Mangiferin (2C-β-d-glucopyranosyl-1,3,6,7-tetrahydroxyxanthone) is a xanthone C-glycoside occurring in many plant species. Composed of a glucose unit C1→2 linked to a 1,3,6,7-tetrahydroxyxanthone aglycone, mangiferin exhibits a wide range of biological activities, which recently renewed its interest as a potential pharmacophore. Mangiferin is mainly isolated after extraction procedures from natural sources alongside with its isoforms isomangiferin, homomangiferin, and neomangiferin. However, enzymatic and chemical approaches have been developed to access these phytochemicals, which address the challenging construction of the C-glycosidic linkage. In addition, both approaches have been exploited to modify the aglycone and the sugar moiety in order to afford analogues with specific and improved pharmacological activities. Herein, we provide a comprehensive review on the biosynthesis and chemical synthesis of mangiferin and its congeners. © 2016 BioFactors, 42(5):445-458, 2016.

Summary of main observation and conclusion An effective approach relying on a Lewis acid‐ or Brønsted acid‐assisted gold(I)‐catalyzed glycosylation has been reported in the synthesis of a panel of the representative natural spirostanol saponins, namely polyphyllin D (1), polyphyllin V (2), dioscin (3), formosanin C (4), and a derivative of polyphyllin D bearing a terminal azide group (5). This approach highlights the engagement of low loadings of Ph3AuPOTf (≤ 0.5 mol%) in the presence of Ga(OTf)3, In(OTf)3, or HOTf (~10mol%) as a co‐catalyst, at practical reaction rates as an alternative to the conventional ~10 mol% loadings of the gold(I) catalyst in the glycosylation. Polyphyllin D (1) was obtained in 41% overall yield over six steps compared to the maximum 30% yield in previous syntheses where conventional donors and promoters were used. By exploiting a regioselective rhamnosylation, a “one‐pot” approach was adopted to assemble 1 and 5, thus further strengthening the efficiency of the gold(I)‐catalyzed glycosylation.

Introduction: The study investigated the effect of an acclaimed immunoboosting herbal formulation, Averon  , which contains Aloe spp on some basal physiological and pathophysiological profiles in immunomodulated male rats. Materials and Methods: Six groups of male rats were used for the study: control group received water and pelletized food ad libitum, Negative control Cyclophosphamide-treated group (30mg/kg i.p), two groups pre-treated with Cyclophosphamide (30mg/kg i.p) and followed by oral 200mg/kg and 400 mg/kg Averon  respectively, two groups orally pre-treated with 200mg/kg and 400 mg/kg Averon  respectively and followed by Cyclophosphamide (30mg/kg i.p) on the last three days. The experimental design was characterized by observations for behavioral changes in the rats, changes in body weight, food consumption, water intake and gross histopathological changes after sacrifice. Results: The results revealed the adverse effects in the cyclophosphamide pre-treated groups in the behavioral pattern, significant decrease in body weights at several p-values, significant decrease in food intake (p< 0.05), significant drop in water consumption and toxicological effects on the studied organs. The reverse was true for the Averon  -pretreated groups: significant increase in body weights, food intake and water consumption. The adverse effect of cyclophosphamide was most pronounced on the lungs with little or no amelioration of the adverse effects on the pulmonary milieu. However, there was remarkable recovery on the livers, kidneys and the hearts on treatment with Averon  , particularly at the higher doses. Conclusion: Averon  showed tissue ameliorating potential except on the lungs, hence the need for therapeutic monitoring when administered to immunosuppressed subjects.

