Extraction of bio-active compounds from Ethiopian plant material Rumex abyssinicus (mekmeko) root—A study on kinetics, optimization, antioxidant and antibacterial activity

Silver Nanoparticle Synthesis by Rumex vesicarius Extract and Its Applicability against Foodborne Pathogens

The consumption of foods polluted with different foodborne pathogens such as fungus, viruses, and bacteria is considered a serious cause of foodborne disease in both humans and animals. Multidrug-resistant foodborne pathogens (MRFP) cause morbidity, death, and substantial economic loss, as well as prolonged hospitalization. This study reports on the use of aqueous Rumex leaf extract (ARLE) in the synthesis of silver nanoparticles (ARLE-AgNPs) with versatile biological activities. The synthesized ARLE-AgNPs had spherical shapes with smooth surfaces and an average hydrodynamic size of 27 nm. ARLE-AgNPs inhibited the growth of Escherichia coli ATCC25721, Pseudomonas aeruginosa ATCC27843, Streptococcus gordonii ATCC49716, Enterococcus faecalis ATCC700813, and Staphylococcus aureus ATCC4342. The ARLE-AgNPs were more active against Escherichia coli ATCC25721 than other harmful bacterial strains (26 ± 3 mm). The zone of inhibition for antibacterial activity ranged between 18 ± 3 mm and 26 ± 3 mm in diameter. The nanoparticles' MIC values varied from 5.19 µg/mL to 61 µg/mL, while their MBC values ranged from 46 µg/mL to 119 µg/mL. The nanoparticles that were created had antioxidant potential. The cytotoxic activity was tested using normal fibroblast cell lines (L-929), and the enhanced IC50 value (764.3 ± 3.9 g/mL) demonstrated good biological compatibility. These nanoparticles could be evolved into new antibacterial compounds for MRFP prevention.

Evaluation of the Antidiabetic Activity of Hydromethanolic Roots Extracts of Rumex abyssinicus Jacq: (Polygonaceae) in Swiss Albino Mice

Introduction

Diabetes Mellitus isa chronic metabolic disorder that required long-lasting treatment. In Ethiopian traditional medicine practices, abundant plants have been used for the treatment of diabetes mellitus for a long period. The root of Rumex abyssinicus is employed for the treatment of diabetes mellitus by Ethiopians. This study aimed to investigate the antidiabetic activity of the crude extract of Rumex abyssinicus root in Swiss albino mice.

Methods

Cold maceration technique and hydro methanolic (80% methanol) solvent with occasionally shaking were employed during the crude extraction processes. To evaluate the antidiabetic activity of the crude extract, normoglycemic, glucose-loaded, and streptozotocin-induced diabetic models were used. In each model, the overnight fasted mice were randomly divided into five groups for normoglycemic and glucose-loaded models as a negative control, positive control, and three tested groups, whereas, in streptozotocin-induced diabetic models, the mice were grouped into six groups like one diabetic and one normal negative control groups, three diabetic tested groups, and one diabetic positive group. Each group comprised six mice. For all models, the tested groups received the crude extract at 100, 200, and 400 mg/kg doses, both diabetic and nondiabetic negative control groups received 10 ml/kg distilled water, and positive groups received 5 mg/kg glibenclamide.

Results

The crude extract of the plant did not show any sign of toxicity up to 2000 mg/kg dose. In normoglycemic and oral glucose tolerance tests, the crude extract significantly (p < 0.01) reduced the blood glucose level at 200 and 400 mg/kg doses. In the streptozotocin-induced diabetes models, a significant effect was observed at all tested doses.

Conclusion

The finding of this study revealed that the crude extract of the plant owned antidiabetic activity and supports the traditional use of Rumex abyssinicus root for the treatment of diabetes mellitus.

Antibacterial, antifungal and antioxidant activities of whole plant chemical constituents of Rumex abyssinicus

Background

Antibiotic resistance has contributed to the burden of infectious diseases both in the hospital and community setting, and represents a great threat to public health. Previous studies have revealed the role of reactive oxygen species as intermediate mediators of tissue damage, following antibiotherapies, indicating the need of associating antioxidants to these treatments. Therefore, the present work was designed to study the antibacterial, antifungal and antioxidant activities of extracts and compounds from Rumex abyssinicus Jacq. (Polygonaceae), as well as to investigate the antibacterial mechanisms of action of the most effective agents.

Methods

The plant extracts were prepared by maceration in organic solvents followed by column chromatography of the EtOAc fraction and purification of different fractions which led to the isolation and characterization of pure compounds. The antimicrobial activities of the extracts/compounds and their combinations with ciprofloxacin and fluconazole were evaluated using the broth microdilution method by determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC). The effects of the extracts on the bacterial cell membrane and microbial respiratory chain dehydrogenase enzyme activity were determined by spectrophotometric methods. Antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and gallic acid equivalent antioxidant capacity (GAEAC) assays.

Results

Chrysophanol (1), physcion (2), Ergosta-6,22-diene-3,5,8-triol (3), emodin (4), 6-hydroxyemodin (citreorosein) (5), chrysophanein (6) and physcionin (7) were isolated from EtOAc fraction of R. abyssinicus and displayed different degrees of antimicrobial activities (MIC = 8–256 μg/mL). The MeOH extract and compounds 2 and 4 exhibited synergistic effects with ciprofloxacin and fluconazole. Compounds 1, 2 and the combined mixture of 6 + 7 displayed the highest antioxidant activity (GAEAC = 83.38–106.03 μg/mL).

