Early intervention with azelastine nasal spray may reduce viral load in SARS-CoV-2 infected patients.

With the changing epidemiology of COVID-19 and its impact on our daily lives, there is still an unmet need of COVID-19 therapies treating early infections to prevent progression. The current study was a randomized, parallel, double-blind, placebo-controlled trial. Ninety SARS-CoV-2 positive patients were randomized into 3 groups receiving placebo, 0.02% or 0.1% azelastine nasal spray for 11 days, during which viral loads were assessed by quantitative PCR. Investigators assessed patients' status throughout the trial including safety follow-ups (days 16 and 60). Symptoms were documented in patient diaries. Initial viral loads were log10 6.85 ± 1.31 (mean ± SD) copies/mL (ORF 1a/b gene). After treatment, virus load was reduced in all groups (p < 0.0001) but was greater in the 0.1% group compared to placebo (p = 0.007). In a subset of patients (initial Ct < 25) viral load was strongly reduced on day 4 in the 0.1% group compared to placebo (p = 0.005). Negative PCR results appeared earlier and more frequently in the azelastine treated groups: being 18.52% and 21.43% in the 0.1% and 0.02% groups, respectively, compared to 0% for placebo on day 8. Comparable numbers of adverse events occurred in all treatment groups with no safety concerns. The shown effects of azelastine nasal spray may thus be suggestive of azelastine's potential as an antiviral treatment.Trial registration: The study was registered in the German Clinical Trial Register (DRKS-ID: DRKS00024520; Date of Registration in DRKS: 12/02/2021). EudraCT number: 2020-005544-34.

Pineapple Lectin AcmJRL Binds SARS-CoV-2 Spike Protein in a Carbohydrate-Dependent Fashion.

The highly glycosylated spike protein of SARS-CoV-2 is essential for infection and constitutes a prime target for antiviral agents and vaccines. The pineapple-derived jacalin-related lectin AcmJRL is present in the medication bromelain in significant quantities and has previously been described to bind mannosides. Here, we performed a large ligand screening of AcmJRL by glycan array analysis, quantified the interaction with carbohydrates and validated high-mannose glycans as preferred ligands. Because the SARS-CoV-2 spike protein was previously reported to carry a high proportion of high-mannose N-glycans, we tested the binding of AcmJRL to the recombinantly produced extraviral domain of spike protein. We could demonstrate that AcmJRL binds the spike protein with a low-micromolar KD in a carbohydrate-dependent fashion.

Pharmacometric Modeling of the Impact of Azelastine Nasal Spray on SARS-CoV-2 Viral Load and Related Symptoms in COVID-19 Patients.

The histamine-1 receptor antagonist azelastine was recently found to impact SARS-CoV-2 viral kinetics in a Phase 2 clinical trial (CARVIN). Thus, we investigated the relationship between intranasal azelastine administrations and viral load, as well as symptom severity in COVID-19 patients and analyzed the impact of covariates using non-linear mixed-effects modeling. For this, we developed a pharmacokinetic (PK) model for the oral and intranasal administration of azelastine. A one-compartment model with parallel absorption after intranasal administration described the PK best, covering both the intranasal and the gastro-intestinal absorption pathways. For virus kinetic and symptoms modeling, viral load and symptom records were gathered from the CARVIN study that included data of 82 COVID-19 patients receiving placebo or intranasal azelastine. The effect of azelastine on viral load was described by a dose-effect model targeting the virus elimination rate. An extension of the model revealed a relationship between COVID-19 symptoms severity and the number of infected cells. The analysis revealed that the intranasal administration of azelastine led to a faster decline in viral load and symptoms severity compared to placebo. Moreover, older patients showed a slower decline in viral load compared to younger patients and male patients experienced higher peak viral loads than females.

DNA Protection by an Aronia Juice-Based Food Supplement.

BACKGROUND: This study investigated the effects of an aronia juice-based food supplement on background and total DNA strand breaks in whole blood, and on H2O2-induced DNA strand breaks in isolated peripheral blood lymphocytes. METHODS: Ninety-one healthy volunteers were randomly selected to consume either the food supplement (2 × 25 mL drinking ampules, n = 45) or no supplement (n = 46) daily for eight weeks. RESULTS: Background DNA strand breaks decreased significantly after four and eight weeks of supplement consumption, compared to baseline (p < 0.05), but the overall effect was low, and neither group showed a decrease in total DNA strand breaks. Conversely, supplement consumption clearly reduced H2O2-induced DNA strand breaks ex vivo (p < 0.001), with statistically significant reductions after four and eight weeks, compared to the control group (p < 0.05). CONCLUSIONS: Thus, although consuming antioxidant supplements might produce only marginal immediate benefits under healthy conditions, potential preventive effects warrant further investigation.

