Sclareol Research Articles

Sclareol protected against intestinal barrier dysfunction ameliorating Crohn's disease-like colitis via Nrf2/NF-B/MLCK signalling

BackgroundInflammation-induced intestinal barrier dysfunction is not only a pathological feature of Crohn's disease (CD) but also an important therapeutic target. Sclareol (SCL) is a nontoxic natural plant compound with anti-inflammatory effect, but its role in CD has not been established. MethodsIn vivo studies of mice with TNBS-induced colitis were carried out to evaluate the effects of SCL on CD-like colitis and intestinal barrier function. In vitro, a TNF-α-induced colonic organoid model was established to test the direct effect of SCL on inflammation-induced intestinal barrier injure and inflammatory response. The Nrf2/NF-κB/MLCK signalling was analysed to explore the mechanism of SCL. ResultsIn vivo, SCL largely alleviated the colitis in TNBS mice, as evidenced by improvements in the weight loss, colitis symptoms, endoscopic score, macroscopic histological score, and histological inflammation score. Moreover, SCL significantly improved intestinal barrier dysfunction, manifested as reduced intestinal permeability and decreased intestinal bacterial translocation in TNBS mice. Importantly, SCL antagonised the intestinal mucosal inflammation while protecting tight junctions in TNBS mice. In vitro, SCL largely depressed pro-inflammatory cytokines levels and improved intestinal epithelial permeability in a TNF-α-induced colonic organoid model. In the context of CD, the protective effects of SCL against inflammation and intestinal barrier damage are at least partially results from the Nrf2 signalling activation and the NF-κB/MLCK signalling inhibition. ConclusionsSCL improved intestinal barrier dysfunction and alleviated CD-like colitis, possibly through modulation of Nrf2/NF-κB/MLCK signalling. In view of SCL's safety profile, there is hope that it will be useful in the clinic.

Novel hybrid compounds of sclareol and doxorubicin as potential anticancer nanotherapy for glioblastoma

Two novel hybrid compounds, CON1 and CON2, have been developed by combining sclareol (SC) and doxorubicin (DOX) into a single molecular entity. These hybrid compounds have a 1:1 molar ratio of covalently linked SC and DOX. They have demonstrated promising anticancer properties, especially in glioblastoma cells, and have also shown potential in treating multidrug-resistant (MDR) cancer cells that express the P-glycoprotein (P-gp) membrane transporter. CON1 and CON2 form nanoparticles, as confirmed by Zetasizer, transmission electron microscopy (TEM), and chemical modeling. TEM also showed that CON1 and CON2 can be found in glioblastoma cells, specifically in the cytoplasm, different organelles, nucleus, and nucleolus. To examine the anticancer properties, the U87 glioblastoma cell line, and its corresponding multidrug-resistant U87-TxR cell line, as well as patient-derived astrocytoma grade 3 cells (ASC), were used, while normal human lung fibroblasts were used to determine the selectivity. CON1 and CON2 exhibited better resistance and selectivity profiles than DOX, showing less cytotoxicity, as evidenced by real-time cell analysis, DNA damage determination, cell death induction, mitochondrial respiration, and mitochondrial membrane depolarization studies. Cell cycle analysis and the β-galactosidase activity assay suggested that glioblastoma cells die by senescence following CON1 treatment. Overall, CON1 and CON2 showed great potential as they have better anticancer features than DOX. They are promising candidates for additional preclinical and clinical studies on glioblastoma.

Quercetin increases the antidepressant-like effects of sclareol and antagonizes diazepam in thiopental sodium-induced sleeping mice: A possible GABAergic transmission intervention.

