Papers by Amy Y . H . Saik
Valorization of Agri-Food Wastes and By-Products, 2021
Abstract Fruit and vegetable processing industries produce millions of tons of waste annually wor... more Abstract Fruit and vegetable processing industries produce millions of tons of waste annually worldwide. Most fruit and vegetable wastes such as peels, pomace, seeds, stalks, leaves, and pods end up in landfills or dumped in rivers, causing environmental hazards. Only a small fraction is valorized as livestock feed, sources of bioactive compounds/pigments, biofuel production, and soil improvement material. Bioactive pigments are colored compounds that have potential health benefits for humans and can be obtained from animals, plants, or microorganisms, such as chlorophylls, carotenoids, anthocyanins, and betalains. Bioactive pigments can be used as food additives, antioxidants, color intensifiers, natural colorants, or as substrates for the generation of value-added products. In this chapter, the extraction and utilization of bioactive pigments such as anthocyanins, betalains, and carotenoids from selected fruit and vegetable (i.e., grape, red beet, and tomato) wastes are discussed.
Biotechnology Letters, 2016
Objectives: To investigate the lipase-catalyzed acylation of quercetin with oleic acid using Cand... more Objectives: To investigate the lipase-catalyzed acylation of quercetin with oleic acid using Candida antarctica lipase B. Results: Three acylated analogues were produced: quercetin 4′-oleate (C 33 H 42 O 8 ), quercetin 3′,4′-dioleate (C 51 H 74 O 9 ) and quercetin 7,3′,4′trioleate (C 69 H 106 O 10 ). Their identities were confirmed with UPLC-ESI-MS and 1 H NMR analyses. The effects of temperature, duration and molar ratio of substrates on the bioconversion yields varied across conditions. The regioselectivity of the acylated quercetin analogues was affected by the molar ratio of substrates. TLC showed the acylated analogues had higher lipophilicity (152% increase) compared to quercetin. Partition coefficient (log P) of quercetin 4′-oleate was higher than those of quercetin and oleic acid. Quercetin 4′-oleate was also stable over 28 days of storage. Conclusions: Quercetin oleate esters with enhanced lipophilicity can be produced via lipase-catalyzed reaction using C. antarctica lipase B to be used in topical applications.
This thesis examines the enzymatic modification of quercetin with cinnamic, oleic or palmitic aci... more This thesis examines the enzymatic modification of quercetin with cinnamic, oleic or palmitic acid. It identifies the lipophilicity, solubility, stability and cytotoxicity of the newly formed acylated quercetin analogues against human colon and oral cancer cells.
Journal of the American Oil Chemists' Society, 2020
Quercetin was acylated with palmitic acid, cata-lyzed by either Candida antarctica lipase B (CAL-... more Quercetin was acylated with palmitic acid, cata-lyzed by either Candida antarctica lipase B (CAL-B) or Pseudomonas cepacia lipase C (PCL-C) to produce querce-tin palmitate esters. The effects of various operating factors including incubation temperature, reaction duration, and molar ratio of substrates on the bioconversion yield, initial rate of reaction, and regioselectivity of the reactions were investigated. Three new esters were identified: quercetin 4 0-palmitate (C 31 H 40 O 8 , 540 g mol −1), quercetin 3 0 ,4 0-dipalmitate (C 47 H 70 O 9 , 778 g mol −1), and quercetin 7,3 0 ,4 0-tripalmitate (C 63 H 100 O 10 , 1016 g mol −1). The effects of incubation temperature, reaction duration, and molar ratio of substrates on bioconversion yields varied across the conditions. However, the highest bioconversion yield of 27.72 AE 1.64% was obtained with PCL-C, at day 7, incubation temperature of 60 C, quercetin:palmitic acid molar ratio of 1:20. The initial rate of reaction was significantly higher with PCL-C. However, regioselectivity was similar for both PCL-C-and CAL-B-catalyzed reactions with acyl-ation occurred successively at 4´-OH, 3´-OH, and 7-OH. Thin-layer chromatography analysis showed that the three quercetin palmitate esters possessed enhanced lipophilicity (134% higher than quercetin). Besides, in sil-ico investigation showed that quercetin 4 0-palmitate had a higher partition coefficient (log P) value than the parent compounds, indicating improved solubility. During gastro-intestinal tract simulation, quercetin palmitate esters were recovered in the range of 71.03% to 79.36% after digestion, which were significantly higher than quercetin at 40.43 AE 8.71%. Quercetin 4 0-palmitate was also found stable over 28 days of storage. Due to improved lipophilicity, solubility, and stability, quercetin 4 0-palmitate has the potential to be used in topical applications.
