Phenolic Compounds Profiling and Their Antioxidant Capacity in the Peel, Pulp, and Seed of Australian Grown Avocado

Hass Avocado (Persea americana Mill) Peel Extract Reveals Antimicrobial and Antioxidant Properties against Verticillium theobromae, Colletotrichum musae, and Aspergillus niger Pathogens Affecting Musa acuminata Colla Species, in Ecuador

The utilization of agroindustrial residues, such as avocado peel, as a source of bioactive compounds with antioxidant properties has garnered significant attention. In this study, we investigated the antioxidant potential using the DPPH (2,2-diphenyl-1-picrylhydrazyl) and ORAC (oxygen radical absorbance capacity) methods, along with the antimicrobial activity of phenolic compounds extracted from Hass avocado peel. These soluble polyphenols were quantified and identified using high-performance liquid chromatography (HPLC). The research focused on their effects against three fungal pathogens, Verticillium theobromae, Colletotrichum musae, and Aspergillus niger, which significantly impact banana crops, an essential agricultural commodity in Ecuador. The results have revealed that the application of 80% ethanol as an organic solvent led to increased soluble polyphenol content compared to 96% ethanol. Extraction time significantly influenced the phenolic content, with the highest values obtained at 90 min. Interestingly, despite substantial mycelial growth observed across all extract concentrations, the antifungal effect varied among the pathogens. Specifically, V. theobromae exhibited the highest sensitivity, while C. musae and A. niger were less affected. These results underscore the importance of considering both antioxidant and antimicrobial properties when evaluating natural extracts for potential applications in plant disease management.

Microbial dynamics and quality characteristics of spontaneously fermented salamis produced by replacing pork fat with avocado pulp

The aim of this study was to develop a novel and healthier fermented meat product by replacing pork fat with avocado pulp (AVP) during salami production. Experimental salamis were produced under laboratory conditions by substituting pork fat with AVP partially (10-AVP) and totally (20-AVP), while control salamis (CTR) remained AVP-free. The microbial composition of control and experimental salamis was assessed using a combined culture-dependent and -independent approach. Over a 20-days ripening period, lactic acid bacteria, coagulase-negative staphylococci, and yeasts dominated the microbial community, with approximate levels of 9.0, 7.0 and 6.0 log CFU/g, respectively. Illumina technology identified 26 taxonomic groups, with leuconostocs being the predominant group across all trials [constituting 31.26-59.12 % of relative abundance (RA)]. Gas Chromatography-Mass Spectrometry (GC-MS) analysis revealed changes in fatty acid composition and volatile organic compounds due to the substitution of pork fat with AVP. Specifically, monounsaturated fatty acids and terpene compounds increased, while saturated fatty acids and lipid oxidation products decreased. Although AVP influenced the sensory characteristics of the salamis, the highest overall satisfaction ratings were observed for the 10-AVP salamis. Consequently, substituting pork fat with AVP emerges as a viable strategy for producing healthier salamis and diversifying the meat product portfolio.

Ameliorative effect of aqueous avocado seed extract against chromium-induced oxidative stress and cellular damage in rabbit kidney

The accumulation of chromium in renal tissues promotes the generation of reactive oxygen species (ROS), leading to oxidative stress, genomic and cellular harm, and ultimately necrotic and apoptotic cell death induced by free radicals. Hence, the utilization of antioxidant phytochemicals becomes crucial for cellular defense against oxidative damage. This study endeavors to explore the potential protective effects of an aqueous avocado seed extract (ASE) on rabbit kidneys exposed to chromium-induced damage. Fifteen adult rabbits were distributed into three groups: Group 1 was kept as the control. The second and third groups received a daily dose of K2Cr2O7 (5 mg/kg) intraperitoneally for 2 weeks. While the third group was given an oral dose of ASE (400 mg/kg). In rabbits administered with Cr (VI), kidney homogenates showed a marked increase in Malondialdehyde (MDA) (69.3 ± 4.1 nmol/g) along with a decrease in glutathione (59 ± 5.8 nmol/mg) content and the activity superoxide dismutase (SOD) (0.5 ± 0.05 U/mg protein), glutathione peroxidase (GPx) (16.7 ± 1.1 μmol/mg protein), and catalase (CAT) (73.8 ± 3.9 U/g protein) compared to the levels in control group. Also, the gene expression data for the enzymes SOD, GPx, and CAT dropped dramatically in kidney tissue following Cr (VI) injection. Additionally, Bowman's capsule and glomerulus showed degenerative alterations in the kidney's histopathology and immunohistochemistry. ASE treatment when administered along with Cr (VI) enhanced the activity and gene expression of antioxidant enzymes and improved histopathological conditions. The findings of this study unequivocally show that avocado seed extract, which is rich in phenolic derivatives, is a potent nephroprotective agent that inhibits nephrotoxicity induced by Cr (VI) in rabbits.