Troxerutin flavonoid has neuroprotective properties and increases neurite outgrowth and migration of neural stem cells from the subventricular zone.

Troxerutin (TRX) is a water-soluble flavonoid which occurs commonly in the edible plants. Recent studies state that TRX improves the functionality of the nervous system and neutralizes Amyloid-ß induced neuronal toxicity. In this study, an in vitro assay based upon Neural stem cell (NSCs) isolated from the subventricular zone of the postnatal balb/c mice was established to explore the impact of TRX on individual neurogenesis processes in general and neuroprotective effect against ß-amyloid 1-42 (Aß42) induced inhibition in differentiation in particular. NSCs were identified exploiting immunostaining of the NSCs markers. Neurosphere clonogenic assay and BrdU/Ki67 immunostaining were employed to unravel the impact of TRX on proliferation. Differentiation experiments were carried out for a time span lasting from 48 h to 7 days utilizing ß-tubulin III and GFAP as neuronal and astrocyte marker respectively. Protective effects of TRX on Aß42 induced depression of NSCs differentiation were determined after 48 h of application. A neurosphere migration assay was carried out for 24 h in the presence and absence of TRX. Interestingly, TRX enhanced neuronal differentiation of NSCs in a dose-dependent manner after 48 h and 7 days of incubation and significantly enhanced neurite growth. A higher concentration of TRX also neutralized the inhibitory effects of Aß42 on neurite outgrowth and length after 48 h of incubation. TRX significantly stimulated cell migration. Overall, TRX not only promoted NSCs differentiation and migration but also neutralized the inhibitory effects of Aß42 on NSCs. TRX, therefore, offers an interesting lead structure from the perspective of drug design especially to promote neurogenesis in neurological disorders i.e. Alzheimer's disease.

Randomised trial on performance, safety and clinical benefit of hyaluronic acid, hyaluronic acid plus dexpanthenol and isotonic saline nasal sprays in patients suffering from dry nose symptoms.

OBJECTIVE: Limited data exist on the clinical benefits of nasal applications for moistening the nasal mucosa. We therefore investigated the effects of hyaluronic acid, hyaluronic acid plus dexpanthenol and isotonic saline nasal sprays in patients suffering from dry nose symptoms in an otorhinolaryngological outpatient setting. METHODS: 240 patients were randomised into this prospective, three-armed clinical trial with two assessment points (baseline and 4 weeks later). Patients received either hyaluronic acid, hyaluronic acid plus dexpanthenol or isotonic saline nasal spray over a period of four weeks. Rhinitis Sicca Symptom Score (RSSS) was assessed as primary endpoint, and individual symptoms and tolerability of all treatments as secondary endpoints. Patient perceptions after first application of the allocated nasal spray were recorded using the Nasal Spray Sensory Scale. Treatment effects were analysed for each study arm first and subsequently compared against each other. RESULTS: RSSS (hyaluronic acid: mean difference = 8.90 [98.33% CI = 7.34/10.45]; hyaluronic acid plus dexpanthenol: mean difference = 8.42 [98.33% CI = 6.91/9.94]; isotonic saline: mean difference = 8.94 [98.33% CI = 7.33/10.54]), individual symptoms and Endoscopy Score improved significantly (p < 0.001) in all treatment arms. Tolerability was assessed as "flawless" in more than 85% of all treatments, which is reflected in overall high rankings in the Nasal Spray Sensory Scale. Perception of nasal moisturisation was reported to be significantly higher in patients receiving hyaluronic acid plus dexpanthenol as compared to patients receiving hyaluronic acid or isotonic saline. No further significant differences were observed between the three treatments. CONCLUSION: All three tested sprays (hyaluronic acid, hyaluronic acid plus dexpanthenol and isotonic saline) proved to be suitable treatments for patients suffering from dry nose symptoms. (DRKS-ID: DRKS00013357).

Characterization of bromelain indicates a molar excess of inhibitor vs. enzyme molecules, a Jacalin-like lectin and Maillard reaction products.

