Isolation of Exosome-Like Nanoparticles and Analysis of MicroRNAs Derived from Coconut Water Based on Small RNA High-Throughput Sequencing

In this study, the presence of microRNAs
in coconut water was identified
by real-time polymerase chain reaction (PCR) based on the results
of high-throughput small RNA sequencing. In addition, the differences
in microRNA content between immature and mature coconut water were
compared. A total of 47 known microRNAs belonging to 25 families and
14 new microRNAs were identified in coconut endosperm. Through analysis
using a target gene prediction software, potential microRNA target
genes were identified in the human genome. Real-time PCR showed that
the level of most microRNAs was higher in mature coconut water than
in immature coconut water. Then, exosome-like nanoparticles were isolated
from coconut water. After ultracentrifugation, some particle structures
were seen in coconut water samples using 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine
perchlorate fluorescence staining. Subsequent scanning electron microscopy
observation and dynamic light scattering analysis also revealed some
exosome-like nanoparticles in coconut water, and the mean diameters
of the particles detected by the two methods were 13.16 and 59.72
nm, respectively. In conclusion, there are extracellular microRNAs
in coconut water, and their levels are higher in mature coconut water
than in immature coconut water. Some exosome-like nanoparticles were
isolated from coconut water, and the diameter of these particles was
smaller than that of animal-derived exosomes.