Pleonotoquinones, Cytotoxic Oxepinenaphthoquinones from Pleonotoma jasminifolia.

Two unusual naphthoquinones, named here as pleonotoquinones A (1) and B (2), were isolated along with two known anthraquinones (3 and 4) via chromatographic separations of an ethyl acetate extract of the roots of Pleonotoma jasminifolia. Compounds 1 and 2 are the first examples of quinones bearing a 2-methyloxepine moiety. The compounds were isolated with the aid of mass spectrometry and molecular networking, and their structures were resolved using 1D and 2D NMR and HRESIMS data. The isolated compounds were evaluated for their antiproliferative activity against human cancer cell lines, and compounds 1 and 2 displayed cytotoxicity against human colon cancer HCT116 cells (IC50 = 2.6 µM for compound 1 and IC50 = 4.3 µM for compound 2) and human liver cancer HepG2 cells (IC50 = 1.9 µM for compound 1 and IC50 = 6.4 µM for compound 2).

Chemistry and Pharmacology of Bergenin or Its Derivatives: A Promising Molecule.

Bergenin is a glycosidic derivative of trihydroxybenzoic acid that was discovered in 1880 by Garreau and Machelart from the rhizomes of the medicinal plant Bergenia crassifolia (currently: Saxifraga crassifolia-Saxifragaceae), though was later isolated from several other plant sources. Since its first report, it has aroused interest because it has several pharmacological activities, mainly antioxidant and anti-inflammatory. In addition to this, bergenin has shown potential antimalarial, antileishmanial, trypanocidal, antiviral, antibacterial, antifungal, antinociceptive, antiarthritic, antiulcerogenic, antidiabetic/antiobesity, antiarrhythmic, anticancer, hepatoprotective, neuroprotective and cardioprotective activities. Thus, this review aimed to describe the sources of isolation of bergenin and its in vitro and in vivo biological and pharmacological activities. Bergenin is distributed in many plant species (at least 112 species belonging to 34 families). Both its derivatives (natural and semisynthetic) and extracts with phytochemical proof of its highest concentration are well studied, and none of the studies showed cytotoxicity for healthy cells.

A novel eudesmol derivative from the leaf essential oil of Guatteria friesiana (Annonaceae) and evaluation of the antinociceptive activity.

In the present study, it was evaluated the chemical composition and the antinociceptive activity of the essential oil obtained from the leaves of Guatteria friesiana. Seven compounds corresponding to 96.2% of the crude essential oil were identified. The main components identified were the mixture of ß-eudesmol and α-eudesmol (58.1%), and γ-eudesmol (16.8%). A new α-eudesmol derivative, named 5-hydroxy-α-eudesmol, was isolated together with the known compounds ß-eudesmol and a mixture of α-eudesmol, ß-eudesmol and γ-eudesmol of the essential oil. The chemical structures were determined by 1D and 2D NMR, and MS experiments. Essential oil has significant antinociceptive properties, which are related probably with the involvement of the opioid receptors and K+-ATP channels.

Synthesis of chalcone derivatives by Claisen-Schmidt condensation and in vitro analyses of their antiprotozoal activities.

Chalcone is a molecule with known biological activities. Based on this, a series of chalcone derivatives bearing methyl, phenyl or furanyl substituents at different positions of A and B rings were synthesised, characterised, and evaluated regarding antiprotozoal activity. Molecules were synthesised via base catalyzed Claisen-Schmidt condensation and characterised by IR and NMR spectral data. Antiprotozoal activity against Phytomonas serpens, Leishmania amazonensis and Acanthamoeba polyphaga was performed. All compounds inhibited more than 50% of the growth of P. serpens while five had this effect on L. amazonensis and all of them no more than 35% of inhibition on A. polyphaga. Remarkably interesting antiprotozoal effects were recorded with compound 5, with IC50 of 1.59 µM for P. serpens and 11.49 µM for L. amazonensis. The addition of a naphthyl group to the B ring can be postulated to be the cause of the 10 times increase observed in its trypanocidal activity.

Duguetia pycnastera Sandwith (Annonaceae) Leaf Essential Oil Inhibits HepG2 Cell Growth In Vitro and In Vivo.

