Rosemary Diterpenes Research Articles

Medicinal plant rosemary relaxes blood vessels by activating vascular smooth muscle KCNQ channels.

The evergreen plant rosemary (Salvia rosmarinus) has been employed medicinally for centuries as a memory aid, analgesic, spasmolytic, vasorelaxant and antihypertensive, with recent preclinical and clinical evidence rationalizing some applications. Voltage-gated potassium (Kv) channels in the KCNQ (Kv7) subfamily are highly influential in the nervous system, muscle and epithelia. KCNQ4 and KCNQ5 regulate vascular smooth muscle excitability and contractility and are implicated as antihypertensive drug targets. Here, we found that rosemary extract potentiates homomeric and heteromeric KCNQ4 and KCNQ5 activity, resulting in membrane hyperpolarization. Two rosemary diterpenes, carnosol and carnosic acid, underlie the effects and, like rosemary, are efficacious KCNQ-dependent vasorelaxants, quantified by myography in rat mesenteric arteries. Sex- and estrous cycle stage-dependence of the vasorelaxation matches sex- and estrous cycle stage-dependent KCNQ expression. The results uncover a molecular mechanism underlying rosemary vasorelaxant effects and identify new chemical spaces for KCNQ-dependent vasorelaxants.

Assessment of a Diterpene-Rich Rosemary (Rosmarinus officinalis L.) Extract as a Natural Antioxidant for Salmon Pâté Formulated with Linseed.

The use of natural plant extracts with standardised antioxidant properties is a growing strategy to stabilise food products. The use of a rosemary lipophilic extract (RLE), obtained from the by-product of high-yield selected plants and rich in polyphenols (334 mg/g, with diterpenes such as carnosic acid and carnosol as main compounds), is here proposed. Four RLE doses (0, 0.21, 0.42 and 0.63 g/kg) were tested in a salmon pâté formulated with sunflower oil and linseed, which was pasteurised (70 °C for 30 min) and subjected to storage at 4 °C and 600 lux for 42 days. Rosemary diterpenes resisted pasteurisation without degrading and showed antioxidant activities during the shelf-life of pasteurised pâté. RLE addition led to increased peroxide value (from 3.9 to 5.4 meq O2/kg), but inhibited formation of secondary oxidised lipids such as malondialdehyde (from 1.55 to 0.89 mg/g) and cholesterol oxidation products (from 286 to 102 µg/100 g) and avoided discolouration (slight brownness) in the refrigerated pâté. However, this did not entail relevant changes in fatty acid content or in the abundance of volatile organic compounds from oxidised lipids. Increasing the RLE dose only improved its antioxidant efficacy for some oxidation indexes. Thus, the oxidative deterioration of these types of fish emulsion can be naturally controlled with rosemary extracts rich in diterpenes.

Rosemary Diterpenes and Flavanone Aglycones Provide Improved Genoprotection against UV-Induced DNA Damage in a Human Skin Cell Model.

Overexposure to solar ultraviolet (UV) radiation is the major cause of a variety of cutaneous disorders, including sunburn, photoaging, and skin cancers. UVB radiation (290–320 nm) causes multiple forms of DNA damage, p53 induction, protein and lipid oxidation, and the generation of harmful reactive oxygen species (ROS). In recent years, botanicals containing polyphenols with antioxidant and anti-inflammatory properties as skin photoprotective agents have emerged. This study evaluated the protective effects of two formulations against UVB-induced damage in a skin cell model. One of the formulations (F2) contained a combination of citrus and olive extracts and the other one (F1) also contained a rosemary extract. The antioxidant capacity of both formulations was estimated by different in vitro methods, and the cell viability, intracellular ROS generation, mitochondrial depolarization, and DNA damage were studied in UVB-irradiated human keratinocytes. Both formulations exerted photoprotective effects on skin cells and decreased mitochondrial depolarization and DNA damage. F1 which contained iridoids, rosemary diterpenes, glycosides and aglycones of citrus flavanones, and monohydroxylated flavones exhibited higher cellular photoprotective effects and mitochondrial membrane potential restoration, as well as an enhanced capacity to decrease DNA double strand breaks and the DNA damage response. In contrast, F2, which contained mostly iridoids, citrus flavanone aglycones, and mono- and dihydroxylated flavones, exhibited a higher capacity to decrease intracellular ROS generation and radical scavenging capacity related to metal ion chelation. Both formulations showed a similar capability to decrease the number of apoptotic cells upon UVB radiation. Based on our results and those of others, we postulate that the stronger capacity of F1 to protect against UVB-induced DNA damage in human keratinocytes is related to the presence of rosemary diterpenes and citrus flavanone aglycones. Nevertheless, the presence of the dihydroxylated flavones in F2 may contribute to inhibiting the generation of metal-related free radicals. To confirm the efficacy of these formulations as potential candidates for oral/topical photoprotection, human trials are required to circumvent the limitations of the cellular model.

