Silvaglins and related 2,3-secodammarane derivatives - unusual types of triterpenes from Aglaia silvestris

Naturally Occurring Norsteroids and Their Design and Pharmaceutical Application

The main focus of this review is to introduce readers to the fascinating class of lipid molecules known as norsteroids, exploring their distribution across various biotopes and their biological activities. The review provides an in-depth analysis of various modified steroids, including A, B, C, and D-norsteroids, each characterized by distinct structural alterations. These modifications, which range from the removal of specific methyl groups to changes in the steroid core, result in unique molecular architectures that significantly impact their biological activity and therapeutic potential. The discussion on A, B, C, and D-norsteroids sheds light on their unique configurations and how these structural modifications influence their pharmacological properties. The review also presents examples from natural sources that produce a diverse array of steroids with distinct structures, including the aforementioned A, B, C, and D-nor variants. These compounds are sourced from marine organisms like sponges, soft corals, and starfish, as well as terrestrial entities such as plants, fungi, and bacteria. The exploration of these steroids encompasses their biosynthesis, ecological significance, and potential medical applications, highlighting a crucial area of interest in pharmacology and natural product chemistry. The review emphasizes the importance of researching these steroids for drug development, particularly in addressing diseases where conventional medications are inadequate or for conditions lacking sufficient therapeutic options. Examples of norsteroid synthesis are provided to illustrate the practical applications of this research.

Sesquiterpenoids from Meliaceae Family and Their Biological Activities

Sesquiterpenoids, an important class of natural products possessing three isoprene-derived units, are widely distributed across plants and have a variety of biological activities. All sesquiterpenoids are derived from farnesyl pyrophosphate (FPP), a biosynthesis precursor that can form various carbon skeletons. In order to provide a reference for further research and development of these compounds, this review focused on the increasing number of isolated and volatile sesquiterpenoids found to be produced by plants of the Meliaceae family between 1968 and 2023. The related articles were collected from SciFinder, Google Scholar, and PubMed. According to a literature review, several studies were started for more than 55 years on the plant's stem barks, twigs, leaves, flowers, seeds, and pericarps, where approximately 413 sesquiterpenoid compounds from several groups such as eudesmane, aromadendrane, cadinane, guaiane, bisabolane, furanoeremophilane, humulene, germacrane, and oppositane-type were isolated and identified with some minor products. Additionally, the hypothetical route of sesquiterpenoids biosynthesis from this family was identified, and eudesmane-type was reported to be 27% of the total compounds. The antimicrobial, antidiabetic, antioxidant, antiplasmodial, antiviral, and cytotoxic activities of the isolated compounds and major volatile sesquiterpenoids constituent on essential oil were also evaluated. The result showed the fundamental of using the sesquiterpenoid compounds from the Meliaceae family in traditional medicine and the discovery of new drugs.

Naturally occurring dimeric triterpenoids: Occurrence, chemistry and bioactivities

The triterpenes represent one of the most reported subclasses of specialized metabolites from the plant kingdom. They play a key role in the protection of plants and their metabolism in addition to displaying a high structural diversity and large scale of biological activities. The scaffold can undergo several reactions like oxidation or substitution at different positions of the skeleton leading to the formation of several types of compounds. More specifically, triterpene dimer is a small group of compounds found in nature (from plants precisely). Until 2021, the chemical and pharmacological works reported in the literature indicated the identification of 90 natural dimeric triterpenes and 11 synthetic derivatives from 19 plants species and very few of them have been biologically evaluated for their antibacterial, antioxidant, antiproliferative or molluscicide activities. This review aims to compile the literature on the occurrence, chemistry and biological activities of the triterpenoid dimers. To attend this goal, a literature survey has been done in a number of online libraries including Scifinder, PubMed, Web of Science and Google Scholar using keywords terpene, triterpene, dimer, celastroloid without language restriction. This paper provides the easiest access to the information on triterpene dimers for readers and researchers in view to enhancing the continuity of research works on this topic.

Two new triterpenoids from the leaves of Cyclocarya paliurus (Batalin) Iljinskaja

Two previously undescribed triterpenoids (1-2), along with thirteen known compounds (3-15) were isolated from a CHCl₃-soluble extract of the leaves of Cyclocarya paliurus. Their structures were established on the basis of chemical and spectroscopic approaches. These compounds were assessed for their therapeutic effects on diabetic nephropathy (DN)-evoked fibrosis through High-Glucose and transforming growth factor-β1 (TGF-β1) challenged HK-2 cells. Among them, compounds 3, 5 and 8 could remarkedly decrease the level of fibronectin to relieve DN with 27.66 ± 2.77%, 6.09 ± 0.57% and 17.74 ± 5.83% inhibition rate at 10 μM, 10 μM and 1 μM, respectively.

