Antioxidant activity of lettuce extract (Lactuca sativa) and synergism with added phenolic antioxidants

Characterization of Orange Peel Extract and Its Potential Protective Effect against Aluminum Chloride-Induced Alzheimer's Disease

Alzheimer's disease (AD) is a devastating neurodegenerative disorder without a cure. Hence, developing an effective treatment or protective agent is crucial for public health. The present study aims to characterize orange peel extract (OPE) through in vitro and in silico studies. Furthermore, it examines the protective effect of OPE against experimentally-induced Alzheimer's disease in rats. The total phenolic and flavonoid content of OPE was 255.86 ± 1.77 and 52.06 ± 1.74 (mg/100 g), respectively. Gallic acid, the common polyphenol in OPE detected by HPLC was 3388.60 μg/100 g. OPE antioxidant IC₅₀ was 67.90 ± 1.05, 60.48 ± 0.91, and 63.70 ± 0.30 by DPPH, ABTS and Hydroxyl radical scavenging activity methods, respectively. In vitro anti-acetylcholinesterase (AChE) IC₅₀ was 0.87 ± 0.025 mg/mL for OPE and 2.45 ± 0.001 mg/mL for gallic acid. Molecular docking analysis for human AChE (4EY7) with donepezil, gallic acid, and acetylcholine showed binding energy ΔG values of -9.47, -3.72, and -5.69 Kcal/mol, respectively. Aluminum chloride injection (70 mg/Kg/day for 6 weeks) induced Alzheimer's-like disease in male rats. OPE (100 and 200 mg/kg/d) and gallic acid (50 mg/kg/d) were administered orally to experimental animals for 6 weeks in addition to aluminum chloride injection (as protective). OPE was found to protect against aluminum chloride-induced neuronal damage by decreasing both gene expression and activity of acetylcholinesterase (AChE) and a decrease in amyloid beta (Aβ42) protein level, thiobarbituric acid-reactive substances (TBARS), and nitric oxide (NO), and increased reduced glutathione (GSH) level and activity of the antioxidant enzymes in the brain tissues. Additionally, gene expressions for amyloid precursor protein (APP) and beta secretase enzyme (BACE1) were downregulated, whereas those for presinilin-2 (PSEN2) and beta cell lymphoma-2 (BCL2) were upregulated. Furthermore, the reverse of mitochondrial alternation and restored brain ultrastructure might underlie neuronal dysfunction in AD. In conclusion, our exploration of the neuroprotective effect of OPE in vivo reveals that OPE may be helpful in ameliorating brain oxidative stress, hence protecting from Alzheimer's disease progression.

Phytochemicals, Nutrition, Metabolism, Bioavailability, and Health Benefits in Lettuce-A Comprehensive Review

Lettuce is one of the most famous leafy vegetables worldwide with lots of applications from food to other specific uses. There are different types in the lettuce group for consumers to choose from. Additionally, lettuce is an excellent source of bioactive compounds such as polyphenols, carotenoids, and chlorophyll with related health benefits. At the same time, nutrient composition and antioxidant compounds are different between lettuce varieties, especially for green and red lettuce types. The benefit of lettuce consumption depends on its composition, particularly antioxidants, which can function as nutrients. The health benefits rely on their biochemical effect when reaching the bloodstream. Some components can be released from the food matrix and altered in the digestive system. Indeed, the bioaccessibility of lettuce is measuring the quantity of these compounds released from the food matrix during digestion, which is important for health-promoting features. Extraction of bioactive compounds is one of the new trends observed in lettuce and is necessarily used for several application fields. Therefore, this review aims to demonstrate the nutritional value of lettuce and its pharmacological properties. Due to their bioaccessibility and bioavailability, the consumer will be able to comprehensively understand choosing a healthier lettuce diet. The common utilization pattern of lettuce extracted nutrients will also be summarized for further direction.

