Antiviral activities of Clinacanthus nutans (Burm.f.) Lindau extract against Cyprinid herpesvirus 3 in koi (Cyprinus carpio koi)

Kaempferol is a novel antiviral agent against channel catfish virus infection through blocking viral attachment and penetration in vitro

Channel catfish virus (CCV, Ictalurid herpesvirus 1) is the causative pathogen of channel catfish virus disease, which has caused high mortality and substantial economic losses in the catfish aquaculture industry. Due to the lack of licensed prophylactic vaccines and therapeutic drugs, the prevention and control of CCV infection seem to remain stagnant. Active compounds from medicinal plants offer eligible sources of pharmaceuticals and lead drugs to fight against endemic and pandemic diseases and exhibit excellent effect against viral infection. In this study, we evaluated the antiviral ability of 12 natural compounds against CCV with cell models in vitro and found kaempferol exhibited the strongest inhibitory compound against CCV infection among all the tested compounds. Correspondingly, kaempferol decreased transcription levels of viral genes and the synthesis of viral proteins, as well as reduced proliferation and release of viral progeny, the severity of the CPE induced by CCV in a dose-dependent manner, based on quantitative real-time PCR (RT-qPCR), western blotting, viral cytopathic effects (CPE) and viral titer assessment. Moreover, time-of-drug-addition assays, virus attachment, and penetration assays revealed that kaempferol exerted anti-CCV activity probably by blocking attachment and internalization of the viral entry process. Altogether, the present results indicated that kaempferol may be a promising candidate antiviral agent against CCV infection, which shed light on the development of a novel and potent treatment for fish herpesvirus infection.

An update about beneficial effects of medicinal plants in aquaculture: A review

Aquaculture is an essential and growing component of agricultural and global ecosystems worldwide. Aquaculture provides more than 25% of the total aquatic food consumption by humans. The development of the aquaculture industry should be followed in successive industrial years, and therefore it is necessary to pay attention to the management and type of farming system that is compatible with the environment. The use of antibiotics for disease control has been criticised for their negative effects, including the emergence of antibiotic-resistant bacteria, the suppression of the immune system and the environment, and the accumulation of residue in aquatic tissues. The use of these products reduces the need for treatments, enhances the effect of vaccines, and, in turn, improves production indicators. Medicinal plants have increasingly been used in recent years as a disease control strategy in aquaculture, boosting the immune system of aquatic animals and helping to develop strong resistance to a wide range of pathogens. Therefore, this review aims to provide an overview of the recent evidence on the beneficial use of medicinal plants to promote growth and strengthen the immune system in farmed aquatic animals.

Antiviral and Immunomodulatory Activities of Clinacanthus nutans (Burm. f.) Lindau

Clinacanthus nutans (Burm. f.) Lindau has been used as a traditional herbal medicine for treating snake bites, scalds, burns, and viral and bacterial infections. It has been attracting an increasing amount of attention because of its biological activities, including its antidiabetic, antioxidant, antibacterial, anticancer, anti-inflammatory, antiviral, and immunoregulatory activities. Here, we conducted a panoramic survey of the literature regarding the immunoregulatory, anti-inflammatory, and antiviral activities of C. nutans. We discovered that C. nutans extracts have virucidal activities against herpes simplex virus types 1 and 2, varicella-zoster virus, cyprinid herpesvirus 3, porcine reproductive and respiratory syndrome virus, mosquito-borne chikungunya virus, and potentially SARS-CoV-2; such activities likely result from C. nutans interfering with the entry, penetration, infection, and replication of viruses. We also reviewed the phytochemicals in C. nutans extracts that exhibit anti-inflammatory and immunoregulatory activities. This updated review of the antiviral, anti-inflammatory, and immunoregulatory activities of C. nutans may guide future agricultural practices and reveal clinical applications of C. nutans.