Enhancing Lipid Oxidative Stability of Cooked‐Chilled Lamb Meat through Dietary Rosemary Diterpenes

AbstractA dietary rosemary extract (DRE) containing carnosic acid and carnosol at 1:1 (w/w) for enhancing the lipid oxidative stability in cooked‐chilled lamb meat, is evaluated. Three diets for fattening lambs are tested: i) a cereal‐based concentrate (C‐diet); ii) the C‐diet plus 600 mg vitamin E per kg feed (E‐diet); and iii) the C‐diet plus 600 mg rosemary diterpenes per kg feed (R‐diet). Griddled‐chilled lamb patties are kept at 4 °C and lighting for 2 days, simulating catering conditions. Diterpenes have a lower deposition rate than vitamin E in lamb muscle and are completely degraded during cooking. DRE is thus less effective than dietary vitamin E in enhancing the oxidative stability of the patties. After 2‐day storage, the R‐diet shows lower (p < 0.01) peroxide values and thiobarbituric acid reactive substances than the C‐diet, while, in contrast to the E‐diet, it does not inhibit (p > 0.05) the formation of cholesterol oxidation products. The R‐diet increases (p < 0.05) the proportion of polyunsaturated fatty acids and decreases (p < 0.05) the n‐6/n‐3 ratio. These findings suggest antioxidant protection by dietary bioactive compounds beyond the direct radical scavenging activity that is able to stabilize lipids during the meat shelf‐life.Practical Applications: Cooked‐chilled meat lipids strongly oxidize in ready‐to‐eat dishes kept in retailing conditions, which may negatively affect their levels of polyunsaturated fatty acids (PUFA), cholesterol oxidation products (COP), and other lipid oxidation products. Dietary rosemary diterpenes can be used as a clean alternative to feed additives to enhance the oxidative stability of cooked‐chilled meat. Improved health and antioxidant status of the animal might be able to reduce oxidative spoilage during meat shelf‐life. Diterpenes provide lesser antioxidant protection than dietary vitamin E but may improve the PUFA content, with positive implications for the nutritional quality of lamb fat. The use of dietary antioxidants with different properties may contribute to improving the efficacy of animal feeds to improve meat quality.

Metabolomics study of early metabolic changes in hepatic HepaRG cells in response to rosemary diterpenes exposure

Rosemary diterpenes have demonstrated diverse biological activities, such as anti-cancer, antiinflammatory, as well as other beneficial effects against neurological and metabolic disorders. In particular, carnosic acid (CA), carnosol (CS) and rosmanol (RS) diterpenes have shown interesting results on anti-cancer activity. However, little is known about the toxic effects of rosemary diterpenes at the concentrations needed to exert their antiproliferative effect on cancer cells. In our study, CA, CS and RS exhibited a concentration-dependent effect on cell viability of two human colon cancer cell lines (HT-29 and HCT116) after 24 h exposure. HT-29 cell line was more resistant to the inhibitory effect of the three diterpenes than HCT116 cell line. Among the three diterpenes, RS exerted the strongest effect in both cell lines. To investigate the hepatotoxicity of CA, CS and RS, undifferentiated and differentiated HepaRG cells were exposed to increasing concentrations of the diterpenes (from 10 to 100 μM). Differentiated cells were found to be more resistant to the toxic activity of the three diterpenes than undifferentiated HepaRG, probably related to a higher detoxifying function of differentiated HepaRG cells compared with the undifferentiated cells. The metabolic profiles of differentiated HepaRG cells in response to CA, CS and RS were examined to determine biochemical alterations and deepen the study of the effects of rosemary phenolic diterpenes at molecular level. A multiplatform metabolomics study based on liquid- and gas-chromatography hyphenated to high resolution mass spectrometry revealed that rosemary diterpenes exerted different effects when HepaRG cells were treated with the same concentration of each diterpene. RS revealed a greater metabolome alteration followed by CS and CA, in agreement with their observed cytotoxicity. Metabolomics provided valuable information about early events in the metabolic profiles after the treatment with the investigated diterpenes from rosemary.

