Isolation and identification of new anthraquinones from Rhamnus alaternus L and evaluation of their free radical scavenging activity

Recent research on the physicochemical properties and biological activities of quinones and their practical applications: a comprehensive review

Quinones represent a class of crude organic compounds ubiquitously distributed in nature. Their distinctive quinone-type structure confers upon them unique properties and applications. Quinones demonstrate significant biological activities, including antioxidant, antimicrobial, and antitumor properties. Additionally, they demonstrate noteworthy physicochemical characteristics, including excellent dyeing properties and stability. Given their diverse qualities, quinones hold significant promise for applications in industrial manufacturing, healthcare, and food production, thus garnering considerable attention in recent years. While there is a growing body of research on quinones, the existing literature falls short of providing a comprehensive review encompassing recent advancements in this field along with established knowledge. This paper offers a comprehensive review of research progress for quinones, encompassing structural classification, source synthesis, extraction methods, properties, functions, and specific applications. It serves as a reference and theoretical foundation for the further development and utilization of quinones.

Antibacterial and Antioxidant Compounds from the Root Extract of Aloe debrana

This study was conducted to isolate and identify the chemical compounds from the roots of Aloe debrana (L.) and evaluate their antioxidant and antibacterial activities. From the acetone (99.5%) extract of the roots of this plant, four anthraquinones, such as chrysophanol (1), asphodeline (2), aloesaponarin I (5), and laccaic acid D-methyl ester (6), and a new catechol derivative, 5-allyl-3-methoxybenzene-1,2-diol (3), were isolated and elucidated by different chromatographic and spectroscopic methods together with linoleic acid (4), respectively. Compounds 2, 3, and 4 were reported here for the first time from this plant and compound 3 from the genus Aloe. The compounds were evaluated for their antioxidant activity using H2O2 and DPPH assays and bactericidal activity against S. aureus and E. coli. Compounds 3 and 6 showed highest antioxidant activities with IC50 values of 19.38 ± 0.64 and 32.81 ± 0.78 μg/mL in DPPH, and 28.52 ± 1.08 and 27.31 ± 1.46 μg/mL in H2O2, respectively. The isolated compounds also demonstrated considerable activity towards S. aureus. Among these compounds, compound 3 exhibited the highest activity (91.20 ± 0.12% and 9.14 ± 0.93 mm at 1.0 mg/mL) against this bacterium. The overall results suggest that the isolated compounds may be considered as potential sources of the bioactive agents to be used in the pharmacological, food, and other industries. Moreover, their high sensitivity against S. aureus may also support the use of A. debrana plant in the traditional medicine to treat wounds. Therefore, the isolated compounds are responsible for medicinal properties of this plant.

Anthraquinones from Rhamnus alaternus L.: A Phytocosmetic Ingredient with Photoprotective and Antimelanogenesis Properties

The purpose of the present work was to develop a phytocosmetic sunscreen emulsion with antioxidant activity and an anti-melanogenic effect, containing an anthraquinone-enriched extract of Rhamnus alaternus (A.E.). Our findings demonstrated that A.E. decreased the levels of reactive oxygen species, DNA damage, and malondialdehyde induced by UVA in human keratinocytes and melanocytes. Furthermore, the calculated SPF value in vitro of the cream containing A.E. was 14.26±0.152. Later, it was shown that A.E. extract had an inhibitory effect on the amount of melanin. This extract could also reduce B16F10 intracellular tyrosinase activity. Besides, docking studies were carried out to provide a logical justification for the anti-tyrosinase potential. The findings showed that, A.E. may provide protection against UVA-induced oxidative stress and could be thought of as a viable treatment for hyperpigmentation disorders.

