Global Results of Implantable Loop Recorder for Detection of Atrial Fibrillation After Stroke: Reveal LINQ Registry.

BACKGROUND: We aimed to quantify the incidence of atrial fibrillation (AF) in patients with cryptogenic stroke globally, as well as separately in patients in and outside of Japan, using an implantable loop recorder from a prospective, observational, Reveal LINQ Registry. METHODS AND RESULTS: Patients developing cryptogenic stroke and monitored by implantable loop recorder for searching AF were studied. The primary end point was incidence of AF within 36 months after insertion. Secondary end points were recurrent ischemic stroke/transient ischemic attack and AF-related treatment strategies. A total of 271 patients (61.6±14.3 years, 170 men, 60 from Japan) were enrolled from 12 countries. AF was detected in 28.2% at 36 months. The median time from enrollment to AF detection was 7.9 months. During the first 12 months, the AF detection rate slope was relatively steeper in the Japanese subgroup versus non-Japanese patients. However, by 3 years, the cumulative incidence of AF detection did not differ between groups. Age was the only variable associated with AF detection (hazard ratio, 1.05 [95% CI, 1.02-1.07] per year), trending higher in older age groups. Of the 271 patients, 11 (4.1%) developed recurrent ischemic stroke/transient ischemic attack; AF was detected by implantable loop recorder in only 1 of these patients. Patients with detected AF were more commonly taking oral anticoagulation than those without AF at the last follow-up (64.7% versus 25.3%, P<0.001). CONCLUSIONS: The rate of AF detection was similar to other studies in stroke populations monitored by implantable loop recorders, including CRYSTAL-AF (Cryptogenic Stroke and Underlying Atrial Fibrillation), STROKE-AF (Stroke of Unknown Cause and Underlying Atrial Fibrillation) and PER-DIEM (Post-Embolic Rhythm Detection With Implantable Versus External Monitoring). Patients with detected AF more commonly initiated anticoagulation than those without AF.

Azamollugin, a mollugin derivative, has inhibitory activity on MyD88- and TRIF-dependent pathways.

Previously, we reported that azamollugin, an aza-derivative of mollugin, exhibited potent inhibitory activity on NO production in LPS-stimulated RAW 264.7 cells. Further investigations in this study revealed that azamollugin not only suppressed iNOS gene expression regulated by NF-κB, but also inhibited LPS-induced IFN-ß expression, which is known to be regulated by IRF3. Azamollugin exhibited an inhibitory activity on LPS-induced IRAK1 activation, suggesting inhibitory effect on the MyD88-dependent pathway. Furthermore, azamollugin inhibited LPS-induced phosphorylation of IRF3 and its upstream factor, TBK1/IKKε, suggesting an inhibitory effect on the TRIF-dependent pathway via TLR4. In addition, azamollugin also suppressed poly(I:C)-induced phosphorylation of TBK1 and IRF3, suggesting an inhibitory effect on the TRIF-dependent pathway via TLR3. These results suggest that azamollugin has inhibitory activity against both the MyD88-dependent and TRIF-dependent pathways, respectively.

Late gadolinium enhancement in early repolarization syndrome.

BACKGROUND: In patients with Brugada syndrome, myocardial fibrosis can be identified through epicardial biopsy or cardiac magnetic resonance (CMR) imaging with late gadolinium enhancement (LGE). However, the myocardial alterations in patients with early repolarization syndrome (ERS) remain poorly elucidated. OBJECTIVE: The objective of this study was to investigate the presence of myocardial fibrosis in patients with ERS by LGE in CMR. METHODS: We retrospectively evaluated 20 patients with ERS, all of whom exhibited J waves in the contiguous 2 leads. The location of J waves was classified as in the septum (V1-V2), anterior (V3-V4), lateral (I, aVL, V5-V6), inferior (II, III, aVF), or posterior (V7-V9) regions. To compare the distribution of LGE on CMR imaging with J waves, sections on short-axis view of the left ventricle (LV) were categorized as located in the septum, anterior, lateral, inferior, and posterior regions. RESULTS: Overall, 85% of ERS patients displayed LGE, which was more prevalent in the septum and posterior regions, followed by the inferior and lateral regions. The presence or absence of J waves and LGE coincided in 61% of LV areas, whereas discordance between the distributions of J waves and LGE was observed in 38%. LGE was most frequent in the septum (75%), where its reflection in J waves may be less robust. The appearance of LGE was not associated with symptoms, electrical storm, or ventricular fibrillation occurrence during follow-up. CONCLUSION: LGE is common in patients with ERS, and the distribution of J waves and LGE coincides in approximately 60% of LV areas.

