New reports on flavonoids, benzoic- and chlorogenic acids as rare features in the Psychotria alliance (Rubiaceae)

Acute exposure of zebrafish (Danio rerio) adults to psychotria carthagenensis leaf extracts: chemical profile, lack of genotoxicity and histological changes

Psychotria carthagenensis is a shrubby plant, often consumed by traditional populations in religious rituals. Previous studies have shown that this plant's infusion can inhibit the activity of Acetylcholinesterase (AChE) in rats. Despite the therapeutic potential, there is a lack of research regarding its possible toxicological and genotoxic effects. Hence, this study aimed to analyze the chemical profile of the ethanol extract from P. carthagenensis leaves by LC-DAD-MS and assess its possible toxicity and genotoxicity in zebrafish (Danio rerio). Adult zebrafish (N = 9/group) were exposed at different concentrations and the LC50 was calculated. Frequencies of micronucleus (MN) and nuclear abnormalities (NA) were estimated for genotoxic effects, and degree of tissue changes (DTC) was used to assess the liver and gill histopathology. From the LC-DAD-MS analyses, the identified compounds included N-fructosyl valine, ethyl hexoside, 5-O-E-caffeoylquinic acid, N-feruloylagmatime, roseoside, di-O-deoxyhexoyl-hexosyl quercetin, loiolide, and oleamide. The calculated values of LC50 did not vary significantly during the time of exposure. At the concentrations of 1.25, 2.5, 3.75, 5, 7.5, 10 and 15 mg/L, there was no genotoxicity, and only low to moderate toxicity for the tissues was observed, despite mortality of 100% at doses of 20-100 mg/L of P. carthagenensis ethanolic leaf extract. There were changes in cytoplasm of hepatocytes at 1.25 mg/L, and karyorrhexis, karyolysis and megalocytosis at 10 mg/L. In the gills, the alterations were primary lamellar hyperplasia in all concentrations, and at 10 mg/L, secondary lamellar edema and vascular hyperemia were common. Additionally, the chemical composition of P. carthagenensis was expanded.

Two Novel Iboga-Type and an Oxindole Glucuronide Alkaloid from Tabernaemontana peduncularis Disclose Related Biosynthetic Pathways to Tabernaemontana divaricata

Phytochemical investigation of the two Tabernaemontana species (Apocynaceae) T. peduncularis Wall. and T. divaricata (L.) R.Br. ex Roem. & Schult. indicated closely related biosynthetic pathways leading to lipophilic and hydrophilic alkaloids. In total, 18 specialized metabolites comprising indole-derived alkaloid aglycones, three oxindole-derived alkaloid glycosides, and two iridoid glucosides could be identified in the studied species. Among the alkaloids, the two Iboga-type alkaloids 3,7-coronaridine isoindolenine, coronaridine 3,4-iminium and a javaniside derivative bearing a glucuronic acid, named javanuronic acid, could be described by spectroscopic and spectrometric methods for the first time. A docking experiment using alpha-fold was performed to generate a protein model of the enzyme 7-deoxyloganetic acid glucosyl transferase. Performed bioassays exhibited a growth reduction of neonate Spodoptera littoralis larvae and reduced cell viability of HepG2 cells of the extracts containing Iboga alkaloids, whilst the javaniside derivatives containing hydrophilic fraction did not show any effects. These findings indicate a high flexibility in the formation of bioactive indole alkaloid aglycones by Tabernaemontana species and also evidence similar accumulation trends in both species as well as indicate that biosynthetic routes leading to oxindole alkaloids like javanisides are more widespread than reported. Furthermore, the incorporation of the three novel compounds into potential biosynthetic pathways is discussed.

Phytochemistry Meets Geochemistry—Blumenol C Sulfate: A New Megastigmane Sulfate from Palicourea luxurians (Rubiaceae: Palicoureeae)

