New research suggests that vitamin B3 may have been delivered to Earth by asteroids during Earth's early days; this finding supports the idea that life on Earth was spawned from extraterrestrial molecules.
"It is always difficult to put a value on the connection between meteorites and the origin of life; for example, earlier work has shown that vitamin B3 could have been produced non-biologically on ancient Earth, but it's possible that an added source of vitamin B3 could have been helpful," Karen Smith of Pennsylvania State University, said in a NASA news release. "Vitamin B3, also called nicotinic acid or niacin, is a precursor to NAD (nicotinamide adenine dinucleotide), which is essential to metabolism and likely very ancient in origin."
The researchers made their finding by looking at samples of "eight different carbon-rich meteorites," the news release reported. These objects are called "CM-2 type carbonaceous chondrites"; the team found these objects had vitamin B3 levels ranging from 30 to 600 parts-per-billion.
"We discovered a pattern - less vitamin B3 (and other pyridine carboxylic acids) was found in meteorites that came from asteroids that were more altered by liquid water. One possibility may be that these molecules were destroyed during the prolonged contact with liquid water," Smith said. "We also performed preliminary laboratory experiments simulating conditions in interstellar space and showed that the synthesis of vitamin B3 and other pyridine carboxylic acids might be possible on ice grains."
Researchers believe a dense dust cloud filled with dust and ice grains collapsed in on itself; clumps of different types of sediment are believed to have combined to form moon-sized objects which eventually could have formed planets.
In this scenario, radiation from nearby stars and other powerful objects could have spurred chemical reactions in nebulae leading to the creation of vitamin B3.
When asteroids collide with meteors it causes smaller pieces to break off, which are the meteorites that sometime plummet to Earth. These objects tend not to be found for extended periods of time after they first touchdown, allowing them to be contaminated by terrestrial molecules.
The vitamin B3 in these samples is believed to be of extraterrestrial origins because it was found along with structural isomers, which are "related molecules that have the same chemical formula but whose atoms are attached in a different order."
"Non-biological chemistry tends to produce a wide variety of molecules -- basically everything permitted by the materials and conditions present -- but life makes only the molecules it needs. If contamination from terrestrial life was the source of the vitamin B3 in the meteorites, then only the vitamin should have been found, not the other, related molecules," the news release reported.
