Extraction of Aloesin from Aloe vera Rind Using Alternative Green Solvents: Process Optimization and Biological Activity Assessment

Study of the Incorporation of Gel and Aloe vera Peel Extract in a Polymer Matrix Based on Polyvinylpyrrolidone

The development of dressings based on electrospun membranes with polymers and plant extracts is an interesting approach to skin regeneration, providing elements to prevent contamination and a matrix that accelerates the healing process. We developed a membrane composed of polyvinylpyrrolidone (PVP), gel and Aloe vera peel extract via the electrospinning technique. Additionally, an optimal ratio of PVP/Av gel/Av skin extract was determined to facilitate membrane formation. Electrospun membranes were obtained with fiber diameters of 1403 ± 57.4 nm for the PVP and 189.2 ± 11.4 nm for PVP/Av gel/Av peel extract, confirming that the use of extracts generally reduced the fiber diameter. The incorporation of gel and peel extract of Aloe vera into the electrospun membrane was analyzed via FTIR and UV-Vis spectroscopies. FTIR revealed the presence of functional groups associated with phenolic compounds such as aloin, aloe-emodin, emodin and aloesin, which was confirmed by UV-Vis, revealing absorption bands corresponding to aloin, phenols and carbonyl groups. This finding provides evidence of the effective integration and prevalence of bioactive compounds of a phenolic and polysaccharide nature from the gel and the Av skin extract in the electrospun fibers, resulting in an advanced membrane that could improve and accelerate the healing process and protect the wound from bacterial infections.

Aloe vera-An Extensive Review Focused on Recent Studies

Since ancient times, Aloe vera L. (AV) has attracted scientific interest because of its multiple cosmetic and medicinal properties, attributable to compounds present in leaves and other parts of the plant. The collected literature data show that AV and its products have a beneficial influence on human health, both by topical and oral use, as juice or an extract. Several scientific studies demonstrated the numerous biological activities of AV, including, for instance, antiviral, antimicrobial, antitumor, and antifungal. Moreover, its important antidepressant activity in relation to several diseases, including skin disorders (psoriasis, acne, and so on) and prediabetes, is a growing field of research. This comprehensive review intends to present the most significant and recent studies regarding the plethora of AV's biological activities and an in-depth analysis exploring the component/s responsible for them. Moreover, its morphology and chemical composition are described, along with some studies regarding the single components of AV available in commerce. Finally, valorization studies and a discussion about the metabolism and toxicological aspects of this "Wonder Plant" are reported.

Fragmentation Patterns of Phenolic C-Glycosides in Mass Spectrometry Analysis

BACKGROUND

Many phenolic C-glycosides possess nutritional benefits and pharmacological efficacies. However, the MS/MS fragmentation pattern of phenolic C-glycosides analysis is understudied. This paper aims to determine the MS/MS fragmentation patterns of phenolic C-glycosides.

METHOD

Ten compounds with different sugar moieties, aglycones, and substitutes were analyzed to determine the impact of these structural features on MS/MS fragmentation using UPLC-QTOF-MS analysis.

RESULTS

The results showed that water loss followed by RDA reaction and alpha cleavage in the C-C bonded sugar moieties are the major fragmentation pathways. Additionally, the sugar cleavage was not affected by the skeleton and the substitute of the aglycones. These results suggested that the fragmentation patterns of phenolic C-glycosides differ from those in the O-glycosides, where the O-C glycosidic bond is the most cleavage-liable bond in MS/MS analysis.

CONCLUSIONS

These MS/MS fragmentation patterns can be used for the identification of C-glycosides from dietary components and herbal medicine as well as developing robust methods using MRM methods to quantify C-glycosides.

