In silico exploration of deep-sea fungal metabolites as inhibitor of Ebola and Marburg VP35 and VP40.

VP30 and VP40 proteins of Ebola and Marburg viruses have been recognized as potential targets for antiviral drug development due to their essential roles in the viral lifecycle. Targeting these proteins could disrupt key stages of the viral replication process, inhibiting the viruses' ability to propagate and cause disease. The current study aims to perform molecular docking and virtual screening on deep-sea fungal metabolites targeting Marburg virus VP40 Dimer, matrix protein VP40 from Ebola virus Sudan, Ebola VP35 Interferon Inhibitory Domain, and VP35 from Marburg virus. The top ten compounds for each protein target were chosen using the glide score. All the compounds obtained indicate a positive binding interaction. Furthermore, AdmetSAR was utilized to investigate the pharmacokinetics of the inhibitors chosen. Gliotoxin was used as a ligand with Marburg virus VP40 Dimer, Austinol with matrix protein VP40 from Ebola virus Sudan, Ozazino-cyclo-(2,3-dihydroxyl-trp-tyr) with Ebola VP35 Interferon Inhibitory Domain, and Dehydroaustinol with VP35 from Marburg virus. MD modeling and MMPBSA studies were used to provide a better understanding of binding behaviors. Pre-clinical experiments can assist validate our in-silico studies and assess whether the molecule can be employed as an anti-viral drug.

Outlining the Phytoconstituents of Greek Clover Herb Extract and Assessment of Its Effect against Foodborne Infections Caused by Salmonella typhimurium.

Owing to the spread of resistance between pathogenic bacteria, searching for novel compounds with antibacterial activity is essential. Here, we investigated the potential antibacterial activity of Greek clover or Trigonella foenum-graecum herb extract on Salmonella typhimurium clinical isolates. The chemical profile of the herb was initially determined using LC-ESI-MS/MS, which explored 36 different compounds. Interestingly, the fenugreek extract possessed antibacterial action in vitro with minimum inhibitory concentrations of 64 to 512 µg/mL. The potential mechanism of action was studied by elucidating the effect of the fenugreek extract on the membrane properties of S. typhimurium bacteria, including the inner and outer membrane permeability and membrane integrity. Remarkably, the fenugreek extract had detrimental effects on the membrane properties in 40-60% of the isolates. Moreover, the in vivo antibacterial action was studied using a gastrointestinal infection model with S. typhimurium bacteria. Interestingly, the fenugreek extract (200 mg/kg) improved the infection outcomes in the tested mice. This was represented by the noteworthy decrease (p < 0.05) in the bacterial count in the small intestine and caecum tissues. The survival rate of the fenugreek-extract-treated mice significantly increased compared to the S. typhimurium-infected group. Additionally, there was an improvement in the histological and immunohistochemical features of tumor necrosis factor-alpha. In addition, using an ELISA and qRT-PCR, there was an improvement in the proinflammatory and oxidative stress markers in the fenugreek-extract-treated group. Consequently, fenugreek extract should be investigated further on other food pathogens.

Rosuvastatin and diosmetin inhibited the HSP70/TLR4 /NF-κB p65/NLRP3 signaling pathways and switched macrophage to M2 phenotype in a rat model of acute kidney injury induced by cisplatin.

Numerous efforts to manage acute kidney injury (AKI) were unsuccessful because its pathophysiology is still poorly understood. Thus, our research hotspot was to explore the possible renoprotective effects of rosuvastatin (Ros) and diosmetin (D) on macrophage polarization and the role of HSP70/TLR4/MyD88/NF-κB p65/NLRP3/STAT3 signaling in cis-induced AKI and study the activity of D against uropathogenic bacteria. Fifty-four albino male rats were randomized into 9 groups equally: Control, Ros, D20, D40, untreated Cis, and Cis groups cotreated with Ros, D20, D40 and Ros+D40 for 10 days. Our results indicated that Ros and D, in a dose-dependent manner, markedly restored body weight, systolic blood pressure, and renal histological architecture besides significantly upregulated SOD levels, expression of anti-inflammatory CD163 macrophages, arginase1levels, IL-10 levels,STAT3 and PCNA immunoreactivity. Also, they significantly downregulated renal index, serum urea, serum creatinine, serum cystatin c, inflammatory biomarkers (C reactive protein, IL1ß & TNF-α), MDA levels, HSP70/TLR4/MyD88/NF-κB p65/NLRP3 expressions, proinflammatory CD68 macrophages and caspase-3 immunoreactivity, resulting in a reversal of cis-induced renal damage. These findings were further confirmed by molecular docking that showed the binding affinity of Ros and D towards TLR4 and NLRP3. Furthermore, D had antibacterial action with a minimum inhibitory concentration ranging from 128 to 256 µg/mL and caused a delay in the growth of the tested isolates, and negatively affected the membrane integrity. In conclusion, Ros and D had antioxidant, anti-inflammatory and antiapoptotic properties and switched macrophage from proinflammatory CD68 to anti-inflammatory CD163. Additionally, the targeting of HSP70/TLR4/MyD88/NF-κB p65/NLRP3/STAT3 signals are effective therapeutic strategy in AKI.

