Synthesis and Evaluation of Antileishmanial and Cytotoxic Activity of Benzothiopyrane Derivatives.

In continuation of our efforts to identify promising antileishmanial agents based on the chroman scaffold, we synthesized several substituted 2H-thiochroman derivatives, including thiochromenes, thichromanones and hydrazones substituted in C-2 or C-3 with carbonyl or carboxyl groups. Thirty-two compounds were thus obtained, characterized, and evaluated against intracellular amastigotes of Leishmania (V) panamensis. Twelve compounds were active, with EC50 values lower than 40 µM, but only four compounds displayed the highest antileishmanial activity, with EC50 values below 10 µM; these all compounds possess a good Selectivity Index > 2.6. Although two active compounds were thiochromenes, a clear structure-activity relationship was not detected since each active compound has a different substitution pattern.

An Ethnopharmacological, Phytochemical and Pharmacological Review on Lignans from Mexican Bursera spp.

The genus Bursera belongs to the family Burseraceae and has been used in traditional Mexican medicine for treating various pathophysiological disorders. The most representative phytochemicals isolated from this genus are terpenoids and lignans. Lignans are phenolic metabolites known for their antioxidant, apoptotic, anti-cancer, anti-inflammatory, anti-bacterial, anti-viral, anti-fungal, and anti-protozoal properties. Though the genus includes more than 100 species, we have attempted to summarize the biological activities of the 34 lignans isolated from selected Mexican Bursera plants.

The Hexane Fraction of Bursera microphylla A. Gray Induces p21-Mediated Anti-Proliferative and Pro-Apoptotic Effects in Human Cancer-Derived Cell Lines.

Bursera microphylla (BM), one of the common elephant trees, is widely distributed in the Sonoran Desert in Mexico. The Seri ethnic group in the Sonoran Desert uses BM as an anti-inflammatory and painkiller drug for the treatment of sore throat, herpes labialis, abscessed tooth, and wound healing. Dried stems and leaves of BM are used in a tea to relieve painful urination and to stimulate bronchial secretion. Furthermore, BM is used for fighting venereal diseases. To investigate the effects of the hexane fraction of resin methanol extract (BM-H) on cell growth, the acute myeloid cell line (OCI-AML3) was treated with 250, 25, or 2.5 µg/mL of BM-H. The first 2 concentrations were able to significantly decrease OCI-AML3 cell number. This reduced cell number was associated with decreased S-phase, blockade of the G2/M phase of the cell cycle, and increased cell death. Similar results were obtained on all tested tumor cell lines of different origins. We found that blockade of the cell cycle was due to upregulation of p21 protein in a p53-independent way. Increase of p21 was possibly due to upstream upregulation of p-ERK (which stabilizes p21 protein) and downregulation of p-38 (which promotes its degradation). Regarding cell death, activation of caspase-3, but not of caspase-8 or -9, was detectable after BM-H treatment. In conclusion, these data suggest that the BM's hexane fraction inhibited proliferation of cell lines mainly by a p21-dependent, p53-independent mechanism and promoted apoptosis through activation of caspase-3, but not caspase-8 or -9.

New Isoflavonoids from the extract of Rhynchosia precatoria (Humb. & Bonpl. ex Willd.) DC. and their antimycobacterial activity.

