Glycosides from Chinese medicinal plant, Hemsleya panacis-scandens, and structure-taste relationship to cucurbitane glycosides

A comprehensive review of Siraitia grosvenorii (Swingle) C. Jeffrey: chemical composition, pharmacology, toxicology, status of resources development, and applications

Siraitia grosvenorii (Swingle) C. Jeffrey (S. grosvenorii), a perennial indigenous liana from the Cucurbitaceae family, has historically played a significant role in southern China's traditional remedies for various ailments. Its dual classification by the Chinese Ministry of Health for both medicinal and food utility underscores its has the potential of versatile applications. Recent research has shed light on the chemical composition, pharmacological effects, and toxicity of S. grosvenorii. Its active ingredients include triterpenoids, flavonoids, amino acids, volatile oils, polysaccharides, minerals, vitamins, and other microconstituents. Apart from being a natural sweetener, S. grosvenorii has been found to have numerous pharmacological effects, including alleviating cough and phlegm, preventing dental caries, exerting anti-inflammatory and anti-allergic effects, anti-aging and anti-oxidative, hypoglycemic, lipid-lowering, anti-depression, anti-fatigue, anti-schizophrenic, anti-Parkinson, anti-fibrotic, and anti-tumor activities. Despite its versatile potential, there is still a lack of systematic research on S. grosvenorii to date. This paper aims to address this gap by providing an overview of the main active components, pharmacological efficacy, toxicity, current status of development and application, development dilemmas, and strategies for intensive exploitation and utilization of S. grosvenorii. This paper aims to serve as a guide for researchers and practitioners committed to exploiting the biological resources of S. grosvenorii and further exploring its interdisciplinary potential.

Structurally diverse cucurbitane-type triterpenoids from the tubers of Hemsleya chinensis with cytotoxic activity

Ten previously undescribed cucurbitane-type triterpenoids, namely hemslyencins A-F (1-6) and hemslyencosides A-D (7-10), together with twenty previously reported compounds (11-30), were isolated from the tubers of Hemsleya chinensis. Their structures were elucidated by unambiguous spectroscopic data (UV, IR, HR-ESI-MS, 1D and 2D NMR data). Hemslyencins A and B (1 and 2) possessing unique 9, 11-seco-ring system with a six-membered lactone moiety, were the first examples among of the cucurbitane-type triterpenoids, and hemslyencins C and D (3 and 4) and hemslyencoside D (10) are the infrequent pentacyclic cucurbitane triterpenes featuring a 6/6/6/5/6 fused system. The cytotoxic activities of all isolated compounds were evaluated against MCF-7, HCT-116, HeLa, and HepG2 cancer cells, and their structure-activity relationships (SARs) was discussed as well. Compounds 17, 25, and 26 showed significant cytotoxic effects with IC50 values ranging from 1.31 to 9.89 μM, among which compound 25 induced both apoptosis and cell cycle arrest at G2/M phase in a dose dependent manner against MCF-7 cells.

Cucurbitane triterpenes from Hemsleya chinensis tubers and their anti-inflammatory activities

Six new cucurbitane-type triterpenes, hemchinins A-F (1-6), together with thirteen known ones (7-19) were isolated from ethyl acetate extraction of Hemsleya chinensis tubers. Compounds 1-2 were a group of cucurbitane triterpenes possessing an infrequent pentacyclic framework. Their structures were established by comprehensive UV, IR, HRMS, 1D/2D NMR, and ECD analyses. Bioassay results showed that most isolated compounds exhibited anti-inflammatory actions, in which compounds 13 and 15 exhibited stronger activities at 6.25 μM, with NO inhibition rates of 49.00 ± 0.05% and 48.40 ± 0.10%, respectively.

A Review of the Phytochemistry and Pharmacology of the Fruit of Siraitia grosvenorii (Swingle): A Traditional Chinese Medicinal Food

Siraitia grosvenorii (Swingle) C. Jeffrey ex Lu et Z. Y. Zhang is a unique economic and medicinal plant of Cucurbitaceae in Southern China. For hundreds of years, Chinese people have used the fruit of S. grosvenorii as an excellent natural sweetener and traditional medicine for lung congestion, sore throat, and constipation. It is one of the first species in China to be classified as a medicinal food homology, which has received considerable attention as a natural product with high development potential. Various natural products, such as triterpenoids, flavonoids, amino acids, and lignans, have been released from this plant by previous phytochemical studies. Phar- macological research of the fruits of S. grosvenorii has attracted extensive attention, and an increasing number of extracts and compounds have been demonstrated to have antitussive, expectorant, antiasthmatic, antioxidant, hypoglycemic, immunologic, hepatoprotective, antibacte- rial, and other activities. In this review, based on a large number of previous studies, we summarized the related research progress of the chemical components and pharmacological effects of S. grosvenorii, which provides theoretical support for further investigation of its biological functions and potential clinical applications.

