Health and commercial relevance of Garcinia species: Key scientometric analyses from three decades of research

Garcinia species (G. indica, G. cambogia, G. kola and G. mangostana) represent some of the most sought-after herbs globally due to their impressive medicinal qualities, hence the ever-growing interest of researchers into these plants. In this study, an extensive bibliometric analysis of the available research outputs on the widely-known Garcinia species was conducted to appraise the progress made and also highlight the future focus of research on the plants. The published articles (original and conference articles) on the selected species from 1991 to 2021 were retrieved from Scopus® database, scrutinized and further analyzed using the VOS viewer software. Over 2000 research outputs were published posting an annual publication rate of 75 articles, which have altogether garnered almost 37000 citations within the period under review. Of the 85 country affiliations on the publications, 5, which include India, Thailand, Nigeria, Indonesia, and the United States have cumulatively contributed two-thirds of the total outputs. The institutions; the University of Ibadan (97), Prince Songkla University (52) and Mahidol University (50) have the most publications revealing their research focus on herbs. However, in terms of individual influence, Prof E.O. Farombi, of the University of Ibadan, led the pack with an impressive 42 publications (1585 citations) on Garcinia kola followed by Prof Y.W. Chin of the Seoul National University, South Korea with 23 publications (452 citations) on Garcinia mangostana. The versatility in the health applications of these species especially as sources for new therapeutics, nutraceuticals or functional food ingredients, has been the main driver of the research within the past three decades. Recent research undertakings have demonstrated the potential industrial uses of herbs in the clothing and petroleum industries and these may dominate the research emphases in the immediate future

Antidiabetic properties of centella asiatica in type II diabetic rats.

Doctor of Philosophy in Biochemistry. University of KwaZulu-Natal, Durban 2016.Abstract available in PDF file

Antioxidant -Rich Natural Products and Diabetes Mellitus

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Potential Antioxidative Effects of Kolaviron on Reproductive Function in Streptozotocin-Induced Diabetic Wistar Rats

The present study investigated the effects of Kolaviron (KV) on the testicular and epididymal tissue antioxidant status in streptozotocin (STZ)-induced diabetic rats. Diabetes was induced by a single intraperitoneal injection of STZ at 50 mg/kg body weight. The antioxidant status was studied by evaluating epididymal and testicular levels of malondialdehyde (MDA), a lipid peroxidation (LPO) marker, and the activities of catalase (CAT) glutathione peroxidase (GPX) and superoxide dismutase (SOD) were also assessed using biochemical techniques. Diabetes induction resulted in testicular and epididymal LPO and adversely affected the activities of antioxidant enzymes evident by a noticeable decrease in enzyme activity in both tissues. The potential antioxidative effects of KV in the testicular and epididymal tissues of STZ-induced diabetes were revealed by its ability to mitigate against LPO and increase the activity of antioxidant defense enzymes in the reproductive tissues studied. KV might potentially be used as an antioxidant as well as antidiabetic treatment; however, further studies are needed

Antioxidant-Rich Vegetables: Impact on Human Health

Antioxidants are valuable ingredients present in vegetables. Vegetables are essential and crucial in human’s health and diet because of their minerals, antioxidant vitamins, phytochemical compounds, and dietary fibre content. This is the reason why an adequate consumption of vegetables has been linked with reduced risk and protection against various chronic diseases. Notably, each vegetable belongs to a group that contains a unique quantity of phytochemical compounds, which distinguish them from other groups and even within their group. The exact mechanisms by which the consumption of vegetables protects against human diseases are yet to be fully understood. However, the phytochemicals present in vegetables could be responsible for attenuating some of them. These phytochemicals are strong antioxidants that reduce the risk of chronic diseases by mounting resistance against the generation of free radicals and their damage. They are also involved in the modification of metabolic activation, detoxification of carcinogenic compounds, or attack of tumour formation in cells. This review highlights the inherent antioxidant potentials of vegetables, their roles as an excellent source of antioxidants and their impact on human health and diseases. Information provided in this review will provide more insight into the roles of antioxidants present in vegetables

Selective cytotoxic and anti-metastatic activity in DU-145 prostate cancer cells induced by 'Annona muricata' L. bark extract and phytochemical, annonacin