Impact of extracardiac sarcoidosis on clinical outcomes in patients with cardiac sarcoidosis: Importance of continued screening for cardiac involvement.

BACKGROUND: The prognostic impact of extracardiac sarcoidosis remains unknown in cardiac sarcoidosis (CS). We aimed to evaluate the influence of extracardiac sarcoidosis on clinical outcomes and the effect of continued outpatient visits for screening of cardiac involvement. METHODS: Ninety-nine patients with CS were divided into two groups: patients with systemic CS who had prior extracardiac sarcoidosis, patients with isolated CS who had no prior extracardiac sarcoidosis. Patients with systemic CS were divided according to the continuation of outpatient visits. The endpoint was cardiac death, fatal ventricular arrhythmia, or hospitalization for heart failure. RESULTS: At the time of diagnosing CS, patients with isolated CS had a higher prevalence of high-grade atrioventricular block or fatal ventricular arrhythmia, and left ventricular contractile dysfunction than those with systemic CS. Over a median follow-up of 42 months, cardiac events occurred in 19 (37%) of 52 patients with systemic CS and in 27 (57%) of 47 patients with isolated CS. The event-free survival rate was worse in patients with isolated CS than in those with systemic CS. Cox proportional hazard analysis showed that the absence of prior extracardiac sarcoidosis was an independent predictor of adverse outcomes. Patients with systemic CS who ceased outpatient visits had a lower left ventricular ejection fraction with severe heart failure symptoms and a worse event-free survival rate than those who continued outpatient visits. CONCLUSIONS: The presence of extracardiac sarcoidosis is associated with clinical outcomes. The cessation of screening for cardiac involvement after diagnosing extracardiac sarcoidosis is associated with adverse outcomes.

Artificial intelligence to detect noise events in remote monitoring data.

Background: Remote monitoring (RM) of cardiac implantable electrical devices (CIEDs) can detect various events early. However, the diagnostic ability of CIEDs has not been sufficient, especially for lead failure. The first notification of lead failure was almost noise events, which were detected as arrhythmia by the CIED. A human must analyze the intracardiac electrogram to accurately detect lead failure. However, the number of arrhythmic events is too large for human analysis. Artificial intelligence (AI) seems to be helpful in the early and accurate detection of lead failure before human analysis. Objective: To test whether a neural network can be trained to precisely identify noise events in the intracardiac electrogram of RM data. Methods: We analyzed 21 918 RM data consisting of 12 925 and 1884 Medtronic and Boston Scientific data, respectively. Among these, 153 and 52 Medtronic and Boston Scientific data, respectively, were diagnosed as noise events by human analysis. In Medtronic, 306 events, including 153 noise events and randomly selected 153 out of 12 692 nonnoise events, were analyzed in a five-fold cross-validation with a convolutional neural network. The Boston Scientific data were analyzed similarly. Results: The precision rate, recall rate, F1 score, accuracy rate, and the area under the curve were 85.8 ± 4.0%, 91.6 ± 6.7%, 88.4 ± 2.0%, 88.0 ± 2.0%, and 0.958 ± 0.021 in Medtronic and 88.4 ± 12.8%, 81.0 ± 9.3%, 84.1 ± 8.3%, 84.2 ± 8.3% and 0.928 ± 0.041 in Boston Scientific. Five-fold cross-validation with a weighted loss function could increase the recall rate. Conclusions: AI can accurately detect noise events. AI analysis may be helpful for detecting lead failure events early and accurately.

Demonstration of Arrhythmia Substrate-Associated Dispersion of Repolarization by Epicardial Unipolar Mapping in Brugada Syndrome.

