The use of stable and radioactive sterol tracers as a tool to investigate cholesterol degradation to bile acids in humans in vivo

3-Hexanoyl-7-nitrobenz-2-oxa-1,3-diazol-4-yl-cholesterol (3-NBD-cholesterol) is a versatile cholesterol tracer

Membrane cholesterol influences a large number of cellular processes and the dynamics of cholesterol exchange between membranes is an area of active study. However, analogs containing a fluorophore on the isooctyl side chain of cholesterol are commonly used without regard for the potential impact of the fluorophore on membrane structure. We investigated the capacity of 3-hexanoyl-7-nitrobenz-2-oxa-1,3-diazol-4-yl-cholesterol (3-NBD-cholesterol), which is labelled at the C3 position, to trace cholesterol dynamics in cellular systems. Transfer of 3-NBD-cholesterol from erythrocytes to lipoproteins replicated known properties of cholesterol. Labelled cells were also readily detected by flow-cytometry and microscopy. Using flow-cytometry it was also possible to follow the uptake of 3-NBD-cholesterol labelled extracellular vesicles. These data indicate that 3-NBD-cholesterol is a versatile cholesterol tracer in different cell models and extracellular vesicles.

Hypolipidaemic Effects of High Resistant Starch Sago and Red Bean Flour- based Analog Rice on Diabetic Rats

INTRODUCTION

Sago analog rice had known as an example of food with high resistant starch. Recent research shows that sago analog rice and red bean flour also had a low glycemic index (GI). However, Identification of hypolipidaemic mechanism based on the nutrigenomic analysis remains unknown.

AIM

This study aims to determine the effects of hypolipidaemic in diabetic rats with analog rice treatment.

MATERIAL AND METHODS

Thirty-five male Wistar rats were divided into 5 groups with different food treatment, such as standard dietary food (STD) group, and four groups of diabetic rats with standard dietary food (STDD), mentik wangi rice diet (MWRD), sago analog rice (SARD) and sago analog rice with 10% red bean flour (SARKBD). Lipid profile was observed every week for a month. Measurement of insulin and blood glucose was performed twice at the beginning and end of treatment. Atherogenic index (AI) was also investigated. Then, the pancreas was collected for histological analysis.

RESULTS

SARD group showed the highest effect of decreasing the total cholesterol (47.74%) which followed by SARKBD (34.62%). The triglyceride level in SARD group was also significantly decreased (31.14%), followed by SARKBD (19.32%). However, the HDL increase in SARD (48.66%), followed by SARKBD (36.00%). The LDL level in SARD and SARKBD group were significantly decreased, respectively 32.89% and 22.19%. SARD atherogenic index levels lower than SARKBD; 1.00 and 2.06.

CONCLUSION

The improvement of insulin resistance by SARD and SARKBD were generated by role of resistant starch through the mechanism of bile acid binding, insulin sensitivity escalation and SCFA effect.

A Potential of Coleus Tuberosus Crackers Rich in Resistant Starch Type 3 Improves Glucose and Lipid Profile of Alloxan –Induced Diabetic Mice

This study aims to determine the consumption effect of Coleus tuberosus flour and crackers rich in resistant starch type 3 to glucose and lipids profiles in diabetic mice. The study was conducted with four treatments (normal mice with AIN 93 diet, diabetic mice with AIN 93 diet, diabetic mice with Coleus tuberosus flour diet, diabetic mice with coleus tuberosus crackers rich in resistant starch type 3). The analysis of blood glucose levels and lipids profile were determined using an enzymatic colorimetric method with a commercial kit. The results showed that the consumption of Coleus tuberosus flour and crackers rich in resistant starch type 3 can improve glucose and lipids profile (total cholesterol, triglycerides, low-density lipoprotein, high-density lipoprotein) in alloxan-induced diabetic mice. The atherogenic index was smaller on the diet treatment of Coleus tuberosus flour rich in resistant starch type 3 and Coleus tuberosus crackers rich in resistant starch type 3 compared to the AIN 93 feed.This study shows that the raw material (Coleus tuberosus flour rich in resistant starch type 3) and Coleus tuberosus crackers that are rich in resistant starch type 3 can potentially be consumed as a functional food to improve glucose and lipid profiles in diabetes mellitus condition.

Rate of steroid double-bond reduction catalysed by the human steroid 5β-reductase (AKR1D1) is sensitive to steroid structure: implications for steroid metabolism and bile acid synthesis

Human AKR1D1 (steroid 5β-reductase/aldo-keto reductase 1D1) catalyses the stereospecific reduction of double bonds in Δ4-3-oxosteroids, a unique reaction that introduces a 90° bend at the A/B ring fusion to yield 5β-dihydrosteroids. AKR1D1 is the only enzyme capable of steroid 5β-reduction in humans and plays critical physiological roles. In steroid hormone metabolism, AKR1D1 serves mainly to inactivate the major classes of steroid hormones. AKR1D1 also catalyses key steps of the biosynthetic pathway of bile acids, which regulate lipid emulsification and cholesterol homoeostasis. Interestingly, AKR1D1 displayed a 20-fold variation in the kcat values, with steroid hormone substrates (e.g. aldosterone, testosterone and cortisone) having significantly higher kcat values than steroids with longer side chains (e.g. 7α-hydroxycholestenone, a bile acid precursor). Transient kinetic analysis revealed striking variations up to two orders of magnitude in the rate of the chemistry step (kchem), which resulted in different rate determining steps for the fast and slow substrates. By contrast, similar Kd values were observed for representative fast and slow substrates, suggesting similar rates of release for different steroid products. The release of NADP+ was shown to control the overall turnover for fast substrates, but not for slow substrates. Despite having high kchem values with steroid hormones, the kinetic control of AKR1D1 is consistent with the enzyme catalysing the slowest step in the catabolic sequence of steroid hormone transformation in the liver. The inherent slowness of the conversion of the bile acid precursor by AKR1D1 is also indicative of a regulatory role in bile acid synthesis.