Ramulus Cinnamomi essential oil exerts an anti-inflammatory effect on RAW264.7 cells through N-acylethanolamine acid amidase inhibition

ETHNOPHARMACOLOGICAL RELEVANCE

Ramulus Cinnamomi, the dried twig of Cinnamomum cassia (L.) J.Presl., is a traditional Chinese medicine (TCM) with anti-inflammatory effects. The medicinal functions of Ramulus Cinnamomi essential oil (RCEO) have been confirmed, although the potential mechanisms by which RCEO exerts its anti-inflammatory effects have not been fully elucidated.

AIM OF THE STUDY

To investigate whether N-acylethanolamine acid amidase (NAAA) mediates the anti-inflammatory effects of RCEO.

MATERIALS AND METHODS

RCEO was extracted by steam distillation of Ramulus Cinnamomi, and NAAA activity was detected using HEK293 cells overexpressing NAAA. N-Palmitoylethanolamide (PEA) and N-oleoylethanolamide (OEA), both of which are NAAA endogenous substrates, were detected by liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). The anti-inflammatory effects of RCEO were analyzed in lipopolysaccharide (LPS)-stimulated RAW264.7 cells, and the cell viability was measured with a Cell Counting Kit-8 (CCK-8) kit. The nitric oxide (NO) in the cell supernatant was measured using the Griess method. The level of tumor necrosis factor-α (TNF-α) in the RAW264.7 cell supernatant was determined using an enzyme-linked immunosorbent assay (ELISA) kit. The chemical composition of RCEO was assessed by gas chromatography-mass spectroscopy (GC-MS). The molecular docking study for (E)-cinnamaldehyde and NAAA was performed by using Discovery Studio 2019 software (DS2019).

RESULTS

We established a cell model for evaluating NAAA activity, and we found that RCEO inhibited the NAAA activity with an IC50 of 5.64 ± 0.62 μg/mL. RCEO significantly elevated PEA and OEA levels in NAAA-overexpressing HEK293 cells, suggesting that RCEO might prevent the degradation of cellular PEA and OEA by inhibiting the NAAA activity in NAAA-overexpressing HEK293 cells. In addition, RCEO also decreased NO and TNF-α cytokines in lipopolysaccharide (LPS)-stimulated macrophages. Interestingly, the GC-MS assay revealed that more than 93 components were identified in RCEO, of which (E)-cinnamaldehyde accounted for 64.88%. Further experiments showed that (E)-cinnamaldehyde and O-methoxycinnamaldehyde inhibited NAAA activity with an IC50 of 3.21 ± 0.03 and 9.62 ± 0.30 μg/mL, respectively, which may represent key components of RCEO that inhibit NAAA activity. Meanwhile, docking assays revealed that (E)-cinnamaldehyde occupies the catalytic cavity of NAAA and engages in a hydrogen bond interaction with the TRP181 and hydrophobic-related interactions with LEU152 of human NAAA.

CONCLUSIONS

RCEO showed anti-inflammatory effects by inhibiting NAAA activity and elevating cellular PEA and OEA levels in NAAA-overexpressing HEK293 cells. (E)-cinnamaldehyde and O-methoxycinnamaldehyde, two components in RCEO, were identified as the main contributors of the anti-inflammatory effects of RCEO by modulating cellular PEA levels through NAAA inhibition.

Ethnobotany, phytochemistry and pharmacology of Arctotis arctotoides (L.f.) O. Hoffm.: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Arctotis arctotoides (Asteraceae) is part of the genus Arctotis. Arctotis is an African genus of approximately 70 species that occur widely in the African continent with diverse medicinal values. This plant is used for the treatment of indigestion and catarrh of the stomach, epilepsy, topical wounds and skin disorders among the ethnic groups in South Africa and reported to have a wide spectrum of pharmacological properties.