Anthocyanins in Red Jasmine Rice (Oryza sativa L.) Extracts and Efficacy on Inhibition of Herpes Simplex Virus, Free Radicals and Cancer Cell

Rice is one of the most important food crops in many countries, with nutritional value and health benefits. In this study, the ethanolic and aqueous extracts of red jasmine rice from Chiang Mai, Thailand were examined for their anthocyanins and phenolic contents. The antioxidant and antiviral activity against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), as well as anticancer activity, were investigated. The total anthocyanins content of 708.03 ± 11.56 mg Cy-3-glc equivalent/g extract, determined from the ethanolic extract, was higher than the aqueous extract. However, the aqueous extract showed the highest total phenolic compound of 81.91 ± 0.51 mg GAE/g extract. In addition, the ethanolic extract demonstrated higher antioxidant activity than aqueous extract using DPPH, ABTS, and FRAP assays by 28.91 ± 3.26 mg GAE/g extract, 189.45 ± 11.58 mg 24 TEAC/g extract, and 3292.46 ± 259.64 g FeSO₄/g extract, respectively. In the antiviral assay, it was found that the ethanolic extract of red jasmine rice could inhibit HSV-1 more effectively than HSV-2 when treated before, during, and after the viral attachment on Vero cells, with 50% effective doses of 227.53 ± 2.41, 189.59 ± 7.76, and 192.62 ± 2.40 µg/mL, respectively. The extract also demonstrated the highest reduction of HSV-1 particles at 4 h after treatment and the inhibition of HSV-1 replication. The ethanolic extract exhibited a higher toxicity level than the aqueous extract, as well as the potential to induce DNA fragmentation by intrinsic and extrinsic apoptosis pathways on the Caco-2 cells. These findings suggest that red jasmine rice extract demonstrates nutritional value and biological activity on HSV, free radicals, and cancer cell inhibition.

Ophiopogon japonicus inhibits white spot syndrome virus proliferation in vivo and enhances immune response in Chinese mitten crab Eriocheir sinensis

White spot syndrome virus (WSSV) is a fatal pathogen threatening global crustacean industry with no commercially available drugs to control. Herbal medicines have been widely used to treat a number of viral infections, which could offer a rich reserve for antiviral drug discovery. Here, we evaluated the inhibition activities of 30 herbal medicines against WSSV in Chinese mitten crab Eriocheir sinensis. A WSSV infection model in E. sinensis was firstly established in order to determine the antiviral effects of the plant extracts and to explore the potential action mechanisms. Results showed that the highest anti-WSSV activity was obtained by the treatment of Ophiopogon japonicus extract (93.03%, 100 mg/kg). O. japonicus treatment decreased viral loads in a dose-dependent manner and significantly improved the survival of WSSV-challenged crabs. O. japonicus reduced the expression of vital genes in viral life cycle in vivo, particularly for the immediate-early stage gene ie1. Further results indicated that O. japonicus could repress the JAK-STAT signaling pathway to block ie1 transcription. Moreover, O. japonicus could modulate certain immune genes such as the myosin, toll-like receptor, crustin, and prophenoloxidase in the interactions between WSSV and crabs. The up-regulated expression of pro-autophagic factors (Gabarap and Atg7) and elevated levels of antioxidant enzymes (SOD, CAT and GSH) suggested that O. japonicus may induce autophagy and attenuate WSSV-induced oxidative stress. Taken together, O. japonicus could inhibit WSSV proliferation and improve the survival of WSSV-challenged crabs. Thus, O. japonicus may have the potential to be developed as a preventive or therapeutic agent against WSSV, and its effective compounds merit further isolation and identification.

Inhibitory properties of crude microalgal extracts on the in vitro replication of cyprinid herpesvirus 3

Microalgae are possible sources of antiviral substances, e.g. against cyprinid herpesvirus 3 (CyHV-3). Although this virus leads to high mortalities in aquacultures, there is no treatment available yet. Hence, ethanolic extracts produced with accelerated solvent extraction from six microalgal species (Arthrospira platensis, Chlamydomonas reinhardtii, Chlorella kessleri, Haematococcus pluvialis, Nostoc punctiforme and Scenedesmus obliquus) were examined in this study. An inhibition of the in vitro replication of CyHV-3 could be confirmed for all six species, with the greatest effect for the C. reinhardtii and H. pluvialis crude extracts. At still non-cytotoxic concentrations, viral DNA replication was reduced by over 3 orders of magnitude each compared to the untreated replication controls, while the virus titers were even below the limit of detection (reduction of 4 orders of magnitude). When pre-incubating both cells and virus with C. reinhardtii and H. pluvialis extracts before inoculation, the reduction of viral DNA was even stronger (> 4 orders of magnitude) and no infectious viral particles were detected. Thus, the results of this study indicate that microalgae and cyanobacteria are a promising source of natural bioactive substances against CyHV-3. However, further studies regarding the isolation and identification of the active components of the extracts are needed.

