Antiaflatoxigenic and antioxidant activities of Garcinia extracts

A Comprehensive Review of the Phytochemical and Pharmacological Potential of an Evergreen Plant Garcinia cowa

Garcinia cowa of the Clusiaceae family, native to South-East Asia used in traditional medicine. It has antipyretic, antimicrobial, and many other biological activities. In this review, a thorough study of this plant's chemical constituents and pharmacological and therapeutic effects was conducted from the research articles from PubMed, Science Direct, Google Scholar, and Scopus from 1977 to 2022. Reported secondary metabolites are enriched with xanthones, phloroglucinols, depsidones, steroids, etc. α-mangostin, β-mangostin, cowaxanthone, rubraxanthone, cowanin, norcowanin, etc. represent the major xanthones. This article discusses the relationship between the different functional groups in xanthone compounds and their bioactivity against cancer, diabetes, bacteria, leishmania, malaria, and inflammation. This review is a comprehensive compendium of major bioactive molecules and its implication for human disease.

Screening of medicinal plants unraveled the leishmanicidal credibility of Garcinia cowa; highlighting Norcowanin, a novel anti-leishmanial phytochemical through in-silico study

Leishmaniasis, one of the most prevalent yet neglected parasitic causes of death, yearns for therapeutic control and treatment. Severely toxic and inefficient modern-day pentavalent antimonials, caters the search for naturally derived drugs, as efficient alternatives for disease treatment. The anti-promastigote activity of ten different plants selected for their ethnomedicinal properties revealed significant leishmanicidal capacity; the most potent being Garcinia cowa methanolic extract with an IC₅₀ value of 21.4 µg/ml. Garcinia cowa, a plant endemic to North-Eastern India that is of the Clusiaceae family, is replete with such medicinal qualities as antimicrobial, antiviral, antiparasitic, and antiproliferative activities. Computational biology with its tools such as molecular docking has opened new horizons aimed at a better understanding of biological systems, complexes, and their interactions, and subsequently drug discovery via in silico techniques. Therefore, an in-silico study was designed to evaluate the binding capability of six phytochemicals- cowanin, cowanol, cowaxanthone, norcowanin, rubraxanthone, and a basic xanthone, found in Garcinia cowa against Pentamidine, a synthetic anti-leishmanial drug. The active sites of three characteristic enzymes belonging to the Leishmania donovani parasite: O-acetylserine sulfhydrylase (OASS), Trypanothione reductase (TryR), and N-Myristoyltransferase (NMT) were chosen as target proteins. Results revealed lower binding energies and higher affinities, of nearly all the phytochemicals with respect to Pentamidine, indicating their leishmanicidal potential. Norcowanin showed the lowest average binding of - 9.8 kcal/mol against all the three enzymes under study.

Protective effect of standardised fruit extract of Garcinia cowa Roxb. ex Choisy against ethanol induced gastric mucosal lesions in Wistar rats

BACKGROUND AND AIM

The fruit of Garcinia is a rich and valuable source of bioactive compounds and is traditionally used for treating wounds and ulcers. The present study was carried out to investigate the protective effect of chromatographically standardized fruit extract of Garcinia cowa (GCE) on ethanol-induced gastric lesions in rats and its possible mechanisms.

METHODS

The effect of GCE (200 and 400 mg/kg body weight) was evaluated by determining various gastric ulcer parameters like gastric wall mucus, non-protein sulfhydryls (NP-SH) content, microvascular permeability, endogenous antioxidant enzyme, and gastric histopathological study.

RESULTS AND CONCLUSIONS

Oral administration of GCE at doses of 200 and 400 mg/kg exhibited significant (p < .01) dose-dependent inhibition of ulcer index by 18.94-44.02%, respectively. Pre-treatment of rats with GCE (400 mg/kg) significantly restored the depleted gastric wall mucus level by 34.09% and NP-SH content by 33.35% induced by ethanol administration. In addition, GCE (400 mg/kg) showed a significant decrease in microvascular permeability of Evans Blue by 47.43%, rationalizing its protective effect. Furthermore, a significant increase in oxidative enzyme levels with reduction in malondialdehyde level and elevation of superoxide dismutase (SOD) activity was observed in the GCE treated group as compared to the ulcer control group. The histopathological assessment also confirmed the protective nature of GCE. HPTLC analysis showed the presence of 0.27%, 0.11% w/w gallic acid, and amentoflavone, respectively in GCE. The content of α-mangostin and xanthochymol in the G. cowa extract sample quantified by HPLC-PDA method was 0.72 and 8.46%, respectively. The results obtained indicate that the protective effect of GCE against gastric ulcers in rats through multiple actions confirmed by the reduction of oxidative stress and restoration of adhered gastric mucus, NP-SH content, and histological architecture.KEY MESSAGESEthanol is the most typical ulcerogenic agent and has been shown to extend the risk of ulcer in humans.Natural products are promising alternative medication for the development of new drugs to regulate gastrointestinal diseases.Garcinia cowa protects the gastric mucosa through multiple actions that include restoration of adhered gastric mucus and inhibition of lipid peroxidation.

