Antimycobacterial activities of dehydrocostus lactone and its oxidation products

Engaging Isatins and Amino Acids in Multicomponent One-Pot 1,3-Dipolar Cycloaddition Reactions-Easy Access to Structural Diversity

Multicomponent reactions (MCRs) have undoubtedly emerged as the most indispensable tool for organic chemists worldwide, finding extensive utility in the synthesis of intricate natural products, heterocyclic molecules with significant bioactivity, and pharmaceutical agents. The multicomponent one-pot 1,3-dipolar cycloaddition reactions, which were initially conceptualized by Rolf Huisgen in 1960, find extensive application in contemporary heterocyclic chemistry. In terms of green synthesis, the multicomponent 1,3-dipolar cycloaddition is highly favored owing to its numerous advantages, including high step- and atom-economies, remarkable product diversity, as well as excellent efficiency and diastereoselectivity. Among the numerous pieces of research, the most fascinating reaction involves the utilization of azomethine ylides generated from isatins and amino acids that can be captured by various dipolarophiles. This approach offers a highly efficient and convenient method for constructing spiro-pyrrolidine oxindole scaffolds, which are crucial building blocks in biologically active molecules. Consequently, this review delves deeper into the dipolarophiles utilized in the 1,3-dipolar cycloaddition of isatins and amino acids over the past six years.

Undescribed amino acid-sesquiterpene lactone adducts and sesquiterpene glycosides from the roots of Saussurea lappa and their anti-HBV activity

Saussurea lappa (Asteraceae family), a traditional Chinese medicine, has been found to possess anti-inflammatory, immune-promoting, antibacterial, antitumor, anti-HBV, cholestatic, and hepatoprotective activities. Herein, two undescribed amino acid-sesquiterpene lactone adducts, saussureamines G and H (1 and 2), and two new sesquiterpene glycosides, saussunosids F and G (3 and 4), along with 26 known sesquiterpenoids (5-30) have been isolated from the roots of S. lappa. Their structures and absolute configurations of these compounds were established by physical data analyses such as HRESIMS, IR, 1D and 2D NMR and ECD calculations. All isolated compounds were tested for anti-hepatitis B virus (anti-HBV) activity. Ten compounds (5, 6, 12, 13, 17, 19, 23, 26, 29, and 30) exhibited activities against the secretions of HBsAg and HBeAg. In particular, compound 6 showed inhibition of HBsAg and HBeAg secretion with IC50 values of 11.24 and 15.12 μM, with SI values of 1.25 and 0.93, respectively. Molecular docking studies were also conducted on the anti-HBV compounds. Overall, this study provides insights into the potential therapeutic uses of the compounds found in the roots of S. lappa, particularly in the treatment of hepatitis B virus infections.

Dehydrocostus lactone inhibits Candida albicans growth and biofilm formation

Candida albicans infections are threatening public health but there are only several antifungal drugs available. This study was to assess the effects of dehydrocostus lactone (DL) on the Candida albicans growth and biofilms Microdilution assays revealed that DL inhibits a panel of standard Candida species, including C. albicans, as well as 9 C. albicans clinical isolates. The morphological transition of C. albicans in RPMI-1640 medium and the adhesion to polystyrene surfaces can also be decreased by DL treatment, as evidenced by microscopic, metabolic activity and colony forming unit (CFU) counting assays. The XTT assay and microscopy inspection demonstrated that DL can inhibit the biofilms of C. albicans. Confocal microscopy following propidium iodide (PI) staining and DCFH-DA staining after DL treatment revealed that DL can increase the membrane permeability and intracellular reactive oxygen species (ROS) production. N-acetyl-cysteine could mitigate the inhibitory effects of DL on growth, morphological transition and biofilm formation, further confirming that ROS production induced by DL contributes to its antifungal and antibiofilm effects. This study showed that DL demonstrated antifungal and antibiofilm activity against C. albicans. The antifungal mechanisms may involve membrane damage and ROS overproduction. This study shows the potential of DL to fight Candida infections.