Cucurbitane triterpenoid entities derived from Hemsleya penxianensis triggered glioma cell apoptosis via ER stress and MAPK signalling cross-talk

In the present study, six new cucurbitane type compounds, including three triterpenoids hemsleyacins P-R (6-7, 13) and three cucurbitane-type triterpenoid glycosides hemsleyaosides L-N (15-17), along with seventeen known cucurbitacin analogues were separated from the root tuber of Hemsleya penxianensis and elucidated based on NMR and HRESIMS. Then, 23 analogues of three types, namely, polyhydroxy-type (I) (1-7), monohydroxy-type (II) (8-13), and glycosides-type (III) (14-23), were assessed for their antitumor activity and structure-activity relationship analysis (SAR). We determined temozolomide (TMZ)-resistant GBM cell was the most sensitive to the tested compounds, and found hemsleyaoside N (HDN) displayed the best antineoplastic potency. Furthermore, we confirmed the anti-glioma activity of HDN in patient-derived recurrent GBM strains, GBM organoid (GBO) and orthotopic nude mouse models. Investigations exploring the mechanism made clear that HDN induced synchronous activation of UPR and MAPK signaling, which triggered deadly ER stress and apoptosis. Taken together, the potent antitumor activity of HDN warrants further comprehensive evaluation as a novel anti-glioma agent.

Structure-Dependent Activity of Plant-Derived Sweeteners

Human sensation for sweet tastes and the thus resulting over-consumption of sugar in recent decades has led to an increasing number of people suffering from caries, diabetes, and obesity. Therefore, a demand for sugar substitutes has arisen, which increasingly has turned towards natural sweeteners over the last 20 years. In the same period, thanks to advances in bioinformatics and structural biology, understanding of the sweet taste receptor and its different binding sites has made significant progress, thus explaining the various chemical structures found for sweet tasting molecules. The present review summarizes the data on natural sweeteners and their most important (semi-synthetic) derivatives until the end of 2019 and discusses their structure–activity relationships, with an emphasis on small-molecule high-intensity sweeteners.

Bioactive triterpenoid saponins from the tubers of Hemsleya amabilis Diels

Five new cucurbitane-type triterpenoid saponins Xuedanosides A-E (1-5) were isolated from the medicinal plant Hemsleya amabilis Diels by silica gel column, octadecylsilyl (ODS) column, and pre-HPLC techniques. Their structures were determined by spectroscopic analysis and examined alongside existing data from prior studies. Separated compounds were evaluated for their cytotoxic activity in HeLa, HCT-8, MCF-7 and HepG2 human cancer cell lines, and compounds 1 and 2 showed significant effects against HeLa cells with IC₅₀ values of 3.21 and 8.57 μM, respectively.

Cucurbitane-type triterpenes from the tubers of Hemsleya penxianensis and their bioactive activity

The tubers of the medicinal plant Hemsleya penxianensis (Cucurbitaceae) yielded 11 cucurbitane-type triterpenes Xuedanencins A-K by silica gel column, ODS column, and pre-HPLC techniques. Their structures were determined by spectroscopic analysis and examined alongside existing data from prior studies. Separated compounds were evaluated for cytotoxic activity against the Hela human cancer cell line and compounds 7 and 8 showed significant cytotoxicity with IC₅₀ values at 1.82 and 2.45 μM, respectively.

Cucurbitane Glucosides from the Crude Extract of Siraitia grosvenorii with Moderate Effects on PGC-1α Promoter Activity

Seven new cucurbitane glucosides, 11-oxomogrosides III E and IV (1 and 2), 11-oxoisomogroside V (3), 7-oxomogrosides III E and IV (4 and 5), and mogrosides VI A and VI B (6 and 7), were separated from the crude extract of Siraitia grosvenorii. The new structures were defined by analysis of their ¹H and ¹³C NMR, 2D NMR, and HRESIMS data. Especially, the band-selective constant time HSQC and band-selective constant time HMBC techniques were recuited to elucidate the structures of the complex glucoside moieties. Using the PGC-1α promoter driven luciferase reporter assay, the isolated compounds were examined for PGC-1α promoter activity.