With the advent of Artemisinin Combination Therapy (ACTs) as the recommended treatment protocol for malaria by WHO, the menace of substandard and counterfeit anti-malaria drugs have been on the rise. Artesunate-amodiaquine, like other ACTs, has been widely implicated in this menace due to the market value and affordability. 13 representative brands of Artesunate/Amodiaquine were procured from different outlets in urban and peri-urban parts of Lagos, Nigeria. Quantitative and qualitative analysis were carried out on the different brands using HPLC. The results show all brands to contain the test APIs but in proportions varied about the USP specified limits. 30.8% of the test brands had artesunate within the USP specification. 30.8% of amodiaquine also had met the quality specification of USP. But only 15.4% of the sample had both amodiaquine and artesunate within the USP specification. 53.8% failed the active content test for both amodiaquine and artesunate.

As an innovative therapeutic strategy, drug repurposing affords old, approved, and already established drugs a chance at new indications. In the wake of the COVID-19 pandemic and the accompanied urgency for a lasting treatment, drug repurposing has come in handy to stem the debilitating effects of the disease. Among other therapeutic options currently in clinical trials, chloroquine (CQ) and the hydroxylated analogue, hydroxychloroquine (HCQ) have been frontline therapeutic options in most formal and informal clinical settings with varying degrees of efficacy against this life-threatening disease. Their status in randomized clinical trials is related to the biochemical and pharmacological profiles as validated by in vitro, in vivo and case studies. With the aim to bear a balance for their use in the long run, this review not only synopsizes findings from recent studies on the degrees of efficacy and roles of CQ/HCQ as potential anti-COVID-19 agents but also highlights our perspectives for their consideration in rational drug repositioning and use.

While repurposed drugs came in handy earlier in the wake of the coronavirus disease 2019 (COVID-19) pandemic, vaccination has been considered a more sustainable approach. The recent spikes have been linked to “double,” “triple,” and even multi-mutant variants, thus renewing calls for deeper structural and functional insights of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a lead to rationale design of therapeutics, vaccines, and point-of-care diagnostics. There is a repertoire of findings from the earliest SARS-CoV-2 molecular mimicry to evade host immunity cum host immune responses to the role of the viral glycocalyx in modulating the susceptibility and severity of infection through attraction and repulsive interactions. Recently, molecular studies of some viral components that aid infection in the face of vaccination seem unending. In addition, the wave of infections and the attendant case fatality ratios have necessitated the need for emergency use authorizations for COVID-19 vaccines and in vitro diagnostics. This review provides key updates of SARS-CoV-2, current antigenic and formulation strategies, with emergency use authorizations considerations for future vaccine candidates and diagnostics. We also premise that despite the difficulty in modeling and analyzing glycans, understanding and exploiting their roles in the SARS-CoV-2 architecture is fundamental to glycan-based COVID-19 vaccines devoid of inconsistent clinical outcomes.

Introduction: The World Health Organization (WHO) has recently declared the outbreak and spread of the new strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) a global pandemic. In this regard, a lot of scientific investigations and clinical trials on some existing antiviral and antibiotic drugs have been ongoing to combat this menace. Methods: In the past, conventional drug therapy has shown irregular drug distribution, poor solubility, and low permeability to target cells, organs, and tissues. However, Chloroquine, Hydroxychloroquine Remdesivir, Lopinavir/Ritonavir, etc. have attracted several investigations in mono-therapeutic approaches and a combination of therapy have shown promising effects in reducing viral loading in some SARS-CoV-2 infected patients. Never the less, the advent of nanomedicine has triggered serious attention on drug-loaded nanoparticle as nanocarriers to deliver bioactive drug molecules to target organs with increased circulation and controlled release. Therefore, the application of nanoparticles as nanocarriers for the controlled release of antiviral drugs would improve the ease of drug administration and care of patients admitted at various health care facilities worldwide. Conclusion: Owing to their small sizes, biocompatibility, and high encapsulation properties, nanoparticles can be utilized as potential nanocarrier of antiviral drugs for the SARS-CoV-2 management at a reduced cost with minimal side effect in the body system. In addition, some noticeable concerns on the ongoing management of SARS-CoV-2 pandemic in developing nations have been presented for concerted attention.