Synthesis and Cytotoxic Activity of Friedelinyl Esters.

Commonly isolated from plants of Celastraceae family, pentacyclic triterpenoids have a broad spectrum of biological activities, such as antitumor, anti-inflammatory, antinociceptive properties, among others. Structural modifications in these triterpenoids can enhance their biological activity, as well as their selectivity, while improving their physicochemical and pharmacokinetic aspects. In this study, eight novel esters were synthesized: four derivatives of 3α-friedelinol (friedelan-3α-yl p-bromobenzoate (1a); friedelan-3α-yl naproxenate (1b); friedelan-3α-yl pent-4-ynoate (1c); friedelan-3α-yl undec-10-ynoate (1d)) and four derivatives of 3ß-friedelinol (friedelan-3ß-yl p-bromobenzoate (2a); friedelan-3ß-yl naproxenate (2b); friedelan-3ß-yl pent-4-ynoate (2c); friedelan-3ß-yl undec-10-ynoate (2d)). Overall, 3α-friedelinol showed greater reactivity when compared to the ß-epimer. The esters 1b-d and 2b-c were tested for antileukemic activity against THP-1 and K-562 cells but showed low cytotoxicity for both cell lines. The most active against THP-1 cells was friedelan-3ß-yl naproxenate (2b, IC50 = 266±6 µM), and the most active against K-562 cells was friedelan-3α-yl pent-4-ynoate (1c, IC50 = 267±5 µM).

Flavonoids and Triterpenoids Isolated From the Ethyl Acetate Extract of M. quadrangulata Leaves.

The new flavonoid (-)-4'-O-methylepicatechin 5-O-ß-D-glucopyranoside (1), along with four known triterpenes (2-5), a steroid (6), and a flavonoid (7) were isolated from the ethyl acetate extract of Maytenus quadrangulata leaves. The chemical structures of the isolated compounds were determined through analysis of 1D NMR (1H and 13C) spectroscopic data, in addition to 2D NMR and spectrometric (MS) data for compound 1. This is the first report of the isolation of daucosterol (6) and (-)-4'-O-methylepigallocatechin (7) from this species. Compounds 1 and 7 were evaluated against the bacteria Staphylococcus aureus and Klebsiella pneumoniae, but neither exhibited activity even at the highest concentration tested.

Evaluation of Cytotoxicity and Antifungal Activity of Friedelanes from Salacia elliptica Roots.

Plants from Salacia genus are used in traditional medicine for a wide range of diseases. Previous studies reported bioactive pentacyclic triterpenoids from S. elliptica leaves and branches. In this study, the novel pentacyclic triterpenoid 7α,15α-dihydroxyfriedelan-3-one (1) was obtained from the roots of Salacia elliptica, along with seven known compounds: friedelan-3-one (2), friedelan-3ß-ol (3), friedelan-1,3-dione (4), friedelan-3,15-dione (5), 15α-hydroxyfriedelan-3-one (6), 15α,26-dihydroxyfriedelan-3-one (7), and 26-hydroxyfriedelan-3,15-dione (8). Additionally, one steroid, spinasterol (9), was also identified. The chemical structures of all compounds were established through 1 H and 13 C-NMR. Compound 1 was analysed by additional 2D experiments (HMBC, HSQC, COSY, and NOESY) for complete elucidation. Furthermore, the cytotoxicity of compounds 2, 3, 6, 7 and 8 against the A549 lung cancer cells model was evaluated. The flow cytometry analysis revealed a significant cytotoxic activity similar to that exhibited by the triterpenoid lupeol. Additionally, compounds 2, 3, 6, and 7 were tested for in vitro antifungal activity against Candida, Cryptococcus and Sporothrix strains. However, all compounds showed no activity at the tested concentrations.

Virucidal antiviral activity of Maytenus quadrangulata extract against Mayaro virus: Evidence for the presence of catechins.