Molecular docking and ADMET studies of halogenated metabolites from marine sponges as inhibitors of wild-type and mutants PBP2 in Neisseria gonorrhoeae.

Gonorrhoea is a sexually transmitted infection (STI) caused by the bacteria Neisseria gonorrhoeae. Gonorrhoea symptoms can vary, although roughly 50% of women and 10% of men infected with N. gonorrhoeae may be asymptomatic. If left untreated, gonorrhoea can cause major health problems. However, no effective treatment or vaccination is currently available. The enzyme penicillin-binding protein 2 (PBP2) is necessary for cell wall synthesis during N. gonorrhoeae cell growth. The goal of this study is to investigate the molecular interactions of three PBP2 variants with halogenated marine sponge metabolites using molecular docking, molecular dynamic simulation, and ADMET analysis. The docking findings were evaluated using the glide gscore, and the top 20 compounds docked against each PBP2 protein receptor were chosen. Furthermore, the selected compounds underwent ADMET analysis, indicating that they have the potential for therapeutic development. Among the selected compounds, Bromoageliferin had the highest affinity for PBP2, Psammaplysin E for the penicillin-resistant variation of PBP2 protein, and Preaxinellamine for the cephalosporin-resistant variant of PBP2 protein. Additionally, MM-GBSA binding free energy and molecular dynamics simulations were used to support the docking investigations. The results of the study suggest that these compounds may eventually be used to treat gonorrhoea. However, computer validations were included in this study, and more in-vitro research is required to turn these prospective inhibitors into clinical drugs.Communicated by Ramaswamy H. Sarma.

Deep-sea fungal metabolites as potential inhibitors of glucose-regulatory enzymes: In silico structure-activity analysis.

Chronic diabetes mellites related hyperglycemia is a major cause of mortality and morbidity due to further complications like retinopathy, hypertension and cardiovascular diseases. Though several synthetic anti-diabetes drugs specifically targeting glucose-metabolism enzymes are available, they have their own limitations, including adverse side-effects. Unlike other natural or marine-derived pharmacologically important molecules, deep-sea fungi metabolites still remain under-explored for their anti-diabetes potential. We performed structure-based virtual screening of deep-sea fungal compounds selected by their physiochemical properties, targeting crucial enzymes viz., α -amylase, α -glucosidase, pancreatic-lipoprotein lipase, hexokinase-II and protein tyrosine phosphatase-1B involved in glucose-metabolism pathway. Following molecular docking scores and MD simulation analyses, the selected top ten compounds for each enzyme, were subjected to pharmacokinetics prediction based on their AdmetSAR- and pharmacophore-based features. Of these, cladosporol C, tenellone F, ozazino-cyclo-(2,3-dihydroxyl-trp-tyr), penicillactam and circumdatin G were identified as potential inhibitors of α -amylase, α -glucosidase, pancreatic-lipoprotein lipase, hexokinase-II and protein tyrosine phosphatase-1B, respectively. Our in silico data therefore, warrants further experimental and pharmacological studies to validate their anti-diabetes therapeutic potential.

Administration of α-lipoic acid and silymarin attenuates aggression by modulating endocrine, oxidative stress and inflammatory pathways in mice.

