Sulfonamide chalcones: Synthesis and in vitro exploration for therapeutic potential against Brugia malayi.

Keeping in mind the immense biological potential of chalcones and sulfonamide scaffolds, a library of sulfonamide chalcones has been synthesized and evaluated for in vitro antifilarial assay against human lymphatic filarial parasite Brugia malayi. Experimental evidence showcased for the first time the potential of some sulfonamide chalcones as effective and safe antifilarial lead molecules against human lymphatic filarial parasite B. malayi. Sulfonamide chalcones 4d, 4p, 4q, 4t and 4aa displayed the significantly wide therapeutic window. Particularly chalcones with halogen substitution in aromatic ring proved to be potent antifilarial agents against Brugia malayi. Sulphonamide chalcones with lipophilic methyl moiety (4q and 4aa) at para position of terminal phenyl rings of compounds were found to have remarkable antifilarial activities with therapeutic efficacy. Observed preliminary evidence of apoptosis by effective chalcone derivatives envisaged its fair possibility to inhibit folate pathway with consequent defect in DNA synthesis.

Filaricidal activities on Onchocerca ochengi and Loa loa, toxicity and phytochemical screening of extracts of Tragia benthami and Piper umbellatum.

BACKGROUND: Onchocerciasis is the world's second leading infectious cause of blindness. Its control is currently hampered by the lack of a macrofilaricidal drug and by severe adverse events observed when the lone recommended microfilaricide, ivermectin is administered to individuals co-infected with Loa loa. Therefore, there is the need for a safe and effective macrofilaricidal drug that will be able to cure the infection and break transmission cycles, or at least, an alternative microfilaricide that does not kill L. loa microfilariae (mf). METHODS: Fourteen extracts from two medicinal plants, Tragia benthami and Piper umbellatum were screened in vitro against Onchocerca ochengi parasite and L. loa mf. Activities of extracts on male worms and microfilariae were assessed by motility reduction, while MTT/Formazan assay was used to assess biochemically the death of female worms. Cytotoxicity and acute toxicity of active extracts were tested on monkey kidney cells and Balb/c mice, respectively. RESULTS: At 500 µg/mL, all extracts showed 100 % activity on Onchocerca ochengi males and microfilariae, while 9 showed 100 % activity on female worms. The methylene chloride extract of Piper umbellatum leaves was the most active on adult male and female worms (IC50s: 16.63 µg/mL and 35.65 µg/mL, respectively). The three most active extracts on Onchocerca ochengi females were also highly active on Loa loa microfilariae, with IC50s of 35.12 - 13.9 µg/mL. Active extracts were generally more toxic to the worms than to cells and showed no acute toxicity to Balb/c mice. Phytochemical screening revealed the presence of saponins, steroids, tannins and flavanoids in the promising extracts. CONCLUSIONS: These results unfold potential sources of novel anti-Onchocerca lead compounds and validate the traditional use of the plants in onchocerciasis treatment.

Anti-Onchocerca activity and phytochemical analysis of an essential oil from Cyperus articulatus L.

BACKGROUND: The lack of a safe and effective adult worm drug and the emergence of resistant animal parasite strains to the only recommended drug, the microfilaricide, ivermectin put many at risk of the devastating effects of the onchocerciasis. The present study was undertaken to investigate the acclaimed anti-Onchocerca activity of the roots/rhizomes of Cyperus articulatus in the traditional treatment of onchocerciasis in North Western Cameroon and to assess the plant as a new source of potential filaricidal lead compounds. METHODS: Crude extracts were prepared from the dried plant parts using hexane, methylene chloride and methanol. The antifilarial activity was evaluated in vitro on microfilariae (Mfs) and adult worms of the bovine derived Onchocerca ochengi, a close relative of Onchocerca volvulus. The viabilities of microfilariae and adult male worms were determined based on motility reduction, while for the adult female worms the viability was based on the standard MTT/formazan assay. Cytotoxicity of the active extract was assessed on monkey kidney epithelial cells in vitro and the selectivity indices (SI) were determined. Acute toxicity of the promising extract was investigated in mice. Chemical composition of the active extract was unraveled by GC/MS analysis. RESULTS: Only the hexane extract, an essential oil exhibited anti-Onchocerca activity. The oil killed both the microfilariae and adult worms of O. ochengi in a dose manner dependently, with IC50s of 23.4 µg/ml on the Mfs, 23.4 µg/ml on adult male worms and 31.25 µg/ml on the adult female worms. Selectivity indices were 4, 4, and 2.99 for Mfs, adult males and adult females, respectively. At a single limit dose of 2000 mg/kg body weight, none of 6 mice that received the essential oil by gavage died. GC/MS analysis revealed the presence of terpenoids, hydrocarbons and fatty acids or fatty acid derivatives as components of the oil. CONCLUSIONS: The essential oil from the roots/rhizomes of Cyperus articulatus is active against O. ochengi microfilariae and adult worms in vitro in a dose dependent manner, hence may provide a source of new anti-filarial compounds. The results also support the traditional use of C. articulatus in the treatment of human onchocerciasis.