Dehydrocostus Lactone Suppresses Dextran Sulfate Sodium-Induced Colitis by Targeting the IKKα/β-NF-κB and Keap1-Nrf2 Signalling Pathways

Dehydrocostus lactone (DCL) is a major sesquiterpene lactone isolated from Aucklandia lappa Decne, a traditional Chinese herbal medicine that used to treat gastrointestinal diseases. This study aimed to examine the therapeutic effects of DCL on dextran sulfate sodium (DSS)-induced colitis with a focus on identifying the molecular mechanisms involved in DCL-mediated anti-inflammatory activity in macrophages. First, oral administration of DCL (5–15 mg/kg) not only ameliorated symptoms of colitis and colonic barrier injury, but also inhibited the expression of proinflammatory cytokines and myeloperoxidase in colon tissues in DSS-challenged mice. Furthermore, DCL also exhibited significant anti-inflammatory activity in LPS/IFNγ-stimulated RAW264.7 macrophages. Importantly, DCL significantly suppressed the phosphorylation and degradation of IκBα and subsequent NF-κB nuclear translocation, and enhanced the nuclear accumulation of Nrf2 in LPS/IFNγ-treated RAW264.7 cells. Mechanistically, DCL could directly interact with IKKα/β and Keap1, thereby leading to the inhibition of NF-κB signalling and the activation of Nrf2 pathway. Furthermore, DCL-mediated actions were abolished by dithiothreitol, suggesting a thiol-mediated covalent linkage between DCL and IKKα/β or Keap1. These findings demonstrated that DCL ameliorates colitis by targeting NF-κB and Nrf2 signalling, suggesting that DCL may be a promising candidate in the clinical treatment of colitis.

Aucklandiae Radix and Vladimiriae Radix: A systematic review in ethnopharmacology, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Aucklandiae Radix (AR) and Vladimiriae Radix (VR), as commonly used traditional Chinese herbal medicine, were widely used in the treatment of gastrointestinal diseases. The two herbal medicines were warm, pungent and bitter. They entered the spleen, stomach, large intestine and gallbladder meridians, and had the effect of promoting qi circulation to relieve pain. It is usually used for chest and hypochondrium, abdominal fullness and pain, tenesmus, indigestion, and warming the middle to harmonize the stomach in clinically.

AIM OF THIS REVIEW

To provide a reference for the identification of traditional use, the material basis of efficacy and preclinical research between AR and VR, this review systematically summarized the similarities and differences in ethnopharmacology, phytochemistry and modern pharmacology.

MATERIALS AND METHODS

The literature information was collected systematically from the electronic scientific databases, including PubMed, Science Direct, Google Scholar, Web of Science, Geen Medical, China National Knowledge Infrastructure, as well as other literature sources, such as classic books of herbal medicine, master's thesis, doctoral thesis.

RESULTS

In the plateau areas of Sichuan Province, VR used to be regarded as substitute or local habit for AR, which is regularly used for chest, abdominal fullness and pain, diarrhea, and other related diseases. In Chinese Pharmacopoeia (ChP) 2020 edition, 145 prescription preparations with AR were collected, such as Xianglian Wan, Muxiang Shunqi Wan, Liuwei Muxiang San. However, only one prescription preparation (Jiuxiang Zhitong Wan) contained VR. Additionally, 237 and 254 chemical components were separately isolated and identified from AR and VR, 69 kinds of compounds were common among them, and the significant differences were presented in sesquiterpene lactones, monoterpenoids, triterpenoids and phenylpropanoids. Moreover, Costunolide (COS) and Dehydrocostus lactone (DEH), two main research objects of modern pharmacology, showed multiple pharmacological activities. Not only could they inhibit the activity of some cancer cells (such as breast cancer and leukemia cells), but they regulated the levels of various inflammatory factors (including TNF-α, NF-κB, IL-1β, IL-6) and repressed the growth and reproduction of various microorganisms (like Helicobacter pylori, Staphylococcus aureus).

CONCLUSION

COS and DEH as the common active components, provide a certain basis for local medicine about the substitution of VR for AR in Sichuan province of China in the past. In addition, the sesquiterpenoids are the main common compounds in AR and VR by collecting and collating a large number of literature and various data websites. Furthermore, AR and VR have significant differences in ethnopharmacology and phytochemistry, especially in sesquiterpene lactones, monoterpenoids, triterpenoids and phenylpropanoids, and are probably viewed as reference of a separate list of AR and VR in Chinese Pharmacopoeia.

