeutic potential in this study. The work presented here is the first report on the phenolic profile and biological activity of this species. Three extracts of varying polarity were prepared, with the methanolic extract containing the highest phenolic content (97.62 ± 0.20 mgGAE/g). Key phenolic compounds identified included pinoresinol, hesperidin, 4-hydroxybenzoic acid, and p-coumaric acid. The methanolic extract exhibited exceptional antioxidant properties, rivaling Trolox as a positive control, primarily attributed to hesperidin and luteolin. Moreover, the ethyl acetate extract demonstrated remarkable inhibition of cholinesterase and tyrosinase enzymes, while the methanolic extract displayed potent activity against carbohydrate hydrolytic enzymes, α-amylase and α-glucosidase. Again, phenolic compounds were shown to be responsible for the inhibition of cholinesterases and tyrosinase, but not for α-amylase and α-glucosidase. These findings underscore Onosma riedliana's potential for incorporation into diverse pharmaceutical formulations, given its multifaceted bioactivity.

Antibacterial Metabolites Produced by Limonium lopadusanum, an Endemic Plant of Lampedusa Island

Lampedusa, the largest island of the Pelagie archipelago, Sicily, Italy, has proven to be a rich source of plants and shrubs used in folk medicine. These plants, often native to the island, have been very poorly investigated for their phytochemical composition and biological potential to be translated into pharmacological applications. To start achieving this purpose, a specimen of Limonium lopadusanum, a plant native to Lampedusa, was investigated for the first time. This manuscript reports the results of a preliminary biological assay, focused on antimicrobial activity, carried out using the plant organic extracts, and the isolation and chemical and biological characterization of the secondary metabolites obtained. Thus 3-hydroxy-4-methoxybenzoic acid methyl ester (syn: methyl isovanillate, (1), methyl syringate (2), pinoresinol (3), erythrinassinate C (4) and tyrosol palmitate (5) were isolated. Their antimicrobial activity was tested on several strains and compound 4 showed promising antibacterial activity against Enterococcus faecalis. Thus, this metabolite has antibiotic potential against the drug-resistant opportunistic pathogen E. faecalis.

High value valorization of lignin as environmental benign antimicrobial

Lignin is a natural aromatic polymer of p-hydroxyphenylpropanoids with various biological activities. Noticeably, plants have made use of lignin as biocides to defend themselves from pathogen microbial invasions. Thus, the use of isolated lignin as environmentally benign antimicrobial is believed to be a promising high value approach for lignin valorization. On the other hand, as green and sustainable product of plant photosynthesis, lignin should be beneficial to reduce the carbon footprint of antimicrobial industry. There have been many reports that make use of lignin to prepare antimicrobials for different applications. However, lignin is highly heterogeneous polymers different in their monomers, linkages, molecular weight, and functional groups. The structure and property relationship, and the mechanism of action of lignin as antimicrobial remains ambiguous. To show light on these issues, we reviewed the publications on lignin chemistry, antimicrobial activity of lignin models and isolated lignin and associated mechanism of actions, approaches in synthesis of lignin with improved antimicrobial activity, and the applications of lignin as antimicrobial in different fields. Hopefully, this review will help and inspire researchers in the preparation of lignin antimicrobial for their applications.

Future Antimicrobials: Natural and Functionalized Phenolics

With incidence of antimicrobial resistance rising globally, there is a continuous need for development of new antimicrobial molecules. Phenolic compounds having a versatile scaffold that allows for a broad range of chemical additions; they also exhibit potent antimicrobial activities which can be enhanced significantly through functionalization. Synthetic routes such as esterification, phosphorylation, hydroxylation or enzymatic conjugation may increase the antimicrobial activity of compounds and reduce minimal concentrations needed. With potent action mechanisms interfering with bacterial cell wall synthesis, DNA replication or enzyme production, phenolics can target multiple sites in bacteria, leading to a much higher sensitivity of cells towards these natural compounds. The current review summarizes some of the most important knowledge on functionalization of natural phenolic compounds and the effects on their antimicrobial activity.

