FLASH radiotherapy for the treatment of symptomatic bone metastases in the thorax (FAST-02): protocol for a prospective study of a novel radiotherapy approach.

BACKGROUND: FLASH therapy is a treatment technique in which radiation is delivered at ultra-high dose rates (≥ 40 Gy/s). The first-in-human FAST-01 clinical trial demonstrated the clinical feasibility of proton FLASH in the treatment of extremity bone metastases. The objectives of this investigation are to assess the toxicities of treatment and pain relief in study participants with painful thoracic bone metastases treated with FLASH radiotherapy, as well as workflow metrics in a clinical setting. METHODS: This single-arm clinical trial is being conducted under an FDA investigational device exemption (IDE) approved for 10 patients with 1-3 painful bone metastases in the thorax, excluding bone metastases in the spine. Treatment will be 8 Gy in a single fraction administered at ≥ 40 Gy/s on a FLASH-enabled proton therapy system delivering a single transmission proton beam. Primary study endpoints are efficacy (pain relief) and safety. Patient questionnaires evaluating pain flare at the treatment site will be completed for 10 consecutive days post-RT. Pain response and adverse events (AEs) will be evaluated on the day of treatment and on day 7, day 15, months 1, 2, 3, 6, 9, and 12, and every 6 months thereafter. The outcomes for clinical workflow feasibility are the occurrence of any device issues as well as time on the treatment table. DISCUSSION: This prospective clinical trial will provide clinical data for evaluating the efficacy and safety of proton FLASH for palliation of bony metastases in the thorax. Positive findings will support the further exploration of FLASH radiation for other clinical indications including patient populations treated with curative intent. REGISTRATION: ClinicalTrials.gov NCT05524064.

Comparative assessment of radiation therapy-induced vasculitis using [18F]FDG-PET/CT in patients with non-small cell lung cancer treated with proton versus photon radiotherapy.

PURPOSE: To assess radiation therapy (RT)-induced vasculitis in patients with non-small cell lung cancer (NSCLC) by examining changes in the uptake of 18F-fluoro-D-deoxyglucose ([18F]FDG) by positron emission tomography/computed tomography (PET/CT) images of the ascending aorta (AA), descending aorta (DA), and aortic arch (AoA) before and after proton and photon RT. METHOD: Thirty-five consecutive locally advanced NSCLC patients were definitively treated with proton (n = 27) or photon (n = 8) RT and concurrent chemotherapy. The patients were prospectively enrolled to undergo [18F]FDG-PET/CT imaging before and 3 months after RT. An adaptive contrast-oriented thresholding algorithm was applied to generate mean standardized uptake values (SUVmean) for regions of interest (ROIs) 3 mm outside and 3 mm inside the outer perimeter of the AA, DA, and AoA. These ROIs were employed to exclusively select the aortic wall and remove the influence of blood pool activity. SUVmeans before and after RT were compared using two-tailed paired t-tests. RESULTS: RT treatments were associated with increased SUVmeans in the AA, DA, and AoA-1.9%, 0.3%, and 1.3% for proton and 15.8%, 9.5%, and 15.5% for photon, respectively. There was a statistically significant difference in the ∆SUVmean (post-RT SUVmean - pre-RT SUVmean) in patients treated with photon RT when compared to ∆SUVmean in patients treated with proton RT in the AA (p = 0.043) and AoA (p = 0.015). There was an average increase in SUVmean that was related to dose for photon patients (across structures), but that was not seen for proton patients, although the increase was not statistically significant. CONCLUSION: Our results suggest that patients treated with photon RT for NSCLC may exhibit significantly more RT-induced inflammation (measured as ∆SUVmean) in the AA and AoA when compared to patients who received proton RT. Knowledge gained from further analyses in larger cohorts could aid in treatment planning and help prevent the significant morbidity and mortality associated with RT-induced vascular complications. TRIAL REGISTRATION: NCT02135679.

Synthesis and antileukemic activity of an ursolic acid derivative: A potential co-drug in combination with imatinib.

