Effets des extraits méthanoliques de six espèces du cactus (Opuntia spp.) sur le brunissement des tissus et les bactéries endophytes du palmier dattier (Phoenix dactylifera L.)

Organogenesis is the in vitro regeneration technique used in Morocco for rapid and large-scale propagation of date palm. Unfortunately, this technique is hampered by tissue browning, a physiological disorder that decreases the proliferation capacity of shoot buds and affects the quality of the multiplied plants, and by endophytic bacteria, which are introduced in vitro even if explants are well disinfected. In order to solve these problems, the effects of different concentrations of the methanolic extracts from six Opuntia species were evaluated during shoot bud multiplication of date palm cv. Mejhoul. Organogenic cultures of date palm cv. Mejhoul were cultured for 4 months on semi-solid and half-strength Murashige and Skoog (MS/2) medium, supplemented with plant growth regulators (PGRs) and different concentrations (1, 5 or 10 ml/l) of the methanolic extracts from cladodes of Opuntia megacantha, O. ficus indica, O. robusta, O. aequatorialis, O. leucotricha and O. inermis. Our results showed that, regardless of the cactus pear species used, the concentration of 10 ml/l of the methanolic extract is not suitable for shoot bud multiplication since it results in considerable phytotoxicity. The optimal concentration for shoot bud multiplication was 1 ml/l of the extracts of O. ficus indica, which showed the highest number of shoot buds per explant (14.2), 5% tissue browning and the elimination of endophytic bacteria. The use of the methanolic extracts from cactus pear petals also resulted in bacterium elimination. However, it did not improve the multiplication rate. After the multiplication phase, shoot buds were transferred to the elongation-rooting medium then to glasshouse where a high survival rate of 80% was observed.L'organogenèse est la technique de micropropagation utilisée au Maroc pour la multiplication rapide et massive du palmier dattier. Malheureusement, cette technique est entravée par le brunissement des tissus, un désordre physiologique qui limite la prolifération des bourgeons adventifs et affecte la qualité des plantules multipliées ; et la contamination par les bactéries endophytes qui apparaissent même si les explants sont bien désinfectés. Afin de résoudre ces problèmes, nous avons évalué l’effet des extraits méthanoliques de six espèces d’Opuntia sur la multiplication des bourgeons adventifs du palmier cv. Mejhoul. Ainsi, des souches bourgeonnantes du palmier dattier cv. Mejhoul ont été cultivées pendant 4 mois sur le milieu semi-solide de Murashige et Skoog, dilué de moitié (MS/2), additionnés de régulateurs de croissance et de différentes concentrations (1 ; 5 ou 10 ml/l) d'extraits méthanoliques de cladodes d’Opuntia megacantha, O. ficus indica, O. robusta, O. aequatorialis, O. leucotricha and O. inermis. Nos résultats ont montré que, quel que soit le matériel végétal utilisé, la concentration de 10 ml/l de l'extrait méthanolique entraîne une phytotoxicité accentuée. Par ailleurs, le traitement optimal pour la multiplication des bourgeons est 1 ml/l d'extraits de cladode d’O. ficus indica. Ce traitement a montré le taux de multiplication le plus élevé (14.2 bourgeons par explant), le taux de brunissement le plus faible (5%) et la disparition totale de la bactérie. D’un autre côté, l’utilisation des extraits méthanoliques des pétales a également éliminé la bactérie. Toutefois, ces extraits n’ont pas amélioré le taux de multiplication des bourgeons. Les bourgeons ont été ensuite transférés sur le milieu d’élongation-enracinement puis sous serre où un taux de survie de 80% a été observé

Guava: phytochemical composition of a potential source of antioxidants for cosmetic and/or dermatological applications

ABSTRACT Guava (Psidium guajava L.) is a native fruit of the American tropics with commercial applications for its taste, flavor and aroma. Numerous pharmacological uses have been described for it, such as the antiseptic effect of its leaves, the use of the fresh fruit and tea from its leaves for the treatment of diarrhea, dysentery, diabetes mellitus, and others. However, considering its rich composition, the guava also is a potential source of antioxidants to be used in the development of new formulations for cosmetic and/or dermatological applications, the main focus of this research. Herein, we describe the study of the phytochemical composition and the antioxidant activity of a guava extract prepared with non-toxic solvents aiming its use at biological applications. High performance liquid chromatography and mass spectrometry were employed to identify the major components, while thermoanalytical measurements and hot stage microscopy were used to assess the chemical stability of guava fruit extract. The antioxidant activity was also evaluated assessing the SOD-like activity and ABTS free radical scavenger. The results show that the extract is a rich source of phenolic compounds, such as quercetin, kaempferol, schottenol, among many others. All of the components found in guava extract exhibit biological effects according to the literature data, mainly antioxidant properties