The Anti-Inflammatory, Phytoestrogenic, and Antioxidative Role of Labisia pumila in Prevention of Postmenopausal Osteoporosis.

Osteoporosis is characterized by skeletal degeneration with low bone mass and destruction of microarchitecture of bone tissue which is attributed to various factors including inflammation. Women are more likely to develop osteoporosis than men due to reduction in estrogen during menopause which leads to decline in bone-formation and increase in bone-resorption activity. Estrogen is able to suppress production of proinflammatory cytokines such as IL-1, IL-6, IL-7, and TNF-α. This is why these cytokines are elevated in postmenopausal women. Studies have shown that estrogen reduction is able to stimulate focal inflammation in bone. Labisia pumila (LP) which is known to exert phytoestrogenic effect can be used as an alternative to ERT which can produce positive effects on bone without causing side effects. LP contains antioxidant as well as exerting anti-inflammatory effect which can act as free radical scavenger, thus inhibiting TNF-α production and COX-2 expression which leads to decline in RANKL expression, resulting in reduction in osteoclast activity which consequently reduces bone loss. Hence, it is the phytoestrogenic, anti-inflammatory, and antioxidative properties that make LP an effective agent against osteoporosis.

The anti-inflammatory role of vitamin e in prevention of osteoporosis.

There is growing evidence that inflammation may be one of the causal factors of osteoporosis. Several cytokines such as IL-1, IL-6, RANKL, OPG, and M-CSF were implicated in the pathogenesis of osteoporosis. These cytokines are important determinants of osteoclast differentiation and its bone resorptive activity. Anticytokine therapy using cytokine antagonists such as IL-receptor antagonist and TNF-binding protein was able to suppress the activity of the respective cytokines and prevent bone loss. Several animal studies have shown that vitamin E in the forms of palm-derived tocotrienol and α-tocopherol may prevent osteoporosis in rat models by suppressing IL-1 and IL-6. Free radicals are known to activate transcription factor NFκB which leads to the production of bone resorbing cytokines. Vitamin E, a potent antioxidant, may be able to neutralise free radicals before they could activate NFκB, therefore suppressing cytokine production and osteoporosis. Vitamin E has also been shown to inhibit COX-2, the enzyme involved in inflammatory reactions. Of the two types of vitamin E studied, tocotrienol seemed to be better than tocopherol in terms of its ability to suppress bone-resorbing cytokines.

Effect of 11ß-HSD1 dehydrogenase activity on bone histomorphometry of glucocorticoid-induced osteoporotic male Sprague-Dawley rats.

INTRODUCTION: Glucocorticoids cause osteoporosis by decreasing bone formation and increasing bone resorption activity. Glucocorticoid action in bones depends on the activity of 11-beta-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) enzyme, which plays an important role in regulating corticosteroids. 11ß-HSD1 is expressed by human and rat osteoblasts. We aimed to investigate the relationship between 11ß-HSD1 dehydrogenase activity and bone histomorphometric changes in glucocorticoid-induced osteoporotic bone in rats. METHODS: A total of 30 male Sprague-Dawley rats (aged three months, weighing 200-250 g) were divided into three groups of ten each. Group 1 rats were the baseline control, which were sacrificed untreated at the beginning of the study. Group 2 rats underwent sham operation and were administered with vehicle olive oil intramuscularly at 0.05 ml/kg. Group 3 rats were adrenalectomised and administered with an intramuscular injection of dexamethasone 120 µg/kg body weight/day. The treatment was started two weeks after the operation, for a duration of two months. Plasma osteocalcin, plasma pyrodinoline, plasma corticosterone and 11ß-HSD1 were measured, and bone histomorphometry analysis was performed. RESULTS: Dexamethasone treatment caused an increase in plasma corticosterone level, together with a significant reduction in 11ß-HSD1 dehydrogenase activity of the bone, along with a higher plasma level of the bone resorption marker, pyridinoline. Dexamethasone treatment also caused a reduction in trabecular volume, number and thickness, and an increase in trabecular separation. CONCLUSION: Long-term glucocorticoid treatment reduces the 11ß-HSD1 dehydrogenase activity in the bone, which can otherwise lead to bone loss due to the increased level of active glucocorticoids.

Low dose of tocotrienols protects osteoblasts against oxidative stress.

AIMS: Vitamin E is an antioxidant that may protect bone against oxidative stress-induced osteoporosis. This in vitro study was conducted to determine the protective effects of a-tocopherol and γ-tocotrienol on osteoblasts, the bone forming cells, against oxidative stress. MATERIALS AND METHODS: Toxicity tests were carried out on hydrogen peroxide (H(2)O(2)), a-tocopherol and γ-tocotrienol and their inhibitory concentration 50 (IC(50)) on osteoblasts were determined if any. Osteoblast cultures were then pretreated with different concentrations of a-tocopherol or γ-tocotrienol for 24 hours before incubated with the IC50 of H(2)O(2) for 2 hours. Cell viability was determined by using MTS assay to compare the protective effects of both vitamin E on osteoblast exposed to H(2)O(2). RESULTS: The IC(50) after 2 hours and 24 hours incubation time for H(2)O(2) were 490 µM and 280 µM respectively. γ-Tocotrienol was found to be toxic to osteoblasts with the IC(50) of 290 µM after 24 hours incubation time while a-tocopherol was not toxic to osteoblasts at any doses. However, γ-tocotrienol was able to protect osteoblasts from H(2)O(2) toxicity at low concentration (1 µM), whereras a-tocopherol was not able to offer protection against H2O2 toxicity. CONCLUSIONS: γ-tocotrienol was found to be toxic to osteoblasts at high concentrations but at much lower concentration, it has better antioxidant activity than a-tocopherol to protect osteoblasts from oxidative stress.

