The cytotoxic and embryotoxic effects of kaurenoic acid, a diterpene isolated from Copaifera langsdorffii oleo-resin

Anticancer diterpenes of African natural products: Mechanistic pathways and preclinical developments

BACKGROUND

The African continent is home to five biodiversity hotspots, boasting an immense wealth of medicinal flora, fungi and marine life. Diterpenes extracted from such natural products have compelling cytotoxic activities that warrant further exploration for the drug market, particularly in cancer therapy, where mortality rates remain elevated worldwide.

PURPOSE

To demonstrate the potential of African natural products on the global stage for cancer therapy development and provide an in-depth analysis of the current literature on the activity of cancer cytotoxic diterpenes from African natural sources (to our knowledge, the first of its kind); not only to reveal the most promising candidates for clinical development, but to demonstrate the importance of preserving the threatened ecosystems of Africa.

METHODS

A comprehensive search by means of the PRISMA strategy was conducted using electronic databases, namely Web of Science, PubMed, Google Scholar and ScienceDirect. The search terms employed were 'diterpene & mechanism & cancer' and 'diterpene & clinical & cancer'. The selection process involved assessing titles in English, Portuguese and Spanish, adhering to predefined eligibility criteria. The timeframe for inclusion spanned from 2010 to 2023, resulting in 218 relevant papers. Chemical structures were visualized using ChemDraw 21.0, PubChem was utilized to search for CID numbers.

RESULTS

Despite being one of the richest biodiverse zones in the world, African natural products are proportionally underreported compared to Asian countries or otherwise. The diterpenes andrographolide (Andrographis paniculata), forskolin (Coleus forskohlii), ent-kauranes from Isodon spp., euphosorophane A (Euphorbia sororia), cafestol & kahweol (Coffea spp.), macrocylic jolkinol D derivatives (Euphorbia piscatoria) and cyathane erinacine A (Hericium erinaceus) illustrated the most encouraging data for further cancer therapy exploration and development.

CONCLUSIONS

Diterpenes from African natural products have the potential to be economically significant active pharmaceutical and medicinal ingredients, specifically focussed on anticancer therapeutics.

Toxicological Effects of Copaiba Oil (Copaifera spp.) and Its Active Components

Vegetable oils are among the most important traditional resources of Amazonia. Oleoresins are a type of oil that have interesting characteristics and highly bioactive properties with pharmacological potential. Oleoresins produced in the trunks of Copaifera (Fabaceae) spp. trees, known as copaiba oils, are made up of terpenes from the sesquiterpene (volatile) and diterpene (resinous) classes, but in amounts that vary between species and depending on several factors, such as soil type. Despite being used for medicinal purposes, via topical and oral application, the toxic effects of copaiba oils and their constituents are little known. The current paper reviews the toxicological studies, both in vitro and in vivo, described in the literature for copaiba oils, as well as the cytotoxic characteristics (against microorganisms and tumor cells) in in silico, in vitro and in vivo models for the sesquiterpenes and diterpenes that make up these oils.

Kaurenoic Acid Reduces Ongoing Chronic Constriction Injury-Induced Neuropathic Pain: Nitric Oxide Silencing of Dorsal Root Ganglia Neurons

Kaurenoic acid (KA) is a diterpene extracted from Sphagneticola trilobata (L.) Pruski. KA presents analgesic properties. However, the analgesic activity and mechanisms of action of KA in neuropathic pain have not been investigated so far; thus, we addressed these points in the present study. A mouse model of neuropathic pain was induced by chronic constriction injury (CCI) of the sciatic nerve. Acute (at the 7th-day post-CCI surgery) and prolonged (from 7–14th days post-CCI surgery) KA post-treatment inhibited CCI-induced mechanical hyperalgesia at all evaluated time points, as per the electronic version of von Frey filaments. The underlying mechanism of KA was dependent on activating the NO/cGMP/PKG/ATP-sensitive potassium channel signaling pathway since L-NAME, ODQ, KT5823, and glibenclamide abolished KA analgesia. KA reduced the activation of primary afferent sensory neurons, as observed by a reduction in CCI-triggered colocalization of pNF-κB and NeuN in DRG neurons. KA treatment also increased the expression of neuronal nitric oxide synthase (nNOS) at the protein level as well as the intracellular levels of NO in DRG neurons. Therefore, our results provide evidence that KA inhibits CCI neuropathic pain by activating a neuronal analgesic mechanism that depends on nNOS production of NO to silence the nociceptive signaling that generates analgesia.

Kaurenoic acid nanocarriers regulates cytokine production and inhibit breast cancer cell migration