The phytotherapeutic bromelain is a heterogeneous protein mixture, extracted from pineapple stem, with high proteolytic activity based on cysteine proteases. Its global protein chemical composition was analyzed qualitatively and quantitatively by SDS-PAGE and RP-HPLC. A SDS-PAGE method with elaborate sample pretreatment was developed, to cope with the bromelain's self-digestion properties and the hypothetical disulfide scrambling during electrophoresis. Both can produce misleading results, if not considered. RP-HPLC was applied for its high separation power for bromelain proteinaceous compounds. A peak identification and assignment to different protein classes in bromelain was done by enzyme kinetics and MS. The method was successfully applied for the quantitative determination of the molar ratio between inhibitor and enzyme and resulted to be approximately 3:2. Bromelain contains, from a molar point of view, inhibitor molecules as major component, which thus might be considered as a natural pharmaceutical excipient in Bromelain, because it protects the enzymes against autolysis. We described two methods to separate the inhibitor fraction from the enzyme fraction, RP-HPLC and size exclusion chromatography. A pineapple derived Jacalin-like-lectin, herein called 'Anlec', was identified and quantified by RP-HPLC-MS in bromelain and its content was determined to be 5%, related to all proteins in bromelain. Anlec binds specifically to mannose-containing glycans and is discussed in literature to possess anti-HIV medical potential. Bromelain could therefore be a possible and economic source for the production of Anlec. An isolation strategy of Anlec from bromelain, in high purity, is shown in this work. The presented RP-HPLC results are comprehensive in chemical information, and the method is expedient to provide appropriate bromelain protein isolations but also to accomplish quality control, covering all relevant protein components. It is furthermore shown, that proteins in bromelain may react with reducing sugars in a Maillard reaction to form glycated proteins. Maillard reaction products in bromelain are detected and characterized and could be responsible for the limited stability and storage times at room temperature of bromelain. Even the active center thiol group could be potentially glycated.

Novel coumarin- and quinolinone-based polycycles as cell division cycle 25-A and -C phosphatases inhibitors induce proliferation arrest and apoptosis in cancer cells.

Cell division cycle phosphatases CDC25 A, B and C are involved in modulating cell cycle processes and are found overexpressed in a large panel of cancer typology. Here, we describe the development of two novel quinone-polycycle series of CDC25A and C inhibitors on the one hand 1a-k, coumarin-based, and on the other 2a-g, quinolinone-based, which inhibit either enzymes up to a sub-micro molar level and at single-digit micro molar concentrations, respectively. When tested in six different cancer cell lines, compound 2c displayed the highest efficacy to arrest cell viability, showing in almost all cell lines sub-micro molar IC50 values, a profile even better than the reference compound NCS95397. To investigate the putative binding mode of the inhibitors and to develop quantitative structure-activity relationships, molecular docking and 3-D QSAR studies were also carried out. Four selected inhibitors, 1a, 1d, 2a and 2c have been also tested in A431 cancer cells; among them, compound 2c was the most potent one leading to cell proliferation arrest and decreased CDC25C protein levels together with its splicing variant. Compound 2c displayed increased phosphorylation levels of histone H3, induction of PARP and caspase 3 cleavage, highlighting its contribution to cell death through pro-apoptotic effects.

Heterologous expression of the plant cysteine protease bromelain and its inhibitor in Pichia pastoris.

Expression of proteases in heterologous hosts remains an ambitious challenge due to severe problems associated with digestion of host proteins. On the other hand, proteases are broadly used in industrial applications and resemble promising drug candidates. Bromelain is an herbal drug that is medicinally used for treatment of oedematous swellings and inflammatory conditions and consists in large part of proteolytic enzymes. Even though various experiments underline the requirement of active cysteine proteases for biological activity, so far no investigation succeeded to clearly clarify the pharmacological mode of action of bromelain. The potential role of proteases themselves and other molecules of this multi-component extract currently remain largely unknown or ill defined. Here, we set out to express several bromelain cysteine proteases as well as a bromelain inhibitor molecule in order to gain defined molecular entities for subsequent studies. After cloning the genes from its natural source Ananas comosus (pineapple plant) into Pichia pastoris and subsequent fermentation and purification, we obtained active protease and inhibitor molecules which were subsequently biochemically characterized. Employing purified bromelain fractions paves the way for further elucidation of pharmacological activities of this natural product. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:54-65, 2017.

