Ursolic Acid Acetate Research Articles

Iso-mukaadial acetate and ursolic acid acetate bind to Plasmodium Falciparum heat shock protein 70: towards targeting parasite protein folding pathway.

Plasmodium falciparum is the most lethal malaria parasite. P. falciparum Hsp70 (PfHsp70) is an essential molecular chaperone (facilitates protein folding) and is deemed a prospective antimalarial drug target. The present study investigates the binding capabilities of select plant derivatives, iso-mukaadial acetate (IMA) and ursolic acid acetate (UAA), against P. falciparum using an in silico docking approach. The interaction between the ligands and PfHsp70 was evaluated using plasmon resonance (SPR) analysis. Molecular docking, binding free energy analysis and molecular dynamics simulations were conducted towards understanding the mechanisms by which the compounds bind to PfHsp70. The molecular docking results revealed ligand flexibilities, conformations and positions of key amino acid residues and protein-ligand interactions as crucial factors accounting for selective inhibition of Hsp70. The simulation results also suggest protein-ligand van der Waals forces as the driving force guiding the interaction of these compounds with PfHsp70. Of the two compounds, UAA and IMA bound to PfHsp70 within the micromolar range based on surface plasmon resonance (SPR) based binding assay. Our findings pave way for future rational design of new selective compounds targeting PfHsp70.

Khuzāma (Lavandula angustifolia Mill.): Pharmacological Action and Therapeutic Uses in Perspective of Unani Medicine: A Review

Lavandula angustifolia Mill., commonly known as lavender, is a highly regarded medicinal herb in Unani Medicine. Its aerial parts, including leaves and flowers, are utilized for their therapeutic properties, and the plant is a common ingredient in cosmetic products. The essential oil derived from lavender is known for its sedative, carminative, anti-depressive, anti-inflammatory, and antimicrobial properties. These pharmacological effects are attributed to various bioactive compounds like betulin, betulinic acid, lactone, 3 beta-formyl ursolic acid, essential oil, glycolic acid, valeric acid, and linalyl acetate. This review aims to comprehensively explore Lavandula angustifolia Mill., covering identification, pharmacological actions, traditional uses, and recent scientific investigations. Utilizing a diverse range of sources, including scientific literature and research studies, the review adopts a comprehensive approach to compile information. The diverse array of bioactive constituents in lavender contributes to its medicinal profile, making it a versatile herbal remedy. Emphasis is placed on documenting and highlighting various pharmacological activities, reinforcing lavender's status as a potent therapeutic agent. Beyond its medicinal applications, the review delves into lavender's historical uses in Unani Medicine and its contemporary role in cosmetic formulations. Lavandula angustifolia Mill. emerges as a herbal powerhouse, offering a holistic approach to health and well-being. This review serves as a valuable resource for practitioners of traditional medicine and modern science alike, bridging the gap between historical wisdom and contemporary research in the realm of herbal medicine.

Ursolic acid acetate and iso-mukaadial acetate bind to Plasmodium falciparum Hsp90, abrogating its chaperone function in vitro

Plasmodium falciparum is the most lethal malaria parasite. Increasing incidences of drug resistance of P. falciparum have prompted the need for discovering new and effective antimalarial compounds with an alternative mode of action. Heat shock protein 90 (PfHsp90) facilitates protein folding and is a promising antimalarial drug target. We have previously reported that iso-mukaadial acetate (IMA) and ursolic acid acetate (UAA) exhibit antimalarial activity. We investigated the abilities of IMA and UAA to bind PfHsp90 by molecular docking and dynamics simulations. The in silico predictions were validated by biochemical assays conducted on recombinant PfHsp90. The interaction between the ligands and PfHsp90 was evaluated using ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared (FTIR), and surface plasmon resonance (SPR) analysis. The results obtained by docking calculations and MD dynamics simulation predicted that UAA and IMA preferentially bound to PfHsp90 via the N-terminal domain, with UAA binding more stable than IMA. UV-vis-based data suggest that PfHsp90 harbors buried aromatic amino acids, which were exposed in the presence of either IMA or UAA. In addition, data obtained using FTIR suggested that IMA and UAA destabilized the secondary structure of PfHsp90. Of the two compounds, UAA bound to PfHsp90 within the micromolar range based on surface plasmon resonance (SPR)-based binding assay. Furthermore, both compounds disrupted the holdase chaperone function of PfHsp90 as the chaperone failed to suppress heat-induced aggregation of the model proteins, malate dehydrogenase (MDH), luciferase, and citrate synthase in vitro. In addition, both compounds lowered the ATPase activity of PfHsp90. The molecular dynamics simulation analysis indicated that the docked complexes were mostly stable for 100 ns, validating the data obtained through the biochemical assays. Altogether, this study expands the repository of antiplasmodial compounds that have PfHsp90 among their possible targets.

