A New Xanthone Glycoside from Mangifera indica L.: Physicochemical Properties and In Vitro Anti-Skin Aging Activities

A new xanthone glycoside, 1,3,5,6-tetrahydroxyxanthone-C-4-β-d-glucopyranoside was isolated from the methanol extract of Mangifera indica leaves (Anacardiaceae) growing in Egypt. The structure was clarified by 1D and 2D-NMR spectroscopic data. The physicochemical properties of the compound such as lipophilicity, solubility, and formulation considerations were predicted via in silico ADMET technique using the SwissADME server. This technique provided Lipinski’s rule of five, such as GIT absorption, distribution, metabolism, and skin permeation. The in vitro inhibitory activities against aging-mediated enzymes such as collagenase, elastase, hyaluronidase, and tyrosinase were assessed. The compound exhibited remarkable anti-collagenase, anti-elastase, anti-hyaluronidase, and anti-tyrosinase effects with IC₅₀ values of 1.06, 419.10, 1.65, and 0.48 µg/mL, respectively, compared to the positive control. The compound showed promising predicted aqueous solubility and reasonable skin penetration suggesting the suitability of the compound for topical formulation as an anti-aging agent for cosmetic preparations.

Medicinal Importance, Pharmacological Activities and Analytical Aspects of a Flavonoid Glycoside 'Nicotiflorin' in the Medicine

BACKGROUND

Herbal products are derived from different natural sources, mainly used as a source of food material and medicine in the health sectors since ancient times. Herbal products have gained popularity in modern medicine due to their beneficial health properties and pharmacological activities. Flavonoids are an important class of secondary metabolites found to be present in medicinal plants and their derived products. Flavonoids have been known for their anti-allergic, anti-bacterial, anti-diabetic, anti-inflammatory, anti-viral, anti-proliferative, anti-mutagenic, antithrombotic, anti-carcinogenic, anti-oxidant and hepatoprotective activities in the medicine. Nicotiflorin is a flavonoidal class phytochemical, found in medicinal plants, including Traditional Chinese medicine.

METHODS

Scientific data on the medicinal importance and pharmacological activities of nicotiflorin have been collected and analyzed in the present work in order to know the therapeutic importance of nicotiflorin in medicine. Scientific data have been collected from Google, Google Scholar, Science Direct, PubMed and Scopus and analyzed in the present work. Analytical techniques data of separation, isolation and identification of nicotiflorin have also been collected and presented in the current work. Further biological importance of flavonoidal class phytochemicals was also discussed in the present work to understand the biological importance of nicotiflorin in medicine as it belongs to the flavonoid class.

RESULTS

Scientific data analysis revealed the therapeutic importance and pharmacological activities of nicotiflorin. Nicotiflorin has significant biological potential against coronavirus, ischemia, renal impairment, hepatic complication, memory dysfunction and myocardial infarction. The biological potential of nicotiflorin against α-glucosidase and α-amylase enzymes, multiple myeloma cells and insulin secretion has also been discussed in the present work. Analytical data revealed the significance of modern analytical tools in medicine for the isolation, separation and quantification of nicotiflorin.

CONCLUSION

Scientific data analysis of different research works revealed the biological importance and therapeutic potential of nicotiflorin in medicine.

Cytotoxic cardenolides from Calotropis gigantea

Sixteen cardiac glycosides, including five previously undescribed compounds, were extracted and purified from whole plants of Calotropis gigantea (L.). Spectroscopic data and electronic circular dichroism (ECD) analyses were used to determine their structures. Calogiganin C is the first naturally occurring example of a cardenolide containing a 7-membered lactone in ring A. The cytotoxic activities of these compounds against A172, U251, AGS, PANC-1, HepG2, HCT116 and NCI-H226 cell lines were evaluated. Four of them exhibited the most potent growth inhibitory activity against a panel of human cancer cell lines, including A172, U251, AGS, PANC-1 and HCT116. Notably, uscharidin and calotropin showed pronounced cytotoxicities at low nanomolar concentrations against A172 and U251 cells, and possible cell death mechanism studies manifested that these two compounds induced G2/M cell cycle arrest, which demonstrated promising anticancer potential.

