Unveiling the Antiviral Efficacy of Forskolin: A Multifaceted In Vitro and In Silico Approach.

Coleus forskohlii (Willd.) Briq. is a medicinal herb of the Lamiaceae family. It is native to India and widely present in the tropical and sub-tropical regions of Egypt, China, Ethiopia, and Pakistan. The roots of C. forskohlii are edible, rich with pharmaceutically bioactive compounds, and traditionally reported to treat a variety of diseases, including inflammation, respiratory disorders, obesity, and viral ailments. Notably, the emergence of viral diseases is expected to quickly spread; consequently, these data impose a need for various approaches to develop broad active therapeutics for utilization in the management of future viral infectious outbreaks. In this study, the naturally occurring labdane diterpenoid derivative, Forskolin, was obtained from Coleus forskohlii. Additionally, we evaluated the antiviral potential of Forskolin towards three viruses, namely the herpes simplex viruses 1 and 2 (HSV-1 and HSV-2), hepatitis A virus (HAV), and coxsackievirus B4 (COX-B4). We observed that Forskolin displayed antiviral activity against HAV, COX-B4, HSV-1, and HSV-2 with IC50 values of 62.9, 73.1, 99.0, and 106.0 µg/mL, respectively. Furthermore, we explored the Forskolin's potential antiviral target using PharmMapper, a pharmacophore-based virtual screening platform. Forskolin's modeled structure was analyzed to identify potential protein targets linked to its antiviral activity, with results ranked based on Fit scores. Cathepsin L (PDB ID: 3BC3) emerged as a top-scoring hit, prompting further exploration through molecular docking and MD simulations. Our analysis revealed that Forskolin's binding mode within Cathepsin L's active site, characterized by stable hydrogen bonding and hydrophobic interactions, mirrors that of a co-crystallized inhibitor. These findings, supported by consistent RMSD profiles and similar binding free energies, suggest Forskolin's potential in inhibiting Cathepsin L, highlighting its promise as an antiviral agent.

Nanoemulsions of Jasminum humile L. and Jasminum grandiflorum L. Essential Oils: An Approach to Enhance Their Cytotoxic and Antiviral Effects.

Unprecedented nanoemulsion formulations (NE) of Jasminum humile and Jasminum grandiflorum essential oils (EO) were prepared, and examined for their cytotoxic and antiviral activities. NE characterization and stability examination tests were performed to ensure formula stability. The antiviral activity was determined against hepatitis A (HAV) and herpes simplex type-1 (HSV-1) viruses using MTT assay, while the cytotoxic potential was determined against liver (HepG-2), breast (MCF-7), leukemia (THP-1) cancer cell lines and normal Vero cells. Statistical significance was determined in comparison with doxorubicin as cytotoxic and acyclovir as antiviral standard drugs. GC-MS analysis indicated twenty four compounds in the EO of J. humile and seventeen compounds in the EO of J. grandiflorum. Biological investigations of pure EOs revealed weak cytotoxic and antiviral effects. Nevertheless, their NE formulations exhibited high biological value as cytotoxic and antiviral agents. NE formulations also showed feasible selectivity index for the viral-infected and cancer cells (especially HepG-2) than normal Vero cells. Both nanoemulsions showed lower IC50 than standard doxorubicin against HepG-2 (26.65 and 22.58 vs. 33.96 µg/mL) and MCF-7 (36.09 and 36.19 vs. 52.73 µg/mL), respectively. The study results showed the dramatic effect of nanoemulsion preparation on the biological activity of EOs and other liposoluble phytopharmaceuticals.

Natural Products and Their Potential Anti-HAV Activity.

