Therapeutic Potential of Flavonoids and Tannins in Management of Oral Infectious Diseases-A Review.

Medicinal plants are rich sources of valuable molecules with various profitable biological effects, including antimicrobial activity. The advantages of herbal products are their effectiveness, relative safety based on research or extended traditional use, and accessibility without prescription. Extensive and irrational usage of antibiotics since their discovery in 1928 has led to the increasing expiration of their effectiveness due to antibacterial resistance. Now, medical research is facing a big and challenging mission to find effective and safe antimicrobial therapies to replace inactive drugs. Over the years, one of the research fields that remained the most available is the area of natural products: medicinal plants and their metabolites, which could serve as active substances to fight against microbes or be considered as models in drug design. This review presents selected flavonoids (such as apigenin, quercetin, kaempferol, kurarinone, and morin) and tannins (including oligomeric proanthocyanidins, gallotannins, ellagitannins, catechins, and epigallocatechin gallate), but also medicinal plants rich in these compounds as potential therapeutic agents in oral infectious diseases based on traditional usages such as Agrimonia eupatoria L., Hamamelis virginiana L., Matricaria chamomilla L., Vaccinium myrtillus L., Quercus robur L., Rosa gallica L., Rubus idaeus L., or Potentilla erecta (L.). Some of the presented compounds and extracts are already successfully used to maintain oral health, as the main or additive ingredient of toothpastes or mouthwashes. Others are promising for further research or future applications.

Antimicrobial and Antioxidant Properties of Four Lycopus Taxa and an Interaction Study of Their Major Compounds.

The compositions of leaf infusions of three genotypes of Lycopus europaeus L. with origins in central Europe, namely L. europaeus A (LeuA), L. europaeus B (LeuB), and L. europaeus C (LeuC), and one genotype of L. exaltatus (Lex), were examined by LC-MS-DAD (Liquid Chromatography Mass Spectrometry and Diode Array Detection) analysis. This revealed the presence of thirteen compounds belonging to the groups of phenolic acids and flavonoids, with a predominance of rosmarinic acid (RA) and luteolin-7-O-glucuronide (LGlr). The antimicrobial activity of leaf infusions was tested on the collection strains of Gram-positive and Gram-negative bacteria, and on the clinical Staphylococcus aureus strains. We detected higher activity against Gram-positive bacteria, of which the most susceptible strains were those of Staphylococcus aureus, including methicillin-resistant and poly-resistant strains. Furthermore, we examined the antioxidant activity of leaf infusions using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) methods, and on NIH/3T3 cell lines using dichlorodihydrofluorescein diacetate (DCFH-DA). We also studied the mutual interactions between selected infusions, namely RA and/or LGlr. In the mixtures of leaf infusion and RA or LGlr, we observed slight synergism and a high dose reduction index in most cases. This leads to the beneficial dose reduction at a given antioxidant effect level in mixtures compared to the doses of the parts used alone. Therefore, our study draws attention to further applications of the Lycopus leaves as a valuable alternative source of natural antioxidants and as a promising topical antibacterial agent for medicinal use.