Research On The Chemical Constituents Of The Flower Of Bombax Malabaricum And The Antidiabetic Effects Of The Active Part

Bombax malabaricum DC. Flower is the dry flower of the Bombax malabaricum DC., mainly grows in tropical and subtropical areas such as Southern China, India and Northern Australia. In China, the try flower of B. malabaricum has been used versatilely not only in medicinal treatment but also in herbal tea, B. malabaricum is widely used in folk medicine for the treatment of chronic inflammation, diarrhea, fever, dysentery and so on. Studies on its biological activity covered atioxidant, hepatoprotective, cardioprotective, anti-inflammatory, antimicrobial and so on, but the related constituents and pharmacological function has not been investigated. It was, thus, deemed of interest to isolate, characterize and identify constituents of the flower, to evaluate the potential bioactivities of the compounds, as well as to explore the antidiabetic effects of the active part of the flower related to the use of the plant in traditional medicine.In this work, chromatographic techniques and various spectroscopic methods were used for isolation and identification. And fifteen compounds (1-14) were isolated and purified from the flower of B. malabaricum They were identified as β-sitosterol (1), daucosterol (2), protocatechuic acid (3), mangiferin (4), tamarixin (5), isoquercetin (6), 2’-trans-O-coumaroylmangiferin (7), rutin (8), isovitexin (9), luteolin-6-C-glucoside(10), (N-(Z)-p-coumaroyltyrosine lla) (N-(E)-p-coumaroyltyrosine 11b)、, quercetin (12), aurantiamide (13), and scopoletin(14). Among these compounds,5,7,10,11, and 13 were reported for the first time in this plant genus.On the basis of chemical investigation, we developed an analytical method to simultaneously quantify 12 constituents in the flower, and UPLC-MS was used for the quantification of the constituents (3-13) in different part of the flower (whole flower, calyxs, petals, tamens) and four crude extract (methanol extraction, methanol phase,1:1 phase and aqueous phase). The study showed that 3,4,5 were the main constituents in the flower, and the contents were less concentrated in stamens than in petals and calyxs. In the four crude extracts,1:1 phase (the 1:1 eluted part from a DIAION conlumn) contained higher levels of flavonoidsr and the most abundant constituents were 3,4,5 and 7.The antioxidant and maltase inhibitory activities of 15 compounds and 4 cruds extracts were investigated. DPPH radical scavenging activity and protective effects on DNA scission were investigated respectively, and the results indicated that seven compounds and 1:1 phase showed strong antioxidant activities with EC50 on DPPH radical being less than 20 μg·mL-1, and these compounds also showed strong protective effects on peroxyl radical-induced DNA scission. Compound 3 and 12 exhibited inhibition on maltase with IC50 values of 51.5 and 38.24 μg·mL-1.We investigated the antidiabetic effects of the 1:1 phase and the hypoglycemic/hypolipidemic effects were evaluated by measuring blood glucose, lipid profile, oxidative stress and liver function. After treated for 3 weeks, typical symptom of diabetic rats, such as emaciation, polyphagia, polyuria and polydipsia were relieved at the dose of 200 mg·kg-1, the fasting blood glucose levels showed a significant decreasing (p<0.01); The glucose tolerance and insulin tolerance of the diabetic rats were improved, maintained glucose homeostasis of the organism and improved the insulin sensitivity; The 1:1 phase also showed capability to regulate lipid metabolism, Compared with the model group, the 200 mg/kg treated group demonstrated significantly decreased (P<0.01) serum total cholesterol (TC), total triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C) levels, and significantly increased (P<0.05) low-density lipoprotein cholesterol (LDL-C) level; The 200 mg/kg treated group also showed significantly reduced levels of AST (P<0.01) and ALT (P<0.01) as compared with the model group, indicated that the 1:1 phase may inhibit the liver damage induced by STZ; Superoxide dismutase (SOD) activity increased and malondialdehyde (MDA) level dereased in the 1:1 phase treated group, indicated that the ability of anti-oxidative was improved. These results suggest that the flower of Bombax malabaricum DC. is a potential candidate for the future development of anti-diabetes agent.The chemical constituents of the flower of B. malabaricum were investigated systemically, quality control were established, and pharmacodynamics basis were evaluated in this paper, which provide a scientific basis for the development and utilization of the plant in traditional medicine.