Medicinal importance, pharmacological activities, and analytical aspects of aloin: A concise report

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.

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.

Modulatory Properties of Aloe secundiflora's Methanolic Extracts on Targeted Genes in Colorectal Cancer Management

Colon tumors have a very complicated and poorly understood pathogenesis. Plant-based organic compounds might provide a novel source for cancer treatment with a sufficient novel mode of action. The objective of this study was to analyze and evaluate the efficacy of Aloe secundiflora's (AS) methanolic extracts on the expression of CASPS9, 5-LOX, Bcl2, Bcl-xL, and COX-2 in colorectal cancer (CRC) management. Caco-2 cell lines were used in the experimental study. In the serial exhaustive extraction (SEE) method, methanol was utilized as the extraction solvent. Upon treatment of CASPS9 with the methanolic extracts, the expression of the genes was progressively upregulated, thus, dose-dependently increasing the rate of apoptosis. On the other hand, the expressions of 5-LOX, Bcl2, and Bcl-xL were variably downregulated in a dose-dependent manner. This is a unique novel study that evaluated the effects of AS methanolic extracts in vitro on CRC cell lines using different dosage concentrations. We, therefore, recommend the utilization of AS and the application of methanol as the extraction solvent of choice for maximum modulatory benefits in CRC management. In addition, we suggest research on the specific metabolites in AS involved in the modulatory pathways that suppress the development of CRC and potential metastases.

Medicinal Characteristics of Withania somnifera L. in Colorectal Cancer Management

Research into tumorigenic pathways can aid in the development of more efficient cancer therapies and provide insight into the physiological regulatory mechanisms employed by rapidly proliferating cancer cells. Due to the severe side effects of cancer chemotherapeutic medications, plant chemicals and their analogues are now explored more frequently for the treatment and prevention of colorectal cancer (CRC), opening the stage for new phytotherapeutic strategies that are considered effective and safe substitutes. Our study aimed to evaluate the medicinal properties of Withania somnifera L. and its safety applications in CRC management. Important databases were rigorously searched for relevant literature, and only 82 full-text publications matched the inclusion requirements from a massive collection of 10,002 titles and abstracts. W. somnifera L. contains a high concentration of active plant-based compounds. The pharmacological activity of the plant from our study has been demonstrated to exert antiproliferation, upregulation of apoptosis, decrease in oxidative stress, downregulation of cyclooxygenase-2 (COX-2), induction of targeted cytotoxic effects on cancerous cells, and exertion of both antiangiogenesis and antimigratory effects. We advise further research before recommending W. somnifera L. for clinical use to identify the optimal concentrations required to elicit beneficial effects in CRC management in humans, singly or in combination.

Pharmacotherapeutic Potential of Aloe secundiflora against Colorectal Cancer Growth and Proliferation

Aloe species are widespread and diverse in African ecosystems, and this commonly correlates to their habitual use as reservoirs of herbal medicine. The side effects associated with chemotherapy and the development of antimicrobial resistance to empirically used antimicrobial drugs are substantial, paving the way for novel phytotherapeutic approaches. This comprehensive study aimed to evaluate and present Aloe secundiflora (A. secundiflora) as a compelling alternative with potential benefits in colorectal cancer (CRC) treatment. Important databases were systematically searched for relevant literature, and out of a large collection of 6421 titles and abstracts, only 68 full-text articles met the inclusion criteria. A. secundiflora possesses an abundant presence of bioactive phytoconstituents in the leaves and roots, including anthraquinones, naphthoquinones, phenols, alkaloids, saponins, tannins, and flavonoids, among others. These metabolites have proven diverse efficacy in inhibiting cancer growth. The presence of innumerable biomolecules in A. secundiflora signifies the beneficial effects of incorporating the plant as a potential anti-CRC agent. Nonetheless, we recommend further research to determine the optimal concentrations necessary to elicit beneficial effects in the management of CRC. Furthermore, they should be investigated as potential raw ingredients for making conventional medications.