Preparation, Characterization, and Evaluation of Physcion Nanoparticles for Enhanced Oral Bioavailability: An Attempt to Improve Its Antioxidant and Anticancer Potential

This study aims to enhance the dissolution rate of a poorly water-soluble drug physcion by producing its nanoparticles (NPs) using an antisolvent precipitation with a syringe pump (APSP) method and to assess its antioxidant and cytotoxic potential. The NPs were prepared using a simple and cost-effective APSP method and subsequently characterized by different analytical techniques including dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray powder diffractometry (XRD). They were also subjected to solubility and dissolution studies, and different parameters such as dissolution efficiency (DE), mean dissolution time (MDT), and difference (f1) and similarity factors (f2) were determined. Furthermore, physcion and its NPs were investigated for antioxidant and cytotoxic effects using various in vitro assays. SEM and DLS analysis indicated that the average size of physcion NPs was 110 and 195 ± 5.6 nm, respectively. The average ζ-potential and polydispersibility index (PDI) of the prepared NPs were -22.5 mV and 0.18, respectively, showing excellent dispersibility. XRD confirmed the amorphous nature of physcion NPs. The solubility and dissolution rates of NPs were significantly higher than those of the original powder. The antioxidant potential studied by the (DPPH), FRAP, and H2O2 assays was greater for physcion NPs than that for the raw powder. The IC50 values of physcion NPs against the aforementioned models were 57.56, 22.30, and 22.68 μg/mL, respectively. Likewise, the cytotoxic potential investigated through the MTT assay showed that physcion NPs were more cytotoxic to cancer cell lines A549 (IC50 4.12 μg/mL), HepG2 (IC50 2.84 μg/mL), and MDA-MB-231 (IC50 2.97 μg/mL), while it had less effect on HPAEpiC (IC50 8.68 μg/mL) and HRPTEpiC (IC50 10.71 μg/mL) normal human epithelial cells. These findings have proved that the APSP method successfully produced physcion NPs with enhanced solubility, dissolution rate, and antioxidant and cytotoxic activities.

Development and Validation of a SPE-HPLC Method for Quantification of Rhein, Emodin, Chrysophanol and Physcion in Rhamnus petiolaris Boiss. & Balansa

Anthraquinones exhibit a significant group of natural and synthetic quinone derivatives because of their biological activities and industrial applications. Rhamnaceae is one of the families known to contain different kinds of anthraquinones. In this study, it was aimed to quantify rhein, emodin, chrysophanol and physcion in fruits of Rhamnus petiolaris Boiss. & Balansa belonging to Rhamnaceae by solid phase extraction and high performance liquid chromatography with ultraviolet detection. The anthraquinones were separated using a C18 analytical column. Gradient elution was performed using a mobile phase consisted of 0.1% o-phosphoric acid solution and methanol. Analytes were detected at 254 nm. Calibration curves were prepared in the range of 0.25-5.00 μg/mL for rhein, chrysophanol, physcion, 1.00-50.00 μg/mL for emodin. Limits of detection and quantification were between 0.07-0.11 and 0.20-0.34 μg/mL, respectively. Relative standard deviations were ≤ 5.78% in repeatability and intermediate precision studies. Accuracy was determined as relative mean error (8.17-12.06%). Extraction was achieved by maceration with acetone and ethanol, followed by hydrophilic-lipophilic balance solid phase extraction. Recoveries were between 96.2 and 109.6%. The developed and validated method was successfully performed to quantify rhein, emodin, chrysophanol and physcion in R. petiolaris fruit extracts. Only physcion was not detected above limit of detection.

Plant anthraquinones: Classification, distribution, biosynthesis, and regulation

Anthraquinones are polycyclic compounds with an unsaturated diketone structure (quinoid moiety). As important secondary metabolites of plants, anthraquinones play an important role in the response of many biological processes and environmental factors. Anthraquinones are common in the human diet and have a variety of biological activities including anticancer, antibacterial, and antioxidant activities that reduce disease risk. The biological activity of anthraquinones depends on the substitution pattern of their hydroxyl groups on the anthraquinone ring structure. However, there is still a lack of systematic summary on the distribution, classification, and biosynthesis of plant anthraquinones. Therefore, this paper systematically reviews the research progress of the distribution, classification, biosynthesis, and regulation of plant anthraquinones. Additionally, we discuss future opportunities in anthraquinone research, including biotechnology, therapeutic products, and dietary anthraquinones.

