Journal of Bone and Mineral Metabolism

, Volume 27, Issue 5, pp 584–590

The effects of Acanthopanax senticosus extract on bone turnover and bone mineral density in Korean postmenopausal women

Authors

  • You-Cheol Hwang
    • Division of Endocrinology and Metabolism, Department of Medicine, Kyung Hee East-West Neo Medical CenterKyung Hee University School of Medicine
  • In-Kyung Jeong
    • Division of Endocrinology and Metabolism, Department of Medicine, Kyung Hee East-West Neo Medical CenterKyung Hee University School of Medicine
  • Kyu Jeung Ahn
    • Division of Endocrinology and Metabolism, Department of Medicine, Kyung Hee East-West Neo Medical CenterKyung Hee University School of Medicine
    • Division of Endocrinology and Metabolism, Department of Medicine, Kyung Hee East-West Neo Medical CenterKyung Hee University School of Medicine
Original Article

DOI: 10.1007/s00774-009-0093-3

Cite this article as:
Hwang, Y., Jeong, I., Ahn, K.J. et al. J Bone Miner Metab (2009) 27: 584. doi:10.1007/s00774-009-0093-3

Abstract

The purpose of this prospective randomized study was to investigate the effects of the extract of Acanthopanax senticosus (AS extract), a widely used oriental herb, on bone remodeling and bone mineral density in Korean postmenopausal women. A total of 81 postmenopausal women with osteopenia or osteoporosis, an age of less than 65 years, were enrolled in the study. Subjects were randomly assigned to two groups: (1) the control group (n = 40), calcium intake (500 mg per day), and (2) the treatment group (n = 41), calcium (500 mg per day) plus AS extract (3 g per day). After treatment with AS extract for 6 months, the AS extract group showed a significant increase in serum osteocalcin levels compared with the control group (P = 0.041). However, no significant changes in bone mineral density were observed by dual-energy X-ray absorptiometry (DXA). AS extract was generally well tolerated, and no differences were observed between the two groups in terms of adverse events. This study suggests that AS extract supplementation may have beneficial effects on bone remodeling in Korean postmenopausal women and that it has no significant adverse events.

Keywords

Acanthopanax senticosusPostmenopausal womanBone turnoverBone mineral density

Introduction

Osteoporosis is the most common metabolic bone disorder and an important health care issue in both Caucasians and Asians [1]. In the United States, approximately 8 million women and 2 million men have osteoporosis, and it has been estimated that more than 14 million people will be affected in 2020 [2]. The burden of osteoporosis for 2005 in the United States was estimated to be more than 2 million incident fractures, and the associated direct medical costs were estimated at $17 billion. However, it has been predicted that fractures and costs will be increased by more than 48% to more than 3 million fractures by 2025, which would increase the overall cost to $25.3 billion [3]. Similarly, in Korea the prevalence of osteoporosis has increased dramatically from 2.87 per 1,000 (Korean National Health and Nutrition Examination Survey (KNHANES) 1998) to 11.55 per 1,000 in the 2002 KNHANES survey, and the incidence of osteoporotic fractures of wrist, spine, and femur in subjects over 50 years of age has been reported to be 22.4, 26.3, and 20.8 per 10,000 persons, respectively [4].

Accumulating evidence suggests that natural products, such as herbal extracts and dietary supplements, have favorable effects on bone health [5, 6]. For example, turmeric root (Curcuma longa), which has long been used to treat inflammatory diseases, and its active constituents, curcuminoids, are known to have favorable effects on bone metabolism. Furthermore, it has been reported that curcumin (a mixture of curcuminoids) can prevent osteoclastogenesis and that is also has antiinflammatory and antioxidant effects [5].

Acanthopanax senticosus, also called Siberian ginseng, is a widely used oriental herb that has been reported to have immunomodulatory, hypoglycemic, antistress, antitumor, and antioxidant effects [713]. In addition, the stems of A. senticosus have been used clinically to treat allergic diseases in Korea. However, no investigation has been conducted on the effect of A. senticosus extract (AS extract) on bone health. Therefore, this study was conducted to investigate the effects of AS extract on biochemical markers of bone turnover and bone mineral density in Korean postmenopausal women.

Materials and methods

Plant materials and extraction

Acanthopanax senticosus leaves as supplied had a moisture content of less than 10% by weight and were air-dried at 60°C for 36 h. Leaves were then powdered and extracted in hot water. The supernatant obtained was filtered (Whatman No. 3; England), concentrated under vacuum, and freeze-dried for 72 h. This process produced 8.15 g (yield, 16.3%) brown powder.