Breast cancer is the type of cancer with the highest incidence in women around the world. Noteworthy, the triple-negative subtype affects 20% of the patients while presenting the highest death rate among subtypes. This is due to its aggressive phenotype and the capability of invading other tissues. In general, tumor-associated macrophages (TAM) and other immune cells, are responsible for maintaining a favorable tumor microenvironment for inflammation and metastasis by secreting several mediators such as pro-inflammatory cytokines IL-1β, IL-6, and TNF-α, chemokines like CCL2, and other proteins, as metalloproteinases of matrix (MMP). On the other hand, immunomodulatory agents can interfere in the immune response of TAM and change the disease prognosis. In this work, we prepared nanostructured lipid carriers containing kaurenoic acid (NLC-KA) to evaluate the effect on cytokine production in vitro of bone marrow-derived macrophages (BMDM) and the migratory process of 4 T1 breast cancer cells. NLC-KA prepared from a blend of natural lipids was shown to have approximately 90 nm in diameter with low polydispersity index. To test the effect on cytokine production in vitro in NLC-KA treated BMDM, ELISA assay was performed and pro-inflammatory cytokines IL-1β, IL-6, and TNF-α were quantified. The formulation reduced the secretion of IL-1β and TNF-α cytokines while presenting no hemolytic activity. Noteworthy, an anti-migratory effect in 4 T1 breast cancer cells treated with NLC-KA was observed in scratch assays. Further, MMP9 and CCL2 gene expressions in both BMDM and 4 T1 treated cells confirmed that the mechanism of inhibition of migration is related to the blockade of this pathway by KA. Finally, cell invasion assays confirmed that NLC-KA treatment resulted in less invasiveness of 4 T1 cells than control, and it is independent of CCL2 stimulus or BMDM direct stimulus. Ultimately, NLC-KA was able to regulate the cytokine production in vitro and reduce the migration of 4 T1 breast cancer cells by decreasing MMP9 gene expression.

The predominance of Shiga toxin-producing E. coli in the Southeast Coast of India

In this study, we reported Shiga toxin-producing Escherichia coli (STEC) in 847 samples, including those in coastal waters, sediments, and fish samples in the Southeast Coast of India. A total of 3742 E. coli strains were identified using conventional and molecular identification methods. Of these, 1518 isolates expressed virulent genes Stx1, Stx2, and Eae; effects on these genes on toxicity were examined. Furthermore, 2224 non-STEC isolates caused hemolytic uremic syndrome and played a key role in the persistence of STEC contamination. We conclude that toxin production is not adequate to cause disease, and the pathogenic mechanism of STEC remains poorly defined. Therefore, the present study indicates the status of pollution, highlighting the need for sanitation in public health.

The diterpene from Sphagneticola trilobata (L.) Pruski, kaurenoic acid, reduces lipopolysaccharide-induced peritonitis and pain in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Sphagneticola trilobata (L.) Pruski is a plant species belonging to the Asteraceae family. Kaurenoid acid (KA) is a diterpene metabolite and one of the active ingredients of Sphagneticola trilobata (L.) Pruski. Extracts containing KA are used in traditional medicine to treat pain, inflammation, and infection.

AIM

The goal of the present study was to investigate the in vivo effects of KA (1-10 mg/kg, per oral gavage) upon LPS inoculation in mice by intraperitoneal (i.p.) or intraplantar (i.pl.; subcutaneous plantar injection) routes at the dose of 200 ng (200 μL or 25 μL, respectively).

METHODS

In LPS paw inflammation, mechanical and thermal hyperalgesia MPO activity and oxidative imbalance (TBARS, GSH, ABTS and FRAP assays) were evaluated. In LPS peritonitis we evaluated leukocyte migration, cytokine production, oxidative stress, and NF-κB activation.

RESULTS

KA inhibited LPS-induced mechanical and thermal hyperalgesia, MPO activity and modulated redox status in the mice paw. Pre- and post-treatment with KA inhibited migration of neutrophils and monocytes in LPS peritonitis. KA inhibited the pro-inflammatory/hyperalgesic cytokine (e.g., TNF-α, IL-1β and IL-33) production while enhanced anti-inflammatory/analgesic cytokine IL-10 in peritoneal cavity. In agreement with the effect of KA over pro-inflammatory cytokines it inhibited oxidative stress (total ROS, superoxide production and superoxide positive cells) and NF-κB activation during peritonitis.

CONCLUSION

KA efficiently dampens LPS-induced peritonitis and hyperalgesia in vivo, suggesting it as a suitable candidate to control excessive inflammation and pain during gram-negative bacterial infections and bringing mechanistic explanation to the ethnopharmacological application of Sphagneticola trilobata (L.) Pruski in inflammation and infection.

Molecular events and cytotoxic effects of a novel thiosemicarbazone derivative in human leukemia and lymphoma cell lines

The present study aimed to investigate the cytotoxic effect of 38 new thiosemicarbazone derivatives on hematological neoplastic cells lines and to select the most effective compounds to investigate the main molecular mechanisms involved in cell death. Cytotoxicity screening on Daudi and Jurkat cells revealed that only compound 1b met the selection criteria; therefore, it was chosen for further investigation. Cell viability of Daudi, Jurkat, Molt-4, Namalwa, K562, and MM.1S cell lines decreased in a concentration- and time-dependent manner after compound1b incubation; nevertheless the compound neither caused significant hemolysis nor reduction in peripheral blood mononuclear cell viability. Although no changes were observed on cell cycle or Ki-67 expression, compound1b induced apoptotic-like cell death with mitochondrial involvement, Bax/Bcl-2 inversion, AIF release, survivin inhibition, and caspase-3 activation in both Daudi and Jurkat cells. Furthermore, the compound reduced NFκB expression in Jurkat cells. In Daudi cells, compound1b also decreased CHOP, Akt, pAkt, and MAPK/ERK2 expression, thereby suggesting modulation of UPR, PI3K/Akt/mTOR, and MAPK/ERK signaling pathways. Finally, the compound was able to reduce the cell viability of samples collected from patients with different lymphoid neoplasms subtypes, showing that thiosemicarbazones derivatives could be used in the development of new drugs with anticancer activity.

p-Methoxycinnamic Acid Diesters Lower Dyslipidemia, Liver Oxidative Stress and Toxicity in High-Fat Diet Fed Mice and Human Peripheral Blood Lymphocytes