Biocatalysis and Biotransformation, 2016
Acylation of quercetin with cinnamic acid catalyzed by Candida antarctica lipase B (CAL-B) or Pse... more Acylation of quercetin with cinnamic acid catalyzed by Candida antarctica lipase B (CAL-B) or Pseudomonas cepacia lipase C (PCL-C) was investigated. Specifically, the effects of reaction duration, incubation temperature, and molar ratio of substrates on bioconversion yield, initial rate of reaction, and regioselectivity were investigated. Three new acylated quercetin analogues were produced: quercetin 4′-cinnamate (C 24 H 16 O 8), quercetin 3′,4′dicinnamate (C 33 H 22 O 9), and quercetin 7,3′,4′-tricinnamate (C 42 H 28 O 10). The effects of the lipase-catalyzed acylation conditions on the bioconversion yields varied across the conditions. The initial rate of reaction of acylation of quercetin with cinnamic acid catalyzed by CAL-B and PCL-C was similar. In the presence of CAL-B, acylation mainly took place at the C-4′-OH, generating mostly quercetin 4′-cinnamate; whereas with PCL-C, acylation mainly took place at both the 4′-and 3′-hydroxyls, generating quercetin 3′,4′-dicinnamate. Thin-layer-chromatography analysis showed that the three acylated quercetin analogues had higher lipophilicity when compared with quercetin. In silico investigation revealed that quercetin 4'-cinnamate and quercetin 3′,4′-dicinnamate are likely to be orally active pharmacological drugs.
Journal of the American Oil Chemists' Society, 2020
Quercetin was acylated with palmitic acid, cata-lyzed by either Candida antarctica lipase B (CAL-... more Quercetin was acylated with palmitic acid, cata-lyzed by either Candida antarctica lipase B (CAL-B) or Pseudomonas cepacia lipase C (PCL-C) to produce querce-tin palmitate esters. The effects of various operating factors including incubation temperature, reaction duration, and molar ratio of substrates on the bioconversion yield, initial rate of reaction, and regioselectivity of the reactions were investigated. Three new esters were identified: quercetin 4 0-palmitate (C 31 H 40 O 8 , 540 g mol −1), quercetin 3 0 ,4 0-dipalmitate (C 47 H 70 O 9 , 778 g mol −1), and quercetin 7,3 0 ,4 0-tripalmitate (C 63 H 100 O 10 , 1016 g mol −1). The effects of incubation temperature, reaction duration, and molar ratio of substrates on bioconversion yields varied across the conditions. However, the highest bioconversion yield of 27.72 AE 1.64% was obtained with PCL-C, at day 7, incubation temperature of 60 C, quercetin:palmitic acid molar ratio of 1:20. The initial rate of reaction was significantly higher with PCL-C. However, regioselectivity was similar for both PCL-C-and CAL-B-catalyzed reactions with acyl-ation occurred successively at 4´-OH, 3´-OH, and 7-OH. Thin-layer chromatography analysis showed that the three quercetin palmitate esters possessed enhanced lipophilicity (134% higher than quercetin). Besides, in sil-ico investigation showed that quercetin 4 0-palmitate had a higher partition coefficient (log P) value than the parent compounds, indicating improved solubility. During gastro-intestinal tract simulation, quercetin palmitate esters were recovered in the range of 71.03% to 79.36% after digestion, which were significantly higher than quercetin at 40.43 AE 8.71%. Quercetin 4 0-palmitate was also found stable over 28 days of storage. Due to improved lipophilicity, solubility, and stability, quercetin 4 0-palmitate has the potential to be used in topical applications.