Quercetin-3-O-β-D-glucopyranoside-rich fraction demonstrated efficacy against infectious, secretory, and osmotic models of diarrhoeal rats

BACKGROUND

The prevalence of diarrhoea remains high despite efforts by governments and NGOs to reverse trend. This study investigated the antidiarrhoeal activity and mechanism of Spondias mombin leaf fraction rich in quercetin-3-O-β-D-glucopyranoside (Q3G-RF) because of the acclaimed therapeutic efficacy. Secretory, osmotic, and infectious diarrhoea models using castor oil, magnesium sulphate, and Shigella flexneri respectively were evaluated at the doses of 100, 200, and 400 mg/kg in Wistar rats. Enteropathy was induced with castor oil and magnesium sulphate, while gastrointestinal motility was determined with charcoal meal.

RESULTS

Findings showed no mortality after 14 days of experimental period and no significant changes in behaviour, food, and water consumption. Relative to control, Q3G-RF inhibited the three models of diarrhoea, enteropathy, and gastrointestinal motility; bacterial colonies were reduced by Q3G-RF, while it improved the relative body weight of the animals. Q3G-RF also increased the intestinal concentration/activity of glucose, total protein, and Na⁺-K⁺ ATPase but reduced the concentration of TNF-α, PGE₂, IL-1β, nitric oxide, Na⁺, K⁺, and Cl^- in the diarrhoeal models. The intestinal fluid level of K⁺, Na⁺, and Cl^- was significantly decreased by Q3G-RF in the enteropathy model. Length of the small intestine in the motility model was also increased by Q3G-RF, while peristaltic index and inhibition of peristalsis were reduced.

CONCLUSION

Overall, quercetin-3-O-β-D-glucopyranoside from Spondias mombin leaves demonstrated efficacy against infectious, secretory, and osmotic form of diarrhoeal and further justified its traditional use in the treatment of diarrhoea due to its antimotility, antisecretory, and antimicrobial properties by mechanism related to enhanced Na⁺-K⁺ ATPase, repressed nitric oxide, and suppressed prostaglandins.

Insight into the Progress on Natural Dyes: Sources, Structural Features, Health Effects, Challenges, and Potential

(1) Background: Dyes play an important role in food, medicine, textile, and other industries, which make human life more colorful. With the increasing demand for food safety, the development of natural dyes becomes more and more attractive. (2) Methods: The literature was searched using the electronic databases PubMed, Web of Science, and SciFinder and this scoping review was carried out following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). (3) Results: 248 articles were included in this review. This review summarizes the research progress on natural dyes in the last ten years. According to structural features, natural dyes mainly include carotenoids, polyphenols, porphyrins, and alkaloids, and some of the newest dyes are summarized. Some pharmacological activities of carotenoids, anthocyanin, curcumin, and betalains in the last 10 years are summarized, and the biological effects of dyes regarding illumination conditions. The disadvantages of natural dyes, including sources, cost, stability, and poor bioavailability, limit their application. Here, some feasible strategies (potential resources, biotechnology, new extraction and separation strategies, strategies for improving stability) are described, which will contribute to the development and utilization of natural dyes. (4) Conclusion: Natural dyes show health benefits and potential in food additives. However, it is necessary for natural dyes to pass toxicity tests and quality tests and receive many regulatory approvals before their final entry into the market as food colorants or as drugs.

