Rauvolfia grandiflora (apocynaceae) extract interferes with staphylococcal density, enterotoxin production and antimicrobial activity

Indole Alkaloids of Rauvolfia ligustrina and Their Anxiolytic Effects in Adult Zebrafish

Rauvolfia species are well known as producers of bioactive monoterpene indole alkaloids, which exhibit a broad spectrum of biological activities. A new vobasine-sarpagan-type bisindole alkaloid (1: ) along with six known monomeric indoles (2, 3/4, 5: , and 6/7: ) were isolated from the ethanol extract of the roots of Rauvolfia ligustrina. The structure of the new compound was elucidated by interpretation of their spectroscopic data (1D and 2D NMR and HRESIMS) and comparison with published data for analog compounds. The cytotoxicity of the isolated compounds was screened in a zebrafish (Danio rerio) model. The possible GABAergic (diazepam as the positive control) and serotoninergic (fluoxetine as the positive control) mechanisms of action in adult zebrafish were also evaluated. No compounds were cytotoxic. Compound 2: and the epimers 3: /4: and 6: /7: showed a mechanism action by GABAA, while compound 1: showed a mechanism action by a serotonin receptor (anxiolytic activity). Molecular docking studies showed that compounds 2: and 5: have a greater affinity by the GABAA receptor when compared with diazepam, whereas 1: showed the best affinity for the 5HT2AR channel when compared to risperidone.

Genus Rauvolfia: A review of its ethnopharmacology, phytochemistry, quality control/quality assurance, pharmacological activities and clinical evidence

ETHNOPHARMACOLOGICAL RELEVANCE

The plants are from the genus Rauvolfia Plum. ex L. (Apocynaceae), which is represented by 74 species with many synonyms, and distributed worldwide, especially in the Asian, and African continents. Traditionally, some of them are used for the treatment of various disorders related to the central nervous system (CNS), cardiovascular diseases (CVD), and as an antidote due to the presence of monoterpene indole alkaloids (MIAs) such as ajmaline (144), ajmalicine (164) serpentine (182), yohimbine (190) and reserpine (214).

AIM

The present review provides comprehensive summarization and critical analysis of the traditional to modern applications of Rauvolfia species, and the major focus was to include traditional uses, phytochemistry, quality control, pharmacological properties, as well as clinical evidence that may be useful in the drug discovery process.

MATERIALS AND METHODS

Information related to traditional uses, chemical constituents, separation techniques/analytical methods, and pharmacological properties of the genus Rauvolfia were obtained using electronic databases such as Web of Science, Scopus, SciFinder, PubMed, PubChem, ChemSpider, and Google Scholar between the years 1949-2021. The scientific name of the species and its synonyms were checked with the information of The Plant List.

RESULTS

A total of seventeen Rauvolfia species have been traditionally explored for various therapeutic applications, out of which the roots of R. serpentina and R. vomitoria are used most commonly for the treatment of many diseases. About 287 alkaloids, seven terpenoids, nine flavonoids, and four phenolic acids have been reported in different parts of the forty-three species. Quality control (QC)/quality assurance (QA) of extracts/herbal formulations of Rauvolfia species was analyzed by qualitative and quantitative methods based on the major MIAs such as compounds 144, 164, 182, 190, and 214 using HPTLC, HPLC, and HPLC-MS. The various extracts of different plant parts of thirteen Rauvolfia species are explored for their pharmacological properties such as antimicrobial, antioxidant, antiprotozoal, antitrypanosomal, antipsychotic, cardioprotective, cholinesterase inhibitory, and hepatoprotective. Of which, clinical trials of herbal formulations/extracts of R. serpentina and MIAs have been reported for CVD, CNS, antihypertensive therapy, antidiabetic effects, and psoriasis therapy, while the extracts and phytoconstituents of remaining Rauvolfia species are predominantly significant, owning them to be additional attention for further investigation under clinical trials and QC/QA.

