Combinatory in silico investigation for potential inhibitors from Curcuma sahuynhensis Š korni č k. & N.S. Lý volatile phytoconstituents against in ﬂ uenza A hemagglutinin, SARS-CoV-2 main protease, and Omicron-variant spike protein

: Curcuma sahuynhensis Š korni č k. & N.S. Lý has been discovered recently whose antiviral potential is unknown, thus deserved for discovery-phase screening. A combination of experimental characterization, quantum calculation, molecular docking simulation, physicochemical analysis, and absorption, distribution, metabolism, excretion, and toxicity (ADMET) was designed for the theoretical argument on the potentiality of oil-based components (1 − 27) against H5 hemagglutinin in in ﬂ u-enza A virus (PDB-5E32), wild-variant SARS-CoV-2 main protease (PDB-6LU7), and SARS-CoV-2 Omicron spike protein (PDB-7T9J). Theoretical arguments based on various computational platforms specify the most promising bio-inhibitors, i.e. 23 (bio-compatibility: ground energy − 966.73 a.u., dipole moment 3.708 Debye; bio-inhibitability: DS̅ − 12.5 kcal mol − 1 ; drug-like-ness: mass 304.7 amu, log P 1.31; polar-interactability: polarizability 32.8 Å 3 ) and 26 (bio-compatibility: ground energy − 1393.66109 a.u., dipole moment 5.087 Debye; bio-inhibit-ability: DS̅ − 11.9 kcal mol − 1 ; drug-likeness: mass 437.5 amu, log P 4.28; polar-interactability: polarizability 45.7 Å 3 ). The pkCSM-ADMET model con ﬁ rms their favorable pharmaco-kinetics and pharmacology. The total essence is unsuitable for use as an antiviral source in its pure form since the most bioactive candidates are accountable for the small content. Particularly, 23 (7 β -hydroxydehydroepiandrosterone) and 26 (ethyl cholate) are recommended for further experimental e ﬀ orts of isolation and bioassaying trials.


