Synthesis of lignin based composites of TiO2 for potential application as radical scavengers in sunscreen formulation

Abstract

Titanium dioxide (TiO 2 ) is added in sunscreens due to its ability to absorb ultraviolet (UV) light. However, upon irradiation of UV light, reactive oxygen species particularly hydroxyl radical which can damage human skin will be generated. In this study, lignin/TiO 2 composites were employed to quench the hydroxyl radicals generated by the TiO 2 . The lignin was extracted from oil palm empty fruit bunch (OPEFB) via kraft and soda pulping processes. The kraft lignin composite was labelled as KL/TiO 2 whereas the soda lignin composite was labelled as SL/TiO 2 . The lignins and the composites were characterized by FTIR, UV spectroscopy, 13 C NMR, SEM, EDX, and XRD. The relative hydroxyl radical production of composites and TiO 2 were compared through photo-oxidation of coumarin to 7-hydroxycoumarin as a test medium. The effect of types and amounts of lignin used were studied. The KL/TiO 2 composite showed the least radical production due to higher phenolic hydroxyl content of kraft lignin. The activity of the hydroxyl radicals will be quenched when it abstract hydrogen atoms from the phenolic hydroxyl groups.

Chemical Fingerprint of Free Polyphenols and Antioxidant Activity in Dietary Fruits and Vegetables Using a Non-Targeted Approach Based on QuEChERS Ultrasound-Assisted Extraction Combined with UHPLC-PDA

“…Table 4 shows the polyphenols identified in our vegetable samples and their respective biological properties. Antidiabetic, Antiinflammatory, Antifungal, Antimicrobial [83][84][85] Antioxidant, Antibacterial, Anti-adipogenic, Anti-inflammatory [74][75][76]…”

Preparation and characterization of lignin-TiO2 UV-shielding composite material by induced synthesis with nanofibrillated cellulose

“…21-1272 due to the low crystallinity of the NFC (Zhang et al 2019). Since lignin is amorphous in nature and lacks ordered structure, the XRD diffractograms of both composites did not show any diffraction peak and that can be referred to lignin, and no other crystalline by-products are formed even after the formation of lignin-TiO2@NFC composite (Ibrahim et al 2019). The results showed that the TiO2@NFC and lignin-TiO2@NFC had increased crystalline structures, which may have been due to the fact that NFC is more malleable and spatial than TiO2 because of its silklike and broom-like structure; in addition, the hydrogen bonds in NFC are stronger, and chemical bonds are more frequent, which results in a better induction effect (Chu et al 2019).…”

“…The study of UVshielding of lignin showed that lignin exhibited antioxidant properties and acted as a free radical scavenger due to the presence of the phenolic hydroxyl groups; the phenolic hydroxyl groups also act as a proton donor and can stabilize the resulting radicals via substituents and delocalization (Sun et al 2014). Ibrahim et al (2019) employed lignin to scavenge the hydroxyl radicals generated from the photocatalytic activity of TiO2 by forming a lignin/TiO2 composite. The results showed that lignin can reduce phototoxicity and scavenge the hydroxyl radicals.…”

Sustainable Esterification of a Soda Lignin with Phloretic Acid

“…FTIR and elemental analysis provided complementary insights on the structural features of the esterified lignin. For the technical lignin, the weak absorption band at ν = 1705 cm −1 corresponds to the conjugated carboxylic acid stretching of the ferulate and the p -coumarate derivatives ( Figure S3 ) [ 61 , 62 ]. Although most of the absorption bands of P2400-PA overlapped with the pattern of P2400, a clear shift was observed in the carboxyl area corresponding to the ester stretching (ν = 1728 cm −1 ), confirming the success of the esterification.…”