Indolizidine, antiinfective and antiparasitic compounds from Prosopis glandulosa var. glandulosa

An aza-Robinson Annulation Strategy for the Synthesis of Fused Bicyclic Amides: Synthesis of (±)-Coniceine and Quinolizidine

An aza-Robinson annulation strategy is described using a NaOEt-catalyzed conjugate addition of cyclic imides onto vinyl ketones, followed by a TfOH-mediated intramolecular aldol condensation to afford densely functionalized fused bicyclic amides. The potential use of these amides in the synthesis of alkaloids is demonstrated by the sequential conversion of appropriate precursors to (±)-coniceine and quinolizidine in two additional steps, thus allowing their preparation in overall 40 and 44% yields, respectively.

The potential role of plant secondary metabolites on antifungal and immunomodulatory effect

With the widespread use of antibiotic drugs worldwide and the global increase in the number of immunodeficient patients, fungal infections have become a serious threat to global public health security. Moreover, the evolution of fungal resistance to existing antifungal drugs is on the rise. To address these issues, the development of new antifungal drugs or fungal inhibitors needs to be targeted urgently. Plant secondary metabolites are characterized by a wide variety of chemical structures, low price, high availability, high antimicrobial activity, and few side effects. Therefore, plant secondary metabolites may be important resources for the identification and development of novel antifungal drugs. However, there are few studies to summarize those contents. In this review, the antifungal modes of action of plant secondary metabolites toward different types of fungi and fungal infections are covered, as well as highlighting immunomodulatory effects on the human body. This review of the literature should lay the foundation for research into new antifungal drugs and the discovery of new targets. KEY POINTS: • Immunocompromised patients who are infected the drug-resistant fungi are increasing. • Plant secondary metabolites toward various fungal targets are covered. • Plant secondary metabolites with immunomodulatory effect are verified in vivo.

Antimicrobial Properties of Chilean Native Plants: Future Aspects in Their Application in the Food Industry

Food contamination with microorganisms is responsible for food spoilage, deterioration and change of organoleptic properties of foods. Besides, the growth of pathogenic microorganisms can provoke serious health problems if food is consumed. Innovative packaging, such as active packaging, is increasing rapidly in the food industry, especially in applying antimicrobials into delivery systems, such as sachets. Chile is a relevant hotspot for biodiversity conservation and a source of unique bio-resources with antimicrobial potential. In this review, fifteen native plants with antimicrobial properties are described. Their antimicrobial effects include an effect against human pathogens. Considering the emergence of antimicrobial resistance, searching for new antimicrobials to design new strategies for food pathogen control is necessary. Chilean flora is a promising source of antimicrobials to be used in active packaging. However, further studies are required to advance from laboratory tests of their antimicrobial effects to their possible effects and uses in active films.

Health Benefits of the Diverse Volatile Oils in Native Plants of Ancient Ironwood-Giant Cactus Forests of the Sonoran Desert: An Adaptation to Climate Change?

We document the species richness and volatile oil diversity in Sonoran Desert plants found in the Arizona Uplands subdivision of this binational USA/Mexico region. Using floristics, we determined that more than 60 species of 178 native plants in the ancient ironwood-giant cactus forests emit fragrant biogenic volatile organic compounds (BVOCs), especially with the onset of summer monsoons. From these desert species, more than 115 volatile oils have been identified from one biogeographic region. For the 5 BVOCs most commonly associated with “forest bathing” practices in Asian temperate forests, at least 15 Sonoran Desert plant species emit them in Arizona Uplands vegetation. We document the potential health benefits attributed to each of 13 BVOCs in isolation, but we also hypothesize that the entire “suite” of BVOCs emitted from a diversity of desert plants during the monsoons may function synergistically to generate additional health benefits. Regular exposure to these BVOC health benefits may become more important to prevent or mitigate diseases of oxidative stress and other climate maladies in a hotter, drier world.