ETHNOPHARMACOLOGY RELEVANCE: The evaluation of the antimycobacterial activity of extracts of medicinal plants used by Mayos against tuberculosis and respiratory problems, allowed the identification of Rhynchosia precatoria (Humb. & Bonpl. ex Willd.) DC (Fabaceae) as the best candidate to find new antimycobacterial compounds. AIM OF THE STUDY: To isolate and characterize the compounds of R. precatoria responsible for the inhibitory and bactericidal activity against Mycobacterium tuberculosis H37Rv and Mycobacterium smegmatis ATCC 700084. To determine antimycobacterial synergistic effect of pure compounds and their selectivity index towards Vero cells. MATERIALS AND METHODS: A total of six flavonoids were purified by silica gel column chromatography. Structural elucidation of the isolated compounds was achieved by using 1D and 2D NMR spectroscopy techniques. The configuration at the C-3 chiral center was established by quantum mechanical calculation of the electronic circular dichroism (ECD) spectrum. In vitro inhibitory and bactericidal activity against M. tuberculosis and M. smegmatis were determined with the redox indicator Alamar Blue (resazurin). Synergy was determined by X/Y quotient. Cytotoxicity was measured by MTT assay. RESULTS: The isolated compounds were identified as precatorin A (1), precatorin B (2), precatorin C (3), lupinifolin (4), cajanone (5) and lupinifolinol (6). Compounds 1-3 are new. Compounds 1 to 5 inhibited the growth of M. tuberculosis (MIC ≥31.25µg/mL); compounds 1, 2, 4 and 5 killed the bacteria (MBC ≥31.25µg/mL) and also inhibited M. smegmatis (MIC ≥125µg/mL), while 1 and 4 also resulted bactericidal (MBC ≥125µg/mL). Compounds 4 and 5 presented synergistic effect (X/Y quotient value <0.5) at a concentration of 1/2 MIC of each compound in the combination. Cytotoxicity in murine macrophages (RAW 264.7 cells) gave IC50 values of 13.3-46.98µM, for compounds 1-5. CONCLUSIONS: In this work we isolated two new isoflavanones (1 and 2), and one new isoflavone (3) with a weak antimycobacterial activity. The (3R) absolute configuration was assigned to 1 by computational analysis of its ECD spectrum and to 2 and 5 by similarity of their ECD spectra with that of 1. We are also reporting by first time, activity against virulent strain of M. tuberculosis for compounds 4 and 5 and their antimycobacterial synergistic effect.

General, Mild, and Metal-Free Synthesis of Phenyl Selenoesters from Anhydrides and Their Use in Peptide Synthesis.

A mild, practical, and simple procedure for phenyl selenoesters synthesis from several anhydrides and diphenyl diselenide was developed. This transition-metal-free method provides a straightforward entry to storable Fmoc-amino acid selenoesters which are effective chemoselective acylating reagents. An application to oligopeptide synthesis was illustrated.

The Hexane Fraction of Bursera microphylla A Gray Induces p21-Mediated Antiproliferative and Proapoptotic Effects in Human Cancer-Derived Cell Lines.

Bursera microphylla (BM), one of the common elephant trees, is widely distributed in the Sonoran desert in Mexico. The Seri ethnic group in the Sonoran desert uses BM as an anti-inflammatory and painkiller drug for the treatment of sore throat, herpes labialis, abscessed tooth, and wound healing. Dried stems and leaves of BM are used in a tea to relieve painful urination and to stimulate bronchial secretion. Furthermore, BM is used for fighting venereal diseases. To investigate the effects of the hexane fraction of resin methanol extract (BM-H) on cell growth, the acute myeloid cell line (OCI-AML3) was treated with 250, 25, or 2.5 µg/mL of BM-H. The first 2 concentrations were able to significantly decrease OCI-AML3 cell number. This reduced cell number was associated with decreased S-phase, blockade of G2/M phase of the cell cycle, and increased cell death. Similar results were obtained on all tested tumor cell lines of different origins. We found that blockade of the cell cycle was a result of upregulation of p21 protein in a p53-independent way. Increase of p21 was possibly a result of upstream upregulation of p-ERK (which stabilizes p21 protein) and downregulation of p-38 (which promotes its degradation). Regarding cell death, activation of caspase-3, but not of caspase-8 or -9, was detectable after BM-H treatment. In conclusion, these data suggest that BM-H inhibited proliferation of cell lines mainly by a p21-dependent, p53-independent mechanism and promoted apoptosis through activation of caspase-3 but not caspase-8 or -9.

Bromomethyllithium-mediated chemoselective homologation of disulfides to dithioacetals.