P 187 - Prevention of UVB-induced Oxidative Stress and DNA damage in human keratinocytes by citrus and olive formulations

Solar ultraviolet (UV) radiation, especially UVB (290 nm-320 nm) component, causes DNA damage, pyrimidine dimmers, 8-hydroxy-2´-deoxyguanosine (8-OHdG), p53 induction, protein oxidation and generation of reactive oxygen species (ROS). Some polyphenols show the ability to protect the skin from the adverse effects of UVB radiation, including the risk of skin cancers. This study evaluated the protective effects of formulations containing citrus, rosemary and olive polyphenols (F1 and F2) against UVB-induced damage in human keratinocytes. F1 contained citrus, rosemary diterpenes and olive polyphenols and F2 citrus and olive flavones. The antioxidant capacity was determined using the ROS-sensitive dye 2’,7’-dichlorofluorescein diacetate (DCF-DA). Late apoptosis, mitochondrial membrane potential (MMP) and H2A.X histone phosphorylation were measured using Muse Cell Analyzer. The treatment with both formulations suppressed UVB-induced ROS production, and decreased late apoptosis, cell depolarization and DNA damage by H2A.X assay. In conclusion, these results suggest that the compounds present in both formulations might contribute to the observed protective effect. Formulations may be considered as candidates for oral or topical photoprotection and their mechanism of action may deserve further attention.

P 188 - Antioxidant activity and photoprotective effect of citrus and olive formulations on UVB-induced damage in human keratinocytes

UV radiation, absorbed by the epidermis, is the major cause of a variety of cutaneous disorders including photoageing and skin cancers. In recent years, an increase in the use of botanicals with antioxidant and anti-inflammatory properties as skin photoprotective agents is emerging. This study evaluated the antioxidant activity and the protective effect of citrus and olive formulations (F1 and F2), against UVB-induced damage in human keratinocytes. F1 contained citrus, rosemary diterpenes and olive polyphenols and F2 citrus and olive flavones. Total phenolic content was determined with Folin-Ciocalteu. The antioxidant activity was evaluated with different methods: trolox equivalent antioxidant capacity (TEAC), ferric reducing-antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) assays. Photoprotection study was performed determining the viability of HaCaT cells exposed to UVB through MTT assay. The F1 showed higher phenolic content and antioxidant capacity. Both formulations also exhibited high protective effects on cell survival upon UVB radiation, finding a higher effect for F1 when both were used at same concentration. These results indicate that F1 may be considered as a better ingredient for oral or topical photoprotection. This suggests that, probably not only citrus and olive polyphenols but also rosemary compounds act in the protective action.

Incorporating rosemary diterpenes in lamb diet to improve microbial quality of meat packed in different environments.

The dietary use of phytochemicals may contribute to improving lamb meat preservation under different packing atmospheres. The objective was to test the preservative potential of a dietary rosemary extract (RE) containing carnosic acid and carnosol (at 1:1 w:w) in chilled lamb patties packed in air, vacuum and 70/30 O2 /CO2 modified atmosphere. Three experimental diets, (C) control, (RE) C plus 600mg RE/kg feed and (E) C plus 600mg vitamin E/kg, were given to fattening lambs. Unlike the C- and E-diets, the RE-diet had a double antimicrobial and antioxidant effect on the lamb patties packed in all the environments studied. The RE-diet inhibited total viable and lactic acid bacteria and Enterobacteriaceae, but not Brochothrix thermosphacta and Pseudomonas spp. and also improved oxidative stability (measured as CIE Lab color and thiobarbituric reagent substances), appearance and odor. The E-diet had a better antioxidant effect than the RE-diet but had no antimicrobial effects. Escherichia coli and Salmonella spp. were not detected. The dietary use of RE was most suitable for preserving vacuum-packed meat, which is more exposed to spoilage by anaerobic bacteria, while the use of dietary vitamin E allowed better control of oxidation in the meat packed in a bacteriostatic and oxidizing environment.