Duguetia pycnastera Sandwith (Annonaceae) is a tropical tree that can be found in the Guyanas, Bolivia, Venezuela, and Brazil. In Brazil, it is popularly known as "ata", "envira", "envira-preta", and "envira-surucucu". In the present work, we investigated the in vitro and in vivo HepG2 cell growth inhibition capacity of D. pycnastera leaf essential oil (EO). The chemical composition of the EO was determined by GC−MS and GC−FID analyses. The alamar blue assay was used to examine the in vitro cytotoxicity of EO in cancer cell lines and non-cancerous cells. In EO-treated HepG2 cells, DNA fragmentation was measured by flow cytometry. The in vivo antitumor activity of the EO was assessed in C.B-17 SCID mice xenografted with HepG2 cells treated with the EO at a dosage of 40 mg/kg. Chemical composition analysis displayed the sesquiterpenes α-gurjunene (26.83%), bicyclogermacrene (24.90%), germacrene D (15.35%), and spathulenol (12.97%) as the main EO constituents. The EO exhibited cytotoxicity, with IC50 values ranging from 3.28 to 39.39 µg/mL in the cancer cell lines SCC4 and CAL27, respectively. The cytotoxic activity of the EO in non-cancerous cells revealed IC50 values of 16.57, 21.28, and >50 µg/mL for MRC-5, PBMC, and BJ cells, respectively. An increase of the fragmented DNA content was observed in EO-treated HepG2 cells. In vivo, EO displayed tumor mass inhibition activity by 47.76%. These findings imply that D. pycnastera leaf EO may have anti-liver cancer properties.

Antitumor Effect of Guatteria olivacea R. E. Fr. (Annonaceae) Leaf Essential Oil in Liver Cancer.

Guatteria olivacea R. E. Fries (synonym Guatteria punctata (Aubl.) R.A. Howard) is a tree of 10-27 m tall popularly known as "envira-bobó", "envira-fofa", "envireira", "embira", "embira-branca", "embira-preta", envira-branca", and "envira-preta", which can be found in the Brazilian Amazon biome. In this study, we evaluated the cytotoxic and antitumor effects of the essential oil (EO) obtained from the leaves of G. olivacea against liver cancer using HepG2 cells as a model. EO was obtained using a hydrodistillation Clevenger-type apparatus and was qualitatively and quantitatively characterized using GC-MS and GC-FID, respectively. The alamar blue assay was used to assess the cytotoxic potential of EO in a panel of human cancer cell lines and human non-cancerous cells. In HepG2 cells treated with EO, YO-PRO-1/propidium iodide staining, cell cycle distribution, and reactive oxygen species (ROS) were examined. In C.B-17 SCID mice with HepG2 cell xenografts, the efficacy of the EO (20 and 40 mg/kg) was tested in vivo. GC-MS and GC-FID analyses showed germacrene D (17.65%), 1-epi-cubenol (13.21%), caryophyllene oxide (12.03%), spathulenol (11.26%), (E)-caryophyllene (7.26%), bicyclogermacrene (5.87%), and δ-elemene (4.95%) as the major constituents of G. olivacea leaf EO. In vitro cytotoxicity of EO was observed, including anti-liver cancer action with an IC50 value of 30.82 µg/mL for HepG2 cells. In HepG2 cells, EO treatment increased apoptotic cells and DNA fragmentation, without changes in ROS levels. Furthermore, the EO inhibited tumor mass in vivo by 32.8-57.9%. These findings suggest that G. olivacea leaf EO has anti-liver cancer potential.

Essential Oils of Duguetia Species A. St. Hill (Annonaceae): Chemical Diversity and Pharmacological Potential.

Duguetia A. St. Hill (Annonaceae) is recognized as one of the major genera with approximately 100 species, 67 of which are found in Brazil (29 of those are endemic). They are arboreal species with edible fruits known as "pindaíba", "pindaíva" "pinha", and "envira" in Brazil. Many Duguetia species, in particular, have been used in traditional medicine to treat renal colic, stomachache, rheumatism, cough, toothache, muscle pain, fever, gastrointestinal pain, and breathing difficulties. In this study, we reviewed the chemical constituents and pharmacological properties of essential oils (EOs) from Duguetia species. A total of 12 species were found, along with their EO chemical constituents and bioactivities. Bicyclogermacrene, humulene epoxide II, spathulenol, germacrene D, caryophyllene oxide, viridiflorene, α-pinene, ß-caryophyllene, and ß-pinene were the main chemical constituents reported. The pharmacological effects of Duguetia species EOs included anti-inflammatory, antinociceptive, antibacterial, antifungal, antioxidant, anti-trypanosoma, cytotoxic and antitumor properties. This information adds to our understanding of the potential of the EOs of Duguetia species.

