Evaluation of anti-infective potencies of formulated aloin A ointment and aloin A isolated from Aloe barbadensis Miller

Investigations on physiochemical and biomedical properties of Aloe vera - Sterculia gum copolymeric dressings impregnated with antibiotic-anesthetic drugs to enhance wound healing

Recently, various innovative advancements have been made in carbohydrate research to design versatile materials for biomedical applications. The current research focuses on the development of copolymeric hydrogel wound dressings (HWD) using a combination of aloe vera (AV) - sterculia gum (SG) - poly (vinylsulfonic acid) (VSA)-based with the aim to enhancing their efficacy in drug delivery (DD) applications. These hydrogel dressings were encapsulated with levofloxacin and lidocaine to address both microbial infection and pain. Copolymers were characterized by FESEM, SEM, EDS, AFM, 13C NMR, FTIR, XRD, and TGA-DTG analysis. Hydrogel exhibited a fluid absorption capacity of 4.52 ± 0.12 g per gram of polymeric dressing in simulated wound conditions. The hydrogels displayed a sustained release of drugs, demonstrating a non-Fickian diffusion mechanism. Polymer dressings revealed antibacterial, mucoadhesive, antioxidant, biocompatible and non-cytotoxic properties. Additionally, HWD displayed permeability to O2 and water vapour, yet was impermeable to microbial penetration. Overall, the findings of physiological, biochemical and drug delivery properties demonstrated the suitability of materials for wound dressing applications.

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.

Thymol, a Monoterpenoid within Polymeric Iodophor Formulations and Their Antimicrobial Activities

Antimicrobial resistance (AMR) poses an emanating threat to humanity's future. The effectiveness of commonly used antibiotics against microbial infections is declining at an alarming rate. As a result, morbidity and mortality rates are soaring, particularly among immunocompromised populations. Exploring alternative solutions, such as medicinal plants and iodine, shows promise in combating resistant pathogens. Such antimicrobials could effectively inhibit microbial proliferation through synergistic combinations. In our study, we prepared a formulation consisting of Aloe barbadensis Miller (AV), Thymol, iodine (I2), and polyvinylpyrrolidone (PVP). Various analytical methods including SEM/EDS, UV-vis, Raman, FTIR, and XRD were carried out to verify the purity, composition, and morphology of AV-PVP-Thymol-I2. We evaluated the inhibitory effects of this formulation against 10 selected reference strains using impregnated sterile discs, surgical sutures, gauze bandages, surgical face masks, and KN95 masks. The antimicrobial properties of AV-PVP-Thymol-I2 were assessed through disc diffusion methods against 10 reference strains in comparison with two common antibiotics. The 25-month-old formulation exhibited slightly lower inhibitory zones, indicating changes in the sustained-iodine-release reservoir. Our findings confirm AV-PVP-Thymol-I2 as a potent antifungal and antibacterial agent against the reference strains, demonstrating particularly strong inhibitory action on surgical sutures, cotton bandages, and face masks. These results enable the potential use of the formulation AV-PVP-Thymol-I2 as a promising antimicrobial agent against wound infections and as a spray-on contact-killing agent.

Green Synthesized Polymeric Iodophors with Thyme as Antimicrobial Agents

Antimicrobial resistance (AMR) is a growing concern for the future of mankind. Common antibiotics fail in the treatment of microbial infections at an alarming rate. Morbidity and mortality rates increase, especially among immune-compromised populations. Medicinal plants and their essential oils, as well as iodine could be potential solutions against resistant pathogens. These natural antimicrobials abate microbial proliferation, especially in synergistic combinations. We performed a simple, one-pot synthesis to prepare our formulation with polyvinylpyrrolidone (PVP)-complexed iodine (I2), Thymus Vulgaris L. (Thyme), and Aloe Barbadensis Miller (AV). SEM/EDS, UV-vis, Raman, FTIR, and XRD analyses verified the purity, composition, and morphology of AV-PVP-Thyme-I2. We investigated the inhibitory action of the bio-formulation AV-PVP-Thyme-I2 against 10 selected reference pathogens on impregnated sterile discs, surgical sutures, cotton gauze bandages, surgical face masks, and KN95 masks. The antimicrobial properties of AV-PVP-Thyme-I2 were studied by disc diffusion methods and compared with those of the antibiotics gentamycin and nystatin. The results confirm AV-PVP-Thyme-I2 as a strong antifungal and antibacterial agent against the majority of the tested microorganisms with excellent results on cotton bandages and face masks. After storing AV-PVP-Thyme-I2 for 18 months, the inhibitory action was augmented compared to the fresh formulation. Consequently, we suggest AV-PVP-Thyme-I2 as an antimicrobial agent against wound infections and a spray-on contact killing agent.

