Search company, investor...

Croton Media

croton.com.cn

About Croton Media

Croton Media is a media and film production company. It is based in Shanghai, China.

Headquarters Location

South HongKong Plaza 283 HuaiHai Zhong Road 38F

Shanghai, Shanghai,

China

Missing: Croton Media's Product Demo & Case Studies

Promote your product offering to tech buyers.

Reach 1000s of buyers who use CB Insights to identify vendors, demo products, and make purchasing decisions.

Missing: Croton Media's Product & Differentiators

Don’t let your products get skipped. Buyers use our vendor rankings to shortlist companies and drive requests for proposals (RFPs).

Latest Croton Media News

In Vitro Cytotoxicity and Anti-HIV Activity of Crude Extracts of Croton macrostachyus, Croton megalocarpus and Croton dichogamus

Dec 21, 2021

: is the optical density of the negative control-infected untreated HIV-infected cells. : is the optical density for the control-uninfected untreated (with no virus) cells. The effective inhibitory concentration at 50% (IC50) values were calculated from the percent cell protection results by non-linear regression analysis. The IC50 is defined as the concentration of the test compound that achieves 50% protection in infected cultures. The selectivity index (SI) of the test compounds were calculated as the ratio of 50% cytotoxic concentration (CC 50) to 50% effective concentration (IC50). Statistical Analysis The CC50 and IC50 values were calculated with GraphPad Prism v9, using the equation for sigmoidal dose-response (variable slope). Statistical significances in comparison between control drugs and extracts cytotoxicity and antiviral activity parameters (CC50, EmaxC, IC50 and EmaxAV) were determined by one-way ANOVA followed by Dunnett’s post-hoc tests, a difference was considered significant when p < 0.05. Results Yield of Plant Extraction Table 1 depicts the percentage yield obtained from the leaves and stem bark of Croton macrostachyus and Croton megalocarpus, and the aerial parts of Croton dichogamus. Table 1 Summary of Plants Collected and the Weight of Extracts Phytochemical Screening Phytochemical screening of the crude extracts of Croton macrostachyus, Croton megalocarpus, and Croton dichogamus had revealed the presence of different secondary metabolites ( Table 2 ). Table 2 Phytochemical Analysis for Crude Extracts of Croton macrostachyus and Croton megalocarpus, and Croton dichogamus Cytotoxicity Assay The cytotoxicity and anti-HIV-1 activity of the tested extracts and control using MT4 cell line are summarized in Table 3 . Among the tested extracts, the crude bark extract of Croton macrostachyus (AC) has the highest CC50 value of 45.9 ± 0.12 µg/mL followed by crude leaf extract of Croton megalocarpus (ELC) with a CC50 value of 27.7 ± 0.65 µg/mL. Among the tested extracts, highest value for maximum non-toxic concentration (MNTC) was achieved by the ELC extract at 20.56 ± 0.00 µg/mL indicating its relative safety on the cell lines. The efficacy (Emaxc) of the crude leaf extracts of Croton macrostachyus (ALC) and ELC on cell viability showed that they have less effect (Emaxc < 40%) in suppressing cell viability as compared to the other extracts. AC was found to have higher inhibition of cell growth (Emaxc = 49.96%) as compared to the other extracts. Table 3 Cytotoxicity and Anti-HIV-1 Activities of Control Drugs and Extracts Using MT4 Cell Line Among the FDA approved antiretreoviral drugs, zidovudine (AZT) and nevirapine (NVP) showed higher cytotoxicity (EmaxC > 35%) with CC50 value of 0.53 ± 0.29 and 0.82 ± 0.0 µg/mL respectively as compared with tenofovir (TDF) and abacavir (ABC). Based on our findings, all the tested extracts showed maximum cytotoxic effect (EmaxC) that is non-significantly higher than that of the control drugs; on the other hand, the CC50 was not significantly different between the extracts and control drugs, except for extract AC which showed significantly higher (P < 0.01) CC50 as compared with the four control drugs and ELC which showed significantly higher (P < 0.05) CC50 values as compared to AZT, ABC, and NVP ( Figure 1 ). From the results, the extracts with the closest cytotoxic effect to the control drugs were extracts ELC and ALC (Emaxc < 40%), the other three extracts EC, AC and CDC showed higher toxicity (Emaxc > 42%). Figure 1 CC50 and maximum cytotoxic effect in % (EmaxC) of extracts and controls (A–H). Results expressed are the mean of three independent experiments ± S.E.M. *Denotes p value < 0.05 and ** Denotes p value < 0.01. Abbreviations: C, control; AC, Croton macrostachyus bark extract; ALC, Croton macrostachyus leaf extract; EC, Croton megalocarpus bark extract; ELC, Croton megalocarpus leaf extract; CDC, Croton dichogamus aerial part extract; ns; not significant. Anti-HIV Assay Based on our antiviral assay results, higher anti-HIV activity was observed by crude leaf extracts of C. megalocarpus (ELC) and crude aerial part extracts of C. dichogamus (CDC) extracts. CDC displayed the highest anti-HIV activity by inhibiting 73.74% of viral induced