The Genus Walsura: A Rich Resource of Bioactive Limonoids, Triterpenoids, and Other Types of Compounds

Medicinal plants of the genus Walsura (family Meliaceae) are native to tropical zones of a number of Asian countries, and have been used in systems of folk medicine. Several original research articles on Walsura species are available, but an overview highlighting the phytochemical and biological aspects of the compounds isolated to date is so far absent. Since the 1970s, phytochemical investigations on the genus Walsura have been undertaken, and more than 220 compounds from ten species have been identified. Natural products from Walsura species that have received the most attention are limonoids (114 compounds) and triterpenoids (72 compounds). Walsura limonoids have been characterized structurally as having diverse skeletons and more than 100 such compounds are new to the literature, while dammaranes, tirucallanes, and apotirucallanes are the main triterpenoid types from this genus. Other Walsura constituents comprise sesquiterpenoids, flavonoids, sterols, lignans, xanthones, and anthraquinones. Walsura species constituents have also been studied in natural product drug discovery screening programs. Many in vitro biological and some in vivo pharmacological investigations have been carried out on Walsura species isolated compounds. Walsura components display properties such as cancer cell cytotoxicity, antimicrobial, antidiabetes, anti-inflammatory, antioxidant, antifeedant, antifertility, ichthyotoxic, and neuroprotection activities.

Pentacyclic and hexacyclic cucurbitacins from Elaeocarpuspetiolatus

Four undescribed cucurbitacins, designated as petiolaticins A-D, and four known cucurbitacins were isolated from the bark and leaves of Elaeocarpus petiolatus (Jack) Wall. Their chemical structures were elucidated based on detailed analyses of the NMR and MS data. The absolute configuration of petiolaticin A was also determined by X-ray diffraction analysis. Petiolaticin A represents a cucurbitacin derivative incorporating a 3,4-epoxyfuranyl-bearing side chain, while petiolaticin B possesses a furopyranyl unit fused to the tetracyclic cucurbitane core structure. Petiolaticins A, B, and D were evaluated in vitro against a panel of human breast, pancreatic, and colorectal cancer cell lines. Petiolaticin A exhibited the greatest cytotoxicity against the MDA-MB-468, MDA-MB-231, MCF-7, and SW48 cell lines (IC₅₀ 7.4, 9.2, 9.3, and 4.6 μM, respectively). Additionally, petiolaticin D, 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one, and 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one 3-O-β-_D-glucopyranoside were tested for their ability to inhibit cell entry of a pseudotyped virus bearing the hemagglutinin envelope protein of a highly pathogenic avian influenza virus. Petiolaticin D showed the highest inhibition (44.3%), followed by 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one (21.0%), and 16α,23α-epoxy-3β,20β-dihydroxy-10αH,23βH-cucurbit-5,24-dien-11-one 3-O-β-_D-glucopyranoside showed limited inhibition (9.0%). These preliminary biological assays have demonstrated that petiolaticins A and D possess anticancer and antiviral properties, respectively, which warrant for further investigations.

A review of alpha-glucosidase inhibitors from plants as potential candidates for the treatment of type-2 diabetes

Diabetes mellitus is a multifactorial global health disorder that is rising at an alarming rate. Cardiovascular diseases, kidney damage and neuropathy are the main cause of high mortality rates among individuals with diabetes. One effective therapeutic approach for controlling hyperglycemia associated with type-2 diabetes is to target alpha-amylase and alpha-glucosidase, enzymes that catalyzes starch hydrolysis in the intestine. At present, approved inhibitors for these enzymes are restricted to acarbose, miglitol and voglibose. Although these inhibitors retard glucose absorption, undesirable gastrointestinal side effects impede their application. Therefore, research efforts continue to seek novel inhibitors with improved efficacy and minimal side effects. Natural products of plant origin have been a valuable source of therapeutic agents with lesser toxicity and side effects. The anti-diabetic potential through alpha-glucosidase inhibition of plant-derived molecules are summarized in this review. Eight molecules (Taxumariene F, Akebonoic acid, Morusin, Rhaponticin, Procyanidin A2, Alaternin, Mulberrofuran K and Psoralidin) were selected as promising drug candidates and their pharmacokinetic properties and toxicity were discussed where available.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11101-021-09773-1.

