A new sesquiterpene lactone from Elephantopus tomentosus

The specialized sesquiterpenoids produced by the genus Elephantopus L.: Chemistry, biological activities and structure-activity relationship exploration

The genus Elephantopus L. is a valuable resource rich in sesquiterpenoids with structural diversity and various bioactivities, showing great potential for applications in medicinal field and biological industry. Up to now, over 129 sesquiterpenoids have been isolated and identified from this plant genus, including 114 germacrane-type, 7 guaianolide-type, 5 eudesmane-type, 1 elemanolide-type, and 2 bis-sesquiterpenoids. These sesquiterpenoids were reported to show a diverse range of pharmacological properties, including cytotoxic, anti-tumor, anti-inflammatory, antimicrobial, and antiprotozoal. Consequently, some of them were identified as active scaffolds in the design and development of drugs. Considering that there is currently no overview available that covers the sesquiterpenoids and their biological activities in the Elephantopus genus, this article aims to comprehensively review the chemical structures, biosynthetic pathways, pharmacological properties, and structure-activity relationship of sesquiterpenoids found in the Elephantopus genus, which will establish a theoretical framework that can guide further research and exploration of sesquiterpenoids from Elephantopus plants as promising therapeutic agents.

HSQC-based small molecule accurate recognition technology discovery of diverse cytotoxic sesquiterpenoids from Elephantopus tomentosus L. and structural revision of molephantins A and B

Elephantopus tomentosus L. is a perennial herb taxonomically belonging to the family Asteraceae, which has been used as a folk medicine for the treatment of hepatobiliary diseases. Sesquiterpenoids from this plant have broad biological activities, including anti-tumor, anti-inflammatory, and antibacterial effects. In this study, fifteen structurally diverse sesquiterpenoids comprised 11 germacrane-type and 4 eudesmane-type sesquiterpenoids were prioritized to isolated from Elephantopus tomentosus L. based on the HSQC-based Small Molecule Accurate Recognition Technology (SMART) strategy. Among them, ten sesquiterpenoids were previously unreported, and their structures were elucidated by spectroscopic data, computational methods, single-crystal X-ray diffraction crystallographic data or electronic circular dichroism calculations. In addition, the structures of two known sesquiterpenoids, molephantin A and B, which were reported to possess E-geometry for the Δ¹⁽¹⁰⁾ double bond, were revised by reanalyzing their spectroscopic and X-ray crystallographic data. Some sesquiterpenoids exhibited significant cytotoxic activities against Hep3B and HepG2 cell lines.

Highly Oxidized Germacranolides from Elephantopus tomentosus and the Configurational Revision of Some Previously Reported Analogues

Highly oxidized germacranolides are mainly found in the genus Elephantopus, contain a characteristic ten-membered molecular core that is highly flexible, and exhibit potential cytotoxic properties. However, their configurations were assigned ambiguously in previous reports due to spectroscopic observation of macrocyclic systems. Herein, 17 highly oxidized germacranolides, including 12 new germacranolides (1-12), were isolated from Elephantopus tomentosus. Their structures were characterized by spectroscopic data analysis combined with X-ray crystallography and ECD calculations, and it was possible to propose configurational revisions of five previously reported analogues (13-17). Cytotoxic activities for 1-17 against two hepatocellular carcinoma cell lines (HepG2 and Hep3B) were tested, and compounds 1-10 and 13-16 generated IC₅₀ values of 2.2-9.8 μM. Furthermore, the observed cytotoxic activity of 1 was determined as being mediated by inducing the apoptosis of HepG2 and Hep3B cells via mitochondrial dysfunction.

Antibacterial and Antifungal Sesquiterpenoids: Chemistry, Resource, and Activity

Infectious diseases caused by bacteria and fungi are threatening human health all over the world. It is an increasingly serious problem that the efficacies of some antibacterial and antifungal agents have been weakened by the drug resistance of some bacteria and fungi, which makes a great need for new antibiotics. Sesquiterpenoids, with abundant structural skeleton types and a wide range of bioactivities, are considered as good candidates to be antibacterial and antifungal agents. In the past decades, many sesquiterpenoids were isolated from plants and fungi that exhibited good antibacterial and antifungal activities. In this review, the names, source, structures, antibacterial and antifungal degrees, and mechanisms of sesquiterpenoids with antibacterial and antifungal activity from 2012 to 2022 are summarized, and the structure-activity relationship of these sesquiterpenoids against bacteria and fungi is also discussed.