Evaluation of extracts from Sida acuta, Phyllanthus amarus, Parkia biglobosa and their herbal ointment for therapeutic and biological activities

Herbal extracts are a well-known source of therapeutically important bioactive chemicals since they are widely available, relatively inexpensive, and have fewer adverse effects. The three plants' leaves have been used to treat a variety of illnesses in Ghana, including skin conditions and wound infections. Their effectiveness as an ointment in treating the aforementioned illnesses has not yet been shown, though. The extracts were made into an ointment with polyethylene glycol (PEG), and both the ointment and the raw extracts were examined for in vitro antibacterial activity. The three (3) chosen bacterial isolates were subjected to potential activities of the plant extracts from different extractants. The minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) values for the plant extracts were both low. The herbal ointment made with Sida acuta extract from both extractants showed significantly different activity (P < 0.05), against the test pathogens when compared to the reference medication (Madecassol®). However, the activities of formulated herbal ointment from both P. amarus and P. biglobosa extracts were comparable at higher concentrations to the standard drug used. Notably, both plant extracts and extract-PEG manufactured ointments exhibit significant in vitro efficacy against the disease-causing bacterial species. The current study is the first in-depth account of Parkia species with regard to an examination of herbal ointments made from leaves extract obtained utilizing solvents such as water and ethanol. Our research findings have important implications for the pharmaceutical industry in terms of providing a suitable, workable, and alternative supply of bioactive compounds and anti-infective agents.

Antibacterial activities of anthraquinones: structure-activity relationships and action mechanisms

With the increasing prevalence of untreatable infections caused by antibiotic-resistant bacteria, the discovery of new drugs from natural products has become a hot research topic. The antibacterial activity of anthraquinones widely distributed in traditional Chinese medicine has attracted much attention. Herein, the structure and activity relationships (SARs) of anthraquinones as bacteriostatic agents are reviewed and elucidated. The substituents of anthraquinone and its derivatives are closely related to their antibacterial activities. The stronger the polarity of anthraquinone substituents is, the more potent the antibacterial effects appear. The presence of hydroxyl groups is not necessary for the antibacterial activity of hydroxyanthraquinone derivatives. Substitution of di-isopentenyl groups can improve the antibacterial activity of anthraquinone derivatives. The rigid plane structure of anthraquinone lowers its water solubility and results in the reduced activity. Meanwhile, the antibacterial mechanisms of anthraquinone and its analogs are explored, mainly including biofilm formation inhibition, destruction of the cell wall, endotoxin inhibition, inhibition of nucleic acid and protein synthesis, and blockage of energy metabolism and other substances.

Combination therapy: synergism among three plant extracts against selected pathogens

OBJECTIVE

The synergism among extracts of Senna alata, Ricinus communis, and Lannea barteri, and their anti-infective activities were investigated. The data collected for the antimicrobial activity of the extracts combinations were interpreted to be one of the following categories: synergy; indifferent; additive; or antagonistic. The interpretation was made based on the fractional inhibitory concentration index (FICI) results. FICI of ≤ 0.5 indicates synergism, > 0.5 to 1 indicates additive effects, > 1 to ≤ 4 indifference, and > 4 is considered to be antagonism.

RESULTS

Compared with the data of the individual extracts, the MIC values of the extract-extract combinations against all strains of the tested microorganisms were significantly lower, ranging from 0.97 to 1.17, 0.97 to 4.69, 0.50 to 1.17, 1.17 to 3.12 and 2.34 to 4.69 mg/mL for Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia and Candida albicans respectively. L. bateri aqueous-S. alata ethanol extracts and S. alata aqueous-R. cummunis ethanol extracts combinations showed a synergy effect against all the test microorganisms. The other combinations exhibited at least one additive effect. Neither antagonism nor indifference activity was observed. This study validates the relevance of combining these plants in treating infections by traditional medicine practitioners.

