Two new 5(14)-membered type cyclopeptide alkaloids from root bark of Ziziphus spina-christi (L.) Desf

Six 5(14)-membered ring type of cyclopeptide alkaloids (CPAs), including two undescribed members, 1-hydro,2β-methoxy-mauritine-A (1) and 1-hydro,2α-methoxy-mauritine-A (2), together with four known compounds, mauritine-A (3), mauritine C (4), amphibine-A (5), and amphibine-E (6), were isolated from the root bark of Ziziphus spina-christi (L.) Desf., Their structures were determined by multiple spectral analyses, including UV, IR, 1D NMR, 2D NMR, EI-MS, HR-EI-MS, FAB-MS and ESI-MS, and by comparison with literature. All six CPAs were tested in vitro for cytotoxicity by three human cancer cell lines (MCF7, H460 and Hela) and a human normal cell line (BJ). None of the compounds showed cytotoxicity towards all tested cell lines.

Genus Ziziphus: A comprehensive review on ethnopharmacological, phytochemical and pharmacological properties

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Ziziphus (Rhamnaceae) contains 58 accepted species that are extensively used by local people and medicinal practitioners in arid and semi-arid regions for the treatment of diarrhoea, dysentery, cholera, diabetic, hypertension, inflammation, intestinal spasm, liver, malaria and other diseases. Aims of this review: This review article documents and critically assesses, for the first time; up to date categorized information about botanical traits, distribution, traditional uses, phytochemistry, pharmacological and toxicological effects of Ziziphus species.

METHODS

Information was collected systematically from electronic scientific databases including Google Scholar, Science Direct, PubMed, Web of Science, ACS Publications, Elsevier, SciFinder, Wiley Online Library and CNKI, as well as other literature sources (e.g., books).

KEY FINDINGS

The phytochemical investigations of plants of this genus have led to the identification of about 431 chemical constituents. Cyclopeptide alkaloids and flavonoids are the predominant groups. The crude extracts and isolated compounds exhibit a wide range of in vitro and in vivo pharmacologic effects, including antimicrobial, antitumour, antidiabetic, antidiarrhoeal, anti-inflammatory, antipyretic, antioxidant and hepatoprotective activities. Toxicity studies indicate that Ziziphus species seems to be non-toxic at typical therapeutic doses.

CONCLUSION

Phytochemical and pharmacological studies have demonstrated that Ziziphus species are important medicinal herbs with prominent bioactivities. The focus so far has only been on ten species; however, plants of this genus can potentially yield a wide range of other products with different properties. Meticulous studies on pharmaceutical standardisation, mode of action of the active constituents and toxicity of Ziziphus species are needed to meet the growing demands of the pharmaceutical industry and to exploit their preventive and therapeutic potential fully.

Opuntisines, 14-membered cyclopeptide alkaloids from fruits of Opuntia stricta var. dillenii isolated by high-performance countercurrent chromatography

Extracts of Opuntia stricta var. dillenii fruits were fractionated by semi-preparative high-performance countercurrent chromatography (HPCCC) to study the secondary metabolite formation, whereby HPCCC showed a superior separation capacity to fractionate minor metabolites compared to HPLC. A family of new peptides was detected in semi-polar fractions when monitoring the HPCCC separation by off-line injections of fractions to ESI-MS/MS. Planar structures of the major compounds, two 14-ring-membered cyclopeptide alkaloids, which were named opuntisines A and B, were elucidated by 1D- and 2D-NMR spectroscopy and HR-ESI-MS/MS spectrometry, while a combination of chemical derivatisation and degradation revealed the stereo-configurations. Specifically, the methods of Marfey and Mosher indicated l-Glu, l-Ile, l-Phe and 1S-configurations, respectively; ROESY correlations revealed 8S, 9S. The novel opuntisine A showed moderate activity against the Gram-negative bacterium Escherichia coli, but no further antibacterial, antifungal nor cytotoxic effects. This bioactive natural product class is reported for the first time in the plant family Cactaceae.