Evaluation of the antiviral activity of naringenin, a major constituent of Typha angustifolia, against white spot syndrome virus in crayfish Procambarus clarkii

White spot syndrome virus (WSSV) is a serious pathogen threatening global crustacean aquaculture with no commercially available drugs. Herbal medicines widely used in antiviral research offer a rich reserve for drug discovery. Here, we investigated the inhibitory activity of 13 herbal medicines against WSSV in crayfish Procambarus clarkii and discovered that naringenin (NAR) has potent anti-WSSV activity. In the preliminary screening, the extracts of Typha angustifolia displayed the highest inhibitory activity on WSSV replication (84.62%, 100 mg/kg). Further, NAR, the main active compound of T. angustifolia, showed a much higher inhibition rate (92.85%, 50 mg/kg). NAR repressed WSSV proliferation followed a dose-dependent manner and significantly improved the survival of WSSV-challenged crayfish. Moreover, pre- or post-treatment of NAR displayed a comparable inhibition on the viral loads. NAR decreased the transcriptional levels of vital genes in viral life cycle, particularly for the immediately early-stage gene ie1. Further results showed that NAR could decrease the STAT gene expression to block ie1 transcription. Besides, NAR modulated immune-related gene Hsp70, antioxidant (cMnSOD, mMnSOD, CAT, GST), anti-inflammatory (COX-1, COX-2) and pro-apoptosis-related factors (Bax and BI-1) to inhibit WSSV replication. Overall, these results suggest that NAR may have the potential to be developed as preventive or therapeutic agent against WSSV.

Antiviral medicinal plants found in Lanna traditional medicine

Traditional medicine uses a multitude of plants to create medicinal formulations, some of which show antiviral properties that may be of benefit in treating emerging viral diseases, including Covid-19. Lanna, an ancient Kingdom in Northern Thailand, with a thriving culture that continues to this day and has a rich history of traditional medicine using local plants that is still practiced today. To find potential antiviral medicinal candidates, we examined ancient manuscripts, interviewed traditional healers practicing today, and inventoried current traditional medicines to catalogue 1400 medicinal formulations used in Lanna traditional medicine. We then narrowed this list to find those traditionally used to treat diseases that in their original use and descriptions most likely map to those we know today to be viral diseases. We identified the plants used in these formulations to create a list of 64 potential antiviral herbal candidates drawn from this ancient Lanna wisdom and matched these to the scientific literature to see which of these plants had already been shown to possess antiviral properties, generating a list of 64 potential antiviral medicinal candidates from Lanna traditional medicine worth further investigation for treating emerging viral diseases.

Suppression effect of plant-derived berberine on cyprinid herpesvirus 2 proliferation and its pharmacokinetics in Crucian carp (Carassius auratus gibelio)

