Essential oils from Tithonia diversifolia display potent anti-oedematogenic effects and inhibit acid production by cariogenic bacteria

Antibacterial Activity of Essential Oils against Oral Pathogens

This updated review article covers the literature between 2011 and 2021 on the antibacterial activity of EOs against the main bacteria that cause caries and periodontal diseases. The criteria to classify the in vitro antibacterial activity of EOs is updated and the most promising results are addressed.

Confirmation of ethnopharmacological anti-inflammatory properties of Ocotea odorifera and determination of its main active compounds

ETHNOPHARMACOLOGICAL RELEVANCE

Ocotea odorifera (Vell.) Rohwer has been used in traditional medicine in the south of Brazil for the treatment of inflammatory-related conditions, such as rheumatism. However, there is not any scientific evidence for popular use.

AIMS OF THE STUDY

To investigate the O. odorifera anti-inflammatory potential and identification of the main active compounds through metabolomic approaches.

MATERIALS AND METHODS

In order to in vivo evaluate the inhibition of the main inflammatory pathways, the leaf decoction, leaf extract, its fractions and the essential oils from leaves and branches were submitted to the ear oedema and the neutrophils recruitment assays. The samples were chemically investigated by UHPLC-HRMS or GC-MS. The multivariate statistical analysis (PLS-DA) was used to determine the substances correlated with the anti-inflammatory properties.

RESULTS

The in vivo studies indicated a promissory anti-inflammatory effect on both oedema and neutrophil recruitment for some samples including the decoction; hydroethanolic, ethyl acetate, and chloroform fractions; and the essential oils. According to the PLS-DA, the S-(+)-reticuline was evidenced as one of the three compounds of the plant most correlated with both anti-inflammatory mechanisms. Thus, S-(+)-reticuline was isolated and the anti-inflammatory activity was confirmed. Moreover, for the first time, the dual inhibition of oedema and neutrophil recruitment was uncovered and reported. Another compound positively correlated with the anti-inflammatory activity is likely to be a new compound since zero hit on the comprehensive mass database were encountered. The compounds found in the essential oils also showed significant anti-inflammatory activity, and thus indeed the plant has different classes of active substances.

CONCLUSIONS

The decoction of O. odorifera and different fractions from its ethanolic extract demonstrated anti-inflammatory activity through dual inhibition of oedema and neutrophil recruitment. Thus, corroborating the popular medicinal use of the decoction of leaves from O. odorifera as an anti-inflammatory medicine. Besides, reticuline, one of the main active compounds, was isolated and proved to display the dual mechanism of action, indicating the O. odorifera as a promising source of active compounds for the treatment of inflammatory conditions.

Tagitinin A from Tithonia diversifolia provides resistance to tomato spotted wilt orthotospovirus by inducing systemic resistance

Tomato spotted wilt orthotospovirus (TSWV) causes devastating losses to agronomic and ornamental crops worldwide. Currently, there is no effective strategy to control this disease. Use of biotic inducers to enhance plant resistance to viruses maybe an effective approach. Our previous study indicated that Tagitinin A (Tag A) has a high curative and protective effect against TSWV. However, the underlying molecular mechanism of Tag A-mediated antiviral activity remains unknown. In this study, Tag A reduced the expression of the NSs, NSm genes was very low in untreated leaves following TSWV infection. In addition, the expression of all TSWV genes in the inoculated and systemic leaves was inhibited in the protective assay, and with an inhibition rate of more than 85% in systemic leaves. Tag A increased phenylalanine ammonia-lyase (PAL) activity in the curative and protective assays. The concentrations of jasmonic acid (JA) and jasmonic acid -isoleucine (JA-Ile) and the expression of its key gene NtCOI1 in Tag A-treated and systemic leaves of treated plants were significantly higher than those of the control plant. Furthermore, Tag A-induced resistance to TSWV could be eliminated by VIGS-mediated silencing of the NtCOI1 gene. These indicated that Tag A acts against TSWV by activating the JA defense signaling pathway.

Chemical Characterization, Antioxidant, Cytotoxic and Microbiological Activities of the Essential Oil of Leaf of Tithonia Diversifolia (Hemsl) A. Gray (Asteraceae)

The present study aimed to evaluate the chemical composition, antioxidant potential, and the cytotoxic and antimicrobial activity of the essential oil of the plant species Tithonia diversifolia (Hemsl) A. Gray. The essential oil obtained was used to identify the chemical compounds present through the techniques of GC-MS and NMR. The antioxidant potential was calculated by the sequestration method of 2,2-diphenyl-1-picrylhydrazyl. For cytotoxic activity, the larval mortality of Artemia salina was evaluated. The main chemical constituents identified are αpinene (9.9%), Limonene (5.40%), (Z)-β-ocimene (4.02%), p-cymen-8-ol (3.0%), Piperitone (11.72%), (E)-nerolidol (3.78%) and Spathulenol (10.8%). In the evaluation of the antimicrobial activity, bacterial strains of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were used. The results showed that the bacterium E. coli were more susceptible to the presence of the essential oil, presenting minimal inhibitory concentration at the concentrations that were exposed. The essential oil presented antioxidant activity of 54.6% at the concentration of 5 mg·mL^-1 and provided a CI₅₀ of 4.30. It was observed that the essential oil of this species was highly toxic against A. salina lavas, as its cytotoxic activity showed an LC₅₀ of 3.11. Thus, it is concluded that T. diversifolia oils are effective in inhibiting bacterial growth and reducing oxidative stress.