Quercetin is the most common polyphenolic flavonoid present in fruits and vegetables demonstrating versatile health-promoting effects. This study aimed to examine the effects of quercetin (QR) and sclareol (SCL) on the thiopental sodium (TS)-induced sleeping and forced swimming test (FST) mouse models. SCL (1, 5, and 10 mg/kg, p.o.) or QR (50 mg/kg, p.o.) and/or diazepam (DZP) (3 mg/kg, i.p.) were employed. After 30 min of TS induction, individual or combined effects on the animals were checked. In the FST test, the animals were subjected to forced swimming after 30 min of administration of the test and/or controls for 5 min. In this case, immobility time was measured. In silico studies were conducted to evaluate the involvement of GABA receptors. SCL (5 and 10 mg/kg) significantly increased the latency and decreased sleeping time compared to the control in the TS-induced sleeping time study. DZP (3 mg/kg) showed a sedative-like effect in animals in both sleeping and FST studies. QR (50 mg/kg) exhibited a similar pattern of activity as SCL. However, its effects were more prominent than those of SCL groups. SCL (10 mg/kg) altered the DZP-3-mediated effects. SCL-10 co-treated with QR-50 significantly (p < 0.05) increased the latency and decreased sleep time and immobility time, suggesting possible synergistic antidepressant-like effects. In silico studies revealed that SCL and QR demonstrated better binding affinities with GABAA receptor, especially α2, α3, and α5 subunits. Both compounds also exhibited good ADMET and drug-like properties. In animal studies, the both compounds worked synergistically to provide antidepressant-like effects in a slightly different fashion. As a conclusion, the combined administration of SCL and QR may be used in upcoming neurological clinical trials, according to in vivo and in silico findings. However, additional investigation is necessary to verify this behavior and clarify the potential mechanism of action.

Characterization of Spent Yeast Streams from Precision Fermentations Driven by Genetically Engineered Yeasts: Valorization Potential for a Circular Bioeconomy

Currently, valuable biomolecules are sustainably produced through fermentation using genetically modified microorganisms. However, this industry also generates several waste streams, such as spent yeast (SY). To close the sustainability loop in bioproduction, it is essential to define valorization strategies for such waste streams. Hence, this study aimed to investigate the compositional differences among these novel SYs, intending to pave the way for devising highly effective and beneficial valorization strategies for these streams. In this work, SYs derived from the production of beer (SBY) and six biomolecules [β-farnesene (Fene), rebaudioside M (Reb M), manool (MN), patchouli (PAT), sandalwood (SDW), and sclareol (SCL)] through fermentations driven by engineered yeasts were characterized. The results showed that SY from Fene, MN, and PAT production have similar concentrations of protein (35.9–44% dw), minerals, and amino acids, being compatible with bulking and use as nitrogen sources. Those derived from Reb M production showed significantly higher levels of lipids (21 ± 2.6% dw) compared to all the other SYs (1.7–10.8% dw), whereas the ones derived from SCL production showed significantly higher levels of inorganic matter (45%) compared with those found in the other SYs (1.2–11.3% dw). The results showed that assessing the extent of compositional variation among different SYs derived from precision fermentations represents a primary step toward developing efficient valorization or biorefining strategies.Graphical

Sclareol exerts an anti-inflammatory effect, possibly through COXs inhibition pathway: In vivo and in silico studies

Chronic and severe inflammation results in many diseases and disorders in humans. Currently, available conventional anti-inflammatory drugs have numerous mild-to-severe side effects. Thus, there is a need for safe, effective, affordable, and alternative anti-inflammatory drugs. This study aimed to evaluate the anti-inflammatory effect of sclareol (SCL), a diterpene alcohol that is the principal ingredient in the refined oil of Salvia sclarea (L.), through in vivo and in silico studies. First, we examined the individual and combined effects of SCL (5, 10, and 20 mg/kg) and standard drugs celecoxib (CXB) or ketoprofen (KPN) at 42 mg/kg (p.o.) on the formalin-induced inflammatory Swiss mice. Additionally, an in silico analysis was conducted to evaluate the potential anti-inflammatory mechanism of this study. For this, we examined the potentiality of SCL and standards to interact with cyclooxygenase (COX) -1 and COX-2 receptors. Our findings suggest that SCL exhibits a dose-dependent anti-inflammatory effect in mice. SCL-20 mg/kg significantly reduced the number of paw licks and paw edema diameters. Moreover, SCL-20 combined with CXB-42 and KPN-42 demonstrated better anti-inflammatory effects. In comparison to the standards, SCL revealed a comparable binding interaction with COX-1 and COX-2 receptors in the molecular docking study. Furthermore, SCL displayed remarkable pharmacokinetic characteristics. In conclusion, SCL significantly and dose-dependently reduced the number of paw licks and edema diameters in animals. Thus, SCL may be responsible for producing an anti-inflammatory effect by interacting with COX-1 and COX-2 receptors.