Perioperative Bromelain Therapy after Wisdom Teeth Extraction - A Randomized, Placebo-Controlled, Double-Blinded, Three-Armed, Cross-Over Dose-Finding Study.

Reduction in postoperative edema and inflammatory reactions is the key to the posttraumatic regeneration process. Use of bromelain is well established in this indication, but there is some controversy with regard to the optimal dosing of this drug. The aim of our study was therefore to investigate the efficacy of dosage-dependent therapy with bromelain in patients after wisdom teeth extraction by comparing the registered dosage 1000 FIP (Fédération Internationale Pharmaceutique) against higher dosages of 3000 FIP and 4500 FIP. A total of 75 patients were randomized to one of the three dosage arms, and 68 of these patients were finally analyzed in the modified intention-to-treat population. Patients involved underwent two surgery sessions: one study period being conducted under treatment with bromelain and the other with placebo. Postoperative swelling determined by a 3D face scanning system was defined as the primary endpoint; further efficacy parameters were maximum swelling, pain, difficulty in swallowing, and use of analgesics. A superiority of treatment with 3000 FIP and 4500 FIP versus 1000 FIP could not be demonstrated. The analysis of pooled bromelain treatments versus placebo did, however, show a clear trend in favor of bromelain for all assessments. Adverse events did not occur more frequently under bromelain therapy compared with placebo. This study thus clearly supports the clinical relevance of treatment of postoperative conditions with bromelain, and the recommended daily dose was sufficiently effective in this trial and indication. Copyright © 2016 John Wiley & Sons, Ltd.

Chokeberry (Aronia melanocarpa (Michx.) Elliot) concentrate inhibits NF-κB and synergizes with selenium to inhibit the release of pro-inflammatory mediators in macrophages.

Black chokeberry has been known to play a protective role in human health due to its high polyphenolic content including anthocyanins and caffeic acid derivatives. In the present study, we first characterized the polyphenolic content of a commercial chokeberry concentrate and investigated its effect on LPS-induced NF-κB activation and release of pro-inflammatory mediators in macrophages in the presence or the absence of sodium selenite. Examination of the phytochemical profile of the juice concentrate revealed high content of polyphenols (3.3%), including anthocyanins, proanthocyanidins, phenolic acids, and flavonoids. Among them, cyanidin-3-O-galactoside and caffeoylquinic acids were identified as the major compounds. Data indicated that chokeberry concentrate inhibited both the release of TNFα, IL-6 and IL-8 in human peripheral monocytes and the activation of the NF-κB pathway in RAW 264.7 macrophage cells. Furthermore, chokeberry synergizes with sodium selenite to inhibit NF-κB activation, cytokine release and PGE2 synthesis. These findings suggest that selenium added to chokeberry juice enhances significantly its anti-inflammatory activity, thus revealing a sound approach in order to tune the use of traditional herbals by combining them with micronutrients.

Clinical efficacy of a spray containing hyaluronic Acid and dexpanthenol after surgery in the nasal cavity (septoplasty, simple ethmoid sinus surgery, and turbinate surgery).

Background. This prospective, controlled, parallel-group observational study investigated the efficacy of a spray containing hyaluronic acid and dexpanthenol to optimise regular treatment after nasal cavity surgery in 49 patients with chronic rhinosinusitis. Methods. The control group received standard therapy. Mucosal regeneration was determined using rhinoscopy sum score (RSS). Pre- and postoperative nasal patency was tested using anterior rhinomanometry. The participants were questioned about their symptoms. Results. Regarding all RSS parameters (dryness, dried nasal mucus, fibrin deposition, and obstruction), mucosal regeneration achieved good final results in both groups, tending to a better improvement through the spray application, without statistically significant differences during the whole assessment period, the mean values being 7.04, 5.00, 3.66, and 3.00 (intervention group) and 7.09, 5.14, 4.36, and 3.33 (control group). No statistically significant benefit was identified for nasal breathing, foreign body sensation, and average rhinomanometric volume flow, which improved by 12.31% (control group) and 11.24% (nasal spray group). Conclusion. The investigational product may have additional benefit on postoperative mucosal regeneration compared to standard cleaning procedures alone. However, no statistically significant advantage could be observed in this observational study. Double-blind, controlled studies with larger populations will be necessary to evaluate the efficacy of this treatment modality.