Aggression, a highly prevalent behavior among all the psychological disorders having strong association with psychiatric imbalance, neuroendocrine changes and neurological disturbances (including oxidative stress & neuroinflammation) require both pharmacological and non-pharmacological treatments. Focusing the preclinical neuroendocrine determinants of aggression, this interventional study was designed to elucidate the curative effect of antioxidants on aggression in male mice. Adult albino male mice (n = 140) randomly divided into two main treatment groups for α-lipoic acid (ALA) and silymarin with 5 subgroups (n = 10) for each curative study, namely control, disease (aggression-induced), standard (diazepam, 2.5 mg/kg), low dose (100 mg/kg) and high dose (200 mg/kg) treatment groups of selected antioxidants. Resident-intruder paradigm and levodopa (L-dopa 375 mg/kg, p.o.) induced models were used for aggression. Effect of antioxidant treatment (i.e., 21 days bid) on aggression was assessed by evaluating the changes in aggressive behavior, oxidative stress biomarkers superoxide dismutase, catalase, glutathione, nitrite and malondialdehyde (SOD, CAT, GSH, nitrite & MDA), neurotransmitters (dopamine, nor-adrenaline and serotonin), pro-inflammatory cytokines tumor necrosis factor-α and interleukin- 6 (TNF-α & IL-6) along with serum testosterone examination. This study showed potential ameliorative effect on aggressive behavior with both low (100 mg/kg) and high (200 mg/kg) doses of antioxidants (ALA & silymarin). Resident-intruder or L-dopa induced aggression in male mice was more significantly tuned with ALA treatment than silymarin via down regulating both oxidative stress and inflammatory biomarkers. ALA also exhibited notable effects in managing aggression-induced disturbances on plasma testosterone levels. In conclusion, ALA is more effective than silymarin in attenuating aggression in mice.

Fenofibrate and Diosmetin in a rat model of testicular toxicity: New insight on their protective mechanism through PPAR-α/NRF-2/HO-1 signaling pathway.

One of the most significant chemotherapeutic side effects of cisplatin (Cis) that limits its use and efficacy is testicular toxicity. Thus, the objective of the present study was to investigate the possible ameliorative effect of Fenofibrate (Fen), Diosmetin (D), and their combination against cis-mediated testicular damage. Fifty-four adult male albino rats were randomly allocated into nine groups (6 rats each): Control group, Fen (100 mg/kg), D20 (20 mg/kg), D40 (40 mg/kg), Cis group (7 mg/kg), Cis +Fen group (7 mg/kg+100 mg/kg), Cis+D20 group (7 mg/kg+20 mg/kg), Cis+D40 group (7 mg/kg+40 mg/kg), Cis+Fen+D40 treated group (7 mg/kg+100 mg/kg+40 mg/kg). Relative testicular weight, epididymal sperm count and viability, serum testosterone level, testicular oxidative stress indices, mRNA expression of peroxisome proliferator-activated receptor alpha (PPAR-α), nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1), histopathological, and immunohistochemical alterations were assessed. Our results revealed that cis administration induced testicular oxidative and inflammatory damage as indicated by a substantial reduction in relative testicular weight, sperm parameters, serum testosterone levels, the antioxidant enzyme activity of catalase, and Johnson's histopathological score, PPAR-α/NRF-2/HO-1 and proliferating cell nuclear antigen (PCNA) immunoexpression with marked increment in malondialdehyde (MDA), Cosentino's score, nuclear factor kappa B (NF-κß p65), interleukin (IL)- 1ß and caspase 3 in testicular tissue. Interestingly, Fen and D diminished the harmful effects of cis on testes via upregulation of the antioxidant activities and downregulation of lipid peroxidation, apoptosis, and inflammation. Moreover, the combination therapy Fen/D40 also exhibited a more pronounced enhancement of previous markers than either treatment alone. In conclusion, because of their antioxidant, anti-inflammatory, and anti-apoptotic properties, cotreatment with Fen or D or their combination could be beneficial in reducing the harmful impacts of cis on testicular tissue, particularly in patients that receive cis chemotherapy.

Silver Nanoparticles Prepared Using Encephalartos laurentianus De Wild Leaf Extract Have Inhibitory Activity against Candida albicans Clinical Isolates.