BACKGROUND: Epicardial unipolar mapping has not been thoroughly investigated in Brugada syndrome (BrS). OBJECTIVES: This study aims to examine the characteristics of epicardial unipolar potentials in BrS and investigate the differences from overt cardiomyopathy. METHODS: Epicardial mapping was performed in 8 patients with BrS and 6 patients with cardiomyopathy. We investigated the J-wave amplitudes using unipolar recordings at delayed potential (DP) sites via bipolar recordings. The repolarization time (RT) at and around the DP recording sites was measured, and maximum dispersion of the RT divided by the distance was defined as the RT dispersion index. RESULTS: Epicardial mapping at baseline revealed significantly higher J-wave amplitude with bipolar DP in patients with BrS than in patients with cardiomyopathy. J-wave amplitude ≥0.42 mV had 99.1% sensitivity and 100% specificity for diagnosing BrS. The RT dispersion index was significantly higher in patients with BrS than in patients with cardiomyopathy at baseline. In all patients with BrS, coved-type unipolar electrograms without negative T waves (short RT) appeared close to coved-type electrograms with negative T waves (long RT) at the DP recording sites after pilsicainide administration. Thus, a steep RT dispersion was observed in this region, and ventricular arrhythmias emerged from this shorter RT area in all 3 patients with BrS in whom ventricular arrhythmias were induced. CONCLUSIONS: Bipolar DP-related prominent unipolar J waves and steep repolarization gradients may be more specific for characterizing BrS than for overt cardiomyopathy. Ventricular arrhythmias in BrS are associated with a steep repolarization gradient, indicating phase 2 re-entry as a possible cause.

Mode and Characteristics of Arrhythmia Initiation in Idiopathic Ventricular Fibrillation: A THESIS Substudy.

BACKGROUND: There is limited information on the mode of arrhythmia initiation in idiopathic ventricular fibrillation (IVF). A non-pause-dependent mechanism has been suggested to be the rule. OBJECTIVES: The aim of this study was to assess the mode and characteristics of initiation of polymorphic ventricular tachycardia (PVT) in patients with short or long-coupled PVT/IVF included in THESIS (THerapy Efficacy in Short or long-coupled idiopathic ventricular fibrillation: an International Survey), a multicenter study involving 287 IVF patients treated with drugs or radiofrequency ablation. METHODS: We reviewed the initiation of 410 episodes of ≥1 PVT triplet in 180 patients (58.3% females; age 39.6 ± 13.6 years) with IVF. The incidence of pause-dependency arrhythmia initiation (prolongation by >20 ms of the preceding cycle length) was assessed. RESULTS: Most arrhythmias (n = 295; 72%) occurred during baseline supraventricular rhythm without ambient premature ventricular complexes (PVCs), whereas 106 (25.9%) occurred during baseline rhythm including PVCs. Nine (2.2%) arrhythmias occurred during atrial/ventricular pacing and were excluded from further analysis. Mode of PVT initiation was pause-dependent in 45 (15.6%) and 64 (60.4%) of instances in the first and second settings, respectively, for a total of 109 of 401 (27.2%). More than one type of pause-dependent and/or non-pause-dependent initiation (mean: 2.6) occurred in 94.4% of patients with ≥4 events. Coupling intervals of initiating PVCs were <350 ms, 350-500 ms, and >500 ms in 76.6%, 20.72%, and 2.7% of arrhythmia initiations, respectively. CONCLUSIONS: Pause-dependent initiation occurred in more than a quarter of arrhythmic episodes in IVF patients. PVCs having long (between 350 and 500 ms) and very long (>500 ms) coupling intervals were observed at the initiation of nearly a quarter of PVT episodes.

Risk stratification for the occurrence of ventricular fibrillation in patients with early repolarization syndrome.

BACKGROUND: Several signs of malignant early repolarizations have been proposed in patients with early repolarization syndrome (ERS). However, reports have challenged the efficacy of these signs in predicting future ventricular fibrillation (VF) in patients with ERS. OBJECTIVE: This study aimed to assess the predictive value of various electrocardiogram (ECG) markers for future VF events in patients with ERS. METHODS: We retrospectively evaluated the clinical characteristics of 44 patients with ERS to identify risk factors for VF during follow-up. RESULTS: After the initial event, 16 patients experienced VF (VF group), whereas 28 did not (non-VF group). The VF group had a longer QRS interval, more fragmented QRS (fQRS), and a higher T/R voltage ratio than the non-VF group. Wide J waves were more prevalent in the VF group; however, other J-wave markers did not differ between the groups. Positive late potentials recorded on signal-averaged ECGs were more frequent in the VF group. Whereas none of the patients showed spontaneous Brugada syndrome on ECG, the VF group frequently exhibited pilsicainide-induced ST-segment elevation. These ECG markers were significantly associated with the occurrence of VF during follow-up. Patients with multiple ECG factors, including QRS abnormalities (wide QRS or fQRS), wide J waves, and a high T/R ratio, had a worse prognosis than patients without multiple factors, effectively stratifying patient risk. CONCLUSION: The occurrence of VF in patients with ERS may be associated with conduction abnormalities such as QRS widening, fQRS, high T/R ratio, positive late potentials, and pilsicainide test results. Therefore, ECG factors could be useful in identifying high-risk patients.

