β-Carotene

The development and characterization of biodegradable blend films based on chitosan and poly (vinyl alcohol) for possible use in a variety of biological activities are reported. Fourier transform infrared spectroscopy (FTIR) spectra of chitosan-poly (vinyl alcohol) (Ch/PVA) films showed characteristics peaks shifting to a lower frequency range due to hydrogen bonding between -OH of PVA and -NH2 of chitosan. The chitosan and PVA polymers presented good compatibility. The morphology study of chitosan and composite films showed a compact and homogenous structure. The tensile strength and elongation at break increased with PVA content. In fact, the highest tensile strength and elongation at break (53.58 MPa and 454 %) occurs with pure PVA film. The results showed that PVA incorporation in the blends contributes to increase the intermolecular interactions, thus improving the mechanical properties. In addition, the prepared films demonstrated high antioxidant activities monitored by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging, reducing power, and β-carotene bleaching activity.

Provitamin A carotenoids are oxidatively cleaved by β-carotene 15-15'-dioxygenase (BCO1) at the central 15-15' double bond to form retinal (vitamin A aldehyde). Another carotenoid oxygenase, β-carotene 9'-10'-oxygenase (BCO2) catalyzes the oxidative cleavage of carotenoids at the 9'-10' bond to yield an ionone and an apo-10'-carotenoid. Previously published substrate specificity studies of BCO2 have been conducted using crude lysates from bacteria or insect cells expressing recombinant BCO2. Our attempts to obtain active recombinant human BCO2 expressed in Escherichia coli were unsuccessful. We have expressed recombinant chicken BCO2 in the strain E.coli BL21-Gold (DE3) and purified the enzyme by cobalt ion affinity chromatography. Like BCO1, purified recombinant chicken BCO2 reacts with the provitamin A carotenoids β-carotene, α-carotene, and β-cryptoxanthin. Its catalytic activity with β-carotene as substrate is at least 10-fold lower than that of BCO1.

Citrus x limon cv Femminello comune (Rutaceae) from Rocca Imperiale (Italy), one of the six PGI (Protected Geographical Indication) Italian lemon crops, has been recently received renewed interest. In this work, fresh and dried peels and leaves were extracted by using hydrodistillation, supercritical fluid extraction (SFE) and Soxhlet apparatus. Chemical profile was assessed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Except for leaves extracts obtained by Soxhlet apparatus, the monoterpene hydrocarbons fraction dominated. Limonene, γ-terpinene and β-pinene were the main identified compounds. The antioxidant activity was investigated by using different in vitro assays namely DPPH, ABTS, FRAP and β-carotene bleaching test. In DPPH test the essential oil obtained by hydrodistillation of fresh peel exhibited the highest activity (IC50 of 1.17 mg/ml). Leaves extracted by SFE showed a good activity in both DPPH and β-carotene bleaching test with IC50 values of 2.

BACKGROUND: Carotenoids are important pigments and precursors for central signaling molecules associated in fruit development and ripening. Carotenoid metabolism has been studied especially in the climacteric tomato fruit but the content of carotenoids and the regulation of their metabolism have been shown to be highly variable between fruit species. Non-climacteric berries of the genus Vaccinium are among the best natural sources of health-beneficial flavonoids but not studied previously for carotenoid biosynthesis.