Candida albicans is a major human opportunistic pathogen causing infections, which range from cutaneous to invasive systemic infections. Herein, the antifungal and anti-biofilm potential of silver nanoparticles (AgNPs) green synthesized in the presence of Encephalartos laurentianus leaf extract (ELLE) were investigated. The bioactive chemicals of ELLE, including phenolics, flavonoids, and glycosides were identified and quantified for the first time. AgNPs showed minimum inhibitory concentration (MIC) values against C. albicans clinical isolates ranging from 8 to 256 µg/mL. In addition, AgNPs significantly decreased biofilm formation. The impact of AgNPs on the expression of the genes encoding biofilm formation was assessed using qRT-PCR. AgNPs had a beneficial role in the macroscopic wound healing, and they resulted in complete epithelization without any granulation tissue or inflammation. Treatment with AgNPs resulted in negative immunostaining of tumor necrosis factor-α. The levels of the inflammation markers, interleukin-6 and interleukin-1ß, significantly decreased (p < 0.05) in the AgNPs-treated group. There was also a pronounced increase in the gene expression of fibronectin and platelet-derived growth factor in the wound tissues. Thus, AgNPs synthesized using ELLE may be a promising antifungal and wound healing agent.

Metabolic Profiling of Jasminum grandiflorum L. Flowers and Protective Role against Cisplatin-Induced Nephrotoxicity: Network Pharmacology and In Vivo Validation.

Cisplatin (CP) is a powerful chemotherapeutic agent; however, its therapeutic use is restricted due to its nephrotoxicity. In this work, we profiled the phytoconstituents of Jasminum grandiflorum flower extract (JGF) using LC-MS/MS and explored the possible molecular mechanisms against acute renal failure through pharmacological network analysis. Furthermore, the possible molecular mechanisms of JGF against acute renal failure were verified in an in vivo nephrotoxicity model caused by cisplatin. LC-MS analysis furnished 26 secondary metabolites. Altogether, there were 112 total hit targets for the identified metabolites, among which 55 were potential consensus targets related to nephrotoxicity based on the network pharmacology approach. Upon narrowing the scope to acute renal failure, using the DisGeNET database, only 30 potential targets were determined. The computational pathway analysis illustrated that JGF might inhibit renal failure through PI3K-Akt, MAPK signaling pathway, and EGFR tyrosine kinase inhibitor resistance. This study was confirmed by in vivo experiment in which kidneys were collected for histopathology and gene expression of mitogen-activated protein kinase 4 (MKK4), MKK7, I-CAM 1, IL-6, and TNF receptor-associated factor 2 (TRAF2). The animal-administered cisplatin exhibited a substantial rise in the expression levels of the MMK4, MKK7, I CAM 1, and TRFA2 genes compared to the control group. To summarize, J. grandiflorum could be a potential source for new reno-protective agents. Further experiments are needed to confirm the obtained activities and determine the therapeutic dose and time.

Bilosomes as Nanoplatform for Oral Delivery and Modulated In Vivo Antimicrobial Activity of Lycopene.

Owing to the disseminating resistance among pathogenic bacteria, especially Klebsiella pneumoniae, there is a high need for alternate compounds with antibacterial activity. Herein, lycopene was isolated from Lycopersicon esculentum L. Molecular docking approach was employed to explore lycopene binding affinity to selected vital proteins of K. pneumoniae with the binding mechanisms being investigated. This proposed a promising antibacterial activity of lycopene. However, the pharmacological use of lycopene is hampered by its poor solubility and limited oral bioavailability. Accordingly, bilosomes were fabricated for oral lycopene delivery. The computed entrapment efficiency, mean vesicular size, and zeta potential values for the optimized formulation were 93.2 ± 0.6%, 485.8 ± 35.3 nm, and -38.3 ± 4, respectively. In vitro drug release studies revealed controlled lycopene release from constructed bilosomes, with the drug liberation being based on the Higuchi kinetics model. Transmission electron microscopic evaluation of bilosomes revealed spherical nanovesicles free from aggregates. Moreover, the in vitro and in vivo antibacterial activity of lycopene and its constructed formulations against multidrug-resistant K. pneumoniae isolates were explored. The optimized bilosomes exhibited the lowest minimum inhibitory concentrations ranging from 8 to 32 µg/mL. In addition, scanning electron microscopy revealed remarkable deformation and lysis of the bilosomes-treated bacterial cells. Regarding in vivo investigation, a lung infection model in mice was employed. The tested bilosomes reduced the inflammation and congestion in the treated mice's lung tissues, resulting in normal-sized bronchioles and alveoli with very few congested vessels. In addition, it resulted in a significant reduction in pulmonary fibrosis. In conclusion, this study investigated the potential activity of the naturally isolated lycopene in controlling infections triggered by multidrug-resistant K. pneumoniae isolates. Furthermore, it introduced bilosomes as a promising biocompatible nanocarrier for modulation of oral lycopene delivery and in vivo antimicrobial activity.

