Search Results (32)

Background/Objectives: Seasonal waves of respiratory viruses—including SARS-CoV-2, influenza A virus (IAV), and respiratory syncytial virus (RSV)—continue to pose a global health burden and highlight the need for antiviral agents that are effective, safe, broadly active, affordable, and widely accessible. Current interventions are limited by the need for their early administration, the risk of resistance, their costs, and the restricted availability in large parts of the world. For certain natural products, such as European black elderberry (Sambucus nigra L.) fruit extract (ElderCraft^®; EC) and the seaweed-derived sulfated polymer iota-carrageenan (IC), antiviral activities against respiratory viruses, particularly IAV and SARS-CoV-2, have previously been shown. Here, we assessed the antiviral activity of IC and an anthocyanin-standardized EC extract against SARS-CoV-2, IAV, and RSV, either as monotherapy or in multiple-dose combinations. Methods: MDCKII cells were infected with IAV_PR8, human Calu-3 lung epithelial cells with the SARS-CoV-2 Omicron variant, and HEp-2 cells with RSV (A2 strain). Inhibitors were administered either by pre-incubation of cell-free virions prior to infection or, in separate time-of-addition experiments, during or post-infection. Viral replication was quantified by qRT-PCR or intracellular immunostaining. Cytotoxicity was evaluated using a neutral red uptake assay. Results: Most intriguingly, both EC and IC are able to neutralize virions derived from SARS-CoV-2, IAV, or RSV extracellularly in a dose-dependent manner. Notably, EC and IC alone exhibited strong anti-RSV activity, which was not reported previously. Most importantly, combined treatment with IC and EC caused a pronounced synergistic antiviral effect against the tested viruses, as confirmed by the Bliss independence model, without any detectable impact on cell viability. Finally, solutions prepared from matrix-standardized mono- or combi-lozenges, containing IC and/or EC in high or low doses, reproduced the antiviral and synergistic combination effects observed with the pure compounds. Conclusions: In summary, these findings support further development of EC and IC as a topically accessible, virion-neutralizing combination (e.g., lozenges) to provide additional protection against major respiratory viruses and potentially strengthen pandemic preparedness. Full article

Background: Overcoming therapeutic resistance and tumor microenvironment-mediated survival remains a major challenge in ovarian cancer treatment. This study investigated the individual and combined antitumor effects of etoposide and curcumin in human ovarian cancer models, with emphasis on synergistic interactions, apoptosis induction, tumor microenvironment modulation, and oxidative stress-associated mechanisms. We hypothesized that the combination of etoposide and curcumin exerts enhanced antitumor activity through an integrated mechanism involving DNA damage-associated apoptotic signaling, tumor microenvironment modulation, and ROS-associated cellular stress, rather than through a single dominant pathway. Methods: Cell viability was assessed using the MTT assay, and drug–drug interactions were quantitatively evaluated using the Chou–Talalay and Bliss independence models. Apoptosis was analyzed by Annexin V/propidium iodide flow cytometry, caspase-8/9 activity assays, and cell cycle analysis. Transcriptional regulation of apoptosis- and microenvironment-related genes was examined by quantitative real-time PCR. Inflammatory and angiogenic cytokines were measured by ELISA. Therapeutic efficacy was further validated in three-dimensional (3D) tumor spheroid models using morphological assessment and adenosine triphosphate (ATP)-based viability assays. The contribution of reactive oxygen species (ROS) was evaluated using antioxidant pretreatment. Results: The etoposide–curcumin combination demonstrated significantly enhanced antiproliferative and pro-apoptotic effects compared with either agent alone, with consistent synergism observed across quantitative interaction models. Combination treatment increased apoptotic cell death, activated both intrinsic and extrinsic apoptotic pathways, and induced G2/M cell cycle arrest. In parallel, inflammatory and angiogenic signaling was markedly suppressed at both transcriptional and protein levels. These effects were preserved and amplified in 3D tumor spheroid models, where combination therapy induced pronounced spheroid shrinkage and reduced viability. Antioxidant pretreatment partially attenuated ROS generation and cytotoxicity, indicating that oxidative stress contributes to, but does not fully account for, the observed antitumor effects. Conclusions: The combination of etoposide and curcumin exerts synergistic and multi-layered antitumor effects in ovarian cancer models by integrating apoptosis induction, tumor microenvironment modulation, and ROS-associated mechanisms. These findings support further preclinical evaluation of this combination as a rational therapeutic strategy for ovarian cancer. Full article