The synergistic and antagonistic antioxidant interactions of dietary phytochemical combinations

The frequent intake of whole foods and dietary food variety is recommended due to their health benefits, such as prevention of multiple chronic diseases, including cancer, Alzheimer's disease, cardiovascular diseases, and type 2 diabetes mellitus. Often, consuming whole fruits or vegetables showed the enhanced effects than consuming the individual dietary supplement from natural products, which is widely explained by the interactive effects of co-existing phytochemicals in whole foods. Although research relevant to interactive effects among the bioactive compounds mounted up, the mechanism of interaction is still not clear. Especially, biological influence factors such as bioavailability are often neglected. The present review summarizes the progress on the synergistic and antagonistic effects of dietary phytochemicals, the evaluating models for antioxidant interactions, and the possible interaction mechanisms both in vitro and in vivo, and with an emphasis on biological-related molecular mechanisms of phytochemicals. The research on the interaction mechanism is of value for guiding how to take advantage of synergistic effects and avoid antagonistic effects in daily diets or phytochemical-based treatments for preventing chronic diseases.

Physiological relevance of food antioxidants

Dietary antioxidants are associated with prevention of oxidative stress related chronic diseases including certain types of cancer, cardiovascular diseases, diabetes, and neurodegenerative diseases. In recent years, there has been a growing interest in extending the knowledge on their physiological effects in human body. There are numbers of epidemiological, clinical, meta-analysis, and in vitro studies to explain formation mechanisms of each chronic diseases as well as the potential effects of dietary antioxidants on these diseases and gut health. Comprehensive studies for food antioxidants' journey from dietary intake to target tissues/organs deserve a serious consideration to have a clear understanding on the physiological effects of dietary antioxidants. Therefore, absorption and metabolism of dietary antioxidants, and the factors affecting their absorption, such as solubility of antioxidants, food matrix, and interaction between antioxidants have been evaluated in several research articles. This chapter provides an overview about potential health effects of dietary antioxidants considering with their absorption and metabolism in human body.

Dissipation Profiles of Tristyrylphenol Ethoxylate Homologs in Lettuce under Greenhouse and Field Conditions

Tristyrylphenol ethoxylates (TSPEOs) have been increasingly used in pesticide formulations as inert ingredients in China, but little information exists on the dissipation behavior of TSPEOs in foodstuffs. In this work, a rapid method for measuring TSPEO homologs in lettuce using QuEChERS and HPLC-MS/MS was established. This method was used to study the dissipation and distribution profiles of TSPEOs in lettuce. TSPEO homologs degraded rapidly under greenhouse and field conditions, with half-lives of 2.18-5.39 and 1.82-5.52 days, respectively. TSPEOn (n = 6-9) were relatively persistent in the field. The distribution profiles showed an obvious difference between the two conditions. TSPEOn (n = 14-18) degraded to shorter-chain TSPEOs with time, and a two-peak (TSP16EO and TSP10EO) homolog distribution profile occurred between 7 and 14 days of treatment under greenhouse conditions. This work improves the understanding of the dissipation behavior of TSPEO homologs in lettuce.

Earthworm Grazed-Trichoderma harzianum Biofortified Spent Mushroom Substrates Modulate Accumulation of Natural Antioxidants and Bio-Fortification of Mineral Nutrients in Tomato

The present investigation was aimed at evaluating the impact of earthworm grazed and Trichoderma harzianum biofortified spent mushroom substrate (SMS) on natural antioxidant and nutritional properties of tomato. Results of the investigation reveal that earthworm grazing and T. harzianum bio-fortification led to significant improvement in the physico-chemical properties of fresh SMS and its application increased the accumulation of natural antioxidants and mineral content in tomato as compared to either T. harzianum biofortified SMS or fresh SMS. In particular, the earthworm grazed, T. harzianum biofortified SMS (EGTHB-SMS) was found to inhibit lipid peroxidation and protein oxidation with significant increase in total polyphenol and flavonoid content in tomato. Further, it increased Fe2+/Fe3+ chelating activity, superoxide anion radical scavenging activity compared to other treatments. The results thus suggest an augmented elicitation of natural antioxidant properties in tomato treated with EGTHB-SMS, resulting in a higher radical scavenging activity, that is highly desirable for human health. In addition, the use of SMS to enhance the nutritional value of tomato fruits becomes an environment friendly approach in sustainable crop production.

Structure, gelation, and antioxidant properties of curcumin-doped casein micelle powder produced by spray-drying

The encapsulation of curcumin in micellar caseins (MCs) and the production of powder were performed by spray-drying.

