Identification and characterization of organic and glycosidic acids in crude resin glycoside fraction from Calystegia hederacea

Eleven new glycosidic acid methyl esters from the crude resin glycoside fraction of Ipomoea alba seeds

Resin glycosides are characteristic of plants of the Convolvulaceae family and are well-known purgative ingredients in crude drugs, such as Rhizoma Jalapae, Orizaba Jalapa Tuber, and Pharbitidis Semen, which are used in traditional medicine and derived from plants belonging to this family. Isolated resin glycosides have demonstrated diverse biological activities, including antibacterial, ionophoric, anti-inflammatory, antiviral, and multidrug-resistance-modulating properties, as well as cytotoxicity against cancer cells. These compounds consist of hydroxyl fatty acid oligoglycosides (glycosidic acids), with portions of the saccharide moieties acylated with some organic acids to form the core structure. This study investigated the glycosidic acid components of a crude resin glycoside fraction obtained from a methanolic extract of Ipomoea alba L. seeds (Convolvulaceae). Eleven new glycosidic acid methyl esters and one known methyl ester were isolated from a glycosidic acid fraction treated with trimethylsilyldiazomethane in hexane. Their structures were determined using acidic hydrolysis and electrospray ionization-time of fight mass spectrometry and NMR spectral analyses. These compounds are penta-, tetra-, or triglycosides, with methyl 11S-hydroxytetradecanoate or methyl 11S-hydroxyhexadecanoate as the aglycone. Although D-quinovose and L-rhamnose are common monosaccharide components, the remaining monosaccharides are D-glucose, D-xylose, or D-fucose. The crude resin glycoside fraction showed non-negligible cytotoxicity against HL-60 human promyelocytic leukemia cells.

Identification and characterization of organic and glycosidic acids in the crude resin glycoside fraction of Ipomoea alba seeds

Resin glycosides act as laxatives in crude drugs derived from plants of the Convolvulaceae family. These compounds have exhibited antibacterial, ionophoric, anti-inflammatory, antiviral, and multidrug resistance-modulating properties, as well as cytotoxicity against cancer cells. This study investigated the organic acid, hydroxyl fatty acid, monosaccharide, and glycosidic acid components of the crude resin glycoside fraction obtained from the methanol extract of Ipomoea alba L. (Convolvulaceae) seeds, which was subjected to alkaline and acidic hydrolysis. The alkaline hydrolysis yielded acetic, isobutyric, (E)-2-methylbut-2-enoic, and 2S-methyl-3S-hydroxybutyric acids as organic acid components, along with a glycosidic acid fraction. The acidic hydrolysis of the glycosidic acid fraction resulted in the isolation of 11S-hydroxytetradecanoic and 11S-hydroxyhexadecanoic acids as hydroxyl fatty acid components, as well as d-glucose, d-quinovose, d-fucose, d-xylose, and l-rhamnose as monosaccharide components. In addition, 10 new glycosidic acid methyl esters were isolated from the glycosidic acid fraction treated with trimethylsilyldiazomethane-hexane, along with one known glycosidic acid methyl ester. Of these, eight compounds contained new glycans. Four of these compounds were unusual natural glycosides with four glycosidic linkages to one monosaccharide. Their structures were determined using MS and NMR spectral analyses, which provided valuable insights into the unique glycosidic composition of I. alba seeds.

Four new resin glycosides from Ipomoea muricata seeds: muricatins XIV-XVII

Ipomoea muricata (L.) Jacq. seeds (Convolvulaceae) are used as a traditional laxative and carminative medicine. Muricatins XIV (1), XV (2), XVI (3), and XVII (4), were isolated from I. muricata seeds as four new resin glycosides, along with seven known compounds, three of which were isolated for the first time as natural products; their structures were determined using MS and NMR spectroscopy. Compounds 1-4 are macrolactones (jalapins); the sugar moieties of 1, 2, and 4 are partially acylated with 2S-methylbutyric acid, while that of 3 is esterified with 2S-methylbutyric and 2S-methyl-3S-hydroxybutyric acids. In addition, the antiviral activities of the seven compounds obtained in this study, together with five known compounds obtained in our previous study into resin glycosides from I. muricata seeds, were evaluated against herpes simplex virus type 1 (HSV-1); their cytotoxicities against HL-60 human promyelocytic leukemia cells were also investigated. All examined jalapins exhibited similar or slightly weaker anti-HSV-1 activities than acyclovir, the positive control; however, the glycosidic acid of 4 was inactive, while its methyl ester was weakly active. On the other hand, cytotoxicity testing against HL-60 cells showed similar results to those observed during anti-HSV-1 activity testing, with the exception that one jalapin was less active.