ETHNOPHARMACOLOGICAL RELEVANCE: Mayaro virus (MAYV) is an arbovirus endemic to the Amazon region, which comprises the states of the North and Midwest region of Brazil and encompasses the largest tropical forest in the world, the Amazon Forest. The confirmation of its potential transmission by Aedes aegypti and recent cases in Brazil, mainly in large centers in the northern region, led to the classification of Mayaro fever as an emerging disease. Traditional medicine is commonly used to treat various diseases, mainly by local riverside populations. Some species of the genus Maytenus, which have similar morphologies, are popularly used to treat infections and inflammations. In this context, our research group has studied and confirmed the antiviral activity of several plant-derived compounds. However, several species of this same genus have not been studied and therefore deserve attention. AIM OF THE STUDY: This study aimed to demonstrate the effects of ethyl acetate extracts of leaves (LAE) and branches (TAE) of Maytenus quadrangulata against MAYV. MATERIALS AND METHODS: Mammalian cells (Vero cells) were used to evaluate the cytotoxicity of the extracts. After cell infection by MAYV and the treatment with the extracts, we evaluated the selectivity index (SI), the virucidal effect, viral adsorption and internalization, and the effect on viral gene expression. The antiviral action was confirmed by quantifying the viral genome using RT-qPCR and by analyzing the effect on virus yield in infected cells. The treatment was performed based on the effective concentration protective for 50% of the infected cells (EC50). RESULTS: The leaves (LAE; EC50 12.0 µg/mL) and branches (TAE; EC50 101.0 µg/mL) extracts showed significative selectivity against the virus, with SI values of 79.21 and 9.91, respectively, which were considered safe. Phytochemical analysis revealed that the antiviral action was associated with the presence of catechins, mainly in LAE. This extract was chosen for the subsequent studies since it reduced the viral cytopathic effect and virus production, even at high viral loads [MOI (multiplicity of infection) 1 and 5]. The effects of LAE resulted in a marked reduction in viral gene expression. The viral title was drastically reduced when LAE was added to the virus before infection or during replication stages, reducing virus production up to 5-log units compared to infected and untreated cells. CONCLUSION: Through kinetic replication, MAYV was not detected in Vero cells treated with LAE throughout the viral cycle. The virucidal effect of LAE inactivates the viral particle and can intercept the virus at the end of the cycle when it gains the extracellular environment. Therefore, LAE is a promising source of antiviral agents.

Laticifer ontogenesis and the chemical constituents of Marsdenia zehntneri (Apocynaceae) latex in a semiarid environment.

MAIN CONCLUSION: Anastomosed laticifers with intrusive growth produce latex containing methyl comate and betulin with economic and ecological value in arid environments. Climatic factors influence laticifer development in the apical meristem and vascular cambium. Latex is a complex emulsion with high medicinal as well as ecological value related to plant survival. Marsdenia zehntneri is a shrubby plant that grows on limestone outcrops in the semiarid regions of Brazil. We sought to characterize the ontogenesis of the laticifers of this species and to relate that process to climatic seasonality and phenology through anatomical, ultrastructural, and micro-morphometric evaluations of the apical meristem and vascular cambium. The histochemistry of the secretory structure was investigated and the chemical composition of the latex was analyzed. Phenological assessments were performed by monitoring phenological events for 1 year. The laticifers network of M. zehntneri permeates the entire primary and secondary body of the plant, providing a wide distribution system of defensive compounds. Its laticifers, of a distinct mixed type (anastomosed, with intrusive growth), are numerous and voluminous in the apical meristem but scarce and minute in the secondary phloem. Latex secretion involves the participation of oleoplasts, polysomes, and dictyosomes. Methyl 2,3-dihydroxy-ursan-23-oate, methyl 3-hydroxy-ursan-23-oate, and betulin are encountered in high proportions in the latex and have ecological and medicinal functions. The development of primary laticifers is related to the resumption of apical meristem activity with increasing day length at the end of the austral winter. The development of secondary laticifers is related to high summer temperatures and rainfall that favor vascular cambium activity. The wide distribution of laticifers, their seasonal pattern of secretion, and their latex composition contribute to the adaptation of M. zehntneri to its natural environment.

Pentacyclic Triterpenoids Isolated from Celastraceae: A Focus in the 13C-NMR Data.

The Celastraceae family comprises about 96 genera and more than 1.350 species, occurring mainly in tropical and subtropical regions of the world. The species of this family stand out as important plant sources of triterpenes, both in terms of abundance and structural diversity. Triterpenoids found in Celastraceae species display mainly lupane, ursane, oleanane, and friedelane skeletons, exhibiting a wide range of biological activities such as antiviral, antimicrobial, analgesic, anti-inflammatory, and cytotoxic against various tumor cell lines. This review aimed to document all triterpenes isolated from different botanical parts of species of the Celastraceae family covering 2001 to 2021. Furthermore, a compilation of their 13C-NMR data was carried out to help characterize compounds in future investigations. A total of 504 pentacyclic triterpenes were compiled and distinguished as 29 aromatic, 50 dimers, 103 friedelanes, 89 lupanes, 102 oleananes, 22 quinonemethides, 88 ursanes and 21 classified as others.

Anti-angiogenic activity and safety of intraocular application of triterpenes.

PURPOSE: Assessment of the anti-angiogenic activity and the safety of ophthalmic use of four pentacyclic triterpenes (friedelin, friedelinol, lupenone, and lupeol). METHODS: Triterpenes cytotoxicity (5-640 µmol L-1) was examined in ARPE-19 cells by sulforhodamine B colorimetric method, and the anti-angiogenic activity (50-1000 µmol L-1) was evaluated in the chorioallantoic membrane model. Full-field electroretinography and histological analysis were performed to evaluate intraocular effects of these four triterpenes (at 100 or 500 µmol L-1) in eyes of Wistar rats, for 15 days. RESULTS: In the cytotoxicity assay, friedelin and friedelinol were not able to drastically reduce cell growth. A dose-dependent response was observed in groups exposed to lupeol or lupenone. During the chorioallantoic membrane assay, friedelinol at 500 µmol L-1 reduced the vascularity in 26%; lupeol and lupenone showed promising anti-angiogenic activity, reducing three parameters: vascularized area (> 30%), number of junctions (> 20%), and vessel length (> 15%). According to the electroretinographic and histologic findings, triterpenes at 100 µmol L-1 or lupenone at 500 µmol L-1 did not induce any transient or permanent disturbance in retinal structure or functioning. CONCLUSIONS: Triterpenes at 100 µmol L-1 or lupenone at 500 µmol L-1 were considered safe for potential ophthalmic use.