Introduction
Curcuma L. is one of the largest genera of the ginger family, Zingiberaceae, with approximately 130 recognized species (https:// powo.science.kew.org/taxon/urn:lsid:ipni.org:names:331178-2, April 2023, Accessed: 12.04.2023).These rhizomatous herbaceous perennials are widely distributed in tropical and subtropical regions, especially in South-to-Southeast Asia and Northern Australia.In Vietnam, 28 Curcuma species have been previously scientifically described [1] with some morphological similarities, e.g., few-flowered cone-like inflorescence, congested bracts, straight trunk, and spurred anthers [2].Besides being delightful ornamental plants, members of the Curcuma genus are well known for being an essential source of flavoring agents and cosmetics in Asian cultures [3].According to folk experience, they are known for various pharmacological properties, e.g., antioxidant, anti-inflammatory, antiproliferative, antimicrobial, hypotensive, hypoglycemic, hepatoprotective, and neuroprotective activities.Curcuma longa (turmeric) and Curcuma zedoaria (zedoary) are the most extensively investigated species due to their great commercial value [4].Nevertheless, other Curcuma species have been studied to a narrower extent.
Curcuma sahuynhensis Škorničk.& N.S.Lý is an endemic species in Curcuma subgenus Ecomatae, which was first discovered and described in 2015 in Quang Ngai Province, Vietnam [5].Its morphological characteristics with all parts of the plants are shown in Figure 1.This rhizomatous herb has a void to narrowly ovoid and slightly aromatic rhizomes.Mature plants can reach 80 cm in height, with up to 10 leaves in ovate-to-elliptic shapes.Its flowers typically bloom from August to October annually.Generally, C. sahuynhensis shares several similar morphological traits to some other subgenus Ecomatae in Vietnam, namely Curcuma newmanii, Curcuma singularis, and Curcuma xanthella.Inflorescences of the herb are often harvested as vegetables for a meal by resident people [5].To the best of our knowledge, since the time of the first description (2015), there have been only two reports on chemical and biological characteristics.In 2020, Sam et al. presented the first phytochemical analysis and bioactivity screening of C. sahuynhensis, which revealed its activity against a variety of gram-positive bacteria (Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus) and a pathogenic yeast (Candida albicans) [6].More recently, in 2022, Van Chen et al. [7] published a paper on macro-and micro-morphological features, physicochemical parameters, phytoconstituents, and powder characteristics of the herbs.The authors also carried out a preliminary pharmacognostic screening by comparing the detected phytochemicals with the bioactivities of those already known to the literature; yet, no concrete evidence was established.Despite its local popularity and promising bioactivity, the potentiality of C. sahuynhensis is still vastly untouched by scientific communities, probably because of its highly regional endemics (only in Quang Ngai province, Vietnam).Therefore, more efforts, especially on the phytochemical-activity relationship, are required to allocate better the biological potential, thus reasoning further pre-clinical attempts.However, conventional trial-and-error lab-based tests are considered cost-and time-ineffective given the bio-versatility of natural products.
Regarding general bioactivity, natural essential oils are often classified into four groups based on their structure: monoterpenes, oxygenated terpenes, terpene esters, and sesquiterpenes.Typically, these substances have significant biological activity, especially antiviral potentiality.The most prominent essential oil constituent is monoterpenes obtained by liquid extraction and steam distillation of edible and medicinal plants [8].Many research attempts have demonstrated that monoterpenes exhibit antibacterial, antiviral, and antifungal properties.For example, Eucalyptus oil and its active component, 1,8-cineole, were reported to possess in vitro antiviral activities against various strains of viruses, including enveloped mumps viruses (MV) and herpes simplex viruses (HSV-1 and HSV-2) [9].Recently, β-caryophyllene, a sesquiterpene, was found as the major compound of essential oil from Lippia alba and demonstrated for its antiviral activity against Zika virus (ZIKV) in vitro and in silico [10].In terms of diterpenes, many candidates have been shown to have antiviral activity, including kirkinine, excoecariatoxin (anti-HIV) [11], jiadifenoic acids (anti-Coxsackie virus) [12], briaexcavatolide U, and briaexcavatin L (anti-HCMV) [13].Certainly, this review is far from complete, indicating the enormous potential of natural essential oils in general for their antiviral activities and those extracted from C. sahuynhensis in particular.
Over the last few years, the outbreaks of dangerous viral infections have raised serious concerns as they are causing pandemics on a worldwide scale and pressuring the global healthcare systems.This means searching for demotic and editable sources with antiviral activities is necessary as food-and-drug recommendations for daily use as supplements to improve public health.Typically, the most prevalent diseases include those caused by influenza and SARS (recently, SARS-CoV-2) viruses.The former includes three types, named A, B, and C types, which cause respiratory illness with flu-like symptoms.Patients infected with influenza types A and B often face more serious-to-fatal complications.The influenza virus designation refers to the two components that envelope the virus's surface, hemagglutinin (HA) [14] and neuraminidase (NA) [15].HA protein is required for the virus to attach to the glycoprotein or glycolipid in the host cell membrane through multivalent connections to sialoglycans, enabling the propagation of freshly manufactured virus inside the host.Hence, this structure is considered a high-potential target for bioactive inhibition by halting the intrusion.NA protein is a glycoside hydrolase enzyme required for viral replication.In the case of SARS-2 viruses, the effects have been prevalently recognized over the last 3 years from the views of both healthcare and the economy.Shortly after the first breakout, the genome of CoV was found to encode two proteins, designated as PPLA and PPLB [16], involving infection, replication, and polymerase activities [17].The polyprotein is synthesized after transcription/translation steps and is then proteolyzed to yield nonstructural proteins.Two cysteine proteases, e.g.Papain-like protease and 3-chymotrypsin-like protease (also known as Mpro), mediate proteolytic processing.By mechanism, effective Mpro inhibitors might prevent viral replication [18], thus considered the most appealing target for SARS-CoV-2 treatments.Concerning its mutability, Omicron variants include over 50 mutations, at least 30 of those located in the spike protein.This protein is composed of two subunits, i.e.S1 and S2, particularly essential for viral adhesion to host cells, and the second is responsible for virus-cell membrane fusion [19,20].From clinical observations, not only the increase of transmissibility and virulence but also the reduction of vaccination efficacy was reported relating to the infection of Omicron variants.This means that the protein structure is also promising.
By harnessing computer-based power, in silico research can compensate for the cost and time disadvantages of labbased experimental trials to quickly allocate the most promising biological candidates.In fact, the applicability of computational chemistry has been seen extensively in a broad range of bio-physico-chemical aspects, such as virology [21], oncology [22], neurology [23], or the development of drug-delivery nanocarriers [24].With the appropriate combination of the views from different computational platforms, the theoretical analysis can provide more reliable predictions and, thus, results with higher accuracy.For example, the electronic properties of a chemical structure, e.g., electronic stability, dipole moment, and potential distribution, can be obtained from an ab initio calculation, which in turn can be used for argument on intermolecular interactability.Besides, molecular docking simulation is a useful technique often exploited for the prediction of ligand-protein inhibitability based on the interacting conformation of a potential inhibitor and selective sites [25].Most algorithms are simply based on the static pseudo-Gibbs free energy between the two participants [26], giving them the light-duty leads; on the other side, the pre-docking conditions, representing physio-chemical resistance, are often omitted.Fortunately, this downside can be solved by the incorporation of other computational platforms, e.g.statistically regressive models, to retrieve the missing physicochemical effects.Similarly, the pharmacokinetics and pharmacological properties of a promising phytochemical can be predictable using available special-purpose regressive models, e.g.SwissADME.These computational implementations, coupled with consistent arguments, can screen a large number of compounds for their potentiality on both biological compatibility and pharmacological suitability.
In this work, a variety of in silico platforms was used in combination to predict the antiviral activities of the phytochemicals in C. sahuynhensis rhizome n-hexane fraction.The input for the computational implementations was the data collected from experiments.The biological targets were important protein structures of the influenza virus and SARS-CoV-2.Currently, there is little knowledge on C. sahuynhensis collected in the literature; therefore, the results can serve as the justification for more selective attempts to exploit the natural source.