Exploring the therapeutic nature of limonoids and triterpenoids against SARS-CoV-2 by targeting nsp13, nsp14, and nsp15 through molecular docking and dynamic simulations

Background and aim

The ongoing global pandemic due to SARS-CoV-2 caused a medical emergency. Since December 2019, the COVID-19 disease is spread across the globe through physical contact and respiratory droplets. Coronavirus caused a severe effect on the human immune system where some of the non-structural proteins (nsp) are involved in virus-mediated immune response and pathogenesis. To suppress the viral RNA replication mechanism and immune-mediated responses, we aimed to identify limonoids and triterpenoids as antagonists by targeting helicases (nsp13), exonuclease (nsp14), and endoribonuclease (nsp15) of SARS-CoV-2 as therapeutic proteins.

Experimental procedure

In silico molecular docking and drug-likeness of a library of 369 phytochemicals from limonoids and triterpenoids were performed to screen the potential hits that binds effectively at the active site of the proteins target. In addition, the molecular dynamics simulations of the proteins and their complexes with the potential hits were performed for 100 ns by using GROMACS.

Results and conclusion

The potential compounds 26-deoxyactein and 25-O-anhydrocimigenol 3-O-beta-d-xylopyranoside posing strong interactions with a minimum binding energy of -10.1 and -9.5 kcal/mol, respectively and sustained close contact with nsp13 for 100 ns. The nsp14 replication fork activity was hindered by the tomentosolic acid, timosaponin A-I, and shizukaol A with the binding affinity score of -9.2, -9.2, and -9.0 kcal/mol, respectively. The nsp15 endoribonuclease catalytic residues were inhibited potentially by limonin, 25-O-anhydrocimigenol 3-O-alpha-l-arabinopyranoside, and asperagenin posing strong binding affinity scores of -9.0, -8.8, and -8.7 kcal/mol, respectively. Computationally predicted potential phytochemicals for SARS-CoV-2 are known to possess various medicinal properties.

The restructuring of grape berry waxes by calcium changes the surface microbiota

The observation that exogenous Ca shifted the polyphenolic profile of grape berries and conferred a glossy appearance to mature fruits led us to hypothesize that the composition of grape berry waxes and thus surface microbiota are modified. In two cultivars sharing the same microclimate, the triterpenoid and steroid profile of berry cuticle was characterized by a targeted metabolomic approach, and surface microbial communities were surveyed by ITS and 16S metabarcoding. Results showed that Ca strongly decreased the levels of oleanolic acid, while steroids and neutral triterpenoids were affected in a cultivar-dependent manner. A total of 174 fungi and 192 bacteria OTUs were identified, with Dothideomycetes, Leotiomycetes, Alphaproteobacteria and Gammaproteobacteria comprising the most abundant classes. Ca decreased fungi biodiversity, favoring the growth of Basidiomycetes, and shifting fungi-bacteria relationships. Metabolite-microbiota networks revealed a tight relationship between microbial communities and triterpenoid components of fruit waxes, mainly stigmasterol, tremulone and oleanolic acid.

Secoiridoids and triterpenoids from the traditional Tibetan medicine Gentiana veitchiorum and their immunosuppressive activity

Two undescribed secoiridoids (dehydroxyl-swerimilegenin H and 9-oxo-swerimuslactone A) with eight known ones, and two undescribed triterpenoids [28-O-(3,4-dihydroxyl-benzyl)-lupeol and 17-hydroperoxide-28-norurs-12-en-3-one] with seven known ones, were isolated from the aerial parts of Gentiana veitchiorum, a traditional Tibetan medicine. The structures of these compounds were elucidated by detailed spectroscopic analyses (including 1D and 2D NMR, HRMS, IR, and specific rotation) and comparison with structurally related known compounds. The isolates were selected to evaluate for their immunosuppressive activity via inhibiting the proliferation of T cells and cytokine IFN-γ production in T cells. Among them, 28-O-(3,4-dihydroxyl-benzyl)-lupeol exhibited significant effect by inhibiting the proliferation of T cells (IC₅₀, 20.08 μM) and T cell IFN-γ production (IC₅₀, 7.29 μM).

