A bioactive spirolactone iridoid and triterpenoids from Himatanthus sucuuba

Potential anti-diabetic isoprenoids and a long-chain δ-lactone from frangipani (Plumeria rubra)

A decoction of Plumeria rubra flowers has been used traditionally for the treatment of diabetes in China and Mexico. Chemical investigations on the bioactive constituents of these flowers led to the isolation of 30 compounds, including the four new compounds, one iridoiod (1), two triterpenoids (4, 5), and a long-chain δ-lactone (16). In addition, 26 known compounds (2, 3, 6-15, 17-30) are also reported. All of these compounds were identified on the basis of spectroscopic data interpretation and the absolute configurations of compound 4, 5, 16 were determined by Mosher's method. Compounds 1-4, 7, 8 and 16 showed moderate to significant inhibitory activities against α-glucosidase and protein tyrosine phosphatase 1B, with 4 having IC₅₀ values of 19.45 μM and 0.21 μM, respectively.

Histopathological evaluation of latex of Bellaco-Caspi, Himatanthus sucuuba (Spruce) Woodson on wound healing effect in BALB/C mice

Background and Aim:

Himatanthus sucuuba (Spruce) Woodson (Apocynaceae) is a medicinal plant known as “Bellaco-Caspi” widely distributed in Loreto, Peru. In the Peruvian traditional medicine, the latex of the plant is used for the treatment of wounds, inflammation, ulcers, and other ailments. This study aims to evaluate the wound healing effect of the latex of H. sucuuba in BALB/C albino mice.

Materials and Methods:

Thirty BALB/C male mice were used for wound healing study. In the experimental procedures, wound skin incision was performed at 2.0 cm in length until subcutaneous on the paravertebral of each animal. Under locally anesthetized with procaine cream, the treatment was conducted. All the mice were divided into three groups, the control group (A), zinc oxide cream (B), and H. sucuuba latex (C). The entire surface of the wound was treated for all the groups, and the treatments were performed daily for 15 days. The experiments were stopped on days 1, 7, and 15, respectively.

Results:

The histopathological study of tissues revealed significant changes in wound healing effect in H. sucuuba latex compared to the control and B groups. Consequently, the mice treated with latex showed a significant reduction in epithelialization time and collagen formation. Furthermore, the latex showed a dose-dependent significant reduction of inflammation in the first 24 h of treatment.

Conclusion:

BALB/C mice treated with the latex of H. sucuuba possess a wound healing effect that can scientifically prove the traditional use of the plant as a wound healing agent.

Himatanthus Willd. ex Schult. (Apocynaceae): Review

The genus Himatanthus Wild. ex Schult. (Apocynaceae) includes about 13 species and five subspecies widely distributed in South America, especially Brazil. The phytochemical reports on this genus have revealed mainly triterpenes and iridoids. The plants are traditionally used as anthelmintic, antitumor, and antiinflammatory agents. The most used parts of the plant are its bark, leaves, and latex. This review emphasizes the phytochemical constituents and medicinal properties, which may help in future research. The research was conducted with data obtained from books about medicinal plants, theses, dissertations, and articles in refereed journals.

Plumericin inhibits proliferation of vascular smooth muscle cells by blocking STAT3 signaling via S-glutathionylation

The etiology of atherosclerosis and restenosis involves aberrant inflammation and proliferation, rendering compounds with both anti-inflammatory and anti-mitogenic properties as promising candidates for combatting vascular diseases. A recent study identified the iridoid plumericin as a new scaffold inhibitor of the pro-inflammatory NF-κB pathway in endothelial cells. We here examined the impact of plumericin on the proliferation of primary vascular smooth muscle cells (VSMC). Plumericin inhibited serum-stimulated proliferation of rat VSMC. It arrested VSMC in the G1/G0-phase of the cell cycle accompanied by abrogated cyclin D1 expression and hindered Ser 807/811-phosphorylation of retinoblastoma protein. Transient depletion of glutathione by the electrophilic plumericin led to S-glutathionylation as well as hampered Tyr705-phosphorylation and activation of the transcription factor signal transducer and activator of transcription 3 (Stat3). Exogenous addition of glutathione markedly prevented this inhibitory effect of plumericin on Stat3. It also overcame downregulation of cyclin D1 expression and the reduction of biomass increase upon serum exposure. This study revealed an anti-proliferative property of plumericin towards VSMC which depends on plumericin's thiol reactivity and S-glutathionylation of Stat3. Hence, plumericin, by targeting at least two culprits of vascular dysfunction -inflammation and smooth muscle cell proliferation -might become a promising electrophilic lead compound for vascular disease therapy.