Imatinib, a specific Bcr-Abl tyrosine kinase inhibitor, is the most commonly used drug in the treatment of chronic myeloid leukemia. However, optimal response is not achieved in up to 33% of patients. Therefore, development of novel therapeutic strategies for chronic myeloid leukemia is critical. Betulinic (1) and ursolic (2) acids are natural pentacyclic triterpenes that exhibit antileukemic activities. In this study, we evaluated the effects of pharmacomodulations at the C-3 position of the triterpene moiety of betulinic and ursolic acids on their activity against K562 leukemia cells. Six new derivatives (1a-2c) were synthesized and evaluated for pro-apoptotic and anti-proliferative effects in mammalian and leukemic cells. 2c derivative containing an amine group at the C-3 position of ursolic acid was the most active against leukemia cells with an IC50 value of 5.2 µM after 48 h of treatment. 2c did not exhibit cytotoxic effects against VERO and HepG2 cells and human lymphocytes, showing a good selectivity index for cancer over normal cells. Induced cell death by apoptosis via caspases 3 and 8, and also caused cell cycle arrest as evidenced by accumulation of cells in the G1 phase and decreased cell population in the G2 phase. Furthermore, co-treatment of 2c with imatinib, the chemotherapy drug most commonly used to treat leukemia, resulted in a synergistic effect. Our findings provide a strong rationale for further investigation of combination therapy using the 2c derivative and imatinib in pre-clinical studies.

CT for detection of malignant posterior intercostal lymph nodes in patients undergoing pre-operative staging for malignant pleural mesothelioma.

INTRODUCTION: Recent evidence suggests that patients with malignant pleural mesothelioma (MPM) undergoing extended pleurectomy/decortication (eP/D) with metastasis to the posterior intercostal lymph nodes (PILN) have a worse prognosis. In this study, we determine if MPM PILN metastasis can be reliably detected on computed tomography (CT). MATERIALS AND METHODS: Preoperative staging CT exams were reviewed for the presence of PILN in MPM patients undergoing eP/D between 2007-2013 with surgical sampling of their PILN. CT images were reviewed by two thoracic radiologists blinded to clinical records, including operative pathology reports. The number and short axis size of PILN were recorded and correlated with surgical pathology. Statistical analysis examined the value of preoperative CT to detect metastatic PILN. RESULTS: Of 36 patients that underwent eP/D with PILN sampling had preoperative CT images for review. At surgery, 22 of these patients had metastatic PILN and 14 had benign PILN. The positive and negative predictive values for one or more nodes seen on preoperative CT were 60 % and 38 % respectively. The number of PILN on preoperative CT did not predict metastasis (p = 0.40) with an average of 2 PILN seen, regardless of PILN pathology. The average nodal short axis size was 4.6 mm and 4.8 mm for benign and malignant PILN, respectively, and PILN short axis size did not predict metastasis (p = 0.39). There was little inter-observer variability between the size and number of nodes detected by each radiologist. CONCLUSIONS: CT does not reliably identify metastatic PILN on preoperative CT for patients with MPM undergoing extended pleurectomy/decortication.

Safety of thoracic radiotherapy in patients with prior immune-related adverse events from immune checkpoint inhibitors.

BACKGROUND: Immune checkpoint inhibitors (ICIs) and thoracic radiotherapy are increasingly used to treat advanced cancers. Despite data indicating exaggerated radiation toxicities in patients with autoimmune disease, the safety of thoracic radiotherapy in patients with prior ICI-associated immune-related adverse events (irAEs) is undefined. PATIENTS AND METHODS: Patients treated from 2014 to 2020 with ICIs were queried for receipt of corticosteroids and radiotherapy. Patients who received thoracic radiation after symptomatic irAEs were assessed for ≥grade 2 radiation pneumonitis (RP). Characteristics predictive of RP were assessed using logistic regression and response relationships were modeled. RESULTS: Among 496 assessed patients, 41 with irAE history subsequently treated with thoracic radiotherapy were analyzed. Most irAEs were grade 2 (n = 21) and 3 (n = 19). Median time from irAE onset to radiotherapy was 8.1 months. Most patients received stereotactic body radiation therapy (n = 20) or hypofractionated radiotherapy (n = 18). In total, 25 patients (61%) developed ≥grade 2 RP at a median of 4 months from radiotherapy and 11 months from onset of irAEs. Three months from RP onset, 16 of 24 (67%) assessable patients had persistent symptoms. Among patients with prior ICI pneumonitis (n = 6), five patients (83%) developed ≥grade 2 RP (grade 2, n = 3; grade ≥3, n = 2). The mean lung radiation dose (MLD) predicted for RP (odds ratio: 1.60, P = 0.00002). The relationship between MLD and RP was strong (area under the receiver-operating characteristic curve: 0.85) and showed an exaggerated dose-response. Among patients with an MLD >5 Gy (n = 26), 21 patients (81%) developed ≥grade 2 RP. CONCLUSION: This is the first study assessing the toxicity of radiotherapy among patients with prior irAEs from ICIs. Patients with prior irAEs were found to be at very high risk for clinically significant and persistent RP from thoracic radiotherapy. Careful consideration should be given to the possibility of an increased risk of RP, and close monitoring is recommended in these patients.