Effect of ultrasonication on the metabolome and transcriptome profile changes in the fermentation of Ganoderma lucidum

Development of an efficient liquid fermentation method is helpful for food and pharmaceutical applications. This study investigated the effect of ultrasonication on the liquid fermentation of Ganoderma lucidum, a popular edible and medical fungi. Significant changes at both metabolic and transcriptional levels in mycelia were induced by ultrasound treatment. Compared with the control, 857 differential metabolites were identified (578 up- and 279 down-regulated metabolites), with more metabolites biosynthesis after sonication; 569 differentially expressed genes (DEGs) (267 up- and 302 down-) and 932 DEGs (378 up- and 554 down-) were identified in ultrasound-treated samples with recovery time of 0.5 and 3 h, respectively. Furthermore, 334 DEGs were continuously induced within the recovery time of 3 h, indicating the lasting influence of sonication on mycelia. The DEGs and differential metabolites were mainly involved in pathways of carbohydrate, energy metabolism, amino acids, terpenoids biosynthesis and metabolism and membrane transport, suggesting that ultrasound induced multifaceted effects on primary and secondary metabolism. Ultrasonication enhanced the triterpenoids production of G. lucidum (34.96 %) by up-regulating the expression of terpenoids synthase genes. This study shows that the application of ultrasound in liquid fermentation of G. lucidum is an efficient approach to produce more metabolites.

Triterpenoids and meroterpenoids with α-glucosidase inhibitory activities from the fruiting bodies of Ganoderma australe

Macrofungi Ganoderma is a valuable medicinal fungus resource for human health and longevity in China. In this study, ten undescribed compounds including seven lostane-type triterpenoids, ganodaustralic acids A ∼ G (1-7), one pair of meroterpenoid enantiomers, (-)-6'-O-ethyllingzhiol (8) and (+)-6'-O-ethyllingzhiol (9), and one polyhydroxylated sterol, 3-O-acetyl-fomentarol C (10), together with eight known compounds (11-18), were isolated from the fruiting bodies of Ganoderma australe. The structures of the new compounds were elucidated by extensive spectroscopic analysis as well as NMR and electronic circular dichroism (ECD) calculations. Compounds 4, 8, 9, and 12 showed significant α-glucosidase inhibitory activities with IC₅₀ values in the range of 4.1-11.7 μM, which were superior to that of positive control acarbose (213 μM). Only compound 7 exhibited weak cytotoxicity against SGC-7901 cells.

Synthesis of erythrodiol C-ring derivatives and their activity against Chlamydia trachomatis

To develop new potential agents against Chlamydia trachomatis among oleanane type triterpenoids the synthesis, spectral and X-ray analysis as well as antimicrobial screening of C-12 oxygen and nitrogen derivatives of erythrodiol is presented. The reduction of methyl 3β-acetoxy-12-oxo-oleanoate with LiAlH₄ led to isomeric erythrodiol 12β- and 12α-hydroxy-derivatives, their stereochemistry with respect to the position of hydroxyl-group at C-12 was determined based on the multiplets splitting patterns, the magnitude of the spin-spin interaction, and NOESY interactions. Methyl 3β-acetoxy-12-oxo-oleanoate was transformed to 12E-hydroxyimino- and 12E-methoxyimino-derivatives by the interaction with NH₂OH∙HCl or CH₃ONH₂∙HCl, respectively. By Beckmann rearrangement with SOCl₂ in dioxane 12E-oxime was converted to C-lactame and its following reduction with LiAlH₄ in THF or dioxane led to erythrodiol C-azepanone or C-azepane derivatives. The structure 3-O,12-N-bis-acetyl-derivative of C-azepane-erythrodiol was confirmed by the single crystal X-ray analysis. Erythrodiol 12β-hydroxy- and C-azepane derivatives were found to be lead compounds with significant activity against C. trachomatis with MIC 1.56 and 3.125 μg/mL. Molecular docking was employed to suggest potential binding interaction, the tested compounds are likely to act as Cdu1 protein inhibitors while 12β-hydroxy-erythrodiol exhibited the highest affinity towards this respective target protein. These results indicated that C-ring oxygen and nitrogen erythrodiol derivatives might be considered for further research in the design of antibacterial agents against Chlamydia trachomatis.

The genus Schefflera: A review of traditional uses, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Schefflera is the largest genus in the family Araliaceae, which contains 602 known species indigenous to Asia, Africa, and the southwest Pacific region, several of which are used in traditional medicine.

AIM OF THE REVIEW

The review discusses current knowledge of the traditional uses, phytochemistry, and biological activities of Schefflera species, to assess the medicinal potential of this genus.

