Three lanostane triterpenoids with antitrypanosomal activity from the fruiting body of Hexagonia tenuis

Antitrypanosomal secondary metabolites from medicinal plants: a review

Human African trypanosomiasis (HAT) or sleeping sickness is caused by two subspecies of extracellular protozoan parasites, namely, Trypanosoma brucei gambiense and T. brucei rhodesiense. On the other hand, Chagas disease is caused by Trypanosoma cruzi. There are currently six drugs available for the treatment of African sleeping sickness, namely, pentamidine, suramin, melarsoprol, nifurtimox, eflornithine, and fexinidazole. Besides, benznidazole and nifurtimox are drugs that are currently used for the treatment of Chagas disease. Most of the current chemotherapies for the treatment of HAT and Chagas disease are unsuitable for prescription for various reasons including high toxicity, poor efficacy, undesirable route of administration, and drug resistance. Medicinal plants are potential sources of therapeutics for many diseases. Thus, a search for compounds from plants that are active against trypanosomes could pave the way to the discovery of antitrypanosomal drugs. Therefore, the current review evaluates the potential of the secondary metabolites from medicinal plants for antitrypanosomal drug development. The literature review in the field of antitrypanosomal secondary metabolites from medicinal plants has been documented. Hence, the present study involves the discussion of antitrypanosomal natural products from medicinal plants that were not reported in these review articles present in literature. The literature search was carried out in various databases including ScienceDirect, Google Scholar, tandfonline.com, Journal of Natural Products, MDPI, WILEY Online Library, tandfonline.com, and The Lancet. In this article, the secondary metabolites organized in different classes including alkaloids, terpenoids, and flavonoids that have potency against trypanosomes are discussed.

Isolation of C-29 oxygenated oleanane triterpenoids and a (+)-muurolene type sesquiterpenoid from the fruiting bodies of Fuscoporia torulosa and their bioactivities

Basidiomycetes with a wide variety of skeletons of secondary metabolites can be expected to be the source of new interesting biological compounds. During our research on basidiomycetes, two new C-29 oxygenated oleanane-type triterpenes (1 and 2) and torulosacid (3), a muurolene type sesquiterpenoid with a five-membered ether ring along with nine known compounds (4-12), were isolated from the MeOH extract of the fruiting bodies of Fuscoporia torulosa. The structures of 1-3 were determined by NMR and HREIMS analysis. Further studies on the stereochemistry of 3 were conducted using X-ray crystallographic analysis and comparison of experimental and calculated ECD spectra. In the antimicrobial assay of isolates, 1, 7, and 9 showed growth inhibitory activity against methicillin-resistant Staphylococcus aureus and other gram-positive strains. Isolation of oleanane type triterpenes from fungi including basidiomycetes, is a unique report that could lead to further isolation of new compounds and the discovery of unique biosynthetic enzymes.

Pentacyclic triterpenoids, fuscotorunones A and B, with ε-caprolactone in ring E from Fuscoporia torulosa

Fuscoporia torulosa (Pers.) (Hymenochaetaceae) is a mushroom forming woody fruiting body on living or dead trees. Two curious pentacyclic triterpenoids, fuscotorunones A and B, each of which has a unique ε-caprolactone in ring E, were isolated from the fruiting bodies of F. torulosa. The structures of fuscotorunones A and B were elucidated using MS analyses, IR spectrum and extensive 2D-homo and heteronuclear NMR data interpretation. Furthermore, a predicted biosynthetic pathway from 2,3-oxidosqualene to fuscotorunones A and B in F. torulosa is proposed.

Asymmetric Total Synthesis of (-)-Spirochensilide A, Part 1: Diastereoselective Synthesis of the ABCD Ring and Stereoselective Total Synthesis of 13(R)-Demethyl Spirochensilide A

A concise and diastereoselective construction of the ABCD ring system of spirochensilide A is described. The key steps of this synthesis are a semipinacol rearrangement reaction to stereoselectively construct the AB ring system bearing two vicinal quaternary chiral centers and a Co-mediated Pauson-Khand reaction to form the spiro-based bicyclic CD ring system. This chemistry leads to the stereoselective synthesis of 13(R)-demethyl spirochensilide A, paving the way for the first asymmetric total synthesis of (-)-spirochensilide A.