Evaluation of Anticancer Potential of Flavones from Rhamnus alaternus against B16F10 Melanoma Cells

Melanoma has become an important health problem and new treatment have become an imperative medical need. Therefore, the finding and identification of natural product with less toxic effects, capable of promoting melanoma cell death have become an important goal of research in oncotherapy. In this study, we want to investigate the anticancer activity of an enriched total oligomers flavonoids (TOF) extract of R. alaternus in melanoma cells. First, TOF was exhibited to be rich in flavones. We revealed that this extract reduced proliferation and increased of sub-G1 and S phase cells built-up in B16-F10 cells in a dose-related manner. Moreover, In Vivo, TOF reduced tumor volume and weight with percentages of inhibition of 92.4% and 92.9%, respectively. R. alaternus was also found to be effective in reducing the level of pro-inflammatory cytokine IL-6 during metastasis. Level of TH1 cytokine, such as IL-2, was significantly enhanced by TOF treatment. Indeed, the histological examination of the tumor revealed the absence of mitoses and the presence of numerous melanin pigmented macrophage cells in the R. alaternus extract-treated group that could be explained by the induction of macrophage activation and by the arrest of the cell cycle in the Sub-G1 and S phases.

Bioguided Isolation of Active Compounds from Rhamnus alaternus against Methicillin-Resistant Staphylococcus aureus (MRSA) and Panton-Valentine Leucocidin Positive Strains (MSSA-PVL)

Despite intensified efforts to develop an effective antibiotic, S. aureus is still a major cause of mortality and morbidity worldwide. The multidrug resistance of bacteria has considerably increased the difficulties of scientific research and the concomitant emergence of resistance is to be expected. In this study we have investigated the in vitro activity of 15 ethanol extracts prepared from Moroccan medicinal plants traditionally used for treatment of skin infections. Among the tested species I. viscosa, C. oxyacantha, R. tinctorum, A. herba alba, and B. hispanica showed moderate anti-staphylococcal activity. However, R. alaternus showed promising growth-inhibitory effects against specific pathogenic bacteria especially methicillin-susceptible Staphylococcus aureus Panton-Valentine leucocidin positive (MSSA-PVL) and methicillin-resistant S. aureus (MRSA). The bioguided fractionation of this plant using successive chromatographic separations followed by nuclear magnetic resonance (NMR) and mass spectrometry (MS) including EIMS and HREIMS analysis yielded the emodin (1) and kaempferol (2). Emodin being the most active with MICs ranging between 15.62 and 1.95 µg/mL and showing higher activity against the tested strains in comparison with the crude extract, its mechanism of action and the structure-activity relationship were interestingly discussed. The active compound has not displayed toxicity toward murine macrophage cells. The results obtained in the current study support the traditional uses of R. alaternus and suggest that this species could be a good source for the development of new anti-staphylococcal agents.

Radical Scavenging Activity of Natural Anthraquinones: a Theoretical Insight

Anthraquinones (ANQs) isolated from Paederia plants are known to have antidiarrheal, antitussive, anthelmintic, analgesic, anti-inflammatory, antihyperlipidemic, antihyperglycaemic, and antimicrobial activities. The antioxidant properties were also noted but not confirmed thus far. In this study, the superoxide and hydroperoxide radical scavenging activities of six ANQs were evaluated using a computational approach. The results suggest that the ANQs exhibit low HOO• antiradical activity in all environments, including the gas phase (k < 102 M-1 s-1). In contrast, the ANQs might exert excellent O2 •- radical scavenging activity, particularly in aqueous solution. The rate constants of the superoxide anion scavenging in water (at pH = 7.4) range from 3.42 × 106 to 3.70 × 108 M-1 s-1. Compared with typical antioxidants such as ascorbic acid and quercetin, the superoxide anion scavenging activity of ANQs is significantly higher. Thus, the ANQs are promising O2 •- radical scavengers in polar media.