Preparation of Aloe-Emodin Microcapsules and Its Effect on Antibacterial and Optical Properties of Water-Based Coating

With the development of science and technology, the function of waterborne coatings has been advanced to a higher standard, which requires researchers to innovate and expand the research on them. Aloe-emodin is a natural material with antibacterial properties. Applying its antibacterial effect to the coating can enrich its function and meet the diversified needs of consumers. In this study, the urea-formaldehyde resin was used as the wall material and the aloe-emodin as the core material to prepare the microcapsules. The coating rate, yield, and morphology of the microcapsules were characterized. Through an orthogonal experiment and a single factor experiment, the optimization scheme of microcapsule preparation was explored. The results indicated that the optimum preparation process of aloe-emodin microcapsules was as follows: the mass ratio of core material to wall material was 1:15, the molar ratio of urea to formaldehyde was 1:1.2, the temperature of microencapsulation was 50 °C, and the stirring speed of microencapsulation was 600 rpm. On this basis, the aloe-emodin microcapsules with 0%, 1.0%, 3.0%, 6.0%, 9.0%, and 12.0% contents were added to the waterborne coating to prepare the paint films, and their influence on the antibacterial and optical properties of the waterborne paint films was explored. The results demonstrated that the aloe-emodin microcapsules had antibacterial activity. When the content was 6.0%, the comprehensive performance of the film was better. The antibacterial rate of the film against Escherichia coli was 68.1%, and against Staphylococcus aureus it was 60.7%. The color difference of the film was 59.93, and the glossiness at 60° was 7.8%. In this study, the microcapsules that can improve the antibacterial performance of water-based coatings were prepared, which can expand the application of water-based coatings and provide a reference for the study of the functionalization of water-based coatings.

The current status of old traditional medicine introduced from Persia to China

Traditional Chinese medicine (TCM) includes over ten thousand herbal medicines, some of which were introduced from outside countries and territories. The Silk Road enabled the exchange of merchandise such as teas, silks, carpets, and medicines between the East and West of the Eurasia continent. During this time, the ‘Compendium of Materia Medica’ (CMM) was composed by a traditional medicine practitioner, Shizhen Li (1,518–1,593) of the Ming Dynasty. This epoch-making masterpiece collected knowledge of traditional medical materials and treatments in China from the 16th century and before in utmost detail, including the origin where a material was obtained. Of 1892 medical materials from the CMM, 46 came from Persia (now Iran). In this study, the basic information of these 46 materials, including the time of introduction, the medicinal value in TCM theory, together with the current status of these medicines in China and Iran, are summarized. It is found that 20 herbs and four stones out of the 46 materials are registered as medicinal materials in the latest China Pharmacopoeia. Now most of these herbs and stones are distributed in China or replacements are available but saffron, ferula, myrrh, and olibanum are still highly dependent on imports. This study may contribute to the further development, exchange, and internationalization of traditional medicine of various backgrounds in the world, given the barriers of transportation and language are largely eased in nowadays.

Characterization of the metabolism of aloin A/B and aloesin in rats by using ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

Aloin A/B and aloesin are the major bioactive constituents in the Aloe vera, with diverse pharmacological activities, including anti-bacterial, anti-tumour, anti-inflammatory and intestinal regulation. However, the in vivo metabolism of aloin A/B and aloesin are still unclear. In this study, the metabolic processes of aloin A/B and aloesin in rats were investigated using the ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) and MetaboLynx^TM software with Mass defect filter (MDF) technique. Based on the proposed method, the prototype component of three compounds were all detected in the rat plasma, urine and feces. Meanwhile, 25 aloin A/B metabolites (6 phase I, 3 phase II, 16 phase I combined with phase II) and 3 aloesin metabolites (2 phase I and 1 phase II) were detected in rats after oral administration of aloin A, aloin B and aloesin, and the main biotransformation reactions were hydroxylation, oxidation, methylation, acetylation, and glucuronidation. In addition, Aloin A and aloin B can be transformed into each other in vivo and the metabolic profiles of aloin A and aloin B were identical. These results provide essential data for further pharmaceutical researches and clinical application of aloin A/B and aloesin.