Rahnella aquatilis JZ-GX1 alleviates iron deficiency chlorosis in Cinnamomum camphora by secreting desferrioxamine and reshaping the soil fungal community

Plant growth-promoting rhizobacteria are important for improving plant iron nutrition, but the interactions among inoculants, host plants and soil microorganisms have not been greatly explored. Rahnella aquatilis JZ-GX1 was applied to treat the increasingly serious iron deficiency chlorosis in Cinnamomum camphora, and the resulting improvement in chlorosis was determined by assessing the contents of chlorophyll, active iron, Fe²⁺ and antioxidant enzymes in leaves, the effects on the soil microbial community and the metabolism in the rhizosphere by high-throughput sequencing techniques and liquid chromatography-mass spectrometry (LC-MS). The results showed that inoculation with JZ-GX1 significantly increased the chlorophyll content of C. camphora, which promoted the redistribution of active iron in roots and leaves, increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), and thus reduced membrane damage in iron-deficient C. camphora caused by reactive oxygen species. According to genome prediction and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis, the JZ-GX1 strain could secrete desferrioxamine (DFO), and the concentration of DFO in C. camphora rhizosphere was 21-fold higher than that in uninoculated soil. The exogenous application of DFO increased the SPAD and Fe²⁺ contents in leaves. In addition, the inoculant affected the fungal community structure and composition in the C. camphora rhizosphere soil and increased the abundances of specific taxa, such as Glomus, Mortierella, Trichoderma, and Penicillium. Therefore, R. aquatilis JZ-GX1 application promoted iron absorption in C. camphora trees by secreting DFO and alleviated iron deficiency chlorosis through interactions with the local fungal community.

Phytotoxicity of Chemical Compounds from Cinnamomum camphora Pruning Waste in Germination and Plant Cultivation

Much previous research has indicated most composts of pruning waste are characterized by potential phytotoxicity, it is highly correlated with the chemical compounds of raw materials. Cinnamomum camphora, a common kind of pruning waste in Southeast Asia and East Asia, is characterized by intense bioactivities due to complex chemical components. This study investigated the potential phytotoxicity of C. camphora pruning waste in light of germination and higher plant growth. C. camphora extracted from leaves completely inhibited seed germination and still showed suppression of root elongation at an extremely low dosage. C. camphora extract also displayed significant inhibition of nutrient absorption in tomato seedlings, including moisture, available nutrients (N, P and K) and key microelements (Fe, Mn, Zn and S). The gene expression of aquaporins and transporters of nitrate and phosphate was significantly up-regulated in roots. This could be regarded as a positive response to C. camphora extract for enhancing nutrient absorption. Moreover, the severe damage to the plasma membrane in roots caused by C. camphora extract might seriously affect nutrient absorption. Camphor is the main component of the C. camphora extract that may induce the phytotoxicity of plasma membrane damage, resulting in the inhibition of nutrient absorption and low biomass accumulation. This study provided a new understanding of the ecotoxicological effects of C. camphora pruning waste, indicating that the harmless disposal of pruning waste requires much attention and exploration in the future.

Three new compounds isolated from the whole plants of Salsola collina pall

One new alkaloid, 6, 7-dimethoxyisoquinoline-N-oxide (1), one new benzofuran derivative, 3,7-dimethyl-6-acetyl-8-benzofuranol (2) and one new lignan, salsolains A (3), along with seven known compounds (4-10), were isolated from the whole plant of Salsola collina Pall. Their structures were elucidated by extensive analysis of spectroscopic data (IR, UV, HR-ESI-MS, 1 D and 2 D NMR), and their absolute configurations were determined by the X-ray crystallography and ECD calculation. The activities of compounds 1-10 against inflammatory cytokines IL-6 and TNF-α levels on LPS-induced RAW 264.7 macrophages were assessed, especially, compound 5 (50 μM) exhibited the most significant anti-inflammatory activity with the secretion levels of IL-6 and TNF-α at 3.87% and 4.03%, respectively.