Interaction of (+)-Strebloside and Its Derivatives with Na+/K+-ATPase and Other Targets

Docking profiles for (+)-strebloside, a cytotoxic cardiac glycoside identified from Streblus asper, and some of its derivatives and Na+/K+-ATPase have been investigated. In addition, binding between (+)-strebloside and its aglycone, strophanthidin, and several of their other molecular targets, including FIH-1, HDAC, KEAP1 and MDM2 (negative regulators of Nrf2 and p53, respectively), NF-κB, and PI3K and Akt1, have been inspected and compared with those for digoxin and its aglycone, digoxigenin. The results showed that (+)-strebloside, digoxin, and their aglycones bind to KEAP1 and MDM2, while (+)-strebloside, strophanthidin, and digoxigenin dock to the active pocket of PI3K, and (+)-strebloside and digoxin interact with FIH-1. Thus, these cardiac glycosides could directly target HIF-1, Nrf2, and p53 protein-protein interactions, Na+/K+-ATPase, and PI3K to mediate their antitumor activity. Overall, (+)-strebloside seems more promising than digoxin for the development of potential anticancer agents.

Synthesis of Cardiotonic Steroids Oleandrigenin and Rhodexin B

This article describes a concise synthesis of cardiotonic steroids oleandrigenin (7) and its subsequent elaboration into the natural product rhodexin B (2) from the readily available intermediate (8) that could be derived from the commercially available steroids testosterone or DHEA via three-step sequences. These studies feature an expedient installation of the β16-oxidation based on β14-hydroxyl-directed epoxidation and subsequent epoxide rearrangement. The following singlet oxygen oxidation of the C17 furan moiety provides access to oleandrigenin (7) in 12 steps (LLS) and a 3.1% overall yield from 8. The synthetic oleandrigenin (7) was successfully glycosylated with l-rhamnopyranoside-based donor 28 using a Pd(II)-catalyst, and the subsequent deprotection under acidic conditions provided cytotoxic natural product rhodexin B (2) in a 66% yield (two steps).

Anticancer potential of cardiac glycosides and steroid-azole hybrids

Steriods are well-known scaffolds that have a widespread occurrence in different compounds characterized by extensive biological properties including anticancer activity. Structural modifications on steroids always generate potential lead compounds with superior bioactivity, and creation of steroid hybrids by combining steroid with other anticancer pharmacophores in one molecule, which can exert the anticancer activity through different mechanisms, is one of the most promising strategies to enhance efficiency, overcome drug resistance and reduce side effects. Sugars and azoles, can act on diverse receptors, proteins and enzymes in cancer cells, are pharmacologically significant scaffolds in the development of novel anticancer agents. Therefore, steroid-sugar hybrids cardiac glycosides and steroid-azole hybrids are privileged scaffolds for the discovery of novel anticancer candidates. This review emphasized on the development, the structure-activity relationship and the mechanism of action of cardiac glycosides and steroid-azole hybrids with potential application for fighting against various cancers including drug-resistant forms to facilitate further rational design of novel drug candidates covering articles published between 2015 and 2020.

A new isoflavone glycoside from Abrus cantoniensis

A new isoflavone glycoside named as 8-O-methylrelusin-7-O-β-D-apifuranosyl-(1→2)-β-D-glucopyranoside (1), together with two known compounds, 8-O-methylrelusin-7-O-β-D-glucopyranoside (2) and isobiflorin (3), were isolated from Abrus cantoniensis. The structure of the new compound was elucidated on the basis of spectroscopic methods including extensive 1D NMR, 2D NMR, and HRESIMS. This is the first report of isoflavone from Abrus cantoniensis. Moreover, all isolated compounds were evaluated for their cytotoxicity against SMMC-7721 and MHCC97-H cell lines.[Formula: see text].