Estudio preliminar fitoquímico de fracciones hexánicas de hojas de Eugenia uniflora L. (Myrtaceae)

Fractions from the Hexane Extract (HE) of Eugenia unifloraL. leaves were subjected to various chromatographic systems. Germacrone sesquiterpene and bornyl acetate bicyclic ester were characterized by High Performance Liquid Chromatography coupled to Mass Spectrometry (HPLC-MS) with APCI Mass detector comparing with their homonymous spectrum provided by databases and characteristic fragmentation pathways were proposed. The monoterpene pulegone and the pentacyclic triterpene compound, ursolic acid, were found through High Performance Liquid Chromatography coupled to High Resolution Mass Spectrometry (HPLC -HRMS) by atmospheric pressure ionization (API) and the detector used was mass of Electronic Impact (IE). Both ursolic acid and bornyl acetate are present in other species of the same genus, but not in the species studied.

Ursolic acid as a potential inhibitor of Mycobacterium tuberculosis cytochrome bc1 oxidase-a molecular modelling perspective.

The escalating burden of tuberculosis disease and drastic effects of current medicine has stimulated a search for alternative drugs. A medicinal plant Warburgia salutaris has been reported to possess inhibitory properties against M. tuberculosis. In this study, we apply computational methods to investigate the probability of W. salutaris compounds as potential inhibitors of M. tuberculosis QcrB protein. We performed molecular docking, molecular dynamics simulations, radius of gyration, principal component analysis (PCA), and molecular mechanics-generalized born surface area (MM-GBSA) binding-free energy calculations in explicit solvent to achieve our objective. The results suggested that ursolic acid (UA) and ursolic acid acetate (UAA) could serve as preferred potential inhibitors of mycobacterial QcrB compared to lansoprazole sulphide (LSPZ) and telacebec (Q203)-UA and UAA have a higher binding affinity to QcrB compared to LSPZ and Q203 drugs. UA binding affinity is attributed to hydrogen bond formation with Val120, Arg364 and Arg366, and largely resonated from van der Waals forces resulting from UA interactions with hydrophobic amino acids in its vicinity. UAA binds to the porphyrin ring binding site with higher binding affinity compared to LSPZ. The binding affinity results primarily from van der Waals forces between UAA and hydrophobic residues of QcrB in the porphyrin ring binding site where UAA binds competitively. UA and UAA formed stable complexes with the protein with reduced overall residue mobility, consequently supporting the magnitude of binding affinity of the respective ligands. UAA could potentially compete with the porphyrin ring for the binding site and deprive the mycobacterial cell from oxygen, consequently disturbing mycobacterial oxygen-dependent metabolic processes. Therefore, discovery of a compound that competes with porphyrin ring for the binding site may be useful in QcrB pharmocological studies. UA proved to be a superior compound, although its estimated toxicity profile revealed UA to be hepatotoxic within acceptable parameters. Although preliminary findings of this report still warrant experimental validation, they could serve as a baseline for the development of new anti-tubercular drugs from natural resources that target QcrB.

