Bioactive lignans and flavones with in vitro antioxidant and neuroprotective properties from Rubus idaeus rhizome

Neuroprotective neolignan glycosides from the pseudobulbs of Bletilla striata

Four undescribed neolignan glycosides, bletineosides A-D (1-4) were isolated from the pseudobulbs of Bletilla striata. Their structures with absolute configurations were elucidated on the basis of spectroscopic analyses, along with acidic hydrolysis reactions and ECD experiments. All isolates were evaluated for their neuroprotective activities against glutamate-induced PC12 cell injury. Compound 3 and 4 showed significantly neuroprotective effects at the concentration of 10 μM when compared with the model group. Compounds 1-4 represented the first examples of neolignan glycosides from the genus Bletilla. This study disclosed the potency of Bletilla striata as a new source of anti-neurodegenerative agents.

Bioactive Compounds and Antioxidant Activity in the Fruit of Rosehip (Rosa canina L. and Rosa rubiginosa L.)

Rosehips (Rosa spp., Rosaceae) are wild rose bushes with more than 100 species. Its fruits vary in colour and size, depending on the species, and are recognised for their nutritional characteristics. Ten samples of Rosa canina L. and Rosa rubiginosa L. fruits were collected at different geographical points from Southern Chile. Nutrients such as crude protein and minerals and functional properties such as phenolic compounds, ascorbic acid, and also antioxidant activities were evaluated by HPLC-DAD-ESI-MS/MS. The results revealed a high content of bioactive compounds, primarily ascorbic acid (6.0 to 8.2 mg g^-1 fresh weight (FW)), flavonols (427.9 ± 0.4 μg g^-1 FW) and antioxidant activity. We established a relationship between the antioxidant activity using Trolox equivalent antioxidant capacity (TEAC), cupric reducing antioxidant capacity (CUPRAC) and 2,2-diphenyl radical (DPPH) methods and the concentration of uncoloured compounds, such as flavonols and catechin. This antioxidant activity was primarily associated with the samples from Gorbea, Lonquimay, Loncoche, and Villarrica localities, and all of them were of the species Rosa rubiginosa L. The results here obtained represent novel information of rosehip fruits. In this sense, the reported information about compounds and antioxidant activities in rosehip fruits allowed us to continue new lines of research in relation to the potential formulation of new functional foods and also in the treatment and/or prevention of some diseases.

Reaction with ROO• and HOO• Radicals of Honokiol-Related Neolignan Antioxidants

Honokiol is a natural bisphenol neolignan present in the bark of Magnolia officinalis, whose extracts have been employed in oriental medicine to treat several disorders, showing a variety of biological properties, including antitumor activity, potentially related to radical scavenging. Six bisphenol neolignans with structural motifs related to the natural bioactive honokiol were synthesized. Their chain-breaking antioxidant activity was evaluated in the presence of peroxyl (ROO•) and hydroperoxyl (HOO•) radicals by both experimental and computational methods. Depending on the number and position of the hydroxyl and alkyl groups present on the molecules, these derivatives are more or less effective than the reference natural compound. The rate constant of the reaction with ROO• radicals for compound 7 is two orders of magnitude greater than that of honokiol. Moreover, for compounds displaying quinonic oxidized forms, we demonstrate that the addition of 1,4 cyclohexadiene, able to generate HOO• radicals, restores their antioxidant activity, because of the reducing capability of the HOO• radicals. The antioxidant activity of the oxidized compounds in combination with 1,4-cyclohexadiene is, in some cases, greater than that found for the starting compounds towards the peroxyl radicals. This synergy can be applied to maximize the performances of these new bisphenol neolignans.

