Structural determination of seven new triterpenoids from Kadsura heteroclita by NMR techniques

Seven new triterpenoids, namely heteroclitalactones G-M (1-7), were isolated from the ethanol extract of the stems of Kadsura heteroclita. Structures of these compounds were characterized by extensive 1D and 2D NMR spectroscopic analyses.     

Highly Oxygenated Triterpenoids and Diterpenoids from Fructus Rubi (Rubus chingii Hu) and Their NF-kappa B Inhibitory Effects

During a phytochemical investigation of the unripe fruits of Rubus chingii Hu (i.e., Fructus Rubi, a traditional Chinese medicine named “Fu-Pen-Zi”), a number of highly oxygenated terpenoids were isolated and characterized. These included nine ursane-type (1, 2, and 4–10), five oleanane-type (3, 11–14), and six cucurbitane-type (15–20) triterpenoids, together with five ent-kaurane-type diterpenoids (21–25). Among them, (4R,5R,8R,9R,10R,14S,17S,18S,19R,20R)-2,19α,23-trihydroxy-3-oxo-urs-1,12-dien-28-oic acid (rubusacid A, 1), (2R*,4S*,5R*,8R*,9R*,10R*,14S*,17S*, 18S*,19R*,20R*)-2α,19α,24-trihydroxy-3-oxo-urs-12-en-28-oic acid (rubusacid B, 2), (5R,8R,9R,10R, 14S,17R,18S,19S)-2,19α-dihydroxy-olean-1,12-dien-28-oic acid (rubusacid C, 3), and (3S,5S,8S,9R, 10S,13R,16R)-3α,16α,17-trihydroxy-ent-kaur-2-one (rubusone, 21) were previously undescribed. Their chemical structures and absolute configurations were elucidated on the basis of spectroscopic data and electronic circular dichroism (ECD) analyses. Compounds 1 and 3 are rare naturally occurring pentacyclic triterpenoids featuring a special α,β-unsaturated keto-enol (diosphenol) unit in ring A. Cucurbitacin B (15), cucurbitacin D (16), and 3α,16α,20(R),25-tetrahydroxy-cucurbita-5,23- dien-2,11,22-trione (17) were found to have remarkable inhibitory effects against NF-κB, with IC₅₀ values of 0.08, 0.61, and 1.60 μM, respectively.     

The Identification of New Triterpenoids in Eucalyptus globulus Wood

Eight polyhydroxy triterpenoid acids, hederagenin, (4α)-23-hydroxybetulinic acid, maslinic acid, corosolic acid, arjunolic acid, asiatic acid, caulophyllogenin, and madecassic acid, with 2, 3, and 4 hydroxyl substituents, were identified and quantified in the dichloromethane extract of Eucalyptus globulus wood by comparing their GC-retention time and mass spectra with standards. Two other triterpenoid acids were tentatively identified by analyzing their mass spectra, as (2α)-2-hydroxybetulinic acid and (2α,4α)-2,23-dihydroxybetulinic acid, with 2 and 3 hydroxyl substituents. Two MS detectors were used, a quadrupole ion trap (QIT) and a quadrupole mass filter (QMF). The EI fragmentation pattern of the trimethylsilylated polyhydroxy structures of these triterpenoid acids is characterized by the sequential loss of the trimethylsilylated hydroxyl groups, most of them by the retro-Diels-Alder (rDA) opening of the C ring with a π-bond at C12-C13. The rDA C-ring opening produces ions at m/z 320 (or 318) and m/z 278 (or 277, 276, 366). Sequential losses of the hydroxyl groups produce ions with m/z from [M - 90] to [M - 90*y], where y is the number of hydroxyl substituents present (from 2 to 4). Moreover, specific cleavage in ring E was observed, passing from m/z 203 to m/z 133 and conducting other major fragments such as m/z 189.     

Lanostane-type triterpenoids from Kadsura coccinea

Systematic phytochemical investigation on the stems of Kadsura coccinea resulted in the isolation of eleven new lanostane-type triterpenoids, named kadcoccinones G–Q (1–11), together with two known structural analogues, kadpolysperin M (12) and abiesatrine D (13). Their structures were characterized on the basis of comprehensive spectroscopic methods, and the absolute configuration of 1 was ascertained by single-crystal X-ray diffraction. Structurally, compounds 1/2, 4/5, and 6/7 were three pairs of C-12 epimers, respectively. Additionally, compounds 1–11 were evaluated for their in vitro cytotoxicity against the human tumor HL-60, SMMC-772, A-549, MCF-7, SW-480, and HeLa cell lines using the MTS viability assay.     

