Effects of diets enriched in n-6 or n-3 fatty acids on cholesterol metabolism in older rats chronically fed a cholesterol-enriched diet

Anti-Pulmonary Fibrosis Activities of Triterpenoids from Oenothera biennis

Five new triterpenoids, oenotheralanosterols C-G (1–5), with seven known triterpenoidcompounds, namely 2α,3α,19α-trihydroxy-24-norurs4,12-dien-28-oic acid (6), 3β,23-dihydroxy-1-oxo-olean-12-en-28-oic acid (7), remangilone C (8), knoxivalic acid A (9), termichebulolide (10), rosasecotriterpene A (11), androsanortriterpene C (12), were extracted and separated from the dichloromethane part of Oenothera biennis L. The anti-pulmonary fibrosis activities of all the compounds against TGF-β1-induced damage tonormal human lung epithelial (BEAS-2B) cells were investigated in vitro. The results showed that compounds 1–2, 6, 8, and 11 exhibited significant anti-pulmonary fibrosis activities, with EC₅₀ values ranging from 4.7 μM to 9.9 μM.

Antiproliferative and antimicrobial efficacy of the compounds isolated from the roots of Oenothera biennis L

BACKGROUND

Oenothera biennis L., commonly known as evening primrose, harbours the flavonoids, steroids, tannins, fatty acids and terpenoids responsible for a diverse range of biological activity, such as antitumour, anti-arthritic and anti-inflammatory effects. In addition to the previous reports from aerial parts of this plant, studies related to antiproliferative or antimicrobial activity from the roots are warranted.

OBJECTIVE

To investigate antiproliferative and antimicrobial activity of compounds/mixture (1-8) isolated and characterized from the roots of O. biennis L. A possible mechanism of antiproliferative activity was also studied by targeting ornithine decarboxylase (ODC) and cathepsin D (CATD).

STUDY DESIGN

Antiproliferative efficacy of the compounds/mixture was examined in selected cancer cell lines along with their probable mechanism of action. The antimicrobial activity was also studied against selected microbes (bacteria and fungi).

METHODS

Antiproliferative potential was evaluated by MTT assay against selected cell lines. The mechanism of action was studied spectrophotometrically by targeting ODC and CATD using both an in-vitro and an in-silico approach. The antimicrobial efficiency was analysed using the disc diffusion and broth dilution methods.

KEY FINDINGS

Oenotheralanosterol B (3) and the mixture of oenotheralanosterol A and oenotheralanosterol B (4) exhibited antiproliferative activity against breast, hepatic, prostate and leukaemia cancer cell lines as well as in mouse macrophages (IC₅₀ 8.35-49.69 μg/ml). Oenotheralanosterol B (3) and the mixture of oenotheralanosterol A and oenotheralanosterol B (4) displayed a strong molecular interaction with succinate dehydrogenase (binding energy -6.23 and -6.84 kcal/mol and Ki 27.03 and 9.6 μm, respectively). Oenotheralanosterol A (1), oenotheralanosterol B (3) and mixture of oenotheralanosterol A and oenotheralanosterol B (4) potently inhibited the ODC activity with IC₅₀ ranging from 4.65 ± 0.35 to 19.06 ± 4.16 μg/ml and also showed a strong interaction with ODC (BE -4.17 to -4.46 kcal/mol). Oenotheralanosterol A (1), cetoleilyl diglucoside (2), oenotheralanosterol B (3), dihydroxyprenylxanthone acetylated (6) and dihydroxyprenylxanthone (7) inhibited CATD activity (IC₅₀ 3.95 ± 0.49 to 24.35 ± 2.89 μg/ml). The in-silico molecular interaction analysis of compounds with CATD revealed the non-specific interaction. A moderate antimicrobial activity was observed against selected microbes with a growth inhibition ranging from 6 to 14 mm and minimum inhibitory concentration between 125 and 500 μg/ml. Oenotheralanosterol B (3) and dihydroxyprenylxanthone acetylated (6) exhibited better antimicrobial activity with an MIC range from 62.50 to 500 μg/ml.

