Masazumi Miyakoshi

Cancer preventive agents. Part 8: Chemopreventive effects of stevioside and related compounds

In a search for potential cancer chemopreventive agents from natural resources, stevioside (1), a sweetener, and six related compounds, including two aglycones steviol (6) and isosteviol (7), were screened in an in vitro assay for inhibitory effects on Epstein-Barr virus early antigen activation. Compounds 1, 6 and 7 showed significant activity in this assay and also exhibited strong inhibitory effects in a two-stage carcinogenesis test using mouse skin induced by 7,12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA). The inhibitory effects of these three compounds were greater than that of glycyrrhizin. Furthermore, these three compounds significantly inhibited mouse skin carcinogenesis initiated by peroxynitrite and promoted by TPA. Their activities were comparable to that of curcumin. These results suggested that 1, as well as 6 and 7, could be valuable as chemopreventive agents for chemical carcinogenesis.

Oleanolic acid saponins from root-bark of Aralia elata.

Three new oleanolic acid glycosides, tarasaponins I-III, were isolated as their methyl esters from the root bark of Aralia elata together with four known glycosides, the methyl esters of chikusetsusaponins IVa, IV, 28-desglucosyl-chikusetsusaponin IV and pseudoginsenoside RT1. Tarasaponins I-III were characterized as oleanolic acid 3-O-[beta-D-glucopyranosyl(1-->3)][alpha-L-arabinofuranosyl(1-->4)[- beta-D-glucuronopyranoside, oleanolic acid 3-O-[beta-D-xylopyranosyl(1-->2)][beta-D-galactopyranosyl(1-->3)]-beta- D-glucuronopyranoside and beta-D-glucopyranosyl oleanolate 3-O-beta-D-galactopyranosyl(1-->3)-beta-D-glucuronopyranoside, respectively.

Studies on leguminous plants. Part XXXIV. Six New Triterpenoidal Glycosides Including Two New Sapogenols from Albizziae Cortex. V.

Six new triterpenoid glycosides called julibrosides A1-A4, B1 and C1 were isolated from Albizziae Cortex, the dried stem bark of Albizzia julibrissin Durazz. Their structures were determined based on spectral and chemical evidence. Julibrosides B1 and C1 had new sapogenols, designated julibrogenin B and C, respectively, while julibrosides A3 included N-acetyl-D-glucosamine as a sugar component.

Saponins from leaves of Acanthopanax sieboldianus

Two new triterpenoid saponins named sieboldianoside A and B were isolated from the leaves of Acanthopanax sieboldianus together with five known triterpenoid saponins, kalopanax-saponins A and B, saponin A, CP3, sapindoside B, and a known flavonol glycoside, kaempferol 3-O-rutinoside. On the basis of chemical and spectral evidence, the structures of the new saponins (sieboldianoside A and B) were concluded to be alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)- beta-D-glucopyranosyl esters of hederagenin and oleanolic acid 3-O-beta-D- xylopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopy ranosides, respectively.

Blood Pressure-Depressing Activity of a Peptide Derived from Silkworm Fibroin in Spontaneously Hypertensive Rats

Peptides showing inhibitory activity against the angiotensin I-converting enzyme (ACE) were investigated from the fibroin fraction of discarded silk fabric. Fibroin, which was hydrolyzed with alcalase after partial hydrolysis with hot aqueous 40% CaCl2, released two major active peptides showing ACE-inhibitory activity. The two peptides were identified as glycyl-valyl-glycyl-tyrosine (GVGY) and glycyl-valyl-glycyl-alanyl-glycyl-tyrosine (GVGAGY) by analyses with a protein sequencer and LC/MS/MS. GVGY, whose ACE-inhibitory activity has not previously been reported, showed a blood pressure-depressing effect on spontaneously hypertensive rat (SHR).

Lupane triterpenoid glycosyl esters from leaves of Acanthopanax divaricatus

Abstract Further investigation of the leaves of Acanthopanax divaricatus gave two analogues of chiisanoside, which is a lupane triterpenoid oligoglycosyl ester. The structures were established as 28- O -α- l -rhamnopyranosyl(1 → 4)-β- d -glucopyranosyl(1 → 6)β- d -glucopyranosyl esters of 1β,11α-dihydroxy-3-oxo-lup-20(29)-en-28-oic acid and 1( R ),11α,22α-trihydroxy-3,4-seco-lupa-4(23),20(29)-diene-3,28-dioic acid 3,11α-lactone based on chemical and spectroscopic evidence. in biosynthetic terms, one is the precursor of chiisanoside and the other is an oxygenated derivative chiisanoside.

Application of Saponin-Containing Plants in Foods and Cosmetics

Saponins are a class of natural products which are structurally constructed of aglycone (tri‐ terpene or steroid) and sugars (hexose and/or uronic acid). The name ‘saponin’ comes from soap as its containing plants agitated in water form soapy lather. Saponins are widely dis‐ tributed in many plants and are relatively widespread in our foodstuffs and herbal prepara‐ tions. Saponins traditionally used as a natural detergent. In addition to this physical property, plant-derived triterpenoid and steroidal saponins have historically received a number of industrial and commercial applications ranging from their use as sources of raw materials for the production of steroid hormones in the pharmaceutical industry, to their use as food additives and as ingredients in photographic emulsions, fire extinguishers and other industrial applications which take advantage of their generally non-ionic surfactant proper‐ ties [1-3]. They also exhibit a variety of biological activities, and have been investigated to‐ ward the development of new natural medicines and prove the efficacy of traditional herbal medicines [4]. Other interesting biological applications for various specific saponins include their uses as anti-inflammatory [5], hypocholesterolemic [6] and immune-stimulating [7] whose properties are widely recognized and commercially utilized.