ABSTRACT
Psychotria densinervia hydro-ethanolic leaf extract (PHELE) and bark extract (PHEBE) were evaluated for antioxidant, anti-inflammatory, and inhibition of digestive enzymes activities. The antioxidant activity was characterized by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), total phenolic content (TPC), and total flavonoid content (TFC) assays. The anti-inflammatory activity was characterized by protein denaturation and antiproteinase tests, while the inhibition of the enzymes was assessed using α-amylase, α-glucosidase, lipase, and cholesterol esterase activities. PHELE presented low (p < 0.001) IC50 (59.09 ± 5.97 µg/ml) for DPPH compared with ascorbic acid (71.78 ± 6.37 µg/ml) and PHEBE (115.40 ± 1.21 µg/ml). The IC50 of PHELE (262.4 ± 4.46 µg/ml) and PHEBE (354.2 ± 1.97 µg/ml) was higher (p < 0.001) than that of catechin (33.48 ± 2.02 µg/ml) for ABTS. PHELE had high (p < 0.001) FRAP (341.73 ± 21.70 mg CE/g) than PHEBE (150.30 ± 0.32 mg CE/g). PHELE presented (p < 0.001) high TPC (270.05 ± 7.53 mg CE/g) and TFC (23.43 ± 0.032 mg CE/g) than PHEBE (TPC: 138.89 ± 0.91 and TFC: 20.06 ± 0.032 mg CE/g). PHELE showed antiprotein denaturation with IC50 (257.0 ± 7.51 µg/ml) (p < 0.001) and antiproteinase activity (74.37 ± 1.10 µg/ml) lower than PHEBE (316.1 ± 6.02 µg/ml and 177.6 ± 0.50 µg/ml), respectively. Orlistat inhibited lipase (p < 0.001) activity with IC50 (37.11 ± 4.39 µg/ml) lower than PHELE and PHEBE (50.57 ± 2.89 µg/ml and 62.88 ± 1.74 µg/ml, respectively). PHELE inhibited cholesterol esterase with IC50 (34.75 ± 3.87 µg/ml) lower than orlistat (54.61 ± 2.56) and PHEBE (80.14 ± 1.71 µg/ml). PHELE inhibited α-amylase IC50 (6.07 ± 4.05 µg/ml) lower than PHEBE (19.69 ± 6.27 µg/ml) and acarbose (20.01 ± 2.84 µg/ml). Acarbose inhibited α-glucosidase (p < 0.001) activity with IC50 (4.11 ± 3.47 µg/ml) lower than PHELE (24.41 ± 2.84 µg/ml) and PHEBE (38.81 ± 2.46 µg/ml). PHELE presented better antioxidant, anti-inflammatory, and enzyme inhibition activity than PHEBE.
ABSTRACT
BACKGROUND: Cafeteria diet is known to induce excessive body fat accumulation (obesity) that could cause metabolic and cardiovascular changes and even death. The increase in prevalence over time and the failure in treatment options make obesity a real public health problem. The present study assessed the preventive effect of the hydro-ethanolic extract of the Piper nigrum leaf on the development of metabolic and cardiovascular changes in cafeteria diet fed Wistar rats. METHODS: Thirty-six male rats were divided into 5 groups of 6 rats each: a normal control group (Nor.), a negative control group (Neg.), two groups administered different doses of extract in mg/kg (E250 and E500), and a group administered atorvastatin 10 mg/kg (Ator., reference drug). The animals were fed with experimental diets (standard and cafeteria) for a period of 5 weeks. Food and water intake were assessed daily, and the body weight assessed weekly. At the end of the feeding, plasma lipid profile and markers of hepatic and renal function were assessed. Furthermore, the relative weights of the adipose tissue and the organs were assessed. The liver, kidneys, and heart homogenates were assessed for markers of oxidative stress while the aorta was histopathologically examined. RESULTS: Cafeteria diet-induced weight gain of 30% and increased triglyceride, total cholesterol, and low-density lipoprotein cholesterol level of more than 50%. Equally, an increase in the relative weight of accumulated adipose tissues of more than 90%, oxidative stress, and alteration in the organ structure were visible in cafeteria diet fed rats (Neg). Treatment with P. nigrum extract significantly prevented weight gain, dyslipidemia, oxidative stress, and alteration in the architecture of the aorta. The effect of P. nigrum extract was comparable to that of the reference drug. CONCLUSION: Piper nigrum leaf may prevent weight gain and possess cardioprotective activity with a strong antioxidant activity.
