J. Agric. Food Chem. 2001, 49, 2548−2551
Novel Method for Isolation of Major Phenolic Constituents from
Cashew (Anacardium occidentale L.) Nut Shell Liquid
R. Paramashivappa, P. Phani Kumar, P. J. Vithayathil, and A. Srinivasa Rao*
Vittal Mallya Scientific Research Foundation, P.O. Box 406, K. R. Road, Bangalore - 560 004, India
Commercially available cashew (Anacardiumoccidentale L.) nut shell liquid (CNSL) mainly contains
the phenolic constituents anacardic acid, cardol, and cardanol. These phenolic constituents are
themselves heterogeneous, and each of them contains saturated, monoene, diene, and trienes in
the fifteen-carbon side chain. This communication describes the separation of anacardic acid, cardol,
and cardanol for industrial application. Anacardic acidwas selectively isolated as calcium anacardate.
The acid-free CNSL was treated with liquor ammonia and extracted with hexane/ethyl acetate (98:
2) to separate the mono phenolic component, cardanol. Subsequently, ammonia solution was
extracted with ethyl acetate/hexane (80:20) to obtain cardol.
Keywords: Anacardic acid; cardol; cardanol; calcium salt; cashew nut shell liquid; Anacardiumoccidentale L.
Cashew (Anacardium occidentale L.) is one of the
well-known species of the Anacardiaceae family. India
is the largest producer and exporter of cashew kernel,
accounting for almost 50% of world exports. In 19981999 alone 75,000 metric tons of cashew kernel was
exported to different countries such as the U.S., Netherlands, U.K., Japan, U.A.E., and France. This amount
isalmost 100 times the amount of 1988-1989 exports
(courtesy: Cashew Export Promotion Council of India,
Cochin). The other important cashew nut producing
countries are Brazil, Mozambique, Tanzania, and Kenya. Cashew nut shell liquid (CNSL), a byproduct obtained during the processing of cashew nuts, is used in
the manufacture of industrially important products such
as cement, specialtycoatings, primers, etc. (1). The
major phenolic constituents of CNSL are cardol (Figure
1, 1-4), anacardic acid (Figure 1, 5-8), and cardanol
(Figure 1, 9-12). Anacardic acid inhibits enzymes such
as prostaglandin synthase (2), tyrosinase (3), and lipoxygenase (4). It is also known to exhibit antitumor
(5), antimicrobial (6), and antiacne (7) properties. Cardanol finds many applications in the formof phenolformaldehyde resins in varnishes, paints, and brake
linings (8). Even though cardol was reported to be toxic
(9), recent studies on rats show that there is tolerance
of up to 5 g/kg body weight (10). Cardol is also active
against the filarial parasite of cattle Setaria digitata
(10). In view of its biological and industrial applications
it was considered necessary to develop a simpleand
efficient method for the isolation of all the major
phenolic constituents of CNSL.
Because of the thermolability of the carboxylic group
of anacardic acid (tendency to get converted to cardanol),
CNSL constituents cannot be separated by fractional
distillation (11). General Foods Corporation (Rye, NY)
(12) was the first to report a method to isolate anacardic
acid as alkaline earthmetal salt. Although this method
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Figure 1. Structures of major phenolic constituents of CNSL.
is efficient, the purity of the product was not supported
by any modern chromatographic or spectral data. Later,
Nagabhushana et al (13) reported a column chromatographic method usingtriethylamine treated silica gel
for medium-scale isolation of anacardic acid from CNSL.
However, this process is not suitable for large-scale
isolation. At nearly same time, Tsunetaro et al (14)
isolated anacardic acid on ion-exchange resin using
organic solvents (nonaqueous) as mobile phase. This
method is not ideal for industrial isolation as use of
nonaqueous solvent affects the life...
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