Chemistry and pharmacology of Siraitia grosvenorii: a review

Siraitia grosvenorii is a perennial herb endemic to Guangxi province of China. Its fruit, commonly known as Luo hanguo, and has been used for hundreds of years as a natural sweetener and as a traditional medicine for the treatment of pharyngitis, pharyngeal pain, as well as an anti-tussive remedy in China. Based on ninety-three literary sources, this review summarized the advances in chemistry, biological effects, and toxicity research of S. grosvenorii during the past 30 years. Several different classes of compounds have been isolated or detected from various parts of S. grosvenorii, mainly triterpenoids, flavonoids, polysaccharides, amino acids, and essential oils. Various types of extracts or individual compounds derived from this species exhibited a wide array of biological effects e.g. anti-tussive, phlegm-relieving, anti-oxidant, immunomodulatory, liver-protecting, glucose-lowering, and anti-microbial. The existing research has shown that extracts and individual compounds from S. grosvenorii are basically non-toxic. Finally, some suggestions for further research on specific chemical and pharmacological properties of S. grosvenorii are proposed in this review.

Three new cucurbitane triterpenoids from Hemsleya penxianensis and their cytotoxic activities

Two new cucurbitane glycosides, hemslepenside A (1) and 16,25-O-diacetyl-cucurbitacin F-2-O-β-d-glucopyranoside (3), one new cucurbitacin, 16-O-acetyl-cucurbitacin F (2), along with three known cucurbitane compounds, were isolated from the roots of Hemsleya penxianensis. The structures of 1-6 were established on the basis of extensive spectroscopic and chemical methods. The isolated compounds were evaluated for their cytotoxic activities against different three human cancer cell lines, with IC50 values in the low microgram range.

Cucurbitane triterpenoids from Hemsleya penxianensis

Two new cucurbitacins, jinfushanencins A (1) and B (2), seven new cucurbitane glycosides, jinfushanosides E-K (3–9), along with nine known analogues, were obtained from the tubers of Hemsleya penxianensis. Their structures were elucidated on the basis of extensive spectroscopic and chemical methods. Selected isolates were tested their anti-HIV-1 activities, and compound 5 showed weak anti-HIV-1 in C8166 cell (EC₅₀ = 5.9 µg/mL) with a selectivity index of 13.5.

Suppressive effect of Siraitia grosvenorii extract on dicyclanil-promoted hepatocellular proliferative lesions in male mice

Dicyclanil (DC) generates reactive oxygen species (ROS) due to Cyp1a1 induction, and DNA damage caused by oxidative stress is probably involved in hepatocarcinogenesis in mice. To clarify the modifying effect of the Siraitia grosvenorii extract (SGE), which has antioxidative properties, we employed a 2-stage liver carcinogenesis model in partially hepatectomized male ICR mice. Mice maintained on diet containing DC at a concentration of 1,500 ppm for 9 weeks after a single intraperitoneal injection of diethylnitrosamine (DEN) at a dose of 30 mg/kg and they were given water containing 2,500 ppm of SGE for 11 weeks including 2 weeks as pre-administration on DC. SGE inhibited the induction of gamma-glutamyltranspeptidase-positive hepatocytes, lipid peroxidation, and gene expression of Cyp1a1, all of which were caused by DC. To examine whether SGE indirectly inhibits Cyp1a1 expression induced by inhibition of aryl hydrocarbon receptor (Ahr)-mediated signal transduction caused by DC, mice with high (C57BL/6J mice) and low affinities (DBA/2J mice) to Ahr were given DC-containing diet and/or SGE-containing tap water for 2 weeks. Cyp1a1 gene expression was significantly lower in C57BL/6J mice administered DC + SGE than in C57BL/6J mice administered DC alone; there was no difference in the Cyp1a1 expression between DBA/2J mice administered DC + SGE and DC alone. These results suggest that SGE suppresses the induction of Cyp1a1, leading to inhibition of ROS generation and consequently inhibited hepatocarcinogenesis, probably due to suppression of Ahr activity.

[Studies on the constituents of cucurbitaceous plants]

I have an opportunity to have co-operative studies with Chinese group of Kunming Institute of Botany. Since then, I have investigated the chemical constituents of a number of Chinese plants of Araliaceae, Umbelliferae, Labiatae, Cucurbitaceae and other families. This review describes the structural elucidation of the cucurbitane, oleanane and dammarane glycosides, and their biological activities under the joint studies on cucurbitaceous plants, Bolbostemma, Hemsleya, Siraitia and Neoalsomitra species. New oleanane glycosides having novel cyclic structure were isolated from Bolbostemma paniculatum. The potent solubilizing effect of these compounds was investigated. A number of cucurbitane glycosides were isolated from Hemsleya carnosiflora, H. panacis-scandens, Siraitia grosvenorii and S. siamensis. Some of these glycosides taste sweet, bitter or tasteless. The structure-taste relationships of the glycosides of a 3-alpha-hydroxy-cucurbit-5-ene-type triterpene have been discussed. Anti-tumor-promotion effects as well as the ecdysteroid agonist and antagonist activities of these cucurbitane glycosides were investigated. New dammarane glycosides were isolated from Neoalsomitra integrifoliola.