The pursuit of cholesterol lowering natural products with less side effects is needed for controlling dyslipidemia and reducing the increasing toll of cardiovascular diseases that are associated with morbidity and mortality worldwide. The present study aimed at the examining effects of p-methoxycinnamic acid diesters (PCO-C) from carnauba (Copernicia prunifera)-derived wax on cytotoxic, genotoxic responses in vitro and on dyslipidemia and liver oxidative stress in vivo, utilizing high-fat diet (HFD) chronically fed Swiss mice. In addition, we evaluated the effect of PCO-C on the expression of key cholesterol metabolism-related genes, as well as the structural interactions between PCO-C and lecithin-cholesterol acyl transferase (LCAT) in silico. Oral treatment with PCO-C was able to reduce total serum cholesterol and low-density lipoprotein (LDL) levels following HFD. In addition, PCO-C reduced excessive weight gain and lipid peroxidation, and increased the gene expression of LCAT following HFD. Furthermore, the high affinity of the studied compound (ΔG: −8.78 Kcal/mol) towards the active sites of mutant LCAT owing to hydrophobic and van der Waals interactions was confirmed using bioinformatics. PCO-C showed no evidence of renal and hepatic toxicity, unlike simvastatin, that elevated aspartate aminotransferase (AST) levels, a marker of liver dysfunction. Finally, PCO-C showed no cytotoxicity or genotoxicity towards human peripheral blood lymphocytes in vitro. Our results suggest that PCO-C exerts hypocholesterolemic effects. The safety of PCO-C in the toxicological tests performed and the reports of its beneficial biological effects render this a promising compound for the development of new cholesterol-lowering therapeutics to control dyslipidemia. More work is needed for further elucidating PCO-C role on lipid metabolism to support future clinical studies.

5-Nitro-Thiophene-Thiosemicarbazone Derivatives Present Antitumor Activity Mediated by Apoptosis and DNA Intercalation

BACKGROUND

Considering the need for the development of new antitumor drugs, associated with the great antitumor potential of thiophene and thiosemicarbazonic derivatives, in this work we promote molecular hybridization approach to synthesize new compounds with increased anticancer activity.

OBJECTIVE

Investigate the antitumor activity and their likely mechanisms of action of a series of N-substituted 2-(5-nitro-thiophene)-thiosemicarbazone derivatives.

METHODS

Methods were performed in vitro (cytotoxicity, cell cycle progression, morphological analysis, mitochondrial membrane potential evaluation and topoisomerase assay), spectroscopic (DNA interaction studies), and in silico studies (docking and molecular modelling).

RESULTS

Most of the compounds presented significant inhibitory activity; the NCIH-292 cell line was the most resistant, and the HL-60 cell line was the most sensitive. The most promising compound was LNN-05 with IC50 values ranging from 0.5 to 1.9 µg.mL-1. The in vitro studies revealed that LNN-05 was able to depolarize (dose-dependently) the mitochondrial membrane, induceG1 phase cell cycle arrest noticeably, promote morphological cell changes associated with apoptosis in chronic human myelocytic leukaemia (K-562) cells, and presented no topoisomerase II inhibition. Spectroscopic UV-vis and molecular fluorescence studies showed that LNN compounds interact with ctDNA forming supramolecular complexes. Intercalation between nitrogenous bases was revealed through KI quenching and competitive ethidium bromide assays. Docking and Molecular Dynamics suggested that 5-nitro-thiophene-thiosemicarbazone compounds interact against the larger DNA groove, and corroborating the spectroscopic results, may assume an intercalating interaction mode.

CONCLUSION

Our findings highlight 5-nitro-thiophene-thiosemicarbazone derivatives, especially LNN-05, as a promising new class of compounds for further studies to provide new anticancer therapies.

Biological activity of Morita-Baylis-Hillman adduct homodimers in L. infantum and L. amazonensis: anti-Leishmania activity and cytotoxicity

This study is a report on the anti-Leishmania activity of Morita-Baylis-Hillman (MBH) homodimers adducts against the promastigote and axenic amastigote forms of Leishmania (Leishmania) infantum and Leishmania (Leishmania) amazonensis and on the cytotoxicity of these adducts to human blood cells. Both studied homodimers, MBH 1 and MBH 2, showed activity against the promastigote forms of L. infantum and L. amazonensis, which are responsible for visceral and cutaneous leishmaniasis, respectively. Additionally, the homodimers presented biological activity against the axenic amastigote forms of these two Leishmania species. The adducts exhibited no hemolytic activity to human peripheral blood mononuclear cells or erythrocytes at the tested concentrations and achieved higher selectivity indices than amphotericin B. Evaluation of cell death by apoptosis revealed that the homodimers had better apoptosis/necrosis profiles than amphotericin B in the promastigote forms of both L. infantum and L. amazonensis. In conclusion, these Morita-Baylis-Hillman adducts had anti-Leishmania activity in an in vitro model and may thus be promising molecules in the search for new drugs to treat leishmaniasis.

Antimicrobial and cytotoxic effects of the Copaifera reticulata oleoresin and its main diterpene acids

ETHNOPHARMACOLOGICAL RELEVANCE

The oleoresin of Brazilian Copaifera reticulata is a traditional remedy used for the treatment of skin and urinary tract infections, respiratory diseases, rheumatism, ulcer and tumours; thus, playing an important role in the primary health care of the indigenous population.

AIM

As most previous pharmacological tests used the crude oleoresin and only a few studies so far dealt with enriched fractions or pure chemically defined compounds, the aim of this study was to systematically evaluate the antimicrobial and cytotoxic properties of the Copaifera reticulata oleoresin and to assign traditional uses to specific secondary metabolites.

