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Diabetic neuropathy is a risk factor for developing complications such as autonomic cardiovascular disease, osteoarthropathy, foot ulcers, and infections, which may be the direct cause of death. Even worse, patients plagued by this condition display painful neuropathic symptoms that are usually severe and frequently lead to depression, anxiety, and sleep disarrays, eventually leading to a poor quality of life. There is a general interest in evaluating the therapeutic properties of topical capsaicin cream as an effective agent for pain relief in these patients. As such, the current review makes use of major search engines like PubMed and Google Scholar, to bring an updated analysis of clinical studies reporting on the therapeutic effects of capsaicin in patients with painful diabetic neuropathy. In fact, most of the summarized literature indicates that topical capsaicin (0.075 %) cream, when applied to the painful areas for approximately 8 weeks, can reduce pain, which may lead to clinical improvements in walking, working, and sleeping in patients with painful diabetic neuropathy. The current review also discusses essential information on capsaicin, including its source, bioavailability profile, as well as treatment doses and duration, to highlight its therapeutic potential.

Obesity is a significant contributor to increased morbidity and premature mortality due to increasing the risk of many chronic metabolic diseases such as type 2 diabetes, cardiovascular disease and certain types of cancer. Lifestyle modifications such as energy restriction and increased physical activity are highly effective first-line treatment strategies used in the management of obesity. However, adherence to these behavioral changes is poor, with an increased reliance on synthetic drugs, which unfortunately are plagued by adverse effects. The identification of new and safer anti-obesity agents is thus of significant interest. In recent years, plants and their phenolic constituents have attracted increased attention due to their health-promoting properties. Amongst these, Cyclopia, an endemic South African plant commonly consumed as a herbal tea (honeybush), has been shown to possess modulating properties against oxidative stress, hyperglycemia, and obesity. Likewise, several studies have reported that some of the major phenolic compounds present in Cyclopia spp. exhibit anti-obesity effects, particularly by targeting adipose tissue. These phenolic compounds belong to the xanthone, flavonoid and benzophenone classes. The aim of this review is to assess the potential of Cyclopia extracts as an anti-obesity nutraceutical as underpinned by in vitro and in vivo studies and the underlying cellular mechanisms and biological pathways regulated by their phenolic compounds.

Metabolic complications in an obese state can be aggravated by an abnormal inflammatory response and enhanced production of reactive oxygen species. Pro-inflammatory response is known to be associated with the formation of toxic reactive oxygen species and subsequent generation of oxidative stress. Indeed, adipocytes from obese individuals display an altered adipokine profile, with upregulated expression and secretion of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin (IL-6). Interestingly, natural compounds, including phenolic enriched foods are increasingly explored for their ameliorative effects against various metabolic diseases. Of interest is gallic acid, a trihydroxybenzoic acid that has progressively demonstrated robust anti-obesity capabilities in various experimental models. In addition to reducing excessive lipid storage in obese subjects, gallic acid has been shown to specifically target the adipose tissue to suppress lipogenesis, improve insulin signaling, and concomitantly combat raised pro-inflammatory response and oxidative stress. This review will revise mechanisms involved in the pathophysiological effects of inflammation and oxidative stress in an obese state. To better inform on its therapeutic potential and improvement of human health, available evidence reporting on the anti-obesity properties of gallic acid and its derivatives will be discussed, with emphases on its modulatory effect on molecular mechanisms involved in insulin signaling, inflammation and oxidative stress.

Highlights • Depending on the concentration, dimethyl sulfoxide (DMSO) can be toxic to cells. • 3T3-L1 adipocytes are a well-established model to study anti-obesity properties. • DMSO doses ≥1% reduced cell viability and promoted cell damage in 3T3-L1 adipocytes., Dimethyl sulfoxide (DMSO) is an effective solvent and cytoprotectant agent that can induce diverse actions in experimental settings, ranging from metabolic stress to cytotoxic effects depending on the concentration used. Therefore, for the quality of experiments and reproducibility of results it is essential to establish a precise and non-toxic dose of DMSO within a specific cell system. 3T3-L1 adipocytes, represent a well-established in vitro cell model used to assess the anti-obesity potential of extracts and compounds. Although DMSO is commonly used as a solvent for these experiments, there is limited data available on the compounding effects of using DMSO. The purpose of this study was to assess a concentration-dependent effect of DMSO on lipid content, cell viability and oxidative damage in 3T3-L1 adipocytes. Results showed that DMSO at doses ≥ 0.1% increased mitochondrial membrane potential as measured by JC-1 fluorescent staining, while doses ≥ 10% reduced the lipid content in matured adipocytes. Consistently, higher doses significantly reduced cell viability, elevated reactive oxygen species levels, depleted intracellular glutathione levels, and accelerated apoptosis and cell necrosis. An interesting finding was that a DMSO dose of 0.01% improved glutathione content of 3T3-L1 adipocytes and had minimal effects on cell viability, apoptosis or and necrosis, supporting its antioxidant effect. Therefore, this study provides compelling evidence that precaution should be taken when assessing compounds dissolved in DMSO, particularly doses ≥1% that were shown to induce oxidative stress in 3T3-L1 adipocytes.

Cyclopia species are increasingly investigated as sources of phenolic compounds with potential as therapeutic agents. Recently, we demonstrated that a crude polyphenol-enriched organic fraction (CPEF) of Cyclopia intermedia, currently forming the bulk of commercial production, decreased lipid content in 3T3-L1 adipocytes and inhibited body weight gain in obese db/db mice. The aim of the present study was to determine whether a more effective product and/or one with higher specificity could be obtained by fractionation of the CPEF by purposely increasing xanthone and benzophenone levels. Fractionation of the CPEF using high performance counter-current chromatography (HPCCC) resulted in four fractions (F1–F4), predominantly containing iriflophenone-3-C-β-D-glucoside-4-O-β-D-glucoside (benzophenone: F1), hesperidin (flavanone: F2), mangiferin (xanthone: F3), and neoponcirin (flavone: F4), as quantified by high-performance liquid chromatography with diode array detection (HPLC-DAD), and confirmed by LC-DAD with mass spectrometric (MS) and tandem MS (MSE) detection. All fractions inhibited lipid accumulation in 3T3-L1 pre-adipocytes and decreased lipid content in mature 3T3-L1 adipocytes, although their effects were concentration-dependent. F1–F3 stimulated lipolysis in mature adipocytes. Treatment of mature adipocytes with F1 and F2 increased the messenger RNA expression of hormone sensitive lipase, while treatment with F1 and F4 increased uncoupling protein 3 expression. In conclusion, HPCCC resulted in fractions with different phenolic compounds and varying anti-obesity effects. The activities of fractions were lower than the CPEF; thus, fractionation did not enhance activity within a single fraction worthwhile for exploitation as a nutraceutical product, which illustrates the importance of considering synergistic effects in plant extracts.