Anti-Biofilm and Antibacterial Activities of Cycas media R. Br Secondary Metabolites: In Silico, In Vitro, and In Vivo Approaches.

Enterococcus species possess many virulence factors that have an essential role in exacerbating the infections caused by them. The current study aimed to evaluate the effect of the secondary metabolites ginkgetin (GINK) and sotetsuflavone (SOTE), isolated from Cycas media R. Br dichloromethane fraction, on Enterococcus faecalis (E. faecalis) isolates for the first time. The antibacterial and antivirulence activities of the isolated compounds were investigated using docking studies and in vitro by determination of the minimum inhibitory concentrations (MICs). Additionally, flow cytometry and scanning electron microscope (SEM) were utilized to assess the effect of SOTE on the tested bacteria. Moreover, crystal violet assay and qRT-PCR were used to test the effect of SOTE on the biofilm-forming ability of E. faecalis isolates. In addition, a systemic infection model was utilized in vivo to investigate the antibacterial activity of SOTE. We found that both GINK and SOTE showed a good affinity for the five proteins enrolled in the virulence of E. faecalis, with SOTE being the highest, suggesting the possible mechanisms for the antivirulence activity of both ligands. In addition, SOTE exhibited a higher antibacterial activity than GINK, as the values of the MICs of SOTE were lower than those of GINK. Thus, we performed the in vitro and in vivo assays on SOTE. However, they did not exhibit any significant variations (p > 0.05) in the membrane depolarization of E. faecalis isolates. Moreover, as evaluated by SEM, SOTE caused distortion and deformation in the treated cells. Regarding its impact on the biofilm formation, it inhibited the biofilm-forming ability of the tested isolates, as determined by crystal violet assay and qRT-PCR. The in vivo experiment revealed that SOTE resulted in a reduction of the inflammation of the liver and spleen with an increase in the survival rate. SOTE also improved the liver-function tests and decreased tumor necrosis factor-alpha using immunostaining and the inflammation markers, interleukins (IL-1ß and IL-6), using ELISA. Thus, we can conclude that SOTE could be a promising compound that should be investigated in future preclinical and clinical studies.

Promising Antifungal Activity of Encephalartos laurentianus de Wild against Candida albicans Clinical Isolates: In Vitro and In Vivo Effects on Renal Cortex of Adult Albino Rats.

Candida albicans can cause various infections, especially in immunocompromised patients. Its ability to develop resistance to the current antifungal drugs as well as its multiple virulence factors have rendered the problem even more complicated. Thus, in the present investigation, we elucidated an in vitro and in vivo antifungal activity of Encephalartos laurentianus methanol extract (ELME) against C. albicans clinical isolates for the first time. A phytochemical identification of 64 compounds was conducted in ELME using LC-MS/MS. Interestingly, ELME exhibited antifungal activity with MIC values that ranged from 32-256 µg/mL. Furthermore, we investigated the antibiofilm activity of ELME against the biofilms formed by C. albicans isolates. ELME displayed antibiofilm activity using a crystal violet assay as it decreased the percentages of cells, moderately and strongly forming biofilms from 62.5% to 25%. Moreover, the antibiofilm impact of ELME was elucidated using SEM and fluorescent microscope. A significant reduction in the biofilm formation by C. albicans isolates was observed. In addition, we observed that ELME resulted in the downregulation of the biofilm-related tested genes (ALS1, BCR1, PLB2, and SAP5) in 37.5% of the isolates using qRT-PCR. Besides, the in vivo antifungal activity of ELME on the kidney tissues of rats infected with C. albicans was investigated using histological and immunohistochemical studies. ELME was found to protect against C. albicans induced renal damage, decrease desmin and inducible nitric oxide synthase, increase alkaline phosphatase, and increase infected rats' survival rate. Additionally, the cytotoxicity of ELME was elucidated on Human Skin Fibroblast normal cells using MTT assay. ELME had an IC50 of 31.26 µg/mL. Thus, we can conclude that ELME might be a promising future source for antifungal compounds.

Encephalartos villosus Lem. Displays a Strong In Vivo and In Vitro Antifungal Potential against Candida glabrata Clinical Isolates.