Sclareol exerts synergistic antidepressant effects with quercetin and caffeine, possibly suppressing GABAergic transmission in chicks

This study evaluated the effects of sclareol (SCL) with or without caffeine (CAF) and quercetin (QUR) using in-vivo and in-silico studies. For this, 5-day-old chicks weighing between 45 and 48 g were randomly divided into five groups and treated accordingly. The chicks were monitored to compare the occurrence, latency, and duration of sleep as well as the loss and gain of righting reflex in response to SCL-10 mg/kg, CAF-10 mg/kg, and QUR-50 mg/kg using a thiopental sodium (TS)-induced sleeping model. Data were analyzed by one-way ANOVA followed by t-Student–Newman-Keuls' as a posthoc test at 95% confidence intervals with multiple comparisons. An in-silico study was also performed to investigate the possible antidepressant mechanisms of the test and/or standard drugs with different subunits of GABAA receptors. In comparison to the SCL, CAF, and QUR individual groups, SCL+CAF+QUR significantly increased the latency while decreasing the length of sleep. The incidence of loss and gain of the righting reflex was also modulated in the combination group. SCL showed better interaction with GABAA (α2 and α5) subunits than QUR with α2, α3, and α5. All these compounds showed stronger interactions with the GABAA receptor subunits than the standard CAF. Taken together, SCL, CAF, and QUR reduced the TS-induced righting reflex and sleeping time in the combination group more than in the individual treatments. SCL may show its antidepressant effects, possibly through interactions with GABAA receptor subunits.

Antiemetic effects of sclareol, possibly through 5-HT3 and D2 receptor interaction pathways: In-vivo and in-silico studies

BackgroundEmesis is a complex physiological phenomenon that serves as a defense against numerous toxins, stressful situations, adverse medication responses, chemotherapy, and movement. Nevertheless, preventing emesis during chemotherapy or other situations is a significant issue for researchers. Hence, the majority view contends that successfully combining therapy is the best course of action. In-vivo analysis offers a more comprehensive grasp of how compounds behave within a complex biological environment, whereas in-silico evaluation refers to the use of computational models to forecast biological interactions. ObjectivesThe objectives of the present study were to evaluate the effects of Sclareol (SCL) on copper sulphate-induced emetic chicks and to investigate the combined effects of these compounds using a conventional co-treatment approach and in-silico study. MethodsSCL (5, 10, and 15 mg/kg) administered orally with or without pre-treatment with anti-emetic drugs (Ondansetron (ODN): 24 mg/kg, Domperidone (DOM): 80 mg/kg, Hyoscine butylbromide (HYS): 100 mg/kg, and Promethazine hydrochloride (PRO): 100 mg/kg) to illustrate the effects and the potential involvement with 5HT3, D2, M3/AChM, H1, or NK1 receptors by SCL. Furthermore, an in-silico analysis was conducted to forecast the role of these receptors in the emetic process. ResultsThe results suggest that SCL exerted a dose-dependent anti-emetic effect on the chicks. Pretreatment with SCL-10 significantly minimized the number of retches and lengthened the emesis tendency of the experimental animals. SCL-10 significantly increased the anti-emetic effects of ODN and DOM. However, compared to the ODN-treated group, (SCL-10 + ODN) group considerably (p < 0.0001) extended the latency duration (109.40 ± 1.03 s) and significantly (p < 0.01) decreased the number of retches (20.00 ± 0.70), indicating an anti-emetic effect on the test animals. In in-silico analysis, SCL exhibited promising binding affinities with suggesting receptors. ConclusionSCL-10 exerted an inhibitory-like effect on emetic chicks, probably through the interaction of the 5HT3 and D2 receptors. Further studies are highly appreciated to validate this study and determine the precise mechanism(s) behind the anti-emetic effects of SCL. We expect that SCL-10 may be utilized as an antiemetic treatment in a single dosage form or that it may function as a synergist with other traditional medicines.