Tingenone and 22-hydroxytingenone target oxidative stress through downregulation of thioredoxin, leading to DNA double-strand break and JNK/p38-mediated apoptosis in acute myeloid leukemia HL-60 cells.

Acute myeloid leukemia (AML) is the most lethal form of leukemia. Standard anti-AML treatment remains almost unchanged for decades. Tingenone (TG) and 22-hydroxytingenone (22-HTG) are quinonemethide triterpenes found in the Amazonian plant Salacia impressifolia (Celastraceae), with cytotoxic properties in different histological types of cancer cells. In the present work, we investigated the anti-AML action mechanism of TG and 22-HTG in the AML HL-60 cell line. Both compounds exhibited potent cytotoxicity in a panel of cancer cell lines. Mechanistic studies found that TG and 22-HTG reduced cell growth and caused the externalization of phosphatidylserine, the fragmentation of internucleosomal DNA and the loss of mitochondrial transmembrane potential in HL-60 cells. In addition, pre-incubation with Z-VAD(OMe)-FMK, a pan-caspase inhibitor, prevented TG- and 22-HTG-induced apoptosis, indicating cell death by apoptosis via a caspase-dependent pathway. The analysis of the RNA transcripts of several genes indicated the interruption of the cellular antioxidant system, including the downregulation of thioredoxin, as a target for TG and 22-HTG. The application of N-acetyl-cysteine, an antioxidant, completely prevented apoptosis induced by TG and 22-HTG, indicating activation of the apoptosis pathway mediated by oxidative stress. Moreover, TG and 22-HTG induced DNA double-strand break and phosphorylation of JNK2 (T183/Y185) and p38α (T180/Y182), and co-incubation with SP 600125 (JNK/SAPK inhibitor) and PD 169316 (p38 MAPK inhibitor) partially prevented apoptosis induced by TG and 22-HTG. Together, these data indicate that TG and 22-HTG are new candidate for anti-AML therapy targeting thioredoxin.

Benzylated Dihydroflavones and Isoquinoline-Derived Alkaloids from the Bark of Diclinanona calycina (Annonaceae) and Their Cytotoxicities.

Diclinanona calycina R. E. Fries popularly known as "envira", is a species of the Annonaceae family endemic to Brazil. In our ongoing search for bioactive compounds from Annonaceae Amazon plants, the bark of D. calycina was investigated by classical chromatography techniques that yielded thirteen compounds (alkaloids and flavonoids) described for the first time in D. calycina as well as in the genus Diclinanona. The structure of these isolated compounds were established by extensive analysis using 1D/2D-NMR spectroscopy in combination with MS. The isolated alkaloids were identified as belonging to the subclasses: simple isoquinoline, thalifoline (1); aporphine, anonaine (2); oxoaporphine, liriodenine (3); benzyltetrahydroisoquinolines, (S)-(+)-reticuline (4); dehydro-oxonorreticuline (3,4-dihydro-7-hydroxy-6-methoxy-1-isoquinolinyl)(3-hydroxy-4-methoxyphenyl)-methanone) (5); (+)-1S,2R-reticuline Nß-oxide (6); and (+)-1S,2S-reticuline Nα-oxide (7); tetrahydroprotoberberine, coreximine (8); and pavine, bisnorargemonine (9). While the flavonoids belong to the benzylated dihydroflavones, isochamanetin (10), dichamanetin (11), and a mixture of uvarinol (12) and isouvarinol (13). Compound 5 is described for the first time in the literature as a natural product. The cytotoxic activity of the main isolated compounds was evaluated against cancer and non-cancerous cell lines. Among the tested compounds, the most promising results were found for the benzylated dihydroflavones dichamanetin (10), and the mixture of uvarinol (12) and isouvarinol (13), which presented moderate cytotoxic activity against the tested cancer cell lines (<20.0 µg·mL-1) and low cytotoxicity against the non-cancerous cell line MRC-5 (>25.0 µg·mL-1). Dichamanetin (11) showed cytotoxic activity against HL-60 and HCT116 with IC50 values of 15.78 µg·mL-1 (33.70 µmol·L-1) and 18.99 µg·mL-1 (40.56 µmol·L-1), respectively while the mixture of uvarinol (12) and isouvarinol (13) demonstrated cytotoxic activity against HL-60, with an IC50 value of 9.74 µg·mL-1, and HCT116, with an IC50 value of 17.31 µg·mL-1. These cytotoxic activities can be attributed to the presence of one or more hydroxybenzyl groups present in these molecules as well as the position in which these groups are linked. The cytotoxic activities of reticuline, anonaine and liriodenine have been previously established, with liriodenine being the most potent compound.