Use of Copper as a Trigger for the in Vivo Activity of E. coli Laccase CueO: A Simple Tool for Biosynthetic Purposes

Laccases are multi-copper oxidases that catalyze the oxidation of various electron-rich substrates with concomitant reduction of molecular oxygen to water. The multi-copper oxidase/laccase CueO of Escherichia coli is responsible for the oxidation of Cu+ to the less harmful Cu2+ in the periplasm. CueO has a relatively broad substrate spectrum as laccase, and its activity is enhanced by copper excess. The aim of this study was to trigger CueO activity in vivo for the use in biocatalysis. The addition of 5 mM CuSO4 was proven effective in triggering CueO activity at need with minor toxic effects on E. coli cells. Cu-treated E. coli cells were able to convert several phenolic compounds to the corresponding dimers. Finally, the endogenous CueO activity was applied to a four-step cascade, in which coniferyl alcohol was converted to the valuable plant lignan (-)-matairesinol.

An Evidence-Based Research on Botanical Sources for Oral Mucositis Treatment in Traditional Persian Medicine

BACKGROUND

Cancer is one of the most prevalent diseases associated with heavy complications in treatment. Mucotoxic cancer therapies such as head and neck radiotherapy and some of the chemotherapy agents may lead to oral mucositis. In addition to its economic consequences, mucositis also affects patients' quality of life. In Traditional Persian Medicine (TPM) manuscripts, several medicaments have been suggested for the treatment of mucositis.

OBJECTIVE

Considering the public welcome for herbal medicine, the current evidence-based review study is conducted to investigate the herbal remedies which have been proposed for oral mucositis in TPM.

METHODS

At first, a comprehensive survey was done on Qanon fi al-Teb, which is the most important textbook of TPM; then the scientific name of the herbs was authenticated according to the botanical textbooks. At last, data banks including Scopus, Pubmed, Web of science and Science direct were investigated for possible relevant properties of each medicinal plant in the literature.

RESULTS

In total, 30 herbs are introduced in this study. According to the registered documents, 18 herbs are reported to have antioxidant, anti-inflammatory, antimicrobial, anti-nociceptive and wound healing properties of which the therapeutic effect of only a few herbs including Glycyrrhiza glabra, Malva sylvestris, Morus nigra, Punica granatum, and Solanum nigrum were directly evaluated against oral mucositis on the literature.

CONCLUSION

Despite the lack of human studies on mucositis for the other discussed herbs, their related pharmacological properties can be considered for new natural drug discovery supported by medieval and traditional experiments.

New perspectives of purple starthistle (Centaurea calcitrapa) leaf extracts: phytochemical analysis, cytotoxicity and antimicrobial activity

Ethnobotanical and ethnopharmacological studies of many Centaurea species indicated their potential in folk medicine so far. However, investigations of different Centaurea calcitrapa L. extracts in terms of cytotoxicity and antimicrobial activity against phytopathogens are generally scarce. The phenolic profile and broad antimicrobial activity (especially towards bacterial phytopathogens) of methanol (MeOH), 70% ethanol (EtOH), ethyl-acetate (EtOAc), 50% acetone (Me₂CO) and dichloromethane: methanol (DCM: MeOH, 1: 1) extracts of C. calcitrapa leaves and their potential toxicity on MRC-5 cell line were investigated for the first time. A total of 55 phenolic compounds were identified: 30 phenolic acids and their derivatives, 25 flavonoid glycosides and aglycones. This is also the first report of the presence of centaureidin, jaceidin, kaempferide, nepetin, flavonoid glycosides, phenolic acids and their esters in C. calcitrapa extracts. The best results were obtained with EtOAc extract with lowest MIC values expressed in µg/mL ranging from 13 to 25, while methicillin resistant Staphylococcus aureus was the most susceptible strain. The most susceptible phytopathogens were Pseudomonas syringae pv. syringae, Xanthomonas campestris pv. campestris and Agrobacterium tumefaciens. The highest cytotoxicity was recorded for EtOAc and Me₂CO extracts with the lowest relative and absolute IC₅₀ values between 88 and 102 µg/mL, while EtOH extract was the least toxic with predicted relative IC₅₀ value of 1578 µg/mL. Our results indicate that all tested extracts at concentration considered as non-toxic can be one of great importance in combat towards phytopathogenic and human pathogenic strains, as well as natural sources of antimicrobials.

