Basella alba L. (Malabar
Spinach) as an Abundant Source of Betacyanins: Identification, Stability,
and Bioactivity Studies on Natural and Processed Fruit Pigments
The antioxidant and
anti-inflammatory activities of acylated
and
decarboxylated gomphrenins, as well as Basella alba L. fruit extract, were investigated in relation to gomphrenin, known
for its high biological potential. The most abundant natural acylated
gomphrenins, namely, 6′-O-E-caffeoyl-gomphrenin (malabarin) and 6′-O-E-4-coumaroyl-gomphrenin (globosin), were isolated
from B. alba extract for the studies.
In addition, controlled thermal decarboxylation of gomphrenin in the
purified B. alba extract at 65–75
°C resulted in the formation of the most prevalent decarboxylated
products, including 17-decarboxy-gomphrenin and 2,17-bidecarboxy-gomphrenin,
along with their isoforms. The structures of the decarboxylated pigments
were confirmed by NMR analyses. Exploring the matrix effect on pigment
reactivity revealed a tremendous increase in the stability of all
betacyanins after the initial stage of extract purification using
a cation exchanger under various conditions. This indicates the removal
of a substantial portion of the unfavorable matrix from the extract,
which presumably contains reactive species that could otherwise degrade
the pigments. Furthermore, the high concentration of citrates played
a significant role in favoring the formation of 2-decarboxy-gomphrenin
to a considerable extent. In vitro screening experiments
revealed that the tested compounds demonstrated strong anti-inflammatory
properties in lipopolysaccharide (LPS)-activated human macrophages.
This effect encompassed the selective inhibition of cytokine and chemokine
release from activated macrophages, modulation of the chemotactic
activity of immune cells, and the regulation of tissue remodeling
mediators’ release.