The complete chloroplast genome sequence of Calystegia hederacea Wall. in Roxb. 1824 (Convolvulaceae) in Enshi, Hubei

Calystegia hederacea Wall. in Roxb. 1824 is a perennial herbaceous vine in the family Convolvulaceae and has several biological effects. Herein, we reported the first complete chloroplast genome of C. hederacea. The chloroplast genome sequence was 152,057 bp in length, comparing a large single-copy (LSC) region of 87,891 bp, a small single-copy (SSC) region of 19,866 bp, and a pair of inverted repeat (IR) regions of 22,150 bp. This sequenced chloroplast genome contained 126 predicted genes, including 81 protein-coding genes, 37 tRNA genes, and eight rRNA genes, and the total GC content of the chloroplast genome was 37.79%. Phylogenetic analysis revealed that C. hederacea was closely related to C. soldanella. The chloroplast genome presented in this study will enrich the genome information of the genus Calystegia and provide deeper insights into the evolution study of the family Convolvulaceae.

Identification and characterization of organic and glycosidic acids in the crude resin glycoside fraction of Ipomoea lacunosa seeds

Resin glycosides are commonly found in plants belonging to the Convolvulaceae family. Ipomoea lacunosa L. (Convolvulaceae) is an herbaceous vine native to the United States. The resin glycosides of this plant have not been studied in detail. In this study, the components of the crude resin glycoside fraction extracted from the seeds of I. lacunosa are characterized. Alkaline hydrolysis of the crude resin glycoside fraction obtained from methanolic extract of the seeds yielded three organic acids, namely, 2S-methylbutyric, (E)-2-methylbut-2-enoic, and 2R-methyl-3R-hydroxybutyric acids, and a glycosidic acid fraction. Acidic hydrolysis of the glycosidic acid fraction yielded hydroxyl fatty acid components, including 7S-hydroxydecanoic, 11S-hydroxytetradecanoic, 11S-hydroxyhexadecanoic, 3S,11S-dihydroxytetradecanoic, 3S,11S-dihydroxyhexadecanoic, and 3S,12S-dihydroxyhexadecanoic acids, as well as monosaccharide components, including d-glucose, d-quinovose, d-fucose, and l-rhamnose. Trimethylsilyldiazomethane-hexane treatment of the glycosidic acid fraction further yielded eleven previously undescribed glycosidic acid methyl esters and two known glycosidic acid methyl esters. The structures of the obtained compounds were characterized using various spectral techniques. Four of the undescribed compounds were hexaglycosides, five were heptaglycosides, and two were octaglycosides. The aglycone of these compounds was either methyl 11S-hydroxytetradecanoate, methyl 3S,11S-dihydroxytetradecanoate, or methyl 3S,11S-dihydroxyhexadecanoate. Among the undescribed compounds identified, eight contained novel glycans, and three were rare bisdesmosides with sugar linkages at the C-3 and C-11 positions of methyl 3S,11S-dihydroxytetradecanoate.

Two new resin glycosides, muricatins XII and XIII, from the seeds of Ipomoea muricata

Two new resin glycosides, muricatins XII (1) and XIII (2), were isolated from the crude resin glycoside fraction of the seeds of Ipomoea muricata (L.) Jacq. (Convolvulaceae), along with three known ones, muricatins V (3), VI (4), and IX (5). Compounds 1 and 2 contained new glycosidic acids, muricatic acids E (1a) and F (2a), respectively. The structures of these compounds were determined using data obtained from spectroscopy measurements and chemical evidence. The results suggested that 1 and 2 have macrolactone structures (jalapins). Furthermore, the cytotoxic activity of the crude resin glycoside fraction and 3-5 against HL-60 human promyelocytic leukaemia cells was evaluated. All tested samples demonstrated cytotoxic activities.