Discovery of a stable vitamin C glycoside in crab apples (Malus sylvestris)

Non-targeted LC-MS metabolomics on fruit of three wild and domesticated apple species (Malus sylvestris, M. sieversii and M. domestica) showed that two crab apple (M. sylvestris) accessions were distinguished by high concentrations of an ascorbic acid glycoside (AAG). This was partly purified, but key NMR signals were masked by inseparable sucrose. Reference samples of 2-O-β-D-glucopyranosyl L-ascorbic acid and 2-O-β-D-galactopyranosyl L-ascorbic acid were synthesised, but both coincided with the crab apple AAG on LC-MS. Peracetylation of the crab apple extract allowed both purification and characterisation, and the AAG was proven to be 2-O-β-D-glucopyranosyl L-ascorbic acid by comparison of ¹H NMR, HRMS and HPLC data with synthesised peracetylated ascorbyl glycoside standards. The stability of the natural AA 2-β-glycoside was similar to synthetic 2-O-α-D-glucopyranosyl L-ascorbic acid, used widely in cosmetic and pharmaceutical products. This discovery in crab apples (Rosaceae) is only the fourth reported occurrence of any ascorbyl glycoside from plants, the others being from Cucurbitaceae, Solanaceae and Brassicaceae. It is hypothesised that AAGs may be more widespread in plants than currently realised.

Unusual glycosidic labdane diterpenoids with cytotoxicity from the root of Phlomoides betonicoides

Chemical investigation on the root of Phlomoides betonicoides led to the isolation of six undescribed diterpenoid glycosides, phlomoidesides A-F, along with two known ones using various chromatographic techniques. The structures of these compounds were determined by extensive spectroscopic analyses (including 1D, 2D-NMR and HRMS), single crystal X-ray diffraction, and calculated ¹³C NMR. The glycoside modifications of phlomoidesides A-F are rare in natural products, and a plausible biosynthetic pathway for these unusual glycosides was proposed. Phlomoidesides A, D, F, and phlomisosides V, Ш were cytotoxic against three human tumor cell lines, NCI-H1975, HepG2 and MCF-7, with IC₅₀ values ranging from 7.5 to 75.7 μM. Phlomoideside B only showed weak cytotoxicity against NCI-H1975, with IC₅₀ of 53.0- μM.

Dramatic dietary shift maintains sequestered toxins in chemically defended snakes

Unlike other snakes, most species of Rhabdophis possess glands in their dorsal skin, sometimes limited to the neck, known as nucho-dorsal and nuchal glands, respectively. Those glands contain powerful cardiotonic steroids known as bufadienolides, which can be deployed as a defense against predators. Bufadienolides otherwise occur only in toads (Bufonidae) and some fireflies (Lampyrinae), which are known or believed to synthesize the toxins. The ancestral diet of Rhabdophis consists of anuran amphibians, and we have shown previously that the bufadienolide toxins of frog-eating species are sequestered from toads consumed as prey. However, one derived clade, the Rhabdophis nuchalis Group, has shifted its primary diet from frogs to earthworms. Here we confirm that the worm-eating snakes possess bufadienolides in their nucho-dorsal glands, although the worms themselves lack such toxins. In addition, we show that the bufadienolides of R. nuchalis Group species are obtained primarily from fireflies. Although few snakes feed on insects, we document through feeding experiments, chemosensory preference tests, and gut contents that lampyrine firefly larvae are regularly consumed by these snakes. Furthermore, members of the R. nuchalis Group contain compounds that resemble the distinctive bufadienolides of fireflies, but not those of toads, in stereochemistry, glycosylation, acetylation, and molecular weight. Thus, the evolutionary shift in primary prey among members of the R. nuchalis Group has been accompanied by a dramatic shift in the source of the species' sequestered defensive toxins.

