Biological insights and NMR metabolic profiling of different extracts of Spermacoce verticillata (L.) G. Mey

Comparison of Composition, Free-Radical-Scavenging Capacity, and Antibiosis of Fresh and Dry Leave Aqueous Extract from Michelia shiluensis

Numerous plants of medicinal value grow on Hainan Island (China). Given the lack of knowledge on the phytochemical and pharmacological properties of Michelia shiluensis Chun and Y. F. Wu (M. shiluensis), the application of natural antioxidants and antimicrobials in the food industry has attracted increasing interest. This study aimed to compare the chemical composition, free-radical-scavenging capacity, and antibiosis of aqueous extracts of the fresh and dried leaves of M. shiluensis. The aqueous extract of the leaves of M. shiluensis was obtained using steam distillation, and its chemical components were separated and identified via gas chromatography-mass spectrometry (GC-MS). The free-radical-scavenging capacity and antibiosis were determined. Further, 28 and 20 compounds were isolated from the fresh leaf aqueous extract of M. shiluensis (MSFLAE) and dried leaf aqueous extract of M. shiluensis (MSDLAE), respectively. The free-radical-scavenging capacity of MSFLAE and MSDLAE was determined by the 2,2-diphenyl-1 picrylhydrazyl (DPPH) method, which was 43.43% and 38.74%, respectively. The scavenging capacity of MSFLAE and MSDLAE determined by the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonate (ABTS)) method was 46.90% and 25.99%, respectively. The iron ion reduction capacity of MSFLAE and MSDLAE was determined by the ferric-reducing antioxidant power (FRAP) method as 94.7 and 62.9 μmol Fe2⁺/L, respectively. This indicated that the two leaf aqueous extracts had a certain free-radical-scavenging capacity, and the capacity of MSFLAE was higher than that of MSDLAE. The antibiosis of the two leaf aqueous extracts on the three foodborne pathogenic bacteria was low, but the antimicrobial effects on Gram-positive bacteria were better than those on Gram-negative bacteria. The antibiosis of MSFLAE on Escherichia coli and Staphylococcus aureus was greater than that of MSDLAE. Finally, MSFLAE and MSDLAE both had certain free-radical-scavenging capacities and antibiosis, confirming that the use of this plant in the research and development of natural antioxidants and antibacterial agents was reasonable. Plant aqueous extracts are an essential source of related phytochemistry and have immense pharmacological potential.

Leaf and Flower Extracts of Six Michelia L.: Polyphenolic Composition, Antioxidant, Antibacterial Activities and in Vitro Inhibition of α-Amylase and α-Glucosidase

Methanolic extracts of the leaf and flower of Michelia L., an evergreen aromatic genus widely used in landscaping, industry and medicine of various countries, were analyzed. The UPLC-ESI-MS/MS analysis led to the identification of 28 polyphenols from six Michelia species that widely distributed and cultivated in southern China, among which quinic acid and chlorogenic acid were the main components. The flower extract of Michelia maudiae had the most abundant polyphenols content, as well as high contents of total phenolic (117.31 ± 7.26 mg GAE/g DW) and total flavonoid (251.60 ± 15.56 mg CE/g DW). Meanwhile, it also showed outstanding performance in three antioxidant indexes of DPPH, ABTS and FRAP. The leaf extracts of Michelia chapensis and Michelia floribunda exhibited excellent inhibition against four pathogenic bacteria. Moreover, certain inhibitory activities were displayed by Michelia macclurei extracts against α-amylase and α-glucosidase This study explored the biological activities of six Michelia species, and provided reference for variety selection with the aim of designing novel phyto-pharmaceuticals.