A phenolic glycoside from Flacourtia indica induces heme mediated oxidative stress in Plasmodium falciparum and attenuates malaria pathogenesis in mice.

BACKGROUND: Flacourtia indica is especially popular among the various communities of many African countries where it is being used traditionally for the treatment of malaria. In our previous report, we have identified some phenolic glycosides from the aerial parts of F. indica as promising antiplasmodial agents under in vitro conditions. PURPOSE: Antimalarial bioprospection of F. indica derived phenolic glycoside in Swiss mice (in vivo) with special emphasis on its mode of action. METHODS: Chloroquine sensitive strain of Plasmodium falciparum was routinely cultured and used for the in vitro studies. The in vivo antimalarial potential of phenolic glycoside was evaluated against P. berghei in Swiss mice through an array of parameters viz., hematological, biochemical, chemo-suppression and mean survival time. RESULTS: 2-(6-benzoyl-ß-d-glucopyranosyloxy)-7-(1α, 2α, 6α-trihydroxy-3-oxocyclohex-4-enoyl)-5-hydroxybenzyl alcohol (CPG), a phenolic glycoside isolated from the aerial parts of F. indica was found to exhibit promising antiplasmodial activity by arresting the P. falciparum growth at the trophozoite stage. Spectroscopic investigations reveal that CPG possesses a strong binding affinity with free heme moieties. In addition, these interactions lead to the inhibition of heme polymerization in malaria parasite, augmenting oxidative stress, and delaying the rapid growth of parasite. Under in-vivo condition, CPG exhibited significant antimalarial activity against P. berghei at 50 and 75mg/kg body weight through chemo-suppression of parasitemia and ameliorating the parasite induced inflammatory and oxidative (hepatic) imbalance in the experimental mice. CONCLUSION: CPG was found to be a potential antimalarial constituent of F. indica with an explored mechanism of action, which also offers the editing choices for developing CPG based antimalarial chemotypes.

Adjuvant effect of Asparagus racemosus Willd. derived saponins in antibody production, allergic response and pro-inflammatory cytokine modulation.

The study manifests the immunoadjuvant potential of saponin rich fraction from Asparagus racemosus in terms of cellular and humoral immune response that can be exploited against microbial infections. Asparagus racemosus (AR) has been attributed as an adaptogen and rasayana in traditional medication systems for enhancing the host defence mechanism. Spectrophotometric and HPTLC analysis ensured the presence of saponins. The saponin rich fractions were tested for immunoadjuvant property in ovalbumin immunised mice for the humoral response, quantified in terms of prolonged antibody production upto a duration of 56days. Proinflammatory cytokines (IL-6 and TNF) were estimated for the cellular immune response in LPS stimulated primary murine macrophages. The safety evaluation in terms of cytotoxicity and allergic response has also been evaluated through in-vitro (MTT) and in-vivo (IgE) respectively. ARS significantly inhibited the pro-inflammatory cytokines, in LPS stimulated murine macrophages with no intrinsic cytotoxicity. The significant increase in IgG production infers the utility of ARS for prolonged humoral response. Further, the antigen specific response of IL-12 at early stage and IgE titres also suggests the generation of cellular immune response and low allergic reaction respectively, as compared to conventional adjuvants. IL-6 and TNF fluctuations in LPS stimulated and non-stimulated macrophages along with IgG and IL-12 also confirmed the Th1/Th2 modulating effect of ARS. The study indicates potential effect of ARS as an adjuvant for the stimulation of cellular immune response in addition to generating a sustained adaptive response without any adverse effects paving way for further validation with pathogenic organisms.

A clerodane diterpene from Polyalthia longifolia as a modifying agent of the resistance of methicillin resistant Staphylococcus aureus.

BACKGROUND: Staphylococcus aureus infections are raising serious concern across the world. The effectiveness of conventional drugs is continuously decreasing due to global emergence of multidrug resistance (MDR) and therefore, new resistance-modifying agents (RMAs) are highly needed. HYPOTHESIS: Clerodane diterpene 16α-hydroxycleroda-3,13(14)-Z-dien-15,16-olide (CD) from leaves of Polyalthia longifolia (Sonn.) Thwaites (Annonaceae) as RAM will be useful in improving the current treatment strategies for staphylococcal infections. STUDY DESIGN: In the present study, we determine the resistance-modifying activity of CD using clinical isolates of MRSA. Further, the influence of CD on innate immune response was also evaluated in vitro and in vivo. The nature of potential interactions was determined by fractional inhibitory concentration indices (FICIs) calculated from microdilution assays and time-kill curves. RESULTS: The result of in vitro combination study showed that CD significantly reduced MIC of fluoroquinolones up to 16-folds (FICI 0.315-0.500), while in S. aureus infected Swiss albino mice model, combination of CD with norfloxacin, significantly (p<0.01, p<0.001) lowered the systemic microbial burden in blood, liver, kidney, lung and spleen tissues in comparison to CD, norfloxacin alone as well as untreated control. Flow cytometry analysis clearly showed that CD significantly inhibited EtBr efflux and extended post-antibiotic effect. In qRT-PCR analysis, CD alone as well as in combination, significantly modulated the expression of various efflux pump genes including norA up to 2-fold in clinical isolate MRSA-ST2071. Further, the in vitro combination study of the CD (10, 5, 2.5µg/ml) along with the norfloxacin (10µg/ml) depicted a significant decline in the pro-inflammatory cytokines, IL6 and TNF-α. In septic shock mice model, CD did not exhibit any significant changes in the level of pro-inflammatory cytokines. CONCLUSION: This is the first report on drug resistance-modifying potential of CD through inhibition of MDR efflux pump.

Synthesis of Gold Mediated Biocompatible Nanocomposite of Lactone Enriched Fraction from Sahadevi (Vernonia cinerea Lees): An Assessment of Antimalarial Potential.

Metals reduction into submicro/nano size through bhasma preparations for therapeutic use is well established in ancient traditional system of Indian medicines i.e. Ayurveda. Recently, nanotechnology has drawn the attention of researchers to develeope various size and shape nanoparicles / composite for number of applications.In this article, we report the enrichment of lactone enriched fraction (LEF) by liquid-liquid portioning of Vernonia cinerea metabolic extract and sysnthesis of mediated nano-gold composite (LEF-AuNPs) in single step process. The morphological characteristic based on transmission electron microscope (TEM) image analysis showed that LEF-AuNPs were predominantly nanopolygons and nanobots in shapes ranging from 50-200 nm in size. Abundance of phytochemicals in both LEF and LEF-AuNPs was dissimilar. In LEF, montanol- a diterpenoid, while in LEF-AuNPs, neophytadiene- a phytanes was the major compound. HPLC profile of relatively polar compounds also varied drastically. In-vitro biocompatibility, cytotoxicity [MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) based assay] and storage stabilitiy of LEF-AuNPs were evaluated. The moderate ability of LEF-AuNPs to restrict parasitaemia, extended mean survival time of mice infected with Plasmodium berghei and lack of any evident toxicity provides new opportunities for the safe delivery and applications of such nanocomposites in malaria therapy.