Plant material
Fresh rhizomes of C. sahuynhensis were collected from Quang Ngai Province, Vietnam (Figure 1).The scientific name of the plant was identified by Dr. Nguyen Thanh Triet.The study sample was profiled by DNA-based identification and approved as the public database by GenBank under the code OM021341.1 (https://www.ncbi.nlm.nih.gov/nuccore/2170415927, April 2023, Accessed: 12.04.2023).A voucher specimen (sample code: CS-11.21) was deposited at the Laboratory of Traditional Medicine, Faculty of Traditional Medicine, University of Medicine and Pharmacy at Ho Chi Minh City.

Chemical extraction
After harvesting, the rhizomes were soil-removed, washed and dried at room temperature, and ground into middlings before being subjected to chemical extraction.Powdered rhizomes of C. sahuynhensis (300 g) were under percolation-based extraction with ethanol (96%), yielding a total extract.The solvent was removed by a rotary evaporator at 45 ± 2°C, leaving a crude extract.The crude extract was under liquid-liquid distribution with n-hexane to obtain respective fractional extracts.The n-hexane fraction was preserved at low temperatures (4°C).

Gas chromatography-mass spectrometry (GC-MS)
The chemical constituents of C. sahuynhensis rhizome nhexane fraction were identified using GC-MS: Agilent GC 7890B-MS 5975C instrument coupled with a DB-5MS column (30 m × 0.25 mm × 0.25 µm).The n-hexane fraction 1.0 (µL) was injected into the GC column with a 20:1 split ratio; GC temperature program: (i) initiating at 70°C for 1 min (for isothermal condition); (ii) increasing linearly to 300°C at the rate of 20°C min −1 (for 20 min) with the inlet temperature set at 250°C; MS configurations: MS transfer line temperature and ion source temperature with 230°C; EI mode with 70 eV ionization voltage; sector mass analyzer scan from 29 to 650 amu.Helium was used as the carrier gas with a constant flow rate of 1.2 mL min −1 .NIST-17 database was used as the standard spectral reference.

