Abstract
Given that harvesting time has a great impact on the quality of herbal
medicine, knowing the ontogenesis in the chemical profile aspect is
essential to determine the optimal harvesting season. A high-throughput and
versatile approach (herbal infrared macro-fingerprinting) harmonizing with
the character of herbal medicine and providing the whole chemical profile
(entirety), group analogues (part), and single compounds (major components)
is developed to rapidly disclose the variation rule of the full chemical
profile of herbal medicine over a growing season without extraction
pretreatments, and thus to determine the optimal harvesting period in
respect to groups of chemical compounds using Scutellaria baicalensis
as a demonstration. IR macro-fingerprints of Scutellaria baicalensis
harvested in the same period have a high similarity (> 0.91) despite
small variations, suggesting that IR macro-fingerprinting can faithfully
reflect the spectacle of “disordered order” in nature. From Year-1 spring to
Year-3 autumn, general contents (%, w/w) of total flavonoids fluctuate up
and down with a maximum value in Year-2 spring, and that of saccharides is
relatively stable except for the attenuation from Year-2 autumn to Year-3
spring. From Year-1 autumn to Year-2 spring, flavonoid aglycones initially
produced in Scutellaria baicalensis are extensively transformed to
responding flavonoid glycosides. From Year-2 spring to Year-3 autumn,
flavonoid glycosides are converted back to their corresponding aglycones.
The best seasons for collecting Scutellaria baicalensis with a high
content of flavonoid glycosides and aglycones would be Year-2 spring and
Year-3 spring, respectively.
Key words
Scutellaria baicalensis Georgi - Labiatae - herbal medicine - ontogenesis - infrared spectroscopy - flavonoids - baicalin