Environmental pollutants are persistent chemicals that pose substantial risks to human health, contributing to global mortality and economic burden. In real-world situations, exposure rarely occurs to single compounds; instead, people are chronically exposed to complex mixtures at low concentrations. However, most regulatory frameworks still rely on single-substance risk assessments, potentially underestimating the hazards associated with combined exposures. This study investigated the cytotoxic interactions of binary mixtures of five environmentally relevant pollutants: bisphenol A (BPA), bisphenol A diglycidyl ether (BADGE), dibutyl phthalate (DBP), di(2-ethylhexyl) phthalate (DEHP), and perfluorooctanoic acid (PFOA), using the human lymphoblast cell line NALM-6. Cells were exposed for 72 h to each compound individually and to all possible binary combinations, reflecting concentrations reported in human plasma or serum. Cell viability was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and interactions were analyzed using the Bliss model of independence and two-way analysis of variance (ANOVA). Intracellular reactive oxygen species were measured using the 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) probe to explore the involvement of oxidative stress. Synergistic interactions were observed under specific conditions, although not all statistically identified interactions corresponded to biologically significant effects. The BPA-DBP combination produced the highest cytotoxicity when both pollutants were present at 100 nM (31%), consistent with a strong synergistic effect. A similar pattern was observed for BADGE-BPA. ROS production was partially associated with cytotoxicity in these selected mixtures. Overall, these findings highlight the importance of distinguishing statistical synergy from toxicological relevance. Full article

Colorectal cancer (CRC) remains a leading cause of cancer-related mortality, with resistance to 5-fluorouracil (5-FU) representing a major therapeutic challenge. Thymoquinone (TQ), a bioactive constituent of Nigella sativa, exhibits anticancer activity; however, the mechanisms underlying TQ-induced cell death appear to be highly context dependent. This study aimed to characterize cell line-specific death pathways triggered by TQ in colorectal cancer models with distinct molecular backgrounds and differential responsiveness to 5-FU. Human CRC cell lines RKO (5-FU-sensitive) and SW1116 (poorly responsive), along with normal colon epithelial cells (CCD-841CoN), were treated with TQ, 5-FU, or their combination for 24 h. Cell viability, DNA fragmentation, caspase-3/7, -8, and -9 activity, cell death phenotypes, and expression of apoptosis- and necroptosis-related genes were evaluated using MTT assays, ELISA, luminescent assays, flow cytometry, and RT-qPCR. TQ significantly reduced viability in both CRC cell lines while exerting minimal cytotoxicity toward normal cells. In RKO cells, characterized by microsatellite instability (MSI), TQ induced DNA fragmentation, caspase activation, and transcriptional upregulation of pro-apoptotic genes, consistent with apoptosis-associated signaling. In contrast, SW1116 cells, which exhibit chromosomal instability (CIN) and reduced responsiveness to 5-FU, displayed decreased viability accompanied by suppressed caspase activity and predominant features of caspase-independent necrotic cell death. This differential response may be attributed to the CIN phenotype, which has been associated with impaired apoptotic signaling and enhanced tolerance to cytotoxic stress. Combined TQ and 5-FU treatment did not produce synergistic cytotoxicity, as confirmed by Bliss independence analysis, but revealed distinct, cell line-dependent death programs. These findings demonstrate that TQ modulates cell death execution in a molecular context-dependent manner rather than enhancing 5-FU efficacy through pharmacological synergy. Full article