Iso-mukaadial acetate and ursolic acid acetate inhibit the chaperone activity of Plasmodium falciparum heat shock protein 70-1.

Plasmodium falciparum is the most lethal malaria parasite. The present study investigates the interaction capabilities of select plant derivatives, iso-mukaadial acetate (IMA) and ursolic acid acetate (UAA), against P. falciparum Hsp70-1 (PfHsp70-1) using in vitro approaches. PfHsp70-1 facilitates protein folding in the parasite and is deemed a prospective antimalarial drug target. Recombinant PfHsp70-1 protein was expressed in E. coli BL21 cells and homogeneously purified by affinity chromatography. The interaction between the compounds and PfHsp70-1 was evaluated using malate dehydrogenase (MDH), and luciferase aggregation assay, ATPase activity assay, and Fourier transform infrared (FTIR). PfHsp70-1 prevented the heat-induced aggregation of MDH and luciferase. However, the PfHsp70-1 chaperone role was inhibited by IMA or UAA, leading to both MDH and luciferase's thermal aggregation. The basal ATPase activity of PfHsp70-1 (0.121 nmol/min/mg) was closer to UAA (0.131 nmol/min/mg) (p = 0.0675) at 5 mM compound concentration, suggesting that UAA has no effect on PfHsp70-1 ATPase activity. However, ATPase activity inhibition was similar between IMA (0.068 nmol/min/mg) (p < 0.0001) and polymyxin B (0.083 nmol/min/mg) (p < 0.0001). The lesser the Pi values, the lesser ATP hydrolysis observed due to compound binding to the ATPase domain. FTIR spectra analysis of IMA and UAA resulted in PfHsp70-1 structural alteration for β-sheets shifting the amide I band from 1637 cm-1 to 1639 cm-1, and for α-helix from 1650 cm-1 to 1652 cm-1, therefore depicting secondary structural changes with an increase in secondary structure percentage suggesting that these compounds interact with PfHsp70-1.

Bioassay guided isolation of mosquito biting deterrent compounds from Strumpfia maritima.

In our natural products screening program against mosquitoes, we screened ethanolic extract of Strumpfia maritima Jacq. which showed high biting deterrent activity in Klun and Debboun (K&D) bioassays against Aedes aegypti L. Through bioguided fractionation we isolated six compounds from the active fractions. The extract and pure compounds were evaluated for larvicidal and biting deterrent activity against Aedes aegypti. Ethanolic extract with proportion not biting (PNB) value of 0.8 ± 0.08 provided biting deterrent activity similar to N,N-dimethyl-m-toluamide (DEET) (PNB = 0.9 ± 0.05) against Ae. aegypti. Five out of eight fractions, prepared through bioassay-guided fractionation, showed biting deterrent activity similar to DEET. Six compounds were isolated from active fractions and characterized as squalene, ursolic acid, betulonic acid, cabraleone, ursolic acid acetate, and 27-p-E-coumaroyloxyursolic acid. The biting deterrent activity of ursolic acid acetate (biting deterrence index, BDI = 0.85), cabraleone (BDI = 0.79), and ursolic acid (BDI = 0.78) was similar to DEET against Ae. aegypti. Strumpfia maritima extract did not show larvicidal activity at the highest screening dose of 125 ppm in the larvicidal bioassay. The ethanolic extract and pure compounds showed biting deterrent activity against Ae. aegypti. The high biting deterrent activity of ursolic acid acetate and cabraleone indicated a great potential for these natural compounds to be developed as mosquito repellents. © 2020 Society of Chemical Industry.

Evaluating Iso-Mukaadial Acetate and Ursolic Acid Acetate as Plasmodium falciparum Hypoxanthine-Guanine-Xanthine Phosphoribosyltransferase Inhibitors.