Essential Oil from Bark of Aniba parviflora (Meisn.) Mez (Lauraceae) Reduces HepG2 Cell Proliferation and Inhibits Tumor Development in a Xenograft Model.

Aniba parviflora (Meisn.) Mez (Lauraceae) is an aromatic plant of the Amazon rainforest, which has a tremendous commercial value in the perfumery industry; it is popularly used as flavoring sachets and aromatic baths. In Brazilian folk medicine, A. parviflora is used to treat victims of snakebites. Herein, we analyzed the chemical composition of A. parviflora bark essential oil (EO) and its effect on the growth of human hepatocellular carcinoma HepG2 cells in vitro and in vivo. EO was obtained by hydrodistillation and characterized by GC-MS and GC-FID. The main constituents of EO were linalool (16.3±3.15), α-humulene (14.5±2.41 %), δ-cadinene (10.2±1.09 %), α-copaene (9.51±1.12 %) and germacrene B (7.58±2.15 %). Initially, EO's cytotoxic effect was evaluated against five cancer cell lines (HepG2, MCF-7, HCT116, HL-60 and B16-F10) and one non-cancerous one (MRC-5), using the Alamar blue method after 72 h of treatment. The calculated IC50 values were 9.05, 22.04, >50, 15.36, 17.57, and 30.46 µg/mL, respectively. The best selectivity was for HepG2 cells with a selective index of 3.4. DNA Fragmentation and cell cycle distribution were quantified in HepG2 cells by flow cytometry after a treatment period of 24 and 48 h. The effect of EO on tumor development in vivo was evaluated in a xenograft model using C.B-17 SCID mice engrafted with HepG2 cells. In vivo tumor growth inhibition of HepG2 xenograft at the doses of 40 and 80 mg/kg were 12.1 and 62.4 %, respectively.

Flavonoid glycosides and their putative human metabolites as potential inhibitors of the SARS-CoV-2 main protease (Mpro) and RNA-dependent RNA polymerase (RdRp).

BACKGROUND: Since the World Health Organization (WHO) declared Coronavirus disease 2019 (COVID-19) to be a pandemic infection, important severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) non-structural proteins (nsp) have been analysed as promising targets in virtual screening approaches. Among these proteins, 3-chymotrypsin-like cysteine protease (3CLpro), also named main protease, and the RNA-dependent RNA polymerase (RdRp), have been identified as fundamental targets due to its importance in the viral replication stages. OBJECTIVES: To investigate, in silico, two of the most abundant flavonoid glycosides from Dysphania ambrosioides; a medicinal plant found in many regions of the world, along with some of the putative derivatives of these flavonoid glycosides in the human organism as potential inhibitors of the SARS-CoV-2 3CLpro and RdRp. METHODS: Using a molecular docking approach, the interactions and the binding affinity with SARS-CoV-2 3CLpro and RdRp were predicted for quercetin-3-O-rutinoside (rutin), kaempferol-3-O-rutinoside (nicotiflorin) and some of their glucuronide and sulfate derivatives. FINDINGS: Docking analysis, based on the crystal structure of 3CLpro and RdRp, indicated rutin, nicotiflorin, and their glucuronide and sulfate derivatives as potential inhibitors for both proteins. Also, the importance of the hydrogen bond and π-based interactions was evidenced for the presumed active sites. MAIN CONCLUSIONS: Overall, these results suggest that both flavonoid glycosides and their putative human metabolites can play a key role as inhibitors of the SARS-CoV-2 3CLpro and RdRp. Obviously, further researches, mainly in vitro and in vivo experiments, are necessary to certify the docking results reported here, as well as the adequate application of these substances. Furthermore, it is necessary to investigate the risks of D. ambrosioides as a phytomedicine for use against COVID-19.