Antimicrobial Biomaterial on Sutures, Bandages and Face Masks with Potential for Infection Control

Antimicrobial resistance (AMR) is a challenge for the survival of the human race. The steady rise of resistant microorganisms against the common antimicrobials results in increased morbidity and mortality rates. Iodine and a plethora of plant secondary metabolites inhibit microbial proliferation. Antiseptic iodophors and many phytochemicals are unaffected by AMR. Surgical site and wound infections can be prevented or treated by utilizing such compounds on sutures and bandages. Coating surgical face masks with these antimicrobials can reduce microbial infections and attenuate their burden on the environment by re-use. The facile combination of Aloe Vera Barbadensis Miller (AV), Trans-cinnamic acid (TCA) and Iodine (I₂) encapsulated in a polyvinylpyrrolidone (PVP) matrix seems a promising alternative to common antimicrobials. The AV-PVP-TCA-I₂ formulation was impregnated into sterile discs, medical gauze bandages, surgical sutures and face masks. Morphology, purity and composition were confirmed by several analytical methods. Antimicrobial activity of AV-PVP-TCA-I₂ was investigated by disc diffusion methods against ten microbial strains in comparison to gentamycin and nystatin. AV-PVP-TCA-I₂ showed excellent antifungal and strong to intermediate antibacterial activities against most of the selected pathogens, especially in bandages and face masks. The title compound has potential use for prevention or treatment of surgical site and wound infections. Coating disposable face masks with AV-PVP-TCA-I₂ may be a sustainable solution for their re-use and waste management.

The potential health benefits of aloin from genus Aloe

The Aloe species is known for its medicinal and cosmetic properties. Aloin is an active ingredient found in the leaves of medicinal plants of the genus Aloe. Aloin has attracted considerable interest for its antiinflammatory, anticancer, antibacterial, and antioxidant activities. However, since its clinical application is restricted by its unclear mechanism of action, a deeper understanding of its pharmacological activity is required. This review provides an overview of current pharmacological and toxicological studies published in English from February 2000 to August 2021. Herein, we summarized the sources and potential health benefits of aloin from a clinical application perspective to guide for further studies on the sources of aloin, aimed at efficiently increasing aloin production. Importantly, the function and mechanism of action of aloin remain unclarified. In future research, it is necessary to develop new approaches for studying the pharmacological molecular mechanisms underlying the activity of this compound against various diseases.

Caribbean Women's Health and Transnational Ethnobotany

Caribbean Women's Health and Transnational Ethnobotany. Immigrants from the Dominican Republic (DR) and Haiti are among the top foreign-born communities in New York City (NYC). As people migrate to new countries, they bring their ethnomedical beliefs and practices, and adapt their plant pharmacopoeias. Haiti and the DR share a flora on the island of Hispaniola. In NYC, the flora is limited to what is available in the city. We selected plants for future laboratory research based on ethnobotanical data from two surveys among Dominicans in the DR and NYC, and a Haitian literature review. In both Dominican datasets, gynecological infections were the top women's health condition treated with plants. We identified 10 species for this purpose reported by Dominicans that are also known medicines in Haitian culture, although not yet documented for women's health. Plants for gynecological infections potentially cause dysbiosis of the vaginal microbiota, and may increase rather than prevent disease. There is a public health need to assess traditional medicines for their ability to inhibit pathogenic bacteria, while causing minimal disruption to the vaginal flora. Several species are known antibacterials, but remain to be tested for their efficacy. These results also provide a foundation for a planned ethnobotanical survey among NYC Haitian women.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12231-021-09526-3.

Anthraquinones from Aloe spp. inhibit Cryptococcus neoformans sensu stricto: effects against growing and mature biofilms

This study aimed to evaluate the in vitro effect of aloe emodin, barbaloin and chrysophanol on growing and mature biofilms of Cryptococcus neoformans sensu stricto. The compounds were added at the moment of inducing biofilm growth or after growth for 72 h to evaluate their effects on growing and mature biofilms, respectively. Then, biofilm biomass was evaluated by crystal violet staining and metabolic activity by the XTT reduction assay. Morphological alterations were also evaluated by laser scanning confocal microscopy. Aloe emodin and barbaloin affected growing biofilms and disrupted mature biofilms, reducing metabolic activity by > 60% and biomass by > 70%. Chrysophanol only inhibited mature biofilms, but to a lesser extent. In conclusion, anthraquinones, especially aloe emodin and barbaloin, show a relevant effect against growing and mature biofilms of C. neoformans sensu stricto.