MATERIALS AND METHODS

The oleoresin, as well as its neutral and acidic fractions were tested for their activity against six cancer cell lines, two clinically relevant bacterial strains, and two dermatophytes. Both fractions were analysed by GC-MS and UHPLC-ELSD, respectively. The antibacterial acidic phase was further fractionated by preparative chromatography to purify and characterize the compounds responsible for the observed pharmacological effect.

RESULTS

Whereas no cytotoxic activity was detected, the crude oleoresin and its acidic fraction showed antibacterial activity against gram-positive bacteria Enterococcus faecium (IC₅₀ values 4.2 and 4.8 µg/mL, respectively) and methicillin-resistant Staphylococcus aureus (MRSA, IC₅₀ values 5.3 and 7.2 µg/mL, respectively). Purification of the acidic fraction of the C. reticulata oleoresin yielded two dicarboxylic diterpene acids and the four main diterpene acids, comprising three different diterpene scaffolds. Interestingly, the activity was not restricted to a particular diterpene-type but rather depended on the compounds' lipophilicity, with the most active constituent showing IC₅₀ values of 1.6 (E. faecium) and 2.5 µg/mL (MRSA), respectively. Furthermore, ent-polyalthic acid, the major diterpenoid, was significantly active against dermatophytes with IC₅₀ values of 6.8 µg/mL (Trichophyton rubrum) and 4.3 µg/mL against (T. mentagrophytes).

CONCLUSION

The present study proved the antimicrobial effects of the C. reticulata oleoresin and its diterpenoid constituents, confirming its wide use in folk medicine for the treatment of skin and urinary tract infections. The inhibitory activity of copaiba diterpenoids against dermatophytic fungi as well as the gram-positive bacteria E. faecium and MRSA is being reported for the first time, providing potential lead structures for the treatment of these clinically relevant bacterial strains.

Virulence factors of Candida species from the oral mucosa and prostheses of elderly people from a riverside community in the Amazon state, Brazil

Abstract Introduction Candida albicans is the yeast most commonly affecting the oral cavity, sometimes causing infection. However, several factors may be associated with the onset of candidiasis, which may be related not only to the hygiene and health of individuals, but also to the pathogenicity of these microorganisms. Objective To evaluate the virulence factors of Candida yeasts isolated from the oral mucosa of elderly people living in the “Comunidade Lago do Limão”, municipality of Iranduba, Amazonas state, Brazil. Material and method Testes were performed to assess the production of urease, proteinase, phospholipase and hemolysin. Statistical analysis used the Fisher's exact test and the Chi-squared test. Result Prevalence of non-albicans species was observed. As for virulence factors, all isolates were negative ureases, and there was prevalence of very strong proteinase production, whereas most isolates did not produce this enzyme in the phospholipase test. All yeasts analyzed presented hemolysin production, with grade IV hemolysis as the most prevalent. There was no statistically significant difference between the virulence of isolates from the oral cavity and the prostheses of the elderly analyzed. Conclusion Several virulence factors may present with high intensity in the presence of oral microbiota changes. In addition, non-albicans species present number of virulence factors similar to that of C. albicans, with high pathogenicity. This study allows a better analysis of candidiasis prevention strategies aiming to promote improvement in the health and quality of life for the elderly.

In vitro cytotoxicity and structure-activity relationship approaches of ent-kaurenoic acid derivatives against human breast carcinoma cell line

In this study, ent-kaurenoic acid derivatives were obtained by microbial transformation methodologies and tested against breast cancer cell lines (MCF-7). A multivariate quantitative-structure activity relationship (QSAR) analysis was performed taking into account both microbial transformation derivatives and other analogues previously reported in literature to give some insight into the main features behind the cytotoxic activity displayed by kaurane-type diterpenes against MCF-7 cells. The partial least square regression (PLS) method was employed in the training set and the best PLS model was built with a factor describing 69.92% of variance and three descriptors (logP, ε_HOMO and ε_HOMO-1) selected by the Ordered Predictors Selection (OPS) algorithm. The QSAR model provided reasonable regression (Q² = 0.64, R² = 0.72, SEC = 0.29 and SEV = 0.33). The model was validated by leave-N-out cross-validation, y-randomization and external validation (R²_pred = 0.89 and SEP = 0.27). The selected descriptors indicated that the activity was mainly related to electronic parameters (HOMO and HOMO-1 molecular orbital energies), as well as to logP. These findings suggest that higher activity values are directly related with both higher logP and frontier orbital energy values. The positive relationship between these orbitals and the activity suggests that the ent-kaurenoic acid analogues interaction with the target involves charge displacement, which is entirely consistent with the literature. Based on these findings, three compounds were proposed and one of them was synthesized and tested. The experimental result confirmed the activity predicted by the model.