Ligand- and Brønsted acid/base-switchable reaction pathways in gold(i)-catalyzed cycloisomerizations of allenoic acids

Competing gold-catalyzed cycloisomerizations of γ-allenoic acids are optimized through ligand and Brønsted acid/base effects, affording three distinct classes of lactones.

Identification of plumericin as a potent new inhibitor of the NF-κB pathway with anti-inflammatory activity in vitro and in vivo

BACKGROUND AND PURPOSE

The transcription factor NF-κB orchestrates many pro-inflammatory signals and its inhibition is considered a promising strategy to combat inflammation. Here we report the characterization of the natural product plumericin as a highly potent inhibitor of the NF-κB pathway with a novel chemical scaffold, which was isolated via a bioactivity-guided approach, from extracts of Himatanthus sucuuba, an Amazonian plant traditionally used to treat inflammation-related disorders.

EXPERIMENTAL APPROACH

A NF-κB luciferase reporter gene assay was used to identify NF-κB pathway inhibitors from H. sucuuba extracts. Monitoring of TNF-α-induced expression of the adhesion molecules VCAM-1, ICAM-1 and E-selectin by flow cytometry was used to confirm NF-κB inhibition in endothelial cells, and thioglycollate-induced peritonitis in mice to confirm effects in vivo. Western blotting and transfection experiments were used to investigate the mechanism of action of plumericin.

KEY RESULTS

Plumericin inhibited NF-κB-mediated transactivation of a luciferase reporter gene (IC₅₀ 1 μM), abolished TNF-α-induced expression of the adhesion molecules VCAM-1, ICAM-1 and E-selectin in endothelial cells and suppressed thioglycollate-induced peritonitis in mice. Plumericin exerted its NF-κB pathway inhibitory effect by blocking IκB phosphorylation and degradation. Plumericin also inhibited NF-κB activation induced by transfection with the constitutively active catalytic subunit of the IκB kinase (IKK-β), suggesting IKK involvement in the inhibitory action of this natural product.

CONCLUSION AND IMPLICATIONS

Plumericin is a potent inhibitor of NF-κB pathways with a new chemical scaffold. It could be further explored as a novel anti-inflammatory lead compound.

Anti-mycobacterial activity of plumericin and isoplumericin against MDR Mycobacterium tuberculosis

BACKGROUND AND OBJECTIVES

Because of the developing resistance of Mycobacterium species against currently available anti-mycobacterial drugs, there is an urgent need for new drug development. In this study, we have evaluated the in vitro anti-mycobacterial activity of Plumeria bicolor extract and its phytoconstituents - plumericin and isoplumericin against multi-drug resistance Mycobacterium tuberculosis.

METHODS

The in vitro anti-mycobacterial activity of chloroform extract of P. bicolor, plumericin and isoplumericin were tested against M. tuberculosis (H37Rv) and four multi-drug resistant (MDR) clinical isolates by measuring the minimum inhibitory concentration (MIC) using MTT (Tetrazolium bromide [3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide]) assay. The extract and both compounds were further evaluated by standard assay procedures to determine their minimum bactericidal concentration (MBC). Cytotoxicity of these compounds was performed against J774G8 murine macrophage cell lines. The activity was represented in the mean (±SD) of duplicate samples from three independent assays.

RESULTS

Plumericin showed better activity against pan sensitive as well as four MDR strains of M. tuberculosis with MIC values of 2.1 ± 0.12, 1.3 ± 0.15, 2.0 ± 0.07, 1.5 ± 0.13 & 2.0 ± 0.14 μg/mL and MBC values of 3.6 ± 0.22, 2.5 ± 0.18, 3.8 ± 0.27, 2.9 ± 0.20 & 3.7 ± 0.32 μg/mL than isoplumericin, respectively. Interestingly, both isolated active compounds showed an advantage over rifampicin (80 times) and isoniazid (8 times) by being highly active against the MDR strains. The extract and both compounds were found to be non-toxic against J774G8 macrophages up to the used concentrations.