The Therapeutic Potential of Rosemary (Rosmarinus officinalis) Diterpenes for Alzheimer’s Disease

Rosemary (Rosmarinus officinalis L.) is one of the most economically important species of the family Lamiaceae. Native to the Mediterranean region, the plant is now widely distributed all over the world mainly due to its culinary, medicinal, and commercial uses including in the fragrance and food industries. Among the most important group of compounds isolated from the plant are the abietane-type phenolic diterpenes that account for most of the antioxidant and many pharmacological activities of the plant. Rosemary diterpenes have also been shown in recent years to inhibit neuronal cell death induced by a variety of agents both in vitro and in vivo. The therapeutic potential of these compounds for Alzheimer's disease (AD) is reviewed in this communication by giving special attention to the chemistry of the compounds along with the various pharmacological targets of the disease. The multifunctional nature of the compounds from the general antioxidant-mediated neuronal protection to other specific mechanisms including brain inflammation and amyloid beta (Aβ) formation, polymerisation, and pathologies is discussed.

Use of dietary rosemary diterpenes to inhibit rancid volatiles in lamb meat packed under protective atmosphere

The objective of the present study was to determine the inhibitory effect of dietary rosemary diterpenes on the formation of the volatile organic compounds (VOCs) responsible for rancid flavour in raw lamb meat. The lamb diet was supplemented during the fattening stage with two levels (200 and 400 mg/kg feed) of a dietary rosemary extract (DRE) containing carnosic acid and carnosol (1 : 1, w/w). The formation of VOCs (determined by headspace solid-phase microextraction at 40°C and MS) and odour deterioration (assessed by quantitative descriptive analysis) were monitored in meat fillets (longissimus dorsi-lumborum muscle) packed in a 70/30 O2/CO2 protective atmosphere and kept at 2°C for up to 14 days. The raw meat odour deteriorated under pro-oxidizing conditions due to the development of an incipient rancidity caused by the formation of volatiles from lipid oxidation. A total of 46 volatile compounds were determined in lamb headspace: 18 aldehydes, seven alcohols, seven organic acids, six ketones, four furan compounds, two benzene compounds, one ester and one terpenoid. The use of DRE contributed to inhibit VOC formation and rancidity. Heptanal, octanal, nonanal and 2-pentyl-furan were the only VOCs affected (P<0.05) by the diet at any storage time. In general, VOC formation rate during storage was lower (P<0.05) in the meat from lambs that received a diet supplemented with 400 mg DRE/kg feed than in the meat from lambs receiving no dietary supplementation. VOC inhibition was less effective when the dose of DRE was reduced to 200 mg/DRE kg, although it depended on the VOC analysed. The intensity of rancid odour correlated (P<0.05) with the values of 43 of the 46 VOCs. The highest coefficients were obtained for octanol and octanal (R>0.75; P<0.001), although similar values were obtained for the coefficients of a large number of carbonyl, alcohols and furan compounds, among other volatiles, which can be considered molecular markers of rancidity in raw lamb meat. Principal component analysis confirmed that the differences in the VOC profile make it possible to identify whether or not samples have been reinforced with dietary rosemary diterpenes. Thus, VOC profiling can be regarded as a useful tool for assessing the dietary treatments used in sheep to improve the oxidative stability of lamb meat.

The Dietary Components Carnosic Acid and Carnosol as Neuroprotective Agents: a Mechanistic View.

Carnosic acid (CA) and carnosol are the major diterpenes found in Rosmarinus officinalis (rosemary), a culinary spice. CA and carnosol account for over 90% of its anti-oxidant activity in rosemary leaves. The diterpenes exert anti-oxidant, anti-inflammatory, and anti-carcinogenic activities, and present neuroprotective effects in both in vitro and in vivo experimental models. In some cases, CA exerted protective effects upon neuronal cells more intensely than resveratrol or sulforaphane. Therefore, CA and carnosol demonstrate a potential pharmacological role for rosemary diterpenes in ameliorating mammalian brain redox status, among other parameters, as for instance the modulation of neuroinflammation. The aim of this review is to discuss the biological effects of CA and carnosol on neuronal and glial cells with focus on the mechanism of action of such diterpenes.

Antioxidant and antimicrobial effects of dietary supplementation with rosemary diterpenes (carnosic acid and carnosol) vs vitamin E on lamb meat packed under protective atmosphere

The antioxidant and antimicrobial effects on lamb meat of the dietary use of rosemary diterpenes and vitamin E were compared. Thirty fattening lambs were assigned to three diets: (C) control; (R) C plus 600mgkg−1 carnosic acid and carnosol at 1:1 w:w; or (E) C plus 600mgkg−1 α-tocopherol. The deposition of the dietary supplements in the muscle was determined. Microbial quality (total viable counts, Lactic Acid Bacteria, Enterobacteriaceae, Escherichia coli and Salmonella spp), oxidative stability (CIELab color, malondialdehyde and total carbonyls) and sensory attributes (appearance and odor) were determined in loin stored at 2°C under 70% O2/30% CO2 atmosphere. Microbial quality was ensured by packaging and chilling. The E-diet was more effective (P≤0.05) than the R-diet in preventing meat oxidation, although the latter had antimicrobial effects on meat. The shelf life of lamb (assessed as the loss of freshness) could be increased by 5 (R-diet) or 10 (E-diet) days.