MATERIALS AND METHODS

The literature were explored using the keyword "Schefflera" in SciFinder®, Google Scholar®, and PubMed® databases. The taxonomy of all reported plants was authenticated using "The Plant List". Additional data on traditional uses was obtained from secondary references including books and online resources.

RESULTS

Fourteen species were documented as traditional medicines in China, India, Vietnam, Thailand, and Indonesia, specifically to manage rheumatism, pain, and trauma. Other species are used in the treatment of liver disorders, skin conditions, respiratory infections, cancer, diarrhea, malaria, paralysis, and many other conditions. The main phytochemical constituents identified were triterpenoids and saponins, with sesquiterpenes, phenylpropanoids, and lignans. Pharmacological properties of extracts and pure isolated compounds included analgesic, anti-inflammatory, anticancer, hypoglycemic, antimicrobial, hepatoprotective, neuroprotective, antimalarial, and antiallergic effects.

CONCLUSION

The reported biological activities of Schefflera species support their traditional uses, although the available data, even for medicinal species, was limited. Reports of chemical constituents or biological activities could be found for only about 20 species, but suggest that further investigation of efficacy and safety of the largely unexplored genus Schefflera is necessary.

Ultra Performance Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry (UPLC-Q-TOF-MS)-based metabolomic analysis of mycelial biomass of three Ganoderma isolates from the Lower Volta River Basin of Ghana

In this work, we sought to determine the differences and/or similarities in the metabolite composition of the mycelial biomass of three ganoderma isolates (Ganoderma LVRB-1, Ganoderma LVRB-9 and Ganoderma LVRB-17) from the Lower Volta River Basin of Ghana. The cultured mycelial mass of the three isolates were subjected to DNA sequencing. BLASTn searches of the internal transcribed spacer. (ITS) sequences of the isolates were conducted in the GenBank and the data obtained subjected to ITS phylogenetic analysis. Thereafter, extracts of the cultured mycelial biomass of the three isolates were subjected to untargeted ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS)-based metabolomic analysis. A cursory examination of the total ion chromatograms of the isolates gave evidence of the differential levels of the metabolites present. Further analysis of the metabolomic data using multivariate analysis better captured these marked differences in terms of the presence and/or levels of the metabolites. Finally, four lanostane triterpenoids, namely ganoderic acid C6, ganoderenic acid A, Ganoderenic acid D and ganoderic acid G, together with two annotated compounds (ganoderic acids K and AM1) were detected in the mycelia biomass of the three ganoderma isolates from the Lower Volta River Basin of Ghana. The results provide the first ever metabolomic data on the chemical constituents of the mycelial biomass of ganoderma isolates from the Lower Volta River Basin of Ghana.

Euphorfistrines A-G, cytotoxic and AChE inhibiting triterpenoids from the roots of Euphorbia fischeriana

Seven new triterpenoids including two cycloartanes (1-2), a lanostane (3), a tirucallane (4), a dammarane (5), an ursane (6), and an oleanane (7), along with nineteen known triterpenoids (8-26), have been obtained from the roots of Euphorbia fischeriana. Their structures were established by NMR, HRESIMS, single-crystal X-ray diffraction analysis, Mosher's method, NMR calculations, ECD analysis, and comparison with structurally related known analogues. Among them, compounds 1 and 8 were a pair of cycloartane-type triterpenoids epimers. Our bioassays have established that compounds 1-5 and 10 displayed moderate cytotoxic effects, and the structure-activity relationships of cycloartane-type triterpenoids (CTTs) were further examined. Notably, some triterpenoids displayed moderate inhibitory effects against AChE by an in vitro screened experiment. Triterpenoid 7 (Euphorfistrine G, ETG) displayed the potent inhibitory effect with IC₅₀ = 2.45 and K_i = 2.30 μM (inhibition kinetic). And, in silico docking analyses have been performed to investigate the inhibitory mechanism of compound 7.

