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How African star apple boosts brain functions, memory

By Chukwuma Muanya
03 February 2022   |   4:02 am
Scientists have for the first time demonstrated how African star apple fruit-supplemented diet could be used to enhance cognitive functions and attenuates lipopolysaccharide-induced memory impairment....

African cherry Credit: Healthfacts.ng

• Consumption of fruit pulp in pregnancy as intermittent preventive therapy against malaria

Scientists have for the first time demonstrated how African star apple fruit-supplemented diet could be used to enhance cognitive functions and attenuates lipopolysaccharide-induced memory impairment, oxidative stress, and release of proinflammatory cytokines as well as prevent malaria in pregnancy.

The study was published in the journal Nutrire. According to the researchers, fruit-based supplement has an important role in protecting the brain against oxido-inflammatory stress. Chrysophyllum albidum (African star apple) fruit contained several phytonutrients that possess antioxidants and anti-inflammatory properties. Hence, this study investigated the effect of C. albidum fruit supplemented diet (CAFD) on cognitive functions and lipopolysaccharide (LPS)-induced memory impairment and oxido-inflammatory response in mice.

Mice were randomised into two experiments. Experiment 1 with naïve mice contained four groups (n = 6) while experiment 2 with LPS contains five groups (n = 6). Mice in experiments 1 and 2 were fed on CAFD (5%, 10%, and 20%) in naïve (6 weeks) and LPS (250 μg/kg, i.p.) in the 7th week, respectively. Cognitive performance was tested using Y-maze test (YMT) and novel object recognition test (NORT) in the naïve and LPS mice. Brain samples were obtained for determination of oxido-inflammatory parameters and acetylcholinesterase activity.

According to the results, the CAFD significantly enhanced cognitive performance in the YMT and NORT in naïve and LPS mice, as evidenced by increased % alternation and discrimination index, respectively. CAFD supplementation significantly reduced acetylcholinesterase enzyme activity while it attenuated depletion of reduced glutathione and catalase activities in brains of naive and LPS-treated animals. The CAFD significantly reduced LPS-induced increased malondialdehyde levels in mice brains. CAFD supplementation significantly attenuated LPS-induced pro-inflammatory cytokines (IL-6, TNF-α) in mice brains.

The researchers concluded: “Chrysophyllum albidum fruit supplementation in diet enhances memory function and prevents cognitive deficits induced by LPS via mechanisms associated with inhibition of oxidative stress-related processes, acetylcholinesterase activity, and pro-inflammatory mediators.”

Indeed, the high prevalence of micronutrient deficiencies in developing countries has been attributed to the inadequacy in knowledge of the nutritional value of fruits and vegetables, as well as their low consumption, despite their availability in these countries. The health-benefiting and health-promoting properties of fruits are due to their richness in micronutrients and phytochemicals required for the growth, development, and optimal functioning of the human body. As part of a healthy diet low in fat, sugars, and sodium, the World Health Organization (WHO) suggests consuming more than 400 g of fruits and vegetables per day. Frequent consumption of fruits and vegetables has been associated with lowered vulnerability risk factor for non-communicable diseases (NCDs) such as Alzheimer’s disease, Parkinson’s disease, depression, autoimmune diseases, diabetes, coronary heart disease, cancer, stroke, osteoarthritis, osteoporosis, and others and possibly delayed onset of age-related disorders.

Recent findings showed that NCDs are the leading cause of death globally. Expanded body of epidemiological studies have shown that NCDs kill approximately 41 million people each year, accounting for about 85% of all premature deaths globally. The 2030 Agenda for Sustainable Development recognises NCDs as a major challenge for sustainable development particularly in developing countries.

Indeed, several epidemiological reports have shown the involvement of systemic bacterial, parasitic, or viral infections including influenza, Toxoplasma gondii, and COVID-19 in the vulnerability and pathogenesis of some neurodegenerative diseases in developing countries. Emerging evidence shows that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pathogenic agent for coronavirus disease 2019 (COVID-19), is a neuroinvasive virus capable of causing neurodegeneration and neuropsychiatric disease via cytokine storm. These evidences have led to the design of animal models involving exposures to infectious compounds to mimic certain features of some neurodegenerative disease.

Accordingly, lipololysaccharide (LPS) is a widely used endotoxin of gram-negative bacteria popularly used to simulate behavioral and neuroinflammation and oxidative biochemical changes that characterized neurodegenerative pathology including conditions of cognitive dysfunction. Neuroinflammation and oxidative stress has distinct features that are shared in ageing and in neurodegenerative diseases such as stroke and Alzheimer’s disease (AD). The activation of the immune system in response to an infectious or bacterial endotoxin, LPS produces profound neurophysiological, neuroendocrine, and behavioral changes. Therefore, the injection of LPS promotes the production and release of several cytokines. In response to these cytokines, several reactive oxygen species are produced from cells such as neutrophils and other phagocytic cells, creating a status of vicious oxidative stress.

Although acute neuroinflammation plays a protective role, chronic neuroinflammation is frequently considered detrimental and damaging to nervous tissues. LPS-induced neuroinflammation has been repeatedly linked to microglia stress and modulation of broad spectrum of cellular responses partly due to repeated exposure to infectious agents. Thus, LPS serves as neuroinflammatory tool for the screening of compounds with neuroprotective property.