An efficient, chemoselective homologation of disulfides and diselenides to the corresponding dithio- and diselenoacetals has been developed via the addition of bromomethyllithium. Chemoselectivity is fully preserved in the presence of concomitant electrophilic sites decorating the substrates. The synthetic potential of selected dithioacetals has been evaluated in Feringa-Fañanas-Mastral-type Pd-catalyzed coupling with an organolithium and in the unusual 1,4-addition to a Weinreb amide.

Chemical Composition and Biological Activities of Fragrant Mexican Copal (Bursera spp.).

Copal is the Spanish word used to describe aromatic resins from several genera of plants. Mexican copal derives from several Bursera spp., Protium copal, some Pinus spp. (e.g., P. pseudostrobus) and a few Fabaceae spp. It has been used for centuries as incense for religious ceremonies, as a food preservative, and as a treatment for several illnesses. The aim of this review is to analyze the chemical composition and biological activity of commercial Mexican Bursera copal.

Effect of substituted stilbenes on platelet function.

Stilbenes, including resveratrol, are polyphenols provided with protective actions on the cardiovascular system. Some natural derivatives of resveratrol, like pterostilbene, have a better bioavailability than the parent compound. The aim of the present study was to prepare different substituted stilbenes (dimethylallyloxy-stilbene, dimethylallyloxy-pterostilbene) and compare them with resveratrol, p-hydroxy-stilbene and pterostilbene for their biologic activities on platelet aggregation, platelet radical oxygen species (ROS) production, and platelet nitric oxide (NO) synthesis. The results show that the increase of stilbene derivative lipophilicity enhances their biologic activities.

Diterpenoids and Triterpenoids from the Resin of Bursera microphylla and Their Cytotoxic Activity.

A chemical study of the nonpolar fraction of a methanol-soluble extract of Bursera microphylla resin yielded a variety of di- and triterpenoids. In total, 15 compounds were isolated, of which three are new, namely, malabaricatrienone (1), malabaricatrienol (2), and microphyllanin (3). The antiproliferative activity of the major compounds was evaluated in different murine cancer cell lines (M12.C3.F6 and RAW264.7) and human cancer cells (A549, HeLa, and PC-3). The new compounds (1-3) did not show significant antiproliferative activity. The known compounds ariensin (4), burseran (5), and dihydroclusin diacetate (6) were effective against the RAW264.7 cell line, with IC50 values in the micromolar range.

Efficient mechanochemical complexation of various steroid compounds with α-, ß- and γ-cyclodextrin.

Mechanochemical technology enables solvent-free micronized solid dispersions and efficient molecular host-guest inclusion complexes to be formed in matrices which contain cyclodextrins (CDs). This type of complexation has been studied using α-, ß- and γ-cyclodextrin with the dual aims of improving overall solubility and enhancing the bioavailability of common steroid compounds, such as cholic acids and ß-sitosterols or lowering cholesterol content in products of animal origin. Several parameters have been studied and optimized: CD/compound molar ratio (1:1, 1:2, 2:1 and 3:1) in function of the cavity sizes of the three different CDs, milling time (from 5 to 40 min) and rotation speed (from 100 to 300 rpm). DSC (differential scanning calorimetry) analyses have revealed that inclusion complexes were efficiently formed after 40 min milling (200 rpm) for ß-CD/cholesterol and ß-CD/ugrsodeoxycholic acid (encapsulation efficiency 96% and 77% respectively). Besides steroid encapsulation/vehiculation, the mechanochemical technique may pave the way for new ideas in solventless steroid extraction from vegetal matrices with CDs.

Antioxidant and antifungal activity of different extracts obtained from aerial parts of Inula crithmoides L.

The total phenolic content, antioxidant and antifungal activities of three Inula crithmoides extracts (n-hexane, methylene chloride and MeOH) were investigated. The methanolic extract showed the highest total phenolic content. In the DPPH assay, the methanolic and hexane extracts exhibited the highest DPPH-radical scavenging activity; in the 5-lipoxygenase assay, the hexane extract showed greater inhibitory effect with an IC50 similar to that of Trolox and ascorbic acid. The antifungal activity of the methanolic extract revealed a higher activity against Phytophtora cryptogea and Alternaria solani.

