Evaluation of the antiosteoporotic potential of Tinospora cordifolia in female rats

Abstract

The available courses of therapy to osteoporosis in menopausal women are limited by several side effects generated. A need therefore arises to explore herbal alternatives that are effective and safe.

Objective

Present animal studies were conducted to investigate the potential of Tinospora cordifolia (TC) ethanolic stem extract as an antiosteoporotic agent.

Methods

Three-month-old female Sprague–Dawley rats were either ovariectomized (ovx) or sham operated and treated with vehicle (benzyl benzoate:castor oil; 1:4), E₂ (1 μg/day) or TC (10, 50, 100 mg/kg b.wt) subcutaneously for 4 weeks. At the end of experiment bone mineral density of tibiae was measured by quantitative computer tomography. Serum was analyzed for the activity of alkaline phosphatase and levels of osteocalcin, cross-laps and lipids. Uterus and mammary gland were processed for histological studies.

Results

Ovx rats treated with TC (10 mg/kg b.wt) showed an osteoprotective effect as the bone loss in tibiae was slower than ovx controls. Serum osteocalcin and cross-laps levels were significantly reduced. All the above effects of TC were much milder than those produced by E₂. Alkaline phosphatase activity was higher in TC treatment groups. Total cholesterol and LDL levels remained unaltered but HDL levels were significantly lowered with TC (50 mg/kg b.wt) treatment. Uterus and mammary gland showed no signs of proliferation after treatment with TC extract.

Conclusion

TC extract showed estrogen like effects in bone but not in reproductive organs like uterus and mammary gland. Thus, this study demonstrates that extract of T. cordifolia has the potential for being used as antiosteoporotic agent.

Introduction

Bone is a metabolically active tissue that undergoes constant remodeling throughout life by cells known as osteoblasts and osteoclasts. This modeling enables the skeletal system to periodically grow and to repair its structural damages [1]. Disruptions in this dynamic system proceed towards the condition known as osteoporosis, which is defined by WHO as “A progressive skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture” [2]. Factors that regulate the rate of bone loss are heredity, dietary calcium intake, vitamin D levels, physical inactivity, low body weight, smoking, alcohol intake and hormones, in particular sex steroids. Both sexes show initiation of bone loss between 35 and 40 years but in females, advancing age and postmenopausal decline of estradiol (E₂) accelerates the loss and incline them towards increased risk of osteoporosis [3]. One of the factors responsible for the progression of bone loss due to declined levels of gonadal hormones is inflammation [4]. Bone and bone marrow cells produce cytokines which act locally to regulate osteoclasts function. Normally, their production is regulated by estrogen and cytokines mediate much of the steroid action on the skeleton. Therefore, hormonal depletion during menopause affect cytokine levels causing accelerated bone loss [5]. Treatments available increase bone density either by inhibiting resorption (e.g. bisphosphonates, raloxifene, calcitonin, hormone replacement therapy and vitamin D), by increasing formation (e.g. Terparatide) or by acting both ways (e.g. strontium ranelate). All these treatments are efficacious in their own ways but associated problems like gastrointestinal disturbances, venous thromboembolism, flushing, vomiting, diarrhea, coronary events, strokes, endometrial hyperplasia, esophagitis and breast cancer make them less desirable among patients [6], [7]. Nowadays focus has been driven towards seeking alternative regimes like herbs which improves the bone imbalances without causing any side effects. In the past years plants like Cissus quandrangularis, Cimicifuga racemosa, Onobrychis ebenoides, Puerariae radix and many more have been reported beneficial for restoring the bone loss [8], [9], [10], [11] and search for new plants is going on. Tinospora cordifolia (Menispermaceae) has been used in ayurvedic preparations since ancient times. It is a deciduous climbing shrub indigenous to tropical Indian subcontinent [12]. The plant is commonly known as Guduchi, Giloya, which is a Hindu mythological term that refers to the heavenly elixir which has saved celestial beings from old age and kept them eternally young. In the Indian system of medicine, T. cordifolia has been known to promote longevity and increase the body's resistance against various diseases [13]. The plant stem is one of the main constituent of herbal preparations that are being used in general debility, dyspepsia, fever, and urinary diseases. It has been extensively reported as a general tonic, antispasmodic, anti-inflammatory, anti-arthritic, anti-allergic and anti-diabetic agent [14], [15], [16], [17]. The plant is also well known for its adaptogenic and immunomodulatory activity [18]. A plethora of organic molecules with diverse structures such as alkaloids, terpenoids, glycosides, sterols, lactones, and fatty acids have been reported from this herb [19], [20]. Inflammation is reported as one of the major causes of bone loss and profound use of this plant in preparation of several immunomodulatory and anti inflammatory medicines encouraged us to investigate the antiosteoporotic potential of T. cordifolia in ovariectomized rat model of osteoporosis.