Cyprinid herpesvirus 2 (CyHV-2), which infects silver crucian carp including goldfish (Carassius auratus auratus) and Crucian carp (Carassius auratus gibelio) with high mortality, is an emerging viral pathogen worldwide. Previous studies showed that berberine (BBR), a bioactive plant-derived alkaloid, demonstrated potential antiviral actions against many different viruses. Here, we assessed the effect of berberine hydrochloride (BBH) on the replication of CyHV-2 in vitro and in vivo. Cytotoxicity assay indicated that 5-25 μg/mL BBH was non-toxic to the RyuF-2 cells. In viral inhibition assays, real time PCR was employed to titrate the genomic copy number of progeny virus, real time RT-PCR was applied to monitor the transcriptional levels of viral genes, and Western blot analysis was performed to detect the synthetic levels of viral proteins. The results demonstrated that BBH systematically impedes the viral gene transcription and suppressed the replication of CyHV-2 in RyuF-2 cells. In animal challenge test, BBH was confirmed to protect Crucian carps from CyHV-2 infection in a dose-dependent manner, which was supported by suppressed viral replication levels, reduced viral pathogenesis and higher survival rates. Furthermore, pharmacokinetics data of BBH in Crucian carp revealed its rapid absorption (T_max of 1.5 h), suitable plasma half-life (t_1/2z/h of 7-12 h depending on oral dosage), and dose-dependent drug exposure properties following oral administration (revealed by AUC_0-t values). These findings shed light on repurposing BBH to treat CyHV-2 infections in silver crucian carp.

Pharmacokinetic and Efficacy Study of Acyclovir Against Cyprinid Herpesvirus 3 in Cyprinus carpio

Cyprinid Herpesvirus 3 (CyHV-3), more commonly known as Koi Herpesvirus (KHV), is a re-emergent virus causing acute systemic infection with high mortality rates in koi fish (Cyprinus carpio). Survivors from outbreaks can become latent carriers, with viral reactivation under stressful conditions and permissible temperatures. No vaccines or treatments are currently available in the United States. Acyclovir has been shown effective in vitro against KHV. This study aimed to evaluate the cytotoxicity of acyclovir and cidofovir to koi fin (KF1) cells, the efficacy of a single antiviral intracoelomic dose in a koi fingerling cohabitation challenge, and the pharmacokinetics of the effective antiviral. Initially, a lactate dehydrogenase release-based assay revealed no significant acyclovir or cidofovir cytotoxicity to KF1 cells for 24 h at up to 1,500 μM. In laboratory-controlled challenges, KHV associated mortalities occurred 2 weeks post-infection. At this point, fish were treated with an antiviral (10 mg/kg acyclovir or 5 mg/kg cidofovir) or sterile phosphate-buffered solution. Morbidity and mortality were monitored for 30 days. A significant cumulative mortality reduction (p ≤ 0.05), and a 3-day mortality delay were detected in the acyclovir-treated group. Similar viral loads were detected in gills recovered from mortalities throughout the challenge and surviving fish at the end of the challenge regardless of treatment. For pharmacokinetic analysis, blood was collected at various timepoints after acyclovir administration. Liquid chromatography tandem mass spectrometry plasma analysis indicated a 141 μM peak plasma concentration at 0.75 h, a 14 h half-life, and a 0.05/h elimination rate constant. Histopathology of target tissues detected no evidence of acyclovir toxicity. Results suggest that a single 10 mg/kg dose of acyclovir administered intracoelomically to koi fingerlings is safe and reduces cumulative mortality during a KHV mortality event. However, multiple doses are probably required for effective treatment of pet fish.

Antiviral Medicinal Plants of Veterinary Importance: A Literature Review

Viruses have a high mutation rate, and, thus, there is a continual emergence of new antiviral-resistant strains. Therefore, it becomes imperative to explore and develop new antiviral compounds continually. The search for pharmacological substances of plant origin that are effective against animal viruses, which have a high mortality rate or cause large economic losses, has garnered interest in the last few decades. This systematic review compiles 130 plant species that exhibit antiviral activity on 37 different virus species causing serious diseases in animals. The kind of extract, fraction, or compound exhibiting the antiviral activity and the design of the trial were particularly considered for review. The literature revealed details regarding plant species exhibiting antiviral activities against pathogenic animal virus species of the following families-Herpesviridae, Orthomyxoviridae, Paramyxoviridae, Parvoviridae, Poxviridae, Nimaviridae, Coronaviridae, Reoviridae, and Rhabdoviridae-that cause infections, among others, in poultry, cattle, pigs, horses, shrimps, and fish. Overall, 30 plant species exhibited activity against various influenza viruses, most of them causing avian influenza. Furthermore, 30 plant species were noted to be active against Newcastle disease virus. In addition, regarding the pathogens most frequently investigated, this review provides a compilation of 20 plant species active against bovine herpesvirus, 16 against fowlpox virus, 12 against white spot syndrome virus in marine shrimps, and 10 against suide herpesvirus. Nevertheless, some plant extracts, particularly their compounds, are promising candidates for the development of new antiviral remedies, which are urgently required.