In vitro and in vivo inhibition of HCT116 cells by essential oils from bark and leaves of Virola surinamensis (Rol. ex Rottb.) Warb. (Myristicaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Virola surinamensis (Rol. ex Rottb.) Warb. (Myristicaceae), popularly known in Brazil as "mucuíba", "ucuúba", "ucuúba-branca" or "ucuúba do igapó", is a medicinal plant used to treat a variety of diseases, including infections, inflammatory processes and cancer. AIM OF THE STUDY: In the present work, we investigated the chemical constituents and the in vitro and in vivo inhibition of human colon carcinoma HCT116 cells by essential oils obtained from the bark (EOB) and leaves (EOL) of V. surinamensis. MATERIALS AND METHODS: EOB and EOL were obtained by hydrodistillation and analyzed via gas chromatography with flame ionization detection and gas chromatography coupled to mass spectrometry. In vitro cytotoxic activity was determined in cultured cancer cells HCT116, HepG2, HL-60, B16-F10 and MCF-7 and in a non-cancerous cell line MRC-5 by the Alamar blue assay after 72 h of treatment. Annexin V/propidium iodide staining, mitochondrial transmembrane potential and cell cycle distribution were evaluated by flow cytometry in HCT116 cells treated with essential oils after 24 and 48 h of treatment. The cells were also stained with May-Grunwald-Giemsa to analyze cell morphology. In vivo antitumor activity was evaluated in C.B-17 SCID mice with HCT116 cells. RESULTS: The main constituents in EOB were aristolene (28.0 ± 3.1%), α-gurjunene (15.1 ± 2.4%), valencene (14.1 ± 1.9%), germacrene D (7.5 ± 0.9%), δ-guaiene (6.8 ± 1.0%) and ß-elemene (5.4 ± 0.6%). On the other hand, EOL displayed α-farnesene (14.5 ± 1.5%), ß-elemene (9.6 ± 2.3%), bicyclogermacrene (8.1 ± 2.0%), germacrene D (7.4 ± 0.7%) and α-cubebene (5.6 ± 1.1%) as main constituents. EOB showed IC50 values for cancer cells ranging from 9.41 to 29.52 µg/mL for HCT116 and B16-F10, while EOL showed IC50 values for cancer cells ranging from 7.07 to 26.70 µg/mL for HepG2 and HCT116, respectively. The IC50 value for a non-cancerous MRC-5 cell was 34.7 and 38.93 µg/mL for EOB and EOL, respectively. Both oils induced apoptotic-like cell death in HCT116 cells, as observed by the morphological characteristics of apoptosis, externalization of phosphatidylserine, mitochondrial depolarization and fragmentation of internucleosomal DNA. At a dose of 40 mg/kg, tumor mass inhibition rates were 57.9 and 44.8% in animals treated with EOB and EOL, respectively. CONCLUSIONS: These data indicate V. surinamensis as possible herbal medicine in the treatment of colon cancer.

Essential oil from leaves of Conobea scoparioides (Cham. & Schltdl.) Benth. (Plantaginaceae) causes cell death in HepG2 cells and inhibits tumor development in a xenograft model.

Conobea scoparioides (Cham. & Schltdl.) Benth. (syn. Sphaerotheca scoparioides Cham. & Schldtl.) (Plantaginaceae), popularly known as "pataqueira", "vassourinha-do-brejo" and/or "hierba-de-sapo", is a popular medicinal plant used to treat leishmaniasis, pain and beriberi. In addition, inhibition of cell adhesion, antioxidant, cytotoxic and leishmanicidal activities of compounds or fractions of C. scoparioides have been reported. In the present work, chemical constituents and in vitro and in vivo anti-liver cancer potential of essential oil (EO) from leaves of C. scoparioides were investigated using human hepatocellular carcinoma HepG2 cells as a cell model. EO was obtained by hydrodistillation using a Clevenger-type apparatus and characterized by GC-MS and GC-FID. The in vitro cytotoxic effect was evaluated on three human cancer cell lines (MCF-7, HepG2 and HCT116) and one human non-cancerous cell line (MRC-5) using the Alamar blue assay. Phosphatidylserine externalization and cell cycle distribution were quantified in HepG2 cells by flow cytometry after 48 h incubation. The effectiveness of EO in anti-liver cancer model was studied with HepG2 cells grafted on C.B. 17 SCID mice. The main constituents of EO were thymol methyl ether (62 %), thymol (16 %) and α-phellandrene (14 %). EO displayed an in vitro cytotoxic effect against all human cancer cell lines and caused externalization of phosphatidylserine and DNA fragmentation in HepG2 cells, suggesting induction of apoptotic-like cell death. In vivo tumor mass inhibition of 36.7 and 55.8 % was observed for treatment with EO at doses of 40 and 80 mg/kg, respectively. These results indicate in vitro and in vivo anti-liver cancer potential of EO from leaves of C. scoparioides.