Betulinic Acid and Brosimine B Hybrid Derivatives as Potential Agents against Female Cancers.

BACKGROUND: Cancer is a multifactorial disease, representing one of the leading causes of death worldwide. On a global estimate, breast cancer is the most frequently occurring cancer in women and cervical cancer, the fourth most common. Both types of cancer remain the major cause of cancer-related mortality in developing countries. A strategy for rational drug design is hybridization, which aims to bring together in one molecule, two or more pharmacophores in order to reach several biological targets. OBJECTIVE: The objective of this work was to develop new hybrids based on natural pharmacophores: Betulinic acid (1) and brosimine b (2), active in female cancer cell lines. METHODS: The coupling reactions were carried out by Steglich esterification. Different compounds were designed for the complete and simplified structural hybridization of molecules. The anticancer activities of the compounds were evaluated in human cervical adenocarcinoma (HeLa), human cervical metastatic epidermoid carcinoma (ME-180), and human breast adenocarcinoma (MCF-7) cell lines. RESULTS: Hybrid 3 presented higher potency (IC50 = 9.2 ± 0.5µM) and SI (43.5) selectively in MCF-7 cells (in relation to Vero cells) with its cytotoxic effect occurring via apoptosis. In addition, compound 6 showed activity in MCF-7 and HeLa cells with intermediate potency, but with high efficacy, acting via apoptosis as well. CONCLUSION: In this context, we showed that the combination of two complex structures generated the development of hybrids with differing inhibitory profiles and apoptotic modes of action, thus representing potential alternatives in female cancer treatment.

A Highly Active Triterpene Derivative Capable |of Biofilm Damage to Control Cryptococcus spp.

Cryptococcus neoformans is an encapsulated yeast responsible for more than 180,000 deaths per year. The standard therapeutic approach against cryptococcosis is a combination of amphotericin B with flucytosine. In countries where cryptococcosis is most prevalent, 5-fluorocytosine is rarely available, and amphotericin B requires intravenous administration. C. neoformans biofilm formation is related to increased drug resistance, which is an important outcome for hospitalized patients. Here, we describe new molecules with anti-cryptococcal activity. A collection of 66 semisynthetic derivatives of ursolic acid and betulinic acid was tested against mature biofilms of C. neoformans at 25 µM. Out of these, eight derivatives including terpenes, benzazoles, flavonoids, and quinolines were able to cause damage and eradicate mature biofilms. Four terpene compounds demonstrated significative growth inhibition of C. neoformans. Our study identified a pentacyclic triterpenoid derived from betulinic acid (LAFIS13) as a potential drug for anti-cryptococcal treatment. This compound appears to be highly active with low toxicity at minimal inhibitory concentration and capable of biofilm eradication.

SERCA plays a crucial role in the toxicity of a betulinic acid derivative with potential antimalarial activity.

