Phenolic composition, antioxidant and antiacetylcholinesterase activities of Opuntia ficus-indica peel and flower teas after in vitro gastrointestinal digestion

BACKGROUND

The flowers and peels of cactus Opuntia ficus-indica (OFI) are by-products generally discarded. Their beneficial properties have been linked to the chemical composition without taking into account its transformations during digestion. This study evaluated and compared the phenolic composition, antioxidant and antiacetylcholinesterase activities of OFI peel and flower teas before and after in vitro gastrointestinal digestion.

RESULTS

Results showed that OFI peel tea was a source of natural phenolic compounds and carotenoids, while OFI flower tea was a source of flavonoids. Both OFI peel and flower teas exhibited high antioxidant activities (AAs) measured by several tests [1,1-diphenyl-2-picrylhydrazyl radical (DPPH^• ), reducing power (RP), hydrogen peroxide scavenging activity (HPSA)]. Flower teas presented a higher antiacetylcholinesterase inhibition percentage than peel teas. Significant decreases of acetylcholinesterase and AAs were obtained under in vitro gastrointestinal digestion. Fourteen phenolic compounds typical of phenolic acids and flavonoids were identified in both teas. These compounds seemed to be more affected by pancreatic than by the gastric conditions.

CONCLUSION

OFI peel tea has been found as a source of natural phenolic compounds and carotenoids, while OFI dry flower tea as a source of flavonoids. The OFI flower tea phytochemicals were more stable than peel tea during the digestive process. These findings suggest that peels and flowers of OFI should be considered as sources of healthy ingredients. © 2022 Society of Chemical Industry.

Chemical parameters and antioxidant activity of turning color natural-style table olives of the Sigoise cultivar

A chemical characterization of turning color table olives of the Sigoise variety was made through their processing as natural-style. Polyphenols, sugars, tocopherols, fatty acids, and antioxidant activity in the olives were monitored throughout the elaboration process. Oleuropein, salidroside, hydroxytyrosol 4-glucoside, rutin, ligustroside and verbascoside showed a decrease of 16.90-83.34%, while hydroxytyrosol increased during the first months of brining. Glucose was consumed by 90% due to the metabolism of the fermentative microbiota. The tocopherol content remained stable during the process and only the α-tocopherol decreased. The fatty acids were not affected. The loss in antioxidant compounds resulted in a decrease in the percentage of DPPH radical inhibition from 75.91% in the raw fruit to 44.20% after 150 days of brining. Therefore, the turning color natural table olives of the Sigoise variety are a good source of bioactive compounds.

Genetic flow among olive populations within the Mediterranean basin

Background

The olive tree is a typical crop of the Mediterranean basin where it shows a wide diversity, accounting for more than 2,600 cultivars. The ability to discriminate olive cultivars and determine their genetic variability is pivotal for an optimal exploitation of olive genetic resources.

Methods

We investigated the genetic diversity within 128 olive accessions belonging to four countries in the Mediterranean Basin (Italy, Algeria, Syria, and Malta), with the purpose of better understanding the origin and spread of the olive genotypes across Mediterranean Basin countries. Eleven highly polymorphic simple sequence repeat (SSR) markers were used and proved to be very informative, producing a total of 179 alleles.

Results

Cluster analysis distinguished three main groups according to their geographical origin, with the current sample of Maltese accessions included in the Italian group. Phylogenetic analysis further differentiated Italian and Maltese olive accessions, clarifying the intermediate position of Maltese accessions along the x/y-axes of principal coordinate analysis (PCoA). Model-based and neighbor clustering, PCoA, and migration analysis suggested the existence of two different gene pools (Algerian and Syrian) and that the genetic exchange occurred between the Syrian, Italian and Maltese populations.

Discussion

The close relationship between Syrian and Italian and Maltese olives was consistent with the historical domestication and migration of olive tree from the North Levant to eastern Mediterranean basin. This study lays the foundations for a better understanding of olive genetic diversity in the Mediterranean basin and represents a step toward an optimal conservation and exploitation of olive genetic resources.

Phenolic profiles of eight olive cultivars from Algeria: effect of Bactrocera oleae attack

Olive fly (Bactrocera oleae R.) is the most harmful pest of olive trees (O. europaea) affecting their fruit development and oil production. Olive fruits have characteristic phenolic compounds, important for plant defense against pathogens and insects, and with many biological activities, they contribute to the high value of this crop. In this study, olives from 8 cultivars (Abani, Aellah, Blanquette de Guelma, Chemlal, Ferkani, Limli, Rougette de Mitidja and Souidi) with different degrees of fly infestation (0%, not attacked; 100%, all attacked; and real attack %) and different maturation indices were sampled and analysed. Qualitative and quantitative analyses of phenolic profiles were performed by colorimetric methodologies and RP-HPLC-DAD. Verbascoside, tyrosol and hydroxytyrosol were the compounds that were most adversely affected by B. oleae infestation. Principal component analysis and hierarchical cluster analysis highlighted different groups, showing different behaviours of olive cultivars to the attack. The results show that phenolic compounds displayed sharp qualitative and quantitative differences among the cultivars. The fly attack was significantly correlated with the weight of the fruits, but not with the phenolic compounds.

Effect of Bactrocera oleae on phenolic compounds and antioxidant and antibacterial activities of two Algerian olive cultivars

Bactrocera oleae, an olive fruit fly, is a major olive pest in Algeria.

The effect of the olive fruit fly (Bactrocera oleae) on quality parameters, and antioxidant and antibacterial activities of olive oil

This study shows the importance of controlling the fly attack because it causes a decrease in the beneficial health effects of olive oils.