Conclusion

R. abyssinicus is a potential source of antibacterial, antifungal and antioxidant agents. The antibacterial mechanisms of action of the MeOH extract and compound 2 are due to disruption of the cytoplasmic membrane and inhibition of the microbial respiratory chain dehydrogenase enzyme activity. To the best of our knowledge, this is the first report of test samples and ciprofloxacin / fluconazole association against MDR strains. The observed activity of the isolated compounds against bacteria and fungi including MDR strains deserves further exploration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03325-y.

A Glimpse into the Extraction Methods of Active Compounds from Plants

Naturally active compounds are usually contained inside plants and materials thereof. Thus, the extraction of the active compounds from plants needs appropriate extraction methods. The commonly employed extraction methods are mostly based on solid-liquid extraction. Frequently used conventional extraction methods such as maceration, heat-assisted extraction, Soxhlet extraction, and hydrodistillation are often criticized for large solvent consumption and long extraction times. Therefore, many advanced extraction methods incorporating various technologies such as ultrasound, microwaves, high pressure, high voltage, enzyme hydrolysis, innovative solvent systems, adsorption, and mechanical forces have been studied. These advanced extraction methods are often better than conventional methods in terms of higher yields, higher selectivity, lower solvent consumption, shorter processing time, better energy efficiency, and potential to avoid organic solvents. They are usually designed to be greener, more sustainable, and environment friendly. In this review, we have critically described recently developed extraction methods pertaining to obtaining active compounds from plants and materials thereof. Main factors that affect the extraction performances are tuned, and extraction methods are chosen in line with the properties of targeted active compounds or the objectives of extraction. The review also highlights the advancements in extraction procedures by using combinations of extraction methods to obtain high overall yields or high purity extracts.

In vivo Hepatoprotective and in vitro Radical Scavenging Activities of Extracts of Rumex abyssinicus Jacq. Rhizome

BACKGROUND

Liver diseases contribute a prominent global burden of mortality and morbidity. The current therapies of liver diseases have numerous limitations including severe adverse effects. This denotes that new more effective, safer, and cheaper drugs are required and medicinal plants used in traditional medicines often offer ideal opportunities. Accordingly, the present study aimed to evaluate the in vivo hepatoprotective and in vitro radical scavenging activities of dried rhizome extracts of Rumex abyssinicus (R. abyssinicus), which is traditionally claimed to provide hepatoprotection.

MATERIALS AND METHODS

Hepatoprotective activity of extracts was evaluated using carbon tetrachloride (CCl4)-induced liver injury in mice. Pre- and post-treatment models were employed to test the effect of the extracts and silymarin (standard drug). Serum biochemical markers and liver histopathology were used as parameters to evaluate hepatoprotective activities whereas in vitro radical scavenging activity was tested by 2, 2-diphenyl-2-picrylhydrazyl hydrate (DPPH) assay.

RESULTS AND CONCLUSION

Oral administration of CCl4 (1 ml/kg) significantly (P<0.001) raised the serum levels of liver enzyme markers compared to the normal control group. Pre-treatment with 125, 250, and 500 mg/kg of R. abyssinicus extract reduced the serum level of CCl4-induced rise in liver enzyme markers with the highest reduction observed at a dose of 500 mg/kg. Likewise, in the post-treatment model, the crude extract and butanol fraction at dose 500 mg/kg reduced levels of liver enzymes. Histopathological examinations revealed lesser liver damage of extract-treated mice compared to the toxic (CCl4-treated) controls. The in vitro radical scavenging activity of the different extracts showed concentration-dependent radical scavenging activity. Thus, the results of this study may justify the traditional use of the plant as a hepatoprotective agent.

CONCLUSION

Results of serum biochemical markers and histopathological examinations of CCl4-induced mice models, in the present study, show the hepatoprotective potential of extracts from the rhizome of R. abyssinicus.

Enhanced extraction of hydroxytyrosol, maslinic acid and oleanolic acid from olive pomace: Process parameters, kinetics and thermodynamics, and greenness assessment

Three techniques of ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and solvent extraction (SE) were used for enhancing the hydroxytyrosol (HT), maslinic acid (MA) and oleanolic acid (OA) extraction from olive pomace, being evaluated and compared through process parameters, kinetics and thermodynamics, plus greenness assessment analysis. Results showed that UAE yielded the maximum compounds due to a strong cavitation effect and the strongest mass and heat transfer efficiency involving the kinetic constants (h, C_e and K) and thermodynamic parameters (△H, △S and △G). Additionally, the optimal extraction conditions were acquired: ethanol concentration of 90%, extraction temperature of 50 °C, extraction time of 5 min, liquid to solid ratio of 30 mL/g, ultrasound intensity of 135.6 W/cm², and ultrasound frequency of 60 kHz. UAE was confirmed as an effective and greener technique with the lowest E factor, energy consumption and carbon emission during the extraction process of bioactive compounds from olive pomace.