Placebo-controlled randomized clinical trial on the immunomodulating activities of low- and high-dose bromelain after oral administration - new evidence on the antiinflammatory mode of action of bromelain.

Bromelain has been used for treatment of inflammatory diseases for decades. However, the exact mechanism of action remains poorly understood. While in vitro investigations have shown conflicting effects on the release of various cytokines, no in vivo data were available. In this study, the effects on inflammation-related cytokines of two doses of bromelain were tested in a single dose placebo-controlled 3 × crossover randomized clinical trial. Cytokine circadian profiles were used to investigate the effects of bromelain on the human immune system by using stimulated whole-blood leukocytes. The effects seen in these cultures demonstrated a significant shift in the circadian profiles of the Th1 cell mediator interferon gamma (IFNγ; p < 0.043) after bromelain 3000 FIP (Fédération Internationale Pharmaceutique) units, and trends in those of the Th2-type cytokine IL-5 as well as the immunosuppressive cytokine interleukin (IL)-10. This suggests a general effect on the antigen-specific (T cell) compartment of the human immune system. This is the first time that bromelain has been shown to modulate the cellular responses of lymphocyte after oral use. It is postulated that the immunomodulating effect of bromelain observed in this trial is part of its known antiinflammatory activities. Further investigations will be necessary to verify the relevance of these findings to a diseased immune system.

Proanthocyanidins: oligomeric structures with unique biochemical properties and great therapeutic promise.

Proanthocyanidins represent a unique class of oligomeric and polymeric secondary metabolites found ubiquitously and in considerable amounts in plants and some algae. These substances exhibit a range of rather surprising physical and chemical properties which, once applied to living organisms, are translated into a multitude of biological activities. The latter include antioxidant properties, cancer chemoprevention, anti-inflammatory and anti-diabetic effects as well as some exceptional, yet highly interesting activities, such as anti-nutritional and antimicrobial activity. Despite the wide range of activities and possible medical/agricultural applications of proanthocyanidins, many questions still remain, including issues related to bioavailability, metabolism and the precise biochemical, extra- and intracellular targets and mode(s) of action of these highly potent materials. Among the various physical and chemical interactions of such substances, strong binding to proteins appears to form the basis of many of their biological activities. Once easy-to-use synthetic methods to produce appropriate quantities of pure proanthocyanidins are available, it will be possible to identify the prime biological targets of these oligomers, study oligomer-protein interactions in more detail and develop possible practical applications in medicine and agriculture.

Insights into the complex biosynthesis of the leupyrrins in Sorangium cellulosum So ce690.

The anti-fungal leupyrrins are secondary metabolites produced by several strains of the myxobacterium Sorangium cellulosum. These intriguing compounds incorporate an atypically substituted γ-butyrolactone ring, as well as pyrrole and oxazolinone functionalities, which are located within an unusual asymmetrical macrodiolide. Previous feeding studies revealed that this novel structure arises from the homologation of four distinct structural units, nonribosomally-derived peptide, polyketide, isoprenoid and a dicarboxylic acid, coupled with modification of the various building blocks. Here we have attempted to reconcile the biosynthetic pathway proposed on the basis of the feeding studies with the underlying enzymatic machinery in the S. cellulosum strain So ce690. Gene products can be assigned to many of the suggested steps, but inspection of the gene set provokes the reconsideration of several key transformations. We support our analysis by the reconstitution in vitro of the biosynthesis of the pyrrole carboxylic starter unit along with gene inactivation. In addition, this study reveals that a significant proportion of the genes for leupyrrin biosynthesis are located outside the core cluster, a 'split' organization which is increasingly characteristic of the myxobacteria. Finally, we report the generation of four novel deshydroxy leupyrrin analogues by genetic engineering of the pathway.

Glycerol lidocaine eardrops for the treatment of acute abacterial otitis externa.