Insight into Isolation and Characterization of Phenolic Compounds from Hawthorn (Crataegus pinnatifida Bge.) with Antioxidant, Anti-Acetylcholinesterase, and Neuroprotective Activities

Recent epidemiologic studies have demonstrated a link between the consumption of daily functional fruits rich in phenols and the prevention of disease for neurodegenerative disorders. Hawthorn products are derived from the functional fruit hawthorn, which is rich in phenols and has been used around the world for centuries. In order to explore the phenolic components in hawthorn, the investigation of the ethanol extract led to the separation of five new phenol compounds (1a/1b, 2-4), including one pair of enantiomers (1a/1b), along with seven disclosed analogs (5-11). Their structures were elucidated based on extensive spectroscopic analyses and electronic circular dichroism (ECD). The compounds (1-11) were tested for antioxidant activities by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid) (ABTS), and ferric reducing antioxidant power (FRAP) methods. Apart from that, monomeric compounds 2, 4, and 6 exhibited more potent protective capabilities against H₂O₂ (hydrogen peroxide)-induced SH-SY5Y cells. Meanwhile, electronic analyses were performed using the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) to analyze compounds 2, 4, and 6. Furthermore, compounds (1-11) measured acetylcholinesterase (AChE) inhibitory activities, and 2, 4, and 6 possessed greater AChE inhibitory activity than donepezil. At the same time, molecular docking was used to investigate the possible mechanism of the interaction between active compounds (2, 4, and 6) and AChE.

In Vitro Antioxidant and Prooxidant Activities of Red Raspberry (Rubus idaeus L.) Stem Extracts

Leaves and stems of red raspberry (Rubus idaeus) are used in Lithuanian folk medicine. Healing properties of raspberry are related to the content of bioactive compounds, mainly polyphenols. Extracts of raspberry leaves contained higher total phenolic content (TPC) (1290 mg/L, expressed in gallic acid equivalent) compared to that in extracts of stems or peeled bark (up to 420 mg/L and 598 mg/L, respectively). To find out whether the collection time of herbal material was critical for the properties of the extracts, the stems were collected at different times of the year. TPC in the extracts depended more on extraction conditions rather than on the sampling time. Antioxidant activity of raspberry stem and bark extracts tested by spectrophotometric (DPPH● scavenging) and electrochemical (cyclic and differential pulse voltammetry) assays correlated with TPC. DPPH radical scavenging activity values for stem, leaf, and bark extracts were as follows: ≤1.18 ± 0.07, 1.63 ± 0.10, and ≤1.90 ± 0.04 (mmol/L, TROLOX equivalent), respectively. Assessed electrochemically, hydrogen peroxide-scavenging activity of extracts was independent on TPC. The latter activity was related to the presence of some protein in the extract as revealed by gel electrophoresis. Prooxidant activity of raspberry stem extracts was dependent on solution pH and temperature.

Bioactivity and Chemical Profile of Rubus idaeus L. Leaves Steam-Distillation Extract

The leaves of Rubus idaeus L., a by-product of the fruit food industry, are a known source of bioactive molecules, although the chemical composition has only been partially investigated. The main objective of this study was to examine the biological activities and the chemical composition of the extract of leaves of R. idaeus (RH), obtained by steam distillation (SD). The antioxidant capacity; the total phenolic content (TPC); the cytotoxic activity against tumor cell lines; and the antibacterial activity, in addition to the study of the chemical fingerprinting, carried out by Gas/Chromatography-Mass-Spectrometry (GC/MS) and Headspace (HS)-GC/MS, were established. The extract showed a strong antioxidant capacity and a modest antibacterial activity against two bacterial strains, as well as significant cytotoxic activity against tumor cell lines (Caco-2 and HL60) and being proliferative on healthy cells. Many of the GC-identified volatile molecules (1,8-cineol, β-linalool, geraniol, caryophyllene, τ-muurolol, citral, α-terpineol, 3- carene, α-terpinen-7-al, etc.) can explain most of the biological properties exhibited by the extract of R. idaeus L. The high biological activity of the RH and the high compatibility with the various matrices suggest good prospects for this extract, both in the food and cosmetic fields or in dietary supplements for improving human health.