Cyperus articulatus L. (Cyperaceae) Rhizome Essential Oil Causes Cell Cycle Arrest in the G2/M Phase and Cell Death in HepG2 Cells and Inhibits the Development of Tumors in a Xenograft Model.

Cyperus articulatus L. (Cyperaceae), popularly known in Brazil as "priprioca" or "piriprioca", is a tropical and subtropical plant used in popular medical practices to treat many diseases, including cancer. In this study, C. articulatus rhizome essential oil (EO), collected from the Brazilian Amazon rainforest, was addressed in relation to its chemical composition, induction of cell death in vitro and inhibition of tumor development in vivo, using human hepatocellular carcinoma HepG2 cells as a cell model. EO was obtained by hydrodistillation using a Clevenger-type apparatus and characterized qualitatively and quantitatively by gas chromatography coupled to mass spectrometry (GC-MS) and gas chromatography with flame ionization detection (GC-FID), respectively. The cytotoxic activity of EO was examined against five cancer cell lines (HepG2, HCT116, MCF-7, HL-60 and B16-F10) and one non-cancerous one (MRC-5) using the Alamar blue assay. Cell cycle distribution and cell death were investigated using flow cytometry in HepG2 cells treated with EO after 24, 48 and 72 h of incubation. The cells were also stained with May-Grunwald-Giemsa to analyze the morphological changes. The anti-liver-cancer activity of EO in vivo was evaluated in C.B-17 severe combined immunodeficient (SCID) mice with HepG2 cell xenografts. The main representative substances of this EO sample were muskatone (11.6%), cyclocolorenone (10.3%), α-pinene (8.26%), pogostol (6.36%), α-copaene (4.83%) and caryophyllene oxide (4.82%). EO showed IC50 values for cancer cell lines ranging from 28.5 µg/mL for HepG2 to >50 µg/mL for HCT116, and an IC50 value for non-cancerous of 46.0 µg/mL (MRC-5), showing selectivity indices below 2-fold for all cancer cells tested. HepG2 cells treated with EO showed cell cycle arrest at G2/M along with internucleosomal DNA fragmentation. The morphological alterations included cell shrinkage and chromatin condensation. Treatment with EO also increased the percentage of apoptotic-like cells. The in vivo tumor mass inhibition rates of EO were 46.5-50.0%. The results obtained indicate the anti-liver-cancer potential of C. articulatus rhizome EO.

In vitro and in vivo growth inhibition of human acute promyelocytic leukemia HL-60 cells by Guatteria megalophylla Diels (Annonaceae) leaf essential oil.

Guatteria megalophylla Diels (Annonaceae) is an 8-10 m tall tree that grows near streams and is widely spread throughout Colombian, Ecuadorian, Peruvian, Brazilian and Guianese Amazon rainforest. Herein, we investigated for the first time the chemical composition and in vitro and in vivo anti-leukemia potential of G. megalophylla leaf essential oil (EO) using human promyelocytic leukemia HL-60 cells as model. EO was obtained by a hydrodistillation clevenger-type apparatus and characterized quali- and quantitatively by GC-MS and GC-FID, respectively. In vitro cytotoxic potential of EO was evaluated in human cancer cell lines (HL-60, MCF-7 CAL27, HSC-3, HepG2 and HCT116) and in human non-cancer cell line (MRC-5) by Alamar blue method. Annexin V/propidium iodide staining, cell cycle distribution and reactive oxygen species (ROS) were assessed by flow cytometry for HL-60 cells treated with EO. In vivo efficacy of EO (50 and 100 mg/kg) was evaluated in C.B-17 SCID mice with HL-60 cell xenografts. Chemical composition analyses showed spathulenol, γ-muurolene, bicyclogermacrene, ß-elemene and δ-elemene as main constituents of assayed sample. EO displayed in vitro cytotoxicity, including anti-leukemia effect with IC50 value of 12.51 µg/mL for HL-60 cells. EO treatment caused augment of phosphatidylserine externalization and DNA fragmentation without increasing of ROS in HL-60 cells. In vivo tumor mass inhibition rates of EO was 16.6-48.8 %. These data indicate anti-leukemia potential of G. megalophylla leaf EO.