AIM OF THE REVIEW

The aim of the present review is to appraise the botany, traditional uses, phytochemistry, pharmacological potential, analytical methods and safety issues of A. arctotoides. Additionally, this review will help to fill the existing gaps in knowledge and highlight further research prospects in the field of phytochemistry and pharmacology.

MATERIALS AND METHODS

Information on A. arctotoides was collected from various resources, including books on African medicinal herbs and Zulu medicinal plants, theses, reports and the internet databases such as SciFinder, Google Scholar, Pubmed, Scopus, Web of Science, and Mendeley by using a combination of various meaningful keywords. This review surveys the available literature of the species from 1962 to April 2017.

RESULTS

In vitro and in vivo studies of the medicinal properties of A. arctotoides were reviewed. The main isolated and identified compounds were reported as sesquiterpenes, farnesol derivatives, germacranolide, guaianolides and some steroids, of which, nine were reported as antimicrobial. Monoterpenoids and sesquiterpenoids were the predominant essential oil compound classes of the leaves, flowers, stems and roots. The present review revealed potential pharmacological properties such as anti-oxidant, antibacterial, antifungal and anticancer activities of plant extracts as well as isolated compounds. Moreover, the review reports the safety profile (toxicity) of the crude extracts that had been screened on brine shrimps, rats and human cell lines.

CONCLUSIONS

The present review has focused on the phytochemistry, botany, ethnopharmacology, biological activities and toxicological information of A. arctotoides. On the basis of reported data, A. arctotoides has emerged as a good source of natural medicine for the treatment of microbial infections, skin diseases, anti-inflammatory and anticancer agents and also provides new insights for further isolation of new bioactive compounds, especially the discovery of antimicrobial, anti-inflammatory and anticancer novel therapeutic lead drug molecules. Additionally, intensive investigations regarding pharmacological properties, safety assessment and efficacy with their mechanism of action could be future research interests before starting clinical trials for medicinal practices.

Current state of knowledge on the traditional uses, phytochemistry, and pharmacology of the genus Hymenaea

ETHNOPHARMACOLOGICAL RELEVANCE

Plants of the genus Hymenaea (Fabaceae) are used in South American and Asian traditional medicines to treat a multitude of disorders, like cough, diarrhea, dysentery, intestinal colic, pulmonary weakness, asthma, anemia, sore throat, and for the treatment of kidney problems, viral related disorders, chronic cystitis, bronchitis, and bladder infections. Some Hymenaea species are also used as vermifuge, and for the treatment of arthritis, and inflammation conditions. This review deals with updated information on the traditional uses, phytochemistry and pharmacology of ethnomedicinally important Hymenaea species in order to provide an input for the future research prospects.

METHODS

Literature available in various recognized databases including Google Scholar, PubMed, SciFinder, Scopus, Springer, Wiley, ACS, Scielo and Web of Science, as well as from theses, dissertations, books, reports, and other relevant websites (www.theplantlist.org), are surveyed, analysed, and included in this review. Herein, the literature related to chemical constituents and pharmacological activities were searched in November 2016.

RESULTS

The literature provided information on ethnopharmacological uses of the South American and African species of the genus Hymenaea (e.g., H. courbaril, H. stigonocarpa, H. onblogifolia, H. martiana, H. parvifolia (South America) and H. verrucosa (African species)) for the treatment of multi-factorial diseases. From these plant species, more than 130 compounds, including fatty acids, flavonoids, terpenoids and steroids, phthalides, phenolic acids, procyanidins and coumarins were identified. Experimental evidences confirmed that the Hymenaea spp. could be used in treating inflammatory disorders, asthma, diarrhea, and some microbial infections. However, reports on the toxicity of Hymenaea species remain scarce.

CONCLUSION

Plants of this genus have offered bioactive samples, both from crude extracts and pure compounds, thus substantiating their effectiveness in traditional medicine. However, intensive investigations of all the species of Hymenaea spp. relating to phytochemical and pharmacological properties, especially their mechanism of action, safety and efficacy could be the future introspection.