Tempol, a synthetic nitroxide, exhibits dual antioxidant and pro-oxidant activity, requiring millimolar concentrations to induce oxidative stress, which limits its therapeutic use. Glutathione Peroxidase 4 (GPX4) is a critical lipid peroxidase that prevents ferroptosis, and its inhibition has emerged as a strategy to sensitize cancer cells to oxidative stress. To enhance Tempol’s efficacy, we investigated its interaction with ML210, a GPX4 inhibitor, in human colon (HT29) and gastric (CRL-1739) cancer cell lines. We quantified cell viability, oxidative stress markers (H₂O₂, Total Oxidant Status (TOS), and Total Antioxidant Status (TAS)) and endoplasmic reticulum (ER) stress proteins (ATF6, GRP78, and IRE1α) in in vitro assays. Synergy was assessed using Bliss independence analysis. The combination of Tempol (2 mM) and ML210 (0.05 μM) markedly reduced viability in both cell lines. Bliss analysis revealed slight/moderate synergy for cytotoxicity (Δ = +0.15 in HT29; Δ = +0.26 in CRL-1739) and strong synergy for H₂O₂ accumulation (Δ = +1.92–2.23 across replicates). In contrast, TOS showed moderate-to-strong antagonism across both cell lines, and TAS demonstrated slight synergistic or antagonistic effects. ER stress markers exhibited marker and cell line specific synergy: ATF6 showed strong synergy, IRE1α slight synergy in both lines, and GRP78 activation was highly variable, showing strong synergy in CRL-1739 cells but moderate antagonism in HT29 cells. These findings indicate that the cooperative action of Tempol and ML210 is ROS-pool–specific and pathway-selective in the ER. These findings demonstrate that ML210 potentiates Tempol’s pro-oxidant pressure by targeting GPX4, selectively amplifying H₂O₂ accumulation and ER stress engagement without collapsing global redox balance. This study provides mechanistic rationale for redox–proteostasis co-targeting in gastric and colon cancers and establishes a foundation for in vivo validation. Full article

In many practical scientific studies, two-way analysis of variance (ANOVA) and linear response surface methods are used for determining whether two or more similar compounds (substances, agents, or drugs) interact synergistically, antagonistically or independently. These models are often found lacking both in the means to assess interaction and with sufficient power. Using ten judiciously chosen illustrations (spanning fields as diverse as aquatic and environmental toxicology, botany, entomology, oncology, pharmacology, and virology), this paper introduces, explores, quantifies, illustrates, interprets, and extends several cutting-edge nonlinear assessment models and methods for measuring and describing interaction. Developed and used here are the Finney and Separate Ray models and extensions, a new cut line approach useful for so-called web designs, and extensions to more than two substances. As noted in the provided examples, the Finney model and extensions have the advantage of characterizing nonlinear interaction in a single measure, whereas the Separate Ray model extension is required when nonlinear interaction requires more than a single parameter for interaction assessment. The interaction results of the ten illustrations—of which antagonism is observed in four examples, synergy in five examples, and mixed results in one example—are summarized below. A discussion is also provided of efficient experimental design strategies as an aid to the practitioner and their future scientific studies. Full article

Background/Objectives: The persistent threat of emerging respiratory RNA viruses like SARS-CoV-2 and Influenza A virus (IAV) necessitates the continuous development of effective, safe, broadly acting, and generally accessible antiviral agents. Current treatments often face limitations such as early administration requirements, resistance development, and limited global access. Natural products, like European black elderberry (Sambucus nigra L.; S. nigra) fruit extract and quinine, have been used historically against viral infections. In this study, we investigated the antiviral efficacy of a standardized black elderberry fruit extract containing 3.2% anthocyanins (EC 3.2) and, as a second natural antiviral product, quinine, against IAV and SARS-CoV-2 in vitro. Methods: Madin–Darby Canine Kidney II (MDCKII) cells were infected with IAV PR-8, while human Calu-3 lung epithelial cells were infected with Wuhan-type SARS-CoV-2. Cells were treated with varying concentrations of EC 3.2 and quinine either as mono- or combinational therapy. Viral replication was assessed using quantitative RT-PCR, and cell viability was evaluated using WST-1 assays. Results: Our results demonstrate, for the first time, that both EC 3.2 and quinine individually inhibited IAV replication in a dose-dependent manner, with IC₅₀ values of approximately 1:400 for EC 3.2 and 250 nM for quinine. Most importantly, the combinational treatment exhibited a strong synergistic antiviral effect, as confirmed by the Bliss independence model (synergy scores of 14.7 for IAV, and 27.8 for SARS-CoV-2), without affecting cell viability. Conclusions: These findings suggest that the combined use of black elderberry extract and quinine might serve as an effective antiviral strategy against IAV and SARS-CoV-2, particularly since the synergistic effect allows for lower doses of each product while retaining therapeutic efficacy. In summary, this combinational in vitro approach, when expanded to other respiratory RNA viruses and confirmed in clinical studies, has the potential to open a promising avenue for pandemic preparedness. Full article