Flavonoid glycosides and their putative human metabolites as potential inhibitors of the SARS-CoV-2 main protease (Mpro) and RNA-dependent RNA polymerase (RdRp)

BACKGROUND Since the World Health Organization (WHO) declared Coronavirus disease 2019 (COVID-19) to be a pandemic infection, important severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) non-structural proteins (nsp) have been analysed as promising targets in virtual screening approaches. Among these proteins, 3-chymotrypsin-like cysteine protease (3CLpro), also named main protease, and the RNA-dependent RNA polymerase (RdRp), have been identified as fundamental targets due to its importance in the viral replication stages. OBJECTIVES To investigate, in silico, two of the most abundant flavonoid glycosides from Dysphania ambrosioides; a medicinal plant found in many regions of the world, along with some of the putative derivatives of these flavonoid glycosides in the human organism as potential inhibitors of the SARS-CoV-2 3CLpro and RdRp. METHODS Using a molecular docking approach, the interactions and the binding affinity with SARS-CoV-2 3CLpro and RdRp were predicted for quercetin-3-O-rutinoside (rutin), kaempferol-3-O-rutinoside (nicotiflorin) and some of their glucuronide and sulfate derivatives. FINDINGS Docking analysis, based on the crystal structure of 3CLpro and RdRp, indicated rutin, nicotiflorin, and their glucuronide and sulfate derivatives as potential inhibitors for both proteins. Also, the importance of the hydrogen bond and π-based interactions was evidenced for the presumed active sites. MAIN CONCLUSIONS Overall, these results suggest that both flavonoid glycosides and their putative human metabolites can play a key role as inhibitors of the SARS-CoV-2 3CLpro and RdRp. Obviously, further researches, mainly in vitro and in vivo experiments, are necessary to certify the docking results reported here, as well as the adequate application of these substances. Furthermore, it is necessary to investigate the risks of D. ambrosioides as a phytomedicine for use against COVID-19.

In vitro and in vivo anti-leukemia activity of the stem bark of Salacia impressifolia (Miers) A. C. Smith (Celastraceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Salacia impressifolia (Miers) A. C. Smith (family Celastraceae) is a traditional medicinal plant found in the Amazon Rainforest known as "miraruíra", "cipó-miraruíra" or "panu" and is traditionally used to treat dengue, flu, inflammation, pain, diabetes, male impotency, renal affections, rheumatism and cancer. AIM OF THE STUDY: The aim of this study was to investigate in vitro and in vivo anti-leukemia activity of the stem bark of S. impressifolia in experimental models. MATERIALS AND METHODS: The in vitro cytotoxic activity of extracts, fractions and quinonemethide triterpenes (22-hydroxytingenone, tingenone and pristimerin) from the stem bark of S. impressifolia in cultured cancer cells was determined. The in vivo antitumor activity of the ethyl acetate extract (EAE) and of its fraction (FEAE.3) from the stem bark of S. impressifolia was assessed in C.B-17 severe combined immunodeficient (SCID) mice engrafted with human promyelocytic leukemia HL-60 cells. RESULTS: The extract EAE, its fraction FEAE.3, and quinonemethide triterpenes exhibited potent cytotoxicity against cancer cell lines, including in vitro anti-leukemia activity against HL-60 and K-562 cells. Moreover, extract EAE and its fraction FEAE.3 inhibited the in vivo development of HL-60 cells engrafted in C.B-17 SCID mice. Tumor mass inhibition rates were measured as 40.4% and 81.5% for the extract EAE (20 mg/kg) and for its fraction FEAE.3 (20 mg/kg), respectively. CONCLUSIONS: Ethyl acetate extract and its fraction from the stem bark of S. impressifolia exhibit in vitro and in vivo anti-leukemia activity that can be attributed to their quinonemethide triterpenes. These data confirm the ethnopharmacological use of this species and may contribute to the development of a novel anticancer herbal medicine.