Sclareol induces cell cycle arrest and ROS-mediated apoptosis and ferroptosis in lung adenocarcinoma cells.

Sclareol (SC) has shown significant anticancer activity against breast and colon cancers among others. However, its ability to precipitate similar anticancer effects in lung cancer has yet to be investigated. To address this issue, SC-treated lung adenocarcinoma cells (A549) were assessed for viability and functional competence as well as the expression of genes related to apoptosis and cell cycling. Our results demonstrated that SC treatment inhibited A549 cell clonogenic features and reduced their migration and invasion potential in a dose-dependent manner. Mechanistically, SC treatment downregulated the expression of cyclin D1 and survivin and upregulated that of p21 and p16, which was associated with a significant increase in the percentage of SubG0 cells. SC treatment is also associated with the induction of both the extrinsic and intrinsic apoptotic pathways, as evidenced by the increased expression and splitting of PARP1 and procaspases 3 and 9 and the reduced expression of antiapoptotic proteins Bcl-2 and Bcl-xL. Increased cell death in SC-treated cells is likely to have resulted from the induction of ferroptosis as suggested by the reduced expression of FPN and the inhibition of the anti-ferroptosis regulator GPX4. In conclusion, the data presented here suggest that SC can reduce lung carcinoma cell growth and metastasis and promote cell death.

Novel hybrids of sclareol and 1,2,4-triazolo[1,5-a]pyrimidine show collateral sensitivity in multidrug-resistant glioblastoma cells

The synthesis of 24 hybrid molecules, consisting of naturally occurring sclareol (SCL) and synthetic 1,2,4-triazolo[1,5-a]pyrimidines (TPs), is described. New compounds were designed with the aim of improving the cytotoxic properties, activity, and selectivity of the parent compounds. Six analogs (12a-f) contained 4-benzylpiperazine linkage, while 4-benzyldiamine linkage was present in eighteen derivatives (12g-r and 13a-f). Hybrids 13a-f consist of two TP units. After purification, all hybrids (12a-r and 13a-f), as well as their precursors (9a-e and 11a-c), were tested on human glioblastoma U87 cells. More than half of the tested synthesized molecules, 16 out of 31, caused a significant reduction of U87 cell viability (more than 75% reduction) at 30 µM. The concentration-dependent cytotoxicity of these 16 compounds was also examined on U87 cells, corresponding multidrug-resistant (MDR) U87-TxR cells with increased P-glycoprotein (P-gp) expression and activity, and normal lung fibroblasts MRC-5. Importantly, 12l and 12r were active in the nanomolar range, while seven compounds (11b, 11c, 12i, 12l, 12n, 12q, and 12r) were more selective towards glioblastoma cells than SCL. All compounds except 12r evaded MDR, showing even better cytotoxicity in U87-TxR cells. In particular, 11c, 12a, 12g, 12j, 12k, 12m, 12n, and SCL showed collateral sensitivity. Hybrid compounds 12l, 12q, and 12r decreased P-gp activity to the same extent as a well-known P-gp inhibitor - tariquidar (TQ). Hybrid compound 12l and its precursor 11c affected different cellular processes including the cell cycle, cell death, and mitochondrial membrane potential, and changed the levels of reactive oxygen and nitrogen species (ROS/RNS) in glioblastoma cells. Collateral sensitivity towards MDR glioblastoma cells was caused by the modulation of oxidative stress accompanied by inhibition of mitochondria.