Breast cancer presents significant global challenges, necessitating effective treatments to combat drug resistance and minimize chemotherapy side effects. This study evaluated the cytotoxic effects of U-359, Oxaliplatin (Ox), and 5-Fluorouracil (5-FU) in MCF-7 and MCF-10A cells using MTT and RealTime-GLO assays. Morphological changes were assessed by light microscopy following Wright–Giemsa staining. Apoptosis induction was studied using qPCR for apoptotic markers, the RealTime-Glo™ Annexin V assay, and the cleaved PARP1 ELISA assay. Caspase 8 and 9 activities, ABCB1, ABCG2, and NF-κB protein levels were quantified using ELISA. Synergy was analyzed using the Bliss Independence Model. The results indicated that combining U-359 with Ox and 5-FU enhanced cytotoxicity compared to individual treatments. U-359 induced apoptosis-associated morphological changes in MCF-7 cells, which were augmented with the Ox and 5-FU treatment. Apoptosis assays confirmed the up-regulation of pro-apoptotic markers and the down-regulation of anti-apoptotic markers with U-359 alone or in combination. Elevated cleaved PARP1 levels suggested robust apoptosis induction with U-359 and Ox or 5-FU. Caspase activity assays demonstrated a significant activation of caspase 8 and 9, implicating both apoptotic pathways. Furthermore, U-359 down-regulated ABCB1, ABCG2, and NF-κB in MCF-7 cells, which were up-regulated by Ox and 5-FU alone. The Bliss Independence Model revealed strong synergistic interactions (SI < 1) between U-359 and Ox or 5-FU, particularly in reducing ABCB1 and NF-κB levels. U-359 combined with Ox and 5-FU shows potential for overcoming chemotherapy resistance in breast cancer by enhancing apoptosis and modulating drug resistance. Further clinical studies are needed to optimize treatment and improve outcomes. Full article

Invasive candidiasis is a common fungal infection associated with multiple risk factors, such as cancer, neutropenia, corticosteroid therapy, catheterization, and the use of broad-spectrum antibiotic treatment. Candida albicans is the predominant causative agent, although other Candida species have been emerging in the last years, together with a rise in a number of strains resistant to the currently available antifungal drugs, which poses a challenge when treating these infections. Drug repurposing and drug combinations are promising strategies for the treatment of invasive mycoses. In this study, we evaluated the effect of the combination of fluconazole (FLZ) and cyclosporine A (CsA) against 39 clinical isolates and reference strains of Candida. Two methods, the Loewe additivity model and Bliss independence model, were used to assess the antifungal activity of the drug combination according to CLSI and EUCAST guidelines. The results demonstrated a synergistic effect between fluconazole (FLZ) and cyclosporine A (CsA) against 15–17 Candida isolates, depending on the evaluation model used, including FLZ-resistant strains of C. albicans, C. glabrata, C. parapsilosis, and C. tropicalis. Notably, the combination significantly reduced the minimum inhibitory concentration (MIC) of FLZ in a substantial number of isolates, including those with resistance to FLZ. Additionally, time–kill curve studies confirmed the synergistic interaction, further validating the potential of this combination as an alternative therapeutic strategy for candidiasis treatment. These findings emphasize the importance of investigating innovative drug combinations to address the challenges posed by antifungal resistance and improve treatment options for invasive fungal infections. Full article

Background: Chemoresistance is a major obstacle in high-grade serous carcinoma (HGSC) treatment. Although many patients initially respond to chemotherapy, the majority of them relapse due to Carboplatin and Paclitaxel resistance. Drug repurposing has surfaced as a potentially effective strategy that works synergically with standard chemotherapy to bypass chemoresistance. In a prior study, using 2D cultures and two HGSC chemoresistant cell lines, it was demonstrated that combining Carboplatin or Paclitaxel with Pitavastatin or Ivermectin resulted in the most notable synergy. Acknowledging that 2D culture systems are limited in reflecting the tumor architecture, 3D cultures were generated to provide insights on treatment efficacy tests in more complex models. Objectives: We aimed to investigate whether combining Carboplatin or Paclitaxel with Pitavastatin or Ivermectin offers therapeutic benefits in a Cultrex-based 3D model. Methods: Here, the cytotoxicity of Carboplatin and Paclitaxel, both alone and in combination with Pitavastatin or Ivermectin, were analyzed on two chemoresistant tumor cell lines, OVCAR8 and OVCAR8 PTX R C, in 3D cultures. Cellular viability was assessed using CellTiter-Glo^® Luminescent assays. Also, it explored synergistic interactions using zero interaction potency, Loewe, Bliss independence, and High-single agent reference models. Results: Our research indicates combining chemotherapeutic drugs with Pitavastatin or Ivermectin yields significantly more cytotoxic effects than chemotherapy alone. For all the combinations tested, at least one model indicated an additive effect; however, only the combination of Paclitaxel and Ivermectin consistently demonstrated an additive effect across all chemoresistant cell lines cultured in 3D models, as well as in all four synergy reference models used to assess drug interactions. Conclusions: Combining Paclitaxel with Ivermectin has the highest cytotoxic and the strongest additive effect for both chemoresistant cell lines compared to Paclitaxel alone. Full article