Antibacterial and Antioxidant Activities of Isolated Compounds from Prosopis africana Leaves

Prosopis africana (G. &Perr.) Taub (Mimosaceae) is a large tree native to dry tropical Africa and characteristic of dry leguminous forests. Different parts of this plant are used to treat wounds, skin infection, and to fight against cancer. Literature review indicated various pharmacological properties. Despite these medicinal properties, the chemical composition studies remain limited. This study aims to isolate and characterize secondary metabolites from P. africana leaves and evaluate their antibacterial and antioxidant properties. Air-dried powdered leaves of P. africana were macerated in methanol at room temperature and partitioned with ethyl acetate. The EtOAc extract was subjected successively to flash and column chromatographies in order to isolate compounds. The structure of the isolates was determined with help of spectroscopic data including 1D and 2D NMR experiments and comparison with literature data. The antibacterial activities were evaluated via determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The antioxidant activities were evaluated via gallic acid equivalent antioxidant capacity (GEAC) and diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays. The chemical investigation of the EtOAc extract led to the isolation of seven compounds: (2E, 6E) farnesylamine (1), myricetin-3-O-rhamnoside (2), bis(2-ethylhexyl) benzene-1,2-dicarboxylate (3), lupeol (4), ß-sitosterol (5), stigmasterol glycoside (6), and a mixture of bis(2-ethylhexyl) benzene-1,2-dicarboxylate (3) and bis(2-ethylhexyl) benzene-1,4-dicarboxylate (7) in ratio 1 : 2. Compound 1 is described here for the first time as a natural product with complete 1H and 13C assignments. Compounds 3 and 7 were identified as artefacts from dichloromethane. Sesquiterpene amine (1) is reported in Prosopis genus for the first time. Antibacterial and antioxidant activities of isolated compounds were investigated. Among the tested samples, the EtOAc extract and compound 2 exhibited the highest antioxidant (EC50 = 5.67–77.56 μg/mL; GEAC = 36.58–89.28 μg/mL) and antibacterial (MIC = 8–64 μg/mL) activities against gram-negative and gram-positive bacteria. The EtOAc extract and compound 2 from P. africana exhibited antibacterial activity through bacteriolytic effects and reduction of the antioxidant defenses in the bacterial cells. Furthermore, the chemotaxonomic significance of isolated compounds was discussed. The antibacterial and antioxidant activities of ethyl acetate extract and compound 2 can justify the traditional uses of P. africana leaves for the treatment of diseases related to bacterial infections. The presence of compounds 1, 2, and 4 in this plant should also be considered as valuable chemotaxonomic features.

Biologically active indolizidine alkaloids

Indolizidine alkaloids are chemical constituents isolated from various marine and terrestrial plants and animals, including but not limited to trees, fungi, ants, and frogs, with a myriad of important biological activities. In this review, we discuss the biological activity and pharmacological effects of indolizidine alkaloids and offer new avenues toward the discovery of new and better drugs based on these naturally occurring compounds.

Activating Imides with Triflic Acid: A General Intramolecular Aldol Condensation Strategy Toward Indolizidine, Quinolizidine, and Valmerin Alkaloids

A simple, inexpensive, step economic, and highly modular synthetic strategy to access izidine alkaloids is described. The key step is a TfOH-promoted intramolecular aldol condensation between enol and cyclic imide moieties. This cyclization strategy can be employed within an aza-Robinson annulation framework and represents a general tool to build fused bicyclic amines. To illustrate the power of this method, we describe the preparation of (±)-coniceine, (±)-quinolizidine, (±)-tashiromine, (±)-epilupinine, and the core of (±)-valmerins.

Prosopis Plant Chemical Composition and Pharmacological Attributes: Targeting Clinical Studies from Preclinical Evidence

Members of the Prosopis genus are native to America, Africa and Asia, and have long been used in traditional medicine. The Prosopis species most commonly used for medicinal purposes are P. africana, P. alba, P. cineraria, P. farcta, P. glandulosa, P. juliflora, P. nigra, P. ruscifolia and P. spicigera, which are highly effective in asthma, birth/postpartum pains, callouses, conjunctivitis, diabetes, diarrhea, expectorant, fever, flu, lactation, liver infection, malaria, otitis, pains, pediculosis, rheumatism, scabies, skin inflammations, spasm, stomach ache, bladder and pancreas stone removal. Flour, syrup, and beverages from Prosopis pods have also been potentially used for foods and food supplement formulation in many regions of the world. In addition, various in vitro and in vivo studies have revealed interesting antiplasmodial, antipyretic, anti-inflammatory, antimicrobial, anticancer, antidiabetic and wound healing effects. The phytochemical composition of Prosopis plants, namely their content of C-glycosyl flavones (such as schaftoside, isoschaftoside, vicenin II, vitexin and isovitexin) has been increasingly correlated with the observed biological effects. Thus, given the literature reports, Prosopis plants have positive impact on the human diet and general health. In this sense, the present review provides an in-depth overview of the literature data regarding Prosopis plants' chemical composition, pharmacological and food applications, covering from pre-clinical data to upcoming clinical studies.