The role of purified natural products in the prevention and treatment of countless diseases of bacterial, fungal, and viral origin cannot be overestimated. New antiviral drugs have been obtained from natural sources and transformed into preparations for prophylactic and therapeutic purposes. Flavonoids, polyphenols, saponins, proanthocyanins, polysaccharides, organic acids, proteins, polypeptides, and essential oils derived from plants, animals, or microorganisms can control and combat foodborne viral infections, including hepatitis A. The components of essential oils are characterized by numerous therapeutic and antioxidant properties and exhibit a broad spectrum of antimicrobial and antiviral activity. Due to these properties, they can be used to preserve meat, fruit, vegetables, and their products. Over the past two decades, much effort has been made to identify natural products, mostly of plant origin, to combat foodborne viruses. Natural plant extracts have several potential uses, not limited to increasing the safety of food products and improving their quality, but also as natural antiviral agents.

Antiviral activity of castor oil plant (Ricinus communis) leaf extracts.

ETHNOPHARMACOLOGICAL RELEVANCE: Ricinus communis L., commonly known as castor oil plant, is a precious traditional medicine with a history of thousands of years in the world. Castor oil plant has high traditional and medicinal values for treating liver infections, stomach ache, flatulence, constipation, inflammation, warts, colic, enteritis, fever, headache, and as a counter irritant. Its diverse phytochemicals have a wide range of valuable medicinal activities including hepatoprotective, anti-nociceptive, antioxidant, antiulcer, anticancer, anti-inflammatory, central analgesic, antidiabetic, antimicrobial, antiviral, and wound healing activity. AIM OF THE WORK: To provide a complete characterization of the composition of Ricinus communis leaves using ultra-performance liquid chromatography coupled with hybrid triple time-of-flight mass spectrometry (UPLC-Triple TOF-MS/MS) and different chromatographic techniques and to evaluate its antiviral potential using three mechanisms against three common viruses. MATERIALS AND METHODS: R. communis leaves were extracted with 70% methanol and further partitioned with solvents of increasing polarities: petroleum ether, dichloromethane (CH2Cl2), ethyl acetate, and n-butanol. The CH2Cl2 and n-butanol fractions were subjected to repeated chromatographic separation to isolate the phytochemicals, and their structures were elucidated using nuclear magnetic resonance spectroscopy. UPLC-Triple TOF-MS/MS was performed to determine the different phytochemicals in the ethyl acetate fraction. The antiviral activity of the extracts was investigated using the maximum nontoxic concentration of each against the challenge dose of the virus (CDV) and 1/10 and 1/100 dilutions of the CDV for Coxsackie B virus type 4 (COXB4), herpes simplex virus type 1 (HSV1), and hepatitis A virus (HAV) using Vero cell cultures that were treated according to three protocols to test for anti-replicative, protective, and anti-infective antiviral activity. Cell viability was evaluated using the MTT colorimetric assay and each experiment is repeated three times independently of each other. RESULTS: R. communis leaves possessed antiviral activity. Evaluation of the anti-replicative activity showed that all extracts possessed high anti-replicative activity against HAV especially methanol and methylene chloride fractions and moderate activity against COXB4; butanol > methylene chloride and ethyl acetate > methanol. All extracts showed protective activity against HAV, especially butanol extract, while methanol extracts showed higher non-significant antiviral protective activity against HSV1 vs Acyclovir. Almost no anti-infective effects were recorded for any extract against the studied viruses. CONCLUSION: The discriminatory effect against each virus by different mechanisms suggests the presence of different chemical compounds. The alkaloid and phenolic derivatives of the extracts of R. communis leaves may help develop a drug to prevent or treat common viral infections. Further investigations are recommended to define the bioactive antiviral properties of R. communis leaves.

Cell Culture Systems and Drug Targets for Hepatitis A Virus Infection.

Hepatitis A virus (HAV) infection is one of the major causes of acute hepatitis, and this infection occasionally causes acute liver failure. HAV infection is associated with HAV-contaminated food and water as well as sexual transmission among men who have sex with men. Although an HAV vaccine has been developed, outbreaks of hepatitis A and life-threatening severe HAV infections are still observed worldwide. Therefore, an improved HAV vaccine and anti-HAV drugs for severe hepatitis A should be developed. Here, we reviewed cell culture systems for HAV infection, and other issues. This review may help with improving the HAV vaccine and developing anti-HAV drugs.