Hinokinin, an emerging bioactive lignan.

Hinokinin is a lignan isolated from several plant species that has been recently investigated in order to establish its biological activities. So far, its cytotoxicity, its anti-inflammatory and antimicrobial activities have been studied. Particularly interesting is its notable anti-trypanosomal activity.

Magnesium bis(monoperoxyphthalate) hexahydrate as mild and efficient oxidant for the synthesis of selenones.

A new, efficient and mild method for the direct oxidation of selenides to selenones using magnesium bis(monoperoxyphthalate) hexahydrate (MMPP) has been developed. Noteworthy this transformation proceeds at room temperature, employs a cheap and safety oxidant and has a broad functional group tolerance. Moreover, the produced selenones could be useful intermediates for the synthesis of different heterocyclic compounds.

One-pot heterogeneous synthesis of Δ(3)-tetrahydrocannabinol analogues and xanthenes showing differential binding to CB(1) and CB(2) receptors.

Δ(9)-tetrahydrocannabinol (Δ(9)-THC) is the major psychoactive cannabinoid in hemp (Cannabis sativa L.) and responsible for many of the pharmacological effects mediated via cannabinoid receptors. Despite being the major cannabinoid scaffold in nature, Δ(9)-THC double bond isomers remain poorly studied. The chemical scaffold of tetrahydrocannabinol can be assembled from the condensation of distinctly substituted phenols and monoterpenes. Here we explored a microwave-assisted one pot heterogeneous synthesis of Δ(3)-THC from orcinol (1a) and pulegone (2). Four Δ(3)-THC analogues and corresponding Δ(4a)-tetrahydroxanthenes (Δ(4a)-THXs) were synthesized regioselectively and showed differential binding affinities for CB1 and CB2 cannabinoid receptors. Here we report for the first time the CB1 receptor binding of Δ(3)-THC, revealing a more potent receptor binding affinity for the (S)-(-) isomer (hCB1Ki = 5 nM) compared to the (R)-(+) isomer (hCB1Ki = 29 nM). Like Δ(9)-THC, also Δ(3)-THC analogues are partial agonists at CB receptors as indicated by [(35)S]GTPγS binding assays. Interestingly, the THC structural isomers Δ(4a)-THXs showed selective binding and partial agonism at CB2 receptors, revealing a simple non-natural natural product-derived scaffold for novel CB2 ligands.

Antigenotoxic effect, composition and antioxidant activity of Dendrobium speciosum.

The chemical composition, the antiradical properties of Dendrobium speciosum (Orchidaceae) leaves and stem extracts have been studied. Furthermore, in view of the use of this orchid as "bush foods", the genotoxic/antigenotoxic effects of the extracts have been evaluated.

Conjugation of l-NAME to prenyloxycinnamic acids improves its inhibitory effects on nitric oxide production.

A series of 10 compounds resulting from the conjugation of O-prenylated naturally occurring benzoic and cinnamic acids to l-NAME were synthesized and tested together with the corresponding unprenylated parent molecule as anti-inflammatory agents for their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophages. Results indicated that the coupling between O-geranyl and O-isopentenylcinnamic acids and l-NAME led to products with an enhanced activity when compared to the parent compounds.

Furanodien-6-one from Commiphora erythraea inhibits the NF-κB signalling and attenuates LPS-induced neuroinflammation.

