The Amazonian Rubiaceae species Uncaria guianensis (UG) is locally used as anti-inflammatory, antitumor, antidiabetic, anti-ulcers, and others. The phenolic content of its leaves is characterized by the great predominance of the flavonoid kaempferol-3,7-O-(α)-L-dirhamnoside (kaempferitrin). The present study quantitatively evaluates the kaempferitrin content in the leaves and branches of cultivated and wild UG specimens collected in different locations of the Brazilian Amazon rainforest by employing high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD). Besides, the understanding of the polyphenol profile performed by electron spray ionization is deepened by tandem mass spectrometry analysis (ESI-MS/MS), using a previously approached leaf UG extract, and the flavonoid quercetin-3,7-O-(α)-L-dirhamnoside was first isolated from UG. All samples showed quite similar qualitative polyphenol profiles. Kaempferitrin in UG ranged from 1.1 to 1.9 mg 100 mg-1 for dry leaves of adult wild plants, 0.3 to 0.7 mg 100 mg-1 for dry leaves of cultivated young plants and 0.00 to 0.04 mg 100 mg-1 for dry branches of adult wild plants. Besides suggesting the distribution of kaempferitrin in the species, these results reinforce this flavonol as a suitable chemical marker for UG leaves and the products derived from them.

The leaf MeOH extract of Psychotria leiocarpa (Rubiaceae) showed in vitro non-cytotoxic and anti-dengue virus serotype 2 (DENV2) activity in human hepatocarcinoma cell lineage (HepG2). A one-step and cost-effective reversed-phase solid-phase extraction method based on high-performance liquid chromatography (HPLC) parameters allowed the isolation, directly from this bioactive extract, of the monoterpene indole alkaloids: N-glucopyranosyl vincosamide (1), vincosamide (2) and strictosidinic acid (3). The chemical structures were characterized based on 1D and 2D nuclear magnetic resonance (NMR), UV and high-resolution mass spectra (HRMS). The methodology has also allowed yielding a polyphenolic-rich fraction that was analyzed by high-performance liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MS/MS) revealing two flavonol triglycosides (4, 5) and three caffeoylquinic acid isomers (6-8). Compound 3 is reported for the first time in P. leiocarpa and all the phenolic compounds (4-8) are described for the first time in the genus Psychotria. Compounds 1-3 showed to be non-cytotoxic and anti-dengue active towards DENV2, highlighting vincosamide (2).

Leaves of Eugenia florida DC. have been used in folk medicine as hypotensive, hypoglycemic, antipyretic and for gastrointestinal disorders, among others. In this study dried leaves were extracted with ethanol and the extract was partitioned with hexane, CHCl3, EtOAc, BuOH and water to afford triterpenoid- and polyphenol-rich fractions which were analyzed by GC-MS and UFLC-DAD-ESI-Ion Trap-MSn. All fractions were tested against the proliferation of leukemic K562 and human melanoma SK-Mel-28 cell lines and for their ability to scavenge DPPH radical. Twenty-nine compounds were fully identified (among triterpenic and phenolic acids, flavonol- and dihydroflavonol-monoglyclosides) based on mass fragmentation patterns and comparison to standards and/or literature data. The ability to scavenge DPPH radical resulted in the following order: BuOH ≈ EtOAc > crude extract ≈ Water >> CHCl3 >> hexane; with the two most active reaching half of the TBHQ control potency (EC50 6.59 ± 0.03 µg mL-1). On testing against the proliferation of K562 and SK-Mel-28 cell lines, the most significant inhibitions were achieved on the former by the crude extract (IC50 12 µg mL-1) and the hexane and EtOAc fractions at 15 µg mL-1.

The species Piper ottonoides Yuncker (Piperaceae), known as “joão-brandim”, is a shrub that occurs in the Brazilian Amazon rainforest. Its roots and leaves are used in traditional medicine as local anesthetic to treat toothache and sore throat. In this study, the structural characterization in mixture of isobutyl amides present in semi-purified fractions from fruits, leaves, stems and roots of P. ottonoides was achieved by employing gas chromatography-mass spectrometry (GC-MS) and a combination of nuclear magnetic resonance (NMR) techniques (1H, 1H-1H COSY, 1H-13C HSQC, 1H-13C HMBC, TOCSY and 1H-1H J-RES). The MS fragmentation patterns and the NMR chemical shifts, multiplicities, coupling constants and the signal correlations in the two-dimensional spectra were carefully analyzed also taking into account some key elements of differentiation among the compounds. The data set allowed identifying unequivocally the new amide N-isobutyl-7-(4’- methoxyphenyl)-2E,4E-heptadienamide, which we named ottonoidenamide as well as piperovatine and chingchengenamide A in all parts of the plant, the additional presence of pipercallosine and pipercallosidine in roots and of dihydropiperlonguminine in fruits and leaves. The presence of piperovatine and pipercallosine in P. ottonoides should be associated to its traditional use.

