Stilbene Levels in the Tissue and Juice of Muscadine Grapes (Vitis rotundifolia Michx.)

Abstract

Stilbenes are secondary metabolites of a class of non-flavanoid phenolics found in certain species of Vitis. This class of compounds includes resveratrol and a resveratrol glucoside called piceid that exists in trans and cis forms. This study was undertaken to determine the cis and trans forms of both resveratrol and piceid in the skin, pulp, seeds, and juice of nine cultivars of muscadine grapes and three cultivars of Vitis labruscana. Juice samples of the muscadine cultivars ‘Fry’, ‘Hunt’, ‘Magnolia’, ‘Watergate’, ‘Carlos’, ‘Noble’, and ‘Sweet Jenny’, and the V. labruscana cultivars ‘Albermarle’, ‘Miss Blanc’, ‘MidSouth’ and ‘Miss Blue’ were harvested at the full ripe stage and divided into two sub-samples. One subsample was used to extract juice and the other was divided into skins, pulp, and seeds. Sample analysis was performed using HPLC with a UV detector. Sample chromatagrams were compared with those of known standards for quantification. ‘Carlos’ and ‘Magnolia’ had the greatest total stilbene concentration in skin tissue and had bronze skin containing higher concentrations of total stilbenes than any of the black-skinned cultivars tested. Only one bronze skin cultivar, ‘Sweet Jenny’, had lower stilbenes than the dark skin cultivars. Piceid, cis piceid and resveratrol were found in the skins of all cultivars. ‘Carlos’ ‘Magnolia’, ‘Fry’ and ‘Albermarle’ muscadines contained cis resveratrol in the skins of the fruit. ‘Watergate’ was the only cultivar in which resveratrol was detected in seed tissue. ‘Sweet Jenny’ had the highest levels of cis piceid in seed tissue. ‘Albermarle’, ‘Carlos’ and ‘Sweet Jenny’ had significantly greater levels of cis picied in pulp tissue than all other cultivars.     

New biologically active compounds from Kenyan propolis

From propolis samples from Kenya, two new arylnaphtalene lignans were isolated, tetrahydrojusticidin B 1 and 6-methoxydiphyllin 2, along with four known phenolic compounds 5–8, found for the first time in propolis. The structures of the compounds were elucidated based on their spectral properties. The geranylstilbenes 7 and 8 demonstrated antibacterial activity against S. aureus, and the geranylflavon macarangin 6 possessed antiradical activity against DPPH radicals.     

Three New Resveratrol Derivatives from the Mangrove Endophytic Fungus Alternaria sp.

Three new resveratrol derivatives, namely, resveratrodehydes A–C (1–3), were isolated from the mangrove endophytic fungus Alternaria sp. R6. The structures of these compounds were elucidated by analysis of their MS, 1D and 2D NMR spectroscopic data. All compounds showed broad-spectrum inhibitory activities against three human cancer cell lines including human breast MDA-MB-435, human liver HepG2, and human colon HCT-116 by MTT assay (IC₅₀ < 50 μM). Among them, compounds 1 and 2 both exhibited marked cytotoxic activities against MDA-MB-435 and HCT-116 cell lines (IC₅₀ < 10 μM). Additionally, compounds 1 and 3 showed moderate antioxidant activity by DPPH radical scavenging assay.     

UPLC-MS/MS测定动物源性食品中3种二苯乙烯类激素残留

建立了动物源性食品中二苯乙烯类激素己烯雌酚、己烷雌酚和双烯雌酚残留的超高效液相色谱-串联质谱（UPLC-MS/MS）测定法。样品均质后,采用β-葡萄糖醛酸酶/芳基硫酸酯酶酶解,叔丁基甲基醚提取,硅胶固相萃取柱净化。采用UPLC-MS/MS多反应监测（MRM）模式检测,内标法定量。方法对己烯雌酚、己烷雌酚和双烯雌酚的检出限均为0.1μg/kg,定量限均为0.5μg/kg;在1.0、1.5、2.0μg/kg三个浓度添加水平,总体平均回收率为75.8%-110.0%,总体相对标准偏差为3.3%-13.2%。本法分析速度快,灵敏度高,重现性好,各项技术指标均满足国内外相关法规要求,可用于各种动物源性食品中二苯乙烯类激素己烯雌酚、己烷雌酚和双烯雌酚残留的快速检测。     