Isolation and structural characterization of eight new resin glycosides, calyhedins XVI-XXIII, from the rhizomes of Calystegia hederacea

Biological effects attributed to resin glycosides, including cytotoxicity against cancer cells and antibacterial, multidrug resistance-modulating, and antiviral activities have been documented. Penta-glycosides composed of calysolic acid A or calyhedic acid A, which are glycosidic acid components of the crude resin glycoside fraction of Calystegia hederacea, have not yet been isolated from this plant. In this study, eight new resin glycosides, termed calyhedins XVI (1)-XXIII (8), were isolated from the rhizomes of C. hederacea. Compounds 1-8 are penta- or hexa-glycosides with macrolactone structures, and their sugar moieties are partially acylated by five organic acids, including 2S-methylbutyric, (E)-2-methylbut-2-enoic, and 2R-methyl-3R-hydroxybutyric acids. Compounds 1-5 are the first identified macrocyclic resin glycosides with five monosaccharides obtained from this plant, and 2 and 4 are the first to be characterized as containing calyhedic acid A as the glycosidic acid component. Compounds 1-8 were of the four following macrolactone types: one with a 22-membered ring (5), another with a 23-membered ring (6-8), the third with a 27-membered ring (1, 3), and the fourth with a 28-membered ring (2, 4). Compounds 2-8 exhibited cytotoxic activity against HL-60 human promyelocytic leukemia cells comparable to that of the positive control, cisplatin.

The chemical composition of the essential oils of two Mediterranean species of Convolvulaceae: Convolvulus althaeoides subsp. tenuissimus collected in Sicily (Italy) and Calystegia silvatica collected in Algeria

Convolvulus L. and Calystegia R.Br. are two closely related genera of the Convolvulaceae family distributed in Asia, Mediterranean, Macaronesia, East Africa, and Arabia, including about 210 and 30 accepted species, respectively, of flowering plants, present as trees, shrubs, and herbs. The ethnomedical use of Convolvulus species dates to 1730s as they displayed profuse medicinal properties. In the present study, the not previously investigated chemical compositions of the essential oils from aerial parts of Convolvulus althaeoides subsp. tenuissimus (Sm.) Bat., collected in Sicily, and Calystegia sylvatica (Kit.) Griseb., collected in Algeria, were evaluated by GC-MS. The main components of the essential oil of the first one were β-caryophyllene (28.68%), γ-muurolene (23.75%), and γ-elemene (17.55%), whereas the C. silvatica essential oil was shown to be rich of valeranone (10.77%), viridiflorol (9.45%), and germacrene D (8.61%). Furthermore, a complete literature review on the ethno-pharmacological uses of Convolvulus and Calystegia species was performed.

Five new resin glycosides, calyhedins XI-XV, from Calystegia hederacea

Calystegia hederacea Wall. (Convolvulaceae) is a perennial herbaceous vine that grows widely in India and East Asia. All parts of this plant are used to treat various disorders such as menoxenia and gonorrhea. Four new resin glycosides, calyhedins XI (1)-XIV (4), were isolated from the rhizomes of C. hederacea. A new glycoside, calyhedin XV (5), was isolated from its leaves and stems. Alkaline hydrolysis of 1 and 2 furnished a new glycosidic acid, calyhedic acid G (1a), from 1 and a new acid, calyhedic acid H (2a), from 2 along with 2S-methylbutyric acid and 2R-methyl-3R-hydroxybutyric (2R,3R-nilic) acid. The structures of 1-5, 1a, and 2a were determined using MS and NMR spectral analyses. Compounds 1a and 2a had the same sugar moiety, β-D-glucopyranosyl-(1 → 6)-O-β-D-glucopyranosyl-(1 → 6)-O-β-D-glucopyranosyl-(1 → 3)-[O-β-D-glucopyranosyl-(1 → 3)-O-α-L-rhamnopyranosyl-(1 → 2)]-O-β-D-glucopyranosyl-(1 → 2)-β-D-fucopyranose, while their aglycones were 11S-dihydroxyhexadecanoic acid and 12S-dihydroxyhexadecanoic acid, respectively. These compounds are the first glycosidic acids, with fucose as the monosaccharide component obtained from the resin glycosides of C. hederacea. Compounds 1-5, comprising either 1a or 2a, were heptaglycosides with macrolactone structures, and their sugar moieties were partially acylated with 5 mol of organic acids comprising 2S-methylbutyric, (E)-2-methylbut-2-enoic, and 2R,3R-nilic acids. Compounds 1 and 5 had 22-membered rings, while 2-4 had 28-membered rings. In addition, 1 and 5 exhibited cytotoxic activity against HL-60 human promyelocytic leukemia cells, comparable to that of the positive control cisplatin.

