Growing evidence showed the increased prevalence of cancer incidents, particularly colorectal cancer, among type 2 diabetic mellitus patients. Antidiabetic medications such as, insulin, sulfonylureas, dipeptyl peptidase (DPP) 4 inhibitors and glucose-dependent insulinotropic peptide (GLP-1) analogues increased the additional risk of different cancers to diabetic patients. Conversely, metformin has drawn attention among physicians and researchers since its use as antidiabetic drug exhibited beneficial effect in the prevention and treatment of cancer in diabetic patients as well as an independent anticancer drug. This review aims to provide the comprehensive information on the use of metformin at preclinical and clinical stages among colorectal cancer patients. We highlight the efficacy of metformin as an anti-proliferative, chemopreventive, apoptosis inducing agent, adjuvant, and radio-chemosensitizer in various colorectal cancer models. This multifarious effects of metformin is largely attributed to its capability in modulating upstream and downstream molecular targets involved in apoptosis, autophagy, cell cycle, oxidative stress, inflammation, metabolic homeostasis, and epigenetic regulation. Moreover, the review highlights metformin intake and colorectal cancer risk based on different clinical and epidemiologic results from different gender and specific population background among diabetic and non-diabetic patients. The improved understanding of metformin as a potential chemotherapeutic drug or as neo-adjuvant will provide better information for it to be used globally as an affordable, well-tolerated, and effective anticancer agent for colorectal cancer.
SARS-CoV-2 is the latest worldwide pandemic declared by the World Health Organization and there is no established anti-COVID-19 drug to combat this notorious situation except some recently approved vaccines. By affecting the global public health sector, this viral infection has created a disastrous situation associated with high morbidity and mortality rates along with remarkable cases of hospitalization because of its tendency to be high infective. These challenges forced researchers and leading pharmaceutical companies to find and develop cures for this novel strain of coronavirus. Besides, plants have a proven history of being notable wellsprings of potential drugs, including antiviral, antibacterial, and anticancer therapies. As a continuation of this approach, plant-based preparations and bioactive metabolites along with a notable number of traditional medicines, bioactive phytochemicals, traditional Chinese medicines, nutraceuticals, Ayurvedic preparations, and other plant-based products are being explored as possible therapeutics against COVID-19. Moreover, the unavailability of effective medicines against COVID-19 has driven researchers and members of the pharmaceutical, herbal, and related industries to conduct extensive investigations of plant-based products, especially those that have already shown antiviral properties. Even the recent invention of several vaccines has not eliminated doubts about safety and efficacy. As a consequence, many limited, unregulated clinical trials involving conventional mono- and poly-herbal therapies are being conducted in various areas of the world. Of the many clinical trials to establish such agents as credentialed sources of anti-COVID-19 medications, only a few have reached the landmark of completion. In this review, we have highlighted and focused on plant-based anti-COVID-19 clinical trials found in several scientific and authenticated databases. The aim is to allow researchers and innovators to identify promising and prospective anti-COVID-19 agents in clinical trials (either completed or recruiting) to establish them as novel therapies to address this unwanted pandemic.
COVID-19, transmitted by SARS-CoV-2, is one of the most serious pandemic situations in the history of mankind, and has already infected a huge population across the globe. This horrendously contagious viral outbreak was first identified in China and within a very short time it affected the world's health, transport, economic, and academic sectors. Despite the recent approval of a few anti-COVID-19 vaccines, their unavailability and insufficiency along with the lack of other potential therapeutic options are continuing to worsen the situation, with valuable lives continuing to be lost. In this situation, researchers across the globe are focusing on repurposing prospective drugs and prophylaxis such as favipiravir, remdesivir, chloroquine, hydroxychloroquine, ivermectin, lopinavir-ritonavir, azithromycin, doxycycline, ACEIs/ARBs, rivaroxaban, and protease inhibitors, which were preliminarily based on in vitro and in vivo pharmacological and toxicological study reports followed by clinical applications. Based on available preliminary data derived from limited clinical trials, the US National Institute of Health (NIH) and USFDA also recommended a few drugs to be repurposed i.e., hydroxychloroquine, remdesivir, and favipiravir. However, World Health Organization later recommended against the use of chloroquine, hydroxychloroquine, remdesivir, and lopinavir/ritonavir in the treatment of COVID-19 infections. Combining basic knowledge of viral pathogenesis and pharmacodynamics of drug molecules as well as in silico approaches, many drug candidates have been investigated in clinical trials, some of which have been proven to be partially effective against COVID-19, and many of the other drugs are currently under extensive screening. The repurposing of prospective drug candidates from different stages of evaluation can be a handy wellspring in COVID-19 management and treatment along with approved anti-COVID-19 vaccines. This review article combined the information from completed clinical trials, case series, cohort studies, meta-analyses, and retrospective studies to focus on the current status of repurposing drugs in 2021.