Investigation of Chemical Composition, Antioxidant Activity, and the Effects of Alfalfa Flavonoids on Growth Performance

The flavonoids were extracted from alfalfa using ethanol assisted with ultrasonic extraction and purified by D101 macroporous resin column chromatography. The chemical composition and content of ethanol elution fractions (EEFs) were assessed by ultrahigh-performance liquid chromatography and hybrid quadrupole time of flight mass spectrometry (UHPLC-Q-TOF-MS) and aluminum nitrate-sodium nitrite-sodium hydroxide colorimetric method. The in vitro antioxidant activity of two EEFs was conducted by scavenging DPPH free radical, and the main antioxidants of 75% EEFs were screened using DPPH-UHPLC. Moreover, the in vivo antioxidant activity of 75% EEFs and the growth performance of broilers were studied. The results showed that the content of 30% and 75% EEFs was 26.20% and 62.57%. Fifteen compounds were identified from 75% EEFs, and five of them were reported in alfalfa for the first time. The scavenging activity of 75% and 30% EEFs (200 μg/mL) against DPPH was 95.51% and 78.85%. The peak area of 5,3',4'-trihydroxyflavone and hyperoside was decreased by 82.69% and 76.04%, which exhibited strong scavenging capacities. The total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-PX) level of three treated groups against the normal control group (NC) fed with basal diet significantly increased by 3.89-24.49%, 0.53-7.39%, and 0.79-11.79%, respectively. While the malondialdehyde (MDA) decreased by 0.47-18.27%. Compared with the NC, the feed to gain ratio (F : G) of three treated groups was lowered by 2.98-16.53% and survival rate of broilers significantly increased. Consequently, 75% EEFs extracted from alfalfa exhibited powerful antioxidant activities and might be a potential feed additive to poultry and livestock.

Investigation of Chemical Composition, Antioxidant Activity, and the Effects of Alfalfa Flavonoids on Growth Performance

The flavonoids were extracted from alfalfa using ethanol assisted with ultrasonic extraction and purified by D101 macroporous resin column chromatography. The chemical composition and content of ethanol elution fractions (EEFs) were assessed by ultrahigh-performance liquid chromatography and hybrid quadrupole time of flight mass spectrometry (UHPLC-Q-TOF-MS) and aluminum nitrate-sodium nitrite-sodium hydroxide colorimetric method. The in vitro antioxidant activity of two EEFs was conducted by scavenging DPPH free radical, and the main antioxidants of 75% EEFs were screened using DPPH-UHPLC. Moreover, the in vivo antioxidant activity of 75% EEFs and the growth performance of broilers were studied. The results showed that the content of 30% and 75% EEFs was 26.20% and 62.57%. Fifteen compounds were identified from 75% EEFs, and five of them were reported in alfalfa for the first time. The scavenging activity of 75% and 30% EEFs (200 μg/mL) against DPPH was 95.51% and 78.85%. The peak area of 5,3′,4′-trihydroxyflavone and hyperoside was decreased by 82.69% and 76.04%, which exhibited strong scavenging capacities. The total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-PX) level of three treated groups against the normal control group (NC) fed with basal diet significantly increased by 3.89-24.49%, 0.53-7.39%, and 0.79-11.79%, respectively. While the malondialdehyde (MDA) decreased by 0.47-18.27%. Compared with the NC, the feed to gain ratio (F : G) of three treated groups was lowered by 2.98-16.53% and survival rate of broilers significantly increased. Consequently, 75% EEFs extracted from alfalfa exhibited powerful antioxidant activities and might be a potential feed additive to poultry and livestock.

Lignans and Neolignans: Plant secondary metabolites as a reservoir of biologically active substances