Quantum calculation
Density functional theory (DFT) was used for the calculation of molecular quantum properties.Software used were Gaussian 09 for calculation and GaussView 05 for visual rendering.Configurations used were no symmetry constraints [27]; functional M052X and basis set 6-311++g(d,p) for geometrical optimization [28,29]; functional M052X and basis set def2-TZVPP for molecular electrostatic potential (MEP) calculation; and imaginary frequency check for non-transitional state.Approximations were frozen-core method and resolution-ofidentity technique.Termination was self-consistent field convergence at 10 −8 a.u.; integration grid "m4."

Docking simulation
The molecular docking technique was used for the simulation of ligand-protein static interaction.MOE 2015.10 software was used [30].The procedure is as follows: input, docking, checking, and interpretation.
( Chemical formulae for ligands were identified by GC-MS in this work; configuration: Conj Grad optimization, Gasteiger-Huckel charge assignment.(ii) Docking simulation: The interaction between the selected ligand and its targeted protein was run by MOE 2015.10.(iii) Checking iteration: The simulated participants (protein and ligand) were allowed for a re-docking implementation to check the root-mean-square deviation (RMSD) value of the backbone atoms.The value under 2 Å is understood as a reliable result.(iv) Theoretical interpretation: The results include 2D interaction maps, 3D conformational visualization, and other inhibitory parameters (docking score [DS] energy, RMSD value, and counts of binding bonds).In particular, DS energy is often interpreted as the pseudo-Gibbs free energy, i.e., the formation energy of the associated ligand-protein complex, thus considered as primary parameters for inhibitory effectiveness.
Figure 2 presents the input for ligands in this work; the structural formulae were from the experiments, i.e., extraction and GC-MS.Figure 3 shows the crystal assemblies of the protein used in this work and the control drugs; the data were referenced from RCSB-Protein Data Bank.

Chemical composition of n-hexane fraction
Table 1 summarizes major volatile bioactive compounds in the n-hexane fraction of C. sahuynhensis rhizomes identified by GC-MS and their notation used in this report.In this screening stage, the standards of found compounds were not used for exact quantitative measurement; instead, the peak areas were addressed as a preliminary discussion on their contents.In total, there are 27 components detected.
In particular, methyl palmitate (14; peak area 11.77%), methyl linoleate (18; peak area 9.03%), ethyl palmitate (16; 6.18%), ethyl linoleate (21; 4.26 peak area %), humulene oxide II (11; peak area 3.82%), and ambrial (13; peak area 3.79%) appear to be present as the components with significant amount.They likely comprise the major proportion of the essence, thus of special interest, thanks to their bioavailability.More generally, most compounds register the area values ca.1-3%, likely accounting for the minor portions, and can be considered for isolation and application if predicted valuable enough.Otherwise, the constituents with likely negligible percentages (peak areas <1%) either hold low contributions to the total effect of the essential oil or are not deserved for cumulative enrichment from the economic standpoint.On the other hand, those with both promising bio-activities and potential bioavailability should be subjected to quantitative evaluation to measure the actual concentrations and validate their portions in the total essence.In general, the major compounds detected in C. sahuynhensis essential oil have been demonstrated with diverse bio-active properties by other works.Methyl palmitate has been reported to have anti-inflammatory [36], anti-arthritic [37], acaricidal [38], antioxidant, insecticide, hemolytic, and hypocholesterolemic [39,40] properties.Ethyl palmitate has been determined to have anti-inflammatory, antioxidant, anti-androgenic, hemolytic, hypocholesterolemic, and antimicrobial activities [36,39,41].Methyl linoleate has been identified as a bioactive anti-adipogenic [42] and anti-melanogenesis agent [43].Ethyl linoleate has been proven to exhibit anti-inflammatory, antioxidant, and anti-acne activities [44][45][46].Transparently, this review is incomplete; yet, the compounds are unlikely to be characterized by antiviral properties.This means that the activities against viruses (if  any) are more likely allocated to those with moderate proportions, thus conducive to applying bioactive versatile natural products.In order to evaluate the utility of C. sahuynhensis against influenza A virus (H5N1) and SARS-CoV-2, the composition of the essence is further subjected to more in-depth analysis using in silico approaches.