Antitumor Effect of the Essential Oil from the Leaves of Croton matourensis Aubl. (Euphorbiaceae).

Croton matourensis Aubl. (synonym Croton lanjouwensis Jabl.), popularly known as "orelha de burro", "maravuvuia", and/or "sangrad'água", is a medicinal plant used in Brazilian folk medicine as a depurative and in the treatment of infections, fractures, and colds. In this work, we investigated the chemical composition and in vitro cytotoxic and in vivo antitumor effects of the essential oil (EO) from the leaves of C. matourensis collected from the Amazon rainforest. The EO was obtained by hydrodistillation using a Clevenger-type apparatus and characterized qualitatively and quantitatively by gas chromatography coupled to mass spectrometry (GC⁻MS) and gas chromatography with flame ionization detection (GC⁻FID), respectively. In vitro cytotoxicity of the EO was assessed in cancer cell lines (MCF-7, HCT116, HepG2, and HL-60) and the non-cancer cell line (MRC-5) using the Alamar blue assay. Furthermore, annexin V-FITC/PI staining and the cell cycle distribution were evaluated with EO-treated HepG2 cells by flow cytometry. In vivo efficacy of the EO (40 and 80 mg/kg/day) was demonstrated in C.B-17 severe combined immunodeficient (SCID) mice with HepG2 cell xenografts. The EO included ß-caryophyllene, thunbergol, cembrene, p-cymene, and ß-elemene as major constituents. The EO exhibited promising cytotoxicity and was able to cause phosphatidylserine externalization and DNA fragmentation without loss of the cell membrane integrity in HepG2 cells. In vivo tumor mass inhibition rates of the EO were 34.6% to 55.9%. Altogether, these data indicate the anticancer potential effect of C. matourensis.

Cytotoxic Alkaloids from the Stem of Xylopia laevigata.

Xylopia laevigata (Annonaceae), known locally as "meiú" or "pindaíba", is widely used in folk medicine in Northeastern Brazil. In the present work, we performed phytochemical analyses of the stem of X. laevigata, which led to the isolation of 19 alkaloids: (-)-roemerine, (+)-anonaine, lanuginosine, (+)-glaucine, (+)-xylopine, oxoglaucine, (+)-norglaucine, asimilobine, (-)-xylopinine, (+)-norpurpureine, (+)-N-methyllaurotetanine, (+)-norpredicentrine, (+)-discretine, (+)-calycinine, (+)-laurotetanine, (+)-reticuline, (-)-corytenchine, (+)-discretamine and (+)-flavinantine. The in vitro cytotoxic activity toward the tumor cell lines B16-F10 (mouse melanoma), HepG2 (human hepatocellular carcinoma), K562 (human chronic myelocytic leukemia) and HL-60 (human promyelocytic leukemia) and non-tumor peripheral blood mononuclear cells (PBMCs) was tested using the Alamar Blue assay. Lanuginosine, (+)-xylopine and (+)-norglaucine had the highest cytotoxic activity. Additionally, the pro-apoptotic effects of lanuginosine and (+)-xylopine were investigated in HepG2 cells using light and fluorescence microscopies and flow cytometry-based assays. Cell morphology consistent with apoptosis and a marked phosphatidylserine externalization were observed in lanuginosine- and (+)-xylopine-treated cells, suggesting induction of apoptotic cell death. In addition, (+)-xylopine treatment caused G2/M cell cycle arrest in HepG2 cells. These data suggest that X. laevigata is a potential source for cytotoxic alkaloids.

7,7-Dimethylaporphine and Other Alkaloids from the Bark of Guatteria friesiana.

Phytochemical investigation of the bark of Guatteria friesiana afforded 12 new aporphines (1-12), along with nine known alkaloids (13-21). The structures of the new alkaloids were determined on the basis of spectroscopic data interpretation. The cytotoxic activity of the isolated compounds against a small panel of tumor cell lines was assessed using the Alamar blue assay.