The Biological Activity of Natural Alkaloids against Herbivores, Cancerous Cells and Pathogens

The growing incidence of microorganisms that resist antimicrobials is a constant concern for the scientific community, while the development of new antimicrobials from new chemical entities has become more and more expensive, time-consuming, and exacerbated by emerging drug-resistant strains. In this regard, many scientists are conducting research on plants aiming to discover possible antimicrobial compounds. The secondary metabolites contained in plants are a source of chemical entities having pharmacological activities and intended to be used for the treatment of different diseases. These chemical entities have the potential to be used as an effective antioxidant, antimutagenic, anticarcinogenic and antimicrobial agents. Among these pharmacologically active entities are the alkaloids which are classified into a number of classes, including pyrrolizidines, pyrrolidines, quinolizidines, indoles, tropanes, piperidines, purines, imidazoles, and isoquinolines. Alkaloids that have antioxidant properties are capable of preventing a variety of degenerative diseases through capturing free radicals, or through binding to catalysts involved indifferent oxidation processes occurring within the human body. Furthermore, these entities are capable of inhibiting the activity of bacteria, fungi, protozoan and etc. The unique properties of these secondary metabolites are the main reason for their utilization by the pharmaceutical companies for the treatment of different diseases. Generally, these alkaloids are extracted from plants, animals and fungi. Penicillin is the most famous natural drug discovery deriving from fungus. Similarly, marines have been used as a source for thousands of bioactive marine natural products. In this review, we cover the medical use of natural alkaloids isolated from a variety of plants and utilized by humans as antibacterial, antiviral, antifungal and anticancer agents. An example for such alkaloids is berberine, an isoquinoline alkaloid, found in roots and stem-bark of Berberis asculin P. Renault plant and used to kill a variety of microorganisms.

Efficacy of Prosopilosidine from Prosopis glandulosa var. glandulosa against Cryptococcus neoformans Infection in a Murine Model

In this study, 2,3-dihydro-1H-indolizinium alkaloid-prosopilosidine (PPD), that was isolated from Prosopis glandulosa, was evaluated against C. neoformans in a murine model of cryptococcosis. In vitro and in vivo toxicity of indolizidines were also evaluated. Mice were infected via the tail vein with live C. neoformans. Twenty-four hours post-infection, the mice were treated with PPD once a day (i.p.) or twice a day (bid) orally, or with amphotericin B (Amp B) intraperitoneally (IP), or with fluconazole (Flu) orally for 5 days. The brains of all of the animals were aseptically removed and the numbers of live C. neoformans were recovered. In vitro toxicity of indolizidine alkaloids was determined in HepG2 cells. PPD showed to be potent in vivo activity against C. neoformans at a dose of 0.0625 mg/kg by eliminating ~76% of the organisms compared to ~83% with Amp B (1.5 mg/kg). In addition, PPD was found to be equally efficacious, but less toxic, at either 0.125 or 0.0625 mg/kg compared to Amp B (1.5 mg/kg) when it was administered bid (twice a day) by an i.p. route. When tested by an oral route, PPD (10 mg/kg) showed potent activity in this murine model of cryptococcosis with ~82% of organisms eliminated from the brain tissue, whereas Flu (15 mg/kg) reduced ~90% of the infection. In vitro results suggest that quaternary indolizidines were less toxic as compared to those of tertiary bases. PPD (20 mg/kg) did not cause any alteration in the plasma chemistry profiles. These results indicated that PPD was active in eliminating cryptococcal infection by oral and i.p. routes at lower doses compared to Amp B. or Flu.

Antimalarial Activity of Plant Metabolites

Malaria, as a major global health problem, continues to affect a large number of people each year, especially those in developing countries. Effective drug discovery is still one of the main efforts to control malaria. As natural products are still considered as a key source for discovery and development of therapeutic agents, we have evaluated more than 2000 plant extracts against Plasmodium falciparum. As a result, we discovered dozens of plant leads that displayed antimalarial activity. Our phytochemical study of some of these plant extracts led to the identification of several potent antimalarial compounds. The prior comprehensive review article entitled “Antimalarial activity of plant metabolites” by Schwikkard and Van Heerden (2002) reported structures of plant-derived compounds with antiplasmodial activity and covered literature up to the year 2000. As a continuation of this effort, the present review covers the antimalarial compounds isolated from plants, including marine plants, reported in the literature from 2001 to the end of 2017. During the span of the last 17 years, 175 antiplasmodial compounds were discovered from plants. These active compounds are organized in our review article according to their plant families. In addition, we also include ethnobotanical information of the antimalarial plants discussed.

