Introduction
Coconut (Cocos nucifera L.) is a tropical palm which is
aptly called ‘tree of life’ (kalpavriksha ) as it supplies wide
range of food products of human consumption viz ., coconut oil,
tender nut water, endosperm, inflorescence-sap derived sugar etc. Among
this coconut oil has been attributed with many nutritional and
health-conferring properties owing to its unique fatty acid composition
(Dayrit 2014). The principal biochemical components of coconut oil and
their potential health benefits are presented in Table 1 (Table
1 near here) . Coconut oil is rich in medium chain triglycerides (MCTs)
due to the predominance of C6 to C12 fatty acids attached to the
glycerol moiety. Coconut oil derived-MCTs are easily soluble and
digestible by salivary and pancreatic lipases in comparison to
triglycerides of other vegetable oils which are predominantly long chain
triglycerides (LCTs). Lauric acid (C12) is one of the prime medium chain
fatty acids (MCFAs) and its content in coconut oil varies from 45-53%
(Dayrit 2014). Around 60% of the coconut triacyl glycerol (TAG)
comprises MCFAs (both lauric acid and capric acid) in its positionssn-1 , and sn-3 (Dayrit 2014). Studies have demonstrated
that proportion of dietary MCTs determines their mode of absorption as
LCFAs predominantly enter the lymphatic system whereas MCTs are absorbed
through portal veins (Mc Donald et al., 1980). Differential absorption
of MCTs ensures their faster digestion, absorption and rapid energy
expenditure thereby alleviating adiposity in humans (St-Onge et al.,
2003). Besides their hypolipidemic effects, MCTs are known to have
antimicrobial effects. Most conspicuously, lauric acid and its
monoglyceride derivative, monolaurin, have been demonstrated to possess
anti-microbial properties against gram positive bacteria (Projan et al
1994, Peterson et al., 2004), and many viruses such as Junin virus
(JUNV), vesicular stomatitis virus, Simian immunodeficiency virus (SIV)
etc. infecting humans (Thormar et al., 1987; Hornung et al., 1994;
Bartolotta, et al., 2001; Duke 2009; Li et al., 2009).
Administration of coconut oil has been found to be an effective remedy
for the treatment of many of the enveloped viruses such as such as
Cytomegalovirus, Epstein-Barr virus, hepatitis C virus, influenza virus,
leukemia virus (Enig 2010; Dayrit 2000; Fife 2013). The antiviral
property of monolaurin has been attributed to its common role in
disrupting the phospholipid layers in the membranes of the enveloped
viruses causing their ultimate disintegration. Monolaurin has adverse
effects on the virus assembly and maturation phases of infection cycle
eventhough the viral RNA and protein synthesis are unimpeded (Hornung et
al., 1994). The binding of viral M protein (membrane) to the host cells
was compromised due to the presence of lauric acid (Hornung et al.,
1994). Supplementation of MCTs such as lauric acid induces cellular
biosynthesis of triacylglycerols (TAG) in the infected cells (Hornung et
al., 1994; Bartolotta, et al., 2001). This spurt in the biosynthesis of
TAGs deprives the viruses of its crucial process, glycoprotein insertion
in the plasma membrane, consequently interrupting the virus maturation
process (Hornung et al., 1994; Bartolotta, et al., 2001). However,
direct inactivation of virion particles of other enveloped viruses such
as HIV and HSV due to physical contact with MCFAs is also not uncommon
(Kristmundsdottir et al., 1999; Kohn et al., 1980). Antiviral properties
of coconut oil-derived lauric acid or direct application of coconut oil
have been established in animal studies. Administration of virgin
coconut oil (VCO) through feed has enhanced the immunity parameters of
chickens following challenge test with Avian influenza A virus subtype
H5N1 (Yuniwarti et al., 2015).
COVID-19 (Coronavirus disease-2019), the pandemic caused by novel SARS
Coronavirus (SARS-CoV-2) has been wreaking havoc in the global health
sphere. At this point of time no specific drugs are therapeutic agents
are prescribed to control the disease eventhough clinical trials are
on-going. As the number of confirmed COVID-19 cases are increasing
(3.517 million cases and death toll of 2,43,401 as on 5/ May/2020)
(https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200505covid-19-sitrep-106.pdf?sfvrsn=47090f63_2)
lot of interests have been generated towards identification of compounds
of plant origin with antiviral potential. These developments have
renewed the interests in studying coconut oil and its variant virgin
coconut oil (VCO) against COVID-19. Philippine Council for Health
Research and Development (PCHRD) and Department of Science and
Technology (DOST) has announced a hospital-based project entitled
“Virgin Coconut Oil and Omega-3a Adjunctive Therapy for Hospitalized
Patients with COVID-19”
(https://www.covid19.gov.ph/dost-to-study-benefits-of-virgin-coconut-oil-on-covid-19-patients).
In this context, this communication presents the pros and cons of
developing the coconut oil and its products-based treatment for COVID-19
with special emphasis on biochemical basis of antiviral properties.