Comparative analysis of antioxidant and fatty acid composition in avocado (Persea americana Mill.) fruits: Exploring regional and commercial varieties

On Madeira Island, Portugal, the avocado crop benefits from a Mediterranean climate, exhibiting exceptional phytochemical and biochemical properties. Aiming to evaluate the antioxidant quality and fatty acid composition with a commercial avocado, flours were obtained from five varieties (four regional and one commercial Hass) across different tissues (pulp and by-products) and cycles (years and on-tree maturation stages). Results showed that a regional variety with thin purple skin had the highest antioxidant qualities and lipid content, surpassing the other regional and commercial Hass varieties. Oleic acid prevailed in all samples, with regional avocados containing arachidonic acid which is an uncommon occurrence among higher plants. Variations in fatty acid content were influenced by the timing of harvest. These outcomes highlight the promising potential of avocados from Madeira Island.

Effects of Delaying the Storage of 'Hass' Avocados under a Controlled Atmosphere on Skin Color, Bioactive Compounds and Antioxidant Capacity

During ripening, 'Hass' avocado skin changes from green to purple/black. Low-temperature storage with a controlled atmosphere (CA) is the most widely used method for avocado storage; however, few studies have simulated this technology and considered the days of regular air (RA) storage prior to CA storage. Herein, the effect of delaying the storage of 'Hass' avocado (>30% dry matter) in a CA was examined. Long-term storage conditions (5 °C for 50 days) corresponded to (i) regular air storage (RA), (ii) CA (4 kPa O2 and 6 kPa CO2) and (iii) 10 days in RA + 40 days in a CA and (iv) 20 days in RA + 30 days in a CA. Evaluations were performed during storage and at the ready-to-eat (RTE) stage. Skin color remained unchanged during storage, but at the RTE stage, more color development was observed for fruits stored under CA conditions, as these fruits were purple/black (>50%). At the RTE stage, the anthocyanin content increased, and compared to fruit under RA, fruit under a CA contained a five-fold greater content. A 20-day delay between harvest and CA storage increased the fruit softening rate and skin color development after cold storage, reducing the effectiveness of CA as a postharvest technology for extending storage life.

Unravelling the Influence of Chlorogenic Acid on the Antioxidant Phytochemistry of Avocado (Persea americana Mill.) Fruit Peel

Oxidative stress is pivotal in the pathology of many diseases. This study investigated the antioxidant phytochemistry of avocado (Persea americana Mill.) peel. Different solvent extracts (dichloromethane, ethyl acetate, methanol, and water) of avocado peel were subjected to total phenol and flavonoid quantification, as well as in vitro radical scavenging and ferric reducing evaluation. The methanol extract was subjected to gradient column chromatographic fractionation. Fraction 8 (eluted with hexane:chloroform:methanol volume ratio of 3:6.5:0.5, respectively) was subjected to LC-MS analysis. It was assessed for cellular inhibition of lipid peroxidation and lipopolysaccharide (LPS)-induced ROS and NO production. The DPPH radical scavenging mechanism of chlorogenic acid was investigated using Density Functional Theory (DFT). The methanol extract and fraction 8 had the highest phenol content and radical scavenging activity. Chlorogenic acid (103.5 mg/mL) and 1-O-caffeoylquinic acid (102.3 mg/mL) were the most abundant phenolics in the fraction. Fraction 8 and chlorogenic acid dose-dependently inhibited in vitro (IC50 = 5.73 and 6.17 µg/mL) and cellular (IC50 = 15.9 and 9.34 µg/mL) FeSO4-induced lipid peroxidation, as well as LPS-induced ROS (IC50 = 39.6 and 28.2 µg/mL) and NO (IC50 = 63.5 and 107 µg/mL) production, while modulating antioxidant enzyme activity. The fraction and chlorogenic acid were not cytotoxic. DFT analysis suggest that an electron transfer, followed by proton transfer at carbons 3'OH and 4'OH positions may be the radical scavenging mechanism of chlorogenic acid. Considering this study is bioassay-guided, it is logical to conclude that chlorogenic acid strongly influences the antioxidant capacity of avocado fruit peel.

Microwave-assisted autohydrolysis of avocado seed for the recovery of antioxidant phenolics and glucose

This study describes the valorization of avocado seed (AS) within a green biorefinery concept using microwave-assisted autohydrolysis. After the treatment at temperatures of 150-230 °C for 5 min, the resulting solid and liquor were characterized. The temperature of 220 °C led to the simultaneous optimal values of antioxidant phenolics/flavonoids (42.15 mg GAE/g AS, 31, 89 RE/g AS, respectively) and glucose + glucooligosaccharides (38.82 g/L) in the liquor. Extraction with ethyl acetate allowed the recovery of the bioactive compounds while maintaining the polysaccharides in the liquor. The extract was rich in vanillin (99.02 mg/g AS) and contained several phenolic acids and flavonoids. The solid phase and the phenolic-free liquor were subjected to enzymatic hydrolysis to produce glucose, reaching values of 9.93 and 105 g glucose/L, respectively. This work demonstrates that microwave-assisted autohydrolysis is a promising technology to obtain fermentable sugars and antioxidant phenolic compounds from avocado seeds following a biorefinery scheme.