DNA Repair Biosensor-Identified DNA Damage Activities of Endophyte Extracts from Garcinia cowa

Recent developments in chemotherapy focus on target-specific mechanisms, which occur only in cancer cells and minimize the effects on normal cells. DNA damage and repair pathways are a promising target in the treatment of cancer. In order to identify novel compounds targeting DNA repair pathways, two key proteins, 53BP1 and RAD54L, were tagged with fluorescent proteins as indicators for two major double strand break (DSB) repair pathways: non-homologous end-joining (NHEJ) and homologous recombination (HR). The engineered biosensor cells exhibited the same DNA repair properties as the wild type. The biosensor cells were further used to investigate the DNA repair activities of natural biological compounds. An extract from Phyllosticta sp., the endophyte isolated from the medicinal plant Garcinia cowa Roxb. ex Choisy, was tested. The results showed that the crude extract induced DSB, as demonstrated by the increase in the DNA DSB marker γH2AX. The damaged DNA appeared to be repaired through NHEJ, as the 53BP1 focus formation in the treated fraction was higher than in the control group. In conclusion, DNA repair-based biosensors are useful for the preliminary screening of crude extracts and biological compounds for the identification of potential targeted therapeutic drugs.

Construction and Application of a Database for a Five-Dimensional Identification of Natural Compounds in Garcinia Species by Means of UPLC-ESI-TWIMS-TOF-MS: Introducing Gas Phase Polyphenol Conformer Drift Time Distribution Intensity Ratios

Thirty-four reference compounds from G. buchananii were analyzed by means of UPLC-ESI-IMS-TOF-MS to build a database consisting of retention time, accurate m/ z of precursors and fragment ions, and rotationally averaged collision cross-sectional area (CCS). The CCS value of six selected compounds analyzed in bark extract in different concentrations and solvent systems showed excellent intra- and interday precision (RSD ≤ 0.9%). The established database was applied on different organs of G. buchananii as well as G. kola, G. mangostana, and G. cambogia enabling a fast and reliable identification of these natural bioactives. For several compounds, more than one drift time species could be highlighted, which we propose to be hydrogen bond stabilized rotational isomers transferred from solution to gas phase. We used all CCS values of one compound, and we propose to add also the intensity ratio of the conformers as a new and additional characteristic compound parameter in compound identification/screening/database applications to reduce dereplication and false positives and to strengthen the identification.

Fukugiside, a biflavonoid from Garcinia travancorica inhibits biofilm formation of Streptococcus pyogenes and its associated virulence factors

PURPOSE

Streptococcus pyogenes, a notorious human pathogen thatis responsible for various invasive and non-invasive diseases, possesses multiple virulence armaments, including biofilm formation. The current study demonstrates the anti-biofilm and anti-virulence potential of fukugiside, a biflavonoid isolated from Garciniatravancorica, against S. pyogenes.

METHODOLOGY

The anti-biofilm activity of fukugiside was assessed and established using microdilution and microscopic analysis. Biochemical assays were performed to assess the effects of fukugiside on important virulence factors, which were further validated using quantitative real-time PCR and in vivo analysis in Caenorhabditis elegans.