Back to the Roots-An Overview of the Chemical Composition and Bioactivity of Selected Root-Essential Oils

Since ancient times, plant roots have been widely used in traditional medicine for treating various ailments and diseases due to their beneficial effects. A large number of studies have demonstrated that-besides their aromatic properties-their biological activity can often be attributed to volatile constituents. This review provides a comprehensive overview of investigations into the chemical composition of essential oils and volatile components obtained from selected aromatic roots, including Angelica archangelica, Armoracia rusticana, Carlina sp., Chrysopogon zizanioides, Coleus forskohlii, Inula helenium, Sassafras albidum, Saussurea costus, and Valeriana officinalis. Additionally, their most important associated biological impacts are reported, such as anticarcinogenic, antimicrobial, antioxidant, pesticidal, and other miscellaneous properties. Various literature and electronic databases-including PubMed, ScienceDirect, Springer, Scopus, Google Scholar, and Wiley-were screened and data was obtained accordingly. The results indicate the promising properties of root-essential oils and their potential as a source for natural biologically active products for flavor, pharmaceutical, agricultural, and fragrance industries. However, more research is required to further establish the mechanism of action mediating these bioactivities as well as essential oil standardization because the chemical composition often strongly varies depending on external factors.

Antibacterial Activities of Echinops kebericho Mesfin Tuber Extracts and Isolation of the Most Active Compound, Dehydrocostus Lactone

Echinops kebericho Mesfin is traditionally used for the treatment of various infectious diseases. This study investigated antibacterial activity of the essential oil (EO) and the different fractions of ethanol extract. The most active component was isolated and identified. Isolation and purification was accomplished using chromatographic techniques while identification was done by spectroscopic method. Minimum inhibitory concentration (MIC) was determined using the broth micro-dilution method. In bioactive-guided isolation, percent inhibition was determined using optical density (OD) measurement. The MICs of the essential oil ranged from 78.125 μg/ml to 625 μg/ml, and its activity was observed against methicillin-resistant Staphylococcus aureus (MRSA, NCTC 12493). Ethyl acetate fraction showed high activity against MRSA (NCTC 12493), MIC = 39.075 μg/ml followed by Enterococcus faecalis (ATCC 49532), MIC = 78.125 μg/ml and was least active against Klebsiella pneumoniae (ATCC 700603), MIC = 1,250 μg/ml. MIC of hexane fraction ranged from 156.2 µg/ml to Escherichia coli (ATCC 49532) to 1,250 μg/ml to E. coli (NCTC 11954). The MICs of chloroform fraction ranged from 312.5 to 2500 μg/ml; while butanol fraction could be considered pharmacologically inactive as its MIC value was 2,500 μg/ml for all and no activity against E. coli (NCTC 11954). Dehydrocostus lactone was successfully isolated and identified whose MIC was 19.53 μg/ml against MRSA. Dehydrocostus lactone isolated from E. kebericho M. showed noteworthy antibacterial activity which lends support to ethnopharmacological use of the plant. Further optimization should be done to improve its antibacterial activities and pharmacokinetic profile.

A Review on Recent Trends in Green Synthesis of Gold Nanoparticles for Tuberculosis

Tuberculosis (TB) is a contagious disease that has affected mankind. The anti-TB treatment has been used from ancient times to control symptoms of this disease but these medications produced some serious side effects. Herbal products have been successfully used for the treatment of TB. Gold is the most biocompatible metal among all available for biomedical purposes so Gold nanoparticles (GNPs) have sought attention as an attractive biosynthesized drug to be studied in recent years for bioscience research. GNPs are used as better catalysts and due to unique small size, physical resemblance to physiological molecules, biocompatibility and non-cytotoxicity extensively used for various applications including drug and gene delivery. Greenly synthesized GNPs have much more potential in different fields because phytoconstituents used in GNP synthesis itself act as reducing and capping agents and produced more stabilized GNPs. This review is devoted to a discussion on GNPs synthesis with herbs for TB. The main focus is on the role of the natural plant bio-molecules involved in the bioreduction of metal salts during the GNPs synthesis with phytoconstituents used as antitubercular agents.