Self‐assembly of Renewable Nano‐sized Triterpenoids

Studies on plant metabolites have gained renewed interest in recent years because these can serve as renewable chemicals for the development of a sustainable society. Among various plant secondary metabolites, terpenoids constitute the major component and triterpenoids are the 30C subset of it. In recent years, triterpenoids have drawn the attention of scientific community due to many of its potential and realized applications in medicine, drug delivery, thermochromic materials, pollutant capture, catalysis, liquid crystals, etc. In this personal review, we have discussed our computational results carried out on sixty representative naturally occurring triterpenoids demonstrating that all the triterpenoids are renewable functional nano‐entities. Study of the self‐assembly of several triterpenoids such as betulin, betulinic acid, oleanolic acid, glycyrrhetinic acid and arjunolic acid and their derivatives in different liquids have also been discussed. Moreover, the utilization of the resulting supramolecular architectures such as vesicles, spheres, flowers and fibrillar networks of nano‐ to micrometer dimensions and gels have also been discussed in the perspective of green, renewable and nanos.     

Nordammarane Triterpenoids from Sanguisorba officinalis

Three new nordammarane triterpenoids, 12β‐O‐acetyl‐3β,22‐dihydroxy‐23,24,25,26,27‐pentanordammarane ( 1 ), 12β,22‐dihydroxy‐3‐oxo‐23,24,25,26,27‐pentanordammarane ( 2 ), and 3β,12β‐dihydroxy‐23,24,25,26,27‐pentanordammarane‐22‐carbaldehyde ( 3 ), were isolated from the EtOH extract of the roots of Sanguisorba officinalis. Structural elucidation of these new triterpenoids on the basis of spectroscopic analyses, including including 1D‐ and 2D‐NMR, and HR‐ESI‐MS, is reported     

Lanostanoids Isolated from Ganoderma lucidum Mycelium Cultured by Submerged Fermentation

Three new lanostane triterpene acids, 3‐O‐acetylganoderic acid B ( 1 ), 8β,9α‐dihydroganoderic acid C ( 3 ), and 3‐O‐acetylganoderic acid K ( 4 ), as well as two new lanostane triterpene acid ethyl esters, ethyl 3‐O‐acetylganoderate B ( 2 ) and ethyl ganoderate J ( 5 ), were isolated and characterized from Ganoderma lucidum mycelia which was cultured by submerged fermentation method. Their structures were elucidated on the basis of spectroscopic methods. In addition, the identification of two known lanostane triterpene acid methyl esters, methyl O‐acetyl ganoderate C and methyl 3,7,11,15,23‐pentaoxo‐lanost‐8‐en‐26‐oate were identified by comparison of the NMR data with those reported in the literature.     

Unusual p‐Coumarates from the Stems of Vaccinium myrtillus

The two previously unreported esters 1 and 2 of pentane‐2,4‐diol and p‐coumaric acid (=3‐(4‐hydroxyphenyl)prop‐2‐enoic acid) along with 13 known compounds including 6 oleanane‐ and ursane‐type triterpenoids were isolated from MeOH extracts of the stems of Vaccinium myrtillus. The structures of the new compounds were assigned as (2S,4R)‐4‐(β‐D ‐glucopyranosyloxy)pentan‐2‐yl (2E)‐p‐coumarate ( 1 ) and its aglycone 2 on the basis of 1D‐ and 2D‐NMR spectroscopic analyses of the isolated and synthesized compounds and molecular modelling experiments. This is the first report on the occurrence of a chiral pentane‐2,4‐diol linker between the phenol‐derived acid and a glycoside part in natural products.     

Distribution of Triterpenoids and Steroids in Developing Rugosa Rose (Rosa rugosa Thunb.) Accessory Fruit

Triterpenoids and steroids are considered to be important for the fruit quality and health-promoting properties for the consumers. The aim of the study was the determination of the changes in triterpenoid and steroid biosynthesis and the accumulation in hypanthium and achenes of rugosa rose (Rosa rugosa Thunb.) hip during fruit development and ripening at three different phenological stages (young fruits, fully developed unripe fruits, and matured fruits). Triterpenoids and steroids were also determined in the peel and the pulp of the matured hips. The obtained results indicated that the distribution of the analyzed compounds in different fruit tissues is a selective process. The increased rate of hydroxylation of triterpenoids, the deposition of hydroxylated acids in fruit surface layer, and the continuous biosynthesis of phytosterols in achenes versus its gradual repression in hypanthium accompanied by the accumulation of their biosynthetic intermediates and ketone derivatives seem to be characteristic metabolic features of maturation of rugosa rose accessory fruit. These observations, apart from providing the important data on metabolic modifications occurring in developing fruits, might have a practical application in defining fruit parts, particularly rich in bioactive constituents, to enable the development of novel functional products.     

Triterpenoids and lignans from the stems of Schisandra glaucescens

Two new triterpenoids, 24(E)-3α,12α-dihydroxyl-lanost-9(11),24-dien-26-oid acid (1) and 3,4-seco-24(Z)-6α,7β-dihydroxyl-cycloart-4(28),24-dien-3,26-dioic-3-methyl ester (2), and ten known ones (3–12), together with eight lignans (13–20), were isolated from the stems of Schisandra glaucescens. Their structures were established on the basis of extensive spectroscopic analyses. Compounds 1–3, 5–7, 9, 11–13 and 15–18 were isolated from this species for the first time. 1 and 2 were evaluated for their in vitro cytotoxicities against the mouse cancer B16 cell line, human cancer HepG2 and MCF7 cell lines by MTT assay.