This document discusses oligonucleotides and their potential use for treating COVID-19. It defines oligonucleotides as short nucleic acid chains usually consisting of around 20 nucleotides. It describes how oligonucleotides can be designed to target mRNA from mutated genes in order to treat genetic disorders. The document outlines different drug delivery systems and categories of oligonucleotide therapeutics, including antisense oligonucleotides and aptamers. It proposes that oligonucleotides could provide an attractive option for treating COVID-19 through development of antiviral drugs or therapies targeting the virus's spike protein or replicative proteins.

1. OLIGONUCLEOTIDES
Paramjeet Kaur
M.Pharma,2nd sem
Pharmaceutics
Submitted to: Dr. Chitra Gupta
College: LLOYD Institute of Management and Technology

2. CONTENTS
• INTRODUCTION
• OLIGONUCLEOTIDE DRUG DELIVERY SYSTEM
• TYPES OF OLIGONUCLETIDE DDS
• OLIGONUCLEOTIDE AND COVID-19 PANDEMIC
• PK AND PD PROPERTIES
• APPLICATIONS
• LIMITATIONS
• REFRENCES

3. INTRODUCTION
DEFINITION : A short nucleic-acid chain usually consisting
of approximately 20 nucleotides
• They have a wide range of applications in genetic testing,
research, and forensics.
• Commonly made in the laboratory by solid-phase
chemical synthesis, these small bits of nucleic acids can
be manufactured as single-stranded molecules with any
user-specified sequence, and so are vital for artificial
gene synthesis, polymerase chain reaction (PCR), DNA
sequencing, molecular cloning.

4. INTRODUCTION
• In nature,oligonucleotides are usually found as small RNA
molecules that function in the regulation of gene regulation
(eg. micro RNA)or are degradation intermediates derived
from the breakdown of large nucleic acid molecules
• Oligonucleotides are composed of 2'-deoxyribonucleotides
(oligodeoxyribonucleotides), which can be modified at the
backbone or on the 2’ sugar position to achieve different
pharmacological effects. These modifications give new
properties to the oligonucleotides and make them a key
element in antisense therapy.

5. STRUCTURE AND MODIFICATIONS OF
OLIGONUCLEOTIDE:

6. How to stop genetic disorder using DNA
drugs:
• Design a short DNA sequence that matches the sequence
of mRNA that is transcribed from the mutated gene (which
cause disease)
• The DNA drug binds to the mRNA
• The mRNA cannot be translated to proteins
• Because no disease - causing protein, disease is cured

7. OLIGONUCLEOTIDE DRUG DELIVERY
• Strategy of therapeutic
oligonucleotidesis divided into
four categories as folllow:
• A) Single piece of oligonucleotide
• B) Oligonucleotide-ligand
conjugate
• C) Oligonucleotide-polymer
conjugate
• D) Nanoparticles

8. CATEGORIES OF THERAPEUTIC
OLIGONUCLEOTIDES

9. ON THE BASIS OF MOA
• Therapeutic oligonucleotides, on the basis of mechanism
of action is divided into 2 categories, as follow:
A. Antisense Oligonucleotide
B. Modulator of protein activity (Aptamers)

10. A) ANTISENSE OLIGONUCLEOTIDES
• ASO can interact with both pre -RNA in the nucleus and
mature mRNA in the cytoplasm
• An Antisense oligonucleotide (ASO) is a single stranded
deoxyribonucleotide ,which is complementry to mRNA
target
• They mainly inhibit the protein translation process
• ASO can reduce or increase gene expression via 3
mechanisms- a) mRNA maturation
b)RNase H-mediated degradation
c)Steric translation inhibition

11. • A) ANTISENSE
OLIGONUCLEOTIDE
are the molecules made of
synthetic genetic
material,which interact with
natural genetic material
that codes
the information for
Production of proteins.