New opportunities and perspectives on biosynthesis and bioactivities of secondary metabolites from Aloe vera

Historically, the genus Aloe has been an indispensable part of both traditional and modern medicine. Decades of intensive research have unveiled the major bioactive secondary metabolites of this plant. Recent pandemic outbreaks have revitalized curiosity in aloe metabolites, as they have proven pharmacokinetic profiles and repurposable chemical space. However, the structural complexity of these metabolites has hindered scientific advances in the chemical synthesis of these compounds. Multi-omics research interventions have transformed aloe research by providing insights into the biosynthesis of many of these compounds, for example, aloesone, aloenin, noreugenin, aloin, saponins, and carotenoids. Here, we summarize the biological activities of major aloe secondary metabolites with a focus on their mechanism of action. We also highlight the recent advances in decoding the aloe metabolite biosynthetic pathways and enzymatic machinery linked with these pathways. Proof-of-concept studies on in vitro, whole-cell, and microbial synthesis of aloe compounds have also been briefed. Research initiatives on the structural modification of various aloe metabolites to expand their chemical space and activity are detailed. Further, the technological limitations, patent status, and prospects of aloe secondary metabolites in biomedicine have been discussed.

The Utilization of an Aloe Vera Rind By-Product: Deep Eutectic Solvents as Eco-Friendly and Recyclable Extraction Media of Polyphenolic Compounds

In this study, an optimized environmentally friendly procedure was employed to enhance the sustainable utilization of phenolic antioxidants derived from aloe vera rind by-products. The procedure involved the application of ultrasound-assisted extraction (UAE) in combination with deep eutectic solvents (DESs). Eleven different DESs and three conventional solvents were employed as extraction media for polyphenolic compounds. Choline chloride-citric acid (ChCl-CA) was selected as the most suitable extractant, considering its extraction efficiency in relation to the total phenolic content. The operating conditions of UAE were optimized and modeled by the use of response surface methodology in order to maximize the yield of total phenolics and antioxidant capacity. The optimal operational parameters for the UAE procedure were determined to be 16.5 min, 74% (v/v) DES in water, and a solvent-to-solid ratio equal to 192. HPLC analysis, which was performed on the optimum extract, revealed significant levels of phenolics present in the aloe rind. Efficient recovery of the extracted antioxidants was obtained by the use of solid-phase extraction (SPE) and polyamide cartridges. The ChCl-CA DES exhibited excellent recycling capability with a yield of over 90% through SPE. Finally, the greenness of the method was evaluated using the green AGREE and AGREEprep metrics. The results highlighted the sustainability and the greenness of the proposed extraction procedure for the aloe by-product.

Nano-platform Strategies of Herbal Components for the Management of Rheumatoid Arthritis: A Review on the Battle for Next-Generation Formulations

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that initially affects small joints and then spreads to the bigger joints. It also affects other organs of the body such as lungs, eyes, kidneys, heart, and skin. In RA, there is destruction of cartilage and joints, and ligaments and tendons become brittle. Damage to the joints leads to abnormalities and bone degradation, which may be quite painful for the patient.

METHOD

The nano-carriers such as liposomes, phytosomes, nanoparticles, microcapsules, and niosomes are developed to deliver the encapsulated phytoconstituents to targeted sites for the better management of RA.

RESULTS

The phytoconstituents loaded nano-carriers have been used in order to increase bioavailability, stability and reduce the dose of an active compound. In one study, the curcumin-loaded phytosomes increase the bioavailability of curcumin and also provides relief from RA symptoms. The drug-loaded nano-carriers are the better option for the management of RA.

CONCLUSION

In conclusion, there are many anti-arthritic herbal and synthetic medicine available in the market that are currently used in the treatment of RA. However, chronic use of these medications may result in a variety of side effects. Because therapy for RA is frequently necessary for the rest of ones life. The use of natural products may be a better option for RA management. These phytoconstituents, however, have several disadvantages, including limited bioavailability, low stability, and the need for a greater dosage. These problems can be rectified by using nano-technology.