Biotechnology Letters, 2017
Objectives To investigate the lipase-catalyzed acy-lation of quercetin with oleic acid using Cand... more Objectives To investigate the lipase-catalyzed acy-lation of quercetin with oleic acid using Candida antarctica lipase B. Results Three acylated analogues were produced: quercetin 4 0-oleate (C 33 H 42 O 8), quercetin 3 0 ,4 0-di-oleate (C 51 H 74 O 9) and quercetin 7,3 0 ,4 0-trioleate (C 69 H 106 O 10). Their identities were confirmed with UPLC–ESI–MS and 1 H NMR analyses. The effects of temperature, duration and molar ratio of substrates on the bioconversion yields varied across conditions. The regioselectivity of the acylated quercetin analogues was affected by the molar ratio of substrates. TLC showed the acylated analogues had higher lipophilic-ity (152% increase) compared to quercetin. Partition coefficient (log P) of quercetin 4 0-oleate was higher than those of quercetin and oleic acid. Quercetin 4 0-oleate was also stable over 28 days of storage. Conclusions Quercetin oleate esters with enhanced lipophilicity can be produced via lipase-catalyzed reaction using C. antarctica lipase B to be used in topical applications. Keywords Acylated quercetin Á Lipase Á Oleic acid Á Quercetin Á Quercetin 4 0-oleate Á Regioselectivity
Biocatalysis and biotransformation, 2016
Acylation of quercetin with cinnamic acid catalyzed by Candida antarctica lipase B (CAL-B) or Pse... more Acylation of quercetin with cinnamic acid catalyzed by Candida antarctica lipase B (CAL-B) or Pseudomonas cepacia lipase C (PCL-C) was investigated. Specifically, the effects of reaction duration, incubation temperature, and molar ratio of substrates on bioconversion yield, initial rate of reaction, and regioselectivity were investigated. Three new acylated quercetin analogues were produced: quercetin 40-cinnamate (C24H16O8), quercetin 30,40-dicinnamate (C33H22O9), and quercetin 7,30,40-tricinnamate (C42H28O10). The effects of the lipase-catalyzed acylation conditions on the bioconversion yields varied across the conditions. The initial rate of reaction of acylation of quercetin with cinnamic acid catalyzed by CALB and PCL-C was similar. In the presence of CAL-B, acylation mainly took place at the C-40-OH, generating mostly
quercetin 40-cinnamate; whereas with PCL-C, acylation mainly took place at both the 40- and 30-hydroxyls, generating quercetin 30,40-dicinnamate. Thin-layer-chromatography analysis showed that the three acylated quercetin analogues had
higher lipophilicity when compared with quercetin. In silico investigation revealed that quercetin 4’-cinnamate and quercetin 30,40-dicinnamate are likely to be orally active pharmacological drugs.
Books by Amy Y . H . Saik
Fruit and vegetable processing industries produce millions of tons of waste annually worldwide. M... more Fruit and vegetable processing industries produce millions of tons of waste annually worldwide. Most fruit and vegetable wastes such as peels, pomace, seeds, stalks, leaves, and pods end up in landfills or dumped in rivers, causing environmental hazards. Only a small fraction is valorized as livestock feed, sources of bioactive compounds/pigments, biofuel production, and soil improvement material. Bioactive pigments are colored compounds that have potential health benefits for humans and can be obtained from animals, plants, or microorganisms, such as chlorophylls, carotenoids, anthocyanins, and betalains. Bioactive pigments can be used as food additives, antioxidants, color intensifiers, natural colorants, or as substrates for the generation of value-added products. In this chapter, the extraction and utilization of bioactive pigments such as anthocyanins, betalains, and carotenoids from selected fruit and vegetable (i.e., grape, red beet, and tomato) wastes are discussed.
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Papers by Amy Y . H . Saik
quercetin 40-cinnamate; whereas with PCL-C, acylation mainly took place at both the 40- and 30-hydroxyls, generating quercetin 30,40-dicinnamate. Thin-layer-chromatography analysis showed that the three acylated quercetin analogues had
higher lipophilicity when compared with quercetin. In silico investigation revealed that quercetin 4’-cinnamate and quercetin 30,40-dicinnamate are likely to be orally active pharmacological drugs.
Books by Amy Y . H . Saik
quercetin 40-cinnamate; whereas with PCL-C, acylation mainly took place at both the 40- and 30-hydroxyls, generating quercetin 30,40-dicinnamate. Thin-layer-chromatography analysis showed that the three acylated quercetin analogues had
higher lipophilicity when compared with quercetin. In silico investigation revealed that quercetin 4’-cinnamate and quercetin 30,40-dicinnamate are likely to be orally active pharmacological drugs.