The Bioactive Compounds in Agricultural Products and Their Roles in Health Promoting Functions

Bioactive compounds from different agricultural food products have attracted great interest from food industries and researchers for their health promoting functions such as antioxidant, antiaging, anti-inflammatory and anticancer performance. In this study, hydrophilic and lipophilic fraction of two economical agricultural products sweet sorghum millet and sweet potato, as well as two herbs, butterfly pea and basil were extracted. The profiles and contents of phenolics, fatty acids, tocopherols, carotenoids and phytosterols in these selected agricultural products were determined by chromatography and mass spectrum methods. Additionally, the anti-lipid-oxidation capability of sweet sorghum millet and basil, and anti-cancer potential of butterfly pea seed or petal and sweet potato were evaluated by emulsion models (cholesterol or cholesterol-linoleic acid emulsion) and cancer cell lines (HEp-2 and PC-12), respectively. In the study of sweet sorghum millet, nine major hydrophilic phytochemicals were quantified at levels of 8.9 μg/g for cinnamic acid to 1570.0 μg/g for apigeninidin, and lipophilic phytochemicals including α- and γ-tocopherol, lutein and β-carotene were quantified at levels of 7.7, 145.7, 4.8, and 18.8 μg/g, respectively. The total phenolic content, scavenging DPPH activity and the ability of inhibiting cholesterol oxidation or stabilizing linoleic acid in hydrophilic extracts of the sweet sorghum millets were significantly higher than its lipophilic extracts. In Thai holy/sweet basil leaves or seeds, eight phenolics rosmarinic, caftaric, caffeic, chicoric, p-hydroxybenzoic, p-coumaric, protocatechuic acid and rutin were identified. The total phenolic content of Thai sweet basil leaves (TSBL) was significantly higher than Thai holy basil leaves (THBL), Thai holy (THBS) and sweet basil seed (TSBS). The order of scavenging DPPH free radical x activity and anti-lipid-oxidation ability from high to low was THBL, TSBL, THBS and TSBS. Butterfly pea seeds contained fifteen major phenolics such as sinapic acid, epicatechin and hydroxycinnamic acid derivative with concentrations above 0.5 mg/g FW, while its petals contained a group of ternatins (A1, B2, B3, C2, D2 and D3), flavone glycosides, delphinidin derivatives and ellagic acid. Both seeds and petals had four different phytosterols and - and - tocopherol. Linoleic acid is the highest level of fatty acid in both seeds and petals, while phytanic acid was only found in the petals. The cellular study demonstrated that hydrophilic butterfly pea seed (HBS) exhibited significantly higher capability than its petal (HBP) in inhibiting the proliferation of HEp-2 cells. However, the capability of lipophilic extracts of both seed and petal were much lower than their corresponding hydrophilic extracts. In the sweet potato study, most of the phenolic compounds, fatty acids, and phytostrols significantly increased, and four more phenolic acids were found after fermentation of sweet potato due to the enzymatic action of Lactobacillus acidophilus LA-K compared with raw sweet potato. In the anticancer potential study, the fermented sweet potato extracts exhibited higher efficiency than raw extracts in inhibiting the cancer cell PC-12 proliferation. Also, purified hydrophilic extracts of raw or fermented extracts had greater anticancer potential than their corresponding lipophilic extracts. However, each type of extracts had little influence on the normal monkey kidney cell (CV-1) growth. Based on the dissertation research, the natural agricultural extracts could be used as health promoting ingredients in functional food or potential therapeutic ingredients for cancer treatment

Q-factor mediated quasi-BIC resonances coupling in asymmetric dimer lattices

Resonance coupling in the regime of bound states in the continuum (BICs) provides an efficient method for engineering nanostructure's optical response with various lineshape while maintaining an ultra-narrow linewidth feature, where the quality factor of resonances plays a crucial role. Independent manipulation of the Q factors of BIC resonances enables full control of interaction behavior as well as both near- and far-field light engineering. In this paper, we harness reflection symmetry (RS) and translational symmetry (TS) protected BIC resonances supported in an asymmetric dimer lattice and investigate Q-factor-mediated resonance coupling behavior under controlled TS and RS perturbations. We focus on in-plane electrical dipole BIC (EDi-BIC) and magnetic dipole BIC (MD-BIC) which are protected by RS, and out-of-plane electrical dipole BIC (EDo-BIC) protected by TS. The coupling between EDi-BIC and EDo-BIC exhibits a resonance crossing behavior where the transmission spectrum at the crossing could be tuned flexibly, showing an electromagnetically induced transparency lineshape or satisfying the lattice Kerker condition with pure phase modulation capability depending on TS and RS perturbed Q factors. While the coupling between MD-BIC and EDo-BIC shows an avoided resonance crossing behavior, where the strongly coupled resonances would lead to the formation of a Friedrich-Wintgen BICs whose spectral position could also be shifted by tuning the Q factors. Our results suggest an intriguing platform to explore BIC resonance interactions with independent Q factor manipulation capability for realizing multi-functional meta-devices