CONCLUSION

Oenotheralanosterol B (3) exhibited stronger antiproliferative and antimicrobial potential with respect to the other compounds tested, whereas oenotheralanosterol A (1) was a potent inhibitor of ODC and CATD. Hence, it is suggested that these in-vitro findings could be studied further in vivo for biological activity, safety evaluation and derivatization to enhance potency and efficacy.

Neuroprotective effects of phytosterol esters against high cholesterol-induced cognitive deficits in aged rat

Accumulating epidemiological and experimental studies have confirmed that a high-cholesterol diet is detrimental to cognitive performance in animal models.

Effect of Olive Oil-Fried Sardine Consumption on Liver Lipid Composition and Fatty Acid Cholesterol Esterification in Hypercholesterolemic Rats

PUFA n-3 diets have hypolipemic and cardiovascular protection properties, however their effects on liver lipids are not well established. This work aimed to find out the acceptability and effects of diets containing olive oil-fried sardines on serum cholesterol, liver lipid and fatty acids profile in hypercholesterolemic growing Wistar rats. Hypercholesterolemia was induced for three weeks by a casein plus DL-methionine, olive oil and cholesterol plus bovine bileas cholesterol-raising agent. Rats were later transferred for three weeks to semisynthetic diets containing casein plus DL-methionine and olive oil (CO), casein plus DLmethionine, olive oil and the cholesterol-raising agent (COC), sardines fried in olive oil (S), and sardines friedin olive oil and the cholesterol-raising agent (SC). SC or S diets were well accepted by the rats. The SC-diet markedly blocked and reversed the hypercholesterolemic induction of the cholesterol-raising agent. The cholesterol withdrawal decreased serum cholesterol in CO and S dietsby decreasing the serum non-HDL-cholesterol content but the S-diet totally normalised the serum cholesterol. Fried sardines did not change the triacylglycerol, free, esterified and total cholesterol contents of liver. Although long PUFA n-6 and PUFA n-3 were decreased by the dietary cholesterol, olive oil-fried sardine consumption maintained the docosahexaenoic acid and thedocosahexaenoic acid/linolenic acid ratio in liver and cholesterol ester fraction at a high level. Olive oil fried sardines blocked the hypercholesterolemic effect of the diet containing cholesterol and help normalising lipoprotein profile in a rather short period. The oleic acid esterification of cholesterol was kept high in all experimental diets as a mechanism to maintain the liver cholesterol ester/free cholesterol ratio as high as possible. The fat in the oliveoil-fried sardines was used similarly to the oleic acid by the liver of hypercholesterolemic rats but increased its PUFA n-3 content in the total liver and its cholesterol ester fraction.

Protective effects of sea spaghetti-enriched restructured pork against dietary cholesterol: effects on arylesterase and lipoprotein profile and composition of growing rats

There is a general assumption that seaweeds are hypocholesterolemics and antioxidants. However, controversial results suggest specific properties for each individual alga. This study aims to assess the effect of including Sea Spaghetti alga (S) in a restructured-pork (RP) diet, both enriched and not enriched with dietary cholesterol, on arylesterase (AE) activity and lipoprotein concentration and composition of Wistar rats. Four groups of 10 growing male Wistar rats were each fed a mix of 85% AIN-93M diet and 15% freeze-dried RP for 5 weeks. The control group (C) consumed control RP-C; the S group consumed RP-S with 5% seaweeds; the Chol-C group consumed the C diet but enriched with cholesterol (2.43%) and cholic acid (0.49%); the Chol-S group consumed the S diet but enriched with cholesterol and cholic acid. AE activity was five times higher (P<.01) in S compared with C rats, but three times lower in Chol-S compared with Chol-C rats (P<.01). The Chol-C diet induced hypercholesterolemia but reduced triglycerides (TG), giving rise to the presence of very low-density lipoprotein (VLDL) that was enriched in cholesterol. The Chol-S diet partially blocked (P<.001) the hypercholesterolemic induction of the Chol-C diet, and reduced TG levels (P<.05) with respect to S rats. The cholesterol supplementation increased total cholesterol, VLDL-cholesterol, and intermediate-density lipoprotein+LDL-cholesterol (IDL+LDL)-cholesterol (P<.001) in Chol-C rats, but the effect was lower in the Chol-S diet. In conclusion, RP-S increases the antioxidant capacity within a noncholesterol enriched diet while improving the lipoprotein profile within a cholesterol-enriched diet.

