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

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.

Phytochemical Analysis and Profiling of Antitumor Compounds of Leaves and Stems of Calystegia silvatica (Kit.) Griseb

Anti-tumor compounds from natural products are being investigated as possible alternatives for cancer chemotherapeutics that have serious adverse effects and tumor resistance. Calystegia silvatica was collected from the north coast of Egypt and extracted via methanol and n-hexane sub-fraction. The biologically active compounds of Calystegia silvatica were identified from the methanol and n-hexane extracts from the leaves and stems of the plant using GC-MS and HPLC. The antitumor properties of both parts of the plant were investigated against cancer and non-cancer cell lines using the MTT assay, and the IC₅₀ in comparison to doxorubicin was calculated. The main compounds identified in the methanol extract were cis-vaccenic acid and trans-13-octadecenoic acid in the leaves and stems, respectively, and phenyl undecane and 3,7,11,15 tetramethyl-2-hexadeca-1-ol in the n-hexane extracts of the leaves and stems, respectively. Both parts of the plant contained fatty acids that have potential antitumor properties. The methanol extract from the stems of C. silvatica showed antitumor properties against HeLa, with an IC₅₀ of 114 ± 5 μg/mL, PC3 with an IC₅₀ of 137 ± 18 μg/mL and MCF7 with an IC₅₀ of 172 ± 15 μg/mL, which were greater than Caco2, which had an IC₅₀ of 353 ± 19 μg/mL, and HepG2, which had an IC₅₀ of 236 ± 17 μg/mL. However, the leaf extract showed weak antitumor properties against all of the studied cancer cell lines (HeLa with an IC₅₀ of 208 ± 13 μg/mL, PC3 with an IC₅₀ of 336 ± 57 μg/mL, MCF7 with an IC₅₀ of 324 ± 17 μg/mL, Caco2 with an IC₅₀ of 682 ± 55 μg/mL and HepG2 with an IC₅₀ of 593 ± 22 μg/mL). Neither part of the plant extract showed any cytotoxicity to the normal cells (WI38). Therefore, C. silvatica stems may potentially be used for the treatment of cervical, prostate and breast cancer.

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.