Considering the fact that the global incidence of non-communicable neurological disorders are increasing at an alarming rate, there is a global move toward the development of cost-effective natural neuroprotective phytochemicals. As part of this agenda, research institutions and Government policy on health are committed to develop ambitious national responses, by 2030, to reduce by one-third premature mortality from NCDs through prevention and treatment, which include dietary modification. Indeed, a nutritional approach could be a potential strategy to prevent or slow the progression of some NCDs especially neurodegenerative diseases, as experimental and clinical studies have reported significant decrease in risk factor for neurological NCDs and phytochemical supplementations. Phytochemicals are required for the maintenance of cell viability and protection of neural cells from neuroinflammation and oxidative stress associated with aging and brain diseases. Although the mechanisms of nutritional impact on the brain are complex, fruits and its juice impart beneficial effect on brain functioning.

In recent years, various groups of researchers have performed food-based intervention studies to reveal the effect of dietary factors on certain mechanisms that take care of mental activity and the potential of phytochemical-rich foods to prevent age-related neurodegeneration and cognitive decline. In particular, evidence suggests that foods rich in flavonoids possess the greatest potential to act on cognitive processes; notably, via selective modulation of protein kinase and lipid kinase signaling cascades, which regulate transcription factors and gene expression involved in both synaptic plasticity and cerebrovascular blood flow.

Indeed, increased hippocampalneurogenesis by diet has been linked repeatedly to improved cognition performance, brain plasticity, and mental health. Also, there has been expanding body of evidence showing strong connections between poor dieting, cellular aging, and cognitive impairment failure.

Chrysophyllum albidum, also known as African star apple, belongs to the family Sapotaceae. It is primarily a forest tree species with its natural occurrences in diverse ecozones in Nigeria, Uganda, and Niger Republic. In Nigeria, C. albidum is known as “agbalumo” in South Western Nigeria and “udara” in South Eastern Nigeria. The fruit is seasonal with immense economic potential, especially following the report that jams obtained from the fruit-pulp could compete with raspberry jams and jellies, while the oil from the seed has been used for diverse medicinal purposes. Its rich sources of natural antioxidants have been established to promote health by acting against oxidative stress-related diseases such as diabetes, cancer, and coronary heart diseases. The fruit-pulp has been reported to contain significant amount of ascorbic acid, vitamins, iron, food flavours, fat, carbohydrate and mineral elements. The fruit-peel has been shown to be a rich source of fiber and mineral while the seed shell pericarp has been reported to be good source of carbohydrate and minerals. The fruits are not only consumed fresh but also used to produce stewed fruit, marmalade, syrup, and several types of soft drinks. Its high pectin content is also suggestive of its vast medicinal benefits, which includes plasma cholesterol level reduction, as well as its detoxifying action and effectiveness in diarrhea therapy. However, there is a significant gap in knowledge of the neuroprotective property of C. albidum in disease conditions related to oxidative stress and neuroinflammation in experimental animals.

The researchers said as part of their ongoing studies of the neuropharmacological activity of C. albidum, they therefore hypothesised that (i) supplementation of C. albidum fruit supplemented diet (CAFD) would improve memory performance in naïve and LPS-treated mice, (ii) prolonged CAFD supplementation could prevent oxidative and nitrergic alterations in naïve and LPS-treated mice, and (iii) repeated CAFD supplementation would attenuate pro-inflammatory proteins release in naïve and LPS-exposed mice.

The researchers are from the Neuropharmacology Unit, Department of Pharmacology and Therapeutics, Faculty of Basic Medical Sciences, University of Ibadan, Ibadan, Oyo State, and
Department of Pharmacology, Faculty of Basic Medical Sciences, PAMO University of Medical Sciences, Port Harcourt, Rivers State, Nigeria.

Also, Nigeria scientists have demonstrated that traditional consumption of the fruit pulp of African cherry (Chrysophyllum albidum) in pregnancy may be serving as an intermittent preventive therapy against malaria infection.

The study was published in the journal Ancient Science of Life by researchers from Nnamdi Azikiwe University, Awka, Anambra State.

The researchers wrote: “The bark of Chrysophyllum albidum is reported to possess antimalarial property. The fruit pulp of C. albidum consumed by pregnant women of south eastern Nigeria may also possess antimalarial activity. The present preliminary study investigated the antimalarial potential of the pulp juice and seed of C. albidum.

“Schizonticidal activity was evaluated using the Peter’s four-day suppressive test. The prophylactic and curative antimalarial activities of the extracts were evaluated in Albino mice inoculated with Plasmodium berghei. The oral acute toxic dose of the pulp extract is beyond 5000 mg/kg. The seed and pulp possess both suppressive and curative properties. The seed extract suppressed early infection by 72.97% and 97.30%, at 500 and 1000 mg/kg, respectively. The pulp juice recorded 72.97% and 81.08%, at 500 and 1000 mg/kg, respectively. At 500 mg/kg dose, the level of parasite control on Day 7 was the same (96.10%) for both seed and pulp.”

The researchers concluded: “This study demonstrates the presence of antimalarial constituents in the chemically uncharacterized samples (fruit pulp and seed) of C. albidum. Its ethnomedicinal use may be valuable in pregnancy where it may possibly serve as an intermittent preventive therapy against malaria.”

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