To date, Plasmodium falciparum is one of the most lethal strains of the malaria parasite. P. falciparum lacks the required enzymes to create its own purines via the de novo pathway, thereby making Plasmodium falciparum hypoxanthine-guanine-xanthine phosphoribosyltransferase (PfHGXPT) a crucial enzyme in the malaria life cycle. Recently, studies have described iso-mukaadial acetate and ursolic acid acetate as promising antimalarials. However, the mode of action is still unknown, thus, the current study sought to investigate the selective inhibitory and binding actions of iso-mukaadial acetate and ursolic acid acetate against recombinant PfHGXPT using in-silico and experimental approaches. Recombinant PfHGXPT protein was expressed using E. coli BL21 cells and homogeneously purified by affinity chromatography. Experimentally, iso-mukaadial acetate and ursolic acid acetate, respectively, demonstrated direct inhibitory activity towards PfHGXPT in a dose-dependent manner. The binding affinity of iso-mukaadial acetate and ursolic acid acetate on the PfHGXPT dissociation constant (KD), where it was found that 0.0833 µM and 2.8396 µM, respectively, are indicative of strong binding. The mode of action for the observed antimalarial activity was further established by a molecular docking study. The molecular docking and dynamics simulations show specific interactions and high affinity within the binding pocket of Plasmodium falciparum and human hypoxanthine-guanine phosphoribosyl transferases. The predicted in silico absorption, distribution, metabolism and excretion/toxicity (ADME/T) properties predicted that the iso-mukaadial acetate ligand may follow the criteria for orally active drugs. The theoretical calculation derived from ADME, molecular docking and dynamics provide in-depth information into the structural basis, specific bonding and non-bonding interactions governing the inhibition of malarial. Taken together, these findings provide a basis for the recommendation of iso-mukaadial acetate and ursolic acid acetate as high-affinity ligands and drug candidates against PfHGXPT.

Investigating the effect of radiosensitizer for Ursolic Acid and Kamolonol Acetate ‌ on HCT-116 cell line

PurposeThe aim of this study was evaluating the cytotoxic and radiosensitizing effects of Ursolic Acid (UA) and Kamolonol Acetate (KA) on HCT116 cell line and finally investigating the functional role of NF-κB and CCND1 genes in the radiosensitizing activity of UA and KA. Materials and methodThe cytotoxic effects of UA and KA by MTT assay was evaluated on HCT-116. Clonogenic assay was performed to investigate of radiosensitizing effects of UA and KA on HCT116. To assessment the expression levels of NF-κB and CCND1 genes, real-time PCR method was used. ResultsThe results of MTT assay revealed that UA and KA have cytotoxic effects on HCT116 cell line. According to clonogenic assay, survival fraction of treated cells with UA and KA has been decreased compared to the survival fraction of untreated cells. UA and KA lead to the decrease in the expression level of NF-κB. Synergistic effect of radiosensitizing agents with radiation was only approved for UA and 2 Gy of radiation. ConclusionBased on our study, UA and KA have cytotoxic effects on HCT116 cell line. Furthermore, UA may lead to radiosensitization of human colorectal tumor cells by NF-κB1 and CCND1signaling pathways.

Isolation, structure determination and structure\u2013activity relationship of anti-toxoplasma triterpenoids from Quercus crispula Blume outer bark

Toxoplasma gondii is an intracellular protozoan parasite of which infection can result in serious symptoms for fetuses or people who have weakened immune system. In our effort to discover novel anti-toxoplasma substances from tree barks, only outer bark extract from Quercus crispula Blume (mizunara) was revealed to show potent anti-toxoplasma activity. Isolation of the active principles was performed to identify three pentacyclic triterpenoids, namely 29-norlupane-3,20-dione, oleanolic acid acetate and ursolic acid acetate. These structures were determined by combining a series of spectral data, computational simulation and synthetic approach. All isolated compounds exhibited notable activities at IC50 of 6.8–24.4 μM and high selectivities against the parasite. The structure–activity relationship study conducted to probe key structure(s) indicated that the lack of free hydroxyl group at 3-position highly contributes to both the titer of activity and the selectivity. Moreover, skeleton and functionalities of E-rings were also suggested to affect to the activity. The present study demonstrated not only that the extract from Q. crispula Blume could be a promising source of toxoplasmacidal agent, but also that related extractive triterpenoids can be modified to furnish anti-toxoplasma activity.