We investigated the in vitro anti-inflammatory activity of 1(10),4-furanodien-6-one, one the most active compounds of the hexane extract of Commiphora erythraea (Ehrenb.) Engl., by exposing microglial BV-2 cells to lipopolysaccharide. We showed that furanodien-6-one pre-treatment restored cell viability and ROS to control levels while halving NO generation. Production of pro-inflammatory IL-6, IL-23, IL-17, TGF-ß, and INF-γ, significantly induced by LPS, was also markedly reduced by furanodien-6-one treatment. We further showed that furanodien-6-one protects primary neuronal cultures against the inflammatory/toxic insults of LPS-treated BV-2 conditioned media, indicating that furanodien-6-one exerts anti-inflammatory/cytoprotective effects in neuronal cells. We then investigated whether furanodien-6-one exerts anti-inflammatory properties in an in vivo model of microglial activation. In adult mice ip-injected with LPS we found that furanodien-6-one had strong cerebral anti-inflammatory properties by inhibiting liver and brain TNFα as well as IL-1ß expression. Results were not unexpected since FTIR-metabolomic analyses showed that furanodien-6-one-treated mice had a reduced dissimilarity to control animals and that the response to LPS treatment was markedly modified by furanodien-6-one. In conclusion our data provide strong evidence of the anti-inflammatory properties of furanodien-6-one that could be exploited to counteract degenerative pathologies based on neuroinflammation.

Collinin reduces Porphyromonas gingivalis growth and collagenase activity and inhibits the lipopolysaccharide-induced macrophage inflammatory response and osteoclast differentiation and function.

BACKGROUND: Collinin is a secondary plant metabolite belonging to the class of geranyloxycoumarins. We explored the potential beneficial impact of collinin on periodontal health by investigating its effect on Porphyromonas gingivalis (P. gingivalis), lipopolysaccharide (LPS)-induced inflammatory response of macrophages, and osteoclastogenesis. METHODS: Collinin was synthesized from pyrogallol and propiolic acid. A microdilution assay was used to determine antibacterial activity of collinin. The effect of collinin on collagenase activity of P. gingivalis was determined using fluorescent collagen. Macrophages were treated with collinin before being stimulated with LPS. The secretion of interleukin-6, chemokine (C-C motif) ligand 5, and prostaglandin E2 was assessed by enzyme-linked immunosorbent assays (ELISA). The inhibitory effect of collinin on differentiation of human preosteoclastic cells was assessed by tartrate-resistant acid phosphatase staining, whereas the secretion of matrix metalloproteinase-9 (MMP-9) was measured by ELISA. Bone resorption activity was investigated by using a human bone plate coupled with an immunoassay that detected the release of collagen fragments. RESULTS: Collinin inhibited the growth of P. gingivalis. The effect was more pronounced under iron-restricted conditions. Collinin dose dependently inhibited the degradation of type I collagen by P. gingivalis. It was also a potent inhibitor of the LPS-induced inflammatory response in macrophages and completely inhibited receptor activator of nuclear factor κB ligand-dependent osteoclast differentiation and MMP-9 secretion. Last, collinin affected bone degradation mediated by mature osteoclasts by significantly decreasing the release of collagen helical peptides. CONCLUSION: Although clinical trials are required, data from these in vitro analyses support the potential of collinin as a therapeutic agent for treating inflammatory periodontitis associated with bone breakdown.

Quantitative evaluation of auraptene and umbelliferone, chemopreventive coumarins in citrus fruits, by HPLC-UV-FL-MS.

An analytical strategy, based on the development of two HPLC methods with spectrophotometric (UV), spectrofluorometric (FL), and mass spectrometric (MS) detection, has been developed to investigate the presence of and to quantitate two important chemopreventive coumarins, auraptene and umbelliferone, in foodstuffs. The analytes were determined in fruits, and fruit parts, of plants belonging to the Citrus , Poncirus , and Fortunella genera, to test their nutraceutical potential. The method validation has been carried out according to international guidelines, with good results in terms of precision (RSD < 6.9%) and extraction yields (>91%). Application to the quantitative analysis of auraptene and umbelliferone in several kinds of citrus fruits was successful, providing reliable and consistent data. Exploiting three different kinds of detection, the analytical methodology proposed herein has been demonstrated to be sound but versatile, as well as reliable. Performances and results were compared and always found in good agreement among themselves. Thus, this approach is suitable for the identification and simultaneous quantitation of auraptene and umbelliferone in citrus fruits, with the aim of evaluating their nutraceutical potential.