Uncaria tomentosa (Willd.) DC. e U. guianensis (Aubl.) Gmel., conhecidas como unha-de-gato, são trepadeiras lenhosas nativas das florestas tropicais amazônica e central-americana. As espécies contêm, em diferentes proporções, alcalóides indólicos e oxindólicos, triterpenóides glicosilados, esteróides e proantocianidinas. U. tomentosa é quimicamente identificada pelo perfil e conteúdo de alcalóides oxindólicos, ao passo que U. guianensis não possui um marcador químico efetivo. Nesse trabalho descreve-se o isolamento de canferol-3,7-O-(α)-dirramnosídeo (canferitrina) pela primeira vez em espécies do gênero Uncaria. A triagem para essa substância em folhas, galhos ou cascas das duas espécies por CCD e CLAE-DAD-EM demonstrou a presença de canferitrina apenas nas folhas e galhos de U. guianensis, numa proporção cerca de trinta e seis vezes maior nas folhas do que nos galhos. Estes resultados revelaram a seletividade da U. guianensis em produzir o flavonóide glicosilado, sugerindo esta substância como um marcador químico potencial para a espécie.

Uncaria tomentosa (Willd.) DC. and U. guianensis (Aubl.) Gmel., known as cat's claw, are large woody vines native to the Amazonian and Central American rainforests. The species contain, in different proportions, indole and oxindole alkaloids, triterpenoid glycosides, sterols and proanthocyanidins. U. tomentosa can be chemically identified by its oxindole alkaloid profile and content, whereas U. guianensis has no satisfactorily established chemical markers. This work describes, for the first time, the isolation of kaempferol-3,7-O-(α)-dirhamnoside (kaempferitrin) in Uncaria species. Screening for this compound in leaves, stems or bark of both species through TLC and HPLC-DAD-MS showed the presence of kaempferitrin only in the leaves and stems of U. guianensis, at a ratio almost thirty six times greater in the leaves than in the stems. These results reveal the selectivity of U. guianensis to produce this bioactive flavonoid glycoside, and suggest this compound as a potential chemical marker for the species.

Uncaria tomentosa (Willd.) DC. e Uncaria guianensis (Aubl.) Gmel., conhecidas comercialmente como unha-de-gato, são trepadeiras lenhosas nativas das florestas tropicais amazônica e central-americana. Essas espécies de Rubiaceae enfrentam ultimamente um eminente risco de extinção devido tanto ao extrativismo indiscriminado quanto ao desflorestamento de seus habitats naturais. Esse trabalho descreve métodos de cultivo in vitro para as duas espécies, analisando o perfil e o teor dos alcalóides oxindólicos pentacíclicos marcadores por CLAE no material vegetal obtido. Os resultados mostraram que os métodos desenvolvidos foram capazes de produzir plantas com perfil e teor dos alcalóides alvos similares à plantas nativas e cultivadas in vivo, com a vantagem adicional de produção em menor tempo de mudas próprias para plantio no campo. Os dados evidenciaram que o cultivo in vitro pode ser uma ferramenta viável para a produção das duas espécies com impacto na sua comercialização e na preservação das florestas.

Uncaria tomentosa (Willd.) DC. and Uncaria guianensis (Aubl.) Gmel., commercially known as cat's claw, are large woody vines native of the Amazon and Central America rainforests. These Rubiaceae species face nowadays an imminent risk of extinction due to indiscriminate harvesting in the wild as well as to increasing deforestation of their natural habitat. This work describes in vitro cultivation methods for both species with determination, by HPLC, of the pentacyclic oxindole alkaloid contents and profiles of the plant material. The results have proved that the methods we developed were able to produce plants with alkaloid profiles and contents similar to the wild and in vivo cultivated species, and with the additional advantage of producing suitable young plants in a shorter period of time. The data showed that the in vitro technique can be a feasible tool for the growth of the species, and may thus be important for their commercialization and for their conservation as a forest resource.