Dietary Supplementation With Didancao (Elephantopus scaber L.) Improves Meat Quality and Intestinal Development in Jiaji Ducks

Didancao (Elephantopus scaber L.) has been used as a traditional herbal medicine and has exhibited a beneficial role in animal health. This study aimed to investigate the effects of dietary supplementation with E. scaber on growth performance, meat quality, intestinal morphology, and microbiota composition in ducks. A total of 480 Jiaji ducks (42 days old, male:female ratio = 1:1) were randomly assigned to one of four treatments. There were six replicates per treatment, with 20 ducks per replicate. The ducks in the control group (Con) were fed a basal diet; the three experimental groups were fed a basal diet supplementation with 30 (T1), 80 (T2), and 130 mg/kg (T3) of E. scaber. After a 48-day period of supplementation, growth performance, meat quality, intestinal morphology, and microbiota composition were evaluated. The results showed that no differences were observed in the final body weight, average daily feed intake, and average daily gain among the four groups. Compared with that in the Con group, the feed conversion in the T1 and T2 groups was increased significantly; the T2 group was shown to decrease the concentration of alanine aminotransferase in serum; the T3 group was lower than the Con group in the concentration of aspartate aminotransferase and was higher than the Con group in the concentration of high-density lipoprotein-cholesterol. The highest concentration of creatinine was observed in the T1 group. The T2 group was higher than the Con group in the contents of Phe, Ala, Gly, Glu, Arg, Lys, Tyr, Leu, Ser, Thr, Asp, and total amino acids in the breast muscle. Moreover, the T2 group was higher than the Con group in the contents of meat C18:2n−6 and polyunsaturated fatty acid. The concentration of inosinic acid in the T1, T2, and T3 groups was significantly higher than that in the Con group. However, the Con group was higher than the T2 or T3 group in the Zn content. The T2 group was lower than the Con group in the jejunal crypt depth. The T3 group was higher than the Con group in the ileal villus height and the ratio of villus height to crypt depth. In addition, the T3 group had a trend to significantly increase the abundance of Fusobacteria. Compared with the Con group, the T1 and T2 groups displayed a higher abundance of Subdoligranulum. Collectively, dietary supplementation with 80 mg/kg of E. scaber improves meat quality and intestinal development in ducks.

Three new sesquiterpene lactones from the whole plants of Elephantopus scaber

Three new sesquiterpene lactones, named scabertopinolides H - J (1 - 3), along with four known ones, desacylisodeoxyelephantopin 2-methylbutyrate (4), iso-17,19-dihydrodeoxyelephantopin (5), scabertopinolide D (6) and (2R,6R,7R,8S)-8-tigloyloxy-1(10),4(5),11(13)-germacratrien-2,15,6,12-diolide (7) were isolated from the whole plants of Elephantopus scaber. Their structures were elucidated by extensive analysis of spectroscopic data (including IR, UV, HRESIMS, 1 D and 2 D NMR) and single-crystal X-ray. These isolated compounds showed effective anti-inflammatory effects on LPS-stimulated RAW 264.7 cells with IC₅₀ values of 6.27 ± 0.18 to 18.31 ± 1.38 μM.

Cytotoxic and anti-inflammatory active phloroglucinol derivatives from Rhodomyrtus tomentosa

Seven undescribed phloroglucinol derivatives, tomentodiones N-T, and eleven known ones were isolated from Rhodomyrtus tomentosa. Tomentodione N is the first example of a β-triketone unit coupled with an isoamyl alcohol through a furan fused-ring, and tomentodiones N, S, T were three racemates. The undescribed structures were elucidated by means of spectroscopic, X-ray diffraction, electronic circular dichroism calculation, and chemical methods. In addition, the isolated compounds were determined for the cytotoxic activities on HeLa cells and anti-inflammatory activities in LPS-stimulated RAW 264.7 cells.

Sesquiterpene lactones from Elephantopus mollis and their anti-inflammatory activities

Seven sesquiterpene lactones, 8-O-methacryloylelephanpane, 2,4-bis-O-methyl-8-O-methacryloylelephanpane, 4-O-ethyl-8-O-methacryloylelephanpane, 8-O-methacryloylisoelephanpane, 2-O-demethyltomenphantopin C, molephantin A, molephantin B, along with ten known ones, were isolated from Elephantopus mollis (Asteraceae). Their structures were elucidated by extensive analysis of spectroscopic data (IR, UV, HRESIMS, 1D and 2D NMR). The isolates were evaluated for their anti-inflammatory activities on LPS-stimulated RAW 264.7 cells, and all tested compounds exhibited potent anti-inflammatory effects with IC₅₀ values of 0.57 ± 0.17 to 14.34 ± 1.61 μM, except that compound tomenphantopin C exhibited moderate anti-inflammatory activity with IC₅₀ values of 59.97 ± 1.53 μM.

Natural sesquiterpenoids

This review covers the isolation, structural determination, synthesis and chemical and microbiological transformations of natural sesquiterpenoids. The literature from January to December 2012 is reviewed, and 471 references are cited.