CONCLUSION

The present communication has provided a comprehensive, systematic, and critically analyzed vision into the traditional uses, phytochemistry, and modern therapeutic applications of the genus Rauvolfia are validated by scientific evidence. In addition, different plant parts from this genus, especially raw and finished herbal products of the roots of R. serpentina have been demonstrated for the QC/QA.

Plants as Sources of Anti-Inflammatory Agents

Plants represent the main source of molecules for the development of new drugs, which intensifies the interest of transnational industries in searching for substances obtained from plant sources, especially since the vast majority of species have not yet been studied chemically or biologically, particularly concerning anti-inflammatory action. Anti-inflammatory drugs can interfere in the pathophysiological process of inflammation, to minimize tissue damage and provide greater comfort to the patient. Therefore, it is important to note that due to the existence of a large number of species available for research, the successful development of new naturally occurring anti-inflammatory drugs depends mainly on a multidisciplinary effort to find new molecules. Although many review articles have been published in this regard, the majority presented the subject from a limited regional perspective. Thus, the current article presents highlights from the published literature on plants as sources of anti-inflammatory agents.

In Vitro Anti-Toxoplasma gondii and Antimicrobial Activity of Amides Derived from Cinnamic Acid

Most cinnamic acids, their esters, amides, aldehydes, and alcohols present several therapeutic actions through anti-inflammatory, antitumor, and inhibitory activity against a great variety of microorganisms. In this work, eight amines derived from cinnamic acid were synthesized and tested against host cells infected with Toxoplasma gondii and the bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, and three strains of Staphylococcus aureus. Compounds 3 and 4 showed the best result against intracellular T. gondii, presenting antiparasitic activity at low concentrations (0.38 and 0.77 mM). The antibacterial activity of these compounds was also evaluated by the agar microdilution method, and amides 2 and 5 had a minimum inhibitory concentration of 250 µg mL⁻¹ against two strains of S. aureus (ATCC 25923 and bovine strain LSA 88). These also showed synergistic action along with a variety of antibiotics, demonstrating that amines derived from cinnamic acid have potential as pharmacological agents.

A comparative study of McFarland turbidity standards and the Densimat photometer to determine bacterial cell density

McFarland Turbidity Standards and the Densimat photometer were compared for their accuracy to adjust bacterial suspensions. Six bacterial species were tested with both methods. Statistical analyses showed that adjusting bacterial suspensions with the Densimat photometer results in less variation within assays and in a more accurate determination of bacterial inocula.

The olive compound 4-hydroxytyrosol inactivates Staphylococcus aureus bacteria and Staphylococcal Enterotoxin A (SEA)

The foodborne pathogen Staphylococcus aureus produces the virulent staphylococcal enterotoxin A (SEA), a single chain protein which consists of 233 amino acid residues with a molecular weight of 27078 Da. SEA is a superantigen that is reported to contribute to animal (mastitis) and human (emesis, diarrhea, atopic dermatitis, arthritis, and toxic shock) syndromes. Changes in the native structural integrity may inactivate the toxin by preventing molecular interaction with cell membrane receptor sites of their host cells. In the present study, we evaluated the ability of the pure olive compound 4-hydroxytyrosol and a commercial olive powder called Hidrox-12, prepared by freeze-drying olive juice, to inhibit S. aureus bacteria and SEA's biological activity. Dilutions of both test substances inactivated the pathogens. Two independent cell assays (BrdU incorporation into newly synthesized DNA and glycyl-phenylalanyl-aminofluorocoumarin proteolysis) demonstrated that the olive compound 4-hydroxytyrosol also inactivated the biological activity of SEA at concentrations that were not toxic to the spleen cells. However, efforts to determine inhibition of the toxin by Hidrox-12 were not successful because the olive powder was cytotoxic to the spleen cells at concentrations found to be effective against the bacteria. The results suggest that food-compatible and safe antitoxin olive compounds can be used to inactivate both pathogens and toxins produced by the pathogens. Practical Application:  The results of this study suggest that food-compatible and safe antitoxin olive compounds can be used to reduce both pathogens and toxins produced by the pathogens in foods.