Bioactivity and chemistry of the genusHortonia

Abstract

The dichloromethane extracts of the leaves, stem bark, bark and the roots of the three species of the primitive endemic genus Hortonia, H. angustifolia, H. floribunda and H. ovalifolia, collected from nine geographical locations ranging from lower elevations (84-420 m) to higher (2000 m) showed comparable HPLC profiles and mosquito larvicidal and antifungal activities; protein analysis of the leaves of the three species of Hortonia showed identical peaks and bands. The two major metabolites (4S)-4-methyl-2-(11-dodecynyl)-2-butenolide (2) and (4S)-4-methyl-2-(11-dodecenyl)-2-butenolide (3), which were previously reported from all three plants, showed potent larvicidal activities. Compound 2 was excessively high in the extracts of the stem bark and the roots of all three species amounting to approximately 38 and 60%, respectively. A minor new butenolide (4), (4S)-4-methyl-2-((2R)-hydroxy-11-dodecenyl)-2-butenolide, with much reduced larvicidal activity and ishwarane (1), which showed antifungal activity, were also isolated from all three plants. Treatment of compound 2 with H(2)/Pd-C afforded the completely reduced compound 5, which showed no larvicidal activity, indicating that unsaturation in both 2 and 3 is necessary for their bioactivity. The foregoing evidence showed that there are major similarities between the three species of Hortonia.

Germacrene A–A Central Intermediate in Sesquiterpene Biosynthesis

“…[198] Its further conversion by acetalisation, hydroboration and oxidation leads to 89,t hat upon deacetalisation and retroaldol reaction resultsi n90.R eduction through the bis-semicarbazoney ields (+ +)-nootkatane (77), thus firmly establishing the absolutec onfiguration of 73. [199] Ishwarane was subsequently also found in many other plants, [185,[200][201][202][203][204] while 8,12-seco-ishwaran-12-ol (74,[ a] D = À165, c 0.1, CHCl 3 )h as only once been reported from Litsea amara. [205] Its absolutec onfiguration has not been formally established, butw as suggested to correspond to that of 73.F ull 13 C-NMR data for 73 and 74 are available.…”

“…Reduction through the bis‐semicarbazone yields (+)‐nootkatane ( 77 ), thus firmly establishing the absolute configuration of 73 [199] . Ishwarane was subsequently also found in many other plants, [185, 200–204] while 8,12‐ seco ‐ishwaran‐12‐ol ( 74 , [α] D =−165, c 0.1, CHCl 3 ) has only once been reported from Litsea amara [205] . Its absolute configuration has not been formally established, but was suggested to correspond to that of 73 .…”

Erythrofordins D and E, two new cassaine-type diterpenes from Erythrophleum suaveolens

“…As part of a screening campaign aimed at the identification of anti-cancer active natural product leads, this collection has been progressively screened in the NCI's 60 human tumor cell anticancer drug screen (NCI-60), initially as a one-dose prescreen at a nominal concentration of 100 μg/mL, with select cytotoxic extracts and fractions undergoing further five-dose and, in some cases, invivo evaluations. 1 The NCI's Natural Product Repository plant collection has been a rich and prolific source of biologically active and chemically diverse small molecules, recently exemplified by the englerins, guaiane sesquiterpenes isolated from Phyllanthus engleri exhibiting potent selectivity against renal cancer cell lines; 2 and the schweinfurthins, prenyl stilbenes isolated from the plants of the genus Macaranga displaying selectivity for the central nervous system and leukemia cell lines. 3,4 In continuation of work focused on the identification of anti-cancer natural products from plants, the organic solvent extract of the plant Erythrophleum suaveolens (Fabaceae), displayed potent NCI-60 cell, hollow fiber and xenograft activity (see Supporting Information (SI), Figure S1-4 and Table S1) and was selected for scale-up bioassay-guided natural product isolation work.…”

A novel Tetracyclic Sesquiterpene from the Genus <em>Hortonia</em>

“…We have previously reported the isolation of several biologically active and unique natural products from the three species of genus Hortonia ( Ratnayake et al, 2001;Ratnayake et al, 2008a;Ratnayake et al, 2008b;Ratnayake et al, 2008c;Carr et al, 2012). As part of our continuing research to find biologically active compounds from this plant, we isolated one tetracyclic sesquiterpene.…”