The previous study showed that xanthone had antiplasmodial activity. Xanthone, with additional hydroxyl groups, was synthesized to increase its antiplasmodial activity. One of the strategies to evaluate a compound that can be developed into an antimalarial drug is by testing its mechanism in inhibiting heme polymerization. In acidic condition, hematin can be polymerized to β-hematin in vitro, which is analog with hemozoin in Plasmodium. This study was conducted to evaluate the antiplasmodial activity of hydroxyxanthone derivative compounds on two strains of Plasmodium falciparum 3D-7 and FCR-3, to assess inhibition of heme polymerization activity and determine the selectivity of hydroxyxanthone derivative compounds. The antiplasmodial activity of each compound was tested on Plasmodium falciparum 3D-7 and FCR-3 with 72 hours incubation period, triplicated in three replications with the microscopic method. The compound that showed the best antiplasmodial activity underwent flow cytometry assay. Heme polymerization inhibition test was performed using the in vitro heme polymerization inhibition activity (HPIA) assay. The antiplasmodial activity and heme polymerization inhibition activity were expressed as the 50% inhibitory concentration (IC50). In vitro cytotoxicity was tested using the MTT assay method on Vero cell lines to determine its selectivity index. The results showed that among 5-hydroxyxanthone derivative compounds, the 1,6,8-trihydroxyxanthone had the best in vitro antiplasmodial activity on both 3D-7 and FCR-3 Plasmodium falciparum strains with IC50 values of 6.10 ± 2.01 and 6.76 ± 2.38 μM, respectively. The 1,6,8-trihydroxyxanthone showed inhibition activity of heme polymerization with IC50 value of 2.854 mM and showed the high selectivity with selectivity index of 502.2–556.54. In conclusion, among 5-hydroxyxanthone derivatives tested, the 1,6,8-trihydroxyxantone showed the best antiplasmodial activity and has heme polymerization inhibition activity and high selectivity.

Purpose: To investigate the antiplasmodial and onset of growth inhibitory activities of T. diversifolia fractions against Plasmodium falciparum FCR3 strain. Methods: Seven fractions of T. diversifolia (F1-F7) were used in this study. Phytochemical analysis was conducted to identify the major compounds in the fractions. Various concentrations of fractions ranging from 2.5-100.0 µg/mL were exposed to P. falciparum FCR3 strain for 60 h and the growth inhibition was then calculated. The fraction which exhibited the best antiplasmodial activity was tested further to determine the growth inhibition onset against P. falciparum FCR3 strain. This was achieved by examining the inhibitory activity of the fraction when it was added at the beginning of the experiment and assessing subsequent parasite growth after 8, 16, 24, 32, and 40 h incubation. Results: The major compounds found in the fractions were terpenes. Fraction six (F6) had the best antiplasmodial activity (IC50 13.63 ± 1.43 µg/mL). During the first 32 h of incubation, F6 inhibited the growth of parasites and this increased with longer incubation time; 32 h incubation provided the highest growth inhibition (99.23 ± 0.05 %). After 32 h the inhibition activity began to decrease, and resulted in < 50 % inhibition at 48 h incubation. This result suggested that F6 is a rapid-onset antiplasmodial agent. Conclusion: Fractions of T. diversifolia, especially F6, are promising antimalarial agents and require further development for clinical application.