Evaluation of Radical Scavenging Activity of Sempervivum tectorum and Corylus avellana Extracts with Different Phenolic Composition

Sempervivum tectorum L. and Corylus avellana L. are traditional herbal remedies exhibiting antioxidant activity and representing diverse phenolic composition. The aim of this study was to reveal the contribution of certain compounds to total radical scavenging activity by studying S. tectorum and C. avellana extracts prepared with solvents of different selectivity for diverse classes of phenolics. Antioxidant activity of S. tectorum and C. avellana samples was determined in the ABTS and DPPH radical scavenging assays, and phenolic composition was evaluated by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Correlations between antioxidant activity and phenolic content of houseleek extracts have been revealed. Significant differences regarding antioxidant activity have been shown between S. tectorum 80% (v/v) methanol extract and its fractions. Additionally, synergism among the constituents present together in the whole extract was assumed. Significantly higher radical scavenging activity of hazel extracts has been attributed to the differences in phenolic composition compared with houseleek extracts.

pH dependent antioxidant activity of lettuce (L. sativa) and synergism with added phenolic antioxidants

Influence of pH on the antioxidant activities of combinations of lettuce extract (LE) with quercetin (QC), green tea extract (GTE) or grape seed extract (GSE) was investigated for both reduction of Fremy's salt in aqueous solution using direct electron spin resonance (ESR) spectroscopy and in L-α-phosphatidylcholine liposome peroxidation assay measured following formation of conjugated dienes. All examined phenolic antioxidants showed increasing radical scavenging effect with increasing pH values by using both methods. QC, GTE and GSE acted synergistically in combination with LE against oxidation of peroxidating liposomes and with QC showing the largest effect. The pH dependent increase of the antioxidant activity of the phenols is due to an increase of their electron-donating ability upon deprotonation and to their stabilization in alkaline solutions leading to polymerization reaction. Such polymerization reactions of polyphenolic antioxidants can form new oxidizable -OH moieties in their polymeric products resulting in a higher radical scavenging activity.

Determination of pesticides in lettuce using solid-liquid extraction with low temperature partitioning

This work describes the optimization and validation of a method employing solid-liquid extraction with low temperature partitioning (SLE/LTP) together with analysis by gas chromatography with electron capture detection (GC/ECD) for the determination of nine pesticides (chlorothalonil, methyl parathion, procymidone, endosulfan, iprodione, λ-cyhalothrin, permethrin, cypermethrin, and deltamethrin) in lettuce. The method was found to be selective, accurate, and precise, with means recovery values in the range of 72.3-103.2%, coefficients of variation ⩽ 12%, and detection limits in the range 0.4-37 μg kg(-1). The matrix components significantly influence the chromatographic response of the analytes (above 10%). The optimized and validated method was applied to determine the residual concentrations of the fungicides iprodione and procymidone that had been applied to field crops of lettuce. The maximum residual concentrations of the pesticides in the lettuce samples were 13.6 ± 0.4 mg kg(-1) (iprodione) and 1.00 ± 0.01 mg kg(-1) (procymidone), on the day after application of the products.

Kaempferol and inflammation: From chemistry to medicine

Inflammation is an important process of human healing response, wherein the tissues respond to injuries induced by many agents including pathogens. It is characterized by pain, redness and heat in the injured tissues. Chronic inflammation seems to be associated with different types of diseases such as arthritis, allergies, atherosclerosis, and even cancer. In recent years natural product based drugs are considered as the novel therapeutic strategy for prevention and treatment of inflammatory diseases. Among the different types of phyto-constituents present in natural products, flavonoids which occur in many vegetable foods and herbal medicines are considered as the most active constituent, which has the potency to ameliorate inflammation under both in vitro and in vivo conditions. Kaempferol is a natural flavonol present in different plant species, which has been described to possess potent anti-inflammatory properties. Despite the voluminous literature on the anti-inflammatory effects of kaempferol, only very limited review articles has been published on this topic. Hence the present review is aimed to provide a critical overview on the anti-inflammatory effects and the mechanisms of action of kaempferol, based on the current scientific literature. In addition, emphasis is also given on the chemistry, natural sources, bioavailability and toxicity of kaempferol.