Kauniolide synthase is a P450 with unusual hydroxylation and cyclization-elimination activity

Guaianolides are an important class of sesquiterpene lactones with unique biological and pharmaceutical properties. They have been postulated to be derived from germacranolides, but for years no progress has been made in the elucidation of their biosynthesis that requires an unknown cyclization mechanism. Here we demonstrate the isolation and characterization of a cytochrome P450 from feverfew (Tanacetum parthenium), kauniolide synthase. Kauniolide synthase catalyses the formation of the guaianolide kauniolide from the germacranolide substrate costunolide. Unlike most cytochrome P450s, kauniolide synthase combines stereoselective hydroxylation of costunolide at the C3 position, with water elimination, cyclization and regioselective deprotonation. This unique mechanism of action is supported by in silico modelling and docking experiments. The full kauniolide biosynthesis pathway is reconstructed in the heterologous hosts Nicotiana benthamiana and yeast, paving the way for biotechnological production of guaianolide-type sesquiterpene lactones.

Complexation of sesquiterpene lactones with cyclodextrins: synthesis and effects on their activities on parasitic weeds

Allelochemicals are safer, more selective and more active alternatives than synthetic agrochemicals for weed control. However, the low solubility of these compounds in aqueous media limits their use as agrochemicals. Herein, we propose the application of α-, β- and γ-cyclodextrins to improve the physicochemical properties and biological activities of three sesquiterpene lactones: dehydrocostuslactone, costunolide and (-)-α-santonin. Complexation was achieved by kneading and coprecipitation methods. Aqueous solubility was increased in the range 100-4600% and the solubility-phase diagrams suggested that complex formation had been successful. The results of the PM3 semiempirical calculations were consistent with the experimental results. The activities on etiolated wheat coleoptiles, Standard Target Species and parasitic weeds were improved. Cyclodextrins preserved or enhanced the activity of the three sesquiterpene lactones. Free cyclodextrins did not show significant activity and therefore the enhancement in activity was due to complexation. These results are promising for applications in agrochemical design.

Multiplexed Thiol Reactivity Profiling for Target Discovery of Electrophilic Natural Products

Electrophilic groups, such as Michael acceptors, expoxides, are common motifs in natural products (NPs). Electrophilic NPs can act through covalent modification of cysteinyl thiols on functional proteins, and exhibit potent cytotoxicity and anti-inflammatory/cancer activities. Here we describe a new chemoproteomic strategy, termed multiplexed thiol reactivity profiling (MTRP), and its use in target discovery of electrophilic NPs. We demonstrate the utility of MTRP by identifying cellular targets of gambogic acid, an electrophilic NP that is currently under evaluation in clinical trials as anticancer agent. Moreover, MTRP enables simultaneous comparison of seven structurally diversified α,β-unsaturated γ-lactones, which provides insights into the relative proteomic reactivity and target preference of diverse structural scaffolds coupled to a common electrophilic motif and reveals various potential druggable targets with liganded cysteines. We anticipate that this new method for thiol reactivity profiling in a multiplexed manner will find broad application in redox biology and drug discovery.

Characterization of Antifungal Natural Products Isolated from Endophytic Fungi of Finger Millet (Eleusine coracana)

Finger millet is an ancient African-Indian crop that is resistant to many pathogens including the fungus, Fusarium graminearum. We previously reported the first isolation of putative fungal endophytes from finger millet and showed that the crude extracts of four strains had anti-Fusarium activity. However, active compounds were isolated from only one strain. The objectives of this study were to confirm the endophytic lifestyle of the three remaining anti-Fusarium isolates, to identify the major underlying antifungal compounds, and to initially characterize the mode(s) of action of each compound. Results of confocal microscopy and a plant disease assay were consistent with the three fungal strains behaving as endophytes. Using bio-assay guided fractionation and spectroscopic structural elucidation, three anti-Fusarium secondary metabolites were purified and characterized. These molecules were not previously reported to derive from fungi nor have antifungal activity. The purified antifungal compounds were: 5-hydroxy 2(3H)-benzofuranone, dehydrocostus lactone (guaianolide sesquiterpene lactone), and harpagoside (an iridoide glycoside). Light microscopy and vitality staining were used to visualize the in vitro interactions between each compound and Fusarium; the results suggested a mixed fungicidal/fungistatic mode of action. We conclude that finger millet possesses fungal endophytes that can synthesize anti-fungal compounds not previously reported as bio-fungicides against F. graminearum.