RESULTS

Fukugiside exhibited concentration-dependent biofilm inhibition (79 to 96 %) against multiple M serotypes of S. pyogenes (M1, M56, M65, M74, M100 and st38) with a minimum biofilm inhibitory concentration of 80 µg ml^-1. Electron microscopy and biochemical assay revealed a significant reduction in extracellular polymeric substance production. The results for the microbial adhesion to hydrocarbon assay, extracellular protease quantification and differential regulation of the dltA, speB, srv and ropB genes suggested that fukugiside probably inhibits biofilm formation by lowering cell surface hydrophobicity and destabilizing the biofilm matrix. The enhanced susceptibility to phagocytosis evidenced in the blood survival assay goes in unison with the downregulation of mga. The downregulation of important virulence factor-encoding genes such as hasA, slo and col370 suggested impaired virulence. In vivo analysis in C. elegans evinced the non-toxic nature of fukugiside and its anti-virulence potential against S. pyogenes.

CONCLUSION

Fukugiside exhibits potent anti-biofilm and anti-virulence activity against different M serotypes of S. pyogenes. It is also non-toxic, which augurs well for its clinical application.

Antiaflatoxigenic and Antimicrobial Activities of Schiff Bases of 2-Hydroxy-4-methoxybenzaldehyde, Cinnamaldehyde, and Similar Aldehydes

2-Hydroxy-4-methoxybenzaldehyde (HMBA) is a nontoxic phenolic flavor from dietary source Decalipus hamiltonii and Hemidesmus indicus. HMBA is an excellent antimicrobial agent with additional antiaflatoxigenic potency. On the other hand, cinnamaldehyde from cinnamon is a widely employed flavor with significant antiaflatoxigenic activity. We have attempted the enhancement of antiaflatoxigenic and antimicrobial properties of HMBA, cinnamaldehyde, and similar molecules via Schiff base formation accomplished from condensation reaction with amino sugar (d-glucamine). HMBA derived Schiff bases exhibited commendable antiaflatoxigenic activity at the concentration 0.1 mg/mL resulting in 9.6 ± 1.9% growth of Aspergillus flavus and subsequent 91.4 ± 3.9% reduction of aflatoxin B₁ with respect to control.

Oligomeric Procyanidins (OPCs) Inhibit Procollagen Type I Secretion of Fibroblasts

Wound healing is composed of a complex process that requires harmonies of various cell populations where fibroblasts play the main role. Oligomeric procyanidins (OPC) are main components of grape (Vitis vinifera) seed extracts, and recent studies showed OPC's effects on inflammation, cell migration, and proliferation. We investigated the effect of OPC on fibroblasts to regulate wound healing process. Human dermal fibroblast known as Hs27 cells were treated with various concentrations of OPC (0, 2.5, 5, 10, and 20 μg/μl). Cell cytotoxicity was evaluated by the Cell Counting Kit assay, and the expression levels of secreted procollagen were analyzed. Procollagen levels in OPC treated cells exposed to transforming growth factor beta 1 (TGF-β1) or ascorbic acid were evaluated using Western blot and immunocytochemistry. Relative mRNA expressions of procollagen, molecular chaperone such as HSP47, P4H were determined by real-time PCR in OPC treated cells. OPC showed no cytotoxicity on Hs27 cells at every concentration but inhibited procollagen secretion in a dose-dependent manner. The inhibitory effect also appeared under TGF-β1 induced collagen overproduction. Immunocytochemistry showed that higher levels of intracytoplasmic procollagen were accumulated in TGF-β1 treatment group, whereas ascorbic acid induced a release of accumulated procollagen under OPC treatment. The mRNA expressions of procollagen, molecular chaperone were not affected by OPC, but procollagen level was increased when exposed to TGF-β1. OPC inhibits procollagen secretion from fibroblasts with no effects on cell proliferations even under the environment of TGF-β1-induced collagen overproduction. OPC could regulate the diseases and symptoms of abnormal overabundant collagen production.

ANTIBACTERIAL ACTIVITY STUDY OF ACTIVE FRACTION FROM CHICK WEED PLANTS (Ageratum Conyzoides L.) AGAINST Bacillus Subtilis AND Vibrio Cholerae

