Effect of Aloe vera on nitric oxide production by macrophages during inflammation

The antioxidant activity of allylpyrocatechol is mediated via decreased generation of free radicals along with escalation of antioxidant mechanisms

Allylpyrocatechol (APC) is responsible for the antiinflammatory activity exhibited by the methanolic extract of leaves of Piper betle. As antiinflammatory compounds may display antioxidant properties and vice versa, we investigated the antioxidant effect of APC. APC effectively reduced phorbol-myristate-acetate-induced generation of reactive oxygen species and superoxide in murine peritoneal macrophages as well as inhibited Escherichia-coli-induced phagocytic activity of macrophages. Furthermore, pBluescript SK(+) plasmid DNA damage induced by addition of sodium ascorbate was attenuated by APC as it inhibited transformation of the supercoiled form to a relaxed form. In addition, APC increased the enzymatic (catalase) and nonenzymatic (GSH) antioxidant components of murine macrophages. Taken together, APC exhibited an antioxidant activity which was mediated both via decreased generation of free radicals along with increase in cellular antioxidants.

In vitro anti inflammatory activity of Aloe vera by down regulation of MMP-9 in peripheral blood mononuclear cells

AIM OF THE STUDY

The anti-inflammatory activity of Aloe vera was investigated through MMP inhibition studies. The effect of Aloe vera on MMP-9 inhibition was tested on peripheral blood mononuclear cells (PBMC).

MATERIALS AND METHODS

Peripheral blood mononuclear cells (PBMC) were isolated from the heparinised venous blood by Ficoll Diatrizoate gradient centrifugation. The cell count and viability was determined using dye exclusion technique. Cytotoxicity was evaluated by MTT assay. Activation of MMP-9 was visualized by gelatin zymography. Inhibition of MMP-9 in the presence of aqueous extract of Aloe vera was detected by gelatin zymography and confirmed by RT-PCR.

RESULTS

Peripheral blood mononuclear cells (PBMC) showed significant inhibition in the activity of MMP-9, indicating the in vitro inhibitory effect of Aloe vera on MMP-9. Zymographic analysis and RT-PCR showed that it caused a significant reduction in the production of MMP-9 in a concentration dependent manner.

CONCLUSION

The inhibition of MMP-9 production in the cells was detected by gelatin zymography and was confirmed by RT-PCR.

Aloe vera extract activity on human corneal cells

CONTEXT

Ocular diseases are currently an important problem in modern societies. Patients suffer from various ophthalmologic ailments namely, conjunctivitis, dry eye, dacryocystitis or degenerative diseases. Therefore, there is a need to introduce new treatment methods, including medicinal plants usage. Aloe vera [Aloe barbadensis Miller (Liliaceae)] possesses wound-healing properties and shows immunomodulatory, anti-inflammatory or antioxidant activities.

MATERIALS AND METHODS

NR uptake, MTT, DPPH• reduction, Griess reaction, ELISA and rhodamine-phalloidin staining were used to test toxicity, antiproliferative activity, reactive oxygen species (ROS) reduction, nitric oxide (NO) and cytokine level, and distribution of F-actin in cells, respectively.

AIM

The present study analyzes the effect of Aloe vera extracts obtained with different solvents on in vitro culture of human 10.014 pRSV-T corneal cells.

RESULTS

We found no toxicity of ethanol, ethyl acetate and heptane extracts of Aloe vera on human corneal cells. No ROS reducing activity by heptane extract and trace action by ethanol (only at high concentration 125 µg/ml) extract of Aloe vera was observed. Only ethyl acetate extract expressed distinct free radical scavenging effect. Plant extracts decreased NO production by human corneal cells as compared to untreated controls. The cytokine (IL-1β, IL-6, TNF-α and IL-10) production decreased after the addition of Aloe vera extracts to the culture media.

DISCUSSION AND CONCLUSIONS

Aloe vera contains multiple pharmacologically active substances which are capable of modulating cellular phenotypes and functions. Aloe vera ethanol and ethyl acetate extracts may be used in eye drops to treat inflammations and other ailments of external parts of the eye such as the cornea.

Anti-inflammatory effect of a methanolic extract of leaves of Dregea volubilis

AIM OF STUDY

The aim of this study was to establish the anti-inflammatory activity of the methanolic extract of Dregea volubilis leaves (MEDV) with its fractions and to delineate the possible mechanism of action for MEDV.

MATERIALS AND METHODS

The anti-inflammatory activities of MEDV along with its petroleum ether and chloroform fractions were evaluated in a carrageenan induced model of acute inflammation. The effect of MEDV on lipopolysaccharide induced production of nitric oxide (NO) in macrophages was also studied.

RESULTS

MEDV (100, 200 and 400 mg/kg body weight) significantly reduced carrageenan induced paw edema; chloroform fraction was most potent (66%, p<0.001). MEDV was non-toxic up to 125 μg/ml in mouse peritoneal macrophages wherein it (0-100 μg/ml) reduced lipopolysaccharide induced NO production.

CONCLUSION

MEDV possesses significant anti-inflammatory activity. Chloroform fraction of MEDV showed best anti-inflammatory activity.

An ethanol extract of Piper betle Linn. mediates its anti-inflammatory activity via down-regulation of nitric oxide

The leaves of Piper betle (locally known as Paan) have long been in use in the Indian indigenous system of medicine for the relief of pain; however, the underlying molecular mechanisms of this effect have not been elucidated. The anti-inflammatory and immunomodulatory effects of an ethanolic extract of the leaves of P. betle (100 mg kg−1; PB) were demonstrated in a complete Freund's adjuvant-induced model of arthritis in rats with dexamethasone (0.1 mg kg−1) as the positive control. At non-toxic concentrations of PB (5–25 μg mL−1), a dose-dependent decrease in extracellular production of nitric oxide in murine peritoneal macrophages was measured by the Griess assay and corroborated by flow cytometry using the nitric oxide specific probe, 4,5-diaminofluorescein-2 diacetate. This decreased generation of reactive nitrogen species was mediated by PB progressively down-regulating transcription of inducible nitric oxide synthase in macrophages, and concomitantly causing a dose-dependent decrease in the expression of interleukin-12 p40, indicating the ability of PB to down-regulate T-helper 1 pro-inflammatory responses. Taken together, the anti-inflammatory and anti-arthrotic activity of PB is attributable to its ability to down-regulate the generation of reactive nitrogen species, thus meriting further pharmacological investigation.