Study subjects

The study subjects were recruited from among those who visited the Kyung Hee East-West Neo Medical Center in Seoul. Eligibility criteria were postmenopausal status, age less than 65 years, and dual-energy X-ray absorptiometry (DXA)-proven osteopenia or osteoporosis. We excluded subjects with any of the following: (1) previous medication likely to affect bone metabolism, such as hormone replacement, tamoxifen, vitamin D, steroids, or other antiresorptive agents within 2 months before the screening period (actually, no study subjects had been treated with antiresorptive agents including bisphosphonates 1 year before screening); (2) previous history of liver or kidney disease; (3) heavy alcohol consumption or cigarette smoking; or (4) malabsorption syndrome. The Ethics Committee and Institutional Review Board of Kyung Hee University approved the study procedures, and the study was conducted in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice. Written informed consent was obtained from all participants before enrolment.

Study design

This open-label, comparative study was 6 months in duration. During a month-long preliminary period before administration, subjects were assessed using a standardized food frequency questionnaire for relevant demographics, medical history, and dietary pattern, which included calculation of daily calcium, phosphorus, and protein intake. In addition, a physical examination was performed and bone turnover markers and bone mineral densities were measured. After the preliminary period, 81 postmenopausal women were enrolled and randomly assigned to two groups: (1) the control group (n = 40), calcium intake 500 mg per day, and (2) the treatment group (n = 41), calcium intake 500 mg per day plus AS extract at 3 g per day. Safety issues were assessed at 1 and 3 months after the study commenced, and AS extract efficacy was determined after 6 months. During the 6-month treatment period, 13 patients dropped out. Thus, 68 patients (33 patients in the AS extract group and 35 patients in the control group) who completed 6 months of treatment were included in the analysis.

BMD measurements

The bone mineral density (BMD) in lumbar spines (L1–L4), in left total proximal femur, and in left femoral neck were measured by DXA using a Lunar Prodigy unit (GE Healthcare, Madison, WI, USA) at baseline and after 6 months of treatment. Least significant change (LSC) was defined as DXA precision error multiplied by 2.77 (95% confidence interval) [14], and LSC values were 3.60, 4.43, and 3.04% for lumbar spine, total proximal femur, and femoral neck, respectively. To eliminate interoperator differences, the same operator performed the measurements in all subjects, and the operator was blinded to the allocation of the subjects.

Biochemical measurements

Serum samples were obtained before 9:00 AM after an overnight fast and were immediately processed and kept frozen at −20°C until assayed. Serum osteocalcin levels (a marker of bone formation) were measured using immunoradiometric assay kits (Osteo-RIACT; Cis Bio International, Yvette Cedex, France). Serum C-terminal telopeptide of type 1 collagen (CTx) levels (a marker of bone resorption) were measured using an electrochemiluminescence immunoassay method (Roche Diagnostic, Mannheim, Germany). Serum matrix metalloproteinase-10 (MMP-10), macrophage inflammatory protein-1α (MIP-1α), and interleukin-8 (IL-8) levels were determined using commercial enzyme-linked immunosorbent assay (ELISA) kits (Quantikine; R&D Systems, Minneapolis, MN, USA).

Statistical analysis

Analysis was performed using SPSS version 13.0 (SPSS, Chicago, IL, USA). The unpaired t test, the χ2 test, and analysis of covariance (ANCOVA) test were used to compare intergroup differences, and the paired t test was used to compare pre- to posttreatment differences. Partial and Pearson’s correlation coefficients were used to determine the presence of correlations between variables. P values less than 0.05 were considered statistically significant.

Results

Table 1 lists the baseline characteristics and biochemical parameters of the study subjects. No significant differences were observed between the treatment and control group with respect to age, duration of menopause, body mass index, previous fracture history, family history of fracture, and variables related to nutritional status (i.e., daily calcium and phosphorus intake and 25(OH)D). Other markers likely to increase under inflammatory conditions, i.e., WBC, homocysteine, high-sensitivity C-reactive protein (hsCRP), and other cytokines, such as MMP-10, MIP-1α, and IL-8, also did not differ in the two groups. At study commencement (baseline), bone mineral density was measured in lumbar spine, left total proximal femur, and left femoral neck, but no intergroup differences were noted. However, bone turnover markers, i.e., serum osteocalcin (P = 0.013) and CTx (P < 0.0001) levels, were significantly higher in the treatment group.
Table 1

Baseline characteristics of the study subjects

 

Acanthopanax senticosus group (n = 33)

Control group (n = 35)

P value

Age (years)