Superinfection of hepatitis A virus in hepatocytes infected with hepatitis B virus.

Hepatitis A virus (HAV) infection is a major cause of acute hepatitis including acute liver failure. Hepatitis B infection (HBV) occurs worldwide, with the highest rates in Asian and African countries, and there are several reports that HAV infection may have a more severe clinical course in patients with chronic HBV infection. We previously demonstrated that Japanese miso extracts have inhibitory effects on HAV replication. In the present study, we examined the replication of HAV and HBV in a hepatocyte superinfection model and the inhibitory effects of Japanese miso extracts on both viruses. According to the results, HAV infection inhibited HBV replication in superinfected hepatocytes, and Japanese rice-koji miso extracts had inhibitory effects on HAV replication. Our findings provide useful information for clinicians in managing HAV infection in patients with chronic HBV infection.

Inhibitory effect of Japanese rice-koji miso extracts on hepatitis A virus replication in association with the elevation of glucose-regulated protein 78 expression.

Hepatitis A virus (HAV) infection is one of the major causes of acute hepatitis and acute liver failure in developing and developed countries. Although effective vaccines for HAV infection are available, outbreaks of HAV infection still cause deaths, even in developed countries. One approach to control HAV infection is prevention through diet, which can inhibit HAV propagation and replication. Glucose-regulated protein 78 (GRP78) is a member of the heat shock protein 70 family of molecular chaperone required for endoplasmic reticulum stress and stress-induced autophagy. We previously showed that the elevation of GRP78 expression inhibits HAV replication. It has been reported that Japanese miso extracts, which was made from rice-koji, enhance GRP78 expression. In the present study, we used human hepatoma Huh7 cells and human hepatocyte PXB cells to examine the efficacy of Japanese miso extracts as antiviral agents against HAV. Japanese miso extracts enhanced GRP78 expression and inhibited HAV replication in human hepatocytes. Together, these results demonstrate that Japanese miso extracts may partly modulate GRP78 expression and additively or synergistically work as antivirals against HAV infection. Japanese miso extracts can be used as effective dietary supplements for severe hepatitis A.

Aqueous Extracts of Hibiscus sabdariffa Calyces Decrease Hepatitis A Virus and Human Norovirus Surrogate Titers.

Hibiscus sabdariffa extract is known to have antioxidant, anti-diabetic, and antimicrobial properties. However, their effects against foodborne viruses are currently unknown. The objective of this study was to determine the antiviral effects of aqueous extracts of H. sabdariffa against human norovirus surrogates (feline calicivirus (FCV-F9) and murine norovirus (MNV-1)) and hepatitis A virus (HAV) at 37 °C over 24 h. Individual viruses (~5 log PFU/ml) were incubated with 40 or 100 mg/ml of aqueous hibiscus extract (HE; pH 3.6), protocatechuic acid (PCA; 3 or 6 mg/ml, pH 3.6), ferulic acid (FA; 0.5 or 1 mg/ml; pH 4.0), malic acid (10 mM; pH 3.0), or phosphate buffered saline (pH 7.2 as control) at 37 °C over 24 h. Each treatment was replicated thrice and plaque assayed in duplicate. FCV-F9 titers were reduced to undetectable levels after 15 min with both 40 and 100 mg/ml HE. MNV-1 was reduced by 1.77 ± 0.10 and 1.88 ± 0.12 log PFU/ml after 6 h with 40 and 100 mg/ml HE, respectively, and to undetectable levels after 24 h by both concentrations. HAV was reduced to undetectable levels by both HE concentrations after 24 h. PCA at 3 mg/ml reduced FCV-F9 titers to undetectable levels after 6 h, MNV-1 by 0.53 ± 0.01 log PFU/ml after 6 h, and caused no significant change in HAV titers. FA reduced FCV-F9 to undetectable levels after 3 h and MNV-1 and HAV after 24 h. Transmission electron microscopy showed no conclusive results. The findings suggest that H. sabdariffa extracts have potential to prevent foodborne viral transmission.