Antibacterial, anti-inflammatory, and anti-osteoclastogenic activities of Colocasia antiquorum var. esculenta: Potential applications in preventing and treating periodontal diseases

This study aimed to investigate the inhibitory effects of Colocasia antiquorum var. esculenta (CA) on Porphyromonas gingivalis (P. gingivalis) growth, inflammation, and osteoclastogenesis. CA was effective in inhibiting the growth of P. gingivalis when applied together with an experimental fluoride varnish. CA also significantly decreased the release of interleukin-6, tumor necrosis factor-α, and nitric oxide from lipopolysaccharide-induced RAW 264.7 cells. No significant differences in viability were noted between the cells treated with CA and the controls. In addition, CA significantly attenuated osteoclast differentiation on bone marrow macrophages. In conclusion, CA inhibited the growth of P. gingivalis and showed anti-inflammatory and anti-osteoclastogenic effects. Therefore, CA may have the potential to act as a novel natural agent for preventing periodontitis.

Optimization and Characterization of Microwave-Assisted Hydro-Distillation Extraction of Essential Oils from Cinnamomum camphora Leaf and Recovery of Polyphenols from Extract Fluid

In this study, the efficiency of microwave-assisted hydro-distillation (MAHD) to extract essential oil from Cinnamomum camphora leaf, and the recovery of polyphenols from extract fluid were investigated. The effects of microwave power, liquid-to-material ratio, and extraction time on the extraction efficiency were studied by a single factor test as well as the response surface methodology (RSM) based on the central composite design method. The optimal extraction conditions were a microwave power of 786.27 W, liquid-to-material ratio of 7.47:1 mL/g, and extraction time of 35.57 min. The yield of essential oil was 3.26 ± 0.05% (w/w), and the recovery of polyphenols was 4.97 ± 0.02 mg gallic acid equivalent/g dry weight under the optimal conditions. Furthermore, the comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS) was used to characterize the essential oils of fresh and fallen leaves, and 159 individual compounds were tentatively identified, accounting for more than 89.68 and 87.88% of the total contents, respectively. The main ingredients include sabinene, l-β-pinene, β-myrcene, α-terpineol, 3-heptanone, and β-thujene, as well as δ-terpineol and 3-heptanone, which were first identified in C. camphora essential oil. In conclusion, the MAHD method could extract essential oil from C. camphora with high efficiency, and the polyphenols could be obtained from the extract fluid at the same time, improving the utilization of C. camphora leaf.

Metabolomics analysis to evaluate the antibacterial activity of the essential oil from the leaves of Cinnamomum camphora (Linn.) Presl

ETHNOPHARMACOLOGY RELEVANCE

Cinnamomum camphora (Linn.) Presl (C. camphora) is one of the oldest herbal medicines used as a traditional medicine, owning a wide range of biological functions including anti-bacterial, anti-oxidative, anti-fungal, anti-inflammatory, insecticidal and repellent activities.

OBJECTIVE

The aim of this study was to investigate the antibacterial activity and mechanism of action of the essential oil (EO) from C. camphora.

MATERIALS AND METHODS

The EO was isolated from the leaves of C. camphora by hydrodistillation, and the chemical compositions of the EO were analyzed by gas chromatography-mass spectrometry (GC-MS). The minimum inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC) values of the EO were estimated by the microbroth dilution method. Growth curve was investigated by turbidimetry. Apoptosis was measured by flow cytometry. Morphological change of bacteria was observed by field emission scanning electron microscopy and transmission electron microscopy. The integrity of cell membrane was evaluated by NanoDrop and BCA Protein Assay Kit. The methicillin-resistant Staphylococcus aureus (MRSA) metabolic profile in the presence of the EO was explored by GC-MS-based metabolomics. Isocitrate dehydrogenase (ICDH), α-ketoglutarate dehydrogenase (α-KGDH), succinic dehydrogenase (SDH) and malic dehydrogenase (MDH) activities were detected by commercial kits.

RESULTS

The main components of the EO from the leaves of C. camphora were identified to be linalool (26.6%), eucalyptol (16.8%), α-terpineol (8.7%), isoborneol (8.1%), β-phellandrene (5.1%), and camphor (5.0%). The EO had good activity against MRSA, Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, Salmonella gallinarum and Escherichia coli. MRSA was selected as the model bacterium to illustrate antibacterial mechanism of action of the EO, and the MIC and MBC values was 0.8 and 1.6 mg/mL, respectively. Apoptosis rate of MRSA increased in a concentration-dependent manner after the addition of EO. The cell morphology was damaged by the EO. There were 74 significantly different metabolites, including 29 upregulated and 45 downregulated metabolites in the result of metabolomics evaluation. Seven pathways were enriched by shared differential metabolites. The EO enhanced the activity of ICDH by 47.35%, while weaken MDH, SDH and α-KGDH by 72.63%, 31.52% and 63.29%, respectively.

