Anti-inflammatory, antioxidant, anti-tyrosinase and phenolic contents of four Podocarpus species used in traditional medicine in South Africa

Ethnopharmacological relevance

Species of Podocarpus are used traditionally in their native areas for the treatment of fevers, asthma, coughs, cholera, chest complaints, arthritis, rheumatism, venereal diseases and distemper in dogs.

Aims of the study

To investigate the antioxidant, anti-inflammatory and anti-tyrosinase activities of four Podocarpus species, Podocarpus elongatus, Podocarpus falcatus, Podocarpus henkelii and Podocarpus latifolius, used in traditional medicine in South Africa. Phytochemical analysis to determine the phenolic contents was also carried out.

Materials and methods

DPPH, FRAP and β-carotene-linoleic acid assays were used to determine the antioxidant/radical scavenging activities of these species. Anti-inflammatory activity of these species was assayed against two cyclooxygenase enzymes (COX-1 and COX-2). Tyrosinase inhibition activity was analysed using the modified dopachrome method with l-DOPA as the substrate. Phenolics were quantitatively determined using spectrophotometric methods.

Results

Stems of Podocarpus latifolius exhibited the lowest EC₅₀ (0.84 μg/ml) inhibition against DPPH. The percentage antioxidant activity based on the bleaching rate of β-carotene ranged from 96% to 99%. High ferric reducing power was observed in all the extracts. For COX-1, the lowest EC₅₀ value was exhibited by stem extracts of Podocarpus elongatus (5.02 μg/ml) and leaf extract of Podocarpus latifolius showed the lowest EC₅₀ against COX-2 (5.13 μg/ml). All extracts inhibited tyrosinase activity in a dose-dependent manner with stem extract of Podocarpus elongatus being the most potent with an EC₅₀ value of 0.14 mg/ml. The total phenolic content ranged from 2.38 to 6.94 mg of GAE/g dry sample.

Conclusion

The significant pharmacological activities observed support the use of these species in traditional medicine and may also be candidates in the search for modern pharmaceuticals in medicine, food and cosmetic industries.     

酢浆草提取物体外抗氧化活性研究

目的:探讨酢浆草提取物体外抗氧化活性。方法:采用DPPH法、FRAP法分别测定酢浆草水提取物清除DPPH自由基和总的抗氧化能力。结果:在实验的测定浓度范围之内,随着提取物浓度的增加,其对DPPH自由基的清除能力逐渐增强。2mg/mL酢浆草水提物对DPPH自由基的清除率达到67.144%。FRAP法测得20mg/mL酢浆草水提取液的总抗氧化能力为1.09mM。结论:酢浆草对DPPH自由基的清除效果良好,FRAP法测得酢浆草有一定的抗氧化能力,有进一步开发利用的价值。     

头状蓼提取物体外抗氧化活性研究

目的:研究头状蓼提取物的体外抗氧化活性。方法:以脂溶性维生素E及二丁基羟基甲苯(BHT)作对照,采用清除二苯代苦味酰基(DPPH)自由基、清除[2,2′-连氨-(3-乙基苯并噻唑啉-6-磺酸)二氨盐](ABTS)自由基和铁离子(Fe3+)还原/抗氧化能力(FRAP)测定法检测头状蓼石油醚、乙酸乙酯、甲醇提取物的体外抗氧化活性。结果:与头状蓼石油醚、乙酸乙酯提取物比较,头状蓼甲醇提取物清除DPPH自由基、清除ABTS自由基及还原Fe3+的能力较强。结论:头状蓼甲醇提取物具有较好的体外抗氧化活性。3种方法中,DPPH方法和ABTS方法相关性最高。     

Age-estimations of rats based on the average lateral diffusion constant of hepatocyte membrane proteins as revealed by fluorescence recovery after photobleaching

A method has been developed recently for measuring the average lateral diffusion constant of the proteins (D) in the cell membrane of hepatocytes in liver smears by fluorescence recovery after photobleaching (FRAP). A peroxide-induced autofluorescence (PIAF) of the membrane proteins was used as a fluorescent label. It has been established that D displays a significant negative linear correlation with age. The present paper describes age-estimations carried out on 12 male Fischer 344 rats (7–29 months of age) in so-called “blind experiments”: the operator knew only the sex of the rat, determined D from a small piece of the freshly removed liver, and estimated the age of the rat from the age-dependent regression line for D established previously on 16 other Fischer 344 male rats of various ages. There was a strong correlation of the estimated age with the actual one (r = 0.92), the slope of the regression line was 0.98 and its intercept differed from 0 by only 0.5 months. These results indicate that D may play a decisive role in the determination of membrane functions as predicted by the membrane hypothesis of aging.     