Sesquiterpenoids in subtribe Centaureinae (Cass.) Dumort (tribe Cardueae, Asteraceae): distribution, (13)C NMR spectral data and biological properties

Asteraceae Bercht. & J. Presl is one of the biggest and most economically important plant families. The taxonomy and phylogeny of Asteraceae is rather complex and according to the latest and most reliable taxonomic classification of Panero & Funk, based on the analysis of nine chloroplast regions, the family is divided into 12 subfamilies and 35 tribes. One of the largest tribes of Asteraceae is Cardueae Cass. with four subtribes (Carlininae, Echinopinae, Carduinae and Centaureinae) and more than 2500 species. Susanna & Garcia-Jacas have organized the genera of Centaureinae (about 800 species) into seven informal groups, which recent molecular studies have confirmed: 1. Basal genera; 2. Volutaria group; 3. Rhaponticum group; 4. Serratula group; 5. Carthamus group; 6. Crocodylium group; 7. Centaurea group. This review summarizes reports on sesquiterpenoids from the Centaureinae subtribe of the Asteraceae family, as well as the (13)C NMR spectral data described in the literature. It further reviews studies concerning the biological activities of these metabolites. For this work, literature data on sesquiterpenes from the Centaureinae subtribe were retrieved with the help of the SciFinder database and other similar data banks. All entries from 1958 until the end of 2011 were considered. This review is addressed to scientists working in the metabolomics field such as chemists, botanists, etc., the spectroscopic data reported make this work a good tool for structural elucidation, the biological section gives useful information to those who wish to study the structure activity relationships.

Sesquiterpene lactones from Lactuca canadensis and their chemotaxonomic significance

A total of 19 sesquiterpene lactones were isolated from roots of Lactuca canadensis L., of which 10 were reported for the first time from Lactuca species and two were unknown. This is also the first report on the co-occurrence of three pairs of zaluzanin C-type guaianolides, epimeric at C-3, and on the presence of six eudesmanolides, oxygenated at C-1 and C-3, in Lactuca species. The new compounds were characterized as 3-epizaluzanin C-3-O-β-glucopyranoside and 11,13-dehydrolactuside C using 1D and 2D NMR and high resolution mass spectroscopy. The sesquiterpene lactone profile of this species is dominated by zaluzanin C-type guaianolides (9 compounds) and eudesmanolides (8 compounds). The dissimilarity of this profile compared to that of other taxa of the genus is discussed.

Antimycobacterial agents from selected Mexican medicinal plants

As part of the ICBG program Bioactive Agents from Dryland Biodiversity of Latin America, the present investigation was undertaken to explore the possible antimycobacterial potential of compounds derived from selected Mexican medicinal plants. Bioassay-guided fractionation of the crude extracts of Rumex hymenosepalus (Polygonaceae), Larrea divaricata (Zygophyllaceae), Phoradendron robinsonii (Loranthaceae) and Amphipteryngium adstringens (Julianiaceae) led to the isolation of several antimycobacterial compounds. Four stilbenoids, two flavan-3-ols and three anthraquinones were isolated from R. hymenosepalus. Two flavonols and nordihydroguaiaretic acid were obtained from L. divaricata. Sakuranetin was the antimycobacterial agent isolated from P. robinsonii. Two known triterpenoids and the novel natural product 3-dodecyl-1,8-dihydroxy-2-naphthoic acid were obtained from A. adstringens. In general, the isolates were identified by spectral means. The antimycobacterial activity of the secondary compounds isolated from the analysed species, as well as that of nine pure compounds previously isolated in our laboratories, was investigated; the MIC values ranged from 16 to 128μ mL−1. Among the tested compounds, the glycolipids, sesquiterpenoids and triterpenoids showed the best antimycobacterial activity. The antimycobacterial property of the glycolipids is reported for the first time. Although the tested compounds showed moderate antimycobacterial activity, their presence in the analysed species provides the rationale for their traditional use in the treatment of tuberculosis.