Malaria is one of the most significant infectious diseases that affect poor populations in tropical areas throughout the world. Plants have been shown to be a good source for the development of new antimalarial chemotherapeutic agents, as shown for the discovery of quinine and artemisinin derivatives. Our research group has been working with semisynthetic triterpene derivatives that show potential antimalarial activity toward different strains of Plasmodium falciparum by specifically modulating calcium pathways in the parasite. Promising results were obtained for nanomolar concentrations of the semisynthetic betulinic acid derivative LAFIS13 against the P. falciparum 3D7 strain in vitro, with a selectivity index of 18 compared to a mammalian cell line. Continuing these studies, we present here in vitro and in vivo toxicological evaluations of this compound, followed by docking studies with PfATP6, a sarco/endoplasmic reticulum Ca+2-ATPase (SERCA) protein. LAFIS13 showed an LD50 between 300 and 50 mg/kg, and the acute administration of 50 mg/kg (i.p.) had no negative effects on hematological, biochemical and histopathological parameters. Based on the results of the in vitro assays, LAFIS13 not exerted significant effects on coagulation parameters of human peripheral blood, but a hemolytic activity was verified at higher concentrations. According to the molecular docking study, the PfATP6 protein may be a target for LAFIS13, which corroborates its previously reported modulatory effects on calcium homeostasis in the parasite. Notably, LAFIS13 showed a higher selectivity for the mammalian SERCA protein than for PfATP6, thus impairing the selectivity between parasite and host. In summary, the direct interaction with calcium pumps and the hemolytic potential of the compound proved to be plausible mechanism of LAFIS13 toxicity.

Predicted Rate of Secondary Malignancies Following Adjuvant Proton Versus Photon Radiation Therapy for Thymoma.

PURPOSE: Thymic malignancies are the most common tumors of the anterior mediastinum. The benefit of adjuvant radiation therapy for stage II disease remains controversial, and patients treated with adjuvant radiation therapy are at risk of late complications, including radiation-induced secondary malignant neoplasms (SMNs), that may reduce the overall benefit of treatment. We assess the risk of predicted SMNs following adjuvant proton radiation therapy compared with photon radiation therapy after resection of stage II thymic malignancies to determine whether proton therapy improves the risk-benefit ratio. METHODS AND MATERIALS: Ten consecutive patients treated with double-scattered proton beam radiation therapy (DS-PBT) were prospectively enrolled in an institutional review board-approved proton registry study. All patients were treated with DS-PBT. Intensity modulated radiation therapy (IMRT) plans for comparison were generated. SMN risk was calculated based on organ equivalent dose. RESULTS: Patients had a median age of 65 years (range, 25-77 years), and 60% were men. All patients had stage II disease, and many had close or positive margins (60%). The median dose was 50.4 Gy (range, 50.4-54.0 Gy) in 1.8-Gy relative biological effectiveness daily fractions. No differences in target coverage were seen with DS-PBT compared with IMRT plans. Significant reductions were seen in mean and volumetric lung, heart, and esophageal doses with DS-PBT compared with IMRT plans (all P≤.01). Significant reductions in SMNs in the lung, breast, esophagus, skin, and stomach were seen with DS-PBT compared with IMRT. For patients with thymoma diagnosed at the median national age, 5 excess secondary malignancies per 100 patients would be avoided by treating them with protons instead of photons. CONCLUSIONS: Treatment with proton therapy can achieve comparable target coverage but significantly reduced doses to critical normal structures, which can lead to fewer predicted SMNs compared with IMRT. By decreasing expected late complications, proton therapy may improve the therapeutic ratio of adjuvant radiation therapy for patients with stage II thymic malignancies.

Design, Synthesis and Biological Evaluation of Betulinic Acid Derivatives as New Antitumor Agents for Leukemia.