Effects of seaweed-restructured pork diets enriched or not with cholesterol on rat cholesterolaemia and liver damage

Seaweed enriched-restructured pork (RP) is a potential functional food. However, indications of adverse effects associated with herbal medications, which include among others liver failure, toxic hepatitis, and death have been reported. Cholesterol feeding produces hepatomegalia and fat liver infiltration. The effect of seaweed-RP diet, cholesterol-enriched or not, on plasma cholesterol, liver damage markers, structure, and cytochrome CYP4A-1 were evaluated after 5 wk. Eight rat groups were fed a mix of 85% AIN-93M rodent-diet plus 15% RP. The Cholesterol-control (CC), Cholesterol-Wakame (CW), Cholesterol-Nori (CN) and Cholesterol-Sea Spaghetti (CS) groups respectively consumed similar diets to control (C), Wakame (W), Nori (N), and Sea Spaghetti (S) but as part of hypercholesterolaemic diets. CN and CS significantly blocked the hypercholesterolaemic effect observed in CC group. After 5-wk, N and S diets increased the CYP4A-1 expression. However, seaweed-RPs were unable to reduce the histological liver alterations observed in CC group. Larger and more abundant hepatocellular alterations were found in CS and CN rats suggesting that the hypocholesterolaemic effects of these seaweed-RPs seem to be a two-edged sword as they increased liver damage. Future studies are needed to understand the involved mechanisms.

HILIC quantification of oenotheralanosterol A and B from Oenothera biennis and their suppression of IL-6 and TNF-α expression in mouse macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Evening primrose (Oenothera biennis L.) is a wild medicinal herb of Central American origin that is now globally widespread. Its traditional uses include treatment of rheumatoid arthritis and premenopausal pain both of which have an inflammatory component. The present study demonstrates the in vitro anti-inflammatory activity of three Oenothera biennis compounds.

MATERIALS AND METHODS

Oenotheralanosterol A and B (Oen-A & Oen-B) along with gallic acid (GA) were isolated and characterized using column chromatography and NMR. The compounds were tested with LPS stimulated peritoneal mouse macrophages assaying for suppression of IL-6, TNF-α and NO synthesis. An HILIC method for the simultaneous quantitation of GA, Oen-A, and Oen-B in Oenothera biennis plant material was also developed as a means of monitoring quality of plant material.

RESULTS

Significant inhibition of TNF-α and IL-6 by GA, Oen-A and Oen-B was observed (p<0.05). Inhibition was concentration dependent and no synergistic or antagonistic effect on pro-inflammatory cytokines was found when used in combination (1:1) (p>0.05). The HILIC analysis method was validated using Oenothera biennis root.

CONCLUSION

The study demonstrates the anti-inflammatory activity of Oenothera biennis root compounds and supports its traditional use in arthritis management. Active anti-inflammatory compounds were identified and quantified by the HILIC method.