Previous research revealed that the extracts and fractions of Tithonia diversifolia (Hemsley) A.Gray leaves had antiplasmodial activity in vitro. For further development as an antiplasmodial agent, the mechanisms of action and safety of compounds are important to disclose. Heme polymerization inhibition is one of the main targets of antiplasmodial action. The aim of the study was to investigate the activity of T. diversifolia fractions in inhibiting heme polymerization and its cytotoxic effect on Vero cells. Heme polymerization inhibition assay from Bassilico and cytotoxic test on Vero cell using MTT method were conducted for three fractions (F5, F6, and F7) of T. diversifolia leaves. The inhibitory activity of heme polymerization expressed as IC50 and cytotoxicity effect expressed as CC50 were determined by probit analysis. The best heme polymerization inhibition activity was F5 with IC50 = 162.20 ± 57.81 μg/mL followed by F6 and F7 with IC50 216.30 ± 26.56 and 231.54 ± 44.26 μg/mL respectively. All the fractions had a low cytotoxic effect with CC50 for F5, F6, and F7 were over than 100, 34.81 ± 9.94 and 56.26 ± 6.73 μg/mL, respectively and the toxicity index fraction is below 10 or categorized as low selectivity. Conclusion: The fraction of T. diversifolia inhibited heme polymerization in vitro and had low cytotoxic effect on Vero cells but no selective toxicity. Further research using pure compounds may improve its selectivity.

The objectives of the study were to evaluate the effect of ethanolic extract of P. indica Less leaf (EPI) on serum growth hormone (GH), milk yield, body weight gain of dams, and dam’s organ weight in lactating rats. A total of 25 lactating rats with six pups were randomized and distributed to one of five treatments (control (RO water), standard (domperidone 2,5 mg/kg BW/day), EPI 250 (250 mg/kg BW of EPI), EPI 500 (500 mg/kg BW of EPI), and EPI 750 (750 mg/kg BW of EPI)). The treatment was administered daily starting from the 2nd until the 15th day of lactation. On the 16th day serum growth hormone level, body and organ weight of rats were measured. Serum GH levels in the EPI 750 group (1963.25 ± 360.91 pg/µL) increased significantly compared to the domperidone (409.46 ± 28.80 pg/µL) and the control group (723.40 ± 95.78 pg/µL, p0.05). There was significant body weight gain in the EPI 750 group compared with the domperidone group. There was no significant difference in organ weight gain in each group. The study revealed that ethanolic extract of P. indica Less leaf can increase serum growth hormone in lactating rats.

Penelitian terdahulu menunjukkan bahwa fraksi ke-6 (F6) merupakan fraksi aktif (F-akt) daun Tithonia diversifolia (Hemsley) A.Gray yang menghambat pertumbuhan Plasmodium. Pertumbuhan parasit ini memerlukan energi yang diperoleh dari aktivitas laktat dehidrogenase (LDH). Penelitian ini bertujuan mengkaji aktivitas antiplasmodium fraksi aktif T. diversifolia terhadap kadar LDH kultur P. falciparum. Kultur Plasmodium falciparum strain D10 stadium cincin dibagi menjadi kelompok eritrosit tidak terinfeksi (KTI), eritrosit terinfeksi (KI), dan eritrosit terinfeksi Plasmodium yang diberi F6 (F-akt) T. diversifolia (KI+F-akt) konsentrasi 9,38-150 µg/mL. Kultur diinkubasi 48 jam. Media kultur diukur kadar LDH-nya secara enzimatik. Adanya perbedaan LDH antar kelompok dianalisa dengan Anova. Penghambatan aktivitas LDH (IC50) ditetapkan dengan analisa probit. Kadar LDH kelompok KI (362,33 ± 133,18 U/L) lebih tinggi daripada KTI (270,33 ± 65,85 U/L) (p>0,05). Pemberian F-akt pada KI menyebabkan kadar LDH parasit lebih rendah daripada KI. Kadar LDH parasit yang diberi F-akt konsentrasi 9,38; 18,75; 37,50; dan 150 µg/mL secara berturut-turut adalah 365,5 ± 129,5; 210,5 ± 1,5; 195,5 ± 81,5; dan 111,5 ± 53,5 U/L. Tidak ada perbedaan kadar LDH antar kelompok penelitian (p>0,05). F-akt  T. diversifolia mampu menghambat LDH P. falciparum strain D10 dengan nilai IC50 = 39,22 µg/mL.Kata kunci: Tithonia diversifolia, laktat dehidrogenase, Plasmodium falciparum