New cyclopeptide alkaloids from the whole plant of Justicia procumbens L

Three novel 14-membered cyclopeptide alkaloids, justicianenes B-D (1-3), were isolated from the EtOH extract of the whole plant of Justicia procumbens L., and their structures were determined on the basis of detailed NMR spectroscopic data and the absolute stereochemistry of the ring-bonded α-amino acids in the cyclopeptide alkaloids were determined by ECD spectra. The isolated compounds were evaluated for their in vitro cytotoxicity against human cancer cell lines, including brest cancer MCF-7, cervix carcinoma HeLa, lung cancer A549 and H460, and diphyllin (14) showed moderate cytotoxicity against the HeLa, A549 and H460 cells with IC₅₀ of 9.13, 23.12, 42.34 µM, respectively, justicianene D showed weak cytotoxicity against the MCF-7 cell with inhibition rate of 50% at the concentration of 90 µM.

Isolation and structure elucidation of cyclopeptide alkaloids from the leaves of Heisteria parvifolia

Heisteria parvifolia Sm. is prescribed in traditional medecine against numerous diseases in Côte d'Ivoire. Due to the shortcoming in scientifical knowledge of use of this species, our investigations revealed five undescribed cyclopeptide alkaloids added to one known derivative namely anorldianine. These compounds were elucidated by 1D and 2D-NMR experiments and comparison with literature data, and confirmed by HR-ESI-MS. Cytotoxic activity evaluation of these compounds against the chronic myeloid leukemia (K565) cell line exhibited an antiproliferative activity with cell growth inhibition from 13% to 46%.

Antibacterial activity of Discaria americana Gillies ex Hook (Rhamnaceae)

ETHNOPHARMACOLOGY RELEVANCE

Discaria americana Gillies ex Hook (sin. Discaria febrifuga and Discaria longispina) (Rhamnaceae) is a plant native from Rio Grande do Sul (Southern Brazil), Uruguay and Argentine, and has been used in Brazilian traditional medicine as antipyretic agent, and for stomach disorders. In Rio Grande do Sul, Uruguay and Argentine, the roots, in decoction, are used as tonic and febrifuge. Although it is a plant widely used by the population, there are no studies proving this popular use.

MATERIAL AND METHODS

The crude neutral methanol extract, and pure isolated alkaloids, were investigated in vitro for antimicrobial activities against four Gram-positive bacteria: Staphylococcus aureus, Bacillus subtillis, Bacillus cereus, Enterococcus faecium; and five Gram-negative bacteria: Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Salmonella enterica serovar Typhimurium and Pseudomonas aeruginosa.

RESULTS

The crude neutral methanol (CME) extract of the root bark of Discaria americana showed antibacterial activity, ranging from 62.5 to 250 μg mL^-1 (MIC), against the tested bacteria. From the fractions obtained from the crude extract, the basic ethereal fraction (BEF) showed to be more effective, with MICs between 31.5 and 125 μg mL^-1 against the tested bacteria. The bioassay-guided fractionation of the ethyl ether basic fraction yielded eight cyclopeptide alkaloids: frangufoline (1), frangulanine (2), adouetine Y' (3), discarine A (4) discarine B (5), discarine C (6), discarene C (7) and discarine D (8). When evaluated against the Gram-positive bacteria Enterococcus faecium, discarine B (5) proved to be the most active alkaloid with a MIC/MLC = 0.77/1.55 μg mL^-1, near the most active antibacterial agent levofloxacin (MIC/MLC = 0.77/0.77 μg mL^-1). Moreover, discarine C (6) was the more active alkaloid against Salmonella enterica serovar Typhimurium, with a MIC/MLC = 3.1/6.2 μg mL^-1, the same observed for the antibacterial agent azithromycin. Kinetic measurements of the bacteriolytic activities of discarine B (5) against Enterococcus faecium (Gram-positive), and of discarine C (6) against Salmonella enterica serovar Typhimurium (Gram-negative) were determined by optical density based on real time assay, suggesting that both mode of action are partially bacteriolytic.

CONCLUSION

In conclusion, five 14-membered cyclopeptide alkaloids isolated from Discaria americana Gillies ex Hook (Rhamnaceae) showed promising antibacterial activity, making this metabolites a class of scientific interest. The good activity presented by the extract and the alkaloids against the Gram-positive bacteria Enterococcus faecium and against the Gram-negative bacteria Salmonella enterica serovar Typhimurium, Enterobacter. aerogenes and Escherichia coli, corroborate with the popular use of this plant for stomach disorders and as antifebrile.

