Brazilian natural medicines. IV. New noroleanane-type triterpene and ecdysterone-type sterol glycosides and melanogenesis inhibitors from the roots of Pfaffia glomerata.

The ethyl acetate and 1-butanol soluble fractions of the roots of Pfaffia glomerata were found to show inhibitory effects on melanogenesis in theophylline-stimulated B16 melanoma 4A5 cells. From the ethyl acetate and 1-butanol soluble fractions, we isolated a new noroleanane-type triterpene, pfaffianol A, its glycosides, pfaffiaglycosides A and B, and ecdysterone-type sterol glycosides, pfaffiaglycosides C, D, and E, together with eight known constituents. The structures of new constituents were determined on the basis of physicochemical and chemical evidence. Among them, pfaffianol A (IC(50)=44 microM) and pfaffoside C (IC(50)=92 microM) substantially inhibited melanogenesis without cytotoxic effects. The inhibitory effects were stronger than that of reference compound, arbutin (IC(50)=174 microM).

Structures of new flavonoids and benzofuran-type stilbene and degranulation inhibitors of rat basophilic leukemia cells from the Brazilian herbal medicine Cissus sicyoides.

Three new flavonoid glycosides (cissosides I, II, and III) and a new benzofuran-type stilbene (cissusin) were isolated from the methanolic extract of the aerial parts of Cissus sicyoides cultivated in Brazil. Their structures were elucidated on the basis of chemical and physicochemical evidence. The inhibitory effects of the isolated constituents on the release of beta-hexosaminidase as a marker of degranulation in rat basophilic leukemia (RBL-2H3) cells were examined. Cissusin, flavonols (kaempferol, quercetin), flavones (7,3',4'-trihydroxyflavone, lanceolatin B), pterocarpanes (homopterocarpin), chalcones (isoliquiritigenin, E-7-O-methylpongamol), and tryptanthrin markedly inhibited the release of beta-hexosaminidase.

Brazilian natural medicines. III. structures of triterpene oligoglycosides and lipase inhibitors from mate, leaves of ilex paraguariensis.

The methanolic extract from the leaves of Ilex paraguariensis (Aquifoliaceae) was found to show an inhibitory activity on porcine pancreatic lipase. From the methanolic extract, three new triterpene oligoglycosides, mateglycosides A, B, and C, were isolated together with 18 known compounds. The chemical structures of new oligoglycosides were elucidated on the basis of chemical and physicochemical evidence. Several constituents showed inhibitory activities on pancreatic lipase.

Steroidal saponins and pseudoalkaloid oligoglycoside from Brazilian natural medicine, "fruta do lobo" (fruit of Solanum lycocarpum).

Steroidal saponins, lyconosides Ia, Ib, II, III, and IV and a steroidal pseudoalkaloid oligoglycoside, lobofrutoside, were isolated from a Brazilian natural medicine, "fruta do lobo" (the fruit of Solanum lycocarpum St. Hil.). The chemical structures of these compounds were elucidated on the basis of analysis of chemical and physicochemical evidence.

Structures of steroidal alkaloid oligoglycosides, robeneosides A and B, and antidiabetogenic constituents from the Brazilian medicinal plant Solanum lycocarpum.

In the course of our studies on antidiabetogenic compounds from natural medicines and medicinal foodstuffs, a methanolic extract of the fruits of Solanum lycocarpum showed an inhibitory effect on the increase of serum glucose levels in oral sucrose-loaded rats. Through bioassay-guided separation, three known steroidal alkaloid oligoglycosides, solamargine (1), solasonine (3), and 12-hydroxysolasonine (5), were isolated from the active fraction together with two new steroidal alkaloid oligoglycosides, robeneosides A (2) and B (4). The major constituents, solamargine (1) and solasonine (3), exhibited an inhibitory effect on the increase of serum glucose levels in oral sucrose-loaded rats. In addition, these compounds suppressed gastric emptying in mice. However, this methanolic extract from S. lycocarpum fruits did not have any effect on intestinal alpha-glucosidase (sucrase and maltase) in vitro. It was concluded that these steroidal alkaloid oligoglycosides, 1 and 3, inhibited the increase of rat serum glucose levels by suppressing the transfer of sucrose from the stomach to the small intestine.