Mechanism of protective effect of lettuce against glucose/serum deprivation-induced neurotoxicity

OBJECTIVES

The present study investigated the protective effect of ethyl acetate fraction of lettuce (Lactuca sativa) against glucose/serum deprivation (GSD)-induced neurotoxicity, a model which simulates neuronal damage during ischemia.

METHODS

Two neuron-like cells, N2a and PC12, were cultivated for 12 hours in GSD condition in the absence or presence of the lettuce fraction. The cell viability, DNA damage, and proapoptotic or antiapoptotic proteins levels were determined using MTT, comet, and immunoblotting assays, respectively. In addition, the intracellular reactive oxygen species and lipid peroxidation levels were measured by fluorimetric methods.

RESULTS

In both N2a and PC12 cells, GSD condition significantly decreased the cell viability which was accompanied by increased intracellular reactive oxygen species production, lipid peroxidation level, and oxidative DNA damage. All the GSD-induced neurotoxic changes were inhibited by the lettuce fraction. Lettuce also suppressed the elevated Bax and caspase-3 proteins and decreased Bcl-2 induced by GSD in PC12 cells.

DISCUSSION

The present study revealed that lettuce exerts neuroprotective effect through decrease of oxidative stress and inhibition of proapoptotic pathways. Therefore, it has the potential to be used for the management of ischemia-induced neuronal damage.

Synergism between soluble and dietary fiber bound antioxidants

This study investigates the synergism between antioxidants bound to dietary fibers (DF) of grains and soluble antioxidants of highly consumed beverages or their pure antioxidants. The interaction between insoluble fractions of grains containing bound antioxidants and soluble antioxidants was investigated using (i) a liposome-based system by measuring the lag phase before the onset of oxidation and (ii) an ESR-based system by measuring the reduction percentage of Fremy's salt radical. In both procedures, antioxidant capacities of DF-bound and soluble antioxidants were measured as well as their combinations, which were prepared at different ratios. The simple addition effects of DF-bound and soluble antioxidants were compared with measured values. The results revealed a clear synergism for almost all combinations in both liposome- and ESR-based systems. The synergism observed in DF-bound-soluble antioxidant system paints a promising picture considering the role of fiber in human gastrointestinal (GI) tract health.

Antioxidative properties and ability of phenolic compounds of Myrtus communis leaves to counteract in vitro LDL and phospholipid aqueous dispersion oxidation

Antioxidant activities of Myrtus communis leaf phenolic compounds (McPCs) were investigated on 2,2'-9-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS(+) •) and oxygen radical absorbance capacity (ORAC) tests or on oxidation of biological models, human low-density lipoprotein (LDL) and phospholipid aqueous dispersion (L-α-phosphatidylcholine stabilized by bile salts). Two extraction techniques, microwave-assisted (MAE) and conventional (CE), were used to isolate McPCs, producing similar results of phenolic compound content. ABTS(+) • assay showed clearly that myrtle extracts exhibited a stronger scavenging effect than butylated hydroxyanisole and α-tocopherol, with a slight advantage for myrtle CE extract. In ORAC assay, the both McPC extracts were similarly less effective than the pure compounds as caffeic acid and myricitrin (myricetin 3-O-rhamnoside) but stronger than butylated hydroxytoluene. Moreover, myrtle CE and MAE extracts, and myricitrin were able to inhibit similarly the production of conjugated dienes and to prolong the lag phase (Tlag) during Cu(2+)-induced LDL oxidation with a dose-response effect. The cryo-electron microscopy observations on studied phospholipid dispersion stabilized by bile salts (BS) revealed the presence of bilayer vesicles and micelles. In 2,2'-azobis (2-amidinopropane) hydrochloride-induced phospholipid/BS oxidation, myrtle CE and MAE extracts gave similar effects to α-tocopherol and caffeic acid but myricitrin showed a higher protective effect than myrtle extracts. We showed also that no synergic or additive effect between α-tocopherol and myrtle extracts or caffeic acid in α-tocopherol-enriched phospholipid/BS dispersion, but myricitrin showed an additive effect and thus promoted the total antioxidant activity. These data showed that myrtle extract could be used as potential natural antioxidants, food stabilizers, or natural health products.