Triterpenoids with modified A-ring as modulators of P-gp-dependent drug-resistance in cancer cells

Semi-synthetic A-cycle modified triterpenic derivatives with A-cycle condensed with a heterocyclic fragment (compound 1) and fragmented A-ring (compound 2) were tested for cytotoxicity against several tumor cell cultures and doxorubicin (Dox)-resistant cell lines. The equal cytotoxicity of the tested compounds to the parental tumor cell lines (HBL-100, K562) and their resistant subclones (HBL-100/Dox, K562/i-S9) was revealed. The overexpression of ABCB1 (MDR1) gene and P-glycoprotein (P-gp) was confirmed for both resistant subclones of tumor cells. Compounds 1 and 2 were shown to inhibit the ABC-transporter gene expression (MDR1, MRP, MVP, and BCRP) and the transport of well-known P-gp substrate Rhodamine 123 from resistant cells. The docking of triterpenoids 1 and 2 into the drug binding site of P-gp revealed a similarity between the conformation of the tested triterpenoids and that of classical inhibitor verapamil, thus assuming these compounds to be more likely the inhibitors than the substrates of P-gp. Any tested triterpenic derivatives, when combined at non-toxic concentrations with doxorubicin, improved cytotoxic effect of the therapeutic drug against resistant subclones of tumor cells.

De novo transcriptome analysis and identification of candidate genes associated with triterpenoid biosynthesis in Trichosanthes cucumerina L

De novo transcriptome analysis from callus, leaf, and fruit of Trichosanthes cucumerina L. for the identification of genes associated with triterpenoid biosynthesis, especially bryonolic acid and cucurbitacin B. Trichosanthes cucumerina L. (TC) has been used as a medicinal plant in Thailand with various potential functions. Two major triterpenoids found in this plant, bryonolic acid and cucurbitacin B, are receiving increased attention for their activities. Here, we provide TC transcriptome data to identify genes involved in the triterpenoid biosynthetic pathway through callus, where was previously suggested as a novel source for bryonolic acid production as opposed to leaf and fruit. A de novo assembly of approximately 290-thousand transcripts generated from these tissues led to two putative oxidosqualene cyclases: isomultiflorenol synthase (IMS) and cucurbitadienol synthase (CBS). TcIMS and TcCBS, genes that encode substrates for two characteristic triterpenoids in cucurbitaceous plants, were identified as isomultiflorenol synthase and cucurbitadienol synthase, respectively. These two genes were functionally characterised in mutant yeast Gil77 systems, which led to the productions of isomultiflorenol and cucurbitadienol. Moreover, the callus-specific gene expression profiles were also presented. These obtained information showed candidate cytochrome P450s with predicted full-length sequences, which were most likely associated with triterpenoid biosynthesis, especially bryonolic acid. Our study provides useful information and a valuable reference for the further studies on cucurbitaceous triterpenoids.

Isolation and Structural Elucidation of Novel Antidiabetic Compounds from Leaves of Momordica balsamina Linn and Leptadenia hastata (Pers) Decne

The antihyperglycemic effect of the polyherbal combination of the leaves of Momordica balsamina Linn (MB) and Leptadenia hastata (pers) Decne (LH) have been reported in our previous study in addition to its documented dietary usages. However, the bioactive principles are yet to be fully elucidated. In the present study, bioactive antidiabetic compounds from the leaf extracts of Momordica balsamina Linn and Leptadenia hastata (pers) Decne were isolated and characterized. The plant leaves were fractionated with solvents in ascending order of polarity (hexane-chloroform-ethylacetate-methanol) using microwave assisted extraction method. The ethylacetate (MBE) and methanolic (LHM) leaf extracts of MB and LH, having the highest antihyperglycemic effects were purified by column chromatography and preparative thin layer chromatography. The antihyperglycemic activity of the isolated compounds was evaluated in streptozotocin (STZ)-induced diabetic rats and the structures of the most bioactive compounds were elucidated by ¹H and ¹³C Nuclear Magnetic Resonance (NMR) spectroscopy in comparison with reported literature. A pentacyclic triterpenoid (H3) and an isoflavone (LH2b) isolated from MBE and LHM with significant (p < 0.05) antihyperglycemic effects were identified as betulinic acid and 5-methyl genistein respectively. Our study isolated for the first time a triterpenoid and an isoflavone with potential antidiabetic effects from these indigenous antidiabetic plants. This further validates the traditional multi-therapeutic usage of the combination for the management of Diabetes Mellitus (DM) and its complications.

Expression Analysis of Lanosterol synthase Gene in Dynamic Accumulation of Triterpenoids in Sanghuangporus baumii

BACKGROUND

Sanghuangporus baumii is a traditional Chinese medicine with anti-cancer, anti-tumor, and anti-inflammatory effects. Triterpenoids are one of the main medicinal ingredients found in S. baumii. However, the dynamic changes of triterpenoids content and its molecular regulation mechanism are still unclear.