The purpose of this research to determine the fractions of Chick Weed which has strong antibacterial activity  against bacteria test categories of Bacillus subtilis and Vibriocholerae.determine the value of the minimum in hibitory concentration(MIC) of the active fraction antibacterial Chick Weed.This research was carried out in August up to November 2016. The method used in this study  were extracted by maceration, fractionation by liquid-liquid fractionation, separation by column chromatography fractions, antibacterial activity test by theKirby-Bauermethod, while the determination of minimum in hibitory concentration by dilution broth,with test bacteria Bacillus subtilis and Vibriocholerae.The data presented in tabular form based on the average value and percent.The results of this study showed that the methanol extract Chick Weed active against test bacteria Bacillus subtilis and Vibrio cholerae. Fractionation which has strong category to standard antibiotics are methanol fraction by fraction column S4.The concentration MIC1000;500;250;125;62.5;31.2515.62; 7.81 ppm. The minimum in hibitory concentration column fractions S4 to test bacteria Vibrio cholerae of 62.5 ppm gives half the antibacterial activity of the antibacterial activity of standard antibiotics streptomycin and penicillin,tetracycline while giving a quarter activity. It can be concluded that the active fraction of methanol extractisa methanol fraction by fraction column S4 to test bacteria Vibrio cholerae.Keywords: Chick Weed, Minimum Inhibitory Concentration (MIC), active compound, Bacillus subtilis, Vibriocholera.

Simultaneous determination of four aflatoxins and ochratoxin A in ginger after inoculation with fungi by ultra-fast liquid chromatography-tandem mass spectrometry

BACKGROUND

Aflatoxins (AFs) and ochratoxin A (OTA) have been detected frequently in food, agricultural products and traditional Chinese medicines, and their presence poses serious health and economic problems worldwide. Ginger can easily be polluted with mycotoxins. In this study, ginger samples were cultivated for 15 days after inoculation with fungi and were prepared based on ultrasound-assisted solid-liquid extraction using methanol/water followed by immunoaffinity column clean-up and analysed by ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) for AFs and OTA.

RESULTS

The limits of detection and quantification of AFs and OTA were 0.04-0.30 µg mL(-1) and 0.125-1.0 µg mL(-1) , respectively. The recoveries were 82.0-100.2%. After 15 days' cultivation, no macroscopic mildew was found in ginger. But, the content of AFB1 expressed an increasing trend in ginger, peel [less than the limit of quantification (LOQ)] to the innermost layer (51.86 µ mL(-1) ), AFB2 was only detected in the innermost layer at the level of 0.87 µ mL(-1) . A small amount (

CONCLUSION

The developed method was successfully applied to analyse five mycotoxins, and has many advantages including rapid determination and high sensitivity. Meanwhile, in practice, more attention should be paid to the safety and quality of ginger. © 2016 Society of Chemical Industry.

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Key Words

• UFLC-MS/MS
• fungi inoculation
• ginger
• mycotoxins

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MESH Headings

• Aflatoxins/analysis
• Aflatoxins/chemistry
• Aflatoxins/metabolism
• Aspergillus/metabolism
• Chromatography, High Pressure Liquid/methods
• Food Contamination/analysis
• Food Microbiology
• Food Technology/methods
• Fungi/metabolism
• Zingiber officinale/chemistry
• Zingiber officinale/metabolism
• Zingiber officinale/microbiology
• Limit of Detection
• Ochratoxins/analysis
• Ochratoxins/chemistry
• Ochratoxins/metabolism
• Tandem Mass Spectrometry/methods
• Ultrasonics/methods

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Affiliation(s)

Ying Yang School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
Jing Wen School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
Weijun Kong Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
Qiutao Liu Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China Pharmacy College, Liaoning Medical University, Jinzhou, Liaoning 121001, China
Hongli Luo School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China
Jian Wang School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
Meihua Yang Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100193, China

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Structural Analysis and Biological Toxicity of Aflatoxins B1 and B2 Degradation Products Following Detoxification by Ocimum basilicum and Cassia fistula Aqueous Extracts

This study showed the comparison between Ocimum basilicum and Cassia fistula (leaves and branch) aqueous extracts for their ability to detoxify of aflatoxins B1 and B2 (AFB1; 100 μg L(-1) and AFB2; 50 μg L(-1)) by In Vitro assays and decontamination studies. Results indicated that O. basilicum leaves extract was found to be highly significant (P < 0.05) in degrading AFB1 and AFB2, i.e., 90.4 and 88.6%, respectively. However, O. basilicum branch, C. fistula leaves and branch extracts proved to be less efficient in degrading these aflatoxins, under optimized conditions, i.e., pH 8, temperature 30°C and incubation period of 72 h. Moreover the antifungal activity of these plants extracts were also tested. The findings depicted that O. basilicum leaves extract showed maximum growth inhibition of aflatoxigenic isolates, i.e., 82-87% as compared to other tested plants extracts. The structural elucidation of degraded toxin products by LCMS/MS analysis showed that nine degraded products of AFB1 and AFB2 were formed. MS/MS spectra showed that most of the products were formed by the removal of double bond in the terminal furan ring and modification of lactone group indicating less toxicity as compared to parent compounds. Brine shrimps bioassay further confirmed the low toxicity of degraded products, showing that O. basilicum leaves extract can be used as an effective tool for the detoxification of aflatoxins.