Recently, Candida glabrata has been recognized as one of the most common fungal species that is highly associated with invasive candidiasis. Its spread could be attributed to its increasing resistance to antifungal drugs. Thus, there is a high need for safer and more efficient therapeutic alternatives such as plant extracts. Here, we investigated the antifungal potential of Encephalartos villosus leaves methanol extract (EVME) against C. glabrata clinical isolates. Tentative phytochemical identification of 51 metabolites was conducted in EVME using LC-MS/MS. EVME demonstrated antifungal activity with minimum inhibitory concentrations that ranged from 32 to 256 µg/mL. The mechanism of the antifungal action was studied by investigating the impact of EVME on nucleotide leakage. Additionally, a sorbitol bioassay was performed, and we found that EVME affected the fungal cell wall. In addition, the effect of EVME was elucidated on the efflux activity of C. glabrata isolates using acridine orange assay and quantitative real-time PCR. EVME resulted in downregulation of the expression of the efflux pump genes CDR1, CDR2, and ERG11 in the tested isolates with percentages of 33.33%, 41.67%, and 33.33%, respectively. Moreover, we investigated the in vivo antifungal activity of EVME using a murine model with systemic infection. The fungal burden was determined in the kidney tissues. Histological and immunohistochemical studies were carried out to investigate the effect of EVME. We noticed that EVME reduced the congestion of the glomeruli and tubules of the kidney tissues of the rats infected with C. glabrata. Furthermore, it decreased both the proinflammatory cytokine tumor necrosis factor-alpha and the abnormal collagen fibers. Our results reveal, for the first time, the potential in vitro (by inhibition of the efflux activity) and in vivo (by decreasing the congestion and inflammation of the kidney tissues) antifungal activity of EVME against C. glabrata isolates.

The Mechanistic Perspective of Bilobetin Protective Effects against Cisplatin-Induced Testicular Toxicity: Role of Nrf-2/Keap-1 Signaling, Inflammation, and Apoptosis.

Cisplatin (CP) is a productive anti-tumor used to treat numerous tumors. However, multiple toxicities discourage prolonged use, especially toxicity on the reproductive system. This experiment was mapped out to determine the potential therapeutic impact of Bilobetin on CP-induced testicular damage. Herein, Bilobetin was isolated from Cycas thouarsii leaves R. Br ethyl acetate fractions for the first time. A single dose of CP (7 mg/kg, IP) was used to evoke testicular toxicity on the third day. Rats were classified into five groups; Normal control, Bilobetin 12 mg/kg, Untreated CP, and CP treated with Bilobetin (6 and 12 mg/kg, respectively) orally daily for ten days. Bilobetin treatment ameliorated testicular injury. In addition, it boosted serum testosterone levels considerably and restored relative testicular weight. Nevertheless, apoptosis biomarkers such as P53, Cytochrome-C, and caspase-3 decreased significantly. Additionally, it enhanced the testes' antioxidant status via the activation of Nrf-2, inhibition of Keap-1, and significant elevation of SOD activity in addition to a reduction in lipid peroxidation. Histopathologically, Bilobetin preserved testicular architecture and improved testicular immunostaining of Ki67 substantially, showing evidence of testicular regeneration. Bilobetin's beneficial effects on CP-induced testicular damage are associated with enhanced antioxidant effects, lowered apoptotic signals, and the restoration of testes' regenerative capability. In addition, Bilobetin may be used in combination with CP in treatment protocols to mitigate CP-induced testicular injury.

One-step, stereoselective synthesis of octahydrochromanes via the Prins reaction and their cannabinoid activities.

Novel, functionalized octahydrochromene derivatives were synthesized in a single step via the Prins reaction. Enantiomerically pure (+)-isopulegol was reacted with benzaldehyde to stereoselectively yield the corresponding octahydro-2H-chromen-4-ol derivative containing five stereocenters. A total of 10 compounds were synthesized by altering the enantiomer of isopulegol and the substituted benzaldehyde, and the resulting enantiopure octahydrochromenes were screened in vitro against the cannabinoid receptor isoforms CB1 and CB2. Compounds containing an olefin at the C4 position [(+)-3c, (-)-3c, (-)-7c, (-)-9c and (-)-11c] of the octahydrochromene scaffold were found to exhibit reasonable displacement of [3H] CP55,940 from the CB receptors, whereas the corresponding hydroxy analogs [(+)-3a, (+)-3b, (-)-3a, (-)-3b and (+)-5a] had very little or no effect.