Extracts and fractions of Croton L. (Euphorbiaceae) species with antimicrobial activity and antioxidant potential

Essential Oils of Aromatic Plant Species from the Atlantic Rainforest Exhibit Extensive Chemical Diversity and Antimicrobial Activity

Microbial resistance, caused by the overuse or inadequate application of antibiotics, is a worldwide crisis, increasing the risk of treatment failure and healthcare costs. Plant essential oils (EOs) consist of hydrophobic metabolites with antimicrobial activity. The antimicrobial potential of the chemical diversity of plants from the Atlantic Rainforest remains scarcely characterized. In the current work, we determined the metabolite profile of the EOs from aromatic plants from nine locations and accessed their antimicrobial and biocidal activity by agar diffusion assays, minimum inhibitory concentration, time-kill and cell-component leakage assays. The pharmacokinetic properties of the EO compounds were investigated by in silico tools. More than a hundred metabolites were identified, mainly consisting of sesqui and monoterpenes. Individual plants and botanical families exhibited extensive chemical variations in their EO composition. Probabilistic models demonstrated that qualitative and quantitative differences contribute to chemical diversity, depending on the botanical family. The EOs exhibited antimicrobial biocidal activity against pathogenic bacteria, fungi and multiple predicted pharmacological targets. Our results demonstrate the antimicrobial potential of EOs from rainforest plants, indicate novel macromolecular targets, and contribute to highlighting the chemical diversity of native species.

Antimicrobial activities and mechanisms of extract and components of herbs in East Asia

Antibacterial drugs face increasing challenges due to drug resistance and adverse reactions, which has created a pressing need for the discovery and development of novel antibacterial drugs. Herbs have played an important role in the treatment of infectious diseases. This review aims to summarize, analyze and evaluate the antibacterial activities and mechanisms of components from popular herbs in East Asia. In this review, we have searched and summarized the scientific papers published during the past twenty-year period from electronic databases such as PubMed, ScienceDirect, and Web of Science. These herbs and their components, including alkaloids, flavonoids, essential oils, terpenes, organic acids, coumarins and lignans, display potential antimicrobial effects. Herbal medicine formulas (HMFs) usually show stronger antibacterial activity than single herbs. Herbs and HMFs bring forth antibacterial activities by damaging cell membranes and walls, inhibiting nucleic acid and protein synthesis, and increasing intracellular osmotic pressure. These herbs and their components can be developed as potential and promising novel antibacterial herbal products.

Inhibitory Effect on Nitric Oxide Release in LPS-Stimulated Macrophages and Free Radical Scavenging Activity of Croton linearis Jacq. Leaves

Oxidative stress is an important component of many diseases including cancer, along with inflammatory and neurodegenerative processes. Natural antioxidants have emerged as promising substances to protect the human body against reactive oxygen and nitrogen species. The present study evaluates the inhibition of nitric oxide (NO) production in LPS-stimulated RAW 264.7 murine macrophages and the free radical scavenging activity of Croton linearis Jacq. leaves. UPLC-QTOF-MS analysis identified 18 compounds: nine alkaloids with a morphinane, benzylisoquinoline or aporphine nucleus, and nine O-glycosylated-flavonoids with quercetin, kaempferol and isorhamnetin as the aglycones. The crude extract (IC₅₀ 21.59 µg/mL) and the n-hexane fraction (IC₅₀ 4.88 µg/mL) significantly reduced the NO production in LPS-stimulated macrophages but with relatively high cytotoxicity (CC₅₀ 75.30 and CC₅₀ 70.12 µg/mL, respectively), while the ethyl acetate fraction also showed good activity (IC₅₀ 40.03 µg/mL) without affecting the RAW 264.7 cell viability. On the other hand, the crude extract, as well as the dichloromethane and ethyl acetate fractions, showed better DPPH and ABTS free radical scavenging activities. Considering the chemical composition and the activity observed for Croton linearis leaves, they may be considered a good source of antioxidants to combat oxidative damage-related diseases.

Chemical composition and antibacterial activity of 12 medicinal plant ethyl acetate extracts using LC-MS feature-based molecular networking

INTRODUCTION

Widespread use of antibiotics has led to an increase in bacterial multiple drug resistance, thereby searching for natural antimicrobial agents from plants becomes an effective and alternative approach. In the present study, we selected six foodborne bacteria to evaluate the antibacterial activities of 12 medicinal plants ethyl acetate (EA) extracts.

OBJECTIVE

This study aims to search for natural antibiotic substitutes from plant extracts. The antibacterial components were further discussed through chemometric and mass spectroscopic analyses.

METHODOLOGY

Agar well diffusion and the microdilution methods were used to test the antibacterial activity. Total phenolic content (TPC) and total flavonoid content (TFC) were used to judge the active phytochemicals. To further characterise the potential antibacterial components, an ultra-performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS) coupled with Pearson correlation and feature-based molecular network (FBMN) were proposed.

RESULTS

Most of the plant extracts possessed antibacterial activity against Bacillus subtilis and Salmonella typhi. Toona sinensis shoots and Firmiana simplex barks showed high inhibitory activities against Staphylococcus aureus, Shigella dysenteriae, and Escherichia coli strains with minimum inhibitory concentrations (MICs) of 1.56, 0.78, and 0.39 mg/mL, respectively. Salmonella typhi was highly sensitive to Firmiana simplex barks with an inhibitory diameter up to 21.67 ± 0.95 mm, and MIC at 0.78 mg/mL. Moreover, Toona sinensis shoots and Firmiana simplex barks had the highest TPCs.

CONCLUSION

Our results indicated that Toona sinensis shoots, Koelreuteria paniculate seeds, and Firmiana simplex barks could be supplied as potential sources of antimicrobial agents. Furthermore, 36 potential bioactive compounds were identified mainly as polyphenols, glycosides, and terpenoids.