Pharmacokinetic Profile of Kaurenoic Acid after Oral Administration of Araliae Continentalis Radix Extract Powder to Humans

The objective of this study was to characterize pharmacokinetics (PKs) of kaurenoic acid (KAU) after administration of the clinical usual dose of Araliae Continentalis Radix extract powder to Korean subjects for the first time and evaluate the mechanism of its absorption in vitro. A simple, sensitive, and selective analytical method was developed for the detection of KAU in human plasma. Concentrations of KAU were quantified by ultra-performance liquid chromatography tandem mass spectrometry after simple liquid–liquid extraction. This pharmacokinetic model of KAU was best described by a two-compartment model with first-order absorption. To identify efflux transporters involved in the absorption of KAU, a Caco-2 monolayer model was used. Estimated PK parameters were: systemic clearance, 23.89 L/h; inter-compartmental clearance, 15.55 L/h; rate constant for absorption, 1.72 h⁻¹; volume of distribution of the central compartment, 24.44 L; and volume of distribution of the peripheral compartment, 64.05 L. Results from Caco-2 bidirectional transport study suggested that KAU was a potential substrate of efflux transporters. In summary, PKs of KAU were successfully characterized after administration of a usual dose of Araliae continentalis Radix extract powder in human with the newly developed bioanalytical method and the mechanism of absorption of KAU was identified clearly.

Occurrence, chemical composition, biological activities and analytical methods on Copaifera genus-A review

Copaifera is a genus of large trees found in Brazil, mainly in Amazon forest, but also in Atlantic forest and cerrado biomes. It has also been found in other countries in South America. In Africa, it is found mainly in Congo, Cameroon, Guinea and Angola. Its oleoresin has been used in folk medicine in the treatment of numerous healthy disorders, such as urinary, respiratory, skin and inflammatory diseases, for which there are several studies corroborating its ethnopharmacological uses. It is also extensively employed in the pharmaceutical and cosmetic industries in the development of ointments, pills, soaps, perfumes, among others. Copaifera oleoresin contains mainly diterpenes, such as: kaurenoic acid, kaurenol, copalic acid, agathic acid, hardwiickic acid, polyalthic acid, and sesquiterpenes, comprising β-caryophyllene, caryophyllene oxide, α-copaene, α-humulene, γ-muurolene and β-bisabolol, among other compounds. On the other hand, Copaifera leaves contain mainly phenolic compounds, such as flavonoids and methylated galloylquinic acid derivatives. Therefore, considering the economic importance of Copaifera oleoresin, its ethnopharmacological uses, the need to develop new pharmaceuticals for the treatment of many diseases, as well as the pharmacological potential of the compounds found in Copaifera spp., it was undertaken a review covering mostly the last two decades on the distribution, chemistry, pharmacology, quality control and safety of Copaifera species.

Ethnomedicinal, phytochemical and pharmacological profile of a mangrove plant Ceriops Decandra GriffDin Hou

Ceriops decandra is a mangrove tree species, reputed for its folkloric uses in the treatment of gastrointestinal disorders, infection, snakebites, inflammation, and cancer. Different parts of the plant are rich with various phytoconstituents which include diterpenoids (ceriopsin A-G), triterpenoids (lupeol, α-amyrin, oleanolic acid, ursolic acid), and phenolics (catechin, procyanidins).These phytoconstituents and their derivatives could form a new basis for developing new drugs against various diseases. The objective of the present study is to compile the phytochemical, ethnobotanical, biological, and pharmacological significance of the plant to provide directions for future research to find out therapeutically active lead compounds for developing new drugs against diseases of current interest including diabetes, inflammation, and cancer.

Copaifera of the Neotropics: A Review of the Phytochemistry and Pharmacology

The oleoresin of Copaifera trees has been widely used as a traditional medicine in Neotropical regions for thousands of years and remains a popular treatment for a variety of ailments. The copaiba resins are generally composed of a volatile oil made up largely of sesquiterpene hydrocarbons, such as β-caryophyllene, α-copaene, β-elemene, α-humulene, and germacrene D. In addition, the oleoresin is also made up of several biologically active diterpene acids, including copalic acid, kaurenoic acid, alepterolic acid, and polyalthic acid. This review presents a summary of the ecology and distribution of Copaifera species, the traditional uses, the biological activities, and the phytochemistry of copaiba oleoresins. In addition, several biomolecular targets relevant to the bioactivities have been implicated by molecular docking methods.

Synthesis, anticancer activity and mechanism of action of new thiazole derivatives

Thiazole derivatives are recognized to possess various biological activities as antiparasitic, antifungal, antimicrobial and antiproliferative. The present work reports the synthesis of 22 new substances belonging to two classes of compounds: thiosemicarbazones and thiazoles, with the purpose of developing new drugs that present high specificity for tumor cells and low toxicity to the organism. A cytotoxic screening was performed to evaluate the performance of the new derivatives in five tumor cell lines. Eight compounds were shown to be promising in at least three tumor cell lines. These compounds had their IC₅₀ determined within 72 h and the activity structure ratio was assessed. The effect of the best compounds on PBMC and hemolytic activity assay was then evaluated. The compound 1d was considered the most promising among the samples tested and its influence on cell cycle, DNA fragmentation and mitochondrial depolarization was evaluated.

The chemical composition and trypanocidal activity of volatile oils from Brazilian Caatinga plants

