Plant gums are the salts of acidic polysaccharides and they arise when plants are injured, either mechanically or by the invasion of fungi or bacteria. In order to throw light on the mode of formation of these gums, several workers have investigated the chemical constitution and molecular structure of the materials. The work described in this thesis is concerned with the chemical constitution of the gums from the white cholla cactus, Opuntia fulgida, and the almond tree. The mode of linkage of the sugar residues present in cholla gum and egg-plum has also been investigated by the usual method of methylation, hydrolysis, and identification of the methylated sugar derivatives produced. The results obtained during the investigations do not allow unique molecular formulae to be proposed for the polysaccharides but certain structural similarities with other plant gums have been observed.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Using the osteoarthritis (OA) model induced by anterior cruciate ligament transection (ACLT) in rats, we have demonstred that guar gum (GG), a galactomannan extracted from Cyamopsis tetragonolobus seeds, displays analgesic activity similar to Hylan G-F 20, a hyaluronate derivate used as local therapy in human OA. In the same model, we objective to develop a parametric biochemical method for joint lesion evaluation, and to investigate the mechanism for analgesia and the chondroprotective effect of GG. Wistar rats subjected to ACLT (OA group) were sacrificed at different endpoints. Joint pain was daily measured using the test for articular incapacitation in rats, until 70 days. Joint lavage was used for NO determination. Articular cartilage was evaluated by the chondroitin-sulfate (CS) content and determination of its molar weight. Histophatologic analysis using the OARSI score system was also performed. Sham-operated groups were used for comparison. In the studies of joint pain, OA groups received indomethacin (2mg/kg/d s.c.), meloxicam (6mg/kg/d i.p.), tadalafil (0.5mg/kg/d p.o.) between days 4 and 7.Morphine (200Âg i.art.) was given at day 4 only, 30 min before the pain evaluation. Naloxone (500Âg i. art.) was given 15 min prior morphine. Sodium alendronate (30 or 240Âg i. art.) was given prophilactically, starting 3 days prior ACLT, and repeated at each 3 days, until day 6. Original or chemically modified GG (100&#956;g/50&#956;l i. art.) was given as a single dose at day 4. Galactose or mannose was co-administred (500&#956;g/50&#956;l i. art.) with original GG. In the study of chondroprotection, GG (100&#956;g/50&#956;l i. art.) was given once weekly, starting at day 14, during 8 weeks. Non-treated animals (NT) received vehicle (saline). OA animals presented maximal joint pain and NO release in the first week. Both CS content and molar weight were higher at day 70 (p<0.05). At this endpoint, important histopathologic changes were found in the OA group. Indomethacin, meloxican, tadalafil and morphine significantly reduced joint pain (p<0.05). Naloxone reverted the effect of morphine. Alendronate prevented the joint pain development. Modified GG structures were unable to promote analgesia. The analgesic effect of unmodified GG could be reverted by galactose (p<0.01), but not by mannose. GG treatment prevented the CS changes, and it reduced the histopatologic lesion (p<0.05). CS changes seem to reflect the tecidual damage, and may be used as an index for the joint lesion. The analgesic efficacy of GG is due to galactose residues. In addition, the chondroprotective effect by GG was demonstrated. This is an important contribution to propose GG as an antiarthrosic drug / No modelo de osteoartrite (OA) induzida por transecÃÃo do ligamento cruzado anterior em ratos (TLCA), havÃamos demonstrado que a goma guar (GG), uma galactomanana extraÃda das sementes de Cyamopsis tetragonolobus goma guar, apresenta atividade analgÃsica em magnitude semelhante à exibida pelo Hilano G-F 20, um derivado do Ãcido hialurÃnico utilizado em terapia intra-articular da OA humana. Utilizando o referido modelo, objetivamos desenvolver um mÃtido bioquÃmico paramÃtrico para avaliaÃÃo da lesÃo articular no referido modelo, e investigar o mecanismo para a analgesia e a eficÃcia condroprotetora da GG. Ratos Wistar submetidos à TLCA (grupo OA) foram sacrificados em diferentes perÃodos. A dor articular foi avaliada diariamente pelo teste de incapacitaÃÃo para ratos, por atà 70 dias. O lavado articular foi usado para determinaÃÃo da liberaÃÃo de NO. A cartilagem foi avaliada pela determinaÃÃo do teor de condrotin-sulfato (CS) na matriz, alÃm da avaliaÃÃo da massa molar do mesmo. A lesÃo articular foi avaliada tambÃm por anÃlise histopatolÃgica, segundo os escores OARSI. Grupos falso-operados (sham) foram utilizados para comparaÃÃo. Para estudos sobre a dor articular, animais do grupo OA receberam terapeuticamente indometacina (2mg/kg/d s.c.), meloxicam (6mg/kg/d i.p.), ou tadalafila (0,5mg/kg/d p.o.), do quarto ao sÃtimo dias. Morfina (200Âg i. art.) foi administrada apenas no quarto dia, 30 min antes da avaliaÃÃo da dor. Naloxona (500Âg i. art.) foi administrada 15 min antes de morfina. Alendronato sÃdico (30 ou 240Âg/kg s.c.) foi administrado profilaticamente trÃs dias antes da induÃÃo, e repetido a cada trÃs dias, atà o sexto dia. GG original ou quimicamente modificada foi administrada em dose Ãnica no quarto dia (100&#956;g/50&#956;l i. art.). Galactose ou manose (500&#956;g/50&#956;l i. art.) foram co-administrados à GG original. Para avaliaÃÃo sobre a lesÃo da cartilagem, GG (100&#956;g/50&#956;l i. art) foi administrada como dose Ãnica semanal, do 14 ao 63 dias. Animais nÃo tratados (NT) receberam veÃculo (salina) nas respectivas vias. O grupo OA apresentou dor articular mÃxima durante a primeira semana, perÃodo no qual houve a maior liberaÃÃo de NO. 70 dias apÃs TLCA, o teor e a massa molar do CS da matriz da cartilagem mostraram-se ambos aumentados (p<0,05). Importantes alteraÃÃes histopatolÃgicas foram encontradas no grupo OA nesse perÃodo. Indometacina, meloxicam, tadalafila e morfina reduziram significantemente a dor (p<0,05), sendo o efeito desta Ãltima revertido por naloxona. Alendronato sÃdico preveniu a ocorrÃncia da dor. As estruturas modificadas de GG nÃo exibiram eficÃcia analgÃsica. Galactose, mas nÃo manose, reverteu significativamente o efeito analgÃsico da GG nÃo-modificada (p<0,01). GG preveniu as alteraÃÃes do CS da cartilagem, e reduziu significativamente a lesÃo histopatolÃgica (p<0,05). As alteraÃÃes sofridas pelo CS parecem refletir o dano tecidual, validando tal metodologia para avaliaÃÃo da lesÃo estrutural. A eficÃcia analgÃsica da GG decorre de um efeito farmacolÃgico dependente de galactose. Mais ainda, demonstramos a eficÃcia condroprotetora in vivo para a GG, indispendÃvel para sua validaÃÃo como droga anti-artrÃsica.