Nutritional Composition of Hass Avocado Pulp

Avocados (Persea americana) are a unique fruit that can provide health benefits when included in a healthy diet. As health care moves towards precision health and targeted therapies or preventative medicine, it is critical to understand foods and their dietary components. The nutritional composition and plant physiology of the Hass avocado is strikingly different from other fruits. This paper reviews the nutrient and bioactive composition of the edible portion of the Hass avocado (pulp) reported in the literature and from commercial lab analyses of the current market supply of fresh Hass avocados. These results provide comprehensive data on what nutrients and bioactives are in avocado and the quantity of these nutrients. We discuss the reasons for nutrient composition variations and review some potential health benefits of bioactive compounds found in Hass avocados.

Mineral Content and Phytochemical Composition of Avocado var. Hass Grown Using Sustainable Agriculture Practices in Ecuador

Avocado demand has increased in recent years due to the nutraceutical properties that this fruit has and its positive impacts on human health; however, avocado production also requires sustainable alternatives to improve its cultivation. The objective of this study was to carry out characterization of the mineral content and phytochemical compounds in avocado fruit of the Hass variety grown using sustainable agricultural practices in Ecuador. Our results show an increase in fruit quality traits, such as firmness, and in the content of soluble solids, protein, fiber, fat, carotenoids, Ca, Mg, Zn and stearic acid in the pulp of the avocado Hass variety, as well as an initial trend of yield increase with the application of sustainable practices. Moreover, antioxidant activity was associated with polyphenol content. There were positive correlations of Mg with K and Ca, and of flavonoids with linolelaidic, linoleic and linolenic acids. Overall, our results indicate that avocado can be used as a functional and nutritional food due to its phytochemical composition and the mineral content of its pulp, which contributes to the promotion of its consumption and encourages healthy eating. In addition, the use of sustainable practices, such as fertigation and the application of microorganisms, is also promoted for growing avocado.

Possible Side Effects of Polyphenols and Their Interactions with Medicines

Polyphenols are an important component of plant-derived food with a wide spectrum of beneficial effects on human health. For many years, they have aroused great interest, especially due to their antioxidant properties, which are used in the prevention and treatment of many diseases. Unfortunately, as with any chemical substance, depending on the conditions, dose, and interactions with the environment, it is possible for polyphenols to also exert harmful effects. This review presents a comprehensive current state of the knowledge on the negative impact of polyphenols on human health, describing the possible side effects of polyphenol intake, especially in the form of supplements. The review begins with a brief overview of the physiological role of polyphenols and their potential use in disease prevention, followed by the harmful effects of polyphenols which are exerted in particular situations. The individual chapters discuss the consequences of polyphenols’ ability to block iron uptake, which in some subpopulations can be harmful, as well as the possible inhibition of digestive enzymes, inhibition of intestinal microbiota, interactions of polyphenolic compounds with drugs, and impact on hormonal balance. Finally, the prooxidative activity of polyphenols as well as their mutagenic, carcinogenic, and genotoxic effects are presented. According to the authors, there is a need to raise public awareness about the possible side effects of polyphenols supplementation, especially in the case of vulnerable subpopulations.

Enzymatic, Antioxidant, and Antimicrobial Activities of Bioactive Compounds from Avocado (Persea americana L.) Seeds

The aim of this research was to identify and quantify biologically active compounds from avocado (Persea americana L.) seeds (AS) utilizing different techniques with the use of ultrasound (US), ethanol (EtOH), and supercritical carbon dioxide (scCO₂) for possible applications in (bio)medicine, pharmaceutical, cosmetic, or other relevant industries. Initially, a study of the process efficiency (η) was carried out, which revealed yields in the range of 2.96-12.11 wt%. The sample obtained using scCO₂ was found to be the richest in total phenols (TPC) and total proteins (PC), while the sample obtained with the use of EtOH resulted in the highest content of proanthocyanidins (PAC). Phytochemical screening of AS samples, quantified by the HPLC method, indicated the presence of 14 specific phenolic compounds. In addition, the activity of the selected enzymes (cellulase, lipase, peroxidase, polyphenol oxidase, protease, transglutaminase, and superoxide dismutase) was quantified for the first time in the samples from AS. Using DPPH radical scavenging activity, the highest antioxidant potential (67.49%) was detected in the sample obtained with EtOH. The antimicrobial activity was studied using disc diffusion method against 15 microorganisms. Additionally, for the first time, the antimicrobial effectiveness of AS extract was quantified by determination of microbial growth-inhibition rates (MGIRs) at different concentrations of AS extract against three strains of Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas fluorescens) bacteria, three strains of Gram-positive (Bacillus cereus, Staphylococcus aureus, and Streptococcus pyogenes) bacteria, and fungi (Candida albicans). MGIRs and minimal inhibitory concentration (MIC₉₀) values were determined after 8 and 24 h of incubation, thus enabling the screening of antimicrobial efficacy for possible further applications of AS extracts as antimicrobial agents in (bio)medicine, pharmaceutical, cosmetic, or other industries. For example, the lowest MIC₉₀ value was determined for B. cereus after 8 h of incubation in the case of UE and SFE extracts (70 μg/mL), indicating an outstanding result and the potential of AS extracts, as the MIC values for B. cereus have not been investigated so far.