Diterpenes from rosemary (Rosmarinus officinalis): Defining their potential for anti-cancer activity

Recently, rosemary extracts standardized to diterpenes (e.g. carnosic acid and carnosol) have been approved by the European Union (EU) and given a GRAS (Generally Recognized as Safe) status in the United States by the Food and Drug Administration (FDA). Incorporation of rosemary into our food system and through dietary selection (e.g. Mediterranean Diet) has increased the likelihood of exposure to diterpenes in rosemary. In consideration of this, a more thorough understanding of rosemary diterpenes is needed to understand its potential for a positive impact on human health. Three agents in particular have received the most attention that includes carnosic acid, carnosol, and rosmanol with promising results of anti-cancer activity. These studies have provided evidence of diterpenes to modulate deregulated signaling pathways in different solid and blood cancers. Rosemary extracts and the phytochemicals therein appear to be well tolerated in different animal models as evidenced by the extensive studies performed for approval by the EU and the FDA as an antioxidant food preservative. This mini-review reports on the pre-clinical studies performed with carnosic acid, carnosol, and rosmanol describing their mechanism of action in different cancers.

Relationship between antioxidant status and oxidative stability in lamb meat reinforced with dietary rosemary diterpenes

The relationship between the antioxidant status of fresh meat and oxidative stability of chilled-packed meat obtained from lambs fed on a diet supplemented with two different doses of a rosemary extract containing carnosic acid and carnosol was studied. The incorporation of rosemary extract in the lamb diet led to the deposition of functional levels of the diterpenic metabolite C19H22O3 in meat, which improved its stability against oxidation. The antioxidant status could be assessed through both the radical scavenging capacity (DPPH and TEAC) and the ferric reducing antioxidant power (FRAP). In general, antioxidant status values correlated better (P<0.05) with the changes in CIELAB colour, malondialdehyde and sensory scoring than with the changes in hexanal and protein carboxylation measured in the lamb cuts kept under protective atmosphere for up to 14days. The FRAP and DPPH assays were more suitable than the TEAC assay for predicting meat oxidation and any resulting discolouration and rancidity.

Use of dietary rosemary diterpenes to extend the preservation of sulphited-lamb products

The use of dietary antioxidants is proposed for enhancing the preservative effects of sulphite in minced lamb products. Lamb diet was supplemented with 400mg rosemary diterpenes (carnosic acid plus carnosol at 1:1 w:w ratio) per kg feed during the fattening stage. The patties were formulated combining meat from different sources (lambs given feed supplemented with rosemary extract and control lambs) and SO2 addition levels (0, 150, 300 and 450mgkg−1). Several physical–chemical (reflectance, pH, WHC, carbonyls and volatiles from lipid oxidation), microbial (viable and lactic acid bacteria and coliforms) and sensory (appearance and odor) traits were determined in patties kept at 2°C and packed under 70/30 O2/CO2 atmospheres. Dietary antioxidants extended the shelf life from 7.9 to 12.3 days in patties made with 450mgkg−1 SO2, but had little effect at lower SO2 doses. Greater inhibition of browning, lipid oxidation, odor deterioration and rancidity was achieved by using supplemented lamb. The processing of lamb meat reinforced with endogenous diterpenes from rosemary seems to be a promising strategy for manufacturing sulphited raw products.

Improving the sensory and oxidative stability of cooked and chill-stored lamb using dietary rosemary diterpenes.

