A mechanistic study on the inhibition of bacterial growth and inflammation by Nerium oleander extract with comprehensive in vivo safety profile.

BACKGROUND: Nerium oleander (L.) is well known traditionally used medicinal plant with several pharmacological activities. However, the anti-bacterial, anti-inflammatory activity and in vivo toxicity potential of floral parts of this plant are not reported. Therefore the present study was designed to investigate these activities of Nerium oleander ethanolic flower extract (NOEE) in different animal models. METHODS: Antimicrobial activity of plant extract was compared with five different antibiotics using the disk diffusion method. The time-killing kinetic assay and bacterial killing mechanism of NOEE were also performed. Anti-inflammatory activity was assessed using granuloma induced by cotton-pellet, rat paw edema induced by carrageenan and levels of different inflammatory biomarkers on healthy Wistar rats. The protein and mRNA expressions of nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) were also measured. Acute (14 days) and sub-acute (28 days) oral toxicity studies were also performed on healthy Sprague Dawley rats. RESULTS: NOEE produced highly significant (P < 0.005) and significant (P < 0.05) zones of inhibition at 30 mg/mL and 20 mg/mL respectively against most of the tested bacterial strains. NOEE produced a more drop in viable counts of Gram-negative isolates within 20 min. After 12 h exposure with NOEE, the SEM images of MRSA showed the destruction of cell membrane. NOEE showed highly significant (P < 0.005) anti-inflammatory activity in cotton-pellet and carrageenan inflammatory models. In addition, treatment with NOEE also decreased the production of NO, PGE2, TNF-α and IL-1ß in the rat paw after treated with carrageenan. Similarly, NOEE also suppressed the inducible nitric oxide synthase (iNOS), TNF-α, IL-1ß, and cyclooxygenase-2 (COX-2) mRNA expressions. It is also showed highly significant reduction in total leukocyte count (73.09%) and C-reactive protein levels (54.60%). NOEE also inhibited COX-1, COX-2, 5-LO and 12-LO in a highly significant manner. Moreover, acute and sub-acute toxicity studies of NOEE in rats confirm the toxicity with hepatotoxicity at higher doses (2000 mg/kg) i.e. four times greater than the therapeutic dose. CONCLUSION: It is concluded that crude flower extract of N. oleander is a potent antimicrobial and anti-inflammatory agent with no toxicity potential at therapeutic doses.

Hepatoprotective and antioxidant activity of Dicliptera bupleuroides Nees. extracts on paracetamol induced hepatotoxicity in rats.

Aim of this study to evaluate the safety profile, hepatoprotective and in-vivo antioxidant activities of Dicliptera bupleuroides Nees. Toxicity studies were conducted in human RBCs and DNA by using standard procedures. Acute hepatoprotective investigation was carried out in albino rats by treated with all six fractions of D. bupleuroides 350 mg/kg/day. ALT, AST, ALP and total bilirubin (TB) were performed. The n-hexane fraction (200 mg/kg/day) exhibited appropriate hepatoprotective activity hence subjected to chronic study (14 days). Paracetamol induced the hepatotoxicity (350mg/kg) and silymarin (50 mg/kg) was standard drug. Liver function tests, liver peroxidation tests and histopathological examination were performed at the end. Hexane fraction showed significant decrease in the level of ALT (88.1±7.8), AST (93.8±7.6), ALP (136.3±8.4) and TB (0.6±0.03) as compared to the standard drug (p>0.05). Rats treated with ethyl acetate fraction showed decrease in MDA (42.8±0.7) while GSH was found to be increased (107.7±1.8) against the toxic group (51.3±2.9), (73.6±4.0) respectively. All the drug extracts decreased the oxidative stress and protect the DNA from free hydroxyl radicals. DNA damage protection activity of these fractions is due to phytochemicals present in these fractions. These results indicate that the plant fractions possess significant hepatoprotective and antioxidant activities with no toxic effects.

Preparation of microemulsion containing Lycopersicon esculentum extract: In vitro characterization and stability studies.

Lycopene, the active component of Lycopersicon esculentum species, has been reported for the protecting capabilities against ultra-violet induced skin pigmentation, antioxygen and antityrosinase activities. In the present study, extract of tomato fruit was obtained from the Lycopersicon esculentum plant using solvent system comprised of hexaneethanol-acetone. The phyto chemical active constituent lycopene was then identified by spectrophotometric technique at 470nm. Micro emulsions were developed containing different ratio of water, isopropyl myristate (oil), tween 80 and propylene glycol as surfactant and co-surfactant respectively via pseudoternary phase diagram. Various physicochemical tests were performed including globular size, conductivity, viscosity, scanning electron microscopy (SEM), refractive index (RI) and pH measurement for the formulation characterization. Results of physical and chemical stability studies showed that the micro emulsion with proportion of surfactant: co-surfactant of 2:1 (Smix) was found to be optimized formulation and with enhanced stability. Therefore, concluded that the stability of the micro emulsion was dependent on the proportions of surfactant co-surfactant, water and oil in the preparation.

Assessment of killing kinetics assay and bactericidal mechanism of crude methanolic bark extract of Casuarina equisetifolia.

Casuarina equisetifolia L. is an important medicinal plant widely used to treat various diseases particularly ulcers, diabetes, cough, diarrhea and many infectious and skin diseases. The aim of this research study was to examine the killing mechanism and killing kinetics assay of methanolic bark extract of C. equisetifolia against some highly resistant human pathogens. The comparison on antibacterial activity of extract was firstly done with six different well reputed antibiotics using disk diffusion method. The broth dilution method was used to measure the MIC and MBC values. The mechanism of killing was identified by scanning electron microscopy (SEM) technique. Results showed that higher inhibitory zones were produced by methanolic plant extract than that of some tested antibiotics. The lower MIC and MBC values indicated the antibacterial potency of plant extract. The extract of C. equisetifolia produced a more drop in optical density of S. aureus, MRSA B. subtilis and S. epidermidis up to 12 hrs. The complete destruction of the cell membrane of MRSA was observed after 12 h treatment with plant extract. It is concluded that crude bark extract of C. equisetifolia is potent antimicrobial agent and produced both bacteriostatic and bactericidal effects. Its killing time was extremely faster especially against MRSA. The cell membrane rapturing is a suggested killing mechanism of plant extract.