New Guaianolide Sesquiterpene Lactones and Other Constituents from Pyrethrum pulchrum.

Pyrethrum pulchrum is a rare Mongolian plant species that has been traditionally used as an ingredient in various remedies. Bioactivity-guided fractionation performed on the methanol extract of its aerial parts led to the isolation of 2 previously undescribed guaianolide-type sesquiterpene lactones, namely 1ß,10ß-epoxy-8α-hydroxyguaia-3,11(13)-dien-6,12-olide (1: ) and 1,8,10-trihydroxyguaia-3,11(13)-dien-6,12-olide (2: ), along with the isolation or chromatographic identification of 11 compounds, arglabin (3: ), 3ß-hydroxycostunolide (4: ), isocostic acid (5: ), (E)-9-(2-thienyl)-6-nonen-8-yn-3-ol (6: ), (Z)-9-(2-thienyl)-6-nonen-8-yn-3-ol (7: ), N 1,N 5,N 10,N 14-tetra-p-coumaroyl spermine (8: ), chlorogenic acid (9: ), 3,5-di-O-caffeoylquinic acid (10: ), 3,5-di-O-caffeoylquinic acid methyl ester (11: ), 3,4-di-O-caffeoylquinic acid (12: ), and tryptophan (13: ). Their structures were assigned based on spectroscopic and spectrometric data. The antimicrobial, antiproliferative and cytotoxic activities of selected compounds were evaluated. The new compounds showed weak to moderate antimicrobial activity. Arglabin (3: ), the major sesquiterpene lactone found in the methanol extract of P. pulchrum, exhibited the highest activity against human cancer lines, while compound 1: also possesses significant antiproliferative activity against leukemia cells.

Bioactive flavonoids from plant extract of Pyrethrum pulchrum and its acute toxicity.

Pyrethrum pulchrum Ledeb. has been a phytochemically unexplored Mongolian medicinal folklore plant. In this study, its total flavonoid content was determined and fourteen flavonoids (1-14) were isolated from the aerial parts of P. pulchrum. Their structures were elucidated on the basis of spectroscopic data. The compounds 12-14, methoxyflavones, were tested for antiproliferative and cytotoxic activity against A549, HeLa, K-562, THP-1 and HUVEC cell lines. This is the first report on the effects of 5,7,4'-trihydroxy-3,6,3'-trimethoxyflavone (13) against all tested cell lines and it exhibited potent activity against chronic myeloid leukemia K-562 and acute monocytic leukemia THP-1 cells, each with GI50 value at 2.0 µg/mL. The 5,4'-dihydroxy-3,6,7,3'-tetramethoxyflavone (14) showed the most potent activity against THP-1 (GI50 = 1.1 µg/mL) and the highest cytotoxicity (5.6 µg/mL). In addition, acute toxicity of plant ethanol extract was evaluated and the lethal dose (LD50) was estimated at 1048 mg/kg.