cytopathic effect at an IC50 value of 0.001 + 0.00 μg/mL giving a selectivity index of 3116.0. Similarly, ELC displayed a higher anti-HIV activity by inhibiting 74.65% of CPE at IC50 value of 0.05 + 0.03 μg/mL giving a selectivity index (SI) of 571.3. The crude bark extract of Croton megalocarpus (EC) showed lower potency with IC50 value of 3.73 + 1.20 µg/mL, while the crude leaf extract of Croton macrostachyus (ALC) displayed very narrow selectivity index ( Table 3 ). As displayed in Figure 2 , the crude bark extract of C. megalocarpus (EC) has a significantly higher (P < 0.01) IC50 value as compared to the positive controls. However, comparing the antiviral efficacy (EmaxAV), all the tested extracts showed similar efficacy to the control drugs as they showed non-significantly different maximum inhibitions of viral induced CPE when compared to the control drugs. Figure 2 IC50 and maximum inhibition % (Emax) values of extracts and controls (A–H). Results expressed are mean of three independent experiments ± S.E.M. *Denotes p value < 0.05, **Denotes p value < 0.01. Abbreviations: C, control; AC, Croton macrostachyus bark extract; ALC, Croton macrostachyus leaf extract; EC, Croton megalocarpus bark extract; ELC, Croton megalocarpus leaf extract; CDC, Croton dichogamus aerial part extract; ns, not significant. It was found that the percentage of growth inhibition increased with increasing concentration of test compounds. Figure 3 depicts the concentration – response curve for the cell viability % and the inhibition % of the viral induced cytopathic effect associated with the tested substances. Despite its relatively higher cytotoxicity (42% inhibition of cell viability), the crude extract of Croton dichogamus has displayed strong activity with IC50 of 0.001 μg/mL giving an SI of 3115.97. Among the FDA approved standard drugs, zidovudine displayed the highest antiviral activity with 83% CPE inhibition at IC50 value of 0.001 µg/mL giving an SI of 279.4. Selectivity index reflects both antiviral activity and eventual toxicity of the test compounds. The high SI value indicates the low toxicity of the test compound and high activity against the virus. A dose-response curve was plotted to enable the calculation of the concentrations that reduced the viral replication by 50% (IC50). 15 , 16 , 27 Figure 3 Concentration–response curve analysis for the cell viability % (red line), and the inhibition % of the viral induced cytopathic effect (blue line) associated with extracts and controls. Results presented in the curves are means ± S.E.M. of three independent experiments. Abbreviations: AC, Croton macrostachyus bark extract; ALC, Croton macrostachyus leaf extract; EC, Croton megalocarpus bark extract; ELC, Croton megalocarpus leaf extract; CDC, Croton dichogamus aerial part extract. Discussion Currently available anti-HIV drugs are chemically synthesized and are often limited by side effects and emergence of drug resistance. 28 On top of this, still over 5 million people do not have access to the treatments. 1 Therefore, all possible approaches towards the development of new anti-HIV drugs should be pursued. This calls for a need to identify local, alternative, less expensive and less toxic drugs for treatment of HIV. A potential source of thiese demands is of natural products. 29 Natural products are the major source of new active pharmaceutical ingredients for treatment of infectious diseases including HIV/AIDs. 30–32 In order to find potential anti-HIV agents from natural sources, we evaluated the cytotoxicity and anti-HIV activities of three Croton species including Croton macrostachyus, Croton megalocarpus and Croton dichogamus against laboratory adapted strains of HIV (HIV-1IIIB) in Human T-lymphocytic MT-4 cells. In this study, human T-lymphocytic MT-4 cells were used. Lymphocyte cell line, MT-4, which carries the HTLV-I genome is highly susceptible to HIV infection. 33 The MT-4 cells were inoculated with HIV showed a markedly different cell growth and viability pattern when compared with mock infected cells. The number of viable cells rapidly decreased at 24 hours post infection, and by day 4 only 2–4% of the infected MT-4 cells were viable. In contrast, the mock-infected cells grew well, reaching a plateau between days 2 and 4. After 4 days, the viability of these cells began to decline appreciably. The infected cells became round, lost their surface characteristics, became refractile and diminished in size. By day 3, many infected cells developed a balloon-like, cytoplasmic swelling, a morphological observation which later disappeared. The dose of virus influenced the number of viable cells and the time course of appearance of these cytopathic effects. These observations were in agreement with previous reports of many scholars who used the MT-4 cell line to evaluate anti-HIV activity of various compounds. 