Stereoselective hydrogenation on the exocyclic and conjugated double bond of sesquiterpene lactones by Aspergillus versicolor D-1

Aspergillus versicolor D-1 was employed to convert dehydrocostuslactone (1) and 3-hydroxy-1(10),3,11(13)-guaiatriene-12,6-olide-2-one (5) stereoselectively. The reactions occurring were specific hydrogenation on the exocyclic alpha,beta-double bond of sesquiterpene lactones with excellent conversion. Products were identified by the analysis of their spectra such as UV, IR, MS, (1)H, (13)C NMR, and NOESY, and the structure of one new compound was elucidated. The characteristic of the stereoselective hydrogenation was also discussed and suggested.

Indian medicinal plants as a source of antimycobacterial agents

It is estimated that one-third of the world's population is infected with tubercle bacillus and the problem of tuberculosis (TB) has been intensified due to HIV pandemic providing a large reservoir of highly susceptible individuals. Since no anti-TB drugs have been introduced in past 30 years, there is an urgent need to search for and develop new, effective and affordable anti-TB drugs. In this scenario, the plant kingdom with enormous chemical diversity may be looked as an important source of new anti-TB agents. Of 17,500 higher plant species occurring in India only about 365 species have been evaluated so far for antimycobacterial activity. The present review article describes the 255 (70% of 365) plant species from a wide range of families that have shown antimycobacterial activity. The species are enumerated in table format describing plant species and family, plant part used, type of extract and in vitro activity (MIC value), information on active compounds, if any, and uses in the ethnomedicine and Ayurveda. Interestingly, most of the plant species have shown strong positive ethnopharmacological correlation with the traditional knowledge. In addition, the recent in vitro screening methods for antimycobacterial activity are also described in brief. An attempt has been made to highlight the promising plant species for further investigation as leads for drug development.

Synergistic antimycobacterial activities of sesquiterpene lactones from Laurus spp

OBJECTIVES

The aim of this study was to determine the antimycobacterial potential of laurel oil, its fractions and its two sesquiterpene lactones against several mycobacterial strains and clinical isolates, and to establish the possibility of occurrence of some synergistic effects between those lactones using a modification of the fluorometric Alamar Blue microassay (FMABA).

METHODS

The in vitro antimycobacterial activity of whole oil and its fractions and pure active compounds were determined by FMABA. A bioassay-guided fractionation of the traditional preparation of laurel oil from Madeira Islands was performed, yielding pure compounds chemically identified by standard procedures. Synergism of pure compounds was established by X/Y quotient analysis adapted to FMABA.

RESULTS

Sesquiterpene lactones, costunolide and dehydrocostuslactone, were the compounds responsible for the antimycobacterial activity against Mycobacterium tuberculosis H37Rv with MICs of 6.25 and 12.5 mg/L, respectively. Antimycobacterial activity against drug-resistant M. tuberculosis clinical isolates was better for the mixture than for pure compounds.

CONCLUSIONS

Both lactones presented synergistic activity, i.e. analysis of relative fluorescence units presented an X/Y value <0.5 at a concentration of 1/8 MIC of each compound in the combination. Establishment of synergism by FMABA represents another application of the microplate Alamar Blue assay.

Origin and Chemical Variation of Brazilian Propolis

Propolis is a hive product containing chiefly beeswax and plant-derived substances such as resin and volatile compounds. Propolis has been used as an antiseptic and wound healer since ancient times and interest for the product has increased recently. Probably few plant species contribute as major resin sources. Green propolis derives mainly from vegetative apices of Baccharis dracunculifolia (alecrim plants). However, wide variation detected in the chemical composition suggests contributions from alternative resin plant sources. Predominant components of the resin of green propolis are cinnamic acids, chiefly compounds bearing prenyl groups. Terpenoid compounds, such as sesqui, di and pentacyclic triterpenoids, have been detected in many, but not all, samples investigated. Propolis research has uncovered potentialities of substances previously isolated from plants and has detected constituents of plant origin that would hardly be known otherwise.