DFT-based quantum chemical properties
The quantum calculation retrievals are the energy-optimal geometries and electronic characteristics, which are utilized for argument on ab initio intermolecular interactability of the host molecule.It is noteworthy that this is the view from the intrinsic chemical properties of the potential ligands (1-27) without any reference to inhibited structures.The most stable structural geometries are shown in Figure 4. Overall, no explicit molecular constraints or abnormality are observed regarding the bonding angles and lengths.These unconstraint properties implicate the confirmation of the stable existence of natural products, thus validating the spectroscopic characterization and structural elucidation.In other words, for example, the calculated bonding lengths are within the range of characteristic ones, such as 1.2-1.4Å for C-O, ca.1.1 Å for C-H, and ca.1.3-1.5 Å for C-C; also, the aromatic ring is in planar.
Table 2 summarizes their corresponding molecular properties, including ground state energy and dipole moment.The former represents chemical inactivity, while the latter defines the positive-negative charge separation in a system.Their negative ground-state energy, especially 18−27 (under −900 a.u.), indicates electronic stability, thus unlikely sensitive to chemical reactions and likely conducive to non-chemical interactions, e.g.This means that although 27 is promising from the view of chemical inertia, the candidate is considered incompatible with a dipole-solvent environment, such as physio-chemical media.In the case of 2 (camphor), although it has favored dipole moment, its high ground energy means that the compound is likely to induce chemical reactions with the body, thus not recommended for applications as a bio-inhibitor.Therefore, the intrinsic quantum properties suggest the potential of 19 and 23−26 for biological applications in general and protein-inhibited interactions (based on van de Waals forces or ionic bonds [47]) in particular.
Figure 5 provides MEP maps over the molecular plane of each compound (1−27); this equals the distribution of chemical activities with color-coding scheme given in the figure caption.The visualization explicitly suggests the elevated flexibility of 23−27 when in a potential physical interaction with collided complex structures; the explanation can be argued based on their arbitrarily and consecutively shifting chemical tendencies over the molecular planes (observed by the rapid switch of color schemes).This would be conducive to inhibitory applications against complex structures, such as proteins.From this perspective, although possessing a rather simple molecular structure, 19 is ably performing flexibility to a certain degree.In contrast, the others (1−22) seem to be rather neutral in terms of electronic potential with a limited region for external interaction.
In summary, quantum analysis preliminarily specifies 23−26, and 19 as the most promising bio-inhibitors based on their intrinsic electronic properties.

Docking-based inhibitability
The inhibitory potential of each candidate toward specific protein structures is assessed by the docking technique.This considers their potentiality in the context of the static interactions between the ligands (1−27) and their targeted proteins related to Influenza (5E32) and SARS-CoV-2 (6LU7 and 7T9J).Following this scope, the primary parameters selected to evaluate the inhibitory effectiveness are the total DS values, i.e., the representative of pseudo-Gibbs free energy of inhibitory complex formation, and the hydrogen-like bonds, i.e. the representative of strong ligand-protein binding.In this discussion, the average DS value is reasoned as the representative indicator of a multi-site inhibitory process.In principle, a simultaneous inhibition is more likely to channel sufficient distortion forces onto the secondary-tertiary protein structures, which in turn induces the decreased efficacy of the enzymatic activities overall based on the mechanism of allosteric non-competitive inhibition.This approach is especially significant since the candidates are from natural sources with a diversity of structural elements and chemical characteristics.
For further reference, the in-detail data for each of the most effective inhibitory systems regarding each ligandprotein inhibition are provided in Supporting Information.The corresponding visualizations of in-site arrangements and interaction maps are presented in this report with a symbol-coding scheme given in the figure caption.