There is a previously neglected influence of geochemical conditions on plant phytochemistry. In particular, high concentrations of dissolved salts can affect their biosynthesis of natural products. Detoxification is most likely an important aspect for the plant, but additional natural products can also give it an expanded range of bioactivities. During the phytochemical analysis a Palicourea luxurians plant collected in a sulfate-rich environment (near the Río Sucio, Costa Rica) showed an interesting natural product in this regard. The structure of this compound was determined using spectroscopic and computational methods (NMR, MS, UV, IR, CD, optical rotation, quantum chemical calculations) and resulted in a megastigmane sulfate ester possessing a β-ionone core structure, namely blumenol C sulfate (1, C₁₃H₂₂O₅S). The levels of sulfur and sulfate ions in the leaves of the plant were determined using elemental analysis and compared to the corresponding levels in comparable plant leaves from a less sulfate-rich environments. The analyses show the leaves from which we isolated blumenol C sulfate (1) to contain 35% more sulfur and 80% more sulfate than the other samples. Antimicrobial and antioxidant activities of compound 1 were tested against Escherichia coli, E. coli ampR and Bacillus subtilis as well as measured using complementary in vitro FRAP and ATBS assays, respectively. These bioactivities are comparable to those determined for structurally related megastigmanes. The sulfur and sulfate content of the plant leaves from the sulfate-rich environment was significantly higher than that of the other plants. Against this background of salt stress, we discuss a possible biosynthesis of blumenol C sulfate (1). Furthermore, there appears to be no benefit for the plant in terms of extended bioactivities. Hence, the formation of blumenol C sulfate (1) probably primarily serves the plant detoxification process.

Anti-Inflammatory Effects of Aralia elata Extract Against Dextran Sodium Sulfate-Induced Colitis in Mice and Raw 264.7 Macrophage Cells Exposed to Lipopolysaccharide: First Report

Aralia elata (AE) is an anti-inflammatory, polyphenolic containing medicinal plant. However, little is known about AE and its application to ulcerative colitis (UC). This study aimed to confirm AE extract's antioxidant and anti-inflammatory effects in vivo and in vitro. The in vitro antioxidant activity was evaluated by measuring total polyphenol and flavonoid content in AE extract. AE extract (10 000 mg/L) contained 186.8 mg GAE/g polyphenol and 81.9 mg QE/g flavonoid. Mice were divided into 6 groups, including control, which received normal saline, and treatment groups, which received dextran sodium sulfate (DSS) with or without AE extract (250, 500, and 1000 mg/kg). RAW 264.7 macrophage cells were divided into 2 groups: control and treatment. RAW 264.7 macrophage cells treated with sterile double distilled water, 1 mg/L lipopolysaccharide (LPS), and AE extracts (25, 50, 75, 100 µg/mL) were used to assess the cytotoxicity and anti-inflammatory activity. High-performance liquid chromatography, enzyme-linked immunosorbent assay (ELISA) kits, and histology were employed to analyze the AE extract contents, nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6, as oxidative stress markers. In addition, the disease activity index (DAI) and cytotoxicity were determined in mice and cells, respectively. High-performance liquid chromatography analysis revealed that AE extract is rich in chlorogenic acid (96 ± 0.01 mg/g). DSS increased the DAI and levels of TNF-α, IL-1β, and immune cell infiltration compared with those of the control animals. Furthermore, LPS eventually reduced cell viability and increased the levels of NO, TNF-α, IL-1β, and IL-6 in contrast to control cells. After treatment, a noticeable reduction was observed in the levels of DAI, NO, TNF-α, IL-1β, and IL-6 compared to those without AE treatments. Overall, AE extract is safe and had anti-inflammatory properties. Therefore, AE extract can be considered a potential pre-treatment supplement for UC.

Palicourea tomentosa (Aubl.) Borhidi: Microscopy, chemical composition and the analgesic, anti-inflammatory and anti-acetylcholinesterase potential

ETHNOPHARMACOLOGICAL RELEVANCE

Palicourea tomentosa (Aubl.) Borhidi (synonym Psychotria poeppigiana Müll. Arg.) leaves are used in the popular treatments of inflammation and pain; however, there are no scientific studies demonstrating their activity as the methanolic extract of P. tomentosa.

AIM OF STUDY

This study was undertaken to investigate the potential antioxidant, anti-acetylcholinesterase, anti-hyperalgesic, anti-nociceptive and anti-inflammatory properties, as well as the chemical composition and concentrations of constituents of the methanolic extract of P. tomentosa leaves (MEPT). The study also analyzes the micromorphology and histochemistry of leaves of P. tomentosa.