Inflammations of the external auditory canal number among the most frequently occurring ear-nose-throat diseases. For local treatment, substances from various groups of active ingredients are used as combinations and as single-agent drugs, e.g. antibiotics, glucocorticoids or analgesics [1]. In the case of acute otitis externa, treatment measures focus on the reduction of pain and swelling. The study described here investigates the efficacy and safety of glycerol lidocaine eardrops for the treatment of acute abacterial otitis externa (CAS No. for glycerol: 56-81-5, lidocaine-HCl: 73-78-9). In this double-blind, three-arm study, 105 patients diagnosed with acute abacterial otitis externa were included and randomized to receive either glycerol eardrops, glycerol eardrops with 0.5% lidocaine, or glycerol eardrops with 2% lidocaine for seven days. The primary outcome parameter was the change of the five typical clinical symptoms, earache, itching, otorrhea, hearing impairment, and "clogged ear" at Visit 2 (Day 7) based on the initial examination on Day 0. Both therapy groups treated with a combination of glycerol and lidocaine exhibited definite improvement in overall symptoms after seven days. This improvement differed from the mild reduction of symptoms under treatment with glycerol eardrops alone. Overall improvement of symptoms, expressed by the area under the curve of the baseline-adjusted symptom sum score, yielded a mean value of 10.95 (standard deviation 27.4) for the morning survey of the groups receiving eardrops containing only glycerol; in comparison, for eardrops containing glycerol and 2% lidocaine it was 15.71 (+/- 23.6) and for glycerol with 0.5% lidocaine, 23.16 (+/- 19.4). No severe adverse events occurred. Five adverse events were documented during the clinical investigation, none of which was considered by the investigators to be related to the study medication. Local therapy with glycerol lidocaine eardrops is a safe, and cost-effective treatment for the widely spread clinical picture of acute abacterial otitis externa. The advantage regarding efficacy of this combination compared with glycerol eardrops must be demonstrated in an adequately powered clinical trial.

DKxanthene biosynthesis--understanding the basis for diversity-oriented synthesis in myxobacterial secondary metabolism.

The DKxanthenes are a family of yellow pigments which play a critical role in myxobacterial development. Thirteen unique structures from Myxococcus xanthus DK1622 differ in the length of their characteristic polyene functionality, as well as the extent of methyl branching. We aimed to understand the mechanistic basis for this "molecular promiscuity" by analyzing the gene cluster in DK1622, and comparing it to the DKxanthene biosynthetic locus in a second myxobacterium, Stigmatella aurantiaca DW4/3-1, which produces a more limited range of compounds. While the core biosynthetic machinery is highly conserved, M. xanthus contains a putative asparagine hydroxylase function which is not present in S. aurantiaca. This observation accounts, in part, for the significantly larger metabolite family in M. xanthus. Detailed analysis of the encoded hybrid polyketide synthase (PKS)-nonribosomal peptide synthetase (NRPS) assembly line provides direct evidence for the mechanism underlying the variable polyene length and the observed pattern of methyl functionalities.

Mutasynthesis-derived myxalamids and origin of the isobutyryl-CoA starter unit of myxalamid B.

Myxalamids are potent inhibitors of the eukaryotic electron transport chain produced by different myxobacteria. Here, we describe the identification of the myxalamid biosynthesis gene cluster from Myxococcus xanthus. Additionally, new myxalamids (5-13) have been obtained by mutasynthesis from bkd mutants of M. xanthus and Stigmatella aurantiaca. Moreover, as these bkd mutants are still able to produce myxalamid B (2), the origin of the isobutyryl-CoA (IB-CoA) starter unit required for its biosynthesis has been determined. In a M. xanthus bkd mutant, IB-CoA originates from valine, but in S. aurantiaca this starter unit is derived from alpha-oxidation of iso-odd fatty acids, thereby connecting primary and secondary metabolism.

The unique DKxanthene secondary metabolite family from the myxobacterium Myxococcus xanthus is required for developmental sporulation.

Under starvation conditions myxobacteria form multicellular fruiting bodies in which vegetative cells differentiate into heat- and desiccation-resistant myxospores. Myxobacteria in general are a rich source of secondary metabolites that often exhibit biological activities rarely found in nature. Although the involvement of a yellow compound in sporulation and fruiting body formation of Myxococcus xanthus was described almost 30 years ago, the chemical principle of the pigment remained elusive. This work presents the isolation and structure elucidation of a unique class of pigments that were named DKxanthenes (DKX). The corresponding biosynthetic gene cluster was identified, and DKX-negative mutants were constructed to investigate the physiological role of DKX during development. In these mutants, fruiting body formation was delayed. Moreover, severely reduced amounts of viable spores were observed after 120 h of starvation, whereas no viable spores were formed at all after 72 h. The addition of purified DKX to the mutants resulted in the formation of viable spores after 72 h. Even though an antioxidative activity could be assigned to DKX, the true biochemical mechanism underlying the complementation remains to be elucidated.