Metabolites profiling of Ziziphus leaf taxa via UHPLC/PDA/ESI-MS in relation to their biological activities

Ziziphus plants are well recognized for their nutritive and medicinal value worldwide, albeit their chemical profile has yet to be fully reported. The secondary metabolites profile of three traditionally used Ziziphus leaf accessions was investigated via ultra-high performance liquid chromatography coupled to photodiode array and electrospray ionization mass detectors (UHPLC/PDA/ESI-MS). A total of 102 metabolites were characterized revealing the first holistic approach onto Ziziphus leaf metabolome and to include the first report of several novel flavonoids and cyclopeptide alkaloids. Fragmentation pattern for cyclopeptide alkaloids was proposed via ESI-MS. Principal component analysis (PCA) revealed close metabolite resemblance among Z. spina-christi and Z. mauritiana leaf specimens found enriched in saponins and distinct from that of Z. jujuba in which quercetin-3-O-(2-pentosyl)-rhamnoside was most abundant. Further, in-vitro antioxidant, anti-inflammatory and antidiabetic assays revealed for Z. spina-christi and Z. mauritiana strong effects compared to Z. jujuba and in correlation with their metabolites repertoire.

Isolation and structure elucidation of cyclopeptide alkaloids from Ziziphus nummularia and Ziziphus spina-christi by HPLC-DAD-MS and HPLC-PDA-(HRMS)-SPE-NMR

Seven cyclopeptide alkaloids were isolated from the stem bark of Ziziphus nummularia and Ziziphus spina-christi. Three previously undescribed compounds were identified: nummularine-U, spinanine-B and spinanine-C, together with the known compounds mauritine-F, nummularine-D, nummularine-E and amphibine-D. For their purification either semi-preparative HPLC with DAD and ESIMS detection or HPLC-PDA-(HRMS)-SPE-NMR was applied, together with conventional separation methods. Their structures were elucidated by spectroscopic means.

Jubanines F-J, cyclopeptide alkaloids from the roots of Ziziphus jujuba

Five Ib-type cyclopeptide alkaloids, jubanines F-J (1-5), and three known compounds, nummularine B (6), daechuine-S3 (7), and mucronine K (8) were isolated from the roots of Ziziphus jujuba. Their structures were fully characterized by spectroscopic analyses in combination with chemical derivatization. Compounds 1-3, and 6 were evaluated for their antiviral activity against the porcine epidemic diarrhea virus (PEDV). Compounds 2, 3, and 6 showed potent inhibitory effects on PEDV replication.

Analgesic and anti-inflammatory studies of cyclopeptide alkaloid fraction of leaves of Ziziyphus nummularia

Ziziyphus nummularia (family: Rhamnaceae) is a thorny small bush, grows in abundance in the grazing lands of the arid areas of Rajasthan, India. It is an important ethnomedicinal plant of the Thar Desert; local inhabitants use every part of the plant as medicine. Kernels are prescribed in pregnancy as soporific, antiemetic and for relieving abdominal pain. The insect gall is powered and given orally with water to cure bone fracture. Crushed root is applied on the paining shoulder of the bullock. The decoction of leaves is used for the treatment of cough and cold; leaves are also regarded as diaphoretic and prescribed in typhoid. Paste of leaves is used for healing of cuts, boils and cutaneous disease. It is widely used in pain and inflammatory conditions. Z. nummularia contains a unique group of alkaloids known as cyclopeptide alkaloids, in continuation of our work carried out on the leaves of Z. nummularia , present study was initiated to explore antiinflammatory and analgesic potential of cyclopeptide alkaloids isolated from the leaves of Z. nummularia (IFZN). Anti-inflammatory activity was tested against rat paw oedema, mouse peritonitis and cotton pellet granuloma. For screening of analgesic activity, acetic acid induced writhing, tail flick and hot plate test were performed. IFZN 30 mg/kg shows the anti-oedematogenic effect against paw oedema induced by carrageenan, dextran, serotonin and histamine; IFZN 20 and 30 mg/kg were found to have highly significant anti-nociceptive effects. Result of pharmacological studies indicated that IFZN is a potent and efficacious analgesic agent. The analgesic activity of IFZN is mediated by the peripheral as well as central pathways.