56.2 ± 4.1

56.4 ± 3.9

NS

Age of menopause (years)

49.6 ± 3.5

48.6 ± 3.6

NS

Duration of menopause (years)

6.5 ± 4.6

7.7 ± 4.6

NS

No. of previous history of fracture (%)

6 (18.1)

8 (22.8)

NS

No. of family history of fracture (%)

9 (27.2)

4 (11.4)

NS

Body mass index (kg/m2)

23.8 ± 2.5

23.6 ± 2.1

NS

Calcium intake (mg/day)

597.0 ± 235.0

606.6 ± 195.2

NS

Phosphorus intake (mg/day)

1013.4 ± 286.3

980.4 ± 229.4

NS

Protein intake (g/day)

64.7 ± 17.9

64.5 ± 16.2

NS

24-h urine calcium excretion (mmol/day)

6.62 ± 3.03

5.81 ± 2.57

NS

25(OH)D (nmol/l)

83.3 ± 27.5

79.0 ± 25.0

NS

WBC (×103/μl)

5.3 ± 1.0

5.3 ± 1.2

NS

hsCRP (mg/l)

1.06 ± 0.82

0.99 ± 1.09

NS

Homocysteine (μmol/l)

5.48 ± 1.14

6.08 ± 2.75

NS

MMP-10 (pg/ml)

683.7 ± 401.5

719.5 ± 282.3

NS

MIP-1α (pg/ml)

96.2 ± 12.0

92.8 ± 17.9

NS

IL-8 (pg/ml)

62.8 ± 9.8

62.4 ± 10.7

NS

Osteocalcin (μg/l)

16.43 ± 4.94

13.71 ± 3.83

0.013

CTx (ng/l)

509.9 ± 155.1

370.4 ± 122.2

<0.0001

Lumbar spine BMD (g/cm2)

0.875 ± 0.074

0.901 ± 0.091

NS

Total proximal femur BMD (g/cm2)

0.866 ± 0.090

0.884 ± 0.078

NS

Femoral neck BMD (g/cm2)

0.769 ± 0.077

0.790 ± 0.080

NS

WBC white blood cells, hsCRP high-sensitivity C-reactive protein, MMP matrix metalloproteinase, MIP macrophage inflammatory protein, IL interleukin, CTx serum C-terminal telopeptide of type 1 collagen, BMD bone mineral density

Data are expressed as means ± SD for continuous variables and numbers (%) for patients

Correlations between inflammatory markers and bone turnover markers or bone mineral densities were evaluated at baseline. Summarizing, neither osteocalcin nor CTx levels were found to be significantly correlated with inflammatory marker or cytokine levels. Instead, total lumbar spine BMD was found to be significantly and positively correlated with MMP-10 (P = 0.022) and homocysteine (P = 0.018) levels (Table 2).
Table 2

Correlation coefficients between inflammatory parameters and bone turnover markers or bone mineral densities at baseline

 

BMD, lumbar spine

BMD, total proximal femur

BMD, femoral neck

Osteocalcin

CTx

MMP-10

0.260*

0.065

0.039

−0.022

−0.076

IL-8

0.025

0.006

0.072

−0.207

−0.193

MIP-1α

0.025

−0.044

0.005

0.072

0.181

WBC

0.039

0.162

0.018

−0.054

−0.043

hsCRP

0.072

0.069

−0.130

0.025

0.007

Homocysteine

0.288*

0.074

0.003

0.015

0.045

Adjusted for age, body mass index (BMI), and duration of menopause

P < 0.05

After treatment with AS extract for 6 months, no group differences were observed in terms of number of patients who showed change in BMD by more than LSC (Table 3). However, osteocalcin levels were significantly higher (P < 0.001) and CTx levels were significantly lower (P = 0.048) in the AS extract group after 6 months of treatment than at baseline. Moreover, despite controlling for baseline difference, osteocalcin levels in the two groups were significantly different after 6 months of treatment with AS extract (P = 0.041). However, no group differences in CTX levels were observed (Table 4).
Table 3

Changes in bone mineral densities by more than least significant change (LSC) as a result of treatment

 

A. senticosus group (n = 33)

Control group (n = 35)

Decrease

No change

Increase

Decrease

No change

Increase

Lumbar spine

3 (9.1)

22 (66.7)

8 (24.2)

2 (5.7)

29 (82.9)

4 (11.4)

Total proximal femur

1 (3.0)

32 (97.0)

0

0

34 (97.1)

1 (2.9)

Femoral neck

9 (27.3)

20 (60.6)

4 (12.1)

11 (31.4)