CONCLUSIONS

The EO from C. camphora showed anti-MRSA activity via damaging cell membranes and disturbing the amino metabolism.

The re-sequencing of complete chloroplast genome of Cinnamomum camphora (Lauraceae) from Quanzhou, China

Cinnamomum camphora is a precious species for its significance of timber. It is also the main component of the subtropical evergreen broad-leaved forest. We report a chloroplast genome of C. camphora from Quanzhou, China. The complete chloroplast genome is 152,730 bp in length consisting of a pair of inverted repeat (IR) regions of 19,968 bp, a small single-copy (SSC) region of 18,874 bp, and a large single-copy (LSC) region of 93,706 bp, respectively. The chloroplast genome encoded 116 genes, including 79 protein-coding genes, 36 tRNA genes, and eight rRNA genes. This result will provide useful genomic basis for the phylogenetic research of Lauraceae.

Cu/H3BTC MOF as a potential antibacterial therapeutic agent against Staphylococcus aureus and Escherichia coli

The objective of this study was to design a more effective antibacterial agent to overcome the problem of fast-growing bacterial resistance.

Antibacterial activity and mechanism of lactobionic acid against Staphylococcus aureus

Lactobionic acid (LBA) is a newly identified natural polyhydroxy acid that is widely used in the food industry. In this study, the antibacterial effects and underlying mechanism of action of LBA against Staphylococcus aureus were investigated. LBA exhibited significant antibacterial activity against S. aureus with a determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 15 mg/mL and 50 mg/mL, respectively. The Growth curves indicated that LBA directly inhibited the growth of S. aureus. Moreover, LBA induced the leakage of alkaline phosphatase and nucleotides in the culture medium, indicating damage to the integrity of the S. aureus cell wall membrane, which was confirmed by transmission electron microscopy observations. The relative electric conductivity measurements indicated that LBA changed the cell membrane permeability. The preservation effect of LBA was evaluated by quantifying the total number of colonies, total volatile base nitrogen (TVB-N), and thiobarbituric acid reactive substances (TBARS). Overall, these results revealed that LBA exerts its antibacterial activity by breaking down the structure of the bacterial cell wall and membrane, thereby releasing the cellular contents as well as inhibiting protein synthesis, which ultimately lead to cell death. The total number of colonies, the TVB-N value, and the TBARS of cold fresh meat treated with preservatives were significantly lower than those of the control group (P < 0.05). With these antibacterial characteristics, LBA has potential to be used as a safe food additive in the food industry.

Application of a Combined Homogenate and Ultrasonic Cavitation System for the Efficient Extraction of Flavonoids from Cinnamomum camphora Leaves and Evaluation of Their Antioxidant Activity In Vitro

A free-of-dust pollution extraction method combined-homogenate and ultrasonic cavitation system, namely, homogenate-combined ultrasonic cavitation synergistic extraction (HUCSE), was proposed for the efficient extraction of flavonoids from Cinnamomum camphora leaves. Response surface methodology of Box-Behnken design was employed to optimize the HUCSE process, and the optimum operation conditions attained with an extraction yield of 7.95 ± 0.27 mg/g were ethanol concentration 76%, homogenate/ultrasonic time 25 min, solvent-to-solid ratio 22 mL/g, and ultrasonic power 240 W. A second-order kinetic mathematical methodology was performed to depict the behaviors of HUCSE and heat reflux extraction method. The results suggested that the developed HUCSE is an efficient and green method for the extraction of C. camphora flavonoids or other plant natural products, where the obvious higher parameters of extraction capacity at saturation, second-order extraction rate constant, and original extraction rate were obtained when compared to the heat reflux method. The antioxidant activity assays in vitro showed that the C. camphora flavonoids possessed strong antioxidant activity and are promising to be applied as a natural alternative antioxidant.