In vitro antileishmanial activity of Mexican medicinal plants

Aim of the study

To evaluate the anti-leishmanial activity and cytotoxicity of aqueous and organic extracts of ten plants used in Mexican traditional medicine as anti-parasitics.

Materials and methods

For the organic extracts, plant material was macerated in dichloromethane (CH₂Cl₂) and dichloromethane/methanol (CH₂Cl₂/MeOH) (1:1) during two weeks; the aqueous extracts were prepared by infusion. The extracts were tested against promastigotes and intracellular amastigotes of Leishmania amazonensis. The cytotoxicity was assayed in parallel on peritoneal macrophages of BALB/c mice.

Results

Four of the thirty extracts tested were active and selective against L. amazonensis promastigotes: Schinus molle (CH₂Cl₂ and CH₂Cl₂/MeOH), Lantana camara (CH₂Cl₂) and Prosopis laevigata (aqueous). These extracts had a median inhibitory concentration (IC₅₀) against intracellular amastigotes under 50 μg/mL and a selectivity index (SI) higher than 5, which indicates that they constitute valuable candidates to obtain secondary metabolites with leishmanicidal activity.

Conclusions

The results derived from this study indicate that L. camara, P. laevigata, and S. molle might provide interesting new leads for the development of antileishmanial drugs.

Aggregation Behavior of 6-Isocassine andN-Methyl-6-Isocassine: Insights into the Biological Mode of Action of Lipid Alkaloids

The aggregation behavior of 6-isocassine and N-methyl-6-isocassine, two piperidin-3-ol alkaloids isolated respectively from the barks of Prosopis nigra and P. affinis, was investigated using a combination of NOE experiments and diffusion measurements in solvents of varying polarity and hydrogen bonding capacity. While the NOE enhancements for N-methyl-6-isocassine are positive, regardless of the solvent, those for 6-isocassine shift from negative to positive when going from chloroform- d to methanol- d4solution. In addition, despite the self-diffusion coefficients of both compounds being virtually identical in methanol- d4, N-methyl-6-isocassine diffuses nearly twice as fast as the non-methylated alkaloid in chloroform- d. The changes in rotational and translational dynamics observed between solvents for 6-isocassine suggest that the molecule forms dimeric head-to-head aggregates in non-polar aprotic environments, a behavior that could help explain the biological mode of action that has been proposed for this type of alkaloids.

The Woodrat Gut Microbiota as an Experimental System for Understanding Microbial Metabolism of Dietary Toxins

The microbial communities inhabiting the alimentary tracts of mammals, particularly those of herbivores, are estimated to be one of the densest microbial reservoirs on Earth. The significance of these gut microbes in influencing the physiology, ecology and evolution of their hosts is only beginning to be realized. To understand the microbiome of herbivores with a focus on nutritional ecology, while evaluating the roles of host evolution and environment in sculpting microbial diversity, we have developed an experimental system consisting of the microbial communities of several species of herbivorous woodrats (genus Neotoma) that naturally feed on a variety of dietary toxins. We designed this system to investigate the long-standing, but experimentally neglected hypothesis that ingestion of toxic diets by herbivores is facilitated by the gut microbiota. Like several other rodent species, the woodrat stomach has a sacculated, non-gastric foregut portion. We have documented a dense and diverse community of microbes in the woodrat foregut, with several genera potentially capable of degrading dietary toxins and/or playing a role in stimulating hepatic detoxification enzymes of the host. The biodiversity of these gut microbes appears to be a function of host evolution, ecological experience and diet, such that dietary toxins increase microbial diversity in hosts with experience with these toxins while novel toxins depress microbial diversity. These microbial communities are critical to the ingestion of a toxic diet as reducing the microbial community with antibiotics impairs the host's ability to feed on dietary toxins. Furthermore, the detoxification capacity of gut microbes can be transferred from Neotoma both intra and interspecifically to naïve animals that lack ecological and evolutionary history with these toxins. In addition to advancing our knowledge of complex host-microbes interactions, this system holds promise for identifying microbes that could be useful in the treatment of diseases in humans and domestic animals.