MATERIALS AND METHODS

The MEPT was analysed by ultra-high-pressure liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS/MS). The concentrations of total phenols, flavonoids, flavonols and condensed tannin were determined. The micromorphology and histochemistry of leaves were performed using standard reagents, light and field emission scanning electron microscopy, beyond energy-dispersive X-ray spectroscopy. The antioxidant activity was evaluated for DPPH, β-carotene and MDA. The anti-inflammatory activity of MEPT (30, 100, and 300 mg/kg) was assayed in carrageenan-induced models of paw oedema, mechanical hyperalgesia (Von Frey), cold allodynia (acetone) and pleurisy in mice. The anti-nociceptive potential of MEPT (30, 100, and 300 mg/kg) was evaluated by the formalin method in mice. The anti-acetylcholinesterase properties were evaluated in vivo in four rat brain structures.

RESULTS

The total ion chromatogram of MEPT demonstrated two alkaloids, one coumarin, one iridoid and two terpene derivatives. The highest phenol, flavonoid, flavonol and condensed tannin concentrations were found in the extract. A comprehensive explanation of the leaf micromorphology and histochemistry was presented. MEPT was significantly inhibited by the DPPH, β-carotene and MDA models. MEPT (30, 100 and 300 mg/kg) reduced the inflammation and hyperalgesic parameters in a carrageenan model and reduced formalin-induced nociception in both phases, which were cold sensitivity and oedema formation. The oral administration of 30 and 100 mg/kg MEPT significantly inhibited AChE activity in the frontal cortex.

CONCLUSION

This is the first chemical and biological study performed with a P. tomentosa methanolic extract and anatomical and histochemical analysis. The present study showed that MEPT inhibited pain and inflammatory parameters contributing, at least in part, to explain the popular use of this plant as analgesic natural agent. Also, anatomical and histochemistry of leaves described in the present study provide microscopical information, which aids species identification.

Ultrasonic-assisted extraction of polyphenolic compounds from Paederia scandens (Lour.) Merr. Using deep eutectic solvent: optimization, identification, and comparison with traditional methods

Ultrasonic-assisted extraction (UAE) coupled with deep eutectic solvent (DES) is a novel, efficient and green extraction method for phytochemicals. In this study, the effects of 16 DESs coupled with UAE on the extraction rate of polyphenols from Paederia scandens (Lour.) Merr. (P. scandens), an edible and medicinal herb, were investigated. DES synthesised with choline chloride and ethylene glycol at a 1:2 M ratio resulted in the highest extractability. Moreover, the effects of extraction parameters were investigated by using a two-level factorial experiment followed by response surface methodology The optimal parameters (water content in DES of 49.2%, the actual ultrasonic power of 72.4 W, and ultrasonic time of 9.7 min) resulted in the optimal total flavonoid content (TFC) (27.04 mg CE/g DW), ferric-reducing antioxidant power (FRAP) value (373.27 μmol Fe(Ⅱ)E/g DW) and 2,2'-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid radical (ABTS⁺) value (48.64 μmol TE/g DW), closely matching the experimental results. Furthermore, a comparison study demonstrated that DES-UAE afforded the higher TFC and FRAP value than traditional extraction methods. 36 individual polyphenolic compounds were identified and quantified by ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) in P. scandens extracts, and of which 30 were found in the extracts obtained by DES-UAE. Additionally, DES-UAE afforded the highest sum of individual polyphenolic compound content. These results revealed that DES-UAE enhanced the extraction efficiency for polyphenols and provided a scientific basis for further processing and utilization of P. scandens.

Antitumoral and Anticholinesterasic Activities of the Seven Species from Rubiaceae

BACKGROUND

The genus Psychotria and Palicourea are reported as a source of alkaloids and iridoids, which exhibit biological activities. This study aimed to evaluate antiproliferative and anticholinesterase activities and quantification of the alkaloids of seven species among the genus found in Mato Grosso do Sul region in Brazil.

METHODS

Concentrations of alkaloids were measured spectrophotometrically. The extracts were submitted to antiproliferative activity against ten cell lines. The anticholinesterase activity of the extracts was developed using brain structures of male Wistar rats: cerebral cortex, hippocampus, hypothalamus and striatum by the Ellman method.

