In a recent study, researchers at Fudan University in Shanghai explored the medicinal properties of B. smithii. They isolated polysaccharides from the plant and tested their effects in mice with diabetic kidney injury. Diabetes can damage the kidneys, although this occurs slowly over many years. This metabolic disorder is the leading cause of kidney disease, which affects one out of four adults with Type 1 or Type 2 diabetes.
The researchers discussed the kidney-protective effects of B. smithii polysaccharides in an article published in the Chinese Journal of Natural Medicines.
The genus Bupleurum is a large genus of perennial herbs and woody shrubs that belong to the carrot (Apiaceae) family. According to botanical records, at least 42 of the more than 180 species that constitute this genus can be found in China, and most -- if not all of them -- can be used as natural medicines.
Over the years, investigations on the medicinal properties of Bupleurum plants have revealed that their roots are rich sources of bioactive components. These include coumarins, flavonoids, lignans, polysaccharides, saponins, sterols and essential oils. Bupleurum plant roots are commonly (and traditionally) used to regulate metabolism and to treat fever and pain caused by influenza and the common cold.
Extracts derived from Bupleurum plants are also used for medicinal purposes. Research suggests that these extracts can protect against or reduce the symptoms of various conditions, such as hepatitis, nephrotic syndrome and autoimmune diseases. According to a study published in PLoS ONE, the polysaccharides isolated from B. smithii have anti-inflammatory and antioxidant properties that can ameliorate diabetes and protect pancreatic and liver cells from oxidative and inflammatory damage.
In the present study, the researchers investigated the kidney-protective properties of B. smithii polysaccharides (BP) using mice with streptozotocin (STZ)-induced diabetes. They administered 30 or 60 mg/kg BP orally to the animals every day. (Related: The potential of tongxinluo for treating diabetic nephropathy.)
The researchers reported that the mice injected with STZ had impaired kidney function, kidney inflammation and fibrosis (scarring) -- all of which were clear signs of diabetic kidney disease. Treatment with BP, however, reduced the animals' serum creatinine levels and urinary albumin excretion rate, as well as attenuated the swelling of their kidneys. BP treatment also alleviated the pathological damage caused by STZ on the animals' kidneys.
In addition, the researchers found that BP inhibited the progression of kidney damage by reducing the expression of type IV collagen, fibronectin (FN) and a-smooth muscle actin, which are all proteins involved in the scarring process. Meanwhile, they associated the inhibition of kidney inflammation with reduced levels of tumor necrosis factor-a (TNF-a) and interleukin-6 (IL-6), two signaling proteins that help trigger inflammation in response to tissue damage or infections.
BP treatment also suppressed the over-expression of toll-like receptor 4 (TLR4) and high-mobility group box 1 (HMGB1), which are involved in chronic kidney disease, and decreased the activity of nuclear factor kappa B (NF-kB) -- a pivotal mediator of inflammatory responses -- in the kidneys of diabetic mice. These altogether suggest that B. smithii polysaccharides exert their protective effects against kidney injury by interfering with the HMGB1-TLR4 pathway and suppressing kidney inflammation and fibrosis.
Based on these findings, the researchers concluded that B. smithii polysaccharides can prevent kidney injury caused by diabetes.