Background: Plant derived isolated compounds or extracts enjoy great popularity among cancer patients, although knowledge about their mode of action is unclear. The present study investigated whether the combination of two herbal drugs, the cyanogenic diglucoside amygdalin and the isothiocyanate sulforaphane (SFN), influences growth and proliferation of renal cell carcinoma (RCC) cell lines. Methods: A498, Caki-1, and KTCTL-26 cells were exposed to low-dosed amygdalin (1 or 5 mg/mL), or SFN (5 µM) or to combined SFN-amygdalin. Tumor growth and proliferation were analyzed by MTT, BrdU incorporation, and clone formation assays. Cell cycle phases and cell cycle-regulating proteins were analyzed by flow cytometry and Western blotting, respectively. The effectiveness of the amygdalin–SFN combination was determined using the Bliss independence model. Results: 1 mg/mL amygdalin or 5 µM SFN, given separately, did not suppress RCC cell growth, and 5 mg/mL amygdalin only slightly diminished A498 (but not Caki-1 and KTCTL-26) cell growth. However, already 1 mg/mL amygdalin potently inhibited growth of all tumor cell lines when combined with SFN. Accordingly, 1 mg/mL amygdalin suppressed BrdU incorporation only when given together with SFN. Clonogenic growth was also drastically reduced by the drug combination, whereas only minor effects were seen under single drug treatment. Superior efficacy of co-treatment, compared to monodrug exposure, was also seen for cell cycling, with an enhanced G0/G1 and diminished G2/M phase in A498 cells. Cell cycle regulating proteins were altered differently, depending on the applied drug schedule (single versus dual application) and the RCC cell line, excepting phosphorylated Akt which was considerably diminished in all three cell lines with maximum effects induced by the drug combination. The Bliss independence analysis verified synergistic interactions between amygdalin and SFN. Conclusions: These results point to synergistic effects of amygdalin and SFN on RCC cell growth and clone formation and Akt might be a relevant target protein. The combined use of low-dosed amygdalin and SFN could, therefore, be beneficial as a complementary option to treat RCC. To evaluate clinical feasibility, the in vitro protocol must be applied to an in vivo model. Full article

Antimicrobial tolerance is a significant concern in the food industry, as it poses risks to food safety and public health. To overcome this challenge, synergistic combinations of antimicrobials have emerged as a potential solution. In this study, the combinations of two essential oil constituents (EOCs), namely carvacrol (CAR) and eugenol (EUG), with the quaternary ammonium compounds (QACs) benzalkonium chloride (BAC) and didecyldimethylammonium chloride (DDAC) were evaluated for their antimicrobial effects against Escherichia coli and Bacillus cereus, two common foodborne bacteria. The checkerboard assay was employed to determine the fractional inhibitory concentration index (FICI) and the fractional bactericidal concentration index (FBCI), indicating the presence of bactericidal, but not bacteriostatic, synergy in all QAC–EOC combinations. Bactericidal synergism was clearly supported by Bliss independence analysis. The bactericidal activity of the promising synergistic combinations was further validated by time–kill curves, achieving a >4-log₁₀ reduction of initial bacterial load, which is significant compared to typical industry standards. The combinations containing DDAC showed the highest efficiency, resulting in the eradication of bacterial population in less than 2–4 h. These findings emphasize the importance of considering both bacteriostatic and bactericidal effects when evaluating antimicrobial combinations and the potential of EOC–QAC combinations for sanitization and disinfection in the food industry. Full article