CONCLUSION

Plumericin showed more potent activity than isoplumericin. The excellent activity of these compounds against MDR strains opens a possibility of obtaining new anti-mycobacterial drug candidate in near future.

Pentacyclic triterpenes from Manilkara bidentata resin. Isolation, identification and biological properties

Three pentacyclic triterpenes were isolated for the first time from resinous plant Manilkara bidentata. Ultrasound-assisted extraction with ethanol was chosen after a comparison of various extraction methods. Analysis of the extract was performed by HPLC with evaporative light scattering detection and semi-preparative HPLC has enabled us to isolate two urs-12-enes (3β-O-acetyl-α-amyrin and 3β-O-trans cinnamyl-α-amyrin) and a lupane-type derivative (3β-O-trans cinnamyl lupeol). Structures were elucidated on the basis of HRESIMS, atmospheric pressure photoionization MS, and homo- and heteronuclear correlation NMR experiments. Antioxidant and anti-inflammatory activities were determined on Manilkara extract and isolated fractions. We have also investigated their action on collagen and fibronectin synthesis, two very important proteins of the extracellular matrix. Thus, Manilkara extract was able to decrease IL-1β and IL-8 pro-inflammatory cytokines. These activities exhibit the potential use of Manilkara extract as an anti-inflammatory and anti-aging ingredient for pharmaceutical and cosmetic industries.

Anti-inflammatory iridoids of botanical origin

Inflammation is a manifestation of a wide range of disorders which include; arthritis, atherosclerosis, Alzheimer's disease, inflammatory bowel syndrome, physical injury and infection amongst many others. Common treatment modalities are usually nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, paracetamol, indomethacin and ibuprofen as well as corticosteroids such as prednisone. These however, may be associated with a host of side effects due to non-selectivity for cyclooxygenase (COX) enzymes involved in inflammation and those with selectivity may be highly priced. Thus, there is a continuing search for safe and effective antiinflammatory molecules from natural sources. Research has confirmed that iridoids exhibit promising anti-inflammatory activity which may be beneficial in the treatment of inflammation. Iridoids are secondary metabolites present in various plants, especially in species belonging to the Apocynaceae, Lamiaceae, Loganiaceae, Rubiaceae, Scrophulariaceae and Verbenaceae families. Many of these ethnobotanicals have an illustrious history of traditional use alluding to their use to treat inflammation. Although iridoids exhibit a wide range of pharmacological activities such as cardiovascular, hepatoprotection, hypoglycaemic, antimutagenic, antispasmodic, anti-tumour, antiviral, immunomodulation and purgative effects this review will acutely focus on their anti-inflammatory properties. The paper aims to present a summary for the most prominent iridoid-containing plants for which anti-inflammatory activity has been demonstrated in vitro and / or in vivo.

Evaluation of nonpolar metabolites in plant extracts by 13C NMR spectroscopy

(13)C nuclear magnetic resonance (NMR) spectroscopy was explored as a simple and efficient technique for the quantitative analysis of nonpolar metabolites in plants. The method was first optimized with a mixture of known metabolites and then applied to the nonpolar leaf extracts of plants harvested in the Valencian community (eastern Spain) belonging to three different genera: Euphorbia (Euphorbiaceae), Araujia (Apocynaceae), and Morus (Moraceae). Furthermore, an exhaustive analysis of Euphorbia characias leaf and stem extracts from different geographic locations allowed that quantitative (13)C NMR spectroscopy is a suitable tool for metabolic profiling purpose.

Antiparasitic activity of plumericin & isoplumericin isolated from Plumeria bicolor against Leishmania donovani

BACKGROUND & OBJECTIVES

The severe toxicity, exorbitant cost and emerging resistance of Leishmania species against most of the currently used drugs underscores the urgent need for the alternative drugs. The present study evaluates in vitro anti-leishmanial activity of Plumeria bicolor and its isolated compounds.