Maytenus robusta Reissek, a medicinal plant popularly used to treat digestive diseases, promotes ameliorative effects in colon and liver of mice exposed to dextran sulfate sodium.

ETHNOPHARMACOLOGICAL RELEVANCE: Maytenus robusta Reissek (Celesteraceae), popularly named as cafezinho do mato or coração de bugre, is employed to treat inflammatory digestive diseases in the south of Brazil. However, despite popular usage, the effects of this species on an experimental model of ulcerative colitis are unknown. AIM OF THE STUDY: To evaluate the effects of M. robusta extract (HEMR) on colon and liver from mice with colitis induced by dextran sulfate sodium (DSS). MATERIALS AND METHODS: Firstly, the cytotoxicity of HEMR and its effects on ROS and nitrite production in IEC-6 cells were evaluated. The experimental colitis was established by adding 3% DSS on drinking water of mice and the effects of HEMR (1-100 mg/kg, p.o, once a day by 7 days) in colonic and hepatic tissues were analyzed. RESULTS: The HEMR (1-100 µg/mL) did not alter the cell viability but reduced nitrite production of IEC-6 stimulated by LPS. Moreover, HEMR (100 mg/Kg) attenuates macro and microscopic alterations in the colon from mice exposed to DSS, as evidenced by a reduction of the colon shortening, attenuation of the epithelial erosion, submucosal edema and preservation of the Goblet cells integrity, as well as the restoration of mucin depletion. The treatment with HEMR increased GSH amount, reduced LOOH levels and normalizes CAT activity in the colon. The group treated with HEMR showed increased GST activity, reduced MPO activity and decreased inflammatory cytokines secretion (TNF and IL-6) in the colonic tissue. In the liver, HEMR increased GST activity, decreased the GPx activity and reduced IL-6 levels. Furthermore, the HEMR treatment reduced AST and ALT serum levels in mice exposed to DSS. Finally, the HEMR was able to reduce intestinal transit. CONCLUSIONS: HEMR treatment minimizes inflammation of the colon and maintaining the antioxidant homeostasis. In addition, HEMR may be a potential tool to prevent hepatic injury secondary to ulcerative colitis.

Mucilaginous Secretions in the Xylem and Leaf Apoplast of the Swamp Palm Mauritia flexuosa L.f. (Arecaceae).

Mauritia flexuosa palms inhabit wetland environments in the dry, seasonal Brazilian savanna (Cerrado) and produce mucilaginous secretions in the stem and petiole that have a medicinal value. The present study sought to characterize the chemical natures of those secretions and to describe the anatomical structures involved in their synthesis. Chemical analyzes of the secretions, anatomical, histochemical analyses, and electron microscopy studies were performed on the roots, stipes, petioles, and leaf blades. Stipe and petiole secretions are similar, and rich in cell wall polysaccharides and pectic compounds such as rhamnose, arabinose, xylose, mannose, galactose, and glucose, which are hydrophilic largely due to their hydroxyl and carboxylate groups. Mucilaginous secretions accumulate in the lumens of vessel elements and sclerenchyma fibers of the root, stipe, petiole, and foliar veins; their synthesis involves cell wall loosening and the activities of dictyosomes. The outer faces of the cell walls of the parenchyma tissue in the mesophyll expand to form pockets that rupture and release pectocellulose substances into the intercellular spaces. The presence of mucilage in the xylem, extending from the roots to the leaf veins and continuous with the leaf apoplast, and sub-stomatal chambers suggest a strategy for plant water economy.

New Eugenol Glucoside-based Derivative Shows Fungistatic and Fungicidal Activity against Opportunistic Candida glabrata.

A new series of glucosides modified in their saccharide units were synthesized, evaluated against Candida sp., and compared to prototype 1, an eugenol tetracetyl glucoside previously synthesized and shown to be active against Candida glabrata. Among the new glucosides, benzyl derivative 5 was the most promising, showing fungistatic activity at IC50 18.1 µm against Candida glabrata (threefold higher than fluconazole) and fungicidal activity with a low IC90 value of 36.2 µm. Moreover, the cytotoxic activity of compound 5 (CC50 : 580.9 µm), tested in peripheral blood mononuclear cells, suggests its potential as an agent to treat Candida glabrata infections, with a selectivity index of 32. The new eugenol glucoside 5 may be considered as a novel structural pattern in the development of new anti-Candida drugs.