Morphological changes in the testis induced by diethylcarbamazine.

Diethylcarbamazine (DEC) had been proved to be highly effective against lymphatic filariasis, however its effect on vertebrate cells remains uncertain. After 12 days treatment with DEC, most of the Leydig cells were hypertrophied with several lipid droplets, and others had no nucleus and presented characteristic steatosis features. Vacuolization of Sertoli cells was also noted. Ultrastructural analyses of DEC-treated testes revealed spermatogonies with morphological characteristics of apoptosis, as shrinkage of cytoplasm and increased chromosomal density. In addition, Leydig cells showed numerous lipid droplets scattered throughout the cytoplasm, multivesicular bodies and giant whorl-like smooth endoplasmic reticulum. Several spermatids presented vacuolated mitochondriae, which were disorganized in relation to the microtubular axis of the flagellae. These results indicate that DEC probably affects the microtubular function, however the present data does not exclude the possibility that DEC also can act directly on enzymatic hormonal pathways.

Macrofilaricidal and microfilaricidal effects of Neurolaena lobata, a Guatemalan medicinal plant, on Brugia pahangi.

Twelve extracts of 11 Guatemalan medicinal plants were initially screened in vitro for potential macrofilaricidal activity against Brugia pahangi, a lymphatic dwelling filarial worm, using concentrations from 125 to 1000 microg ml(-1) of each extract that could be dissolved in the culture medium. Of 12 extracts used, the ethanol extract of leaves of Neurolaena lobata showed the strongest activity against the motility of adult worms. Subsequently, the extract of N. lobata was extensively examined in vitro for macro- and micro-filaricidal effects using a series of concentrations of 500, 250, 100, 50 and 10 microg ml(-1). The effects were assessed by worm motility, microfilarial release by female worms and a MTT assay. The effect on the motility of adult worms was observed in a concentration- and time-dependent manner. The time required to stop motility of both sexes of adult worms was 6 h at 500 microg ml(-1), 24 h at 250 microg ml(-1), and 3 days for females and 4 days for males at 100 microg ml(-1). The movement of females ceased at 4 days at a concentration of 50 microg ml(-1) whereas the motility of males was only reduced. The loss of worm's viability was confirmed by the MTT assay and was similar to the motility results. These concentrations, including 10 microg ml(-1), prevented microfilarial release by females in a concentration- and time-dependent manner. Concentrations higher than 100 microg ml(-1) even induced mortality of the microfilariae. The present study suggested that the ethanol extract of Neurolaena lobata has potential macro- and micro-filaricidal activities.

The in vitro effect of albendazole, ivermectin, diethylcarbamazine, and their combinations against infective third-stage larvae of nocturnally subperiodic Brugia malayi (Narathiwat strain): scanning electron microscopy.