Lignans and neolignans are plant secondary metabolites derived from the oxidative coupling of phenylpropanoids. Biological activity of these phenolic compounds ranges from antioxidant, antitumor (terminaloside P, IC₅₀ = 10 nM), anti-inflammatory, anti-neurodegenerative (schibitubin B, IC₅₀ = 3.2 nM) and antiviral (patentiflorin A, IC₅₀ = 14-23 nM) to antimicrobial. In addition, it was observed that several members of this group, namely enterolactone and its biochemical precursors also known as phytoestrogens, possess important protective properties. Most of these lignans and neolignans are presented in reasonable amounts in one's diet and thus the protection they provide against the colon and breast cancer, to name a few, is even more important to note. Similarly, neuroprotective properties were observed (schisanwilsonin G, IC₅₀ = 3.2 nM) These structural motives also serve as an important starting point in the development of anticancer drugs. Presumably the most famous members of this family, etoposide and teniposide, synthetic derivatives of podophyllotoxin, are used in the clinical treatment of lymphocytic leukemia, certain brain tumors, and lung tumors already for nearly 20 years. This review describes 413 lignans and neolignans which have been isolated between 2016 and mid-2018 being reported in more than 300 peer-reviewed articles. It covers their source, structure elucidation, and bioactivity. Within the review, the structure-based overview of compounds as well as the bioactivity-based overview of compounds are described.

Multidirectional biological investigation and phytochemical profile of Rubus sanctus and Rubus ibericus

In the present study, the biological properties, including, the enzyme inhibitory and antioxidant activities, as well as, the phytochemical profile of the ethyl acetate, methanol, and water extracts of Rubus sanctus Schreb. and Rubus ibericus Juz. leaves were determined using in vitro bioassays. Wide range of phytochemicals, including, hydroxybenzoic acids, hydroxycinnamic acids, acylquinic acids, ellagitannins, flavonoids, and triterpenoid saponins were determined using UHPLC-ESI/HRMS technique. The ethyl acetate and methanol extracts of the studied Rubus species effectively inhibited acetyl and butyryl cholinesterase. On the other hand, R. sanctus water extract showed low inhibition against α-amylase and prominent inhibitory action against α-glucosidase. Data collected from this study reported the radical scavenging and reducing potential of the studied Rubus species. Investigation of the protective effects of the different extracts of R. sanctus and R. ibericus in experimental model of ulcerative colitis was performed. The extracts were also tested on spontaneous migration of human colon cancer cells (HCT116) in wound healing experimental paradigm. Only R. sanctus methanol extract inhibited spontaneous HCT116 migration in the wound healing test. Our results suggested that R. sanctus and R. ibericus may be potential candidates as sources of biologically-active compounds for the development of nutraceuticals, pharmaceuticals, and/or cosmetics.

Neuroprotective Effects of 1,2-Diarylpropane Type Phenylpropanoid Enantiomers from Red Raspberry against H2O2-Induced Oxidative Stress in Human Neuroblastoma SH-SY5Y Cells

Red raspberry (Rubus idaeus L.) is an edible fruit-producing species belonging to the Rosaceae family. In our search for the health-promoting constituents from this fruit, four pairs of enantiomeric phenylpropanoids (1a/1b-4a/4b), including three new compounds (1a and 2a/2b), were isolated from red raspberry. Their structures were elucidated by a combination of the extensive NMR spectroscopic data analyses, high-resolution electrospray ionization mass spectrometry and comparison between the experimental measurements of electronic circular dichroism (ECD) and calculated ECD spectra by time-dependent density functional theory (TDDFT). In addition, their neuroprotective effects against H₂O₂-induced oxidative stress in human neuroblastoma SH-SY5Y cells were investigated, and the results showed enantioselectivity, in which that 3a exhibited noticeable neuroprotective activity, while its enatiomer 3b exhibited no obvious protective effect. Further study demonstrated that 3a could selectively inhibit the apoptosis induction and reactive oxygen species (ROS) accumulation by enhancing the activity of catalase (CAT) in H₂O₂-treated human neuroblastoma SH-SY5Y cells. These findings shed much light on a better understanding of the neuroprotective effects of these enantiomers and provide new insights into developing better treatment of neurodegenerative diseases in the future.

The neuroprotective and antioxidant profiles of selenium-containing polysaccharides from the fruit of Rosa laevigata

A rapid and effective approach for the extraction and separation of polysaccharides from the title fruit was developed using microwave-assisted aqueous two-phase extraction with a PEG/ammonium sulfate system.