Rhamnusalaternus Plant: Extraction of Bioactive Fractions and Evaluation of Their Pharmacological and Phytochemical Properties

Rhamnus alaternus, is a wild-growing shrub, belonging to the Rhamnaceae family. Widely distributed in the Mediterranean basin, R. alaternus is used in the usual medicine in numerous countries, mostly Tunisia, Algeria, Morocco, Spain, France, Italy, and Croatia. A large number of disorders-including dermatological complications, diabetes, hepatitis, and goiter problems-can be treated by the various parts of R. alaternus (i.e., roots, bark, berries, and leaves). Several bioactive compounds were isolated from R. alaternus, including flavonoids, anthocyanins, and anthraquinones, and showed several effects such as antioxidant, antihyperlipidemic, antigenotoxic, antimutagenic, antimicrobial, and antiproliferative. This review summarizes the updated information concerning the botanical description, distribution, extraction processes applied on R. alaternus, and its ethnopharmacology, toxicity, phytochemistry, and pharmacological effects.

Extraction, isolation, characterization and antimicrobial activities of non-extractable polyphenols from pomegranate peel

Non-extractable polyphenols (NEPPs) in pomegranate peel were released by acid hydrolysis followed by extraction using ethyl acetate (EtOAc). Ten NEPPs were identified in the hydrolysate using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Six compounds were then isolated from the EtOAc extracts whose structures were identified as β-sitosterol-3-O-glycoside (1), β-sitosterol (2), ursolic acid (3), corosolic acid (4), asiatic acid (5) and arjunolic acid (6) using a wide range of spectroscopic analyses. Compounds 4-6 were isolated for the first time from pomegranate peel. Antimicrobial experiments revealed that compound 3 and 5 showed significant antimicrobial activity against a range of pathogens, particularly compound 5 which exhibited selective inhibitive activity towards Staphylococcus aureus with a minimum inhibitory concentration (MIC) of 16 μg/ml. The present study has provided new insights into the composition of bound chemicals in pomegranate peel and laid a foundation for improving its further processing and utilization.

Preventive Effects of Anthraquinones Isolated from an Endophytic Fungus, Colletotrichum sp. JS-0367 in Tumor Necrosis Factor-α-Stimulated Damage of Human Dermal Fibroblasts

Reactive oxygen species (ROS) are a major causative factor of inflammatory responses and extracellular matrix degradation. ROS also cause skin aging and diverse cutaneous lesions. Therefore, antioxidants that inhibit the generation of ROS may be beneficial in the relief of skin aging and diseases. We investigated the anti-skin aging effect of anthraquinones from cultures of Colletotrichum sp., an endophytic fungus isolated from Morus alba L. using human dermal fibroblasts (HDFs). We preferentially evaluated the preventive effects of anti-oxidative anthraquinones (1, 4) against the generation of ROS, nitric oxide (NO), and prostaglandins-E₂ (PGE₂). Among them, 1,3-dihydroxy-2,8-dimethoxy-6-methylanthraquinone (1) suppressed the generation of ROS, NO, and PGE₂ in tumor necrosis factor-alpha (TNF-α)-stimulated HDFs. Compound 1 reversed the TNF-induced increase in matrix metalloproteinase (MMP)-1 and a decrease in procollagen I α1 (COLIA1). It also suppressed inducible NO synthase, cyclooxygenase-2, interleukin (IL)-1β, IL-6, and IL-8, which upregulate inflammatory reactions. Mechanistically, compound 1 suppressed nuclear factor-κB, activator protein 1, and mitogen-activated protein kinases in TNF-α-stimulated HDFs. These results suggest that compound 1 may be beneficial for improving skin aging and diverse cutaneous lesions.

Antiviral and Antinematodal potentials of chitosan: Review

For many years, chemical pesticides have been performed to control different pests and diseases and this may be due to their broad spectrum of action, easy of application and the relatively low cost. But these chemicals have environmental risks, thus alternative control agents are needed. Chitosan is one of the novel suggested solutions to reduce the economic losses associated with chemical pesticides. Chitosan is naturally-occurring compound, as well as safe and biodegradable which obtained from certain natural sources. Chitosan have unique properties which help to control viruses, bacteria, fungi, insects, plant nematodes and other pests locally and systemically.