Effects of Nori- and Wakame-enriched meats with or without supplementary cholesterol on arylesterase activity, lipaemia and lipoproteinaemia in growing Wistar rats

Some seaweeds exert antioxidant and hypocholesterolaemic properties. The effects of diets including restructured meats (RM) containing Wakame (W) or Nori (N) algae on arylesterase (AE) activity and lipoprotein concentration and composition were tested. In the present study, six groups of ten male growing Wistar rats each were fed a mix of 85 % AIN-93M diet and 15 % freeze-dried RM for 35 d. The control group (C) consumed control RM, the W and N groups consumed RM with 5 % W and 5 % N, respectively. The cholesterol-enriched C (CC), W (CW) and N (CN) groups consumed their corresponding basal diets with supplementary cholesterol (2·43 %) and cholic acid (0·49 %). Cholesterol in the diet induced lower (P < 0·001) growth ratios. Both W and N diets significantly increased AE activity. VLDL-cholesterol values were lower in N rats than in W rats. AE activity increased (P < 0·001) in CC and CW rats but not in CN rats compared with their corresponding counterparts. AE was lower (P < 0·05) in the CN group than in the CC and CW groups. The CN diet partially blocked (P < 0·001) the hypercholesterolaemic induction observed in CC and CW diets and reduced TAG levels (at least P < 0·05) with respect to those of CC rats. Although dietary cholesterol supplementation increased total cholesterol, VLDL-cholesterol and (intermediate-density lipoprotein+LDL)-cholesterol (all P < 0·001) in all rats, the CN diet moderately improved the lipoprotein profile of hypercholesterolaemic rats. Changes in AE activity and plasma cholesterol in CN rats but not in CW rats suggest a possible relationship between the two parameters. It is concluded that inclusion of RM enriched with N may be used in hypercholesterolaemic diets to improve lipoprotein metabolism.

α-Linolenic acid but not conjugated linolenic acid is hypocholesterolaemic in hamsters

Conjugated linolenic acid (CLN) refers to a group of octadecatrienoic acid isomers that have three double bonds in conjugation. Both pomegranate and tung seed oils are rich in CLN but the major isomer in the former iscis9,trans11,cis13 while in the latter it iscis9,trans11,trans13. The present study examined the effects of CLN, isolated from either pomegranate seed oil or tung seed oil, and α-linolenic acid (LN), isolated from flaxseed oil, on serum cholesterol levels in male hamsters (body weight 105 g; age 10 weeks) fed a 0.1 % cholesterol and 10 % lard diet, for a period of 6 weeks. All hamsters were allowed free access to food and fluid. The blood samples were taken by bleeding from the retro-orbital sinus into a heparinized capillary tube under light ether anaesthesia after overnight fasting at weeks 0, 2, 4 and 6. It was found that supplementation of CLN at levels of 12.2–12.7 g/kg diet exhibited no significant effect on serum cholesterol level while LN at a similar level of supplementation had serum cholesterol reduced by 17–21 % compared with the control diet containing no LN and CLN. Supplementation of CLN and LN significantly decreased hepatic cholesterol but no effect was observed on heart and kidney cholesterol levels. It was concluded that LN possessed hypocholesterolaemic activity while CLN had no effect on blood cholesterol, at least in hamsters.

Differential effects of konbu and nori seaweed dietary supplementation on liver glutathione status in normo- and hypercholesterolaemic growing rats

The effects of six balanced diets for 3 weeks on dietary intake, growth, liver weight and fat, plasma cholesterol, total antioxidant capacity, liver glutathione status and antioxidant enzymes in growing male Wistar rats were studied. Ten rats per group were fed casein- and soyabean-based diets with or without 2.4 % cholesterol-raising agent. Seven percent of the diet consisted of a cellulose-wheat starch mix (35:65; control diets), freeze-dried nori (nori diets) or konbu (konbu diets). The 7 % dietary supplement of seaweeds was well accepted and induced normal growth rates in rats. Except for food intake, total and reduced glutathione and total antioxidant capacity, dietary cholesterol addition significantly affected (at least P<0.05) all parameters studied. Alga consumption affected total and reduced glutathione, glutathione reductase activity, plasma cholesterol, and total and cholesterol-adjusted total antioxidant capacity (at least P<0.05). A significant cholesterol-alga interaction was found for liver weight, total glutathione peroxidase (GSH-Px) and the Se-dependent GSH-Px:total GSH-Px ratio (at least P<0.05). GSH-Px activity increased in cholesterol-fed nori rats mainly as Se-dependent GSH-Px, while in konbu and control groups the GSH-Px activity was related to increases in both non-Se-dependent and Se-dependent GSH-Px activities. The decrease in the antioxidant status of konbu rats was related to the high As content of this alga, which led to a compensatory increase in glutathione reductase activity in these animals. In conclusion, although some antioxidant compounds are present in algae, other dietary compounds, such as As, induced poor antioxidant status in rats.