Scanning electron microscopy (SEM) was employed to observe the effects of ivermectin (IVM), diethylcarbamazine (DEC), and albendazole (ALB) alone, and the drugs in combination (ALB+IVM and ALB+DEC) against infective third stage larvae (L3) of nocturnally subperiodic (NSP) Brugia malayi (Narathiwat strain) in vitro. IVM, at a concentration of 10(-4) M, killed L3 within 1-2 h. The SEM data showed damage to the L3 surface and loss of regular cuticular annulations. The cuticles were grooved in the middle region of the body. In comparison with normal L3 before treatment with IVM, the cuticular surface showed transversed striations with periodic annulations. The result demonstrated that IVM showed a larvicidal activity against L3 of NSP B. malayi cultivated in vitro. Compared with those larvae in the control group, the treated larvae had no morphological changes in the cuticular surface at the head, body, and tail regions after cultivation with all drugs alone, and in their combinations at a concentration of 10(-5) M for 7 d. In this system, and at that concentration, only the larvae cultured with ALB alone remained highly motile. Although no morphological changes had been observed by SEM, those drugs used alone (IVM and DEC) and in combinations (ALB+IVM and ALB+DEC), reduced larval motility throughout the experiments at a concentration of 10(-5) M. The minimum lethal concentration (MIC) of IVM against NSP B. malayi was 10(-4) M.

Comparative assessment of the in vitro sensitivity of Brugia malayi infective larvae to albendazole, diethylcarbamazine and ivermectin alone and in combination.

The antifilaricidal drugs ivermectin (IVM), diethylcarbamazine (DEC), and albendazole (ALB), used alone or in combinations against infective third-stage larvae (L3) of nocturnally subperiodic (NSP) Brugia malayi (Narathiwat strain), were tested in vitro for sensitivity, for 7 days. IVM alone reduced larval motility at concentrations of 10(-7), 10(-6), and 10(-5) M on day 3. DEC alone also had this effect at concentrations of 10(-6). 10(-5), and 10(-4) M on day 2. ALB alone did not have this effect throughout the experiment, at various concentrations. However, it had greater effect when used in combination with either DEC or IVM. The result also indicated that DEC or IVM, when used in combination with ALB at concentrations of 10(-6) M/10(-6) M, and 10(-5) M/10(-5) M was effectively better than each drug used alone at those concentrations. When both drug combinations were compared, ALB/DEC seemed to be more effective than ALB/IVM at a concentration of 10(-6) M/10(-6) M on day 3. Although IVM and DEC can reduce larval motility when used alone or in combination with ALB, they cannot kill these larvae in an in vitro cultivation, even at a high concentration (10(-5) M).

In vitro antifilarial effects of three plant species against adult worms of subperiodic Brugia malayi.

Five aqueous extracts from three plant species, i.e., dried husks (HX), dried seeds (SX) and dried leaves (LX) of Xylocarpus granatum (Meliaceae), dried stems (ST) of Tinospora crispa (Menispermaceae) and dried leaves (LA) of Andrographis paniculata (Acanthaceae) were tested in vitro against adult worms of subperiodic Brugia malayi. The relative movability (RM) value of the adult worms over the 24-h observation period was used as a measure of the antifilarial activity of the aqueous extracts. SX extract of X. granatum demonstrated the strongest activity, followed by the LA extract of A. paniculata, ST extract of T. crispa, HX extract and LX extract of X. granatum.

2,2'-Dicarbomethoxyamino-5,5'-dibenzimidazolyl ketone--a new antifilarial agent.

The activity of 2,2'-dicarbomethoxyamino-5,5'-dibenzimidazolyl ketone (II, C.D.R.I. Comp. 82/437) has been evaluated for its micro- and macro-filaricidal efficacy against Litomosoides carinii in rodents. A dose of 3 mg/kg (i.p.) and 50 mg/kg (oral) x 5 days of Comp. 82/437 was found to eliminate almost 100% of adult worms and microfilariae of L. carinii in cotton rat. It also killed 100% and 97% of adult worms and microfilariae of Dipetalonema viteae and Brugia malayi in Mastomys natalensis respectively, at 150 and 200 mg/kg x 5 days orally. The compound also exhibited marked chemoprophylactic and in vitro activity against L. carinii.

Filaricidal properties of a wild herb, Andrographis paniculata.

Water decoction of the leaves of Andrographis paniculata killed in vitro the microfilaria of Dipetalonema reconditum in 40 min. Three subcutaneous injections of the extract into infected dogs at 0.06 ml per kg body-weight reduced the number of microfilariae in blood by more than 85%. The larvae were not totally eliminated with more infections but the reduced microfilarial level persisted. No toxic effect of the extract was observed in rabbits. The treated dogs became lethargic initially for a week, probably due to the mass killing of microfilariae.