Brugada syndrome in Japan and Europe: a genome-wide association study reveals shared genetic architecture and new risk loci.

BACKGROUND AND AIMS: Brugada syndrome (BrS) is an inherited arrhythmia with a higher disease prevalence and more lethal arrhythmic events in Asians than in Europeans. Genome-wide association studies (GWAS) have revealed its polygenic architecture mainly in European populations. The aim of this study was to identify novel BrS-associated loci and to compare allelic effects across ancestries. METHODS: A GWAS was conducted in Japanese participants, involving 940 cases and 1634 controls, followed by a cross-ancestry meta-analysis of Japanese and European GWAS (total of 3760 cases and 11 635 controls). The novel loci were characterized by fine-mapping, gene expression, and splicing quantitative trait associations in the human heart. RESULTS: The Japanese-specific GWAS identified one novel locus near ZSCAN20 (P = 1.0 × 10-8), and the cross-ancestry meta-analysis identified 17 association signals, including six novel loci. The effect directions of the 17 lead variants were consistent (94.1%; P for sign test = 2.7 × 10-4), and their allelic effects were highly correlated across ancestries (Pearson's R = .91; P = 2.9 × 10-7). The genetic risk score derived from the BrS GWAS of European ancestry was significantly associated with the risk of BrS in the Japanese population [odds ratio 2.12 (95% confidence interval 1.94-2.31); P = 1.2 × 10-61], suggesting a shared genetic architecture across ancestries. Functional characterization revealed that a lead variant in CAMK2D promotes alternative splicing, resulting in an isoform switch of calmodulin kinase II-δ, favouring a pro-inflammatory/pro-death pathway. CONCLUSIONS: This study demonstrates novel susceptibility loci implicating potentially novel pathogenesis underlying BrS. Despite differences in clinical expressivity and epidemiology, the polygenic architecture of BrS was substantially shared across ancestries.

Effects of Combination Therapy with Intravitreal Ranibizumab and Tissue Plasminogen Activator for Neovascular Age-Related Macular Degeneration.

Background: Subretinal hyper-reflective material (SHRM) sometimes causes vision loss in spite of anti-vascular endothelial growth factor (VEGF) therapy in eyes with neovascular age-related macular degeneration (nvAMD). We evaluated the impacts of combination therapy with intravitreal ranibizumab (IVR) and tissue plasminogen activator (tPA) in eyes with nvAMD accompanying SHRM. Methods: In total, 25 eyes of 25 patients (16 men and 9 women, 76.7 years old), who underwent IVR/tPA for nvAMD with SHRM and were followed up for at least 12 months, were retrospectively reviewed. In total, 15 eyes were treatment-naïve and 10 eyes had previous treatment for nvAMD. Results: In total, 16 eyes had type 2 macular neovascularization (MNV), 5 eyes type 1 MNV with fibrovascular pigment epithelial detachment and 4 eyes polypoidal choroidal vasculopathy. At month 12, SHRM regressed or reduced in 18 eyes (72%) and the best-corrected visual acuity (BCVA) improved in 6 eyes (24%) and was unchanged in 14 eyes (56%), while the mean BCVA was just stabilized. The mean central retinal thickness, macular volume and SHRM thickness significantly improved from 408 µm to 287 µm, from 11.9 mm3 to 9.6 mm3, from 369 µm to 165 µm, respectively (p < 0.01). Conclusions: The combination therapy with IVR/tPA for nvAMD with SHRM may help preserve vision by prompt regression of SHRM.

Electrical stimulation of the lower eyelid orbicularis oculi muscle improves periocular dark circles.