15 (42.9)

9 (25.7)

Data shown are numbers of patients (%)

Table 4

Changes in bone turnover markers resulting from treatment

 

A. senticosus group (n = 33)

Control group (n = 35)

Baseline

6 months

Baseline

6 months

Osteocalcin (μg/l)

16.43 ± 4.94

20.26 ± 6.76*

13.71 ± 3.83

14.62 ± 7.10**

CTx (ng/l)

509.9 ± 155.1

468.1 ± 165.8*

370.4 ± 122.2

351.5 ± 114.5

Data are means ± SE

P < 0.05 from baseline; ** P < 0.05 for difference caused by treatment

In addition, we investigated whether baseline clinical and inflammatory parameters were significantly correlated with bone turnover markers changes, and we found that lower baseline serum MMP-10 levels were significantly correlated with increases in serum osteocalcin levels by treatment (Table 5).
Table 5

Correlation coefficients between baseline clinical and inflammatory parameters and changes in bone turnover markers in Acanthopanax senticosus extract (AS extract) group

 

Percent Δ of osteocalcin

Percent Δ of CTx

γ

P value

γ

P value

Percent Δ osteocalcin

0.341

0.052

Percent Δ CTx

0.341

0.052

Age (years)

0.187

NS

0.229

NS

Age of menopause (years)

−0.082

NS

−0.124

NS

Duration of menopause (years)

0.227

NS

0.297

NS

Body mass index (kg/m2)

−0.138

NS

0.064

NS

WBC (×103/μl)

−0.020

NS

−0.183

NS

hsCRP (mg/l)

0.036

NS

−0.255

NS

Homocysteine (μmol/l)

−0.245

NS

0.011

NS

MMP-10 (pg/ml)

−0.348

0.048

−0.200

NS

MIP-1α (pg/ml)

−0.338

0.054

−0.203

NS

IL-8 (pg/ml)

0.254

NS

0.006

NS

No significant difference was observed between the two groups in terms of adverse events. The most common adverse event in both groups was gastrointestinal discomfort (indigestion or constipation), but incidences were not significantly different in the two groups [2 of 40 patients (5%) in the control group and 8 of 41 patients (19.5%) in the treatment group]. Furthermore, in terms of laboratory test findings, no significant intergroup differences were found for liver aminotransferases, creatinine, total cholesterol, or fasting plasma glucose levels (Table 6).
Table 6

Adverse events

 

A. senticosus group (n = 41)

Control group

(n = 40)

Any adverse event

9 (21.9)

4 (10)

Discontinuation of medication because of adverse event

4 (9.7)

3 (7.5)

Adverse events

 Gastrointestinal discomfort

8 (19.5)

2 (5.0)

 Arthralgia

1 (2.4)

1 (2.5)

 Urticaria

0

1 (2.5)

Laboratory abnormalitiesa

 Any liver aminotransferase > 1.5 × UNL

0

0

 Creatinine > UNL

0

0

 Δ Total cholesterol (mg/dl)

−2.36 ± 4.66

5.20 ± 3.70

 Δ Fasting plasma glucose (mg/dl)

2.33 ± 1.68

−0.06 ± 1.00

Data are expressed as means ± SE for continuous variables and as numbers for patients (%)

UNL upper normal limit

aData were available for 33 patients in the AS extract group and for 35 patients in control group

Discussion

In Asia, although A. senticosus has been widely used as an “adaptogen” to relieve stress, little is known of its active constituents in terms of their biological activities and mode of action. Recently, Davydov et al. [12] reported that A. senticosus contains various compounds such as acanthosides, eleutherosides, senticoside, triterpenic saponin, flavones, vitamins, and minerals, which are related to the diverse biological activities of A. senticosus such as its immunomodulatory, hypoglycemic, antistress, antitumor, and antioxidant effects. Lin et al. [8, 15] also suggested that A. senticosus inhibits nitric oxide production and iNOS gene expression in mouse peritoneal macrophages by inhibiting intracellular peroxide production, which has been implicated in the activation of NF-κB, and thus this inhibition may be partly responsible for the antiinflammatory effect of A. senticosus.