Natural Product Aloesin Significantly Inhibits Spore Germination and Appressorium Formation in Magnaporthe oryzae

This study aims to determine the effects of the natural product aloesin against Magnaporthe oryzae. The results exposed that aloesin had a high inhibitory effect on appressorium formation (the EC50 value was 175.26 μg/mL). Microscopic examination revealed that 92.30 ± 4.26% of M. oryzae spores could be broken down by 625.00 μg/mL of aloesin, and the formation rate of appressoria was 4.74 ± 1.00% after 12 h. M. oryzae mycelial growth was weaker than that on the control. The enzyme activity analysis results indicated that aloesin inhibited the activities of polyketolase (PKS), laccase (LAC), and chain-shortening catalytic enzyme (Aayg1), which are key enzymes in melanin synthesis. The inhibition rate by aloesin of PKS, LAC, and Aayg1 activity was 32.51%, 33.04%, and 43.38%, respectively. The proteomic analysis showed that actin expression was downregulated at 175.62 μg/mL of aloesin, which could reduce actin bundle formation and prevent the polar growth of hyphae in M. oryzae. This is the first report showing that aloesin effectively inhibits conidia morphology and appressorium formation in M. oryzae.

Phenolic profile, in vitro antimicrobial and in vivo diuretic effects of endemic wild thyme Thymus comosus Heuff ex. Griseb. (Lamiaceae) from Romania

Thymus comosus Heuff ex. Griseb. (Lamiaceae) is a wild thyme species endemic for Romanian Carpathian areas, frequently collected as substitute for collective herbal product Serpylli herba, cited as antibacterial and diuretic remedy in traditional medicine. The present study aimed to evaluate the in vivo diuretic effect and in vitro antimicrobial properties of three herbal preparations (infusion-TCI, tincture-TCT and an hydroethanolic extract prepared through an optimized ultrasound-assisted method-OpTC) obtained from the aerial parts of T. comosus Heuff ex. Griseb, also evaluating their comprehensive phenolic profile. In vivo diuretic effect was tested using Wistar rats treated orally with each herbal preparation (125 and 250 mg/kg dispersed in 25 ml/kg isotonic saline solution) and quantified based on cumulative urine output (ml), diuretic action and diuretic activity. Additionally, sodium and potassium excretion were monitored using a potentiometric method with selective electrodes. In vitro antibacterial and antifungal activities were assessed using p-iodonitrotetrazolium chloride assay against six bacterial strains and six fungal strains by monitoring minimum inhibitory concentration (MICs), minimum bactericidal concentrations (MBCs) and minimum fungicidal concentrations (MFCs). Finally, phenolic profile of the aforementioned herbal extracts was evaluated using an ultra-high-pressure liquid chromatography (UHPLC) coupled with high-resolution mass spectrometry (HRMS) method to check the impact of the different preparations on the most abundant and significant compounds. All the extracts exerted a mild diuretic action, TCT and OpTC inducing the most intense diuretic effect. Both herbal preparations produced a statistically significant, dose-dependent and gradual increase of the urine output, the effect being more intense at 24 h (6.63-7.13 ml/24 h). Potentiometric evaluation of urine samples collected from treated rats revealed a clear and mild natriuretic and kaliuretic effect after the administration. In terms of antimicrobial activity, E. coli (MIC-0.38 mg/ml), B. cereus (MIC-0.75 mg/ml)), Penicillium funiculosum and P. verrucosum var. cyclopium (MIC-0.19 mg/ml) showed the greater sensitivity to the tested extracts, respectively. UHPLC-HRMS screening showed that the bioactive potential of T. comosus herbal preparations was likely related to the higher amounts of phenolic acids (including rosmarinic acid), flavonoids (mainly flavones and derivatives) and other phenolics (such as different isomers of salvianolic acids) in their composition. The obtained results support the ethnopharmacological evidence regarding the mild diuretic and antibacterial potentials of the endemic wild thyme T. comosus, this study being the first one that assessed the aforementioned bioactivities for this species.