Lupane triterpenoids, antioxidant potential and antimicrobial activity of Myrciaria floribunda (H. West ex Willd.) O. Berg.

Chemical composition of the methanol extract of Myrciaria floribunda leaves was investigated. The nor-lupane triterpenoids platanic acid and messagenic I acid were identified, along with other known triterpenoids (betulinic aldehyde, ursolic acid acetate and betulinic acid), a new lupane triterpenoid (2α,6α,30-trihydroxybetulinic acid) and the flavonoids catechin, quercetrin and mirycitrin. The structures were determined by spectroscopic methods (NMR, LC-MS, GC-MS). The major isolated compound was betulinic acid. The methanol extract and 2α,6α,30-trihydroxybetulinic acid were evaluated for their DPPH scavenging potential. The tested triterpenoid was one hundred times more active than betulinic acid, but less active than the extract. Screening for antimicrobial activity showed that the methanol extract was active against Staphylococcus aureus and Escherichia coli, but inactive against Candida albicans and Candida krusei, while 2α,6α,30-trihydroxybetulinic acid was inactive to all tested microorganisms.

Isolation of anti-mycobacterial compounds from Curtisia dentata (Burm.f.) C.A.Sm (Curtisiaceae)

BackgroundTuberculosis is counted amongst the most infectious and lethal illnesses worldwide and remains one of the major threats to human health. The aim of the current study was to isolate and characterize anti-mycobacterial compounds present in Curtisia dentata (Burm.f.) C.A.Sm, a medicinal plant reportedly used in the treatment of tuberculosis, stomach ailments and sexually transmitted infections.MethodsThe bioassay guided principle was followed to isolate the anti-mycobacterial compounds. The crude ethanol extracts of the leaves was partitioned with various solvents four compounds such as β-sitosterol, betulinic acid, ursolic acid and lupeol were successfully isolated. The compounds and their derivatives were evaluated for anti-mycobacterial activity using Microplate Alamar Blue Assay (MABA) against Mycobacterium tuberculosis H37RV (ATCC 27294). Furthermore, the derivatives were investigated for their toxicity against HepG2 and HEK293 using the MTT assay.ResultsThe methanol fraction had the lowest minimum inhibitory concentration (MIC) of 22.2 μg/ml against the selected Mycobacterium strain when compared to other fractions. Ursolic acid acetate (UAA) was the most active compound with MIC value of 3.4 μg/ml. The derivatives had varying degrees of toxicity, but were generally non-toxic to the selected cell lines. Derivatives also exhibited highest selectivity index and offers a higher safety margin.ConclusionsThe derivatives had better antimicrobial activity and low cytotoxic effects compared to isolated compounds. These increased their selectivity. It appears that acetylation of both betulinic acid and ursolic acid increased their activity against the selected Mycobacterium species. The results obtained in this study gives a clear indication that Curtisia dentata may serve as major source of new alternative medicines that may be used to treat TB. Furthermore, there is a need to explore the activity of these tested plant against other pathogenic Mycobacterium species.

A Review of the Endangered Medicinal Plant Blepharispermum subsessile DC: Its Chemistry, Pharmacology and Therapeutic Potential