Effects of vitamin E on receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) in rats treated with nicotine.

Vitamin E is found to reverse the effects of nicotine on bone and this study aimed to determine its mechanism. Male Sprague Dawley rats were divided into four groups and treated for 3 months: Group 1 was the control group (RC). Groups 2 (N), 3 (N+TT) and 4 (N+ATF) received nicotine 7 mg/kg throughout the treatment period. In addition, groups 3 and 4 received tocotrienol 60 mg/kg and alpha-tocopherol 60 mg/kg respectively during months 2 and 3. Parameters measured were serum osteoprotegerin (OPG), serum receptor activator of nuclear factor kappa B ligand (RANKL), femoral and lumbar bone calcium content and body weight. Nicotine did not affect OPG or RANKL levels but reduced bone calcium content suggesting the calcium loss is not due to increase osteoclastogenesis. OPG was increased in N+ATF while RANKL was slightly increased in N+TT. Both vitamin E supplements restored bone calcium loss induced by nicotine. Nicotine impaired weight gain in all treatment groups starting week 4 however, N+TT group was comparable to RC from week 6 onwards. Bone protective effects of ATF, but not TT, may be partly due to inhibition of osteoclastogenesis.

Effects of vitamin E supplementation on bone metabolism in nicotine-treated rats.

INTRODUCTION: Nicotine has been shown to exert negative effects on bone. This study determined whether vitamin E supplementation is able to repair the nicotine-induced adverse effects in bone. METHODS: 24 male rats were divided into three groups. The fi rst group was the baseline control and killed untreated at the beginning of the study. Groups 2 and 3 received nicotine at 7 mg per kg for three months but during the second and third months, group 2 was supplemented with alpha-tocopherol (N+ATF) while group 3 was given palm tocotrienol mixture (N+TT). Serum interleukin-1 (IL-1), serum interleukin-6 (IL-6), serum osteocalcin, urine deoxypyridinoline (DPD) and bone calcium content were measured. RESULTS: Palm tocotrienol mixture was able to prevent the increment of IL-1 and IL- 6 due to nicotine treatment. No changes were seen in the osteocalcin levels, but the N+ATF group had lower urine DPD levels after treatment. However, bone-remodelling index revealed no significant changes. No significant differences were seen in the femoral bone calcium content results, although the fourth lumbar bone calcium content was reduced in both groups with 66.5 percent reduction in the N+ATF group and 59.6 percent reduction in the N+TT group. CONCLUSION: Palm tocotrienol mixture was better than alpha-tocopherol in reversing the effects of nicotine on IL-1 and IL-6. Both forms of vitamin E were not able to restore the nicotine-induced bone calcium loss, but the N+ATF group suffered a greater loss. Tocotrienol seemed to be superior to alpha-tocopherol in combating against the adverse effect of nicotine.

The effects of repeatedly heated frying oil and high cholesterol diet on the bone in ovariectomised rats.

The use of repeatedly heated frying oils and intake of high cholesterol diet have been linked to bone damage. The aim of this study is to determine the combined effects of taking repeatedly heated frying oils (palm or soy oil) and high cholesterol diet on the dynamic histomorphometric parameters of bone. Ovariectomised rats were used as animal model of post-menopausal osteoporosis. After six months of treatment, Double-labeled Surface (dLS/BS), Mineralising surface (MS/BS) and Bone Formation Rate (BFR/BS) of ovariectomised rats (OvxC) were significantly reduced compared to the normal control group. Additions of fresh or once-heated palm or soy oil into high cholesterol diet seem to have improved the dynamic parameters towards the normal control values. However, when these oils were repeatedly heated, the protective effects were lost and the dynamic parameters except MS/BS dropped back towards the ovariectomised-control values.

The effects of repeatedly heated frying oil and high cholesterol diet on the bone in ovariectomised rats

The use of repeatedly heated frying oils and intake of high cholesterol diet have been linked to bone damage. The aim of this study is to determine the combined effects of taking repeatedly heated frying oils (palm or soy oil) and high cholesterol diet on the dynamic histomorphometric parameters of bone. Ovariectomised rats were used as animal model of post-menopausal osteoporosis. After six months of treatment, Double-labeled Surface (dLS/BS), Mineralising surface (MS/BS) and Bone Formation Rate (BFR/BS) of ovariectomised rats (OvxC) were significantly reduced compared to the normal control group. Additions of fresh or once-heated palm or soy oil into high cholesterol diet seem to have improved the dynamic parameters towards the normal control values. However, when these oils were repeatedly heated, the protective effects were lost and the dynamic parameters except MS/BS dropped back towards the ovariectomised-control values.