Tyrosinase Inhibitors Naturally Present in Plants and Synthetic Modifications of These Natural Products as Anti-Melanogenic Agents: A Review

Tyrosinase is a key enzyme target to design new chemical ligands against melanogenesis. In the current review, different chemical derivatives are explored which have been used as anti-melanogenic compounds. These are different chemical compounds naturally present in plants and semi-synthetic and synthetic compounds inspired by these natural products, such as kojic acid produced by several species of fungi; arbutin-a glycosylated hydroquinone extracted from the bearberry plant; vanillin-a phenolic aldehyde extracted from the vanilla bean, etc. After enzyme inhibition screening, various chemical compounds showed different therapeutic effects as tyrosinase inhibitors with different values of the inhibition constant and IC₅₀. We show how appropriately designed scaffolds inspired by the structures of natural compounds are used to develop novel synthetic inhibitors. We review the results of numerous studies, which could lead to the development of effective anti-tyrosinase agents with increased efficiency and safety in the near future, with many applications in the food, pharmaceutical and cosmetics industries.

The Triprenylated Anthranoid Ferruginin A, a Promising Scaffold for the Development of Novel Antibiotics against Gram-Positive Bacteria

In today's post-antibiotic era, the search for new antimicrobial compounds is of major importance and nature represents one of the primary sources of bioactive molecules. In this work, through a cheminformatics approach, we clustered an in-house library of natural products and their derivatives based on a combination of fingerprints and substructure search. We identified the prenylated emodine-type anthranoid ferruginin A as a novel antimicrobial compound. We tested its ability to inhibit and kill a panel of Gram-positive and Gram-negative bacteria, and compared its activity with that of two analogues, vismione B and ferruanthrone. Furthermore, the capability of these three anthranoids to disrupt staphylococcal biofilm was investigated, as well as their effect on the viability of human keratinocytes. Ferruginin A showed a potent activity against both the planktonic and biofilm forms of Gram-positive bacteria (i.e., Staphylococcus aureus and S. epidermidis) and had the best therapeutic index compared to vismione B and ferruanthrone. In conclusion, ferruginin A represents a promising scaffold for the further development of valuable antimicrobial agents.

Antiglycation Activity and HT-29 Cellular Uptake of Aloe-Emodin, Aloin, and Aloe arborescens Leaf Extracts

Aloe arborescens is a relevant species largely used in traditional medicine of several countries. In particular, the decoction of leaves is prepared for various medicinal purposes including antidiabetic care. The aim of this research was the study of the antiglycation activity of two A. arborescens leaf extracts and isolated compounds: aloin and aloe-emodin. These phytoconstituents were quantitatively assessed in methanolic and hydroalcoholic extracts using high performance liquid chromatography (HPLC) analysis. In addition, the total phenolic and flavonoid contents were detected. In order to study their potential use in diabetic conditions, the antiglycation and antiradical properties of the two extracts and aloin and aloe-emodin were investigated by means of bovine serum albumin (BSA) and 1,1-diphenyl-2-picryl-hydrazil (DPPH) assays; further, their cytotoxicity in HT-29 human colon adenocarcinoma cells was evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay. Furthermore, the ability of aloin and aloe-emodin to permeate the cellular membranes of HT-29 cells was determined in order to estimate their potential in vivo absorption. This assessment indicated that aloe-emodin can substantially pass through cell membranes (~20%), whereas aloin did not permeate into HT-29 cells. Overall, the data show that both the methanolic and the hydroalcoholic A. arborescens extracts determine significant inhibition of glycation and free-radical persistence, without any cytotoxic activity. The data also show that the antiglycation and the antiradical activities of aloin and aloe-emodin are lower than those of the two extracts. In relation to the permeability study, only aloe-emodin is able to cross HT-29 cellular membranes, showing the attitude to pass through the intestinal layer. Overall, the present data surely support the traditional use of A. arborescens leaf extracts against hyperglycemic conditions, while aloin and aloe-emodin as potential drugs need further study.