Plant Origin of Green Propolis: Bee Behavior, Plant Anatomy and Chemistry

Propolis, a honeybee product, has gained popularity as a food and alternative medicine. Its constituents have been shown to exert pharmacological effects, such as anti-microbial, anti-inflammatory and anticancer. Shoot apices of Baccharis dracunculifolia (alecrim plant, Asteraceae) have been pointed out as sources of resin for green propolis. The present work aimed (i) to observe the collecting behavior of bees, (ii) to test the efficacy of histological analysis in studies of propolis botanical origin and (iii) to compare the chemistries of alecrim apices, resin masses and green propolis. Bee behavior was observed, and resin and propolis were microscopically analyzed by inclusion in methacrylate. Ethanol extracts of shoot apices, resin and propolis were analyzed by gas chromatography/mass spectroscopy. Bees cut small fragments from alecrim apices, manipulate and place the resulting mass in the corbiculae. Fragments were detected in propolis and identified as alecrim vestiges by detection of alecrim structures. Prenylated and non-prenylated phenylpropanoids, terpenoids and compounds from other classes were identified. Compounds so far unreported for propolis were identified, including anthracene derivatives. Some compounds were found in propolis and resin mass, but not in shoot apices. Differences were detected between male and female apices and, among apices, resin and propolis. Alecrim apices are resin sources for green propolis. Chemical composition of alecrim apices seems to vary independently of season and phenology. Probably, green propolis composition is more complex and unpredictable than previously assumed.

Cytotoxic sesquiterpene lactones from the root of Saussurea lappa

Bioassay-directed fractionation of Saussurea lappa led to the isolation of a novel lappadilactone (1) and seven sesquiterpene lactones (2-8) as cytotoxic principles against selected human cancer cell lines. Lappadilactone (1), dehydrocostuslactone (2), and costunolide (5) exhibited the most potent cytotoxicity with CD50 values in the range 1.6-3.5 microg/mL in dose- and time-dependent manners. The cytotoxicities were not specific and showed similar activities against HepG2, OVCAR-3 and HeLa cell lines. The structure-activity relationship showed that the alpha-methylene-gamma-lactone moiety is necessary for cytotoxicity, and activity is reduced with the presence of a hydroxyl group. In addition, seven noncytotoxic compounds (9-15) were also isolated, including two novel sesquiterpenes, a guaianolide-type with a C17 skeleton, lappalone (13), and 1beta,6alpha-dihydroxycostic acid ethyl ester (14). The structures of the new compounds were elucidated from spectroscopic and/or X-ray data interpretations. Some representative compounds were also tested for antibacterial activity; however, only marginal activities were observed. Therefore, compounds 1-8 are potential cytotoxic agents but without significant antibacterial effect.

Antimycobacterial evaluation of Peruvian plants

We present the results of an antimycobacterial screening of 270 Peruvian plant samples representing 216 species from 171 genera in 63 families. Dichloromethane extracts were tested at a concentration of 50 microg/ml for inhibition of Mycobacterium tuberculosis in radiometric culture. Slightly more than half of the samples tested showed inhibition of M. tuberculosis at this concentration.

A review of antimycobacterial natural products

Tuberculosis is a chronic infectious disease caused by several species of mycobacteria. Due to multi-drug resistant strains of mycobacteria and to a high prevalence of tuberculosis in patients who have acquired human immunodeficiency syndrome (AIDS), the number of patients infected with the disease is increasing worldwide. Thus there is an urgent need for new effective antimycobacterial agents to replace those currently in use. In this instance, the plant kingdom is undoubtedly a valuable source for new anti-tuberculosis agents. The present review article reports the findings from an extensive literature search of all plants that have been assessed for antimycobacterial/antitubercular activity over the past 20-30 years. An attempt has been made to summarize the information in order to highlight those promising plant species which are worthy of further investigation as leads for drug development. Over 350 plant species from a wide range of families and origins, containing various chemical classes of compounds, have been screened for such activity. A review of the relevant in vitro assays using different species of pathogenic and non-pathogenic mycobacteria is also included.

Antitubercular activity of pentacyclic triterpenoids from plants of Argentina and Chile

Screening of plants from South America for antitubercular activity and subsequent assay-guided fractionation resulted in the isolation and characterization of several pentacyclic triterpenoids. The MIC values of 22 triterpenoids were determined using the radiorespiratory BACTEC assay and range from 8 microM to above 128 microM. The structure-activity relationships are discussed.