Essential/volatile oils (EOs) from plants used in the traditional medicine are known as a rich source of chemically diverse compounds with relevant biological activities. In this work we analysed the chemical composition and the in vitro effects of EOs from leaves of Eugenia brejoensis (EBEO), Hyptis pectinata (HPEO), Hypenia salzmannii (HSEO), Lippia macrophylla (LMEO) and seeds of Syagrus coronata (SCEO) on Trypanosoma cruzi, the etiological agent of Chagas disease. The EOs were extracted through hydrodistillation and its chemical composition analysed by GC/MS. The trypanocidal activity against epi- and trypomastigotes was evaluated by optical microscopy and the cytotoxicity to mammalian cells by MTT. The effects of EOs on parasite infection in macrophages were estimated by determining the survival index and the percentage of infection inhibition. The cytotoxicity against mammalian cells was compared to those of parasite by determining the Selectivity Index (SI). Overall, 114 compounds were identified: The main constituents of EOS were: δ-cadinene (15.88%), trans-caryophyllene (9.77%) e α-Muurolol (9.42%) for EBEO; trans-caryophyllene (15.24%), bicyclogermacrene (7.33%) e cis-calamenene (7.15%) for HFEO; trans-caryophyllene (30.91%), caryophyllene oxide (13.19%) and spathulenol (5.68%) for HPEO; Xanthoxylin (17.20%) trans-caryophyllene (14.34%) and methyl-eugenol (5.60%) for HSEO; Thymol (49.81%), carvacrol (31.6%) and σ-cimene (10.27%) for LMEO and octanoic acid (38.83%) dodecanoic acid (38.45%) and decanoic acid (20.51%) for SCEO. All the tested oils showed an inhibitory effect on the growth and survival of all forms of T. cruzi and moderate cytotoxicity towards the mammalian cells (100 < CC₅₀ < 500 μg/mL). The EO of E. brejoensis was the most effective against the parasite presenting higher Selectivity Index for trypo- (SI = 14.45) and amastigote forms (SI = 20.11). Except for SCEO, which was the most cytotoxic for both parasite and mammalian cells, all the oils demonstrated to be more selective for the parasite than the reference drug benznidazole. Taken together our results point the essential oils from Caatinga plants, especially Eugenia brejoensis, as promissory agents for the development of new drugs against Chagas disease.

Effect of diterpenoid kaurenoic acid on genotoxicity and cell cycle progression in gastric cancer cell lines

The goal of our study was to evaluate the effect of kaurenoic acid, obtained from copaiba oil resin, in gastric cancer (GC) and a normal mucosa of stomach (MNP01) cell lines. The compound was tested at concentrations of 2.5, 5, 10, 30 and 60μg/mL. Comet and micronucleus assays were used to access its potential genotoxicity in vitro. Moreover, we evaluated the effect of kaurenoic acid in cell cycle progression and in the transcription of genes involved in the control of the cell cycle: MYC, CCND1, BCL2, CASP3, ATM, CHK2 and TP53. Kaurenoic acid induced an increase on cell DNA damage or micronucleus frequencies on GC cell lines in a dose-dependent manner. The GC and MNP01 cell lines entering DNA synthesis and mitosis decreased significantly with kaurenoic acid treatment, and had an increased growth phase compared with non-treated cells. The treatment induced apoptosis (or necrosis) even at a concentration of 2.5μg/mL in relation to non-treated cells. GC cell lines presented reduced MYC, CCND1, BCL2 and CASP3 transcription while ATM, CHK2 and TP53 increased in transcription in relation to non-treated cells, especially at a concentration above 10μg/mL. The gene transcription in the MNP01 (non-treated non-cancer cell line) was designated as a calibrator for all the GC cell lines. In conclusion, our results showed that kaurenoic acid obtained from Copaifera induces DNA damage and increases the micronuclei frequency in a dose-dependent manner in GC cells, with a significant genotoxicity observed above the concentration of 5μg/mL. Moreover, this compound seems to be able to induce cell cycle arrest and apoptosis in GC cells.

Brazilian Amazon Traditional Medicine and the Treatment of Difficult to Heal Leishmaniasis Wounds with Copaifera

The present study describes the use of the traditional species Copaifera for treating wounds, such as ulcers scarring and antileishmanial wounds. It also relates phytochemical studies, evaluation of the leishmanicidal activity, and toxicity. The species of Copaifera with a higher incidence in the Amazon region are Copaifera officinalis, Copaifera reticulata, Copaifera multijuga Hayne. The copaiba oil is used in the Amazon's traditional medicine, especially as anti-inflammatory ingredient, in ulcers healing, and in scarring and for leishmaniasis. Chemical studies have shown that these oils contain diterpenes and sesquiterpenes. The copaiba oil and terpenes isolated have antiparasitic activity, more promising in the amastigote form of L. amazonensis. This activity is probably related to changes in the cell membrane and mitochondria. The oil showed low cytotoxicity and genotoxicity. Furthermore, it may interfere with immune response to infection and also has a healing effect. In summary, the copaiba oil is promising as leishmanicidal agent.

Chemical and biological studies of β-carotene after exposure to Cannabis sativa smoke

Considering the increase in consumption of Cannabis sativa and the use of the compound β-carotene (BC) as supplement, we investigated potential changes in the chemical and biological proprieties of BC after exposure to C. sativa smoke (CSS). Our results showed that the BC exposed to CSS underwent 98.8% degradation and suffered loss of its antiradical activity. The major degradation products identified were 3-hydroxy-2,4,4-trimethylpentyl)2-methylpropanoate and (2-ethyl-3-hydroxyhexyl)2-methylpropanoate compounds. These are found in higher levels in the exhalations of colorectal cancer patients and are similar to the toxic products associated with lipid peroxidation of polyunsaturated fatty acids. In toxicological assays using micro-crustacean Artemia salina the BC was non-toxic, while the BC degraded by CSS had a toxicity of LC₅₀ = 397.35 μg/mL. In Wistar rats, females treated with BC degraded by CSS (BCCSS) showed whitish liver spots, alterations in liver weight and in bilirubin and alkaline phosphatase levels, and decrease in the number of leukocytes associated with atypical lymphocytosis. In male rats, there was an increase in the number of leukocytes when compared to the control group. In the histopathological analysis, the cortical region of the kidneys showed the presence of discrete amorphous eosinophilic material (cylinders) in the lumen of the proximate and distal convoluted tubules. In general, the BC in contact with CSS undergoes chemical changes and exhibits toxicity to rats and Artemia salina.