Phloroglucinol and Terpenoid Derivatives from Hypericum cistifolium and H. galioides (Hypericaceae)

A new simple phloroglucinol derivative characterized as 1-(6-hydroxy-2,4-dimethoxyphenyl)-2-methyl-1-propanone (1) was isolated from Hypericum cistifolium (Hypericaceae) as a major constituent of the non-polar plant extract. Minor amounts of this new compound, in addition to two known structurally related phloroglucinol derivatives (2 and 3), and two new terpenoid derivatives characterized, respectively, as 2-benzoyl-3,3-dimethyl-4R,6S-bis-(3-methylbut-2-enyl)-cyclohexanone (4a) and 2-benzoyl-3,3-dimethyl-4S,6R-bis-(3-methylbut-2-enyl)-cyclohexanone (4b), were isolated from a related species, H. galioides Lam. The chemical structures were established using 2D-NMR spectroscopy and mass spectrometry. These compounds were evaluated in vitro for antimicrobial activity against a panel of pathogenic microorganisms and anti-inflammatory activity through inhibition of COX-1, COX-2, and 5-LOX catalyzed LTB4 formation.

Simple Indolizidine and Quinolizidine Alkaloids

This review of simple indolizidine and quinolizidine alkaloids (i.e., those in which the parent bicyclic systems are in general not embedded in polycyclic arrays) is an update of the previous coverage in Volume 55 of this series (2001). The present survey covers the literature from mid-1999 to the end of 2013; and in addition to aspects of the isolation, characterization, and biological activity of the alkaloids, much emphasis is placed on their total synthesis. A brief introduction to the topic is followed by an overview of relevant alkaloids from fungal and microbial sources, among them slaframine, cyclizidine, Steptomyces metabolites, and the pantocins. The important iminosugar alkaloids lentiginosine, steviamine, swainsonine, castanospermine, and related hydroxyindolizidines are dealt with in the subsequent section. The fourth and fifth sections cover metabolites from terrestrial plants. Pertinent plant alkaloids bearing alkyl, functionalized alkyl or alkenyl substituents include dendroprimine, anibamine, simple alkaloids belonging to the genera Prosopis, Elaeocarpus, Lycopodium, and Poranthera, and bicyclic alkaloids of the lupin family. Plant alkaloids bearing aryl or heteroaryl substituents include ipalbidine and analogs, secophenanthroindolizidine and secophenanthroquinolizidine alkaloids (among them septicine, julandine, and analogs), ficuseptine, lasubines, and other simple quinolizidines of the Lythraceae, the simple furyl-substituted Nuphar alkaloids, and a mixed quinolizidine-quinazoline alkaloid. The penultimate section of the review deals with the sizable group of simple indolizidine and quinolizidine alkaloids isolated from, or detected in, ants, mites, and terrestrial amphibians, and includes an overview of the "dietary hypothesis" for the origin of the amphibian metabolites. The final section surveys relevant alkaloids from marine sources, and includes clathryimines and analogs, stellettamides, the clavepictines and pictamine, and bis(quinolizidine) alkaloids.

Alkaloids: an overview of their antibacterial, antibiotic-enhancing and antivirulence activities

With reports of pandrug-resistant bacteria causing untreatable infections, the need for new antibacterial therapies is more pressing than ever. Alkaloids are a large and structurally diverse group of compounds that have served as scaffolds for important antibacterial drugs such as metronidazole and the quinolones. In this review, we highlight other alkaloids with development potential. Natural, semisynthetic and synthetic alkaloids of all classes are considered, looking first at those with direct antibacterial activity and those with antibiotic-enhancing activity. Potent examples include CJ-13,136, a novel actinomycete-derived quinolone alkaloid with a minimum inhibitory concentration of 0.1 ng/mL against Helicobacter pylori, and squalamine, a polyamine alkaloid from the dogfish shark that renders Gram-negative pathogens 16- to >32-fold more susceptible to ciprofloxacin. Where available, information on toxicity, structure-activity relationships, mechanisms of action and in vivo activity is presented. The effects of alkaloids on virulence gene regulatory systems such as quorum sensing and virulence factors such as sortases, adhesins and secretion systems are also described. The synthetic isoquinoline alkaloid virstatin, for example, inhibits the transcriptional regulator ToxT in Vibrio cholerae, preventing expression of cholera toxin and fimbriae and conferring in vivo protection against intestinal colonisation. The review concludes with implications and limitations of the described research and directions for future research.

