Researchers at the University of Campinas’s Biology Institute (IB-UNICAMP) in São Paulo State, Brazil, have discovered that jaboticaba peel extract can prevent prediabetes and fatty liver (hepatic steatosis) in mice.
The species of jaboticaba used in the study was Myrciaria jaboticaba, also known as the Brazilian grape tree.
“We found that when jaboticaba peel extract was given to older mice fed a high-fat diet, it reduced weight gain, dyslipidemia [abnormally elevated levels of fat in the blood] and hyperglycemia [high blood sugar], and it boosted the levels of HDL [good cholesterol], among other benefits,” Valéria Helena Alves Cagnon Quitete, a professor at IB-UNICAMP and principal investigator for the project, told Agência FAPESP.
The extract was developed in partnership with researchers at the same university’s Food Engineering School (FEA-UNICAMP), led by Professor Mário Roberto Maróstica Junior. The latter had previously studied the effects of adding jaboticaba peel to animal feed.
The extract they produced can be administered in a controlled manner and contains a large proportion of bioactive compounds – substances that occur naturally in foods and interfere positively in metabolism but are not nutritionally necessary. It has been patented and is currently in the process of being licensed by a Brazilian company.
“We succeeded in developing a method to obtain a large amount of bioactive compounds from jaboticaba peel in a small amount of extract,” said Celina de Almeida Lamas, a doctoral researcher at IB-UNICAMP and a coauthor of the study.
Chemical analysis of jaboticaba peel extract had already shown high levels of phenolic compounds, including anthocyanin, also present in red wine, with positive effects on the metabolism.
The researchers conducted an experiment with aging mice to determine the optimal dose of the extract in therapeutic strategies designed to bring about the desired benefits and to find out whether a high dose would amplify its effect.
Aging is directly associated with a reduction in metabolic capacity and with metabolic alterations in the liver, blood sugar and lipid processing. Control of blood sugar levels becomes impaired during the aging process, triglyceride deposition in the liver increases, and hormone imbalance is frequent. These alterations are associated with dyslipidemia, hyperinsulinemia, diabetes and cardiovascular disease, which are common disorders in older people.
To boost these harmful effects of aging in mice, the researchers fed them a high-fat diet designed to lead to weight gain, increase liver fat, stimulate dyslipidemia and raise blood sugar levels. The high-fat diet had five times the amount of lipids in a normal diet.
“Previous research showed that consumption of this high-fat diet for 60 days would be sufficient for the animals to develop prediabetes and alterations to the metabolism of the liver. We decided to feed them the extract for this same period to see whether the same problems were present at the end of two months,” Lamas explained.
The mice were divided into seven groups, one of which consisted of young animals aged 3 months and fed a standard diet for 60 days. The second and third groups consisted of 11-month-old mice, which were fed a standard or high-fat diet.
The fourth and fifth groups consisted of older mice, which were fed different doses of the extract by gavage (via a PVC tube leading down the throat to the stomach) together with a standard diet. The extract was fed at doses of 2.9 grams and 5.8 grams per kilo of body weight, respectively.
The sixth and seventh groups also consisted of older mice, which received the same doses of the extract but with a high-fat diet.
The analysis showed that in the older mice, both doses of the jaboticaba peel extract prevented weight gain, mitigated the inflammatory process and reduced hyperglycemia and dyslipidemia, averting prediabetes.
In addition, the extract raised HDL levels and boosted the activity of receptors associated with insulin and of certain molecules linked to the proliferation of peroxisomes – cytoplasmic organelles containing enzymes that oxidize fatty acids.
“We found that the extract improved liver morphology in the animals,” Quitete said.
The researchers also found that the higher dose of jaboticaba peel extract – 5.8 g/kg – was more effective in promoting these beneficial effects than the lower dose.
“The double dose had a better effect on important metabolic pathways linked to obesity, prediabetes and restoration of the liver’s structure in the older mice,” Quitete said.
The group is currently conducting a study to evaluate the use of jaboticaba peel extract to delay prostate cancer progression in transgenic mice, also with FAPESP’s support. Preliminary results suggest that the extract reduced lesions in the prostate.
“We noted a substantial improvement in prostate morphology, as well as reduced oxidative stress and inflammation,” Quitete said.
“The reduction in inflammation and oxidative stress led to an improvement in prostate tissue and molecular structure.”