METHODS

The in vitro anti-parasitic activity of chloroform extract of Plumeria bicolor, plumericin and isoplumericin were tested alongwith appropriate controls against promastigote and amastigote forms of Leishmania donovani using 96 well microtiter plate. The concentration used for assessing the anti-leishmanial activity of extract of Plumeria bicolor and both isolated compounds were 100 μg/ml and 15 μM, respectively. The viability of the cells was assessed by MTT assay. The cytotoxicity of these compounds was performed against J774G8 murine macrophage cells lines at the concentration of 30 μM.

RESULTS

The Plumeria bicolor extract showed activity with the IC 50 of 21±2.2 and 14±1.6 μg/ml against promastigote and amastigote forms of L. donovani, respectively. Plumericin consistently showed high activity with the IC 50 of 3.17±0.12 and 1.41±0.03 μM whereas isoplumericin showed the IC50 of 7.2±0.08 μM and 4.1±0.02 μM against promastigote and amastigote forms, respectively. Cytotoxic effect of the chloroform extract of P. bicolor, plumericin and isoplumericin was evaluated in murine macrophage (J774G8) model with CC50 value of 75±5.3 μg/ml, 20.6±0.5 and 24±0.7 μM, respectively.

INTERPRETATION & CONCLUSIONS

Our results indicated that plumericin showed more potent activity than isoplumericin and might be a promising anti-leishmanial agent against L. donovani.

Antifungal Activity of Plumericin and Isoplumericin

This study evaluated the in vitro antifungal activity of the chloroform extract of Plumeria bicolor and its phytoconstituents plumericin and isoplumericin against Candida species and Cryptococcus neoformans by measuring the Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC). Plumericin's consistently high activity against Candida albicans, C. krusei, C. glabrata, C. tropicalis and Cryptococcus neoformans was more potent than isoplumericin and the standard antifungal drug nystatin suggesting its potential as a drug candidate for candidiasis and cryptococcosis.

Antiproliferative effect of a traditional remedy, Himatanthus articulatus bark, on human cancer cell lines

ETHNOPHARMACOLOGICAL RELEVANCE

Himatanthus articulatus (Vahl) Woodson (Apocynaceae) is a tree occurring in the Amazon region. The local population uses its bark against to external tumors and cancer.

AIM OF THE STUDY

Evaluated the antiproliferative activity of the crude extract and their fractions against human tumors cells.

MATERIALS AND METHODS

The antiproliferative responses of the crude extract and their fractions were colorimetrically evaluated by sulforhodamine B (SRB) assay against HT-29 (colon adenocarcinoma); NCI-H460 (non-small cell lung carcinoma); MCF-7 (breast cancer); OVCAR-3 (ovarian adenocarcinoma) and RXF-393 (renal cell carcinoma) as well as against NIH-3T3 (mouse embryo fibroblast cell).

RESULTS

The cytotoxicity data from the crude extract allowed considering active only in the NCI-H460 cell line. However, the antiproliferative activity was much more pronounced at the chloroformic fraction in all cell lines tested. The butanolic fraction demonstrated activity against to HT-29, MCF-7, RXF-393 and OVCAR-3 cells. The ethyl acetate fraction demonstrated activity only in RXF-393 and the aqueous residue did not present antiproliferative effect.

CONCLUSIONS

Through the popular use we find that the crude extracts of Himatanthus articulatus bark displayed weak cytotoxic. However, the butanolic fraction showed to be active only against to tumor cell lines while chloroformic fraction possesses high activity being similar to the positive control. Both fractions have been selected for future bio-guided fractionation and isolation of active compounds.

Pharmacogenomics of Cameroonian traditional herbal medicine for cancer therapy

ETHNOPHARMACOLOGICAL RELEVANCE

A socio-economic burden associated with cancers is reported in Africa. Ethnopharmacological usages such as immune and skin disorders, inflammatory, and others chould be considered when selecting plants used to treat cancer, since these reflect disease states bearing relevance to cancer or a cancer symptoms.

MATERIALS AND METHODS

Documented compounds of Cameroonian medicinal plants were used as keywords in the National Cancer Institute (NCI) database to establish a library of cytotoxic compounds. Cellular and pharmacogenomic profiling was then performed for the 10 most cytotoxic natural products. By COMPARE and hierarchical cluster analyses, candidate genes were identified whose mRNA expression significantly predicted sensitivity or resistance of cell lines to the two most cytotoxic compounds.

