Kleinhospitine E and Cycloartane Triterpenoids from Kleinhovia hospita

Abstract

A novel cycloartane triterpenoid alkaloid, kleinhospitine E (1), six new cycloartane triterpenoids (2-7), three known cycloartane triterpenoids (8-10), and taraxerone (11) were isolated from a methanol extract of Kleinhovia hospita. Their structures were elucidated by 1D- and 2D-NMR spectroscopy as well as HRMS analysis. The absolute configurations of all isolated compounds were determined from their ECD spectra by comparison with theoretical values. Kleinhospitine E (1) is the first cycloartane alkaloid possessing an unusual γ-lactam with an oxopropylidene side chain. Compounds 2, 3, and 6 were assigned as cycloartane triterpenoids with a 9α,10α-cyclopropyl ring, which is found rarely among naturally occurring compounds, while 4 and 5 were established as isomers of compound 3 containing a 21,23-diacetal side chain. Biological evaluation revealed that compounds 4 and 9 exhibited more potent antiproliferative activities against a multidrug-resistant tumor cell line compared with its parent chemosensitive cell line. Furthermore, compound 6 exhibited submicromolar anti-HIV activity.

Semi-synthesis and cytotoxicity evaluation of pyrimidine, thiazole, and indole analogues of argentatins A–C from guayule (Parthenium argentatum) resin

“…Argentatins A-C (1-3) obtained from guayule resin [28], were used for the synthesis of their target pyrimidine, thiazole, and indole analogues as outlined in Schemes 1 and 2. Depicted in Scheme 1 is the synthesis of pyrimidine analogues (7)(8)(9)(10)(11)(12). Claisen-Schmidt condensation [22] of 1-3 with benzaldehyde afforded their corresponding benzylidene intermediates 4-6 in 74-77% yield, which were the key precursors for the synthesis of their pyrimidine analogues.…”

“…All twelve synthetic analogues (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) and their parent argentatins A-C (1-3) were evaluated for their cell proliferation inhibitory activity against a panel of three human sentinel cancer cell lines [NCI-H460 (non-small cell lung cancer), MCF-7 (breast adenocarcinoma), SF-268 (CNS cancer, glioma)] and normal human primary fibroblast (WI-38) cells by using the MTT assay [32]. Doxorubicin and DMSO were used as positive and negative controls, respectively.…”

“…Triterpenoids, one of the major classes of NPs, have been reported to exhibit a variety of biological activities [6,7]. Among these, cycloartane-type triterpenoids are found widely in plants and algae, some of which are known to display cytotoxic activity [8,9]. Cycloartane-type triterpenoids, such as argentatins A-C, have been found to be the major chemical components in Parthenium argentatum Gray (guayule) resin [10,11], which is one of the byproducts in the manufacture of natural rubber from guayule, a widely-investigated arid land crop of potential industrial importance [12−14].…”

Review Fitokimia, Aneka Produk dan Manfaat Dari Ekstrak Daun Tahongai (Kleinhovia hospita L.)

“…Selain saponin zat aktif lainnya adalah cardenolin, bufadienol dan antrakinon (Raflizal dan Sihombing, 2009) dan juga fenol (Dini & Darminto, 2012). Rahim et al, (2018) berhasil mengisoalsi ekstrak metanol K. hospita L. dan memperoleh senyawa alkaloid triterpenoid cycloartane baru, kleinhospita E, enam triterpenoid cycloartane baru, tiga triterpenooid cycloartane dan taraxerone. Secara kuantitatif ekstrak etanol daun tahongai mengandung alkaloid 2,83%, flavonoid 19,78% dan saponin 14,23% dan mengandung flavonoid yang ditunjukkan adanya ikatan O-H, ikatan rangkap C=C dan ikatan C-H (Yunita et al, 2019).…”

Recent advances in natural anti‐HIV triterpenoids and analogs

“…Compounds 189 , 190 , and 194 were assigned as cycloartane triterpenoids with a 9α,10α‐cyclopropyl ring, which is found rarely among naturally occurring compounds, while 192 and 193 were established as isomers of 190 containing a 21,23‐diacetal side chain. Compound 194 exhibited anti‐HIV activity with an EC 50 value of 0.8 μM 101 …”