BACKGROUND: We developed and tested the safety and efficacy of a cosmetic device to improve dark circles using electrical muscle stimulation of the orbicularis oculi muscle. METHODS: Overall, 18 participants (36 eyes) were studied. The following five items were evaluated before and after the intervention:(1) the Clinical Dark Circle Score using clinical findings and photographs, (2) transcutaneous oxygen partial pressure (TcPO2) on the lower eyelid, (3) thermography, (4) two-dimensional laser blood flowmetry, and (5) spectrophotometry. RESULTS: The mean score at baseline was 2.0 ± 0.90 (mean ± standard deviation), and that at the end of the study was 1.2 ± 1.0 (Wilcoxon signed-rank sum test, p < 0.0001), indicating a significant reduction. The spectrophotometer showed a significant decrease in a* and L* values before and after use (Wilcoxon signed-rank sum test, p < 0.0001). There was also a weak negative correlation between the change in score and the change in blood flow and TcPO2 measured using a laser perfusion device (Spearman's rank correlation coefficient, r = -0.32 and -0.39, respectively). Stratified analysis of the baseline score showed a strong negative correlation between the change in score and the change in spectrophotometric a* in the subjects/group with mild periocular dark circles (Spearman's rank correlation coefficient, r = -0.46). Contrastingly, no correlation was observed for any of the measurements in the subjects/group with severe periocular dark circles. After 1 month, no device-related ophthalmic adverse events were observed in any of the participants. CONCLUSION: Electrical muscle stimulation could improve periocular dark circles, especially in the subjects/group with mild periocular dark circles, and was safe.

Vincarostine A, a novel anti-malarial trimeric monoterpenoid indole alkaloid from Catharanthus roseus.

A novel trimeric monoterpenoid indole alkaloid, vincarostine A (1) consisting of an aspidosperma-iboga-aspidosperma type skeleton, was isolated from the whole plant of Catharanthus roseus. The structure including absolute stereochemistry was elucidated on the basis of 2D NMR data and CD spectrum. Vincarostine A (1) showed anti-malarial activity.

Oxomollugin, an oxidized substance in mollugin, inhibited LPS-induced NF-κB activation via the suppressive effects on essential activation factors of TLR4 signaling.

Oxomollugin is a degraded product of mollugin and was found to be an active compound that inhibits LPS-induced NF-κB activation. In this study, we investigated the inhibitory activity of oxomollugin, focusing on TLR4 signaling pathway, resulting in NF-κB activation. Oxomollugin inhibited the LPS-induced association of essential factors for initial activation of TLR4 signaling, MyD88, IRAK4 and TRAF6. Furthermore, oxomollugin showed suppressive effects on LPS-induced modification of IRAK1, IRAK2 and TRAF6, LPS-induced association of TRAF6-TAK1/TAB2, and followed by IKKα/ß phosphorylation, which critical in signal transduction leading to LPS-induced NF-κB activation. The consistent results suggested that oxomollugin inhibits LPS-induced NF-κB activation via the suppression against signal transduction in TLR4 signaling pathway.The activities of oxomollugin reported in this study provides a deeper understanding on biological activity of mollugin derivatives as anti-inflammatory compounds.

Increased skeletal muscle mass index was involved in glycemic efficacy following diabetes treatment, and changes in fat mass index correlated with the changes in the lipid ratio in type 2 diabetes.

AIM: This study aimed to investigate the association between changes in body composition, glycated hemoglobin, and lipid ratio during the treatment of patients with type 2 diabetes mellitus (T2DM). METHODS: This retrospective analysis used data from outpatients with T2DM who had confirmed body composition and measured laboratories at administration and after treatment. The baseline characteristics and prescribed treatment were collected. The total cholesterol/high-density lipoprotein cholesterol (HDL) ratio, low-density lipoprotein cholesterol (LDL)/HDL ratio, and triglyceride-glucose (TyG) index were also calculated. RESULTS: A total of 207 patients (mean patient age, 62.0 ± 13.7 years; 68.1 % males) were enrolled. Fat mass index (FMI) changes correlated with the changes in the lipid ratio, whereas skeletal muscle mass index (SMI) changes inversely correlated with glycated hemoglobin (HbA1c) changes. Multiple regression analysis showed that changes in LDL/HDL and TyG correlated with FMI changes (t = 2.388, p = 0.017, t = 2.022, p = 0.044). Conversely, HbA1c changes correlated with SMI changes (t = -2.552, p = 0.011). CONCLUSION: In patients with T2DM, increased SMI was involved in glycemic efficacy, and FMI changes were associated with LDL/HDL and TyG.

Vincazalidine A, a unique bisindole alkaloid from Catharanthus roseus.