Structural Elucidation and Toxicity Assessment of Degraded Products of Aflatoxin B1 and B2 by Aqueous Extracts of Trachyspermum ammi

In this study aqueous extract of seeds and leaves of Trachyspermum ammi were evaluated for their ability to detoxify aflatoxin B1 and B2 (AFB1; 100 μg L(-1) and AFB2; 50 μg L(-1)) by in vitro and in vivo assays. Results indicated that T. ammi seeds extract was found to be significant (P < 0.05) in degrading AFB1 and AFB2 i.e., 92.8 and 91.9% respectively. However, T. ammi leaves extract proved to be less efficient in degrading these aflatoxins, under optimized conditions i.e., pH 8, temperature 30°C and incubation period of 72 h. The structural elucidation of degraded toxin products by LCMS/MS analysis showed that eight degraded products of AFB1 and AFB2 were formed. MS/MS spectra showed that most of the products were formed by the removal of double bond in the terminal furan ring and modification of lactone group indicating less toxicity as compared to parent compounds. Brine shrimps bioassay further confirmed the low toxicity of degraded products, showing that T. ammi seeds extract can be used as an effective tool for the detoxification of aflatoxins.

Changes in serum cytokine levels, hepatic and intestinal morphology in aflatoxin B1-induced injury: modulatory roles of melatonin and flavonoid-rich fractions from Chromolena odorata

Aflatoxins are known to produce chronic carcinogenic, mutagenic, and teratogenic effects, as well as acute inflammatory effects, especially in the gastrointestinal tract. The potentials of the flavonoid-rich extract from Chromolena odorata (FCO) and melatonin (a standard anti-oxidant and anti-inflammatory agent) against aflatoxin B1 (AFB1)-induced alterations in pro-inflammatory cytokine levels and morphology of liver and small intestines were evaluated in this study. We utilized Wistar albino rats (200-230 g) randomly divided into five groups made up of group A, control rats; group B, rats given AFB1 (2.5 mg/kg, intraperitoneal) twice on days 5 and 7; rats in groups C, D, and E were treated with melatonin (10 mg/kg, intraperitoneal) or oral doses of FCO1 (50 mg/kg) and FCO2 (100 mg/kg) for 7 days, respectively, along with AFB1 injection on days 5 and 7. Serum levels of interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) were determined using commercial ELISA kits and histopathological evaluation of the liver, duodenum, and ileum were also carried out. We observed significant elevation (p < 0.05) in serum IL-1β correlating with hemorrhages and leucocytic and lymphocytic infiltration in the liver and intestines as evidences of an acute inflammatory response to AFB1 administration. All treatments yielded significant reduction (p < 0.05) in IL-1β levels, although TNF-α levels were not significantly altered in all rats that received AFB1, irrespective of the treatments. Melatonin and FCO2 produced considerable protection of hepatic tissues, although melatonin was not quite effective in protecting the intestinal lesions. Our findings suggest a modulation of cytokine expression that may, in part, be responsible for the abilities of C. odorata or melatonin in amelioration of hepatic and intestinal lesions associated with aflatoxin B1 injury.

Antioxidant and antiplatlet aggregation properties of bark extracts of Garcinia pedunculata and Garcinia cowa

The bark extracts of Garcinia pedunculata and Garcinia cowa, which are abundant in the Northeastern regions of India, were screened for their antioxidant and in vitro antiplatelet aggregating activities. By β-carotene linoleate model for antioxidant assay, acetone extract of G. pedunculata and hexane extracts of G. cowa exhibited higher antioxidant activity (86.47 and 66.94 % respectively, at 25 ppm) than other extracts. Similar pattern was observed for superoxide radical scavenging method for antioxidant assay. The ethyl acetate extract of G. pedunculata and hexane extract of G. cowa exhibited higher antiplatelet aggregation capacity towards ADP induced platelet aggregation (IC50 0.16 and 0.43 ug, respectively) than other extracts.