Juliprosopine and juliprosine from prosopis juliflora leaves induce mitochondrial damage and cytoplasmic vacuolation on cocultured glial cells and neurons

Prosopis juliflora is a shrub largely used for animal and human consumption. However, ingestion has been shown to induce intoxication in animals, which is characterized by neuromuscular alterations induced by mechanisms that are not yet well understood. In this study, we investigated the cytotoxicity of a total alkaloid extract (TAE) and one alkaloid fraction (F32) obtained from P. juliflora leaves to rat cortical neurons and glial cells. Nuclear magnetic resonance characterization of F32 showed that this fraction is composed of a mixture of two piperidine alkaloids, juliprosopine (majority constituent) and juliprosine. TAE and F32 at concentrations between 0.3 and 45 μg/mL were tested for 24 h on neuron/glial cell primary cocultures. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test revealed that TAE and F32 were cytotoxic to cocultures, and their IC50 values were 31.07 and 7.362 μg/mL, respectively. Exposure to a subtoxic concentration of TAE or F32 (0.3-3 μg/mL) induced vacuolation and disruption of the astrocyte monolayer and neurite network, ultrastructural changes, characterized by formation of double-membrane vacuoles, and mitochondrial damage, associated with changes in β-tubulin III and glial fibrillary acidic protein expression. Microglial proliferation was also observed in cultures exposed to TAE or F32, with increasing levels of OX-42-positive cells. Considering that F32 was more cytotoxic than TAE and that F32 reproduced in vitro the main morphologic and ultrastructural changes of "cara torta" disease, we can also suggest that piperidine alkaloids juliprosopine and juliprosine are primarily responsible for the neurotoxic damage observed in animals after they have consumed the plant.

Cardioprotective and anti-hypertensive effects of Prosopis glandulosa in rat models of pre-diabetes

Aim

Obesity and type 2 diabetes present with two debilitating complications, namely, hypertension and heart disease. The dried and ground pods of Prosopis glandulosa (commonly known as the Honey mesquite tree) which is part of the Fabaceae (or legume) family are currently marketed in South Africa as a food supplement with blood glucose-stabilising and anti-hypertensive properties. We previously determined its hypoglycaemic effects, and in the current study we determined the efficacy of P glandulosa as anti-hypertensive agent and its myocardial protective ability.

Methods

Male Wistar rats were rendered either pre-diabetic (diet-induced obesity: DIO) or hypertensive (high-fat diet: HFD). DIO animals were treated with P glandulosa (100 mg/kg/day for the last eight weeks of a 16-week period) and compared to age-matched controls. Hearts were perfused ex vivo to determine infarct size. Biometric parameters were determined at the time of sacrifice. Cardiac-specific insulin receptor knock-out (CIRKO) mice were similarly treated with P glandulosa and infarct size was determined. HFD animals were treated with P glandulosa from the onset of the diet or from weeks 12–16, using captopril (50 mg/kg/day) as the positive control. Blood pressure was monitored weekly.

Results

DIO rats and CIRKO mice: P glandulosa ingestion significantly reduced infarct size after ischaemia–reperfusion. Proteins of the PI-3-kinase/PKB/Akt survival pathway were affected in a manner supporting cardioprotection. HFD model: P glandulosa treatment both prevented and corrected the development of hypertension, which was also reflected in alleviation of water retention.

Conclusion

P glandulosa was cardioprotective and infarct sparing as well as anti-hypertensive without affecting the body weight or the intra-peritoneal fat depots of the animals. Changes in the PI-3-kinase/PKB/Akt pathway may be causal to protection. Results indicated water retention, possibly coupled to vasoconstriction in the HFD animals, while ingestion of P glandulosa alleviated both. We concluded that treatment of pre-diabetes, type 2 diabetes or hypertension with P glandulosa poses possible beneficial health effects.

Perfluorinated Taddol Phosphoramidite as an L,Z-Ligand on Rh(I) and Co(-I): Evidence for Bidentate Coordination via Metal-C6F5 Interaction

Perfluorinated Taddol-based phosphoramidite, CKphos, is a highly selective ligand for formation of the vinylogous amide cycloadduct in the Rh(I) catalyzed [2+2+2] cycloaddition of alkenyl isocyanates and alkynes. CKphos overrides substrate bias of product selectivity in the cycloaddition, providing indolizinones in excellent product and enantioselectivities. Excellent selectivities are attributed to a shortened Rh-P bond and coordination of one C6F5 to rhodium via a Z-type interaction, making the phosphoramidite a bidentate L,Z-ligand on rhodium. Evidence for the shortened Rh-P and C6F5 coordination is provided by X-ray, NMR and DFT computation analyses. Additionally, an anionic cobalt complex with CKphos was synthesized and two Co-C6F5 interactions are seen. Rh(C2H4)Cl•CKphos catalyst in the [2+2+2] cycloaddition of alkenyl isocyanates and alkynes represents a rare example of metal-C6F5 Z-type interaction affecting selectivity in transition metal catalysis.