Phytochemistry and biological activities of Aglaia species

Aglaia is the largest genus in the Meliaceae family (also known as Mahagoni in Indonesia), consisting of over 150 species, of which 65 are indigenous to Indonesia. These species spread through the tropical regions, especially Southeast Asia as well as the Nothern part of Australia, and have been used in traditional medicine for the treatment of several diseases. However, preliminary chemical researches commenced in 1965, where dammarane-type triterpenoids, aglaiol was isolated, and the structure was determined by chemical reaction and spectroscopic methods. Several studies have been carried out on the stembark, bark, leaves, seeds and leaves in the last fifty five years, and about 291 metabolites have been isolated from the sesquiterpenoid, diterpenoid, triterpenoid, limonoid, steroid, lignan, and alkaloid groups, as well as flavagline, which known to be the largest. This specifically amounts to 34% of Aglaia species, reported to show cytotoxic and insecticidal potentials, and also the tendency for use as chemical markers for this species. The extracts and compounds obtained from Aglaia species are evaluated for potential biological activities, including cytotoxicity, insecticidal, anti-inflammatory, antifungal, molluscicidal, antituberculosis and antiviral effects. In addition, flavagline (rocaglamide) derivatives have been confirmed to exhibit exceptional cytotoxicity, and are, thus, considered lead compounds for further development. Therefore, the results support the concept of utilizing Aglaia species as a potential source for the production of biologically active compounds.

Cyclopenta[b]benzofuran and Secodammarane Derivatives from the Stems of Aglaia stellatopilosa

Four new 2,3-secodammarane triterpenoids, stellatonins A-D (3-6), together with a new 3,4-secodammarane triterpenoid, stellatonin E (7), and the known silvestrol (1), 5‴-episilvestrol (2), and β-sitosterol, were isolated from a methanol extract of the stems of Aglaia stellatopilosa through bioassay-guided fractionation. The structures of the new compounds were elucidated using spectroscopic and chemical methods. The compounds were evaluated for their cytotoxic activity against three human cancer cell lines and for their antimicrobial activity using a microtiter plate assay against a panel of Gram-positive and Gram-negative bacteria and fungi.

2,3-Seco- and 3,4-seco-tirucallane triterpenoid derivatives from the stems of Aphanamixis grandifolia Blume

Six 2,3-seco-tirucallane triterpenoid derivatives (aphanamgrandins A-F), three 3,4-seco-29-nor-tirucallane triterpenoid derivatives (aphanamgrandins G-I), one 3,4-seco-tirucallane triterpenoid (aphanamgrandin J), two tirucallane triterpenoids [aphanamgrandin K and (23Z)-25-hydroxy-tirucalla-7,23-diene-3-one], and three known triterpenoids were isolated from stems of Aphanamixis grandifolia Blume, and their structures were established by extensive spectroscopic and X-ray crystal diffraction studies.

Triterpenoids from Aglaia abbreviata and their cytotoxic activities

Six new triterpenoids (1-6), along with 10 known compounds, were isolated from the stems of Aglaia abbreviata. The structures of 1-6 were elucidated on the basis of their spectroscopic data. Compounds 1-6 were evaluated for their cytotoxic activities against a small panel of human tumor cell lines.

Isolation and characterization of minor analogues of silvestrol and other constituents from a large-scale re-collection of Aglaia foveolata

Two new minor silvestrol analogues [2'''-episilvestrol (1) and 2''',5'''-diepisilvestrol (2)], together with a new 21-norbaccharane-type triterpene (3), two new 3,4-secodammarane triterpenes (4 and 5), and a new eudesmane sesquiterpene (6), as well as nine known compounds, were isolated from a large-scale re-collection of the CHCl(3)-soluble extract of the stem bark of Aglaia foveolata obtained in Kalimantan, Indonesia. The structures of the new compounds were established by interpretation of their spectroscopic data. All of the isolates were tested for cytotoxicity against HT-29 cells. The new silvestrol analogues, 1 and 2, were considerably less active as cytotoxic agents than silvestrol (7) and episilvestrol (5'''-episilvestrol) (8) against this cell line, showing the importance of the configuration at C-2''' in mediating such activity within this compound class. Several of the compounds isolated were also evaluated in a NF-κB (p65) inhibition assay.

Terpenoid constituents and antifungal activity of Aglaia forbesii seed against phytopathogens

Two new trisnortriterpenoids possessing a γ-lactone ring linked to the D-ring of a 3,4-secodammarane skeleton in a 20R configuration, named isoeichlerialactone (1) and methyl isoeichlerialactone (2), were isolated from the seed of Aglaia forbesii , along with the three dammarane triterpenes, isocabralealactone (3), isoeichlerianic acid (4), and aglinin A (5), the sesquiterpene spathulenol (6), and the widespread sterols β-sitosterol and stigmasterol. Their structures were established based on detailed spectroscopic analysis. Antifungal activity of A. forbesii seed against three phytopathogens, Phytophthora botryosa , P. palmivora , and Rigidoporus microporus , was carried out using the mycelium inhibition test and broth microdilution technique. Superior activity was exhibited by hexane and dichloromethane fractions containing the compounds 1, 4, and 5 as the main components. Subsequent antiphytopathogenic fungi tests proved that compounds 1, 4, and 5 possessed good antifungal activity.

Triterpenoids

This review covers the isolation and structure determination of triterpenoids including squalene derivatives, protostanes, lanostanes, holostanes, cycloartanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, lupanes, oleananes, friedelanes, ursanes, hopanes, isomalabaricanes and saponins; 574 references are cited.