Natural occurrence of mycotoxins in medicinal plants: a review

Medicinal plants are widely used as home remedies and raw materials for the pharmaceutical industries. Herbal remedies are used in the prevention, treatment and cure of disorders and diseases since ancient times. However, use of medicinal herbs may not meet the requirements of quality, safety and efficacy. During harvesting, handling, storage and distribution, medicinal plants are subjected to contamination by various fungi, which may be responsible for spoilage and production of mycotoxins. The increasing consumption of medicinal plants has made their use a public health problem due to the lack of effective surveillance of the use, efficacy, toxicity and quality of these natural products. The increase in use of medicinal plants may lead to an increase in the intake of mycotoxins therefore contamination of medicinal plants with mycotoxins can contribute to adverse human health problems and therefore represents a special hazard. Numerous natural occurrences of mycotoxins in medicinal plants and traditional herbal medicines have been reported from various countries including Spain, China, Germany, India, Turkey and from Middle East as well. This review discusses the important mycotoxins and their natural occurrences in medicinal plants and their products.

Investigations on the antifungal effect of nerol against Aspergillus flavus causing food spoilage

The antifungal efficacy of nerol (NEL) has been proved against Aspergillus flavus by using in vitro and in vivo tests. The mycelial growth of A. flavus was completely inhibited at concentrations of 0.8 μL/mL and 0.1 μL/mL NEL in the air at contact and vapor conditions, respectively. The NEL also had an evident inhibitory effect on spore germination in A. flavus along with NEL concentration as well as time-dependent kinetic inhibition. The NEL presented noticeable inhibition on dry mycelium weight and synthesis of aflatoxin B₁ (AFB₁) by A. flavus, totally restraining AFB₁ production at 0.6 μL/mL. In real food system, the efficacy of the NEL on resistance to decay development in cherry tomatoes was investigated in vivo by exposing inoculated and control fruit groups to NEL vapor at different concentration. NEL vapors at 0.1 μL/mL air concentration significantly reduced artificially contaminated A. flavus and a broad spectrum of fungal microbiota. Results obtained from presented study showed that the NEL had a great antifungal activity and could be considered as a benefit and safe tool to control food spoilage.

DFT/B3LYP Study of the Substituent Effects on the Reaction Enthalpies of the Antioxidant Mechanisms of Sesamol Derivatives in the Gas phase and water

In this paper, the study of various ortho and meta–substituted Sesamol derivatives is presented. The reaction enthalpies related to three antioxidant action mechanisms HAT, SET–PT, and SPLET for substituted Sesamols, have been calculated using the DFT/B3LYP method in gas phase and water. Calculated results show that electron-withdrawing substituents increase the bond dissociation enthalpy (BDE), ionization potential (IP), and electron transfer enthalpy (ETE), while electron-donating ones cause a rise in the proton dissociation enthalpy (PDE) and proton affinity (PA). In the ortho position, substituents show a larger effect on reaction enthalpies than in the meta position. In comparison with the gas phase, water attenuates the substituent effect on all reaction enthalpies. In the gas phase, BDEs are lower than PAs and IPs, i.e., HAT represents the thermodynamically preferred pathway. On the other hand, the SPLET mechanism represents the thermodynamically favored process in water. Results show that calculated enthalpies can be successfully correlated with Hammett constants (σm) of the substituted Sesamols. Furthermore, calculated IP and PA values for substituted Sesamols show linear dependence on the energy of the highest occupied molecular orbital (EHOMO).

An investigation into the supramolecular structure, solubility, stability and antioxidant activity of rutin/cyclodextrin inclusion complex

The formation of supramolecular inclusion complexes between rutin and four cyclodextrins, namely β-cyclodextrin (β-CD), (2-hydroxypropyl)-α-cyclodextrin (HP-α-CD), (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) and (2-hydroxypropyl)-γ-cyclodextrin (HP-γ-CD), and the effects of the complexation on the stability and antioxidant activity of rutin were investigated. Results from phase-solubility studies showed that rutin formed 1:1 stoichiometric inclusion complexes with HP-α-CD, β-CD, HP-β-CD and HP-γ-CD; the complexes formed with HP-γ-CD and HP-β-CD had the greatest stability constants, followed by β-CD and HP-α-CD. Thermodynamic studies demonstrate that the inclusion of rutin into HP-β-CD was an exothermic process which occurred spontaneously. Two-dimensional rotating-frame nuclear Overhauser effect spectroscopy (2D ROESY) (1)H NMR analyses show that the A ring of rutin was the part of the molecule that most likely inserted into the cavity of HP-β-CD, thus forming a supramolecular inclusion complex. Formation of such an inclusion complex conferred moderate degrees of protection to rutin from degradation by heat and UV radiation during storage, and significantly enhanced its antioxidant capacity as determined by three different procedures.