Biological activities and cytotoxicity of diterpenes from Copaifera spp. Oleoresins

Copaifera spp. are Amazonian species widely studied and whose oleoresins are used by local people for various medicinal purposes. However, a detailed study of the activity of the main phytochemical components of these oleoresins remains to be done. Here, we studied the cytotoxicity and in vitro anti-inflammatory effects of six diterpene acids: copalic, 3-hydroxy-copalic, 3-acetoxy-copalic, hardwickiic, kolavic-15-metyl ester, and kaurenoic, isolated from the oleoresins of Copaifera spp. The diterpenes did not show cytotoxicity in normal cell lines, nor did they show significant changes in viability of tumoral line cells. The 3-hydroxy-copalic was able to inhibit the enzyme tyrosinase (64% ± 1.5%) at 250 µM. The kolavic-15-metyl ester at 200 µM showed high inhibitory effect on lipoxygenase (89.5% ± 1.2%). Among the diterpenes tested, only kaurenoic and copalic acids showed significant hemolytic activities with 61.7% and 38.4% at 100 µM, respectively. In addition, it was observed that only the copalic acid (98.5% ± 1.3%) and hardwickiic acid (92.7% ± 4.9%) at 100 mM inhibited nitric oxide production in macrophages activated by lipopolysaccharide. In this assay, the diterpenes did not inhibit tumor necrosis factor-α production. The acids inhibited the production of IL-6, 3-acetoxy-copalic (23.8% ± 8.2%), kaurenoic (11.2% ± 5.7%), kolavic-15-methyl ester (17.3% ± 4.2%), and copalic (4.2% ± 1.8%), respectively, at 25 µM. The kaurenoic, 3-acetoxy-copalic and copalic acids increased IL-10 production. This study may provide a basis for future studies on the therapeutic role of diterpenic acids in treating acute injuries such as inflammation or skin disorders.

A kinetic study of the main guaco metabolites using syrup formulation and the identification of an alternative route of coumarin metabolism in humans

For decades guaco species have been empirically used for the treatment of respiratory diseases. However, studies have shown that the toxic and therapeutic effects of the main guaco metabolites are dose-dependent, and none clinical study was done to evaluate the behavior of these substances in humans. In this work, a pilot study measuring the kinetic profile of the main guaco metabolites was performed leading to the knowledge of an alternative route of coumarin metabolism in humans. Initial screenings demonstrated that the administration of 60 mL of guaco syrup (single dose) did not provide sufficient levels of coumarin (COU), 7-hydroxycoumarin (7-HCOU), o-coumaric acid (OCA) and kaurenoic acid (KAU). The pharmacokinetic parameters were calculated by orally administering 60 mL of guaco syrup spiked with 1500 mg of COU. The kinetic study demonstrated that the plasmatic levels of 7-HCOU (considered the main metabolite of COU) were 10 times lower than the levels of COU, and the kinetic profile of 7-HCOU suggests sequential metabolism in the liver with low access of 7-HCOU to the systemic circulation. The study also demonstrated that OCA is one of the main bioavailable metabolites of COU. Therefore, the hydrolysis of the lactone ring forming a carboxylated compound is one of the possible routes of COU metabolism in humans. The half-lives of COU, 7-HCOU and OCA were approximately 4.0, 1.0 and 3.0 h, respectively and there was evidence that the recommended dosage of guaco syrup did not provide sufficient levels of COU, 7-HCOU or OCA to obtain a bronchodilation effect. Clinical studies are necessary to prove the efficacy and safety of products based on guaco.

Synthesis and biological evaluation of novel 6-hydroxy-benzo[d][1,3]oxathiol-2-one Schiff bases as potential anticancer agents

With the aim of discovering new anticancer agents, we have designed and synthesized novel 6-hydroxy-benzo[d][1,3]oxathiol-2-one Schiff bases. The synthesis started with the selective nitration at 5-position of 6-hydroxybenzo[d][1,3]oxathiol-2-one (1) leading to the nitro derivative 2. The nitro group of 2 was reduced to give the amino intermediate 3. Schiff bases 4a–r were obtained from coupling reactions between 3 and various benzaldehydes and heteroaromatic aldehydes. All the new compounds were fully identified and characterized by NMR (¹H and ¹³C) and specifically for 4q by X-ray crystallography. The in vitro cytotoxicity of the compounds was evaluated against cancer cell lines (ACP-03, SKMEL-19 and HCT-116) by using MTT assay. Schiff bases 4b and 4o exhibited promising cytotoxicity against ACP-03 and SKMEL-19, respectively, with IC₅₀ values lower than 5 μM. This class of compounds can be considered as a good starting point for the development of new lead molecules in the fight against cancer.

Promising medicinal plants for bioprospection in a Cerrado area of Chapada do Araripe, Northeastern Brazil

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional medical systems represent an important source of knowledge about the use of biodiversity. Ethnobotanical and ethnopharmacological studies can encourage bioprospecting in the pursuit and selection of promising medicinal plants. This study investigated the diversity of medicinal plants in a disjunct area of cerrado in Chapada do Araripe, Ceará, Brazil, and assessed the species of interest for bioprospecting.

