Isolation, structure elucidation, antioxidative and immunomodulatory properties of two novel dihydrocoumarins from Aloe vera.

Annona muricata is a naturally occurring edible plant with wide array of therapeutic potentials. In India, it has a long history of traditional use in treating various ailments. The present investigation was carried out to characterize the phytochemicals present in the methanolic and aqueous leaf extracts of A. muricata, followed by validation of its radical scavenging and DNA protection activities. The extracts were also analyzed for its total phenolic contents and subjected to HPLC analysis to determine its active metabolites. The radical scavenging activities were premeditated by various complementary assays (DRSA, FRAP and HRSA). Further, its DNA protection efficacy against H2O2 induced toxicity was evaluated using pBR322 plasmid DNA. The results revealed that the extracts were highly rich in various phytochemicals including luteolin, homoorientin, tangeretin, quercetin, daidzein, epicatechin gallate, emodin and coumaric acid. Both the extracts showed significant (p < 0.05) radical scavenging activities, while methanolic extract demonstrated improved protection against H2O2-induced DNA damage when compared to aqueous extract. A strong positive correlation was observed for the estimated total phenolic contents and radical scavenging potentials of the extracts. Further HPLC analysis of the phyto-constituents of the extracts provides a sound scientific basis for compound isolation.

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Antioxidant, DNA protective efficacy and HPLC analysis of Annona muricata (soursop) extracts

Chlorin e6-based photosensitizers for photodynamic therapy and photodiagnosis.

According to the World Health Organization (WHO), cancer is the second-highest cause of mortality in the world, and it kills nearly 9.6 million people annually. Besides the fatality of the disease, poor prognosis, cost of conventional therapies, and associated side-effects add more burden to patients, post-diagnosis. Therefore, the search for alternatives for the treatment of cancer that are safe, multi-targeted, effective, and cost-effective has compelled us to go back to ancient systems of medicine. Natural herbs and plant formulations are laden with a variety of phytochemicals. One such compound is rhein, which is an anthraquinone derived from the roots of Rheum spp. and Polygonum multiflorum. In ethnomedicine, these plants are used for the treatment of inflammation, osteoarthritis, diabetes, and bacterial and helminthic infections. Increasing evidence suggests that this compound can suppress breast cancer, cervical cancer, colon cancer, lung cancer, ovarian cancer, etc. in both in vitro and in vivo settings. Recent studies have reported that this compound modulates different signaling cascades in cancer cells and can prevent angiogenesis and progression of different types of cancers. The present review highlights the cancer-preventing and therapeutic properties of rhein based on the available literature, which will help to extend further research to establish the chemoprotective and therapeutic roles of rhein compared to other conventional drugs. Future pharmacokinetic and toxicological studies could support this compound as an effective anticancer agent.

https://www.mdpi.com/1420-3049/25/10/2278/pdf

Therapeutic Emergence of Rhein as a Potential Anticancer Drug: A Review of Its Molecular Targets and Anticancer Properties.

Differences in pharmacokinetics and ex vivo antioxidant activity following intravenous and oral administrations of emodin to rats

The objective of this study was to investigate the ability of emodin (1), aloe-emodin (2), and rhein (3) to inhibit free-radical or reactive oxygen species (.OH, 1O2, H2O2) generated in cell-free systems using isoluminol and luminol-enhanced chemiluminescence and electronic absorption spectra. In the presence of 1, 2, and 3, a dose-dependent inhibition period was observed in this system as assayed by isoluminol-enhanced chemiluminescence (ILCL) with horseradish peroxidase (HRP), as well as by luminol-enhanced chemiluminescence (LCL) with H2O2 or ferrous iron. On the other hand, these hydroxyanthraquinones showed an efficient scavenging activity of galvanoxyl radical in ethanolic solutions. In a separate experiment, we observed the trapping of singlet oxygen (1O2) generated by rose bengal in the presence of 1, 2, or 3. These results suggest that emodin, aloe-emodin, and rhein scavenge reactive oxygen and free-radical species in the following decreasing order: emodin > rhein > aloe-emodin.

Antioxidant and Scavenging Activity of Emodin, Aloe-Emodin, and Rhein on Free-Radical and Reactive Oxygen Species

The absorption and fluorescence spectra of recently presented photosensitizer for photodynamic therapy “Radachlorin” are studied in different pH, solvents and in the presence of human serum albumin. Radachlorin is found to efficiently generate singlet oxygen when irradiated with visible light. The formation of singlet oxygen by photolysis of Radachlorin was evidenced by HPLC trapping 1O2 with furfuryl alcohol and 1,3-cyclohexadiene-1,4-diethanoate and by the histidine test. The photophysical properties of this novel photosensitizer are used to discuss its anti-tumoral photoactivity.

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Photophysical Properties of Novel PDT Photosensitizer Radachlorin in Different Media

The absorption and fluorescence spectrums of four antibacterial quinolones, namely, ciprofloxacin, norfloxacin, enoxacin, and cinoxacin, were studied in the presence of human serum albumin (HSA). Of the three fluoroquinolones studied, ciprofloxacin and norfloxacin were found to bind efficiently to HSA when irradiated with visible light, whereas the third, enoxacin, bound only moderately. On the other hand, cinoxacin, a nonfluorinated quinolone of the first generation, did not show any interaction with HSA. The findings were inferred by monitoring the evolution of the fluorescence spectrums of the solutions as a function of time. A direct relationship between the capacity of the photo-induced defluorination to produce aryl cation intermediates, and the subsequent binding reaction with HSA, was observed and is discussed.

Yrene Díaz

Papers

Antioxidant and Scavenging Activity of Emodin, Aloe-Emodin, and Rhein on Free-Radical and Reactive Oxygen Species

Photophysical Properties of Novel PDT Photosensitizer Radachlorin in Different Media

Photo-induced interaction of antibacterial quinolones with human serum albumin.