Hederifolic acids A-D, hepta and hexasaccharides from the resin glycosides of Ipomoea hederifolia

Scarlet morning glory, Ipomoea hederifolia L. (Convolvulaceae), is an ornamental vine native to the Americas with oxytocic, cytotoxic, antipsychotic, anti-inflammatory, antioxidant, and antimicrobial properties. A chemical study of the glycosidic acids from the resin glycosides contained in the aerial parts was carried out, through their isolation as peracetylated derivatives, by recycling preparative liquid chromatography. Structure elucidation was performed by HR-MS in accordance with NMR. Four peracetylated derivatives of glycosidic acids, named hederifolic acids A-D, were identified as heptaglycosides and hexaglycosides linked to 3S,12S-dihydroxyheptadecanoic acid or 12 S-hydroxyheptadecanoic acid. Consequently, hederifolic acids B and D were found to be dehydroxylated homologs at C-3 of the fatty acid aglycones of hederifolic acids A and C, respectively.

Four new resin glycosides, calyhedins VII-X, from the rhizomes of Calystegia hederacea

Four new resin glycosides with macrolactone structures (jalapins), namely, calyhedins VII (1)-X (4), were isolated from the rhizomes of Calystegia hederacea Wall. (Convolvulaceae). The structures of 1-4 were determined based on spectroscopic data. They were classified into three ring types: a 27-membered ring (1), a 22-membered ring (2, 3), and a 23-membered ring (4). Their sugar moieties were partially acylated using five organic acids, including (E)-2-methylbut-2-enoic acid, 2S-methylbutyric acid, and 2 R-methyl-3R-hydroxybutyric acid. Compound 4 was the first genuine resin glycoside with calyhedic acid F as the glycosidic acid component. Additionally, the cytotoxic activities of 1, 2, and 4 towards HL-60 human promyelocytic leukaemia cells were evaluated. All compounds demonstrated almost the same activity as the positive control, cisplatin.

Identification and characterization of organic and glycosidic acids in the crude resin glycoside fraction from the leaves and stems of Calystegia japonica

The alkaline hydrolysis of the crude resin glycoside fraction from the leaves and stems of the plant Calystegia japonica Choisy (Convolvulaceae) yielded organic acid and glycosidic acid fractions. The organic acid fraction was esterified with p-bromophenacyl bromide to obtain p-bromophenacyl 2R-methyl-3R-hydroxybutyrate (1) and p-bromophenacyl (E)-2-methylbut-2-enoate (2). By treating the glycosidic acid fraction with trimethylsilyldiazomethane-hexane, seven new methyl esters of glycosidic acids, namely calyjaponic acid A methyl ester (3) calyjaponic acid B methyl ester (5), calyjaponic acid C methyl ester (6), calyjaponic acid D methyl ester (7), calyjaponic acid E methyl ester (8), calyjaponic acid F methyl ester (9), and calyjaponic acid G methyl ester (10), were isolated along with one known ester (4). Their structures were characterized based on spectroscopic and chemical analyses. Compounds 3-8 had the same sugar moiety, α-L-rhamnopyranosyl-(1 → 2)-O-β-D-glucopyranosyl-(1 → 2)-[O-α-L-rhamnopyranosyl-(1 → 6)]-O-β-D-glucopyranose, and the aglycones of 3-8 were methyl 3S,11S-dihydroxyhexadecanoate, methyl 3S,12S-dihydroxyhexadecanoate, methyl 11S-hydroxyhexadecanoate, methyl 11S-hydroxypentadecanoate, methyl 3S,11S-dihydroxypentadecanoate, and methyl 3S,12S-dihydroxypentadecanoate, respectively. Compounds 9 and 10 were derivatives of 3 and 4, respectively, in which the C-6 of the second glucosyl residue was methylated. Compounds 6-8 contained methyl esters of unusual odd-carbon fatty acids as aglycones. The cytotoxicity of the crude resin glycoside fraction and 3 against HL-60 human promyelocytic leukemia cells was evaluated further; both were either weakly active or inactive compared to the positive control, cisplatin.

