Ursolic acid attenuates beta-amyloid-induced memory impairment in mice / Ácido ursólico atenua a perda de memória induzida por beta-amilóide em ratos

ABSTRACT Objective Increasing evidence demonstrates that oxidative stress and inflammatory are involved in amyloid β (Aβ)-induced memory impairments. Ursolic acid (UA), a triterpenoid compound, has potent anti-inflammatory and antioxidant activities. However, it remains unclear whether UA attenuates Aβ-induced neurotoxicity. Method The aggregated Aβ25-35 was intracerebroventricularly administered to mice. Results We found that UA significantly reversed the Aβ25-35-induced learning and memory deficits. Our results indicated that one of the potential mechanisms of the neuroprotective effect was attenuating the Aβ25-35-induced accumulation of malondialdehyde (MDA) and depletion of glutathione (GSH) in the hippocampus. Furthermore, UA significantly suppressed the upregulation of IL-1β, IL-6, and tumor necrosis-α factor levels in the hippocampus of Aβ25-35-treated mice. Conclusion These findings suggest that UA prevents memory impairment through amelioration of oxidative stress, inflammatory response and may offer a novel therapeutic strategy for the treatment of Alzheimer’s disease.

RESUMO Objetivo Há evidências crescentes de que o estresse oxidativo e a inflamação estão envolvidos na perda de memória induzida pelo peptídeo beta-amilóide (βA). O ácido ursólico (AU), um composto triterpenóide, apresenta atividades anti-inflamatórias e antioxidantes potentes. Entretanto, não se sabe ainda se o AU atenua a neurotoxicidade induzida pelo βA. Método O agregado βA 25-35 foi administrado aos ratos por via intracerebroventricular. Resultados Observou-se que o AU reverteu significativamente os déficits de aprendizado e de memória induzidos pelo βA 25-35. Portanto, um dos potenciais mecanismos do efeito neuroprotetor seria a atenuação do acúmulo de malondialdeído e a depleção de glutationa no hipocampo induzidos pelo βA 25-35. Além disso, o AU suprimiu significativamente a supra regulação dos níveis de IL-1β, IL-6 e do fator de necrose tumoral α no hipocampo dos ratos tratados com βA 25-35. Conclusão Esses achados sugerem que o AU previne a perda de memória através da melhora do estresse oxidativo e da resposta inflamatória, podendoproporcionar uma nova estratégia terapêutica para o tratamento da doença de Alzheimer.

Antidiabetic activity of a triterpenoid saponin isolated from Momordica cymbalaria Fenzl.

Glucose uptake by isolated diaphragms of both diabetic, following streptozotocin administration, and non-diabetic animals increased in presence of an oleanane-type triterpenoid saponin isolated from the roots of M. cymbalaria. Insulin release was augmented by the presence of the saponin of M. cymbalaria (1 mg/mL) in rat insulinoma cell line (RIN-5F) pre-exposed to adrenaline (5 µM) and nifedipine (50 µM). Pancreatic histology also indicated considerable quantitative increase in β-cells (75%) when treated with the saponin. The results suggest that the saponin of M. cymbalaria possesses potential antidiabetic activity with respect to insulin secretion, which may be attributed to modulation of calcium channel, and β-cell rejuvenation.

Anti-diabetic effect of a combination of andrographolide-enriched extract of Andrographis paniculata (Burm f.) Nees and asiaticoside-enriched extract of Centella asiatica L. in high fructose-fat fed rats.

Traditionally, a combination of medicinal plants is commonly used for lowering blood glucose in diabetic patients in order to provide additional benefits of the single drug. A. paniculata and C. asiatica are two traditional medicines form South Asian and Southeast Asain countries consumed by people for treating daibates mellitus and its complications. Hyperglycemia in the rats was stimulated by high fructose-fat diet that consists of 36% fructose, 15% lard, and 5% egg yolks in 0.36 g/200 g body weight for 70 days. The rats were orally administered with the combination of andrographolide-enriched extract of A. paniculata (AEEAP) leaves and asiaticoside-enriched extract of C. asiatica (AEECA) herbs from day 70 for 7 days. Antidiabetic activity was evaluated by estimating mainly the blood glucose levels and other parameters such as HDL, LDL, cholesterol and triglyceride. The results showed that combination at the ratio of 70:30 exhibited a promosing antidiabetic effect in high-fat-fructose-fed rat, and exhibited sinergistic effects on blood cholesterol and HDL levels. It can be concluded that its antidiabetic effect was better than that of single treatment of AEEAP or AEECA. That combination was also potential to develop as a blood glucose-lowering agent for diabetic patients.

Lupeol, a triterpene, prevents free radical mediated macromolecular damage and alleviates benzoyl peroxide induced biochemical alterations in murine skin.

In our earlier communication we have shown that Lupeol inhibits early responses of tumour induction in murine skin. The free radical mediated damage to the cellular macromolecules such as DNA, proteins, lipids and alteration in the activities of quinone reductase and xanthine oxidase are important biochemical parameters of tumor development. The suppression of free radical mediated damage to cellular macromolecules and induction of quinone reductase along with depletion of xanthine oxidase are prominent characteristics of chemopreventive agents. In the present investigation, we have elucidated the mechanism of action of lupeol (Lup-20 (29)-en-3beta-ol), a triterpene found in moderate amount in many vegetables, fruits and anti-tumor herbs. In the present investigation, lupeol significantly reduced the free radical mediated DNA-sugar damage and microsomal lipid peroxidation in an iron/ascorbate free radical generating system in vitro. Benzoyl peroxide, a known free radical generating tumor promoter mediated oxidation of proteins and modulation in the activities of quinone reductase as well as xanthine oxidase was significantly prevented by lupeol when tested on murine skin in vivo. It was concluded from this study that lupeol acts as an effective chemopreventive agent against cutaneous toxicity.

Glycoside-bearing liposomal delivery systems against macrophage-associated disorders involving Mycobacterium leprae and Mycobacterium tuberculosis.

Asiaticoside, a plant glycoside with rhamnose as end sugar and having microbicidal properties was tested against Mycobacterium leprae and Mycobacterium tuberculosis both in vivo and in vitro. As rhamnose is reported to have no tissue specificity, corchorusin D having glucose as end sugar was used for targeting with an equimolar proportion of asiaticoside in liposomal form for testing the drug value. Results showed that liposomal asiaticoside had better microbicidal property against M. leprae and M. tuberculosis when compared to that of free asiaticoside whereas liposomes containing asiaticoside and corchorusin D were found to be equally or more active in comparison to liposomal asiaticoside alone. It is inferred that appropriate glycosides, if used in liposomal form (incorporated or covalently grafted) have enhanced drug efficacy and such glycoside bearing liposomes as targeted delivery systems could be used for chemotherapeutic control of several other diseases.