Herbal Medicine: Back to the Future

Curcumin and eugenol have been appreciated as broad-spectrum antimicrobial agents since the early 20th century, and their parent plants of turmeric and clove have been used in Ayurvedic and traditional Chinese medicines for thousands of years. Although extensive research has identified several antimicrobial mechanisms of action, it is the only eugenol that has become established for dental uses. Curcumin and eugenol have been hard to purify and stabilize and, in their native states, show poor bioavailability. New antimicrobial agents are now needed due to the growth in resistant strains, and this means natural agents are back in vogue. Nanoparticle and antimicrobial-coated surfaces are popular strategies to maximize the consistent delivery of mainstream pharmaceuticals. Computational chemistry and docking analyses are the primary methods used to identify and design novel variants of natural molecules to improve bioavailability and stability. Both curcumin and eugenol have benefitted from the expansion of these fields, and reports of stabilized forms with superior activity are now rapidly appearing in the literature. This chapter will review the antimicrobial spectrum of curcumin and eugenol, explaining their antimicrobial modes of action. Finally, potential and currently available delivery systems will be explored using the semi-synthetic analogs and bioengineered structures that have been created.

Herbal medicine is simply the science of using plants to treat or prevent medical conditions. It is one of the main modalities in traditional as well as contemporary medicine and is increasingly acknowledged due to the extensive use of herbal remedies in public and societies. As respiratory tract infections (RTI) are highly prevalent and variable, especially lower respiratory infections are a leading cause of sickness and mortality both in children and adults. There is a growing need for new treatments for such infections, particularly in the setting of worsening antibacterial resistance. Since ancient times, people who have tried herbs to treat diseases have also used them to treat infectious respiratory diseases. Many plants and herbal medicinederived natural products could be used as an alternative therapeutic potential for RTI since they have antibacterial, antiviral, and anti-inflammatory effects. Although there are some doubts about safety and efficacy, Chinese Herbal medicines may help treat symptoms of viral respiratory disease, including COVID-19. Natural products such as plant extracts and their active compounds, directly target the processes involved in RTI and could be suitable therapeutic options with fewer adverse effects. In the meantime, it should be kept in mind that there are many factors that affect the therapeutic potential of medicinal herbs and related products, including the collection and development processing. This section aims to highlight the examples of herbal medicines that are effective against RTI and their properties and therapeutic mechanisms.

Coronavirus disease 2019 has been declared a pandemic globally by WHO after its first emergence in Wuhan city of China. The disease was observed to be caused by SARS-CoV-2 infection. Although a complete spectrum of clinical manifestations linked with COVID-19 is yet to be determined, on the basis of virus evolution and genomic recombination; SARS-CoV-2 is believed to be belonging to the Coronaviridae family with the zoonotic origin, exhibiting several symptoms in human patients ranging from being asymptomatic to severe illness, ultimately leading to high mortality rate. Different molecular, serological, and radiological techniques have been employed to detect SARS-CoV-2 infection. Epidemiological insights have revealed that the infection has threatened the health and economy of all the nations worldwide. Diverse pharmacological interventions are already under place to fight against the current pandemic, and a few of them have already been approved by FDA. Natural products and herbal medicine could also play a prominent role as an alternative therapeutic approach to fight against the current pandemic, and few of their clinical trials have already been registered. The purpose of this chapter is to provide a comprehensive overview of the origin, genomic diversity & evolution, epidemiology, pathogenesis, transmission, diagnosis, possible therapeutic approaches of COVID-19, and experiential learning to enhance our preparedness for upcoming but unknown outbreaks.

Although a wide range of drug therapies fighting pathogenic agents have been developed since the late 19th century, infectious diseases such as pneumonia, flu, tuberculosis, AIDS and malaria still cost millions of lives. As per the World Health Organization (WHO) and Center for Infectious Disease Research estimates, the mortality rates of many infectious diseases may have actually worsened over the past few years. Development of new herbal compounds, understanding the effects of interactions between food and herbal medicines, and validating the traditional local combinations of plant use would be sophisticated revenues of research on the therapeutic effects of herbal medicine in infectious diseases. There is certainly a need for further collaborative biological screening of plant extracts in single, or combination forms and further interdisciplinary research in order to understand their interactions with biological systems. Infrared (IR) spectroscopy is a versatile analytical technique that has valuable applications in several areas such as biomedical sciences, pharmacy, engineering, chemistry, biophysics, food, plant science and toxicology. The combination of IR spectroscopy and chemometrics offers fast and powerful techniques for the separation and verification of herbal medicines-disease interactions. IR spectroscopy is widely used for the confirmation (identification), qualitative and quantitative analysis of herbal medicines and pharmaceutical products, and to determine how effective it is in the treatment of diseases. It requires small amounts of samples, and so is relatively nondestructive, accurate and does not require a reagent, so it is more ecofriendly than biochemical processes. There are only a limited number of published studies on the application of FTIR spectroscopy to herbal medicine - infectious disease interactions. Therefore, it is certainly a very promising and open research area.

Man's relationship with his environment has resulted in the development of a very rich traditional pharmacopoeia based mainly on medicinal plants. In Algeria, the plants uses are also oriented by scientific knowledge inherited from Muslim civilization in the books of Rhazes, Avicenna, Dawud El-Antaki, Ibn Beitar and Ibn Hamadouch. The infectious diseases known in the eighteenth and nineteenth centuries were treated by therapeutic formulas made from a plant, a mixture of plants or a mixture of plants and inorganic ingredients. Therefore, therapeutic formulas have been developed to treat measles, smallpox, urethritis, syphilis, malaria, tuberculosis, impetigo, scabies and yaws whose treatment has been imported to other countries and used successfully. These treatments can be prepared by infusion, decoction, maceration, trituration, fumigation, cooking and administered in drinks, eye drops, baths, soft dough and ointments. Currently, natural extracts of medicinal plants rich in biologically active chemical compounds have proven their antimicrobial, antiviral and antiparasitic potential in in vitro and in vivo studies. The valorization of plant medical resources provides effective alternatives in the treatment of these diseases and against the resistance of infectious agents.

Infectious diseases impose global challenges to public health. Infectious diseases can be caused by various pathogens, such as bacteria, parasites, fungi, or viruses. Over 1 million people worldwide die from viruses such as HIV, hepatitis C or B virus (HCV or HBV) in 2016. Recent outbreaks of Zika, Ebola and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) bring serious threats to global health security. On account of the high probability of an unpredictable virus pandemic, there is an urgent need for broad-spectrum antiviral drugs. Herbal medicine (HM) is a valuable source for the treatment of infectious diseases. A conventional traditional Chinese medicine (TCM) treatise ‘Shanghan Zabing Lun’, which recorded over 200 herbal formulae (known as Zhongjing’s formulae), also known in English as the ‘Treatise on Cold Damage Diseases’ has a history of around 1800 years. However, these ancient TCM formulae and theories are rarely used in nowadays methodologies for developing curative from HB. In this perspective review, we summarize the ancient theory of herbal medicine for treating infectious diseases including flu and malaria. The novel strategies for developing novel anti-infection drugs by modern integrated techniques for example, knowledge mining, high-content screening, phenotypic assays are also discussed, which will shed light on revealing novel properties and biological functions of phytochemicals inspired by ancient medical knowledge.