Evening primrose oil reduces urinary calcium excretion in both normal and hypercalciuric rats

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 dietary fats on bone health in advanced age

Evidence is accumulating that dietary lipids play an important role in bone health. Most of the data supporting the effects of lipids on bones have been collected in young adult and/or developing animals. Based upon this work, mechanisms have been proposed to explain how lipids act to enhance or inhibit bone resorption and deposition. Little work, however, has been done in older models. Since osteoporosis primarily afflicts the elderly, such work is needed in order to determine if mechanisms relevant to the young differ in advanced age, and to develop effective interventions for this especially vulnerable segment of the population. This article reviews evidence that dietary lipids are important to bone health in older individuals, and describes possible mechanisms that may be of particular relevance to the elderly. Specifically, studies supporting the influence of dietary lipids on calcium excretion, growth hormone secretion, fatty acid metabolism, and osteoblast formation are reviewed.

Gamma-linoleic acid and ascorbate improves skeletal ossification in offspring of diabetic rats

Maternal diabetes causes a range of complications in offspring, including reduced skeletal ossification. This study examined whether feeding gamma-linoleic acid (GLA) and ascorbate, alone or in combination, to diabetic pregnant rats improves skeletal development in their offspring. In addition, Ca(2+) concentration was monitored in maternal plasma and fetal tissue, as well as placental mRNA expression of calbindin-D(9k). Female rats rendered diabetic with streptozotocin were fed GLA (500 mg/kg/d), ascorbate (290 mg/kg/d), ascorbyl-GLA (790 mg/kg/d), or GLA and ascorbate (500 and 290 mg/kg/d, respectively) throughout pregnancy. Fetal skeletons were studied after alizarin red staining. Fewer ossification centers were observed in offspring of diabetic rats compared with offspring of control rats (68 +/- 4% of control, p = 0.01). An almost complete restoration of ossification occurred with all the treatments (92-95 +/- 3% of control). The effects of treatment on fetal ossification could not be explained by altered maternal plasma Ca(2+) concentrations or by mRNA expression of the placental Ca(2+)-transporting protein calbindin-D(9K). We conclude that GLA and/or ascorbate treatment was effective against diabetes-induced fetal ossification defects by a mechanism not related to placental Ca(2+) supply.

Oestrogen and essential fatty acid supplementation corrects bone loss due to ovariectomy in the female Sprague Dawley rat

Essential fatty acid deficient animals develop osteoporosis. Eicosapentaenoic acid and gamma-linoleic acid have been reported to have positive effects on bone metabolism in both the growing male rat and the ovariectomized (OVX) female rat. These effects have been further investigated using a novel gamma-linolenic/eicosapentaenoic acid diester together with an oestrogen implant in the ovariectomized, female Sprague Dawley rat. Rats were sham-operated or ovariectomized at age 11 weeks. Two groups of OVX rats received an oestrogen implant at ovariectomy. Animals received fatty acids, linoleic acid (control) or a diester with gamma-linolenic acid and eicosapentaenoic acid as part of a semi-synthetic diet. Bone calcium content and excretion of deoxypyridinolines as marker of bone degradation were measured at 14 weeks. Oestrogen, as well as diester alone, increased calcium/femur to sham levels. Oestrogen plus diester potentiated the effect of oestrogen on bone calcium (P < 0.05 vs OVX). At the same time, oestrogen alone and the combination of oestrogen plus diester significantly reduced (P < 0.05 vs OVX) urinary deoxypyridinoline and hydroxyproline excretion. Again, the diester potentiated the effect of oestrogen. The effects of the diester alone, together with the potentiated effects of oestrogen by the essential fatty acids on osteoporosis, are novel findings.

Cytokine levels affected by gamma-linolenic acid

This study was undertaken to assess whether gamma-linolenic acid (GLA) in the form of evening primrose oil (EPO) could affect rat serum cytokines, interferon-gamma (IFN-gamma), monocyte chemotactic protein-1 (MCP-1) and tumour necrosis factor-alpha (TNF-alpha). The following diets were administered: control, glucan, Freund's adjuvant and glucan plus Freund's adjuvant with and without GLA. In the presence of GLA, the IFN-gamma and MCP-1 levels were significantly decreased in contrast to the control group of TNF-alpha, which was significantly stimulated. On account of interaction between diets and GLA, the remaining diet groups of TNF-alpha were either not affected or were inhibited in the presence of GLA. The observations indicate that GLA may modulate the level of serum IFN-gamma, MCP-1 and TNF-alpha, which may be a worthwhile line of treatment in certain human diseases.

Ectopic calcification of rat aortas and kidneys is reduced with n-3 fatty acid supplementation

Supplementation with essential fatty acids has been shown to prevent the experimentally induced ectopic calcification of the kidneys known as nephrocalcinosis. Male Sprague-Dawley rats were fed a semi-synthetic diet supplemented with different essential fatty acids while being injected for a period of 10 days with calcium glubionate. After 3 weeks their kidneys and aorta were removed and the respective calcium content measured compared to the control, saline injected animals. Lipoic acid-EPA, fish oil (EPA rich) as well as the EPA monoester reduced the calcium concentration of both the kidneys and the aorta towards control values. Lipoic-EPA was the best absorbed of the three compounds and its combination of anti-oxidant together with EPA lowered the calcium content of both the aortas and the kidneys.

Calcium metabolism, osteoporosis and essential fatty acids: a review

Essential fatty acid (EFA)-deficient animals develop severe osteoporosis coupled with increased renal and arterial calcification. This picture is similar to that seen in osteoporosis in the elderly, where the loss of bone calcium is associated with ectopic calcification of other tissues, particularly the arteries and the kidneys. Recent mortality studies indicate that the ectopic calcification may be considerably more dangerous than the osteoporosis itself, since the great majority of excess deaths in women with osteoporosis are vascular and unrelated to fractures or other bone abnormalities. EFAs have now been shown to increase calcium absorption from the gut, in part by enhancing the effects of vitamin D, to reduce urinary excretion of calcium, to increase calcium deposition in bone and improve bone strength and to enhance the synthesis of bone collagen. These desirable actions are associated with reduced ectopic calcification. The interaction between EFA and calcium metabolism deserves further investigation since it may offer novel approaches to osteoporosis and also to the ectopic calcification associated with osteoporosis which seems to be responsible for so many deaths.