Introduction

Roselle has a  long history of application. In early studies, Roselle mainly focuses on the effects of muscle relaxing, anti-oxidation, anti-bacteria, and anti-parasitic. However, in recent studies, it also has the effects on protecting the function of the kidney, reducing blood lipid...

Pharmacological effects

The pharmacological effect of roselle has been studied extensively by scholars at home and abroad, and it has been confirmed that it has a variety of biological activities such as antioxidant, diuresis, anti-tumor, lowering blood lipid, anti-diabetes and complications, lowering blood pressure, etc.The research on pharmacological activity in recent ten years focuses on several aspects.

Lowering blood lipid

Studies have shown that roselle extract has lipid-lowering activity and has a preventive effect on hyperlipidemia, vascular diseases and atherosclerosis.The water and alcohol extracts of dried calyx and leaf were significantly reduced

The concentration of low density lipoprotein cholesterol (LDL-C), triglyceride (TAG) and total cholesterol (TC) in serum inhibits lipid peroxidation, foam cell formation, smooth muscle cell migration and calcification in blood vessels.Less commonly, the extract also reduced very low density lipoprotein cholesterol (VLDL-C) and increased serum high density lipoprotein cholesterol (HDL-C) concentration.The possible mechanisms are inhibition of triacylglycerol synthesis, inhibition of LDL-C oxidation, increase of △9, △6 fatty acid desaturase activity. Anthocyanins and protocatechuic acid may be the active components that play this role.

Anti-diabetes and complications

Roselle extract has a similar effect to Ligliptin (DPP-4 inhibitor) and significantly improves insulin resistance, epithelial-mesenchymal transition (EMT) and hyperinsulinemia. It has α -amylase inhibitor effect and significantly improves postprandial hyperglycemia.

In type II diabetic rats, roselle polyphenol extract (HPE) simultaneously reduced the levels of DPP-4, high glucose induced angiotensin II receptor-1 (AT-1), vimentin and fibronectin, and reversed the in vivo compensation of glucagon-like peptide 1 receptor (GLP-1R).HPE improves insulin sensitivity by downregulating DPP-4 and downstream signaling and reducing AT-1-mediated renal epithelial mesenchymal transition (EMT).

Roselle polyphenol extract showed a protective effect on nephropathy induced by streptozotocin (STREptozotocin) in type I diabetes mellitus, and significantly improved renal weight reduction and edema symptoms of near circumducted tubules, which may be related to increased catalase activity and regulation of Akt/Bad / 14-3-3 γ signaling pathway.These results indicate that roselle is an adjuvant that can prevent diabetic nephropathy.

Antioxidant

Early studies have shown that roselle extract has a strong antioxidant effect, improving cell oxidative damage induced by tert-butyl hydroperoxides (T-BHP), increasing the activities of superoxide dismutase and catalase, and reducing the concentration of malondialdehyde.The mechanism may be related to the inhibition of reactive oxygen species, free radicals and xanthine oxidase activities.This antioxidant activity has been observed in water and alcohol extracts of flowers, seeds and leaves.

The water extract of Roselle (100 ~ 800 mg· kg-1) could significantly improve the hepatitis model induced by the toxins in vivo (tert-butylhydroperoxide, lipopolysaccharide azathioprine, carbon tetracloride).Effectively reduce the concentrations of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in blood.This effect may be due to its strong antioxidant activity, blocking the oxidative stress response and increasing the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and D-aminolevulinic acid dehydrase (D-ala-D).Decreases the expression of Bax and tBid proteins in liver cells.

Diuresis and drainage of stones

In vivo experiments, it was observed that roselle extract had the effect of removing stones. Woottisin et al. adopted Wistar rats and administered roselle extract daily (oral dose was 3.5 mg· kg-1). The results showed that the deposition of oxalate and calcium salt in the kidney was significantly reduced.A few stones were detected in the urine.Laikangbam et al. also found that water extracts of roselle (250, 500, 750 mg· kg-1) could effectively prevent the formation of renal stones in male rats.

Anti-tumor

Roselle is rich in polyphenols such as protocatechuic acid, gallic acid, chlorogenic acid, and epicatechin gallate.A number of studies have shown that it can inhibit the malignant proliferation of prostate cancer cells, promyelocytic leukemia cells, melanoma cells and other cells.The mechanism of action may be through inhibition of bcl-2 gene ____expression (B lymphocytuma-2 gene) and tumor suppressor gene (RB gene) phosphorylation and deactivation, Mediated endogenous (Bax/cytochrome C-mediated Caspase 9) and exogenous (Fas-mediated Caspase 8 / T-bid) pathways exert anti-apoptotic effects.Or by adding autophagy related genes (ATG5), Beclin1, and light chain 3-II (LC3-II) tables.