In vitro screening antiviral activity of Thai medicinal plants against porcine reproductive and respiratory syndrome virus

BACKGROUND

Porcine reproductive and respiratory syndrome (PRRS) caused by PRRS virus (PRRSV) results in economic losses in the swine industry globally. Several studies have investigated the use of plant extracts in the prevention and control of PRRS outbreaks. Thai medicinal plants may be useful for treating PRRSV infection in pigs. Therefore, we investigated the in vitro anti-PRRSV and antioxidant properties of seven Thai medicinal plants: Caesalpinia sappan Linn., Garcinia mangostana Linn., Houttuynia cordata, Perilla frutescens, Clinacanthus nutans, Phyllanthus emblica, and Tiliacora triandra.

RESULTS

Using antiviral screening, we observed that T. triandra extract strongly inhibited PRRSV infectivity in MARC-145 cells [virus titer 3.5 median tissue culture infective dose (TCID₅₀)/ml (log10)] at 24 h post-infection, whereas C. sappan extract strongly inhibited PRRSV replication [virus titer 2.5 TCID₅₀/ml (log10)] at 72 h post-infection. C. sappan extract had the highest total phenolic content [220.52 mM gallic acid equivalent/g] and lowest half-maximal inhibitory concentration [1.17 mg/ml in 2,2-diphenyl-1-picrylhydrazyl and 2.58 mg/ml in 2,2-azino-bis (3-ethylbenzothiazo-line-6-sulfonic acid) diammonium salt].

CONCLUSION

T. triandra extract could inhibit PRRSV infectivity, whereas C. sappan extract was the most effective in inhibiting PRRSV replication in MARC-145 cells. This study elucidates the antiviral activities of Thai medicinal plant extracts in vivo. The results promise that Thai medicinal plant extracts, particularly T. triandra and C. sappan extracts, can be developed into pharmaceutical drugs for the prevention of PRRS in pigs.

Antitumor and antioxidant effects of Clinacanthus nutans Lindau in 4 T1 tumor-bearing mice

Background

Clinacanthus nutans Lindau (C. nutans) is a species of in Acanthaceae family and primarily used in South East Asian countries. C. nutans is well known as Sabah snake grass in Malaysia, and its leaves have diverse medicinal potential in conventional applications, including cancer treatments. On the basis of literature search, there is less conclusive evidence of the involvement of phytochemical constituents in breast cancer, in particular, animal tumor models. The current study aimed to determine the antitumor and antioxidant activities of C. nutans extract in 4 T1 tumor-bearing mice.

Methods

C. nutans leaves were subjected to methanol extraction and divided into two different concentrations, 200 mg/kg (low-dose) and 1000 mg/kg (high-dose). The antitumor effects of C. nutans extracts were assessed using bone marrow smearing, clonogenic, and splenocyte immunotype analyses. In addition, hematoxylin and eosin, tumor weight and tumor volume profiles also used to indicate apoptosis appearance. Serum cytokine levels were examined using ELISA assay. In addition, nitric oxide assay reflecting antioxidant activity was performed.

Results

From the results obtained, the methanol extract of C. nutans leaves at 200 mg/kg (P < 0.05) and 1000 mg/kg (P < 0.05) showed a significant decrease in nitric oxide (NO) and malondialdehyde (MDA) levels in the blood. On the other hand, C. nutans extract (1000 mg/kg) also showed a significant decrease in the number of mitotic cells, tumor weight, and tumor volume. No inflammatory and adverse reactions related to splenocytes activities were found in all treated groups of mice. Despite its promising results, the concentration of both C. nutans extracts have also reduced the number of colonies formed in the liver and lungs.

Conclusion

In conclusion, C. nutans extracts exert antitumor and antioxidant activities against 4 T1 mouse breast model with no adverse effect and inflammatory response at high dose of 1000 mg/kg, indicating an effective and complementary approach for cancer prevention and treatment.