Sclareol attenuates liver fibrosis through SENP1-mediated VEGFR2 SUMOylation and inhibition of downstream STAT3 signaling.

Liver fibrosis is a key global health care burden. Sclareol, isolated from Salvia sclarea, possesses various biological activities. Its effect on liver fibrosis remains unknown. This study was proposed to evaluate the antifibrotic activity of sclareol (SCL) and explore its underlying mechanisms. Stimulated hepatic stellate cells served as an in vitro liver fibrosis model. The expression of fibrotic markers was assessed by western blot and real-time PCR. Two classical animal models, bile duct-ligated rats and carbon tetrachloride-treated mice, were utilized for the in vivo experiments. The liver function and fibrosis degree were determined by serum biochemical and histopathological analyses. VEGFR2 SUMOylation was analyzed using coimmunoprecipitation assay. Our results indicated that SCL treatment restricted the profibrotic propensity of activated HSCs. In fibrotic rodents, SCL administration alleviated hepatic injury and reduced collagen accumulation. Mechanistic studies indicated that SCL downregulated the protein level of SENP1 and enhanced VEGFR2 SUMOylation in LX-2 cells, which affected its intracellular trafficking. Blockade of the interaction between VEGFR2 and STAT3 was observed, resulting in the suppression of downstream STAT3 phosphorylation. Our findings demonstrated that SCL has therapeutic efficacy against liver fibrosis through mediating VEGFR2 SUMOylation, suggesting that SCL may be a potential candidate compound for its treatment.

Synergistic inhibitory effect of α-humulene and sclareol on human pancreatic cancer cells

• α-Humulene and sclareol showed synergistic inhibitory effect on human pancreatic cancer cells. • The combination strongly decreased the levels of NF-κB, phosphor Akt (pAkt) and Bcl-2, and increased the level of Bax. • The in vivo study showed that HUM and SCL in combination suppressed the growth of Panc-1 xenograft tumors in immunodeficient mice. Both α-Humulene (HUM) and sclareol (SCL) are naturally occurred compounds and have been shown to exert anti-inflammatory and anticancer activities. The effects of these two compounds alone or in combination on pancreatic cancer cells have not been reported. In the present study, we investigated the effects of HUM and SCL on human pancreatic cancer cells cultured in vitro and grown as xenograft tumors in vivo. In the in vitro studies, we found that HUM and SCL in combination synergistically inhibited the growth of pancreatic cancer cells. The combination strongly stimulated apoptosis, and suppressed migration, invasion and sphere formation in pancreatic cells. Studies on the mechanism of action showed that the combination strongly decreased the levels of NF-κB, phosphor Akt (pAkt) and Bcl-2, and increased the level of Bax. Knockdown of NF-κB and Akt by small interfering RNA (siRNA) abrogated the inhibitory effect of HUM and SCL on pancreatic cancer cells. The in vivo study showed that HUM and SCL in combination suppressed the growth of Panc-1 xenograft tumors in immunodeficient mice. Results of the present study indicate that HUM and SCL in combination may represent an effective approach for inhibiting the growth of pancreatic cancer.

Nanostructured lipid carriers as a novel tool to deliver sclareol: physicochemical characterisation and evaluation in human cancer cell lines

Sclareol (SC) is arousing great interest due to its cytostatic and cytotoxic activities in several cancer cell lines. However, its hydrophobicity is a limiting factor for its in vivo administration. One way to solve this problem is through nanoencapsulation. Therefore, solid lipid nanoparticles (SLN-SC) and nanostructured lipid carriers (NLC-SC) loaded with SC were produced and compared regarding their physicochemical properties. NLC-SC showed better SC encapsulation than SLN-SC and was chosen to be compared with free SC in human cancer cell lines (MDA-MB-231 and HCT-116). Free SC had slightly higher cytotoxicity than NLC-SC and produced subdiploid DNA content in both cell lines. On the other hand, NLC-SC led to subdiploid content in MDA-MB-231 cells and G2/M checkpoint arrest in HCT-116 cells. These findings suggest that SC encapsulation in NLC is a way to allow the in vivo administration of SC and might alter its biological properties