Dietary restriction counteracts age-related changes in cholesterol metabolism in the rat

The effects of ageing on the metabolism of cholesterol were examined in three different organs (liver, aorta and brain) of 6-, 12- and 24-month-old male Sprague-Dawley rats. Ageing was associated with a significant increase in intracellular cholesterol esters in all three organs. Steady state mRNA levels of multidrug resistance protein (MDR) and acylCoA:cholesterol acyl transferase (ACAT), enzymes involved in cholesterol import and esterification, were also increased. By contrast, expression of mRNA for neutral cholesterol ester hydrolase (nCEH) and caveolin-1, proteins involved in cholesterol ester hydrolysis and export, were significantly reduced. Dietary restriction is the only intervention shown to extend lifespan and retard age-related declines in function in mammals. To further explore the possible correlation between changes in cholesterol esterification and ageing, we analysed cholesterol metabolism in liver, aorta, and brain of aged rats exposed to two dietary restriction regimens: intermittent (alternate-day) fasting (IF) and food intake restriction (60% of ad libitum feeding). Both dietary regimens attenuated the age-related changes in cholesterol esters and in the expression of genes involved in cholesterol metabolism. These results provide evidence that distinctive age-associated changes in intracellular cholesterol metabolism occur in rats. Furthermore, these modifications can be partially reversed by dietary restriction, a condition known to affect the ageing process. Age-related changes in cholesterol metabolism may play a role in triggering and/or aggravating senescence-related disorders characterized by altered cholesterol homeostasis.

Fat and protein from olive oil-fried sardines interact to normalize serum lipoproteins and reduce liver lipids in hypercholesterolemic rats

Fatty fish consumption has been recommended due to its high (n-3) PUFA content. However, an effect of its protein on serum lipids and lipoproteins has also been suggested. The present study was designed to determine the acceptability of diets containing sardines fried in olive oil or the fat extracted from those sardines and the normalization of serum lipids and lipoproteins, the hepatic lipid profile, and the fatty acid composition of the liver of growing Wistar rats fed these diets after dietary loading of cholesterol. Hypercholesterolemia was induced for 3 wk by feeding rats a casein/olive oil/cholesterol diet. Rats were then switched for 2 wk to cholesterol-free purified diets containing casein plus olive oil (CO), sardines fried in olive oil (S) and casein plus the fat extracted from sardines fried in olive oil (CSF). The S and CSF diets were well accepted by the rats. Withdrawal of dietary cholesterol markedly reduced (P < 0.05) serum cholesterol level in all of the groups, but the S group had the greatest decrease and the CO group the smallest decrease. The S group had a more normal lipoprotein profile, in which HDL was the major lipid carrier, whereas rats of the CO group still had beta-VLDL particles. CSF-fed rats had an intermediate profile. Liver fat and total, free and esterified cholesterol levels were lower (P < 0,05) in the S group than in the other two groups. The S and CSF diets increased (P < 0.05) the (n-3) PUFA content in hepatic triacylglyceride, cholesterol ester and phospholipid fractions. The liver fatty acid profile of the S group was more normalized than those of the other two groups. These findings suggest that the inclusion in the diet of whole sardines fried in olive oil normalizes cholesterol metabolism in hypercholesterolemic rats more quickly than consumption of their extracted fat.