Antioxidative Phenylethanoid and Phenolic Glycosides from Picrorhiza scrophulariiflora

Abstract

The plant Picrorhiza scrophulariiflora PENNELL (Scrophulariaceae) grows in high-altitude regions (above 4400 m) in southeast Tibet and northwest Yunnan province in China. The root of this plant is used in traditional Chinese medicine for the treatment of damp-heat dysentery, jaundice, and steaming of bone.1) Picrorhiza kurrooa, the other unique species of the same genus, is also widely utilized in India for the treatment of jaundice, indigestion, common fever, acute viral hepatitis, and bronchial asthma.2) The hepatoprotective action of P. kurrooa is not fully understood but may be attributed to inhibition of the generation of oxygen anions and scavenging of free radicals.3) Picroside I and kutkoside, iridoid glycosides obtained from P. kurrooa, were reported to be scavengers of superoxide anion radicals.4) Iridoid glycosides, triterpenoids, phenolic glycosides, and phenylethanoid glycosides have been isolated from the roots of P. scrophulariiflora. 5-7)In our screening program searching for antioxidative natural substances from traditional Chinese medicine, the nBuOH portion from the ethanol extract of P. scrophulariiflora showed potent antioxidative activity evaluated based on its scavenging effects on hydroxyl radicals and superoxide anion radicals, with the concentrations exhibiting 50% inhibition (IC 50 ) being 2.82 and 1.98 mg/ml, respectively. Further bioassay-guided analysis led to the isolation of 10 phenylethanoid and phenolic glycosides from the active n-BuOH fraction from P. scrophulariiflora. In this paper, we describe the isolation and structure elucidation of a new phenylethanoid glycoside, scroside D (2), along with nine known glycosides obtained from this plant. The antioxidative activities of these 10 glycosides were evaluated based on their scavenging effects on hydroxyl radicals produced by H 2 O 2 /Fe 2ϩ , and superoxide anion radicals produced by xathine/xanthine oxidase systems. Results and DiscussionThe ethanol extract of the plant was suspended in water and then successively extracted with petroleum ether (60-90°C), EtOAc, and n-BuOH. The n-BuOH portion was chromatographed repeatedly on silica gel, C 18 , and Sephadex LH-20 to afford compounds 1-10. The other nine known glycosides were subsequently identified as 2-(3,4-dihydroxy-plantainoside D (6), 10) scroside A (7), 7) androsin (8) Medicine and Natural Products, Jinan University; Guangzhou 510632, P. R. China. Received November 11, 2003; accepted January 20, 2004 One new phenylenthanoid glycoside, scroside D (2), was isolated from the roots of Picrorhiza scrophulariiflora ( The structures of these compounds were elucidated using spectroscopic methods. The antioxidative activities of these isolated compounds were evaluated based on their scavenging effects on hydroxyl radicals and superoxide anion radicals, respectively. Compounds 1, 2, and 6 showed potent antioxidative effects as those of ascorbic acid and the structure-activity relationship is discussed.

Unusual iridoid glycosides in Veronica sects. Hebe and Labiatoides

“…Pungenin (20b) is here reported for the first time in the genus, it has previously only been found in Pinaceae. Otherwise, acetophenone glucosides are not uncommon in angiosperms; in Plantaginaceae, 20a has been reported from both species of Picrorhiza (Stuppner and Wagner, 1989;Wang et al, 2004), one species of Globularia (Calis et al, 2002), and four species of Penstemon (Junior, 1984;1986;Stermitz et al, 1993;Vesper and Seifert, 1994). However, due to its occasional occurrence, picein shows limited chemosystematic promise.…”

Two Phenylpropanoid Glycosides from Neopicrorhiza scrophulariiflora

“…The EtOAc-soluble portion was placed on a silica gel column and eluted sequentially with CHCl 3 /MeOH mixtures (1 : 0, 50 : 1, 10 : 1, 5 : 1, 1 : 1, 0 : 1) to give ten fractions (frs. [1][2][3][4][5][6][7][8][9][10] Enzymatic Hydrolysis of 1 and 2 A solution of each compound (1, 2) (2 mg) in H 2 O (1.0 ml) and b-D-glucosidase (10 mg) from almonds was incubated at 37°C for 25 h. The solution was subsequently washed with EtOAc and the aqueous layer was evaporated to yield a residue that showed a spot Vol. 54, No.…”

“…1. Though several phenylpropanoid glycosides with a phenylethyl group at C-1Ј of the glucose moiety have been reported, 4,6) this is the first time that one with an acetophenoyl group at C-1Ј of glucose has been identified.…”

“…2,3) Earlier investigations of this plant led to the isolation of triterpenoids, iridoid glycosides, phenolic glycosides and phenylethanoid glycosides. [3][4][5][6] Recently, the Ministry of Health, Labour and Welfare of Japan began to study the reclassification of the raw materials exclusively used as pharmaceuticals, 7) and a number of herbs were investigated for their toxicity and secondary metabolites. As part of this study, we have isolated two new phenylpropanoid glycosides, scrophulosides A (1) and B (2), along with two known compounds, androsin (3) and picroside I, from the rhizomes of this plant of herbal medicines market in Japan.…”

Screening of glycoside isomers in P. scrophulariiflora using ionic liquid‐based ultrasonic‐assisted extraction and ultra‐performance liquid chromatography/electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

“…The plant is found in high‐altitude regions (above 4400 m) in the southeast of Tibet and the northwest of Yunnan in China. Iridoid glycosides, phenylethanoid glycosides, and cucurbitacin glycosides are significantly bioactive ingredients of this plant . The high polarity, low stability, low abundance, and structural diversity of the iridoid glycosides, phenylethanoid glycosides, and cucurbitacin glycosides make it difficult to simultaneously identify and quantify the compounds using traditional phytochemical protocols.…”