Plant metabolites in response to pathogen and gene mutations

Abstract: In response to environmental stresses, plants induce complex signal transduction cascades that can lead to dramatic changes in profiles of gene expression and metabolites. In some instances, plants respond to pathogen stress by increasing production of defense chemicals such as polyphenols. Normal cellular functions of polyphenols depend on methylation of their hydroxyl groups at specific positions via reactions catalyzed by O-methyltransferases (OMTs), some of which are induced in pathogen stress. OMTs belong to a group of enzymes involved in the methylation of hydroxyl groups from many compounds in both animals and plants. O-methylation catalyzed by OMTs involves the transfer of the methyl group from S-adenosyl-L-methionine (SAM) to the hydroxyl group of an acceptor molecule, with the formation of its methylated derivative and S-adenosyl-L-homocysteine (SAH) as products. In this study, we summarized changes on plant secondary metabolites in response to pathogen stress and gene mutations, particularly to OMT mutants

Changes of the Anthocyanins and Antioxidant properties of Concord Grape (Vitis labrusca) Pomace After Acid Hydrolysis

Grape pomace contains high levels of valuable antioxidants such as anthocyanins and phenolic compounds that help prevent chronic diseases such as cardiovascular problems and cancers. In this study, Concord grape pomace was soaked in acidic solutions at different time intervals and pHs in a water bath at 80 degrees C. Five kinds of anthocyanins were released and identified in the pomace after acid hydrolysis. The releasing rate of anthocyanins and antioxidant activities of the acid hydrolyzed pomace extracts were determined by multitest systems. Different antioxidant assays including total antioxidant capacity (TAC), total phenolic content (TPC) and free radical scavenging activity (RSA) were used to evaluate the antioxidant properties of the acid hydrolyzed pomace extracts. The change in antioxidant capacity of the pomace extracts during hydrolysis was correlated with total phenolic content and free radical scavenging activity but had little relationship with anthocyanin contents

Dark modes governed by translational-symmetry-protected bound states in the continuum in symmetric dimer lattices

Creating nonradiating dark modes is key to achieving high-Q resonance in dielectric open cavities. The concept of photonic bound states in the continuum (BIC) offers an efficient method to suppress radiative loss through symmetry engineering. Structural reflection symmetry (RS) has been widely utilized to construct BICs in asymmetric metasurfaces. In this paper, we show that the radiation channel of translational-symmetry (TS) protected BIC in 1D symmetric dimer lattice could be unlocked by dimer spacing perturbation. A semi-analytical coupled mode analysis reveals that the total radiation suppression of the TS-BIC is due to the elimination of the first Fourier harmonic component in the lattice parameters. TS-BIC mechanism could also be applied in a 2D symmetric dimer lattice, and BICs protected by TS are robust to RS breaking, and vice versa, providing a promising way to independently control the quality factor of two interacting BIC resonances. Our results suggest a new degree of freedom to engineer BICs as well as their interactions in dimer lattices tailored by different symmetries, and could provide new insight for realizing practical applications requiring high-Q resonances

Changes of the Anthocyanins and Antioxidant properties of Concord Grape (Vitis labrusca) Pomace After Acid Hydrolysis

Grape pomace contains high levels of valuable antioxidants such as anthocyanins and phenolic compounds that help prevent chronic diseases such as cardiovascular problems and cancers. In this study, Concord grape pomace was soaked in acidic solutions at different time intervals and pHs in a water bath at 80 oC. Five kinds of anthocyanins were released and identified in the pomace after acid hydrolysis. The releasing rate of anthocyanins and antioxidant activities of the acid hydrolyzed pomace extracts were determined by multitest systems. Different antioxidant assays including total antioxidant capacity (TAC), total phenolic content (TPC) and free radical scavenging activity (RSA) were used to evaluate the antioxidant properties of the acid hydrolyzed pomace extracts. The change in antioxidant capacity of the pomace extracts during hydrolysis was correlated with total phenolic content and free radical scavenging activity but had little relationship with anthocyanin contents

Divergent ring-opening coupling between cyclopropanols and alkynes under cobalt catalysis

Cobalt–diphosphine catalysts promote ring-opening coupling reactions between cyclopropanols and unactivated internal alkynes, affording either β-alkenyl ketones or multisubstituted cyclopentenol derivatives in good yields with good to excellent regioselectivities. The chemoselectivity between these β-alkenylation and [3 + 2] annulation reactions, which likely share a cobalt homoenolate as a key catalytic intermediate, is exquisitely controlled by the reaction conditions, with the solvent being a major controlling factor. The reactions are proposed to involve ring opening of cobalt cyclopropoxide into homoenolate, migratory insertion of the alkyne into the Co–C bond, and protodemetalation or intramolecular carbonyl addition of the resulting alkenylcobalt species. The feasibility of these reaction steps was supported by DFT calculations.MOE (Min. of Education, S’pore)Published versio

Dual-Band All-Optical Logic Gates by Coherent Absorption in an Amorphous Silicon Graphene Metasurface

The dual-band polarization-independent all-optical logic gate by coherent absorption effect in an amorphous silicon (a-Si) graphene metasurface is investigated theoretically and numerically. Taking the substrate effect into consideration, the coherent perfect absorption condition of the a-Si graphene metasurface is derived on the basis of the Cartesian multipole method. The coherent nearly perfect absorption of the a-Si graphene metasurface is realized by the interference of multipole moments and the interband transition of monolayer graphene, achieving peak values of 91% and 92% at 894.5 nm and 991.5 nm, respectively. The polarization independence of the coherent absorption is revealed due to the center symmetry of the structure of the a-Si graphene metasurface. The dual-band polarization-independent all-optical XOR and OR logic gates are implemented at 894.5 nm and 991.5 nm by the a-Si graphene metasurface based on the coherent nearly perfect absorption, which has the opportunity to be utilized in all-optical computing, all-optical data processing, and future all-optical networks