Chlorella vulgaris Extract-Decorated Gold Nanoparticle Hybridized Antimicrobial Hydrogel as a Potential Dressing

This study reports a novel design of a moisturizing and antimicrobial hydrogel with injectable properties, using a green solvent (glycerol) as a cross-linking agent and gold nanoparticle reduced by Chlorella extract as an antimicrobial approach. We have synthesized gold nanoparticles (AuNPs) with environmentally friendly and bio-safe properties using Chlorella aqueous extracts (AuNPs@Chlorella). Characterization of the nanoparticles by ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), Raman spectrum, and transmission electron microscope (TEM) confirmed that spherical AuNPs with the particle size of 10-20 nm were successfully synthesized. An analysis of the enhancement of the stability of gelatin hydrogels by the addition of glycerol and AuNPs was performed by rheometry. In addition, we also used Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) to confirm the good antibacterial activity. Therefore, the as-prepared gelatin-glycerol hydrogels containing AuNPs@Chlorella are most likely promising alternatives for wound healing dressings.

Phytochemical Analysis, Antibacterial and Antibiofilm Activities of Aloe vera Aqueous Extract against Selected Resistant Gram-Negative Bacteria Involved in Urinary Tract Infections

In bacterial infections, including urinary tract infections (UTIs), the gap between the development of new antimicrobials and antimicrobial resistance is dramatically increasing, especially in Gram-negative (Gram–) bacteria. All healthy products that can be used per se or that may be sources of antibacterial compounds should be considered in the fight against this major public health threat. In the present study, the phytochemical composition of Aloe vera extract was investigated by HPLC–MS/MS, and we further evaluated its antibacterial and antibiofilm formation activity against selected resistant Gram– bacteria involved in UTIs, namely, Achromobacter xylosoxidans 4892, Citrobacter freundii 426, Escherichia coli 1449, Klebsiella oxytoca 3003, Moraxella catarrhalis 4222, Morganella morganii 1543, Pseudomonas aeruginosa 3057, and a reference strain E. coli ATCC 25922. Inhibition zones (IZs) of the extract were determined using the well diffusion method, minimum inhibitory (MIC), and bactericidal (MBC) concentration by the two-fold serial microdilution assay, and antibiofilm formation activity by the crystal violet attachment assay. Aloe-emodin and its derivatives were the major constituent (75.74%) of A. vera extract, the most important of them being aloesin (30.22%), aloe-emodin-diglucoside (12.58%), and 2′-p-methoxycoumaroylaloeresin B (9.64%). The minerals found in the extract were sulfur (S), silicon (Si), chlorine (Cl), potassium (K), and bromine (Br). Except for the clinical strain E. coli 1449, which was totally non-susceptible, A. vera demonstrated noteworthy antibacterial activity with MIC and MBC values ranging from 0.625 to 5 mg/mL and 5 to 10 mg/mL, respectively. A. vera also demonstrated dose-dependent antibacterial effects, and the reference strain E. coli ATCC 25922 was the most susceptible with MIC = 0.625 and IZ = 19 mm at 20 mg/mL. The antibiofilm formation potential of A. vera extract was strong at 2MIC and MIC (93–100% of biofilm formation inhibition), moderate at MIC/2 (32–41%), weak at MIC/4 (14–21%), and nil at MIC/8.

Optimized ultrasound-assisted extraction of phenolic compounds from Thymus comosus Heuff. ex Griseb. et Schenk (wild thyme) and their bioactive potential

An optimized ultrasound-assisted extractive method was developed to obtain a polyphenol-enriched extract from the aerial parts of Thymus comosus Heuff. ex Griseb. et Schenk. Optimization process was conducted based on Design of Experiment (DoE) principles, determining the influence of three independent variables (time, ultrasound amplitude, ethanol concentration) on the total phenolic content of the extract (dependent variable). Additionally, the phenolic composition of the extract was characterized through UHPLC-HRMS, revealing beside the most abundant flavonoid-type compounds the presence of salvianolic acids C, D and L in high amounts. Phytochemical profile of the extract was correlated with its antioxidant activity (tested through five complementary assays) and enzyme-inhibitory potential, showing important antiglucosidase and anticholinesterase effects. Overall, it was concluded that the developed method is suitable for obtaining a good recovery of both phenolic and non-phenolic compounds from Thymus comosus aerial parts, and their presence in the optimized extract is responsible for its pharmacological potential.