OBJECTIVE

Some studies have shown that Lanosterol synthase (LS) is a key enzyme involved in the mevalonate pathway (MVA pathway) to produce lanosterol, which is a precursor for synthesizing S. baumii triterpenoids. Therefore, the study of LS gene and expression characteristics can provide clues for the further study of triterpenoids synthesis.

METHODS

The PCR, RACE PCR, RT-PCR, seamless cloning and prokaryotic expression technology were used to research the gene characteristic and dynamic changes of LS transcription level.

RESULTS

The S. baumii LS sequence included a 5'-untranslated region (129 bp), a 3'-untranslated region (87 bp), and an open reading frame (2,229 bp) encoding 734 amino acids. The S. baumii LS protein was expressed in E. coli BL21 (DE3). The transcription start site of the S. baumii LS promoter sequence ranged from 1 740 bp to 1790 bp. The LS promoter contained 12 CAAT-boxes, 5 ABREs, 6 G-Boxes, 6 CGTCA-motifs, and so on. The LS transcription levels were the highest on day 11 in mycelia (1.6-fold), and the triterpenoids content also gradually increased. The transcription levels began to decrease on day 13, but the triterpenoids content still increased.

CONCLUSION

The S. baumii LS was cloned and characterized to help to understand the mechanism of triterpenoids synthesis. In addition, we studied the relationship between LS transcription level and triterpenoid dynamic accumulation, and we found that they had a certain correlation.

Mildly toxic shrubs as indicators of goats herbivory give information for the management of natural landscapes on Mediterranean islands

Herbivory of insular plant communities by introduced animals has been widely studied for decades. Though their diet mainly includes palatable and highly nutritive species, goats will also eat plants that are toxic to other animals. Thus, severe affection of toxic species may indicate high herbivore pressure or a low quality of vegetative food. To evaluate whether herbivory damage to low-palatability shrubs could give us information about feral goat pressure on vegetation, we assessed the predation impact of feral goats on the shrub Euphorbia dendroides (Euphorbiaceae) on Mallorca Island (Spain). We aimed to investigate whether goats consume juvenile E. dendroides and affect their population structure and determine if the plants increase the concentrations of toxic compounds as an adaptation to herbivory. Overall, two experimental plots and analysis of eleven natural populations indicated E. dendroides is affected by ungulates and that the population structure change with the presence of feral goats. Euphorbia dendroides could be used as an ecological indicator to determine the extent of ungulate damage to vegetation or indicate poor food availability, and thus inform the maintenance of optimal animal populations. Depending on the management objective for the territory, E. dendroides could be used as an ecological indicator to determine the extent of ungulate damage to vegetation or indicate poor food availability for animals, and thus inform the maintenance of optimal animal populations.

Analysis of composition, morphology, and biosynthesis of cuticular wax in wild type bilberry (Vaccinium myrtillus L.) and its glossy mutant

In this study, cuticular wax load, its chemical composition, and biosynthesis, was studied during development of wild type (WT) bilberry fruit and its natural glossy type (GT) mutant. GT fruit cuticular wax load was comparable with WT fruits. In both, the proportion of triterpenoids decreased during fruit development concomitant with increasing proportions of total aliphatic compounds. In GT fruit, a higher proportion of triterpenoids in cuticular wax was accompanied by a lower proportion of fatty acids and ketones compared to WT fruit as well as lower density of crystalloid structures on berry surfaces. Our results suggest that the glossy phenotype could be caused by the absence of rod-like structures in GT fruit associated with reduction in proportions of ketones and fatty acids in the cuticular wax. Especially CER26-like, FAR2, CER3-like, LTP, MIXTA, and BAS genes showed fruit skin preferential expression patterns indicating their role in cuticular wax biosynthesis and secretion.

Inhibitory effect of triterpenoids from the mushroom Inonotus obliquus against α-glucosidase and their interaction: Inhibition kinetics and molecular stimulations

Bioassay-guided fractionation led to the isolation of a series of triterpenoids (1-46) including 12 new ones (1-12) from the mushroom Inonotus obliquus. The structures of all the compounds were elucidated by spectroscopic analysis as well as by comparison with literature data. Triterpenoids 1-3, 6, 7, 16, 24, 25, 27, 38, 43, 44 and 46 showed strong α-glucosidase inhibition, with IC₅₀ values from 11.5 to 81.8 μM. Their structure-activity relationships were discussed. Inonotusol F (24) showed the strongest inhibitory activity and it presented noncompetitive inhibition against α-glucosidase. Molecular docking and molecular dynamics stimulation further demonstrated that GLU302 and PHE298 were key amino acids for the inhibition of inonotusol F (24) towards α-glucosidase. This study indicates the vital role of triterpenoids in explaining hypoglycemic effect of Inonotus obliquus and provides important evidence for further development and utilization of this mushroom.

