An Unlikely Treasure
Perilla Leaf, Seed, and Stem
Perilla is a mint plant (Laminaceae Family), Perilla
frutescens, growing in the hills and
mountains of East Asia (mainly India, China, Japan, and Korea). It has been
spread around the globe during the previous century; initially it was desired as
a decorative garden plant, but then it escaped cultivation; as an example, it
now grows in spots throughout most of the Eastern and Midwestern United States,
described as an invasive weed. The plant has long been used as a source of herb
materials for Chinese medicine; it is known in China as
zisu. The character
zi refers to the distinctive
purple color of the stem; in some varieties or under certain growing conditions,
the leaves also display a red-purple coloration; green leaves are more commonly
found, while some varieties have one side of the leaf being green and one side
red-purple. The character su
means comfort, and refers to the comforting effect of perilla leaves when taken
as a tea. Two parts of the plant are commonly used in Chinese medicine: the
leaf (ye) and the seed
(zi), respectively called
zisuye and
zisuzi (or Zi Su
Ye and Zi Su Zi); some herbalists use the stem separately or mixed
with the leaves. Jiao Shude has a good description of the different plant
parts.
Perilla is also used as a food source (2). The
crispa variety of perilla, which has
“crisped” leaves (curled along the edges), is known in Japan as shiso leaf (or
jiso; this is the Japanese
version of the word zisu), used
in preparing some sushi dishes and in making pickled plums
(umeboshi). The leaves of perilla are
used as a garnish or flavoring for some Vietnamese dishes. In China, Hunan
cuisine may include perilla leaves in preparing fish. The seeds are used in
Japan as a source of oil for cooking, and this oil has been developed as a
specialty health product marketed internationally because it is rich in omega-3
fatty acids. Perilla seed is used in making some Indian curries. The seeds are
a major food in Korea, used plain and roasted, as well as a source of cooking
oil; annual production of perilla seeds in Korea is about 40,000 metric
tons.
Perilla Leaf
In the modern Chinese Materia Medica, perilla leaf is
categorized as a surface-relieving herb used for common cold and similar types
of acute disorders that might involve stuffy nose, cough, and headache; it is
considered best for treating “wind-cold” type disorders, and is
classified as pungent and warm. Perilla leaf (and especially the stem) is also
considered valuable for dispersing stagnant qi and calming the mind. This dual
use is also noted for bupleurum (chaihu), classified as a surface
relieving herb but commonly employed for regulating qi and calming the mind; a
combination of bupleurum, perilla leaf, curcuma, and acorus is used for treating
depression. Other surface relieving herbs are sometimes used by Chinese doctors
as qi-regulating herbs, such as siler (fangfeng) included in Tong
Xie Yao Fang, and mentha (bohe) included in Xiao Yao
San.
Perilla leaf is aromatic,
with main active ingredients being volatile oils dominated by monoterpenes (3).
Among these components are perillaldehyde (the major flavor and fragrance
constituent; structure shown left), perillene, β-caryophyllene, thujopsene,
β-farnesene, limonene, elsholtziaketone, perillaketone, furylketone, linalool,
and trans-citral. The leaves also contain some larger molecules as active
components, such as ursolic acid (a triterpene glycoside) and rosmarinic acid
(structure shown right). The red-purple coloration of the stem (and leaves,
when so-colored) has been attributed to anthocyanins and flavones, such as
luteolin; a specially prepared perilla extract rich in these compounds is sold
as a food color for beverages, jams, and candies; it is red in acid pH (but
green at basic pH).
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