Isolation and structure elucidation of highly antioxidative 3,8″-linked biflavanones and flavanone-C-glycosides from Garcinia buchananii bark

The aim of this study was to identify antioxidants from Garcinia buchananii bark extract using hydrogen peroxide scavenging and oxygen radical absorbance capacity (ORAC) assays. LC-MS/MS analysis, 1D- and 2D-NMR, and circular dichroism (CD) spectroscopy led to the unequivocal identification of the major antioxidative molecules as a series of three 3,8″-linked biflavanones and two flavanone-C-glycosides. Besides the previously reported (2R,3R,2″R,3″R)-naringenin-C-3/C-8″ dihydroquercetin linked biflavanone (GB-2; 4) and (2R,3S,2″R,3″R)-manniflavanone (3), whose stereochemistry has been revised, the antioxidants identified for the first time in Garcinia buchananii were (2R,3R)-taxifolin-6-C-β-D-glucopyranoside (1), (2R,3R)-aromadendrin-6-C-β-D-glucopyranoside (2), and the new compound (2R,3S,2″S)-buchananiflavanone (5). The H₂O₂ scavenging and the ORAC assays demonstrated that these natural products have an extraordinarily high antioxidative power, especially (2R,3S,2″R,3″R)-manniflavanone (3) and GB-2 (4), with EC₅₀ values of 2.8 and 2.2 μM, respectively, and 13.73 and 12.10 μmol TE/ μmol. These findings demonstrate that G. buchananii bark extract is a rich natural source of antioxidants.

Effect of antioxidant mixtures on growth and ochratoxin a production of Aspergillus section Nigri species under different water activity conditions on peanut meal extract agar

The effect of mixtures of antioxidants butylated hydroxyanisol (BHA) and propyl paraben (PP) on lag phase, growth rate and ochratoxin A (OTA) production by four Aspergillus section Nigri strains was evaluated on peanut meal extract agar (PMEA) under different water activities (a(w)). The antioxidant mixtures used were: BHA + PP (mM), M1 (0.5 + 0.5), M2 (1.0 + 0.5), M3 (2.5 + 0.5), M4 (0.5 + 1.0), M5 (1.0 + 1.0), M6 (2.5 + 1.0), M7 (5.0 + 2.5) and M8 (10 + 2.5). The mixture M8 completely suppressed mycelial growth for all strains. A significant stimulation in OTA production was observed with mixtures M1 to M5 mainly at the highest a(w); whereas M6, M7 and M8 completely inhibited OTA production in all strains assayed; except M6 in A. carbonarius strain (RCP G). These results could enable a future intervention strategy to minimize OTA contamination.

Natural maize phytochemicals for control of maize mycoflora and aflatoxigenic fungi

This research was undertaken to evaluate the effects of the natural phytochemicals trans-cinnamic acid (CA) alone at concentrations of 20 and 25 mM, ferulic acid (FA) at concentration of 30 mM and two mixtures, CA-FA (20+30 mM) and CA-FA (25+30 mM) on natural maize mycoflora, Aspergillus section Flavi population and aflatoxin B1 production. These studies were carried out in maize grain in relation to a water activity of 0.99, 0.97 and 0.94. CA at 25 mM and the mixture CA-FA (25+30 mM) were the most effective treatments at inhibiting natural maize mycoflora at all aw assayed after 11 and 35 days of incubation at 25 °C. In general, 20 mM CA caused complete inhibition of Aspergillus section Flavi population at all aw values tested during all incubation period without an additional inoculum. 20 mM CA and 25 mM CA showed the major inhibitory effect on aflatoxin B1 accumulation of control and Aspergillus section Flavi additionally inoculated during all incubation periods. The data showed that CA and FA could be considered as effective fungitoxicants for natural maize mycoflora and aflatoxigenic fungi in the aw range 0.99 to 0.94. The information obtained shows promise for controlling aflatoxigenic fungi in stored maize.