Isolation of natural products by low-pressure column chromatography

This chapter describes the isolation of natural products using low-pressure column chromatography (LPLC) and provides a brief summary of the adsorption and size exclusion processes involved in LPLC. Different types of stationary phases used in both adsorption and size exclusion LPLC are also presented with specific examples. Various operational parameters in relation to column packing (both wet and dry), column equilibration, sample application, and column development, and a summary of generic procedures for adsorption and size exclusion LPLC are also incorporated in this chapter. Throughout the chapter, several specific examples of the application of LPLC for the isolation of various natural products including alkaloids, coumarins, flavones, and saponins from various plants are given. Many of these examples include a combination of adsorption and size exclusion chromatography to obtain specific compounds.

Antiparasitic and antimicrobial isoflavanquinones from Abrus schimperi

The EtOH extract of Abrus schimperi (Fabaceae), collected in Kenya, demonstrated significant activity against Leishmania donovani promastigotes with IC50 value of 3.6 microg/mL. Bioassay-guided fractionation of CHCl3 fraction using Centrifugal Preparative TLC afforded two antiparasitic isoflavanquinones, namely amorphaquinone (1) and pendulone (2). They displayed IC50 values of 0.63 microg/mL and 0.43 microg/mL, respectively, against L. donovani promastigotes. Both the compounds were also evaluated against L. donovani axenic amastigotes and amastigotes in THPI macrophage cultures. In addition, compounds 1 and 2 showed antiplasmodial activity against Plasmodium falciparum D6 and W2 strains, while 2 displayed antibacterial activity against Staphylococcus aureus and methicillin-resistant S. aureus (each IC50 1.44 microg/mL). The 1H and 13C data of 1, not fully assigned previously, were unambiguously assigned using 1D and 2D NMR HMBC and HMQC experiments. In addition, the absolute stereochemistry of the isolated compounds 1 and 2 was revised as C-(3S) based on Circular Dichroism experiments. This appears to be the first report of amorphaquinone (1) and pendulone (2) from the genus Abrus.

Antiparasitic and Antimicrobial Isoflavanquinones from Abrus schimperi

The EtOH extract of Abrus schimperi (Fabaceae), collected in Kenya, demonstrated significant activity against Leishmania donovani promastigotes with IC50 value of 3.6 μg/mL. Bioassay-guided fractionation of CHCl3 fraction using Centrifugal Preparative TLC afforded two antiparasitic isoflavanquinones, namely amorphaquinone (1) and pendulone (2). They displayed IC50 values of 0.63 μg/mL and 0.43 μg/mL, respectively, against L. donovani promastigotes. Both the compounds were also evaluated against L. donovani axenic amastigotes and amastigotes in THP1 macrophage cultures. In addition, compounds 1 and 2 showed antiplasmodial activity against Plasmodium falciparum D6 and W2 strains, while 2 displayed antibacterial activity against Staphylococcus aureus and methicillin-resistant S. aureus (each IC50 1.44 μg/mL). The 1H and 13C data of 1, not fully assigned previously, were unambiguously assigned using 1D and 2D NMR HMBC and HMQC experiments. In addition, the absolute stereochemistry of the isolated compounds 1 and 2 was revised as C-(3 S) based on Circular Dichroism experiments. This appears to be the first report of amorphaquinone (1) and pendulone (2) from the genus Abrus.