Sclareol is a potent enhancer of doxorubicin: Evaluation of the free combination and co-loaded nanostructured lipid carriers against breast cancer

AimsIn this work, it was sought to determine if there was synergism between doxorubicin (DOX), a well-known antineoplastic, and sclareol (SC), a diterpene from natural origin, in breast cancer treatment. Moreover, it was investigated if their co-loading in the same nanocarrier would result in a gain of activity and/or a toxicity diminishment. Main methodsThe synergism of the DOX:SC combination was evaluated in MDA-MB-231 and 4T1 cells. A nanostructured lipid carrier (NLC) co-encapsulating DOX and SC in their synergistic molar ratio was prepared and characterised, in terms of mean diameter, zeta potential, DOX encapsulation efficiency, small angle X-ray scattering, differential scanning calorimetry, and polarised light microscopy for further intravenous administration. The anticancer activity of the combination, free and encapsulated, was evaluated in 4T1-tumour bearing mice. Key findingsIt was determined that DOX:SC combination at the molar ratio 1:1.9 presents better synergistic anticancer activity than the molar ratio 1:7.5 in vitro. DOX:SC-loaded NLC (NLC-DOX-SC) improved in vitro cytotoxic and in vivo antitumour activity compared to free DOX. Although NLC-DOX-SC and free DOX:SC, at the synergistic molar ratio, showed similar activity in the in vivo study, the free combination provoked body weight loss, behaviour alterations and haematological toxicity in the animals, while this was not observed for NLC-DOX-SC. SignificanceThis work shows that SC and DOX present synergistic anticancer activity for breast cancer treatment whereas NLC-DOX-SC was a feasible alternative to attain the benefits posed by DOX:SC combination but with none to fewer side effects.

Improved Cytotoxic Effect of Doxorubicin by Its Combination with Sclareol in Solid Lipid Nanoparticle Suspension.

This work aims to develop, characterize, and evaluate the anticancer activity of solid lipid nanoparticles (SLN) containing doxorubicin (DOX), an antitumoral from the antracycline class, and sclareol (SC), a lipophilic labdene diterpene (SLN-DOX-SC). The SLN were characterized by Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Small Angle X-ray Diffraction (SAXS), in vitro release, transmission electron microscopy, and polarized light microscopy. Evaluation of cell viability was performed in two cell cultures: MCF-7 (human breast cancer) and 4T1 (murine breast cancer). The SLN showed a size in the range of 128 nm, negative zeta potential, DOX encapsulation efficiency (EE) of 99%, and drug loading (DL) of 66 mg/g. Characterization of the formulation by DSC, XRD, and SAXS revealed the presence of DOX inside the nanoparticles of SLN and suggested increased expulsion/release of this drug when associated with SC. The release profiles revealed that the SLN-DOX-SC showed controlled release of DOX at pH 7.4 with enhanced drug release at low pH, useful for cancer treatment. The SLN-DOX-SC demonstrated to be more effective than the free DOX against 4T1 cells. So, the developed SLN efficiently encapsulate DOX and SC and show good potential as an alternative for cancer treatment.

Abstract B49: Cancer cell spheroids as a model to study sequential chemotherapy protocols

