An update review on monoterpene indole alkaloids and biological activities of Tabernaemontana species occurring in Brazil.

ETHNOPHARMACOLOGICAL RELEVANCE: The Tabernaemontana genus belongs to the Apocynaceae family of which 30 species are found in Brazil. Some Tabernaemontana species are used by Brazilian indigenous people and other communities, or are listed in the Yanomami Pharmacopeia. Ethnopharmacological data include use(s) for muscle problems, depressed sternum, back pain, abscess, indigestion, eye irritation, earache, itching, vaginal discharge, as an aid for older people who are slow and forgetful, mosquito and snake bites, infection by the human botfly larvae, calmative, and fever. Obviously, many of these uses are attributed to the alkaloids found in Tabernaemontana species. AIM OF THE REVIEW: The aim is to gather information on Tabernaemontana species occurring in Brazil, as sources of monoterpene indole alkaloids (MIAs). In addition, we aim to collect reported experimental demonstrations of their biological activity, which may provide the foundation for further studies, including phytochemistry, the development of medicinal agents, and validation of phytopreparations. MATERIAL AND METHODS: The Brazilian Flora 2020 database was used as source for Tabernamontana species occurring in Brazil. The literature review on these species was collected from Web of Science, Scopus, PubMed, and Scifinder. The keywords included names and synonyms of Tabernaemontana species found in Brazil, which were validated by the Word Flora Online Plant List. RESULTS: A literature survey covering the time frame from 1960 until June 2023 resulted in 121 MIAs, including 48 not yet reported in the last review published in 2016. Some alkaloid extracts, fractions, and isolated alkaloids present evidenced biological activity, such as anticancer, anti-inflammatory, antinociceptive, antimicrobial, antiparasitic, antiviral, and against snake venoms, among others. Notably, ethnopharmacological based information has been the basis of some reports on Tabernaemontana species. CONCLUSIONS: Our literature survey shows that Tabernaemontana species present bioactive MIAs, such as voacamine and affinisine, demonstrating significant cytotoxicity activity against several tumoral cell lines. Those compounds can be considered promising candidates in the search for new anticancer drugs. However, the Amazonian plant biome is increasingly damaged, which may lead to the extinction of biological diversity. This threat may also affect Tabernaemontana species, which have scarcely been investigated regarding the potential of their phytochemicals for the development of new drugs.

Antimycobacterial and Nitric Oxide Production Inhibitory Activities of Triterpenes and Alkaloids from Psychotria nuda (Cham. & Schltdl.) Wawra.

A phytochemical study of leaves and twigs of Psychotria nuda resulted in 19 compounds, including five indole alkaloids, N,N,N-trimethyltryptamine, lyaloside, strictosamide, strictosidine, and 5α-carboxystrictosidine; two flavonolignans, cinchonain Ia and cinchonain Ib; an iridoid, roseoside; a sugar, lawsofructose; a coumarin, scopoletin; a diterpene, phytol; three triterpenes, pomolic acid, spinosic acid, and rotungenic acid; and five steroids, sitosterol, stigmasterol, campesterol, ß-sitosterol-3-O-ß-d-glucoside, and ß-stigmasterol-3-O-ß-d-glucoside. Some compounds were evaluated for their in vitro activity against Mycobacterium tuberculosis and their ability to inhibit NO production by macrophages stimulated by lipopolysaccharide (LPS). The compounds pomolic acid, spinosic acid, strictosidine, and 5α-carboxystrictosidine displayed antimycobacterial activity with minimum inhibitory concentrations ranging from 7.1 to 19.2 µg/mL. These compounds showed promising inhibitory activity against NO production (IC50 3.22 to 25.5 µg/mL). 5α-carboxystrictosidine did not show cytotoxicity against macrophages RAW264.7 up to a concentration of 100 µg/mL. With the exception of strictosamide, this is the first report of the occurrence of these substances in P. nuda.

In vitro acaricide activity of Ocotea aciphylla (Nees) Mez. (Lauraceae) extracts and identification of the compounds from the active fractions.

The in vitro acaricide activity of hexane, ethyl acetate and ethanol extracts of Ocotea aciphylla leaves was investigated by means of an immersion tests using Rhipicephalus (Boophilus) microplus engorged females and larvae. All extracts were shown effective against the different stages of the parasite, and the ethanol extract (50mg/mL concentration) was the most active (more than 90% efficacy in both assays). The ethanolic extract was fractionated using column chromatography with silica gel as stationary phase to furnish several fractions that were tested against larvae of R. (B.) microplus. Three fractions showed high acaricidal activity (50mg/mL), causing between 84.2% and 100% mortality of the larvae. The anticholinesterase effect of these fractions was determined spectrophotometrically using a microtiter assay. The chemical investigation of the active fractions led to the characterization of terpenoids (cadalene 1 and squalene 2), a phenylpropanoid (dillapiole 3) and a phenolic mixture containing five proanthocyanidins (4-8) and a flavonoid(vitexin-2"-O-rhamnoside 9). Our findings suggest that the O. aciphylla has potent acaricidal activity in vitro against R. (B.) microplus, and that different secondary metabolites are responsible for this effect.

Derris (Lonchocarpus) urucu (Leguminosae) extract modifies the peritrophic matrix structure of Aedes aegypti (Diptera:Culicidae).

Aqueous suspension of ethanol extracts of Derris (Lonchocarpus) urucu (Leguminosae), collected in the state of Amazonas, Brazil, were tested for larvicidal activity against the mosquito Aedes aegypti (Diptera:Culicidae). The aim of this study was to observe the alterations of peritrophic matrix in Ae. aegypti larvae treated with an aqueous suspension of D. urucu extract. Different concentrations of D. urucu root extract were tested against fourth instar larvae. One hundred percent mortality was observed at 150 microg/ml (LC(50) 17.6 microg/ml) 24 h following treatment. In response to D. urucu feeding, larvae excreted a large amount of amorphous feces, while control larvae did not produce feces during the assay period. Ultrastructural studies showed tha larvae fed with 150 microg/ml of D. urucu extract for 4 h have an imperfect peritrophic matrix and extensive damage of the midgut epithelium. Data indicate a protective role for the peritrophic matrix. The structural modification of the peritrophic matrix is intrinsically associated with larval mortality.