RESULTS

Up to 974 compounds isolated from 148 medicinal plants were used as keywords in the NCI database to establish a library of 27 cytotoxic compounds. Two of the 10 most cytotoxic compounds, plumericin from Plumeria rubra and plumbagin from Diospyros crassiflora and Diospyros canaliculata, were analyzed in more detail. The IC(50) values for plumericin and plumbagin of 60 NCI cell lines were associated with the microarray-based transcriptome-wide mRNA expression. Genes products identified for plumericin activity are mainly involved in enzymatic activity, transcriptional processes or are structural constituents of ribosomes. Products identified for plumbagin activity are involved in several processes, but they are mostly the strucrural constituents of ribosomes or involved in enzymatic activity.

CONCLUSIONS

The most significant progress of the present investigation, the first of its kind ever reported for investigated natural product in Sub-Saharan Africa, was the connection between traditionally used medicinal plants and the mechanistic analysis, such as pharmacogenomics.

Antibacterial and antifungal activity of extracts and exudates of the Amazonian medicinal tree Himatanthus articulatus (Vahl) Woodson (common name: sucuba)

Himatanthus articulatus (Vahl) Woodson is a tree found in the northern Amazon savannahs (common name: sucuba) that is used in local Amerindian medicine. Leaf, bark and branch wood methanol extracts, sequentially obtained hexane, ethyl acetate and methanol extracts and latex were evaluated for antifungal and antibacterial activities against American Type Culture Collection (ATCC) and local clinical strains using the disc diffusion method. Methanol extracts and latex inhibited Candida albicans, leaf methanol extracts inhibited Staphylococcus aureus and Bacillus subtilis and bark methanol extracts inhibited B. subtilis. Active extracts inhibited the ATCC and clinical strains. Polar antifungal and antibacterial principles in latex and extracts are thought to be responsible for the inhibition.

A multipronged approach to the study of peruvian ethnomedicinal plants: a legacy of the ICBG-Peru Project

A multidisciplinary and international team of scientists was assembled in the early 1990s to conduct an ethnobotanical study of plants used by the Aguaruna people of the Peruvian Amazon forest. The initial ethnobotanical project, carried out under the auspices of an International Cooperative Biodiversity Grant (ICBG), led to the collection of approximately 4000 plant species. Some members of the original team of scientists have continued this collaboration by focusing on potential sources of new anticancer, anti-infective, and wound-healing agents. This effort has uncovered several secondary metabolites representing a wide variety of chemical diversity. In this short review we describe some bioactive compounds of interest as part of our continuing collaboration.

Isolation of cytotoxic metabolites from targeted peruvian amazonian medicinal plants

The antiproliferative bioassay-guided fractionation of five Peruvian plants, Doliocarpus dentatus, Picramnia sellowii, Strychnos mitscherlichii, Iryanthera juruensis, and Croton alnifolius, led to the isolation and identification of their different major cytotoxic constituents, betulinic acid (1), nataloe-emodin (2), bisnordihydrotoxyferine (4), 2',4'-dihydroxy-6'-methoxy-3,4-methylenedioxydihydrochalcone (5), and 2',4'-dihydroxy-4,6'-dimethoxydihydrochalcone (6) and 12-O-tetradecanoylphorbol-13-acetate (7), respectively. Eight human tumor cell lines and two nontumorigenic cell lines were used in this investigation. Their in vitro activity against Mycobacterium tuberculosis is also reported.

The Inhibition of Superoxide Anion Generation by Neutrophils from Viscum articulactum

Two new flavanones, (2S)-pinocembrin 7-O-[beta-D-apiosyl(1-->2)]-beta-D-glucoside (1), and (2S)-pinocembrin 7-O-[cinnamoyl(1-->5)-beta-D-apiosyl(1-->2)]-beta-D-glucoside (2) together with eighteen known compounds, which include five known flavanones, nine benzenoids, one inositol and three triterpenoids, were isolated and characterized from fresh Viscum articulactum. Structures of new compounds were determined by spectral analysis. Among them, oleanolic acid (18) showed a significant inhibition effect on superoxide anion generation by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP).