Studies on the constituents of Asclepiadeceae plants. XVI. On the components of Metaplexis japonica Makino. 3. The structure of benzoylramanone

Caralluma edulis (Apocynaceae): A comprehensive review on its Traditional uses, Phytochemical profile and pharmacological effects

Caralluma edulis is a well-known species of the genus Caralluma from Apocynaceae, commonly known as chunga. Caralluma species are mostly succulent perennial herbs, several of which are edible species. The plant has an outstanding therapeutic background in the traditional system of treatment. It has been recommended for the treatment of a number medical disorder such as hypertension, Alzheimer disease, rheumatism, gastric problems and leprosy. Traditionally the stem was boiled in water and this extract was then used to cure diabetes. The pharmacological effects of C.edulis have also been explored in various in vitro and in vivo experiments. In this regard, the extract of the plant exhibited strong antioxidant activity, analgesic, against inflammation as well as xylene mediated ear edema for topical effects. The significant anti-hyperlipidemic effect of the plant extract is also reported. However, the extract was found insignificant in the reversal of alloxan-induced diabetes in rabbit model at test doses. These pharmacological effects are strongly supported by the presence of different bioactive phytochemicals in the plant. These groups of compounds include sterols, terpenoids, flavonoids, and pregnane glycosides. C.edulis is a very potential member of the genus Caralluma with strong traditional history, phytochemistry and phytopharmacology, needed further exploration for clinically used lead compounds. In this review, we have focused to combined different reported data on the traditional uses of the plant, phytochemical profile and pharmacological effects in different experimental assay and subsequent future prospects.

Three new C21 steroidal glycosides isolated from Metaplexis japonica and their potential inhibitory effects on tyrosine protein kinases

Three new steroidal glycosides, metapregnoside A-C (II-IV), together with one known compound, byzantionoside B (I), were isolated from the fresh whole herb of Metaplexis japonica by using high-speed countercurrent chromatography and semi-preparative liquid chromatography. Their structures and relative configurations were elucidated by spectroscopic methods including 1D NMR, 2D NMR and HR-ESI-MS. The potential targets of compound I-IV were identified by virtual screening. And the potential inhibitory effects of these compounds on tyrosine protein kinases were compared by molecular docking. Byzantionoside B (I) was the first isolated compound from Metaplexis genus. The docking score of metapregnoside C (IV) was the highest. And the sugar chain residues at position C-20 in the pregn-4-en-3-one derivatives is the main factor affecting their docking scores on tyrosine protein kinases Fes/Fps.

Metajapogenins A-C, Pregnane Steroids from Shells of Metaplexis japonica

Phytochemical investigation of the shells of Metaplexis japonica (Thunb.) Makino, belonging to the family of Apocynaceae, afforded three new pregnane steroids, metajapogenins A–C, along with three known compounds. The structures of the new compounds were elucidated as 12β,14β,17β-trihydroxypregna-3,5-dien-7,20-dione, 12β,14β,17β,20β-tetrahydroxypregna-3,5-dien-7-one; 3β,12β,14β,17β-tetrahydroxypregn-5-ene-7,20-dione on the basis of extensive spectroscopic evidence derived from 1D; 2D-NMR experiments and mass spectrometry. The known compounds included pergularin; 12-O-acetylpergularin; and pergularin-3-O-β-d-oleandropyranose; which were identified for the first time in the shells of M. japonica.

A review on ethnobotany, phytochemistry and pharmacology of plant genus C aralluma R. Br

Objectives

C aralluma is a xerophytic genus used as traditional medicine for the treatment of diabetes, inflammation, leprosy, obesity and rheumatism. Objectives of this review are to establish a relationship between traditional uses and scientific studies by critically evaluating the available fragmented literature on ethnobotany, pharmacology, phytochemistry and toxicology of genus Caralluma.

Key findings

Ethnomedical uses of Caralluma have been recorded from various countries such as China, India, Iran and Pakistan for six major classes of diseases including diabetes and gastrointestinal disorders. This review indicated the efficacy of genus Caralluma in several in vitro and in vivo pharmacological properties such as antimicrobial, antioxidant and anticancer activity. These bioactivity might be due to the presence of certain classes of compounds in genus Caralluma including pregnane glycosides, flavonoid glycosides and flavones.

Summary

Traditional uses and scientific evaluation of Caralluma indicates that it is one of the most widely used genus in some parts of the world. Further studies on the structural activity relationship of some of the isolated compound may improve their biological potency as well as scientific exploitation of traditional uses of the genus.