Abstract This study aimed at comparing six combinations of priming drug / doxorubicin (DOX) in a spheroid model. Three-dimensional cultures of drug-resistant cancer cells (spheroids) are physiologically relevant[1] and have been used as models of limited drug penetration[2]. Enhanced tumor accumulation and therapeutic efficacy of liposomal DOX after apoptosis induction by paclitaxel (PTX) has been reported[3]. Moreover, mitochondrial depolarization is correlated with clinical response[4]. Here we proposed use of spheroids to evaluate sequential chemotherapy combinations for potentiation of DOX cytotoxicity after pretreatment with cytotoxic concentrations of clinically relevant drugs. To this aim, 400–500 μm NCI-ADR-RES (ovarian carcinoma) were used. We first incubated spheroids 48h with mitoxantrone (MXO), cisplatin (CIS), dexamethasone (DXM), methotrexate (MTX), sclareol (SCL) and PTX as first line (priming) agents at concentrations inducing a 1.5- to 2.5-fold lactate dehydrogenase (LDH) release compared to untreated cells. For DOX accumulation studies, these were further cultured in the presence of 25 μM of DOX during 24h before determination of DOX content (nanomoles DOX/mg of proteins) by fluorescence. For DOX cytotoxicity evaluation, pretreated spheroids were incubated 72h with 100 μM of DOX before assessment of viability with a Cytotox 96 nonradioactive cell viability kit (Promega). Three DOX forms were used: free drug (DOX), distearyl1,2-distearoyl-sn-glycero-3-phospho-ethanolamine-N-[amino(polyethylene glycol)-2000] / DOX micelles (MDOX, 13 nm) prepared according to [5, 6], and liposomal DOX (LDOX, Lipo-Dox®, 130 nm, Sun Pharma India). The accumulation pattern of these forms was DOX = MDOX &amp;gt; LDOX as previously reported[7]. We document enhanced DOX, MDOX and LDOX accumulation after spheroids pretreatment with mitoxantrone (2.8-; 1.8- and 2.5-fold, respectively) and increased distribution of DOX and MDOX in PTX primed spheroids (2- and 1.4-fold, respectively). CIS, DXM, SCL and MTX failed at enhancing free, micellar or liposomal DOX distribution in spheroids. Improved DOX accumulation obtained with MXO and PTX resulted in respectively 1.4- and 2.2-fold higher LDH release compared to spheroids treated only with DOX. Interestingly, although preincubation with SCL did not promote DOX, MDOX or LDOX accumulation, LDH release of spheroids cultured with SCL before DOX treatment was 2.5-fold higher than ones treated only with DOX. While LDOX toxicity was not increased by any pretreatment, viability of cells incubated with MDOX decreased further when pretreated with PTX and MXO (1.5- and 1.8-fold compared to MDOX respectively). Low LDOX toxicity is in agreement with [7] and may be due to insufficient DOX release[8]. We report for the first time use of spheroids to test DOX toxicity potentiation as free, micellar or liposomal forms. Out of the six inducers tested, three (PTX, MXO and SCL) enhanced DOX accumulation and/or toxicity. Results suggest different mechanisms of priming for these three drugs and support sequential chemotherapy with PTX, MXO or SCL and DOX. Acknowledgments: This work was supported by grant CCNE IUCA151881 to V.P. Torchilin.

Synthesis of nor-norambracetal

We describe the synthesis of nor-norambracetal 13 from sclareol 1, using γ-homobicyclo-farnesylic alcohol 3 as a key intermediate.

Further neo-clerodane diterpenoids from Stachys rosea

The known 13- epi-sclareol and the new neo-clerodanes roseostachenol and roseotetrol were isolated from Stachys rosea. Their structures were elucidated as 2α,13-dihydroxy- neo-cleroda-3,14-diene, resp. 2α,3α,4β,13-tetrahydroxy- neo-clerod-14-en.

Synthesis of norambracetal: A new ambergris derivative.

We describe the synthesis of norambracetal 14 from sclareol 1 using γ -homobicyclofarnesilic aldehyde 1O as a key intermediate.

Diterpenoids. X. cis- and trans-Biformene

cis- and trans-Biformene have been synthesized by the dehydration of abienol, manool, and sclareol. Both cis- and trans-biformene are naturally occurring hydrocarbons.

Structure of Tauranin and a Note on the "C&lt;SUB&gt;16&lt;/SUB&gt;-Acids" obtained from Di- and Triterpenoids

The structure of tauranin, a metabolic pigment from Oospora aurantia, has been established as shown by I. The relations of the three C16-acids derived from ambrein, sclareol, and manool have been clarified.