Advancement in Medicinal Plant Research

Number 2, 2020

24-34
Influence of Lippia thymoides Mart. & Schauer and Lippia origanoides Kunth essential oils on planktonic cell and Streptococcus mutans biofilm growth

Authors: Mateus Cardoso Oliveira, João Pedro Cotrim Maia, Patrícia Baier Krepsky, Angélica Maria Lucchese, Rafael Nóbrega Stipp, Felipe Joia, Marcelo Fabiano Gomes Boriollo and Isabel Celeste Caíres Pereira Gusmão

Abstract

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Biofilms comprise of a complex structure of accumulated microorganisms, especially Streptococcus mutans, and are a major factor in the development of caries. This study aimed to evaluate the in vitro antimicrobial action of Lippia thymoides and Lippia origanoides essential oils against S. mutans UA159 by measuring minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) in biofilms. Cell viability was observed using scanning electron microscopy and confocal laser scanning microscopy. The MIC values were 35 μg/ml for L. thymoides and 40 μg/ml for L. origanoides, suggesting that the oils had antimicrobial effects on S. mutans strains and indicated a bactericidal action. These antimicrobial activity tests showed that S. mutans in the biofilm was significantly eliminated, with results better than the action of 0.2% chlorhexidine. These results confirm the antimicrobial activity of these essential oils and provide a promising means for the effective reduction of S. mutans biofilms.

35-42
Phytochemical analysis of Xylopia aethiopica (Dun), Citrus limon (L.) and Allium sativum (L.) extracts and their effect on selected human pathogens

Authors: Okigbo, R. N., Ezebo, R. O. and Okoli, S. I.

Abstract

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A study was carried out to evaluate the effects of phytochemical properties of plant extracts of Xylopia aethiopica, Citrus limon and Allium sativum on selected human pathogens. Phytochemical analysis of ethanol and chloroform of Xylopia aethiopica, Citrus limon and Allium sativum extracts showed presence of flavonoid, alkaloid, HCN, saponin, tannin and sterol. Quantitative phytochemical analysis of Citrus limon, Xylopia aethiopica and Allium sativum revealed Citrus limon has highest flavonoid (2.635±0.021), sterol (0.160±0.000), terpenoid (0.520±0.000) and anthraquinone (2.760±0.057). Xylopia aethiopica has highest composition of hydrogen cyanide (0.835±0.021) while Allium sativum has highest composition of alkaloid (2.080±0.000), saponin (2.080±0.000) and tannin (1.040±0.000). The three plants; Allium sativum, Citrus limon and Xylopia aethiopica showed a significant difference in their composition of all assayed phytochemicals (P < 0.05). The inhibitory effect of plant extracts against S. aureus, E. coli and Pseudomonas spp in all concentrations had Citrus limon and A. sativum as the highest while Xylopia aethiopica showed the least inhibitory activity against Aspergillus spp and Rhizopus spp. The study proves the effectiveness of the plant extracts in the control of human pathogens.