Bioactive Arabinogalactan-Proteins and Related Pectic Polysaccharides in Sino-Japanese Herbal Medicines

Abstract

Many plants have long been used as traditional herbal medicines. Because chronic disorders of an endogenous nature and pressing medical problems such as non-specific, constitutional or psychosomatic diseases have increased during the second half of the 20th century, traditional herbal medicines have begun to attract worldwide attention (Yamada 1994a). Herbal extracts used in Sino-Japanese traditional herbal medicines contain both low- and high-molecular-weight substances. The former include alkaloids, terpenoids, saponins and flavonoids, whereas the latter include proteins, tannins and polysaccharides in the hot water extract. Although biologically active substances with low molecular weight in medicinal herbs have been well studied and characterized, they can not account for all of the clinical effects achieved. Among the high-molecular-weight components of medicinal herbs, polysaccharides have been shown to possess a variety of pharmacological activities. Most especially, pectic polysaccharides containing arabinogalactan have been shown to have immunostimulating, antiulcer, anti-metastasis, hypoglycemic or other activities. (Yamada 1994b 1996, Yamada and Kiyohara 1999). These observations suggest that pectic polysaccharides are involved in the efficacy of traditional herbal medicines.