Resin Glycosides from Convolvulaceae Family: An Update

Resin glycoside is a type of secondary metabolite isolated commonly from the Convolvulaceae family. It consists of oligosaccharides conjugated to organic acids with a larger percentage having a macrocyclic structure. The resin glycosides reported in this review is classified mostly based on the number of sugar units constructing the structure, which is correlated to the biological properties of the compounds. According to preliminary reviews, the protocols to isolate the compounds are not straightforward and require a special technique. Additionally, the structural determination of the isolated compounds needs to minimize the structure for the elucidation to become easier. Even though resin glycosides have a complicated structural skeleton, several total syntheses of the compounds have been reported in articles published from 2010 to date. This review is an update on the prior studies of the resin glycosides reported in 2010 and 2017. The review includes the classification, isolation techniques, structural determination, biological properties, and total synthesis of the resin glycosides.

Chemistry and biological activity of resin glycosides from Convolvulaceae species

Carbohydrate-based drug discovery has gained more and more attention during the last few decades. Resin glycoside is a kind of novel and complex glycolipids mainly distributed in plants of the family Convolvulaceae. Over the last decade, a number of natural resin glycosides and derivatives have been isolated and identified, and exhibited a broad spectrum of biological activities, such as cytotoxic, multidrug-resistant reversal on both microbial pathogens and mammalian cancer cells, antivirus, anticonvulsant, antidepressant, sedative, vasorelaxant, laxative, and α-glucosidase inhibitory effects, indicating their potential as lead compounds for drug discovery. A systematic review of the literature studies was carried out to summarize the chemistry and biological activity of resin glycosides from Convolvulaceae species, based on various data sources such as PubMed, Web of Science, Scopus, and Google scholar. The keyword "Convolvulaceae" was paired with "resin glycoside," "glycosidic acid," "glycolipid," or "oligosaccharide," and the references published between 2009 and June 2021 were covered. In this article, we comprehensively reviewed the structures of 288 natural resin glycoside and derivatives newly reported in the last decade. Moreover, we summarized the biological activities and mechanisms of action of the resin glycosides with pharmaceutical potential. Taken together, great progress has been made on the chemistry and biological activity of resin glycosides from Convolvulaceae species, however, more exploratory research is still needed, especially on the mechanism of action of the biological activities.

Calysepins I-VII, Hexasaccharide Resin Glycosides from Calystegia sepium and Their Cytotoxic Evaluation

Seven new hexasaccharide resin glycosides, named calysepins I-VII (1-7), with 27-membered rings, were obtained from the aerial parts of Calystegia sepium. Their structures with absolute configuration were established on the basis of spectroscopic data interpretation analysis and the use of chemical methods. They were defined as hexasaccharides composed of one d-quinovose, four d-glucose, and one l-rhamnose unit, and their sugar moieties were partially acylated by (2S)-methylbutanoic acid in 1-7 and (2R,3R)-nilic acid in 1-5 and 7, which mainly differed at the positions of acylation. Additionally, calysepin IV (4) exhibited cytotoxicity against A549 cells with an IC₅₀ value of 5.2 μM.

Calyhedins I-VI: Resin glycosides from the rhizomes of Calystegia hederacea

Six previously undescribed resin glycosides, calyhedins I-VI, were isolated from the rhizomes of Calystegia hederacea Wall., which are the first genuine resin glycosides isolated from C. hederacea. The structures of calyhedins I-VI were determined based on spectroscopic data and chemical evidence. All the compounds have macrolactone structures (jalapins), and their sugar moieties were partially acylated by five organic acids. Calyhedins I, II-V, and VI have 27-, 28-, and 23-membered rings, respectively, and calyhedins IV-VI are the first jalapins with a sugar chain consisting of seven monosaccharides. Additionally, the cytotoxic activity of calyhedins II and III toward HL-60 human promyelocytic leukemia cells was evaluated. Both compounds demonstrated almost the same activity as the positive control, cisplatin.

A New Glycosidic Acid, Muricatic Acid D, and Resin Glycosides, Muricatins X and XI, from the Crude Resin Glycoside Fraction of the Seeds of Ipomoea muricata

Alkaline hydrolysis of crude resin glycoside fraction of the seeds of Ipomoea muricata (L.) Jacq. (Convolvulaceae) yielded a new glycosidic acid, muricatic acid D; three known glycosidic acids, namely, muricatic acids A, B, and C; and three known organic acids, namely, isobutyric, 2S-methylbutyric, and 2S-methyl-3S-hydroxybutyric acid. Two new genuine resin glycosides with macrolactone structures (jalapins), muricatins X and XI, were also isolated from the fraction. Their structures were determined using spectroscopic data and chemical evidence.