18-carbon fatty acids

[nochirality]

If the melting points of these 18-carbon fatty acids are like this, stearic acid, 69.6 °C, oleic acid, 13.4 °C, linoleic acid, -5 °C, and linolenic acid, -11 °C, then what structural aspect of these 18-carbon fatty acids is associated with their melting points? And also, what would be the molecular explanation for the trend in the melting points?

 

So I'm thinking that the reason for this is because of their double bonds. How many double bonds they have would raise their melting points!

 

This is my first post, I wonder if I got this right

[ecoli]

steric acid

 

 

oleic acid

 

linoleic acid

 

 

linolenic acid

 

The differences in melting point, since they are pretty similar in overall structure, will probably be due to their most obvious differences. Namely, the number of double bonds.

 

Now, why do you think having more double bonds will lower the melting point?

[Realitycheck]

Man, just today, I've been finding a bunch of bad press about linoleic acid - like carcinogenic and tumor-growth promotion. As opposed to conjugated linoleic acid, which is actually a trans fat, that is actually good for you. Of course, the conjugated linoleic acid is found in cow meat and milk, while the linoleic acid is found in the flax oil that I have been making my salad dressing with for the last 2 or 3 years.

 

My pathologist just told me that it was most likely caused by a "random genetic mutation", but I don't really buy it, given the timing of it all, though he did show me an article showing flax oil's benefits in reducing cancer in rats, and I found plenty of other supporting documentatin for LA. What I am wondering is how the hell can you have a mid-life random genetic mutation??????!!!!!!!! I have never heard of that. Sorry for the hijack.

[nochirality]

"Now, why do you think having more double bonds will lower the melting point?"

 

-No... I meant that double bonds would raise the melting point... I never said that it would lower it...

 

"As opposed to conjugated linoleic acid, which is actually a trans fat, that is actually good for you."

 

-isn't trans fat bad for you...? I thought it was the cis that was beneficial.

 

Incidentally.... if branched-chain fatty acids were to be found in a few bacterial membrane lipids, would them being there increase or decrease the fluidity of the membranes, which in other words would basically give them a lower or higher melting point?

[Realitycheck]

Actually, it looks like it gets off on a technicality.

 

Conjugated linoleic acid is a trans fat, though some researchers claim that it is not harmful in the same fashion as other trans fatty acids, but rather is beneficial.[3] CLA is a conjugated system, and in the United States, trans linkages in a conjugated system are not counted as trans fat for the purposes of nutritional regulations and labeling.

 

Various antioxidant and anti-tumor properties have been attributed to CLA, and studies on mice and rats show promising results in reducing mammary, skin, and colon tumor growth [6]

 

A European team led by the Swiss scientist Lukas Rist has found that mothers consuming mostly organic milk and meat products have about 50 percent higher levels of rumenic acid in their breast milk. [7]

 

Studies on CLA in humans show a tendency for reduced body fat[8] particularly abdominal fat, changes in serum total lipids and decreased whole body glucose uptake. The maximum reduction in body fat mass was achieved with a 3.4 g daily dose[9]. CLA supplementation has, however, been shown to increase C-reactive protein levels, to possibly induce oxidative stress[10], to reduce insulin sensitivity and to increase lipid peroxidation.[11]. However, the significance of these findings is unknown, and other studies suggest that CLA may protect cells from oxidative damage by increasing glutathione levels without inducing lipid peroxidation[12]. It remains possible, however, that observations of increased markers of lipid oxidation may be related to potentially desirable lipolytic effects. Further studies are necessary to establish clinical significance.

 

http://en.wikipedia.org/wiki/Conjugated_linoleic_acid

 

Maybe that's why I started eating a lot more beef all of a sudden.