# An Update of Carbazole Treatment Strategies for COVID-19 Infection
## 4 Carbazoles Treatment  
Several studies [5; 9; 17; 45; 46; 47; 48; 49; 50; 51; 52; 53; 54; 55; 56; 57; 58; 59; 60; 61; 62] describing the important role of carbazole derivatives in the treatment of COVID-19 are included in this review, cf. Table 1. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Compound** & **Name** & **Reference** \\ \hline SARS-CoV-2 M-pro inhibitors & & \\ \hline
1 &
\begin{tabular}{c} Carprofen \\ 2-(6-Chloro-9\(H\)-carbazol-2 yl)propanoic acid \\ \end{tabular} & [45] \\ \hline
2 &
\begin{tabular}{c} Carvedilol \\ 1-(9\(H\)-Carbazol-4-yloxy)-3-[2-(2-methoxy)) \\ ethylamino]propan-2-ol \\ \end{tabular} & [5; 9; 17; 46; 47; 48; 49; 50; 51; 52] \\ \hline
3 &
\begin{tabular}{c} Koenigicine \\ 8-Methoxy-3,3,5-trimethyl-11\(H\)-pyrano[3,2-\(a\)]carbazol-9-ol \\ \end{tabular} & [53] \\ \hline
4 &
\begin{tabular}{c} Mukonicine \\ 9,11-Dimethoxy-3,3,5-trimethyl-11\(H\)-pyrano[3,2-\(a\)]carbazole \\ \end{tabular} & [53] \\ \hline
5 &
\begin{tabular}{c} O-methylmurayama \\ 9-Methoxy-3,3,5-trimethyl-11\(H\)-pyrano[3,2-\(a\)]carbazole \\ \end{tabular} & [53] \\ \hline
6 &
\begin{tabular}{c} Koenine \\ 3,3,5-Trimethyl-11\(H\)-pyrano[3,2-\(a\)]carbazol-8-ol \\ \end{tabular} & [53] \\ \hline
7 &
\begin{tabular}{c} Grinimbine \\ 3,11-Dihydro-3,3,5-trimethyl-pyrano[3,2-\(a\)]carbazole \\ \end{tabular} & [53] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Carbazole derivatives-based drugs for the treatment of COVID-19. Carbazole containing heterocycles can be of synthetic or natural origin, many are alkaloids extracted from the leaves of _Ochrosia Elliptica Labill_[63]. Carbazoles represent an interesting class of heterocycles known by their anticancer activity [64,65]: antibacterial, anti-inflammatory [66], antifungal, antioxidant, antimicrobial, antiepileptic, antihistamine, antiviral [67,68]. In addition, numerous carbazole derivatives have also been found to be useful for [PERSON]'s disease [69]. Several carbazoles were assessed by research groups for a SARS-CoV-2 virus study [5,45,53,54,56,57,58,59,60,70]. Despite vaccination against COVID-19, there is an urgent priority to identify additional antiviral drugs due to immune loss due to new variants of SARS-CoV-2; computational approaches have made a big contribution to the identification of antivirals by lowering costs and time and by accelerating analyzes of target interactions with candidate drugs [45,71]. A therapeutic strategy for drug development is the targeting of the main protease (Mpro) for its important role in the viral replication cycle. The overlapping polyproteins (pp1a and pp1 ab) are cleaved, in an autoproteolytic way, by SARS-CoV-2 Mpro (SC2-Mpro), and mature non-structural proteins (11 proteins) necessary for viral replication and transcription are produced [72]. The lack of a Mpro-like human protease, such as its unique selective ability of cleavage site, makes it a major therapeutic target for the detection of anti-SARS-CoV-2 drugs [53,70]. Moreover, ACE2 is used as a therapeutic target to control the COVID-19 outbreak, as an ACE2-mediated mechanism allows the virus to enter permissive cells. ACE2 has a defensive role in heart disease as it is a membrane-bound zinc metallopeptidase that produces the vasodilator peptide angiotensin 1e7 [54]. Additionally, in order to identify new anti-COVID-19 drugs, an interaction between the SARS-CoV-2 nucleoprotein (N) and the cholesterol transporter Niemann-Pick type C1 (NPC1) [59] was evaluated. The NPC1 receptor, an endosomal membrane protein, regulates intracellular cholesterol transport. Another important protein