The present study showed that 6 months of treatment with AS extract may have a favorable effect on bone remodeling in Korean postmenopausal women with reduced bone mineral density, and it also showed that the herbal extract has no serious adverse events. More specifically, the AS extract significantly increased the level of the bone formation marker serum osteocalcin (23.3%) and decreased the level of the bone resorption marker serum CTx (8.2%). Rosen et al. [16, 17] suggested there is spontaneous long-term variability in biochemical markers even when no interventions are made; therefore, to demonstrate efficacy of the intervention, observed changes must systemically exceed the changes likely to occur spontaneously. In this regard, it is necessary to change more than the minimum significant changes of a marker, which was defined as 2.8 times (×2.8) the mean long-term intraindividual coefficient of variation (CV) . In this study, minimum significant changes for serum osteocalcin and CTx levels were 7.8 and 15.4%, respectively, and therefore it can be confidently stated that the observed change of osteocalcin (23.3%) was really the result of treatment effect. However, AS extract treatment did not significantly affect bone mineral density at any site, which may have been the result of the short treatment duration.

Although we cannot provide an exact mechanism for the favorable effects of AS extract on bone metabolism, we offer the following. First, it appears that AS extract mainly affects osteoblast activity toward a greater bone mass, i.e., by increasing serum levels of osteocalcin. Second, it was reported that A. senticosus contains various flavonoids such as quercetin, quercitrin, rutin, and hyperin [18], and possibly these compounds exert beneficial effects on bone health. Wattel et al. [19] demonstrated that quercetin, a flavonoid constituent of the leaves of A. senticosus, is a potent inhibitor of osteoclastic differentiation, via a mechanism involving NF-κB and AP-1. In addition, another group reported quercetin has a stimulatory effect on osteoblastic activity through the extracellular signal-regulated kinase (ERK) and estrogen receptor pathway [20].

It has been demonstrated that oxidative stress is a fundamental pathogenetic mechanism of skeletal involution. Almeida et al. [21] showed that bone strength and mass progressively decrease with age and that these changes are associated with a reduced rate of remodeling and increased osteoblast and osteocyte apoptosis in C57BL/6J mice. These changes are also linked with increased oxidative stress levels and decreased glutathione reductase activity. In one cross-sectional study, dietary and endogenous antioxidants (plasma vitamins C, E, and A), uric acid, superoxide dismutase, erythrocytes, and glutathione peroxidase activity were consistently lower in osteoporotic subjects than in normal controls [22]. Furthermore, it has been reported that inflammatory makers, such as plasma homocysteine levels, are significantly associated with reduced bone mineral density, high levels markers of bone turnover, and an increased fracture risk [2325]. However, our results reveal no correlations between baseline osteocalcin or CTx levels and inflammatory markers such as WBC, hsCRP, and homocysteine levels. Furthermore, lower baseline value of inflammatory markers, such as MMP-10 and MIP-1α, were found to be significantly correlated with greater osteocalcin level increases during the 6-month treatment period. These findings suggest that A. senticosus affects bone metabolism not by reducing inflammation or reactive oxygen species (ROS) levels, but by some other mechanism, such as by promoting osteoblastogenesis in bone.

MIP-1α is a member of the β chemokine subfamily (also called the CC chemokine subfamily), and MIP-1α has recently been suggested to be an osteoclast-activating factor in multiple myeloma-induced bone disease [26]. On the other hand, MMP-10 is a family of endopeptidases that degrade the extracellular matrix and basement membrane, and it has been reported that MMP-10 is strongly expressed in osteoclasts [27]. However, in the present study, we did not find any associations between MIP-1α or MMP-10 and CTx level at baseline. Furthermore, these novel bone resorption markers were not found to be correlated with inflammatory markers (data not shown) or bone mineral densities.

Our present study has some limitations. First, although we suggested that AS extract has favorable effects on bone health, no active component of AS extract directly related to bone remodeling was identified. Second, despite the random allocation, the baseline levels of osteocalcin and CTx were significantly higher in the AS extract group; therefore, although we controlled for these baseline differences via the statistical tool ANCOVA, it can still act as a confounding factor. Third, although it may be partly because of the short-term treatment, no group differences in bone mineral density of lumbar spine, left total proximal femur, and left femoral neck were observed.

In this study, the AS extract was generally well tolerated and appeared to have a good safety profile; i.e., no intergroup differences were noticed with respect to liver function tests or serum creatinine levels. The most common adverse effect was gastrointestinal discomfort, which may have been in part caused by the calcium supplementation administered. We conclude that supplementation with AS extract may have beneficial effects on bone remodeling in Korean postmenopausal women, and that it appears to have no significant adverse effect. A long-term study is required to confirm the effects of AS extract on bone mineral density, and additional studies are required to isolate active compounds and clarify the mechanism by which AS extract influences bone metabolism.

Acknowledgment

This work was supported by a grant from the Kyung Hee University in 2006 (KHU-20060489).

Copyright information

© The Japanese Society for Bone and Mineral Research and Springer 2009