Periplocin, the most anti-proliferative constituent of Periploca sepium, specifically kills liposarcoma cells by death receptor mediated apoptosis

BACKGROUND

During a screening of Chinese plants traditionally used for the treatment of cancer and related diseases, extracts of the root bark of Periploca sepium Bunge showed strong cytotoxic activity.

PURPOSE

Isolate and identify cytotoxic compounds from P. sepium and investigate the effects and mechanism of action on different cancer cell lines.

METHODS

Extracts obtained with solvents of different polarities of the root bark of P. sepium were tested for their anti-proliferative effects. The most active extract was subjected to activity-guided fractionation using different chromatographic methods. The most active compound was further investigated on sarcoma cell lines regarding its effects concerning apoptosis, DNA damage and death receptor expression.

RESULTS

We isolated the cardiac glycosides periplocin, glucosyl divostroside, periplogenin, periplocymarin and periplocoside M with periplocin exhibiting the lowest IC₅₀ value against leukemia and liposarcoma cells. Liposarcomas are rare tumors within the heterogeneous group of soft tissue sarcomas and respond poorly to conventional treatments. Periplocin led to growth inhibition and apoptosis induction by changing the expression of death receptors and inducing DNA double strand breaks in SW-872 cells.

CONCLUSION

Periplocin displays a promising mechanism of action in sarcoma cells because altering the death receptor expression is an interesting target in sarcoma treatment especially to overcome TRAIL resistance.

Redox-responsive PEGylated self-assembled prodrug-nanoparticles formed by single disulfide bond bridge periplocymarin-vitamin E conjugate for liver cancer chemotherapy

Periplocymarin (PPM), a cardiac glycoside, has a narrow therapeutic index, poor tumor selectivity and severe cardiovascular toxicity which hinder its wide clinical applications in cancer treatment. Herein, we report novel redox-responsive prodrug-nanoparticles (MPSSV-NPs) self-assembled by co-nanoprecipitation of PPM-vitamin E conjugate and a PEG derivative of linoleate (mPEG2000-LA) in water. It was found that the characteristics of PPM-vitamin E nanoparticles (PSSV-NPs) were improved through co-nanoprecipitation with increased percentages of mPEG2000-LA. Moreover, the MPSSV-NPs were optimized according to the in vitro release and cytotoxicity study. Furthermore, the optimized MPSSV-NPs dramatically enhanced the circulation time and tumor distribution of PSSV-NPs after single intravenous injection. The in vivo studies in malignant H22-bearing mice revealed that MPSSV-NPs could effectively suppress tumor growth without causing obvious systemic toxicity. Altogether, these results suggested that MPSSV-NPs could offer a safe, multifunctional and viable nanoplatform for cardiac glycosides in cancer treatment.

Forsythoneosides A-D, Neuroprotective Phenethanoid and Flavone Glycoside Heterodimers from the Fruits of Forsythia suspensa

Forsythoneosides A-D (1-4), four unusual adducts of a flavonoid unit fused to a phenylethanoid glycoside through a pyran ring or carbon-carbon bond, and four new phenylethanoid glycosides (5-8) were isolated from the fruits of Forsythia suspensa, together with nine known compounds. The structures of 1-8, including their absolute configurations, were elucidated by spectroscopic data as well as experimental and calculated electronic circular dichroism analysis. Compounds 2 and 4 inhibited PC12 cell damage induced by rotenone, and increased cell viability from 53.9 ± 7.1% to 70.1 ± 4.0% and 67.9 ± 5.2% at 0.1 μM, respectively.

Cardiotonic Substances from Bersama Abyssinica Fres. Sub. Species Abyssinica

Three crystalline materials have been isolated from the leaves of Bersama abyssinica sub. sp. abyssinica, N.O. Melianthaceae. Some chemical and pharmacological evidence is presented that these materials are bufodienolide aglycones. The material isolated in greatest quantity has a toxicity similar to that of scillaridin.