16 , 18 , 34 , 35 The effects of the test compounds in preventing cytopathic effect which occurs as a result of HIV-1 replication was evaluated by MTT colorimetric assay. Human immunodeficiency virus type 1 (HIV-1IIIB) laboratory adapted strain, was obtained from the NIH HIV Reagent Program. HIV-infected MT-4 cells were seeded in 96-well flat-bottomed microtitre culture plates with 50 µL of different concentrations (800–8.192×105 μg/mL) of the test compounds. To ensure the safety of the extracts on human T-Lymphocytes, a cytotoxicity test was conducted using MT-4 cell lines. Based on our results, Croton megalocarpus leaf extracts (ELC) and Croton macrostachyus leaf extracts (ALC) were relatively less toxic as compared to the other extracts and are with the closest cytotoxic effect to the control drugs, while the other three extracts EC, AC and CDC showed higher toxicity. The phytochemical analysis in the current study confirmed the presence of flavonoids, saponins, phenolic compounds and terpenes in these crude extracts ( Table 2 ). Previous phytochemical analysis studies from these plants revealed the presence of phytosterols, 36 terpenes, 37 triterpenoids, 37–40 diterpenoids 41–43 and phenolic compounds 36 , 38 and fatty acids. 44 The difference in the cytotoxicity in these extracts could be attributed to the phytochemical ratios of tannins, alkaloids, flavonoids, phenols, and terpenoids in them. 45 The higher potency of Croton megalocarpus (ELC) extract (CC50= 27.73 µg/mL, IC50= 0.05 µg/mL and SI = 571.3) to inhibit the cytopathic effect by the virus could be due to the saponins in the leaf of the plant. Previous studies have shown the efficacy of saponins isolated from soybean seeds in inhibiting HIV-1 replication in MT-4 cells. 46 In another study acetin, a tetracyclic saponin isolated from the rhizome of Cimicifuga racemosa (black cohosh), showed potent anti-HIV activity. 47 The observed efficacy could also be attributed to the diterpenes in the plant. Previous studies have shown the presence of terpenes, diterpenoids and triterpenoids in the stem bark and roots of Croton megalocarpus and Croton macrostachyus. 41 , 42 , 48 Moderate anti-HIV activity was reported from cyanthiwigin B, a diterpene isolated from the Jamaican sponge Myrmekioderma styx in cell based in vitro assay. Similarly other diterpenes like betulinic acid, platanic acid and oleanolic acid isolated from the leaves of Syzygium claviflorum have exhibited anti-HIV activity. 49 Furthermore, the efficacy of the plants in this study could also be due to the flavonoids, as some flavonoids have been shown to have HIV inhibitory potential and also in reducing oxidative stress. 50 Polyphenols and flavonoids are known to stabilize membranes and to prevent lipid peroxidation, a key process in the onset, progression and complication of many pathologies. This study is important because it served as a starting point in the discovery of new cytotoxic agents and the unveiling of the potent extracts from three Croton species with tremendous traditional use in Africa. Conclusion To conclude, out of five extracts from three Croton species screened for anti-HIV activity using Human T-lymphocytic MT-4 cells, the leaf extract of Croton megalocarpus and aerial part extract of Croton dichogamus could be considered as promising extracts as they display high antiviral activity with low toxicity and high SI values. Further studies to determine the mechanism of action of these plants as anti-HIV agents are needed. Moreover, research is needed to isolate and identify the active phytoconstituents responsible for the cytotoxic and anti-HIV efficacy in these plants. Therefore, currently we are working on isolating pure compounds from the different solvent fractions so as to determine the mechanism of action of isolated compounds on different viral protein. Ethical Approval The research was approved by Kenyatta National Hospital-University of Nairobi Ethics and Research Committee (KNH-UON ERC), approval number P992/12/2019. Acknowledgments The authors would like to extend their gratitude to the United States International University - Africa Internal grant no. 10-2854, and University of Nairobi, Kenya Medical Research institute and the Institute of Primate Research for their support toward the successful completion of the research work. Disclosure References

Croton Media Web Traffic

Rank
Page Views per User (PVPU)
Page Views per Million (PVPM)
Reach per Million (RPM)
CBI Logo

Croton Media Rank

Croton Media Frequently Asked Questions (FAQ)

  • Where is Croton Media's headquarters?

    Croton Media's headquarters is located at South HongKong Plaza 283 HuaiHai Zhong Road, Shanghai.

Discover the right solution for your team

The CB Insights tech market intelligence platform analyzes millions of data points on vendors, products, partnerships, and patents to help your team find their next technology solution.

Request a demo

CBI websites generally use certain cookies to enable better interactions with our sites and services. Use of these cookies, which may be stored on your device, permits us to improve and customize your experience. You can read more about your cookie choices at our privacy policy here. By continuing to use this site you are consenting to these choices.