VAMP4 and its cognate SNAREs are required for maintaining the ribbon structure of the Golgi apparatus

Background

The Golgi apparatus is at a crossroads between anterograde and retrograde trafficking. It exhibits a twisted ribbon-like network in the juxtanuclear region of vertebrate cells. Vesicle-associated membrane protein 4 (VAMP4) is a unique v-SNARE expressed exclusively in trans-Golgi networks (TGN), where it regulates retrograde trafficking from the early endosome to the TGN with its cognate SNARE partners Syntaxin 6, Syntaxin 16, and Vti1a.

受体介导内吞引起的巨噬细胞膜磷脂流动性的改变

用光敏感磷脂荧光探针NBD－C6－HPC和FRAP（FluorescenceRecoveryAfterPhotobleaching）技术，测量了刀豆素A（ConA）、麦芽凝集素（WGA）、酵母多糖（Z．A）3种配体刺激前后巨噬细胞膜磷脂扩散系数及荧光恢复率的变化．结果显示，静息状态下膜磷脂的扩散系数D＝（11．37±1．22）×10－10cm2／s，荧光恢复率R＝86．2±7．7（％，漂白后200s）；3种配体刺激30min后，膜磷脂扩散系数和荧光恢复率（漂白后200s）分别为D＝（3．24±1．38）×10-10，R＝80.5±9．5（ConA）；D＝（5．30±1．55）×10－10，R＝50．9±9．8（WGA）;D＝（1．45±1．4）×10－10，R＝56.4±8．7（Z.A）．膜磷脂扩散系数的降低，与配体-受体复合体流动性的降低相关．     

Real‐time measurement of solute transport within the lacunar‐canalicular system of mechanically loaded bone: Direct evidence for load‐induced fluid flow

Since proposed by Piekarski and Munro in 1977, load‐induced fluid flow through the bone lacunar‐canalicular system (LCS) has been accepted as critical for bone metabolism, mechanotransduction, and adaptation. However, direct unequivocal observation and quantification of load‐induced fluid and solute convection through the LCS have been lacking due to technical difficulties. Using a novel experimental approach based on fluorescence recovery after photobleaching (FRAP) and synchronized mechanical loading and imaging, we successfully quantified the diffusive and convective transport of a small fluorescent tracer (sodium fluorescein, 376 Da) in the bone LCS of adult male C57BL/6J mice. We demonstrated that cyclic end‐compression of the mouse tibia with a moderate loading magnitude (–3 N peak load or 400 µε surface strain at 0.5 Hz) and a 4‐second rest/imaging window inserted between adjacent load cycles significantly enhanced (+31%) the transport of sodium fluorescein through the LCS compared with diffusion alone. Using an anatomically based three‐compartment transport model, the peak canalicular fluid velocity in the loaded bone was predicted (60 µm/s), and the resulting peak shear stress at the osteocyte process membrane was estimated (～5 Pa). This study convincingly demonstrated the presence of load‐induced convection in mechanically loaded bone. The combined experimental and mathematical approach presented herein represents an important advance in quantifying the microfluidic environment experienced by osteocytes in situ and provides a foundation for further studying the mechanisms by which mechanical stimulation modulates osteocytic cellular responses, which will inform basic bone biology, clinical understanding of osteoporosis and bone loss, and the rational engineering of their treatments. © 2011 American Society for Bone and Mineral Research.     

Mechanisms and genes involved in enhancement of HIV infectivity by tobacco smoke

HIV infection is more common among smokers than nonsmokers, and, remarkably, HIV-infected individuals are about 3 times more likely to smoke than the uninfected general population. However, the relationship between tobacco smoking and HIV/AIDS disease progression remains controversial. In this study, we demonstrate a potent enhancing effect of aqueous tobacco smoke extract (TSE) on HIV infectivity that is nicotine-independent. This increased infectivity is neither NF-κB mediated nor a direct result of oxidative stress, as it cannot be blocked by antioxidants. On the contrary, TSE itself was found to possess significant antioxidant potential, enabling it to protect the viability of both infected cells and HIV virions in the presence of peroxide. Assessment of TSE-induced alterations in cellular gene expression that may be involved in increasing HIV infectivity in T cells showed that TSE up-regulates some genes known to be capable of enhancing HIV and HCV infection, or protecting HIV, but down-regulates several genes involved in cellular defense and antigen presentation. These results demonstrate that tobacco smoke can enhance HIV infectivity, possibly by a combination of direct (antioxidant) and indirect (gene-based) mechanisms. This raises the concern that smoking may thereby increase the risk of acquisition or progression of HIV infection.