A new dimeric indole alkaloid, vincazalidine A consisting of an aspidosperma type and a modified iboga type with 1-azatricyclo ring system consisting of one azepane and two piperidine rings coupled with an oxazolidine ring was isolated from Catharanthus roseus, and the structure including absolute stereochemistry was elucidated on the basis of spectroscopic data as well as DP4 statistical analysis. Vincazalidine A induced G2 arrest and subsequent apoptosis in human lung carcinoma cell line, A549 cells.

Expert consensus document on automated diagnosis of the electrocardiogram: The task force on automated diagnosis of the electrocardiogram in Japan part 3: Inappropriate internal processing in the automatic diagnosis of electrocardiograms and its problems.

Computer diagnosis of electrocardiograms is widely used to provide useful information in clinical practice and medical checkups. However, it is common for users to be confused by the inappropriate diagnosis. We illustrate some examples of inappropriate automatic diagnoses and discuss the actual situation of inappropriate automatic processing and its problems.

Local dispersion of repolarization in the occurrence of ventricular fibrillation in Brugada syndrome: Possibility of phase 2 reentry?

To date, there have been no reports of recording epicardial electrograms at the onset of spontaneous ventricular fibrillation (VF) in patients with Brugada syndrome (BrS). In the case of BrS, unipolar and bipolar electrogram recording on the right ventricular epicardium revealed that dispersion of repolarization with delayed potential was associated with spontaneous occurrence of VF. Phase 2 reentry associated with shortening and dispersion of action potential could have been recorded for the first time in BrS. Epicardial unipolar mapping can guide accurate and appropriate ablation for the elimination of arrhythmia substrate in J wave syndrome.

Clinical characteristics of electrical storm in patients with early repolarization syndrome.

BACKGROUND: Early repolarization syndrome (ERS) is an idiopathic ventricular fibrillation (VF) associated with inferolateral J waves. While electrical storm (ES) in ERS is not rare, their characteristics and risk factors are not fully understood. OBJECTIVE: This study aimed to clarify the significance of ES in ERS. METHODS: We evaluated 44 patients with ERS who experienced VF/sudden cardiac death or arrhythmic syncope. We assessed clinical characteristics to identify the risk factors for ES. RESULTS: In total, 13 patients (30%) experienced ES (ES group). Of these, 11 patients (85%) experienced ES during the acute phase of initial VF episodes and 2 patients (2%) experienced ES during follow-up. VF associated with ES occurred during therapeutic hypothermia in 6 of 13 patients (46%). The J-wave voltage during therapeutic hypothermia was higher in the ES group than that in the patients without ES. Isoproterenol was used in 5 patients (38%), which decreased J-wave voltage and relieved ES. Among the clinical markers, shorter QT and QTp intervals (the interval from QRS onset to the peak of T wave), pilsicainide-induced ST elevation, and high scores on the Shanghai Score System were associated with ES. Although pilsicainide induced ST elevation in 6 of 34 patients (18%), spontaneous Brugada electrocardiographic patterns did not appear to be associated with VF. Therapeutic hypothermia was also a risk factor for acute phase ES. CONCLUSION: Patients with ERS in the ES group frequently had short QT and QTp intervals, pilsicainide-induced ST elevations, and high Shanghai Score System scores. Therapeutic hypothermia was also associated with acute phase ES.

Ceramicines U-Z from Chisocheton ceramicus and structure-antimalarial activity relationship study.

Ceramicines are a series of limonoids which were isolated from the barks of Malaysian Chisocheton ceramicus (Meliaceae), and were known to show various biological activity. Six new limonoids, ceramicines U-Z (1-6), with a cyclopentanone[α]phenanthrene ring system with a ß-furyl ring at C-17 were isolated from the barks of C. ceramicus. Their structures were determined on the basis of the 1D and 2D NMR analyses, and their absolute configurations were investigated by CD spectroscopy. Ceramicine W (3) exhibited potent antimalarial activity against Plasmodium falciparum 3D7 strain with IC50 value of 1.2 µM. In addition, the structure-antimalarial activity relationship (SAR) of the ceramicines was investigated to identify substituent patterns that may enhance activity. It appears that ring B and the functional groups in the vicinity of rings B and C are critical for the antimalarial activity of the ceramicines. In particular, bulky ester substituents with equatorial orientation at C-7 and C-12 greatly increase the antimalarial activity.