Bioassay guided purification of cytotoxic natural products from a red alga Dichotomaria obtusata

ABSTRACT Different solvent extracts of Dichotomaria obtusata (J. Ellis & Solander) Lamark, Galaxauraceae, a red algae collected from the coast of Bushehr in the Persain Gulf, was investigated for its cytotoxic properties and chemical constituents. The fresh alga, after extraction with methanol and dichloromethane were combined and partitioned between water, dichloromethane and ethyl acetate. The above fractions were then tested against MOLT-4 (human lymphoblastic leukemia) cancer cell line. The IC50 values of the dichloromethane and ethyl acetate layers of the crude extract were 29.8 ± 3.1 and 30.6 ± 7.9 µg/ml against MOLT-4 cells, respectively, while the water layer showed a week activity with IC50 > 50 µg/ml. After fractionation of the active extracts using open column chromatography over silica gel and preparative thin layer chromatography purification, two terpenoid derived compounds, trans-phytol palmitate and γ-tocopherol were isolated from the dichloromethane and ethyl acetate extracts. The structures of the compounds were elucidated using different spectral data including 1H NMR, 13C NMR, HSQC, HMBC and EI-MS. The IC50 values of compounds trans-phytol palmitate, γ-tocopherol and an undetermined mixture of compounds (F-13-14) were determined as 43.4 ± 1.6, – and 20.3 ± 6.2 µg/ml against LS180 (human colon adenocarcinoma); 53.2 ± 9.3, >100 and 27.6 ± 6.9 µg/ml against MCF-7 (human breast adenocarcinoma) and 40.0 ± 4.1, 48.8 ± 1.8 and 15.9 ± 0.3 µg/ml against MOLT-4 cell lines, respectively, which were comparable to the IC50 values of standard anticancer agent, cisplatin against the same cell lines. The red algae collected from the Persian Gulf contained substances that could inhibit the growth of human cancer cell lines and may represent a natural source for the discovery of novel anticancer agents.

Anti-inflammatory and antinociceptive activities of methanolic extract from red seaweed Dichotomaria obtusata

The aim of the present work was to investigate the anti-inflammatory and antinociceptive effects of methanolic extract from D. obtusata using classic models in mice (croton oil-induced ear edema and acetic acid-induced writhing) and a phospholipase A2 activity test. Qualitative analysis of the chemical composition of seaweed was also determined by extraction with solvents of increasing polarity and precipitation and color tests. Results of qualitative chemical study showed the presence of lactonic and phenolic compounds, reduced carbohydrates, other sugars, flavonoids, fatty compounds, triterpenes and steroids. The extract inhibited mouse ear edema in a dose-dependent manner with an efficacy higher than 90% and a mean effective dose of 4.87µg/ear, while intraperitoneal administration presented a moderate activity. The extract did not inhibit phospholipase A2 activity. In the writhing test, the intraperitoneal administration of the extract showed a strong antinociceptive activity (80.2%), while the oral route showed a lower efficacy. In conclusion, this study demonstrated the anti-inflammatory and antinociceptive effects of methanol extract of D. obtusata in experimental models, suggesting its therapeutic potential in the treatment of peripheral painful and/or inflammatory pathologies.

O objetivo do presente trabalho foi investigar os efeitos antiinflamatórios e antinociceptivos de um extrato metanólico de D. obtusata, utilizando modelos clássicos em ratos (teste do edema de orelha induzido por óleo de cróton e teste de contorções induzidas por ácido acético) e um teste de atividade de fosfolipase A2. A análise qualitativa da composição química das algas foi também determinada através de extração com solventes de polaridade crescente e testes de precipitação e cor. Os resultados do estudo de química qualitativa mostraram a presença de compostos lactônicos e fenólicos, hidratos de carbono reduzidos e outros açúcares, flavonoides, compostos graxos, triterpenos e esteroides. O extrato inibiu o edema de orelha dos ratos de um modo dependente da dose com eficácia superior a 90% e dose média efetiva de 4.87µg/orelha, enquanto a administração intraperitoneal apresentou atividade moderada. O extrato não inibiu a atividade da fosfolipase A2. No teste de contorção, a administração intraperitoneal do extrato mostrou forte atividade antinociceptiva (80,2%), enquanto a administração oral mostrou menor eficácia. Em conclusão, este estudo demonstrou os efeitos antiinflamatórios e antinociceptivos do extrato metanólico de D. obtusata em modelos experimentais, sugerindo seu potencial terapêutico no tratamento de patologias dolorosas periféricas e/ou inflamatórias.

Anti-inflammatory and analgesic activities of red seaweed Dichotomaria obtusata / Atividades anti-inflamatória e analgésica da alga marinha vermelha Dichotomaria obtusata

The aim of the present work was to investigate the anti-inflammatory and analgesic effects of red seaweed Dichotomaria obtusata, using classic tests in mice (ear edema induced by TPA and writhing induced by acetic acid). The qualitative chemical composition of the aqueous extract (lactones, phenols, triterpenes, steroids and reduced carbohydrates) obtained from this alga was also determined. The results showed that Dichotomaria obtusata (12.5, 25 and 50 mg/kg, ip) inhibited mouse ear edema in a dose-dependent manner. In the writhing test, aqueous extract (12.5, 25, 50 and 100 mg/kg, ip and 100, 200, 400, 800 mg/kg, po) significantly reduced abdominal writhes. In conclusion, this study demonstrated the anti-inflammatory and antinociceptive activities of aqueous extract of D. Obtusata in experimental models. These results suggest that D. obtusata aqueous extract possesses therapeutic potential in the treatment of peripheral painful or/and inflammatory conditions.

O objetivo do presente trabalho é centrado nos efeitos antiinflamatórios e analgésicos da alga vermelha Dichotomaria obtusata por meio de clássicos testes em camundongos (edema de orelha induzido por TPA e contorção induzida por ácido acético). Também foi determinada a composição química qualitativa do extrato (lactonas, fenóis, triterpenos, esteróides e carboidratos reduzidos). Os resultados mostraram que de Dichotomaria obtusata (12,5, 25 e 50 mg/kg, ip) inibiu o edema de orelha do camundongo de forma dose-dependente. No teste de contorção, extrato aquoso (12,5, 25, 50 e 100 mg/kg, ip e 100, 200, 400, 800 mg/kg, po) reduziu o contorções abdominais de forma significativa. Em conclusão, o estudo demonstrou a atividades antiinflamatória e antinociceptiva do extrato aquoso em modelos experimentais. Estes resultados sugerem que o extrato aquoso D.obtusata possuem potencial terapêutico no tratamento de dor periférica e/ou de doenças inflamatórias.

The status of the name Alysium holtingii C. Agardh, a red alga described from Brazil, and a depiction of the type specimen

The type specimen of the red alga Alysium holtingii C. Agardh, described from Brazil, is located in the Lund Herbarium, and it is depicted for the first time in a publication. It is taxonomically identical to Dichotomaria obtusata (J. Ellis and Solander) Lamarck and thus can be treated as a later taxonomic synonym. Alysium is regarded as congeneric with Dichotomaria.

O espécime tipo da alga vermelha Alysium holtingii C. Agardh, descrito para o Brasil, está localizado no Herbário Lund, e é aqui apresentado. Ele é taxonomicamente idêntico a Dichotomaria obtusata (J. Ellis e Solander) Lamarck e portanto deve ser tratado como um sinônimo taxonômico posterior. Alysium é considerado como congenérico com Dichotomaria.