Effect of dietary supplementation with resveratrol on nutrient digestibility,methanogenesis and ruminal microbial flora in sheep

Two experiments were conducted to evaluate the effect of resveratrol on methanogenesis and microbial flora in Dorper × thin‐tailed Han cross‐bred ewes. In experiment 1, ten ewes (67.2 ± 2.24 kg BW) were assigned to two dietary treatments, a basal diet and a basal diet supplemented with resveratrol (0.25 g/head·day), to investigate the effect of resveratrol on nutrient digestibility and nitrogen balance. In experiment 2, six ewes (64.0 ± 1.85 kg BW) with ruminal cannulae were assigned to the identical dietary treatments used in experiment 1 to investigate supplementary resveratrol on ruminal fermentation and microbial flora using qPCR. The results showed that supplementary resveratrol improved the digestibility of organic matter (OM; p < 0.001), nitrogen (N; p = 0.007), neutral detergent fibre (NDF; p < 0.001) and acid detergent fibre (ADF; p < 0.001). The excretion of faecal N was reduced (p = 0.007), whereas that of urinary N increased (p = 0.002), which led to an unchanged N retention (p = 0.157). Both CO₂ and CH₄ output scaled to digestible dry matter (DM) intake decreased from 602.5 to 518.7 (p = 0.039) and 68.2 to 56.6 (p < 0.001) respectively. Ruminal pH (p = 0.341), ammonia (p = 0.512) and total volatile fatty acid (VFA) (p = 0.249) were unaffected by resveratrol. The molar proportion of propionate increased from 13.1 to 17.5% (p < 0.001) while that of butyrate decreased from 11.0 to 9.55% (p < 0.001). The ratio of acetate to propionate (A/P) decreased from 5.44 to 3.96 (p < 0.001). Supplementary resveratrol increased ruminal population of Fibrobacter succinogenes, Ruminococcus albus and Butyrivibrio fibrisolvens (p < 0.001) while decreased protozoa and methanogens. In conclusion, dietary resveratrol inhibited methanogenesis without adversely affecting ruminal fermentation.     

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为探明何首乌主要活性成分二苯乙烯苷在非生物因子胁迫下的变化,为人工栽培调控提供参考.采用UV-C照射、茉莉酸甲酯和乙烯利喷施胁迫处理遗传背景一致的何首乌组培苗.结果表明:用茉莉酸甲酯溶液处理何首乌组培苗,0.20×10-3mol/L溶液能有效诱导二苯乙烯苷的产生,根中的二苯乙烯苷含量增加极显著,茎中略有下降,叶中略有升高,但不显著;0.25×10-3 mol/L溶液抑制根、茎中的二苯乙烯苷的生物合成,且根中的下降量与对照相比达极显著水平,叶中的量略有增加,但不显著.用乙烯利溶液喷施何首乌组培苗,250 mg/L溶液处理的组培苗根和茎中的二苯乙烯苷增加量与对照相比达极显著水平,叶中略有升高,但不显著;300 mg/L溶液处理根和茎中的二苯乙烯苷的生物合成均受抑制,且根中的下降量与对照相比达极显著水平,叶中含量略微增加,但不显著.用UV-C照射刺激何首乌组培苗,10 min/d持续处理5d,何首乌植株根、茎中二苯乙烯苷的生物合成均被抑制,与对照相比达极显著水平,叶中略有上升但不显著;20 min/d处理5d时,何首乌植株根、茎、叶中的二苯乙烯苷的生物合成均被抑制,且与对照相比,根和茎中的下降量均达极显著水平.二苯乙烯苷作为芪类化合物,在外界因子胁迫下其生物合成会被诱导合成或抑制.