PRACTICAL APPLICATION

We show that microwave-assisted extraction could be an alternative method for plant phenolic compound recovery allowing important gain in time extraction.We report inhibition of low-density lipoprotein oxidation in vitro initiated by Cu(2+) ions. We report that myrtle extract may be a source of natural antioxidants to counteract phospholipid peroxidation as well as α-tocopherol.

Chemical composition of essential oils and in vitro antioxidant activity of fresh and dry leaves crude extracts of medicinal plant of Lactuca Sativa L. native to Sultanate of Oman

OBJECTIVE

To isolate and analyse the chemical composition in the essential oils and free radical scavenging activity of different crude extracts from the fresh and dry leaves of vegetable plants of Lactuca sativa L. (L. sativa).

METHODS

The essential oils and volatile chemical constituents were isolated from the fresh and dry leaves of L. sativa (lettuce) grown in Sultanate of Oman by hydro distillation method. The antioxidant activity of the crude extracts was carried out by well established free radical scavenging activity (DPPH) method.

RESULTS

About 20 chemical compounds of different concentration representing 83.07% and 79.88% respectively were isolated and identified by gas chromatography-mass spectroscopy in the essential oils isolated from the fresh and dry leaves as α-pinene (5.11% and 4.05%), γ-cymene (2.07% and 1.92%), thymol (11.55% and 10.73%), durenol (52.00% and 49.79%), α-terpinene (1.66% and 1.34%), thymol acetate (0.99% and 0.67%), caryophyllene (2.11% and 1.98%), spathulenol (3.09% and 2.98%), camphene (4.11% and 3.65%), limonene (1.28% and 1.11%) representing these major chemical compounds. However, some other minor chemical constituents were also isolated and identified from the essential oil of lettuce including β-pinene, α-terpinolene, linalool, 4-terpineol, α-terpineol, o-methylthymol, L-alloaromadendrene and viridiflorene.

CONCLUSIONS

The chemical constituents in the essential oils from the locally grown lettuce were identified in the following classes or groups of chemical compounds such as monoterpenes, sesquiterpenes volatile organic compounds and their oxygenated hydrocarbons. Therefore, the essential oils and the crude extracts from Omani vegetable species of lettuce are active candidates which would be used as antioxidant, antifungal or antimicrobial agents in new drugs preparation for therapy of infectious diseases.

Effect of five different stages of ripening on chemical compounds in medlar (Mespilus germanica L.)

The study of changes of nutritional value of fruit during the ripening process can help estimate the optimal date for fruit harvesting to achieve the best quality for direct consumption and further utilization. The aim of this study was to monitor the changes of chemical composition of medlar fruit (Mespilus germanica L.) measured at five various ripening stages including 134, 144, 154, 164 and 174 days after full bloom (DAFB). Fruits were analyzed and ascorbic acid (AA) and total phenolic compound content with respect to the total antioxidant activity were determined. In addition, selected micronutrients and macronutrients were monitored. The results of our experiments demonstrate that ascorbic acid, total phenolic compound content and total antioxidant activity decreased significantly with increasing time of ripeness. The decreasing tendency in potassium, calcium and magnesium contents during the ripening stages was also determined. During the ripening period, the content of all micronutrients as well as phosphorus and sodium was balanced, with no statistically significant differences between the monitored ripening stages, which can be considered as a positive fact with respect to ideal consumption quality of fruit.

Multiresidue determination of carbamate, organochlorine, organophosphorus, and dicarboximide pesticides in lettuce by GC/MS

An extraction method based on matrix solid-phase dispersion was developed to determine pirimicarb, methyl parathion, malathion, procymidone, alpha-endosulfan and beta-endosulfan in lettuce using gas chromatography-mass spectrometry. The best results were obtained using 4.0 g of lettuce, 2.0 g of silica as dispersant sorbent, 0.1 g of activated carbon as clean up sorbent and acetonitrile as eluting solvent. The method was validated using lettuce samples fortified with pesticides at six different concentration levels (0.1 to 2.0 mg/kg). Average recoveries (7 replicates) ranged from 50 to 120%, with relative standard deviations between 0.6 and 8.0%. Detection and quantification limits for lettuce ranged from 0.01 to 0.02 mg/kg and 0.04 to 0.10 mg/kg, respectively.