beta-Sitosterol

1. Introduction of Beta-sitosterol
The Beta-sitosterol, with the CAS registry number 83-46-5, is a kind of white powder with no odour. It is widely distributed in the plant kingdom and found in Nigella sativa, pecans, Serenoa repens (saw palmetto), avocados, Cucurbita pepo (pumpkin seed), Pygeum africanum, cashew fruit. Beta-sitosterol is insoluble in water while soluble in chloroform and carbon disulfide. As to its usage, it is widely applied in many ways. Beta-sitosterol could be used as the Lipid-lowering drugs, and it could also be used as the acridine and health food.

2. Properties of Beta-sitosterol
(1)ACD/LogP: 10.73; (2)# of Rule of 5 Violations: 1; (3)#H bond acceptors: 1; (4)#H bond donors: 1; (5)#Freely Rotating Bonds: 7; (6)Polar Surface Area: 9.23; (7)Index of Refraction: 1.521; (8)Molar Refractivity: 129.21 cm³; (9)Molar Volume: 424.3 cm³; (10)Polarizability: 51.22 ×10^-24 cm³; (11)Surface Tension: 37.6 dyne/cm; (12)Density: 0.97 g/cm³; (13)Flash Point: 220.4 °C; (14)Enthalpy of Vaporization: 88.77 kJ/mol; (15)Boiling Point: 501.9 °C at 760 mmHg; (16)Vapour Pressure: 3.53E-12 mmHg at 25°C; (17)Exact Mass: 414.386166; (18)MonoIsotopic Mass: 414.386166; (19)Topological Polar Surface Area: 20.2; (20)Heavy Atom Count: 30; (21)Complexity: 634.

3. Structure Descriptors of Beta-sitosterol
(1)Canonical SMILES: CCC(CCC(C)C1CCC2C1(CCC3C2CC=C4C3(CCC(C4)O)C)C)C(C)C
(2)Isomeric SMILES: CC[C@H](CC[C@@H](C)[C@H]1CC[C@@H]2[C@@]1(CC[C@H]3[C@H]2CC=C4[C@@]3(CC[C@@H](C4)O)C)C)C(C)C
(3)InChI: InChI=1S/C29H50O/c1-7-21(19(2)3)9-8-20(4)25-12-13-26-24-11-10-22-18-23(30)14-16-28(22,5)27(24)15-17-29(25,26)6/h10,19-21,23-27,30H,7-9,11-18H2,1-6H3/t20-,21-,23+,24+,25-,26+,27+,28+,29-/m1/s1
(4)InChIKey: KZJWDPNRJALLNS-VJSFXXLFSA-N 

4. Preparation of Beta-sitosterol
Beta-sitosterol has been synthesized from stigmasterol 1, which involves a specific hydrogenation of the side-chain of stigmasterol (See Figure Below). The first step in the synthesis forms stigmasterol tosylate 2 from stigmasterol 1 (95% purity) using p-TsCl, DMAP, and pyridine (90% yield). The tosylate 2 then undergoes solvolysis as it is treated with pyridine and anhydrous MeOH to give a 5:1 ratio of i-stigmasterol methyl ether 3 (74% yield) to stigmasterol methyl ether 4, which is subsequently removed by chromatography. The hydrogenation step of a previously proposed synthesis involved the catalyst Pd/C and the solvent ethyl acetate. However, due to isomerisation during hydrolysis, other catalysts, such as PtO₂, and solvents, such as ethanol, were tested. There was little change with the use of a different catalyst. Ethanol, however, prevented isomerisation and the formation of the unidentified impurity to give compound 5. The last step of the synthesis is deprotection of the β-ring double bond of 5 with p-TsOH, aqueous dioxane, and heat (80 °C) to yield β-sitosterol 6. The cumulative yield for the final two steps was 55%, and the total yield for the synthesis was 37%


5. Side effects of Beta-sitosterol
Beta-Sitosterol should be avoided during pregnancy and breast-feeding, since not enough is known about its effects on unborn and newborn children. β-Sitosterol is also not recommended for individuals with sitosterolemia, a rare inherited fat storage disease. Because people with this condition have too much β-sitosterol and related fats in their system, taking β-sitosterol will only worsen this condition. In addition, high levels of β-sitosterol concentrations in blood have been correlated with increased severity of heart disease in men having previously suffered from heart attacks

6. Use of Beta-sitosterol
Alone and in combination with similar phytosterols, β-sitosterol reduces blood levels of cholesterol, and is sometimes used in treating hypercholesterolemia.[medical citation needed] β-Sitosterol inhibits cholesterol absorption in the intestine. When the sterol is absorbed in the intestine, it is transported by lipoproteins and incorporated into the cellular membrane. Phytosterols and phytostanols both inhibit the uptake of dietary and biliary cholesterol, decreasing the levels of LDL and serum total cholesterol. Because the structure of β-sitosterol is very similar to that of cholesterol, β-sitosterol takes the place of dietary and biliary cholesterol in micelles produced in the intestinal lumen. This causes less cholesterol absorption in the body

7. Other details of Beta-sitosterol
When you deal with beta-sitosterol, you should be careful. For one thing, beta-sitosterol is irritant to eyes, respiratory system and skin, which may also cause inflammation to the skin or other mucous membranes. For another thing, it is harmful  which may cause damage to health, and it may have danger of serious damage to health by prolonged exposure through inhalation and if swallowed. Besides, it has the limited evidence of a carcinogenic effect. Therefore, you should take the following instructions to protect yourself. Wear suitable protective clothing, then avoid contacting with skin and eyes. If in case of contact with eyes, rinse immediately with plenty of water and seek medical advice. In addition, remember not to breathe dust.