Two dietary rosemary extracts (DREs) containing diterpenes (carnosic acid and carnosol at 1:1 and 2:1 w:w) were tested in fattening lambs to stabilize the sensory quality of cooked and chill-stored patties. A total of 63 lambs were fed freely for 80 ± 5 d with a basal diet supplemented or not with DRE. Minced leg meat from each lamb was used to make patty batches. The patties were cooked at 72 ºC for 2 min, aerobically packed, kept at 2 ºC for up to 4 d and then reheated. Sensory traits (color, odor, flavor, and texture), CIELab color, and lipid oxidation (assessed as TBARS) were determined. In a first experiment, the lamb diet was supplemented with 600 mg of 1:1-DRE or 2:1-DRE kg(-1) feed. The 1:1-DRE diet delayed discoloration, flavor deterioration, and rancidity, while the 2:1-DRE diet was ineffective in this respect. In a second experiment, 4 supplementation levels of 1:1-DRE (0, 200, 400, and 600 mg kg(-1) feed) were compared. Flavor deterioration was delayed when the lamb diet was supplemented with at least 400 mg 1:1-DRE kg(-1) feed. The effects of the diet on the odor, flavor, and color were corroborated by differences in TBARS and CIELab. The results obtained suggest that rosemary diterpenes and/or their active secondary compounds deposited in muscle can act as endogenous antioxidants in cooked lamb. The carnosol intake seems crucial in the antioxidant actions achieved through DRE. The use of rosemary antioxidants in animal feeding would allow meat-based dishes to be preserved longer without adding preservatives.

Expression of microRNA-15b and the glycosyltransferase GCNT3 correlates with antitumor efficacy of Rosemary diterpenes in colon and pancreatic cancer.

Colorectal and pancreatic cancers remain important contributors to cancer mortality burden and, therefore, new therapeutic approaches are urgently needed. Rosemary (Rosmarinus officinalis L.) extracts and its components have been reported as natural potent antiproliferative agents against cancer cells. However, to potentially apply rosemary as a complementary approach for cancer therapy, additional information regarding the most effective composition, its antitumor effect in vivo and its main molecular mediators is still needed. In this work, five carnosic acid-rich supercritical rosemary extracts with different chemical compositions have been assayed for their antitumor activity both in vivo (in nude mice) and in vitro against colon and pancreatic cancer cells. We found that the antitumor effect of carnosic acid together with carnosol was higher than the sum of their effects separately, which supports the use of the rosemary extract as a whole. In addition, gene and microRNA expression analyses have been performed to ascertain its antitumor mechanism, revealing that up-regulation of the metabolic-related gene GCNT3 and down-regulation of its potential epigenetic modulator miR-15b correlate with the antitumor effect of rosemary. Moreover, plasmatic miR-15b down-regulation was detected after in vivo treatment with rosemary. Our results support the use of carnosic acid-rich rosemary extract as a complementary approach in colon and pancreatic cancer and indicate that GCNT3 expression may be involved in its antitumor mechanism and that miR-15b might be used as a non-invasive biomarker to monitor rosemary anticancer effect.

Relationship between the Antioxidant Capacity and Effect of Rosemary (Rosmarinus officinalis L.) Polyphenols on Membrane Phospholipid Order

The antioxidant activity of rosemary (Rosmarinus officinalis L.) extracts is mainly due to phenolic abietane diterpenes and phenolic acids such as rosmarinic acid. In this study a comprehensive characterization of non-water-soluble and water-soluble extracts from rosemary was achieved by liquid chromatography coupled to electrospray and mass spectrometry. The antioxidant activity of these extracts and their respective major compounds (carnosic acid, carnosol, rosmadial, genkwanin, and rosmarinic acid) was analyzed and compared by using different in vitro systems. Whereas rosmarinic acid, carnosic acid, and carnosol exhibited similar antioxidant activity in a phospholipid membrane-free assay, carnosol behaved as an extremely potent antioxidant in a membrane-based assay (4-6 times stronger than the rest of the compounds). This differential antioxidant behavior suggests that factors other than the radical scavenging capability may be involved. All of the diterpenes induced severe effects on lipid order and packing of phospholipid model membranes. Rosmadial and carnosol decreased the number and/or mobility of water molecules located at the polar head group region of the membrane phospholipids as seen by Laurdan fluorescence spectroscopy. Carnosol also strongly enhanced lipid order at the hydrophobic core of the membrane. These effects throughout the bilayer correlated to the stronger antioxidant capacity of carnosol to inhibit lipid peroxidation. On the contrary, carnosic acid decreased membrane fluidity at deeper regions of the bilayer as measured by bilayer-to-micelle transition assay and self-quenching measurements by using octadecylrhodamine B. These effects may contribute to membrane stabilization and hindrance of radical propagation, which may cooperate with the electron donor ability of rosemary diterpenes in protecting the membranes against oxidative damage.