Protein 5E32
The sites of 5E32 with the highest vulnerability toward the ligands (1-27 and D1) are shown in Figure 6; meanwhile, the corresponding primary docking parameters are given in Table 3.In general, the testing compounds register different affinities toward the sites.The most effective inhibitors against 5E32 (influenza A HA) can be interpreted by the average DS values, ranked by the order: 23 ≈ 26 (DS average −10.1 kcal mol −1 ) > 15 ≈ D (DS average −9.6 kcal mol −1 ).These candidates are expected to perform equal-to-elevated efficacy compared to the commercialized drug oseltamivir in terms of the inhibitory mechanism.The average values are of importance as in-reality biological inhibition is a rather simultaneous process, i.e. multi-site inhibition, than a selective one against a specific site.Besides, 19 and 24 (DS average  −8.9 kcal mol −1 ) are also considerable.In contrast, although 25 and 27 are preceding suggested by their electronic properties (given by quantum analyses), in the context of ligand-5E32 inhibitability, they seem to be incompetent.If considering the most effective ones, the theoretical argument can also propose the ranking: 23-5E32 (DS −12.9 kcal mol −1 ) > D1-5E32 (DS −12.4 kcal mol −1 ) > 26-5E32 (DS −12.2 kcal mol −1 ) > 24-5E32 (DS −12.0 kcal mol −1 ) > 15-5E32 (DS −11.9 kcal mol −1 ); these can be thought of the main product of each ligand-protein inhibition.Figure 7 presents in-site arrangements and interactive maps of the most effective ligand-5E32 inhibitory system.Given 3D in-pose morphology, the ligands rather fit tightly into the sites.This means further modification/functionalization of extended size is not recommended for current inhibitors.Regarding 2D interaction mapping, the ligands   have good conformational fitness with the in-site features given by the continuousness of dashed contours.

Protein 6LU7
The sites of 6LU7 with the highest vulnerability towards the ligands (1-27 and D2) are shown in Figure 8; meanwhile, the corresponding primary docking parameters are given in Table 4. Overall, the protein structure seems to be more susceptible to external inhibition at sites 1 and 2. On average, the most effective inhibitors against 6LU7 (SARS-CoV-2 main protease) are predicted in the order: 26 (DS average −10.6 kcal mol −1 ) > D2 (DS average −9.7 kcal mol −1 ) > 23 (DS average −9.2 kcal mol −1 ) > 3 ≈ 25 (DS average ca.−9 kcal mol −1 ).Among these candidates, compound 26 is expected to perform elevated inhibitory ability, cf. the control drug; meanwhile, the others are still promising for further consideration.On the other hand, the corresponding figures for 19 and 24 (DS average ca.−8.5 kcal mol −1 ) can be considered yet not highly recommended; while 27 (DS average ca.−7.6 kcal mol −1 ) is rather incompetent, even though it is favored by certain quantum-based properties, i.e., ground energy and potential    distribution.If considering the most effective ones, the theoretical argument can also propose the ranking: 26-6LU7 (DS −12.4 kcal mol −1 ) > D2-6LU7 (DS −12.0 kcal mol −1 ) > 25-6LU7 ≈ 22-6LU7 (DS −11.9 kcal mol −1 ) > 23-6LU7 (DS −11.6 kcal mol −1 ).In this consideration, 26 seems to have a special affinity toward site 3 of the protein structure.Figure 9 presents in-site arrangements and interactive maps of the most effective ligand-6LU7 inhibitory system.First, 3D in-pose renderings reveal that the sites are still spacious after inhibited, thus implicating the potentiality of structural modification on the current ligands (if needed for compatible enhancement).Regarding 2D interaction mapping, the ligands are likely to have good conformational fitness with the in-site features given by the continuousness of dashed contours.