Blepharispermum subsessile DC. (Asteraceae) is a less explored folklore medicinal plant of India. It is found in the moist deciduous forests of Odisha, Madhya Pradesh, Chhattisgarh, Karnataka and Maharastra etc. It is locally known as Rasnajhadi in Odisha. The whole plant is used as Rasna, a potent Ayurvedic drug. Ethnomedicinally it is used for the treatment of diarrhea, skin diseases, eye troubles, backache and rheumatism, menstrual disorder, common cold and rhinitis. Reports suggest its use as a wormicidal and as tonic. The rhizome has an aromatic odour and is used in havan samagri. Its pharmacological activities include anti-microbial activity, oviposition deterent activity against potato tuber moth, anti-fertility, anti-implantation activity and anti-feedant activity against larvae of Spilarctia obliqua. Many different chromenes were isolated from the aerial parts and rhizomes of B. subsessile such as Desmethyl isoencecalin, 8-methoxy-2, 2-dimethyl chromene, desmethylisoencecalin, 5-hydroxy-6-acetyl-2-hydroxymethyl-2-methyl chromene and (-)-artemesinol. Besides chromenes the plant contains 1.2% essential oil, carvacrol, Ursolic acid acetate and β-sitosterol. The present work aims at presenting a comprehensive of the plant such as its botany, ethnomedicinal uses, chemical constituents, pharmacognostic and pharmacological uses. The information reported in this work contributes scientifically to recognizing the importance of Blepharispermum subsessile as a target in the search for new biotechnological investments.

Triterpenes constituents from male flowers of Eucommia ulmoides

Nine triterpenes compounds were isolated from the male flowers of Eucommia ulmoides by recrystallization and chromatographic techniques over silica gel, Sephadex LH-20, and RP-18 gel. Their chemical structures were identified on the basis of spectral analysis and as 3-oxo-12-en-ursane-28-O-α-L-arabinofuranosyl (1 --> 6) -β-D-glucopyranoside (1), 2α, 3β-dihydroxyurs-12-en-28-oic acid(28 --> 1) -β-D-glucopyranosyl ester (2), ursolic acid (3), α-amyrin (4), uvaol (5), ursolic acid acetate (6), 3-O-acetate oleanoic acid (7), betulinic acid (8), and betulinol (9). Compound 1 was a new compound, and compounds 2, 4-7 were isolated from the Eucommiu genus for the first time. Cytotoxic activity was tested for all the compounds against K562 and HepG2 cells. The results showed that only compound 3, exhibited cytotoxic activity.

Chemical constituents of ethanol extract of leaves and molluscicidal activity of crude extracts from vitex trifolia linn.

Abstract β-sitosterol and two triterpenoids: ursolic acid acetate and platanic acid have been isolated from ethanolic extract of Vitex trifola leaves. β-sitosterol was previously isolated from the leaves, stem and seeds of Vitex trifolia. Ursolic acid acetate has been isolated for the first time in this plant species. Platanic acid has been reported for the first time in Vitex trifolia and even in the family of this plant: Verbenaceae. These compounds were characterized using spectroscopic methods including 1D-1HNMR, 13CNMR, ESIMS and 2D-NMR (HSQC, HMBC, COSY) experiments and confirmed by comparison of their NMR data with those from the literature. A preliminary molluscicidal test for ethanol, chloroform and n-hexane extracts of leaves of Vitex trifolia against Biomphalaria alexandrina adult snails showed that ethanol extract of leaves with LC50 value 26.42 mg/l (27.92 mg/l - 24.99 mg/l) was more effective than n-hexane extract with LC50 value 35.48 mg/l (43.81 mg/l - 28.72mg/l) and chloroform extract with LC50 value 46.77 mg/l (53.59 mg/l - 43.81 mg/l) after 24 h exposure.

Terpenoids, essential oil composition and fatty acids profile, and biological activities of Anatolian Salvia fruticosa Mill.

The hexane and dichloromethane extracts, obtained by re-extraction of the methanol extract of Salvia fruticosa Mill., afforded 7 diterpenoids (carnosol, carnosic acid, carnosic acid 12-methyl ether, rosmadial, isorosmanol, ferruginol, and manool), 4 triterpenoids (\alpha -amyryltetracosanoate, oleanolic acid, ursolic acid, and erythrodiol), a steroid (3-acetylsitosterol), and a flavone (salvigenin). The galls (apples) of the collected plant were separately extracted with hexane to afford fatty acids composed mainly of oleic acid (29\%), palmitoleic acid (29\%), and stearic acid (23.20\%), which exhibited high anticholinesterase activity, particularly against BChE. The essential oil, obtained from the aerial parts of the plant, exhibited high AChE inhibitory activity, consisting of mainly 1,8-cineol (58.89\%). The antioxidant activity according to 6 complementary tests and anticholinesterase potential of the methanol extracts and triterpenoids \alpha-amyryltetracosanoate, oleanolic acid, ursolic acid, and sitosterol acetate were also investigated, and methanol extract exhibited the highest antioxidant and anticholinesterase activity, surpassing the other tested extracts and pure compounds.