BACKGROUND: Chronic myeloid leukemia (CML) is currently treated with imatinib, a Bcr-Abl inhibitor. However, resistance to this drug usually develops over time. Triptolide, a diterpenoid triepoxide, has been shown active against CML cells resistant to imatinib, acting mainly on the level of Bcr-Abl transcription inhibition. OBJECTIVE: Here, we used the triterpene betulinic acid, a known proteasome inhibitor with potential antileukemic activity, as a scaffold for the generation of analogues with predicted triptolide biological activity. METHOD: Betulinic acid derivatives were designed based on the structure-activity relationship of triptolide and evaluated for their cytotoxic effects in CML cells, lymphocytes and human keratinocytes (HaCaT), as well as against the proteasome complex. The main modification performed on betulinic acid was fluorination at C-28 and epoxidation, both of which are responsible for enhancing activity of triptolide. A total of 10 compounds were obtained: 6 previously described and 4 novel compounds. The cytotoxic activity over a CML cell line (K562) was assessed using flow cytometry and compared to lymphocytes and HaCaT. RESULT: The results show that betulinic acid was the most cytotoxic compound against CML cells, showing a good selectivity index for cancer over normal cells. The most important trend for the activity in betulinic acid derivatives is the presence of a free hydroxyl group at C-3 and a carboxyl group at C-28. Results also indicated that the epoxide is important for enhancing the activity, while modification at C-28 worsens the activity. CONCLUSION: Proteasome inhibition assays suggest that proteasome is the main target for betulinic acid and its derivatives.

Quercetin derivative induces cell death in glioma cells by modulating NF-κB nuclear translocation and caspase-3 activation.

Treated glioblastoma multiforme (GBM) patients only survive 6 to 14months after diagnosis; therefore, the development of novel therapeutic strategies to treat gliomas remains critically necessary. Considering that phenolic compounds, like quercetin, have the potential to be used in the chemotreatment of gliomas and that some flavonoids exhibit the ability to cross the BBB, in the present study, we investigated the antitumor effect of flavonoids (including chalcones, flavones, flavanones and flavonols). Initially their activities were tested in C6 glioma cells screened using the MTT method, resulting in the selection of chalcone 2 whose feasibility was confirmed by a Trypan Blue exclusion assay in the low µM range on C6 glioma cells. Cell cycle and apoptotic death analyses on C6 glioma cells were also performed, and chalcone 2 increased the apoptosis of the cells but did not alter the cell cycle progression. In addition, treatments with these two compounds were not cytotoxic to hippocampal organotypic cultures, a model of healthy neural cells. Furthermore, the results indicated that 2 induced apoptosis by inhibition of NF-κB and activation of active caspase-3 in glioma cells, suggesting that it is a potential prototype to develop new treatments for GBM in the future.

Synthesis and biological evaluation of hydrazone derivatives as antifungal agents.

Emerging yeasts are among the most prevalent causes of systemic infections with high mortality rates and there is an urgent need to develop specific, effective and non-toxic antifungal agents to respond to this issue. In this study 35 aldehydes, hydrazones and hydrazines were obtained and their antifungal activity was evaluated against Candida species (C. parapsilosis, C. tropicalis, C. krusei, C. albicans, C. glabrata and C. lusitaneae) and Trichosporon asahii, in an in vitro screening. The minimum inhibitory concentrations (MICs) of the active compounds in the screening was determined against 10 clinical isolates of C. parapsilosis and 10 of T. asahii. The compounds 4-pyridin-2-ylbenzaldehyde] (13a) and tert-butyl-(2Z)-2-(3,4,5-trihydroxybenzylidine)hydrazine carboxylate (7b) showed the most promising MIC values in the range of 16-32 µg/mL and 8-16 µg/mL, respectively. The compounds' action on the stability of the cell membrane and cell wall was evaluated, which suggested the action of the compounds on the fungal cell membrane. Cell viability of leukocytes and an alkaline comet assay were performed to evaluate the cytotoxicity. Compound 13a was not cytotoxic at the active concentrations. These results support the discovery of promising candidates for the development of new antifungal agents.

Investigation of antimalarial activity, cytotoxicity and action mechanism of piperazine derivatives of betulinic acid.