Protein 7T9J
The sites of 7T9J with the highest vulnerability toward the ligands (1-27 and D2) are shown in Figure 10; meanwhile, the corresponding primary docking parameters are given in Table 5.Overall, the protein structure is less selective for compatible inhibitors than that of the main protease.This might to some aspects explain the high transmission of Omicron variants by easily binding its spike proteins with external receptors.On average, the most effective inhibitors against 7T9J (Omicron-variant spike protein) are predicted in the order: 23 (DS average −10.7 kcal mol −1 ) > D2 (DS average −10.6 kcal mol −1 ) > 24 (DS average −10.3 kcal mol −1 ) > 26 ≈ 15 (DS average ca.−9.4 kcal mol −1 ).Again, 23, 24, and 26 are expected to be effective inhibitors against SARS-  ).This reinforces the potentiality of 23 as an inhibitor against 7T9J.Figure 11 presents in-site arrangements and interactive maps of the most effective ligand-7T9J inhibitory system.Given 3D in-pose morphology, the sites are observed rather close and tight in space.This means further modification/functionalization to the ligands is not recommended.Regarding 2D interaction mapping, the ligand-protein conformational fitness is seen at a high degree.This implies two opposite speculations: (i) it is difficult for the ligands to be placed inside the protein sites, yet (ii) the spatial bound might be conducive to the duration of effectiveness as the compounds are likely to be confined in the pose longer.
In summary, the results from the docking technique can only provide an early view of the static interactions between the candidates and their targeted proteins (at different sites).In order to validate the structure-denaturation aftereffects, molecular dynamics simulation can be used to directly monitor the motion/displacement of catalytic residues or experimental enzymatic bioassays can be carried out to examine the overall inhibitory efficacy.

Figure 5 :
Figure 5: MEP formed by mapping of total density over the electrostatic potential of 1−27 using DFT at the level of theory M052X/def2-TZVPP; reddish region: negative electrostatic potential, bluish region: positive electrostatic potential, greenish region: null electrostatic potential.

Table 2 :
Ground state electronic energy and dipole moment value of 1−27 by DFT at the level of theory M052X/6-311++g(d,p)

Table 3 :
Primary docking results on inhibitability of ligand-5E32 complexes P: protein; L: ligand; E: DS value (kcal mol −1 ); N: number of hydrophilic interactions.*Most effective ligand-protein complexes (in-detail data provided in Supporting Information).

Table 4 :
Primary docking results on inhibitability of ligand-6LU7 complexes P: protein; L: ligand; E: DS value (kcal mol −1 ); N: number of hydrophilic interactions.*Most effective ligand−protein complexes (in-detail data provided in Supporting Information).

Table 5 :
Primary docking results on inhibitability of ligand−7T9J complexes

Table 9 :
ADMET-based pharmacokinetics and pharmacology of 19−27 and D1−D2 log mM.system.Regarding absorption, 23 has no significant interaction with P-glycoprotein, thus no effects on the extrusion of the toxins and xenobiotics out of cells, while 26 is predicted otherwise.Both can be absorbed easily via intestinal routine (>95%).In general, C. sahuynhensis essence is a safe source of natural products for humans; in particular, 23 and 26 express high suitability for further drug-like development.This is the first computer-based effort to screen for the antiviral potentiality of C. sahuynhensis n-hexane fraction (1−27), particularly against H5 HA in influenza A virus (PDB-5E32), wild-variant SARS-CoV-2 main protease (PDB-6LU7), and SARS-CoV-2 Omicron spike protein (PDB-7T9J).A combination of computational platforms specifies the most promising bio-inhibitors based on theoretical arguments from quantum calculations, docking simulations, and QSARbased analyses, i.e., 23 (bio-compatibility: ground energy −966.73 a.u., dipole moment 3.708 Debye; bio-inhibitability: DS ̅ −12.5 kcal mol −1 ; drug-likeness: mass 304.7 amu, log P 1.31; polar-interactability: polarizability 32.8 Å 3 ) and 26 (bio-compatibility: ground energy −1393.66109a.u., dipole moment 5.087 Debye; bio-inhibitability: DS ̅ −11.9 kcal mol −1 ; drug-like- ness: mass 437.5 amu, log P 4.28; polar-interactability: polarizability 45.7 Å 3 ).The compounds also have favorable pharmacokinetics and pharmacology (based on the pkCSM-ADMET model).The total essence is ineffective for use as an antiviral source in its pure form since the most promising candidates account for minor proportions.Altogether, the results from this theoretical study encourage further isolation and preclinical tests for antiviral activities on 23 (7β-hydroxydehydroepiandrosterone) and 26 (ethyl cholate).