Triterpenes with unusual modifications from the fruiting bodies of the medicinal fungus Irpex lacteus

Ten previously undescribed triterpenoid congeners, namely irpeksolactins A-J, together with eighteen known ones, were isolated from the fruiting bodies of the rainforest-dwelling medicinal fungus Irpex lacteus. The structures of all the isolates were characterized by extensive spectroscopic approaches, including 1D & 2D NMR and MS spectroscopic methods. Irpeksolactin J displayed selective and weak cytotoxicity against the human lung cancer cell line A549 and the human hepatocellular carcinoma cell line SMMC-7721.

Triterpenoids

Covering 2014. Previous review: Nat. Prod. Rep., 2017, 34, 90-122 This review covers the isolation and structure determination of triterpenoids reported during 2014 including squalene derivatives, lanostanes, holostanes, cycloartanes, cucurbitanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, ursanes, hopanes, serratanes, isomalabaricanes and saponins; 374 references are cited.

Lanostane triterpenoids from Fomitopsis officinalis and their trypanocidal activity

Fomitopsis officinalis is a medicinal fungus, known as 'Agarikon', and is used traditionally in the treatment of asthma and rheumatism in Mongolia. The investigation of the chemical constituents of F. officinalis led to the isolation of 4 new lanostane triterpenoids together with 4 known triterpenoids. Inhibitory activity against Trypanosoma congolense, which causes fatal diseases in animals including livestock, was estimated for the isolated compounds. Compounds 2-5 and 8 exhibited moderate inhibition activities with IC₅₀ values ranging from 7.0-27.1 µM.

Officimalonic acids A-H, lanostane triterpenes from the fruiting bodies of Fomes officinalis

Phytochemical investigation of the methanolic extract of the fruiting bodies of Fomes officinalis led to the isolation of eight 24-methyl-lanostane triterpenes named officimalonic acids A-H, along with one known lanostane triterpene. Their structures were elucidated based on the analysis of spectroscopic data, single-crystal X-ray diffraction, and electronic circular dichroism. Officimalonic acid A represents a previously unknown triterpene type with a 24-methyl-7(8 → 9)abeo-lanostane skeleton, and all of the compounds possessed a malonate half-ester moiety at C-3. Anti-inflammatory assay revealed that officimalonic acids D, E, G, H, and fomitopsin A showed potent inhibitory effects (IC50 = 5.1-8.9 μM) on nitric oxide production in lipopolysaccharide-induced RAW264.7 cells. Officimalonic acids E, G, H showed moderate cytotoxicity against H460, HepG2 and BGC-823 human cell lines.

Two Novel Diphenolic Metabolites from the Inedible Mushroom Thelephora palmata

During the search for bioactive secondary metabolites, thelepalmatins A and B (1 and 2) were isolated from the fresh fruiting bodies of Thelephora palmata, together with four known compounds (3-6). Their structures were elucidated using MS analyses, and extensive 2D-heteronuclear NMR data interpretation. Compounds 3, 4 and 6 showed antimicrobial activities against Staphylococcus aureus and Bacillus subtilis with MIC values of 21.7-70.4 μM.

Six New Lanostane Triterpenoids from the Fruiting Body of Tyromyces Sambuceus and Antiproliferative Activity

During the search for secondary metabolites with antiproliferative activity, six new lanostane triterpenoids, tyrosamic acids A-F (1–6) together with ten known compounds (7–16), were isolated from the fruiting body of Tyromyces sambuceus. Their structures were elucidated using MS analyses, extensive 2D-heteronuclear NMR data interpretation and the structure of 3 was further confirmed by single-crystal X-ray data analyses. All lanostane triterpenoids (1–16) possesses a carboxy group at C-20 position and their strength of antiproliferative activity was affected by the presence or absence of a hydroxy group at C-15 position and at the side chain. Four of the compounds (1, 6, 10, 14) showed antiproliferative activities against human cancer cell lines with IC50 values of 16.8–48.3 μM (HL-60).

Chemical Constituents from the Fruiting Bodies of Hexagonia apiaria and Their Anti-inflammatory Activity

A chemical investigation of the fruiting bodies of Hexagonia apiaria resulted in the identification of nine compounds including five new triterpenoids, hexagonins A-E (1-5), along with four known compounds. The purified constituents were examined for their anti-inflammatory activity. Among the tested compounds, hexatenuin A displayed the most significant inhibition of superoxide anion generation and elastase release. These triterpenoids may have potentials as anti-inflammatory agents.