Acid epimerization of 20-keto pregnane glycosides is determined by 2D-NMR spectroscopy

Carbohydrates influence many essential biological events such as apoptosis, differentiation, tumor metastasis, cancer, neurobiology, immunology, development, host-pathogen interactions, diabetes, signal transduction, protein folding, and many other contexts. We now report on the structure determination of pregnane glycosides isolated from the aerial parts of Ceropegia fusca Bolle (Asclepiadaceae). The observation of cicatrizant, vulnerary and cytostatic activities in some humans and animals of Ceropegia fusca Bolle, a species endemic to the Canary Islands, encouraged us to begin a pharmacological study to determine their exact therapeutic properties. High resolution (1)H-NMR spectra of pregnane glycosides very often display well-resolved signals that can be used as starting points in several selective NMR experiments to study scalar (J coupling), and dipolar (NOE) interactions. ROESY is especially suited for molecules such that ωτ(c) ~ 1, where τ(c) are the motional correlation times and ω is the angular frequency. In these cases the NOE is nearly zero, while the rotating-frame Overhauser effect spectroscopy (ROESY) is always positive and increases monotonically for increasing values of τ(c). The ROESY shows dipolar interactions cross peaks even in medium-sized molecules which are helpful in unambiguous assignment of all the interglycosidic linkages. Selective excitation was carried out using a double pulsed-field gradient spin-echo sequence (DPFGSE) in which 180° Gaussian pulses are sandwiched between sine shaped z-gradients. Scalar interactions were studied by homonuclear DPFGSE-COSY and DPFGSE-TOCSY experiments, while DPFGSE-ROESY was used to monitor the spatial environment of the selectively excited proton. Dipolar interactions between nuclei close in space can be detected by the 1D GROESY experiment, which is a one-dimensional counterpart of the 2D ROESY method. The C-12 and C-17 configurations were determined by ROESY experiments.

Pregnane steroidal glycosides and their cytostatic activities

Four new steroidal glycosides such as 3-O-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1 → 4)-β-D-oleandropyranosyl-(1 → 4)-β-D-cymaropyranosyl-(1 → 4)-β-D-cymaropyranoside-12-β-tigloyl-14-β-hydroxy-17-β-pregnane (1), 3-O-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1 → 4)-β-D-oleandropyranosyl-(1 → 4)-β-D-cymaropyranosyl-(1 → 4)-β-D-cymaropyranoside-12-β-(2'-amino)-benzoyl-14-β-hydroxy-17-β-pregnane (2), 3-O-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1 → 4)-β-D-oleandropyranosyl-(1 → 4)-β-D-cymaropyranosyl-(1 → 4)-β-D-cymaropyranoside-12-β-14-β-dihydroxy-17-α-pregnane (3) and 3-O-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1 → 4)-β-D-oleandropyranosyl-(1 → 4)-β-D-cymaropyranosyl-(1 → 4)-β-D-cymaropyranoside-12-β-14-β-dihydroxy-17-β-pregnane (4) were isolated from the aerial parts of Ceropegia fusca Bolle (Asclepiadaceae), a crassulacean acid metabolism plant, an endemic species to the Canary Islands that has been used in traditional medicine as a cicatrizant, vulnerary and disinfectant. The dichloromethane extract exhibited significant cytostatic activity against HL-60, A-431 and SK-MEL-1 cells, human leukemic, epidermoid carcinoma and melanoma cells, respectively. As shown in Table I, compounds 1 and 2 showed very similar IC(50) values. The acetylation of 1 to give the diacetate 5 increases 5-fold the cytotoxicity against HL-60 cells. Compounds 3 and 4 did not show cytotoxicity at the assayed concentrations. With respect to the compounds containing only the steroid ring (6-8), the presence of a charged O-amino-benzoyl but not a tigloyl group improved the cytotoxicity.

An appetite suppressant from Hoodia species

Studies conducted at the Council for Scientific and Industrial Research (CSIR, South Africa) identified extracts from Hoodia species, in particular Hoodia pilifera and Hoodia gordonii, as possessing appetite suppressing properties. Two pregnane glycosides were isolated by fractionation of the dried stems of H. gordonii. Their structures were determined as 3beta-[beta-D-thevetopyranosyl-(1-->4)-beta-D- cymaropyranosyl-(1-->4)-beta-D-cymaropyranosyloxy]-12beta-tigloyloxy-14beta-hydroxypregn-5-en-20-one (1) and 3beta-[beta-D-cymaropyranosyl-(1-->4)-beta-D-6-thevetopyranosyl-(1-->4)-beta-D-cymaropyranosyl-(1-->4)-beta-D-cymaropyranosyloxy]-12beta-tigloyloxy-14beta-hydroxypregn-5-en-20-one (2) on the basis of spectroscopic studies and conversion to known compounds. Compounds 1 and 2 were also isolated from H. pilifera. Compound 1 was tested for its appetite suppressant properties in rats by oral gavage at 6.25-50 mg/kg and the results showed that all doses resulted in a decrease of food consumption over an eight day period and a body mass decrease when compared to the control sample receiving only the vehicle. In a comparative study against a fenfluramine control sample, compound 1 resulted in a reduction in food intake over the study period, with a concomitant overall decrease in body weight while fenfluramine resulted in a small decrease in food intake, but an increase in body weight (though less than control group) over the same period of time.

New oxypregnane glycosides from appetite suppressant herbal supplement Hoodia gordonii

Hoodigosides A-K (1-11), eleven new oxypregnane glycosides and a previously reported oxypregnane glycoside P57AS3 were isolated from the aerial parts of Hoodia gordonii. The structures of these 12-O-beta-tigloyl isoramanone glycosides were determined on the basis of chemical evidence and extensive spectroscopic methods that include one-dimensional and two-dimensional NMR. Cytotoxicity and antioxidant activities of these compounds were tested in cell based assays where they were found to be inactive.