Amazonian medicinal smokes: Chemical analysis of Burseraceae pitch (breu) oleoresin smokes and insights into their use on headache

ETHNOPHARMACOLOGICAL RELEVANCE

In Latin American Traditional Medicine, the use of Burseraceae oleoresins for headache relief is widespread. In the quilombola (maroon) communities of the municipality of Oriximiná, Pará State, Brazil, Burseraceae oleoresins are burned as incenses to treat headache; an effect attained by inhaling the smokes.

AIM OF THE STUDY

This study was designed to investigate the scientific rationale behind the use of Burseraceae pitch oleoresin smokes on headache by identifying its chemical constituents and discussing whether they could be beneficial for headache treatment.

MATERIALS AND METHODS

Two samples of pitch oleoresins were purchased from Amazonian public markets; one of them marketed as "breu preto" (black pitch), and the other as "breu branco" (white pitch). The smoke headspaces produced upon burning these oleoresins were collected and analysed by GC-MS. For comparative purposes, the triterpenoid fingerprints of the oleoresins' dichloromethane extracts and profiles of the essential oils were also obtained by GC-MS - and GC-FID, in the case of the essential oils.

RESULTS

A total of 32 compounds were detected in black and white pitch oleoresin smokes. All smoke headspaces of the pitch oleoresins shared the presence of volatile terpenoids (e.g., α-terpineol) and triterpenoids (e.g., α-amyrin, β-amyrin, α-amyrone, and β-amyrone). These compounds were also present in the crude resins and could potentially be responsible for anti-inflammatory, antinociceptive and analgesic effects on headache.

CONCLUSIONS

The pharmacological data on the terpenoids detected in the Burseraceae pitch smokes strongly support their traditional use for headache, but their actual effects upon inhalation have yet to be determined.

Molecular cloning and functional characterization of multiple ApOSCs from Andrographis paniculata

Triterpenoids have been described in Andrographis paniculata. Oleanolic acid exhibits high biological activity and is widely used in the clinic, and β-sitosterol not only has good biological activity but also plays an important physiological role in plants. However, analysis of the biosynthetic pathway of triterpenoids in Andrographis paniculata has not been reported. Here, we provide the first report of the isolation and identification of nine 2, 3-oxidosqualene cyclases (ApOSC3 to ApOSC11) from A. paniculata. The results showed that ApOSC4 represented a monofunctional synthase that could convert 2, 3-oxidosqualene to β-amyrin. ApOSC5 as a bifunctional 2, 3-oxidosqualene cyclases, could transfer 2, 3-oxidosqualene to β-amyrin and α-amyrin. ApOSC6 to ApOSC8 composed the multifunctional 2, 3-oxidosqualene cyclases that could convert 2, 3-oxidosqualene to β-amyrin, α-amyrin and one or two undetermined triterpenoids. This study provides a better understanding of the biosynthetic pathway of triterpenoids in A. paniculata, and the discovery of multifunctional 2, 3-oxidosqualene cyclases ApOSC5 to ApOSC8 of the facilitates knowledge of the compounds diversity in A. paniculata.

Multifunctional inhibitors of SARS-CoV-2 by MM/PBSA, essential dynamics, and molecular dynamic investigations

The ongoing COVID-19 pandemic demands a novel approach to combat and identify potential therapeutic targets. The SARS-CoV-2 infection causes a hyperimmune response followed by a spectrum of diseases. Limonoids are a class of triterpenoids known to prevent the release of IL-6, IL-15, IL-1α, IL-1β via TNF and are also known to modulate PI3K/Akt/GSK-3β, JNK1/2, MAPKp38, ERK1/2, and PI3K/Akt/mTOR signaling pathways and could help to avoid viral infection, persistence, and pathogenesis. The present study employs a computational approach of virtual screening and molecular dynamic (MD) simulations of such compounds against RNA-dependent RNA polymerase (RdRp), Main protease (Mpro), and Papain-like protease (PLpro) of SARS-CoV-2. MD simulation, Molecular Mechanics Poisson-Boltzmann Surface Area (MM/PBSA), and Essential dynamics revealed that the macromolecule-ligand complexes are stable with very low free energy of binding. Such compounds that could modulate both host responses and inhibit viral machinery could be beneficial in effectively controlling the global pandemic.