The role of the epidermal growth factor receptor (EGFR) in tumor progression and survival is often underplayed. Its expression and/or dysregulation is associated with disease advancement and poor patient outcome as well as drug resistance in breast cancer. EGFR is often overexpressed in breast cancer and particularly triple-negative breast cancer (TNBC), which currently lacks molecular targets. We examined the synergistic potential of an EGFR inhibitor (EGFRi) in combination with doxorubicin (Dox) in estrogen-positive (ER+) MCF-7 and MDA-MB-231 TNBC cell lines. The exposure of MDA-MB-231 and MCF-7 to EGFRi produced an IC_50s of 6.03 µM and 3.96 µM, respectively. Dox induced MDA-MB-231 (IC₅₀ 9.67 µM) and MCF-7 (IC₅₀ 1.4 µM) cytotoxicity. Combinations of EGFRi-Dox significantly reduced the IC₅₀ in MCF-7 (0.46 µM) and MBA-MB 231 (0.01 µM). Synergistic drug interactions in both cell lines were confirmed using the Bliss independence model. Pro-apoptotic Caspase-3/7 activation occurred in MCF-7 at 0.1–10 µM of EGFRi and Dox single treatments, whilst 1 μM Dox yielded a more potent effect on MDA-MB-231. EGFRi and Dox individually and in combination downregulated the EGFR gene expression in MCF-7 and MDA-MB-231 (p < 0.001). This study demonstrates EGFRi’s potential for eliciting synergistic interactions with Dox, causing enhanced growth inhibition, apoptosis induction, and downregulation of EGFR in both cell lines. Full article

The in vitro/in vivo correlation of antifungal combination testing is necessary in order to assess the efficacy of combination regimens. We, therefore, attempted to correlate in vitro chequerboard testing of posaconazole (POS) and amphotericin B (AMB) with the in vivo outcome of combination therapy against experimental candidiasis in a neutropenic murine model. The AMB + POS combination was tested against a Candida albicans isolate. In vitro, a broth microdilution 8 × 12 chequerboard method with serial two-fold drug dilutions was used. In vivo, CD1 female neutropenic mice with experimental disseminated candidiasis were treated with i.p. AMB and p.o. POS alone and in combination at three effective doses (ED20, ED50 and ED80 corresponding to 20%, 50% and 80% of maximal effect, respectively). CFU/kidneys after 2 days were determined. The pharmacodynamic interactions were assessed based on Bliss independence interaction analysis. In vitro, a Bliss antagonism of −23% (−23% to −22%) was observed at 0.03–0.125 mg/L of AMB with 0.004–0.015 mg/L of POS, while a Bliss synergy of 27% (14%–58%) was observed at 0.008–0.03 mg/L of AMB with 0.000015–0.001 mg/L of POS. In vivo, Bliss synergy (13 ± 4%) was found when an AMB ED20 of 1 mg/kg was combined with all POS ED 0.2–0.9 mg/kg, while Bliss antagonism (35–83%) was found for the combinations of AMB ED50 2 mg/kg and ED80 3.2 mg/kg with POS ED80 of 0.9 mg/kg. Free drug serum levels of POS and AMB in in vivo synergistic and antagonistic combinations were correlated with the in vitro synergistic and antagonistic concentrations, respectively. Both synergistic and antagonistic interactions were found for the AMB + POS combination. POS compromised the efficacy of high effective AMB doses and enhanced low ineffective AMB doses. In vitro concentration-dependent interactions were correlated with in vivo dose-dependent interactions of the AMB + POS combination. In vivo interactions occurred at free drug serum levels close to in vitro interacting concentrations. Full article

In the context of the Atmosphere Observing System (AOS) international program, a new-generation spaceborne lidar is expected to be in polar orbit for deriving new observations of aerosol and clouds. In this work, we analyze the added values of these new observations for characterizing aerosol vertical distribution. For this, synthetic observations are simulated using the BLISS lidar simulator in terms of the backscatter coefficient at 532 nm. We consider two types of lidar instruments, an elastic backscatter lidar instrument and a high spectral resolution lidar (HSRL). These simulations are performed with atmospheric profiles from a nature run (NR) modeled by the MOCAGE chemical transport model. In three case studies involving large events of different aerosol species, the added value of the HSRL channel (for measuring aerosol backscatter profiles with respect to simple backscatter measurements) is shown. Observations independent of an a priori lidar ratio assumption, as done typically for simple backscattering instruments, allow probing the vertical structures of aerosol layers without divergence, even in cases of intense episodes. A 5-day study in the case of desert dust completes the study of the added value of the HSRL channel with relative mean bias from the NR of the order of 1.5%. For low abundances, relative errors in the backscatter coefficient profiles may lay between +40% and −40%, with mean biases between +5% and −5%. Full article