A New Ferulic Acid Ester, a New Ellagic Acid Derivative, and Other Constituents from Pachycentria formosana: Effects on Neutrophil Pro‐Inflammatory Responses

A new ferulic acid ester derivative, tetracosane-1,24-diyl di[(Z)-ferulate] (1), and a new ellagic acid derivative, 3,4 : 3',4'-bis(O,O-methylene)ellagic acid (2), have been isolated from leaves and twigs of Pachycentria formosana, together with eight known compounds. Their structures were determined by in-depth spectroscopic and mass-spectrometric analyses. Among the isolated compounds, oleanolic acid (6), ursolic acid acetate (7), and 3-epibetulinic acid (9) exhibited potent inhibition (IC(50) values ≤ 21.8 μM) of O₂(-) generation by human neutrophils in response to N-formyl-L-methionyl-L-leucyl-L-phenylalanine/cytochalasin B (fMLP/CB). In addition, oleanolic acid (6), 3-O-[(E)-feruloyl]ursolic acid (8), 3-epibetulinic acid (9), and lawsonic acid (10) also inhibited fMLP/CB-induced elastase release with IC(50) values ≤ 18.6 μM.

Oxyfunctionalization Products of Terpenoids with Dimethyldioxirane and Their Biological Activity

Oxyfunctionalization of the bioactive terpenoids, ursolic acid acetate (1), oleanolic acid acetate (5), lupeol acetate (12), and kaurenic acid (17), with dimethyldioxirane (DMDO) was investigated. Treatment of the terpenoids with DMDO under mild conditions afforded a variety of oxidation and oxydegradation products to yield naturally occurring and/or novel compounds in one step. After chromatographic separation, the structures of the individual isolated products were determined using spectroscopic methods including several homonuclear (1H-1H) and heteronuclear (1H-13C) shift-correlated 2D-NMR techniques. The inhibitory activity of the terpenoid derivatives against alpha-glucosidase was investigated and compounds 1, 3, 7, and 9 were found to exhibit potent activity.

Chemistry of Fijian Plants. 13. Floribundal, a Nonglycosidic Bisiridoid, and Six Novel Fatty Esters of δ-Amyrin from Scaevola floribunda

Floribundal (1), the first example of a nonglycosidic bisiridoid has been isolated from the heartwood of Scaevola floribunda and its structure and relative stereochemistry determined by NMR spectroscopy and molecular modeling. The aglycon 2 of loganin was also isolated. A mixture of six novel δ-amyrin fatty esters with C20−C30 acid moieties (7−12) were isolated from the bark of S. floribunda and their structures elucidated by NMR and HRMS of the parent compounds and their hydrolysis products. The bark also contains the triterpenes δ-amyrin (13) and δ-amyrin acetate (14), and ursolic acid acetate, betulinic acid, and betulin.

Triterpenoids from Desfontainia spinosa

The leaves and stem of Desfontainia spinosa were found to contain eleven urs-12-ene triterpene compounds. The major compound present was ursolic acid. Four other known compounds were isolated, i.e. ursolic acid acetate, pomolic acid, 23-hydroxytormentic acid and nigaichigoside Fl, its ester glucoside. The other six compounds are novel and have been identified as 24-hydroxytormentic acid, 7α-hydroxytormentic acid, 7α,23-dihydroxytormentic acid and their corresponding ester glucosides. It is unlikely that these compounds contribute to the reputed narcotic properties of this plant.