RESULTS

Alkaloids from Psychotria and Palicourea species were quantified which showed values of 47.6 to 21.9 µg/g. Regarding the antiproliferative potential, Palicourea crocea demonstrated selectivity against the 786-0 cell line (GI50: 22.87 µg/mL). Psychotria leiocarpa inhibited cell growth against OVCAR-3 (GI50: 3.28 µg/mL), K-562 (GI50: 5.26 µg/mL), HaCaT (GI50: 27.20 µg/mL), PC-3 (GI50: 34.92 µg/mL), MCF-7 (GI50: 35.80 µg/mL) and P. capillacea showed activity against OVCAR-3 (GI50: 2.33 µg/ml) and U251 (GI50: 16.66 µg/ml). The effect of acetylcholinesterase inhibition was more effective in the hippocampus, demonstrating inhibition for Paliourea crocea, Psychotria deflexa, P. brachybotrya and P. leiocarpa of 70%, 57%, 50% and 40%, respectively, followed by P. poeppigiana and P. capillacea, inhibiting 21%, compared to the control.

CONCLUSION

Herein, the present work showed for the first time, anticholinesterasic and antiproliferative activities of extracts of Palicourea and Psychotria seem to be mainly associated with the levels of alkaloids in the leaves of these species.

Rediscovery of Chamisso's type specimens of Hawaiian Psychotria (Rubiaceae, Psychotrieae) in the herbarium of the Natural History Museum, Vienna

Between 1815 and 1818, Count Nikolai Romanzoff funded an expedition of the Russian brig Rurik. Besides their primary goal to discover the Northeast Passage, their aim was to collect scientific specimens, for which the botanist Adelbert von Chamisso and the entomologist Johann Friedrich von Eschscholtz were commissioned. On the Hawaiian Islands, they collected two unknown endemic species that Chamisso and Diederich Franz Leonhard von Schlechtendal later described as Coffeakaduana and C.mariniana, both now assigned to the large and complex genus Psychotria (Rubiaceae, Psychotrieae). The private herbarium of Chamisso is now preserved at the Komarov Botanical Institute, St. Petersburg (LE). In the late 1930s, their type collections of Psychotriakaduana and P.mariniana were sent out on loan for study, but got lost in transit during the aftermath of the Second World War. No extant original material was found during a subsequent revision of Hawaiian Psychotria and both species were consequently neotypified. These neotypes are superseded by the here-reported rediscovery of original material in the herbarium of Stephan Ladislaus Endlicher preserved at the Natural History Museum, Vienna (W) and these specimens are here designated as lectotypes. As both are rather fragmentary, the former neotypes are additionally designated as epitypes. In addition, some peculiarities and details of the expedition and its collections are noted.

Chemodiversity of tryptamine-derived alkaloids in six Costa Rican Palicourea species (Rubiaceae-Palicoureeae)

We report 14 harmala and tryptamine-iridoid alkaloids with various tri-, tetra- and pentacyclic cores from leaves and stem bark of six species of the large and complex neotropical genus Palicourea. Among them is the previously undescribed compound deoxostrictosamide which is related to strictosamide, a key intermediate in camptothecin biosynthesis. In addition, we describe the occurrence of 1,2,3,4-tetrahydronorharman-1-one for the first time within Rubiaceae and ophiorine A and B, two alkaloids with an unusual core bearing a betaine function and a zwitterion as new for the genus. Although the other compounds are already known from other species, their degree of structural diversity highlights the remarkable biosynthetic capabilities of the genus Palicourea. Furthermore, the present paper provides additional support for the hypothesis that tryptamine-iridoid alkaloids represent a distinct chemosystematic feature for the genus Palicourea.

Two new combinations, lectotypifications and a new name for Costa Rican Palicourea s.l

Species of the complex and diverse genera Psychotria and Palicourea are common but little-known elements in many tropical forest ecosystems. DNA-phylogenetic studies and a re-evaluation of morphological characters have recently shown that species of Psychotria subg. Heteropsychotria are nested within Palicourea s.l., which was traditionally separated by exhibiting a bird-pollinated (vs. insect-pollinated) pollination syndrome. In order to render both genera monophyletic groups, species of subg. Heteropsychotria need to be transferred to Palicourea s.l. For Central American species, most of the necessary combinations have already been made. In the course of ongoing research on the phytochemical characterization of species and clades of Costa Rican Palicourea s.l., the nomenclature of Mesoamerican species was revised. As a result, two new combinations and a new name are proposed here: Palicourea horquetensis (Dwyer & Hayden) A. C. Berger & C. M. Taylor is based on Rudgea horquetensis Dwyer & Hayden, Palicourea tonduzii (K. Krause) A. C. Berger is based on Cephaelis tonduzii K. Kraus and Palicourea longiinvolucrata A. C. Berger replaces Psychotria hispidula Standl. In addition, two lectotypes are designated.