OBJECTIVES: To semisynthesise piperazine derivatives of betulinic acid to evaluate antimalarial activity, cytotoxicity and action mechanism. METHODS: The new derivatives were evaluated against the CQ-sensitive Plasmodium falciparum 3D7 strain by flow cytometry (FC) using YOYO-1 as stain. Cytotoxicity of 4a and 4b was performed with HEK293T cells for 24 and 48 h by MTT assay. The capability of compound 4a to modulate Ca(2+) in the trophozoite stage was investigated. The trophozoites were stained with Fluo4-AM and analysed by spectrofluorimetry. Effect on mitochondrial membrane potential (ΔΨm) was tested for 4a by FC with DiOC6 (3) as stain. For ß-haematin assay, 4a was incubated for 24 h with reagents such as haemin, and the fluorescence was measured by FlexStation at an absorbance of 405 nm. RESULTS: Antimalarial activity of 4a and 4b was IC50 = 1 and 4 µm, respectively. Compound 4a displayed cytotoxicity with IC50 = 69 and 29 µm for 24 and 48 h, respectively, and 4b was not cytotoxic at the tested concentrations. Addition of 4a leads to an increase in cytosolic Ca(2+) . We have measured ΔΨm after treating parasites with the compound. Data on Figure 4a show that mitochondria were not affected. The action mechanism for 4a, inhibition of ß-haematin formation (17%), was lower than CQ treatment (83%; IC50 = 3 mm). CONCLUSION: Compound 4a showed excellent antimalarial activity, and its action mechanism is involved in Ca(2+) pathway(s).

Synthesis of isosteric triterpenoid derivatives and antifungal activity.

Dermatomycoses are among the most widespread and common superficial and cutaneous fungal infections in humans. There is an urgent need to develop efficient and non-toxic antimycotic agents with a specific spectrum of activity. Triterpenes have been demonstrated to exhibit a wide range of biological activities, including antifungal activities. In this study, through hemisynthesis, we aimed to obtain triterpene-isosteric molecules from betulinic and ursolic acids to improve the antifungal activity and spectrum of action of these compounds. Six compounds were resynthesized and tested against eleven mucocutaneous and cutaneous mycotic agents. The results of the susceptibility assays were expressed as the minimal inhibitory concentration (MIC). The MIC values of the piperazinyl derivatives of ursolic and betulinic acids that were active against pathogenic yeasts were in the range of 16-32 µg/mL and 4-16 µg/mL, respectively, whereas fungicidal effects were observed at concentrations ranging from 16 to 128 µg/mL and 8 to 128 µg/mL, respectively. The piperazinyl derivative of betulinic acid exhibited an antifungal profile similar to that of terbinafine and was the most effective derivative against dermatophytes. This strategy led to a promising candidate for the development of a new antifungal agent.

The inhibitory effects of phenolic and terpenoid compounds from Baccharis trimera in Siha cells: differences in their activity and mechanism of action.

Baccharis trimera is used in folk medicine as a tea for digestive and liver diseases. It possesses anti-inflammatory and antioxidant properties that are related to the presence of phenolic compounds. The aim of this work was to investigate the anti-proliferative properties of phenolic (PHE) and terpenoid (SAP) compounds from B. trimera on human cervical cancer. The treatment of SiHa cells with PHE for 24 h suppressed colony formation in a dose-dependent manner, inhibited proliferation and inhibited cell motility. Although SAP inhibited the proliferation of SiHa cells in a dose-dependent manner, it increased colony formation and did not inhibit cell motility. PHE and SAP also promoted a significant increase in lactate dehydrogenase levels in the culture medium in a dose-dependent manner, indicating a loss of cell membrane integrity. Moreover, PHE promoted necrotic cell death, whereas SAP induced apoptosis. These compounds are new anticancer prototypes due their significant anticancer activity demonstrated herein.

Improving the thrombin inhibitory activity of glycyrrhizin, a triterpenic saponin, through a molecular simplification of the carbohydrate moiety.

Glycyrrhizin, a saponin, and its aglycone glycyrrhetinic acid are natural products found in the Liquorice (Glycyrrhiza glabra L.) root extract. This saponin is known for its in vitro and in vivo thrombin inhibitory activity. The design and synthesis of five glycyrrhizin derivatives were carried out to improve the natural product activity. Compound 3b, a phthalic ester derivative of glycyrrhizin, presented a more pronounced thrombin inhibition (IC50  = 114.4 ± 1.3 µm) than the saponin (IC50  = 235.7 ± 1.4 µm). Molecular docking simulations performed to investigate the molecular interaction between compound 3b and the enzyme indicate that this product is, as previously determined for glycyrrhizin, an allosteric thrombin inhibitor.