12. B) Modulator of protein activity (APTAMERS)
• Aptamers are short, single-stranded DNA or RNA (ssDNA or
ssRNA) molecules that can selectively bind to a specific target,
including proteins, peptides, carbohydrates, small molecules,
toxins, and even live cells.
• They are extremely versatile and bind targets with high
selectivity and specificity.
• Range in size from 20 - 80 bases.

13. Aptamer mechanism of binding:

14. Ologonucleotides and the COVID-19 Pandemic
• Presently, no effective drug treatments for the disease have
been readily identified; however, a host of compounds—about 12
in total—are being tested, including drugs already approved for
use against HIV and malaria, a number of experimental
compounds shown to exhibit antiviral activity in animal testing,
and even antibody-rich plasma taken from those patients who
have successfully recovered from the virus.
• oligonucleotide drugs developed either as antiviral or symptom-
alleviating approaches to COVID-19 could prove to be an
attractive option due to their rational design and relative speed of
development compared with traditional approaches.

15. COVID infectious
pathway and
targets of disease

16. oligonucleotide based therapy
• Viable oligonucleotide-based therapeutic strategies can,
therefore, opt to target either the virus itself by inhibiting its
spike protein or interfering with its replicative proteins through
protein–nucleic acid interaction—as in an aptamer—or by
directly targeting its large genome through small interfering
RNA (siRNA) or antisense oligonucleotide (ASO)-mediated
gene silencing.
• An immediate consideration is the huge size of the viral
genome in CoVs, offering many possible targets for oligo-based
therapeutics since they function through simple Watson–Crick
base pairing.

17. • Oral bioavailability is generally very low (1-3%)
• 30-40% of oligonucleotides having at least one nucleotide
removed after 5 min in plasma
• Endonuclease -mediated degradation of oligonucleotides is
generally not observed
• Oligonucletides are that
protect them from renal filtration
• Urinary excrition is a major route of excretion for
oligonucleotides,regardless of sequence or chemical
structure,with the majority being short length metabolites rather
than unchanged parent drug

18. APPLICATIONS:
• Various therapeutic areas for eg. :Oncology,
Opthalmology, Vaccines and other biotechnology
applications.
• As Antiviral and Antibacterial agents.
• As CVS and CNS therapeutics
• Fomivirsen for treatment of CMV retinitis in AIDS patients
• Defibrotide for treatment of veno - occulsive disease in
liver
• Mipomersen for high cholesterol

19. OLIGONUCLEOTIDES also play vital role in:
• DNA sequencing: Determination of nucleotide sequence
in DNA molecule.
• PCR: In-vitro technique of generating large quantity of
specified target DNA.
• Artificial gene synthesis (DNA printing)
• Molecular Cloning: introducing recombinant DNA
molecule and direct their replication within host organism.
• Genetic testing,research,and Forencics

20. Antisense drugs used to treat various diseases:
• Lung cancer
• colorectal carcinoma
• Pancreatic carcinoma Malignant melanoma diabetes
• Muscular dystrophy Asthma
• Arthritis

21. LIMITATIONS:
• Accessible sites of the target RNA for oligonucleotide
binding have to be identified.
• antisense agents have to be protected against nuclease
enzyme attack.
• Cellular uptake and correct intracellular localization.
• It is necessory to chemically modify antisense
oligonucleotides to make them stable in cells.
• large dose required for therapeutic response.
• The half life in plasma is short.

22. REFRENCES:
• U. Satyanarayana, U. Chakrapani, “Biochemistry” 5th Ed.
(2017), Elsevier
• P.S. Verma, V.K. Agarwal, “Cell Biology: Cytology,
Biomolecules and Molecular Biology” 1st Ed. (2016), S.
Chand and Company Pvt. Ltd
• B.D. Singh, “Genetics” 2nd revised Ed. (2009), Kalyani
Publishers
• https://www.liebertpub.com/doi/10.1089/NAT.2020.0868
• https://www.oligotherapeutics.org/oligonucleotide-
therapies-and-covid-19/