Octanorcucurbitane and cucurbitane triterpenoids from the tubers of Hemsleya endecaphylla with HIV-1 inhibitory activity

Two new cucurbitacins, endecaphyllacins A (1) and B (2), together with six known analogues (3-8), were isolated from the tubers of Hemsleya endecaphylla. The structures of 1 and 2 were elucidated by NMR and MS spectroscopic analysis. The relative stereochemistry of 1 was determined by single-crystal X-ray diffraction. Compound 4 (cucurbitacin B) showed potent anti-HIV-1 in C8166 cells (EC=0.09 microg/mL) with a selectivity index of 16.7.

The bioactivity-guided isolation and structural identification of toxic cucurbitacin steroidal glucosides from stemodia kingii

A histologically validated murine model for the ovine intoxication by Stemodia kingii was used as a bioassay to guide the isolation of several groups of toxins from Stemodia kingiL Two of the toxins from one group were purified sufficiently to allow structural analysis and a determination of their median lethal doses (LD50) for oral administration to mice. A combination of acid hydrolysis, elemental analysis, HPLC-MS, 1D-NMR (1H, 13C) and 2D-NMR (1H-1H COSY, 13C-1H HSQC and HMBC, and gNOESY) was used to define stemodiosides B3 and B4 as cucurbitacin steroidal glucosides. Thus stemodioside B3 is (24Z)-3 alpha-(beta-glucopyranosyloxy)-2 beta,20,27-trihydroxy- 19-(10 -9 beta)-abeo-10alpha-lanost-5,24-diene- 11-one and stemodioside B4 is (23E)-3 alpha-(beta-glucopyranosyloxy)-20,20,22,27-tetrahydroxy- 19-( 10-9 beta)-abeo- 10 alpha-lanost-5,23-diene- 11-one. The approximate oral LD50s for stemodiosides B3 and B4 in mice were estimated to be 99 and 42 mg/kg body weight, respectively.

Cucurbitacins and cucurbitane glycosides: structures and biological activities

The natural cucurbitacins constitute a group of triterpenoid substances which are well-known for their bitterness and toxicity. Structurally, they are characterized by the tetracyclic cucurbitane nucleus skeleton, namely, 19-(10-->9beta)-abeo-10alpha-lanost-5-ene (also known as 9beta-methyl-19-norlanosta-5-ene), with a variety of oxygen substitutions at different positions. According to the characteristics of their structures, cucurbitacins are divided into twelve categories. The biological effects of the cucurbitacins are also covered.

Anticarcinogenic activity of natural sweeteners, cucurbitane glycosides, from Momordica grosvenori

To search for cancer chemopreventive agents from natural resources, many phytochemicals and food additives have been screened. Consequently, two natural sweeteners, mogroside V and 11-oxo-mogroside V isolated from the fruits of Momordica grosvenori, exhibited strong inhibitory effect on the primary screening test indicated by the induction of Epstein-Barr virus early antigen (EBV-EA) by a tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). These sweet glycosides, having cucurbitane triterpenoid aglycon, exhibited the significant inhibitory effects on the two-stage carcinogenesis test of mouse skin tumors induced by peroxynitrite (ONOO-) as an initiator and TPA as a promoter. Further, 11-oxo-mogroside V also exhibited the remarkable inhibitory effect on two-stage carcinogenesis test of mouse skin tumor induced by 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter.

Highly sweet compounds of plant origin

The demand for new alternative "low calorie" sweeteners for dietetic and diabetic purposes has increased worldwide. Although the currently developed and commercially used highly sweet sucrose substitutes are mostly synthetic compounds, the search for such compounds from natural sources is continuing. As of mid-2002, over 100 plant-derived sweet compounds of 20 major structural types had been reported, and were isolated from more than 25 different families of green plants. Several of these highly sweet natural products are marketed as sweeteners or flavoring agents in some countries as pure compounds, compound mixtures, or refined extracts. These highly sweet natural substances are reviewed herein.

The applications and future implications of bitterness reduction and inhibition in food products

Numerous food and beverage products, bulking agents, and pharmaceuticals have pleasant as well as unpleasant bitter-tasting components in their taste profile. In numerous cases, the bitter taste modality is an undesirable trait of the product. Bitter characteristics found in some food systems have been removed or diminished by various known processes, but no universally applicable bitter inhibitor has ever been recognized. Some indications point to a receptor-mediated phenomenon for sweetness and bitterness. Research on sweet compounds has led to knowledge of sweetness inhibitors and could ultimately lead to bitterness inhibitors. To facilitate efforts to rationally design a universal bitter inhibitor or cocktail of such, a review of the bitter taste phenomena and known methods of bitterness reduction and inhibition have been compiled.