Two series of new semisynthetic triterpene derivatives: differences in anti-malarial activity, cytotoxicity and mechanism of action.

BACKGROUND: The discovery and development of anti-malarial compounds of plant origin and semisynthetic derivatives thereof, such as quinine (QN) and chloroquine (CQ), has highlighted the importance of these compounds in the treatment of malaria. Ursolic acid analogues bearing an acetyl group at C-3 have demonstrated significant anti-malarial activity. With this in mind, two new series of betulinic acid (BA) and ursolic acid (UA) derivatives with ester groups at C-3 were synthesized in an attempt to improve anti-malarial activity, reduce cytotoxicity, and search for new targets. In vitro activity against CQ-sensitive Plasmodium falciparum 3D7 and an evaluation of cytotoxicity in a mammalian cell line (HEK293T) are reported. Furthermore, two possible mechanisms of action of anti-malarial compounds have been evaluated: effects on mitochondrial membrane potential (ΔΨm) and inhibition of ß-haematin formation. RESULTS: Among the 18 derivatives synthesized, those having shorter side chains were most effective against CQ-sensitive P. falciparum 3D7, and were non-cytotoxic. These derivatives were three to five times more active than BA and UA. A DiOC(6)(3) ΔΨm assay showed that mitochondria are not involved in their mechanism of action. Inhibition of ß-haematin formation by the active derivatives was weaker than with CQ. Compounds of the BA series were generally more active against P. falciparum 3D7 than those of the UA series. CONCLUSIONS: Three new anti-malarial prototypes were obtained from natural sources through an easy and relatively inexpensive synthesis. They represent an alternative for new lead compounds for anti-malarial chemotherapy.

Synthesis and antiplasmodial activity of betulinic acid and ursolic acid analogues.

More than 40% of the World population is at risk of contracting malaria, which affects primarily poor populations in tropical and subtropical areas. Antimalarial pharmacotherapy has utilised plant-derived products such as quinine and artemisinin as well as their derivatives. However, worldwide use of these antimalarials has caused the spread of resistant parasites, resulting in increased malaria morbidity and mortality. Considering that the literature has demonstrated the antimalarial potential of triterpenes, specially betulinic acid (1) and ursolic acid (2), this study investigated the antimalarial activity against P. falciparum chloroquine-sensitive 3D7 strain of some new derivatives of 1 and 2 with modifications at C-3 and C-28. The antiplasmodial study employed flow cytometry and spectrofluorimetric analyses using YOYO-1, dihydroethidium and Fluo4/AM for staining. Among the six analogues obtained, compounds 1c and 2c showed excellent activity (IC50 = 220 and 175 nM, respectively) while 1a and b demonstrated good activity (IC50 = 4 and 5 µM, respectively). After cytotoxicity evaluation against HEK293T cells, 1a was not toxic, while 1c and 2c showed IC50 of 4 µM and a selectivity index (SI) value of 18 and 23, respectively. Moreover, compound 2c, which presents the best antiplasmodial activity, is involved in the calcium-regulated pathway(s).

Phenolic enriched extract of Baccharis trimera presents anti-inflammatory and antioxidant activities.

Baccharis trimera is a plant popularly used as a tea and to treat gastrointestinal diseases and inflammatory processes as well. The total phenolic content was determined and the antioxidant and anti-inflammatory activities of six extracts (dichloromethane, ethyl acetate, butanol, aqueous, saponin and phenolic) from B. trimera were evaluated. Using carrageenan-induced pleurisy as a model of acute inflammation, the phenolic extract at 15 mg/kg decreased significantly the analyzed parameters when compared to the carrageenan group ( p < 0.05), thus showing potential anti-inflammatory activity. The total phenolic content and antioxidant activity were evaluated by the Folin-Ciocalteau and DPPH methods, respectively. Phenolic and ethyl acetate extracts presented higher antioxidant activity ( p < 0.05) than ascorbic acid. The phenolic extract also showed the highest antioxidant potential in relation to the other extracts, thus suggesting that the antioxidant and anti-inflammatory activities were due to the presence of phenolic compounds.