Lauric acid vs. SARS-CoV-2
In this milieu, it is imperative to assess the suitability of coconut oil-derived lauric acid in treating COVID 19 caused by SARS-CoV-2. The potential positives for this proposition are SARS-CoV-2 is an enveloped virus with characteristic lipid membrane having S-glycoproteins (spike proteins) over its surface. The membrane disrupting role of lauric acid or its derivatives in the presence of SARS-CoV-2 is yet to be investigated. Considering the significance of early viral infection phase, wherein the virus encoded S-proteins effectively binds the human receptor protein angiotensin converter enzyme 2(hACE2), any disruption of viral membrane lipids could be detrimental to the viral infection process and thus could prevent the entry of virus into human cells. In this context, development of coconut oil based nasal spray either alone or in combination with other plant-derived essential oils, wherein the spray composition with anti-microbial, anti-inflammatory and decongestant attributes shows the great potential (Carolyn et al. 2012; Willimann 2018). Fatty acid molecules, preferably lauric acid and capric acid (both of which accounts for >60% of total fatty acids composition in coconut oil) have been developed into pharmaceutical formulations as mouth and throat rinse, nose and throat spray or nasal drops suitable for the treatment of respiratory syncytial virus (RSV). The efficacy of these virucidal formulations in decreasing the nasal viral load was demonstrated in mouse models without any off-target effects (Wyde et al., 2003). Thus, these instances highlight that development of lauric acid-based novel prophylactic or therapeutic measures would be of value to block the respiratory infections such as COVID-19 (Fig.1 ).
[Insert Fig. 1 here ]
Lauric acid as a food supplement was demonstrated to show no signs of toxicity on biochemical, histopathological profiles of animal models even at the dosage of 2,000 mg/kg body weight (Khan et al., 2020). Hence, considering the safety profile of lauric acid and coconut oil they can be recommended for satisfactory antiviral therapeutic purposes. It is further corroborated by the development of a proprietary antiviral formulation based on a short chain fatty acid (SCFA) (caprylic acid), ViraSAL. It’s efficacy in treating the enveloped viruses such as Epstein-Barr, measles, herpes simplex, Zika and orf parapoxvirus, together with Ebola, Lassa, vesicular stomatitis and SARS-CoV-1 pseudoviruses were proven in vitro and in vivo studies (Fletcher et al., 2020). These investigations further underscore the importance of SCFAs and MCFAs in the treatment of enveloped viruses due to its surfactant activity on the virus envelopes. Although monolaurin is widely available and generally recognized as safe (GRAS) by US-FDA, the chemical synthesis of coconut lauric acid-based monosaccharide esters and their anti-microbial characteristics are encouraging. These monosaccharide lauric acid esters are biodegradable, non-toxic and have wide medical applications yet antiviral properties are not proven (Mutmainah et al., 2019). Sodium lauryl sulfate (SLS) – a tensoactive agent which has detergent properties, is made from lauric acid. The broad spectrum surfactant activity of SLS has been instrumental in inactivating the human and animal infecting viruses such as human immunodeficiency virus (HIV), human papillomavirus (HPV) and herpes simplex virus (HSV) (Piret et al., 2002) and in demonstrating microbiocidal activities against the viruses infecting small ruminants (de Souza 2019). A functional monoglyceride (MAG) has been developed by esterifying lauric acid and its anti-microbial activity was demonstrated while using it as a food preservative (Luna et al., 2020).
Furthermore, investigations have shown that monolaurin has anti-inflammatory effects in rhesus monkey models in response to HIV-1 and SIV infections (Li et al., 2007). Monolaurin suppresses inflammatory immune responses including the repression of IL-6 (Interleukin -6) production. Zhang et al (2017) has attributed this effect to the disrupted lipid dynamics in the T-lymphocytes. The effect of monolaurin in lowering the levels of IL-6 in COVID-19 patients opens a new avenue for the designing of novel therapeutics to block SARS-CoV-2 since it has been demonstrated that production of pro-inflammatory cytokines such as IL-6 leads to extreme inflammation of bodily parts resulting in acute respiratory distress syndrome (ARDS) associated with the disease (Liu et al., 2019). Inhalation of virgin coconut oil (VCO) reduces the inflammatory responses and relieves asthma related symptoms in rabbit models of allergic asthma (Kamalaldin et al., 2017) further substantiating the therapeutic potential of coconut oil. Nevertheless, prophylactic application of VCO did not evince any relief for allergic asthma (Kamalaldin et al., 2017).