MATERIALS AND METHODS

Structured and semi-structured interviews were conducted through free listing, and the informants were recruited using the "snowball" technique. The relative importance and informant consensus factor were analyzed for the selection of plant species with therapeutic potential.

RESULTS

A total of 68 species were recorded and cited for 91 therapeutic purposes. Of these, 10 species showed great versatility of use, including Copaifera langsdorffii Desf., Caryocar coriaceum Wittn., Himatanthus drasticus (Mart.) Plumel, Stryphnodendron rotundifolium Mart., and Dimorphandra garderiana Tull. The therapeutic citations were grouped into 16 categories of body systems, of which Injuries, Poisonings and Other Consequences of External Causes, and Neoplasias showed the highest agreement of use.

CONCLUSIONS

Regarding the diversity of the species, some including Tocoyena Formosa (Cham. & Schlecht.) Schum., Himatanthus drasticus, Caryocar coriaceum, Roupala montana Aubl. and Stryphnodendron rotundifolium showed both high relative importance and strong consensus among informants, and although many have already been investigated scientifically, others are almost unknown with respect to their medicinal properties and can be targets for bioprospecting.

Synthesis and anticancer activity of (E)-2-benzothiazole hydrazones

Benzothiazole hydrazones have been synthesized and evaluated for their in vitro antiproliferative activity against three human cancer cell lines: HL-60 (leukemia), MDAMB-435 (breast) and HCT-8 (colon). The good cytotoxicity for the three cancer cell lines and theoretical profile of compounds 3o and 3p pointed them as promising lead molecules for anticancer drug design.

The remarkable structural diversity achieved in ent-Kaurane Diterpenes by fungal biotransformations

The use of biotransformations in organic chemistry is widespread, with highlights of interesting applications in the functionalization of natural products containing unactivated carbons, like the kaurane diterpenes. A number of compounds with kaurane skeletons can be isolated in large amounts from several plant species and a myriad of biological activities has been related to these compounds. Studies on structure versus activity have showed that, in most cases, in kaurane diterpenes, activity increases with the increase of functionalization. Since naturally occurring kaurane diterpenes usually have limited functional groups to be used as targets for semi-synthetic modifications, production of more polar derivatives from kaurane diterpenes have been achieved mostly through the use of fungal biotransformations. In this review, selected examples the wonderful chemical diversity produced by fungi in kaurane diterpenes is presented. This diversity includes mainly hydroxylation of nearly all carbon atoms of the kaurane molecule, many of them carried out stereoselectively, as well as ring rearrangements, among other chemical modifications. Sources of starting materials, general biotransformation protocols employed, fungi with most consistent regioselectivity towards kaurane skeleton, as well as biological activities associated with starting materials and products are also described.

Mikania laevigata: chemical characterization and selective cytotoxic activity of extracts on tumor cell lines

Cancer is the second major cause of mortality worldwide, losing only to cardiovascular disease. Nowadays, around 50% of antineoplastic drugs were discovered and isolated by indications of plants in folk medicine. In Brazilian flora there are many species of plants which have great therapeutic importance, highlighting the Mikania laevigata (Asteraceae) that has been used for their valuable properties, especially in the respiratory tract. In the present study, the compounds of M. laevigata extracts were characterized by High Resolution Mass Spectrometry (HRMS) and Gas Chromatography with Mass analysis (GC/MS-EI). Therefore, the presence of some compounds with promising biological properties as antitumor activity was detected. Coumarin (1,2-benzopyrone) was previously reported as responsible for some biological activities of this plant species. Here, the extracts were evaluated by their cytotoxic activity against tumor (Hep-2, HeLa) and non tumor (MRC-5) cell lines, presenting significant inhibitory activity of cell growth in all extracts analyzed, chloroform, ethyl acetate, hexane, ethanol, which is related to its chemical composition. From the four different extracts here tested, two of them, hexane and ethanol, presented a clear selectivity against both tumor cells lines investigated. This can be explained by variances and increase of phenolic compounds in the ethanol fraction and an association of molecules with coumarin found in the hexane fraction.

Eugenia uniflora L. Essential Oil as a Potential Anti-Leishmania Agent: Effects on Leishmania amazonensis and Possible Mechanisms of Action

Eugenia uniflora L. is a member of the Myrtaceae family and is commonly known as Brazilian cherry tree. In this study, we evaluated the chemical composition of Eugenia uniflora L. essential oil (EuEO) by using gas chromatography-mass spectrometry (GC-MS) and assessed its anti-Leishmania activity. We also explored the potential mechanisms of action and cytotoxicity of EuEO. Thirty-two compounds were identified, which constituted 92.65% of the total oil composition. The most abundant components were sesquiterpenes (91.92%), with curzerene (47.3%), γ -elemene (14.25%), and trans- β -elemenone (10.4%) being the major constituents. The bioactivity shown by EuEO against promastigotes (IC50, 3.04  μ g·mL(-1)) and amastigotes (IC50, 1.92  μ g·mL(-1)) suggested significant anti-Leishmania activity. In the cytotoxicity determination, EuEO was 20 times more toxic to amastigotes than to macrophages. Hemolytic activity was 63.22% at the highest concentration tested (400  μ g·mL(-1)); however, there appeared to be no toxicity at 50  μ g·mL(-1). While the data show that EuEO activity is not mediated by nitric oxide production, they do suggest that macrophage activation may be involved in EuEO anti-Leishmania activity, as evidenced by increases in both the phagocytic capacity and the lysosomal activity. More studies are needed to determine in vivo activity as well as additional mechanisms of the anti-Leishmania activity.