Background: Annona muricata L. was identified as a popular medicinal plant in treatment regimens among cancer patients in Jamaica by a previously conducted structured questionnaire. Ethnomedically used plant parts, were examined in this study against human prostate cancer cells for the first time and mechanisms of action elucidated for the most potent of them, along with the active phytochemical, annonacin. Methods: Nine extracts of varying polarity from the leaves and bark of A. muricata were assessed initially for cytotoxicity using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on PC-3 prostate cancer cells and the ethyl acetate bark (EAB) extract was identified as the most potent. EAB extract was then standardized for annonacin content using High-performance Liquid Chromatography - Mass Spectrometry (HPLC-MS) and shown to be effective against a second prostate cancer cell line (DU-145) also. The mode of cell death in DU-145 cells were assessed via several apoptotic assays including induction of increased reactive oxygen species (ROS) production, reduction of mitochondrial membrane potential, activation of caspases and annexin V externalization combined with morphological observations using confocal microscopy. In addition, the potential to prevent metastasis was examined via inhibition of cell migration, vascular endothelial growth factor (VEGF) and angiogenesis using the chorioallantoic membrane assay (CAM). Results: Annonacin and EAB extract displayed selective and potent cytotoxicity against the DU-145 prostate carcinoma cells with IC50 values of 0.1 ± 0.07 μM and 55.501 ± 0.55 μg/mL respectively, without impacting RWPE-1 normal prostate cells, in stark contrast to chemotherapeutic docetaxel which lacked such selectivity. Docetaxel’s impact on the cancerous DU-145 was improved by 50% when used in combination with EAB extract. Insignificant levels of intracellular ROS content, depolarization of mitochondrial membrane, Caspase 3/7 activation, annexin V content, along with stained morphological evaluations, pointed to a non-apoptotic mode of cell death. The extract at 50 μg/mL deterred cell migration in the wound-healing assay, while inhibition of angiogenesis was displayed in the CAM and VEGF inhibition assays for both EAB (100 μg /mL) and annonacin (0.5 μM). Conclusions: Taken together, the standardized EAB extract and annonacin appear to induce selective and potent cell death via a necrotic pathway in DU-145 cells, while also preventing cell migration and angiogenesis, which warrant further examinations for mechanistic insights and validity in-vivo

Hepato- and neuro-protective effects of watermelon juice on acute ethanol-induced oxidative stress in rats

Chronic and acute alcohol exposure has been extensively reported to cause oxidative stress in hepatic and extra-hepatic tissues. Watermelon (Citrullus lanatus ) is known to possess various beneficial properties including, antioxidant, anti-inflammatory, analgesic, anti-diabetic, anti-ulcerogenic effects. However, there is a lack of pertinent information on its importance in acute alcohol-induced hepato- and neuro-toxicity. The present study evaluated the potential protective effects of watermelon juice on ethanol-induced oxidative stress in the liver and brain of male Wistar rats. Rats were pre-treated with the watermelon juice at a dose of 4 ml/kg body weight for a period of fifteen days prior to a single dose of ethanol (50%, 12 ml/kg body weight). Ethanol treatment reduced body weight gain and significantly altered antioxidant status in the liver and brain. This is evidenced by the significant elevation of malondialdehyde (MDA) concentration, depletion in reduced glutathione (GSH) levels and an increased catalase (CAT) activity in the brain and liver. There was no significant difference in the activity of glutathione peroxidase (GPX) in the liver and brain. Oral administration of watermelon juice for fifteen (15) days prior to ethanol intoxication, significantly reduced the concentration of MDA in the liver and brain of rats. In addition, water melon pre-treatment increased the concentration of GSH and normalized catalase activity in both tissues in comparison to the ethanol control group. Phytochemical analysis revealed the presence of phenol, alkaloids, saponins, tannins and steroids in watermelon juice. Our findings indicate that watermelon juice demonstrate anti-oxidative effects in ethanol-induced oxidation in the liver and brain of rats, which could be associated with the plethora of antioxidant phyto-constituents present there-in

Antidiabetic effects of resveratrol: the way forward in Its clinical utility

Despite recent advances in the understanding and management of diabetes mellitus, the prevalence of the disease is increasing unabatedly with resulting disabling and life-reducing consequences to the global human population. The limitations and side effects associated with current antidiabetic therapies have necessitated the search for novel therapeutic agents. Due to the multipathogenicity of diabetes mellitus, plant-derived compounds with proven multiple pharmacological actions have been postulated to “hold the key” in the search for an affordable, efficacious, and safer therapeutic agent in the treatment of the disease and associated complications. Resveratrol, a phytoalexin present in few plant species, has demonstrated beneficial antidiabetic effects in animals and humans through diverse mechanisms and multiple molecular targets. However, despite the enthusiasm and widespread successes achieved with the use of resveratrol in animal models of diabetes mellitus, there are extremely limited clinical data to confirm the antidiabetic qualities of resveratrol. This review presents an update on the mechanisms of action and protection of resveratrol in diabetes mellitus, highlights challenges in its clinical utility, and suggests the way forward in translating the promising preclinical data to a possible antidiabetic drug in the near future