Facile Synthesis of Bio-Antimicrobials with "Smart" Triiodides

Multi-drug resistant pathogens are a rising danger for the future of mankind. Iodine (I₂) is a centuries-old microbicide, but leads to skin discoloration, irritation, and uncontrolled iodine release. Plants rich in phytochemicals have a long history in basic health care. Aloe Vera Barbadensis Miller (AV) and Salvia officinalis L. (Sage) are effectively utilized against different ailments. Previously, we investigated the antimicrobial activities of smart triiodides and iodinated AV hybrids. In this work, we combined iodine with Sage extracts and pure AV gel with polyvinylpyrrolidone (PVP) as an encapsulating and stabilizing agent. Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-visible spectroscopy (UV-Vis), Surface-Enhanced Raman Spectroscopy (SERS), microstructural analysis by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-Ray-Diffraction (XRD) analysis verified the composition of AV-PVP-Sage-I₂. Antimicrobial properties were investigated by disc diffusion method against 10 reference microbial strains in comparison to gentamicin and nystatin. We impregnated surgical sutures with our biohybrid and tested their inhibitory effects. AV-PVP-Sage-I₂ showed excellent to intermediate antimicrobial activity in discs and sutures. The iodine within the polymeric biomaterial AV-PVP-Sage-I₂ and the synergistic action of the two plant extracts enhanced the microbial inhibition. Our compound has potential for use as an antifungal agent, disinfectant and coating material on sutures to prevent surgical site infections.

African Herbal Medicines: Adverse Effects and Cytotoxic Potentials with Different Therapeutic Applications

The African continent is naturally endowed with various plant species with nutritional and medicinal benefits. About 80% of the people in developing countries rely on folk medicines to treat different diseases because of indigenous knowledge, availability, and cost-effectiveness. Extensive research studies have been conducted on the medicinal uses of African plants, however, the therapeutic potentials of some of these plants has remained unexploited. Over the years, several studies have revealed that some of these African floras are promising candidates for the development of novel drugs. Despite the plethora of studies on medicinal plant research in Africa, there is still little scientific data supporting the folkloric claims of these plants. Besides, safety in the use of folk medicines has been a major public health concern over the year. Therefore, it has become mandatory that relevant authority should take measures in safeguarding the populace on the use of herbal mixtures. Thus, the present review extracted relevant information from different scientific databases and highlighted some problems associated with folk medicines, adverse effects on reproductive systems, issue about safety due to the toxicity of some plants and their toxicity effects with potential therapeutic benefits are discussed.

Facile Synthesis of Antimicrobial Aloe Vera-"Smart" Triiodide-PVP Biomaterials

Antibiotic resistance is an eminent threat for the survival of mankind. Nosocomial infections caused by multidrug resistant microorganisms are a reason for morbidity and mortality worldwide. Plant-based antimicrobial agents are based on synergistic mechanisms which prevent resistance and have been used for centuries against ailments. We suggest the use of cost-effective, eco-friendly Aloe Vera Barbadensis Miller (AV)-iodine biomaterials as a new generation of antimicrobial agents. In a facile, one-pot synthesis, we encapsulated fresh AV gel with polyvinylpyrrolidone (PVP) as a stabilizing agent and incorporated iodine moieties in the form of iodine (I2) and sodium iodide (NaI) into the polymer matrix. Ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), x-ray diffraction (XRD), microstructural analysis by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) verified the composition of AV-PVP-I2, AV-PVP-I2-NaI. AV, AV-PVP, AV-PVP-I2, AV-PVP-I2-NaI, and AV-PVP-NaI were tested in-vitro by disc diffusion assay and dip-coated on polyglycolic acid (PGA) sutures against ten microbial reference strains. All the tested pathogens were more susceptible towards AV-PVP-I2 due to the inclusion of "smart" triiodides with halogen bonding in vitro and on dip-coated sutures. The biocomplexes AV-PVP-I2, AV-PVP-I2-NaI showed remarkable antimicrobial properties. "Smart" biohybrids with triiodide inclusions have excellent antifungal and promising antimicrobial activities, with potential use against surgical site infections (SSI) and as disinfecting agents.