Antiparasitic and antimicrobial indolizidines from the leaves of Prosopis glandulosa var. glandulosa

A new indolizidine alkaloid, named Δ¹,⁶-juliprosopine (1), together with previously known indolizidine analogs (2- 6), was isolated from the leaves of Prosopis glandulosa var. glandulosa, collected from Nevada, USA; while two other known indolizidines, juliprosopine (6) and juliprosine (7), were isolated from P. glandulosa leaves collected in Texas, USA. The structures of compound 1 and 7 were determined using a combination of NMR and MS techniques. Compound 7 exhibited potent antiplasmodial activity against Plasmodium falciparum D6 and W2 strains with IC (50) values of 170 and 150 ng/mL, respectively, while 1 was found to be less active (IC₅₀ values 560 and 600 ng/mL, respectively). Both compounds were devoid of VERO cells toxicity up to a concentration of 23 800 ng/mL. The antileishmanial activity of indolizidines was evaluated against Leishmania donovani promastigotes, axenic amastigotes, and amastigotes in THP1 macrophage cultures. When tested against macrophage cultures, the tertiary bases (1, 3, 6) were found to be more potent than quaternary salts (2, 5, 7), displaying IC₅₀ values between 0.8-1.7 µg/mL and 3.1-6.0 µg/mL, respectively. In addition, compound 7 showed potent antifungal activity against Cryptococcus neoformans and antibacterial activity against Mycobacterium intracellulare, while 1 was potent only against C. neoformans and weakly active against other organisms.

Antitumor Activity of Prosopis glandulosa Torr. on Ehrlich Ascites Carcinoma (EAC) Tumor Bearing Mice

The antitumor activity of ethanol extract of Prosopis glandulosa Torr. (EPG) was evaluated against Ehrlich ascites carcinoma (EAC) tumor model in Swiss albino mice on dose dependent manner. The activity was assessed using survival time, average increase in body weight, hematological parameters and solid tumor volume. Oral administration of EPG at the dose of 100, 200 and 400 mg/Kg, significantly (p < 0.001) increased the survival time and decreased the average body weight of the tumor bearing mice. After 14 days of inoculation, EPG was able to reverse the changes in the hematological parameters, protein and PCV consequent to tumor inoculation. Oral administration of EPG was effective in reducing solid tumor mass development induced by EAC cells. The results indicate that EPG possess significant antitumor activity on dose dependent manner.

Antimicrobial, antimalarial, and antileishmanial activities of mono- and bis-quaternary pyridinium compounds

Pyridinium-based oxime compounds have been utilized worldwide as antidotes following exposure to anticholinesterase agents. In the event of combined chemical and biological incident, it is of vital importance to know the ability of antidotes to provide additional protection against biological threats. This paper reports results of in vitro antimicrobial and antiprotozoal activities of a series of quaternary pyridinium oximes against a number of lower pathogenicity BSL-1 and 2 agents. In general, our compound panel had little to no antimicrobial action except for thiophene- and benzothiophene-substituted monoquaternary pyridinium compounds 21 and 24 that showed moderate antibacterial activity against Staphylococcus aureus and methicillin-resistant S. aureus with IC(50) values ranging from 12.2 to 17.7 μg/mL. Compounds 21 and 24 also exhibited antileishmanial activity against Leishmania donovani with IC(50) values of 19 and 18 μg/mL, respectively. Another monoquaternary pyridinium compound with a bromobutyl side chain 17 showed antimalarial activity against both a chloroquine sensitive and resistant strains of Plasmodium falciparum with IC(50) values of 3.7 and 4.0 μg/mL, respectively. None of the bisquaternary pyridinium compounds showed antimicrobial or antiprotozoal activity. None of the compounds showed cytotoxic effects toward mammalian kidney fibroblasts. Results of this study indicate that the pyridinium compounds, some of which are already in use as antidotes, do not have significant antimicrobial and antiprotozoal activities and cannot be relied upon for additional protection in the event of combined chemical-biological incident.

New α-Tetralone Galloylglucosides from the Fresh Pericarps of Juglans sigillata

Three new α-tetralone galloylglucosides (1-3), were isolated from the fresh pericarps of Juglans sigillata (Juglandaceae), together with the six known ones. The structures of the new compounds were determined as 4,6-dihydroxy-α-tetralone-4-O-[6'-O-(3″, 4″,5″-trihydroxybenzoyl)]-β-D-glucopyranoside (1), (4S)-4,5-dihydroxy-α-tetralone-4-O-[6'-O-(3″,4″,5″-trihydroxybenzoyl)]-β-D-glucopyranoside (2) and (4S)-4,5,6-tri-hydroxy-α-tetralone-4-O-[6'-O-(3″,4″,5″-trihydroxybenzoyl)]-β-D-glucopyranoside (3), respectively, on the basis of detailed spectroscopic analyses, and acidic and enzymatic hydrolysis. The antimicrobial activities of the isolated compounds (2, 4 and 7-9) were evaluated.