Anti-CyHV-3 Effect of Fluorescent, Tricyclic Derivative of Acyclovir 6-(4-MeOPh)-TACV in vitro

Introduction

Cyprinid herpesvirus 3 (CyHV-3) is a virus infecting carp with disease symptoms of gill necrosis, fish discoloration, sunken eyes, and mortality reaching 90%. Several research groups have examined how to potentially abate the consequences of viral activity. Recently we showed that acyclovir inhibits CyHV-3 replication in vitro and in the present study we examined the anti-CyHV-3 activity of the tricyclic derivative of acyclovir 6-(4-MeOPh)-TACV (T-ACV), a fluorescent molecule known for higher lipophilicity than acyclovir, and therefore potentially better candidate for application in vivo.

Material and Methods

CCB and KF1 cell lines were incubated with T-ACV at concentrations of 0, 66.67, and 133.33 μM for three days and toxicity examined with MTT and CV assays. To investigate the antiviral activity of T-ACV, the lines were infected with CyHV-3 or mock infected and incubated for three days with the drug at concentrations of 0 or 66.67 μM. The activity of T-ACV was evaluated by plaque assay and TaqMan qPCR.

Results

T-ACV at a concentration of 66.67 μM displayed low toxicity and inhibited CyHV-3 activity by 13–29%, varying by cell line and method.

Conclusion

The low anti-CyHV-3 activity of T-ACV indicates that it would be reasonable to screen several tricyclic derivatives of acyclovir for such activity.

Evaluation of anti-proliferative activity of medicinal plants used in Asian Traditional Medicine to treat cancer

ETHNOPHARMACOLOGICAL RELEVANCE

The extensive biodiversity of plants in Southeast Asia and inadequate research hitherto warrant a continued investigation into medicinal plants. On the basis of a careful review of fresh medicinal plant usage to treat cancer from previous ethnobotanical interviews in Singapore and from the traditional uses of the indigenous plants, fresh leaves of seven locally grown medicinal plant species were evaluated for anti-proliferative activity.

AIM OF THE STUDY

To evaluate the anti-proliferative activity of local medicinal plant species Clausena lansium Skeels, Clinacanthus nutans (Burm. f.) Lindau, Leea indica (Burm. f.) Merr., Pereskia bleo (Kunth) DC., Strobilanthes crispus (L.) Blume, Vernonia amygdalina Delile and Vitex trifolia L.

MATERIALS AND METHOD

Fresh, healthy and mature leaves of the seven medicinal plants were harvested from various locations in Singapore and Malaysia for Soxhlet, ultrasonication and maceration extractions in three different solvents (water, ethanol and methanol). Cell proliferation assay using water soluble tetrazolium salt (WST-1) assay was performed on twelve human cancer cell lines derived from breast (MDA-MB-231, T47D), cervical (C33A), colon (HCT116), leukemia (U937), liver (HepG2, SNU-182, SNU-449), ovarian (OVCAR-5, PA-1, SK-OV-3) and uterine (MES-SA/DX5) cancer.

RESULTS

A total of 37 fresh leaf extracts from seven medicinal plants were evaluated for their anti-tumour activities in twelve human cancer cell lines. Of these, the extracts of C. lansium, L. indica, P. bleo, S. crispus, V. amygdalina and V. trifolia exhibited promising anti-proliferative activity against multiple cancer cell lines. Further investigation of selected promising leaf extracts indicated that maceration methanolic extract of L. indica was most effective overall against majority of the cancer cell lines, with best IC₅₀ values of 31.5 ± 11.4 µg/mL, 37.5 ± 0.7 µg/mL and 43.0 ± 6.2 µg/mL in cervical C33A, liver SNU-449, and ovarian PA-1 cancer cell lines, respectively.

CONCLUSION

The results of this study provide new scientific evidence for the traditional use of local medicinal plant species C. lansium, L . indica, P. bleo, S. crispus, V. amygdalina and V. trifolia in cancer treatment. These results highlight the importance of the upkeep of these indigenous plants in modern society and their relevance as resources for drug discovery.