The Introduction of Hydrazone, Hydrazide, or Azepane Moieties to the Triterpenoid Core Enhances an Activity Against M. tuberculosis

BACKGROUND

Triterpenoids exhibit a wide spectrum of antimicrobial activity.

OBJECTIVE

The objective of this study was to synthesize a series of nitrogen derivatives based on lupane, oleanane, and ursane triterpenoids with high antitubercular activity.

METHODS

Isonicotinoylhydrazones were prepared via the reaction of 3-oxotriterpenic acids or betulonic aldehyde with isoniazid (INH) in yields of 54-72%. N-Acylation of betulonic or azepanobetulinic acids led to lupane C28 hydrazides and dihydrazides. The derivatives were evaluated for their in vitro antimycobacterial activities against Mycobacterium tuberculosis (MTB) H37RV and single-drug resistance (SDR)-TB in the National Institute of Allergy and Infectious Diseases, USA. Molecular docking was performed to evaluate the possible binding modes of investigated compounds in the active site of Diterpene synthase (Rv3378c).

RESULTS

The obtained compounds are represented by C3 or C28 conjugates with hydrazine hydrate or INH. Some compounds demonstrated from high minimum inhibitory concentration (MIC ≤ 10 μg/mL) to excellent (MICs from 0.19 to 1.25 μg/mL) activity against MTB H37RV. Two lupane conjugates with INH were the leading compounds against MTB H37RV and some SDR-strains with MICs ranged from 0.19 to 1.70 μg/mL. Molecular docking of active compounds to diterpene synthase showed that these moieties accommodate the active site of the enzyme.

CONCLUSION

It was revealed that the conjugation of lupanes with INH at C3 is more effective than at C28 and the lupane skeleton is preferable among oleanane and ursane types. The replacement of native hexacarbocyclic A ring to seven-member azepane ring is favorably for inhibition of both MTB H37RV and SDR-strains. These data could possibly mean that the antitubercular activity against INH-resistant strains (INH-R) came from both triterpenoid and isoniazid parts of the hybrid molecules. Azepanobetulin showed the highest activity against both INH-R strains in comparison with other triterpenoids and INH. Thus, the introduction of hydrazone, hydrazide (dihydrazide), or azepane moieties into the triterpenoid core is a promising way for the development of new anti-tubercular agents.

Isolation and identification of belamcandaoids A-N from Belamcanda chinensis seeds and their inhibition on extracellular matrix in TGF-β1 induced kidney proximal tubular cells

Belamcandaoids A-N (1-14), fourteen new triterpenoids were isolated from the seeds of Belamcanda chinensis. Their structures including absolute configurations were assigned by using spectroscopic, computational, and crystallographic methods. All the compounds except 1 and 2 are 3,4-seco-triterpenoids belonging to fernane type. Biological evaluation results indicated that 3 and 13 could reduce fibronectin and collagen I expression respectively in TGF-β1 induced kidney proximal tubular cells.

Extensive expansion of the chemical diversity of fusidane-type antibiotics using a stochastic combinational strategy

Fusidane-type antibiotics, represented by helvolic acid, fusidic acid and cephalosporin P₁, are fungi-derived antimicrobials with little cross-resistance to commonly used antibiotics. Generation of new fusidane-type derivatives is therefore of great value, but this is hindered by available approaches. Here, we developed a stochastic combinational strategy by random assembly of all the post-tailoring genes derived from helvolic acid, fusidic acid, and cephalosporin P₁ biosynthetic pathways in a strain that produces their common intermediate. Among a total of 27 gene combinations, 24 combinations produce expected products and afford 58 fusidane-type analogues, of which 54 are new compounds. Moreover, random gene combination can induce unexpected activity of some post-tailoring enzymes, leading to a further increase in chemical diversity. These newly generated derivatives provide new insights into the structure‒activity relationship of fusidane-type antibiotics. The stochastic combinational strategy established in this study proves to be a powerful approach for expanding structural diversity of natural products.