Further Studies on the Antinociceptive Action of the Hydroalcoholic Extracts from Plants of the Genus, Phyllanthus

Abstract

The analgesic effects of the hydroalcoholic extracts (HEs) of Phyllanthus urinaria, P. tenellus, P. niruri and P. sellowianus have been investigated in several models of nociception in mice.The HE of four species of Phyllanthus (1-90mg kg-l, i.p.) caused a dose-related inhibition of acetic acid-induced abdominal constriction in mice with ID50 values of 5.4, 8.5, 18.2 and 53.0mgkg-I and maximal inhibition (%) of 80 f 2, 67 f 8, 63 f 8 and 50 f 4 for P. urinaria, P. niruri, P. tenellus and P. sellowianus, respectively. In the formalin test, the HE of all Phyllanthus species (0.3-60mg kg-I, i.p.) caused graded inhibition of both phases of formalin-induced pain, but they were, however, more potent in relation to the second phase of the pain. The ID50 values (mg kg-I) for the first phase were 20.0,23.0, > 60, and > 60 for the P. urinaria, P. tenellus, P. niruri and P. sellowianus, respectively, and percentages of maximal inhibition were 63 f 2,70 f 2,41 f 3 and 46 f 4, respectively. The ID50 values (mg kg-I) for the second phase were 0.71,4.87, 7.7, 33.0, with maximal inhibition (%) of 91 f 6, 97 * 3, 97 f 3 and 92 * 6, respectively. Given orally, the HEs of species of Phyllanthus caused a significant antinociceptive profile, but they were about one-tenth to one-twentieth as potent when given intraperitoneally. However, the HEs of Phyllanthus failed to affect formalin-induced paw oedema and did not interfere with the performance of animals in the rota-rod test. Naloxone (5 mg kg-') completely reversed the analgesic effect caused by morphine (5 mg kg-I), but had no effect against the analgesic effect of the HE of Phyllanthus. Furthermore, the HEs of Phyllanthus in contrast to morphine had no analgesic effect in either tail-fick or hot-plate tests.Taken together, these findings confirm and extend our previous results and indicate that all studied HE of species of plant belonging to the genus Phyllanthus exhibit potent and long-lasting antinociceptive activity in several models of pain, including the neurogenic algesic component of the formalin test. The mechanism underlying their analgesic profile is presently unknown.

Identification of biologically active triterpenes and sterols present in hexane extracts fromMiconia species using high-resolution gas chromatography

“…These results clearly demonstrate that the chemical profile of the six Miconia species concerning triterpenes and sterols are very similar. It has been reported that a mixture of these compounds is responsible for the biological activities of the extracts they are isolated from (Santos et al, 1995;Gaertner et al, 1999;Otuki et al, 2005). In this context, our data might indicate that the previously reported analgesic effect of the hexane extracts of M. rubiginosa and M. ligustroides in mice could be due to the presence of these compounds.…”

The mechanisms underlying the relaxant effect of methyl and ethyl gallates in the guinea pig trachea in vitro: contribution of potassium channels

“…In earlier studies, we have reported that the hydroalcoholic extract obtained from the leaves, stems and roots of Phyllanthus urinaria (Euphorbiaceae), and some related species belonging to this genus, cause dose-related and significant antinociception, mainly when assessed in neurogenic models of nociception (Gorski et al 1993;Santos et al 1994Santos et al , 1995; see for review Calixto et al 1998).…”

Effects of the hydroalcoholic extract of Phyllanthus niruri and its isolated compounds on cyclophosphamide-induced hemorrhagic cystitis in mouse

“…Of high interest, pain-like crises induced by CYP were consistently prevented by oral treatment with the hydroalcoholic extract from P. niruri. In fact, previous studies revealed marked analgesic effects for this plant extract in several models of nociception in mice (Santos et al 1994;Santos et al 1995;Martini et al 2000). We might suggest that antinociceptive actions of P. niruri extract are mainly related to the presence of compounds quercetin and gallic acid.…”