br Materials and methods br Results Dried leaves used

Materials and methods
Results Dried iso 1 used were 48.46 g C. benghalensis, 857.98 g T. zebrina and 25.09 g T. fluminensis. The samples gave 12.9% C. benghalensis, 0.078% T. zebrina and 3.06% T. fluminensis methanol extracts. The methanol extracts were evaluated for their lipoxygenase inhibitory activity as shown in Table 1. All extracts showed significant inhibition with T. fluminensis exhibiting the highest activity at 87.18%. The methanol extracts were then qualitatively tested for the various phytochemicals they contain. As shown in Table 2, T. zebrina was tested positive for the presence of saponins, phenolic compounds and flavonoids tests, while C. benghalensis showed the presence of terpenoids and flavonoids tests and T. fluminensis to the flavonoids and steroids tests. The plant sample with the highest inhibitory activity was then partitioned using distilled hexane and ethyl acetate. The percentage yields were 1.03% hexane extract and 1.08% ethyl acetate extract. The resulting extracts were then evaluated for their lipoxygenase activity as shown in Table 3. The ethyl acetate extract exhibited higher activity at 87% than the hexane extract at 56%. This may be due to the different phytochemicals they contain. The ethyl acetate and hexane fractions of T. fluminensis were positive for the presence of flavonoids. For better comparison as to which extract had a more potent inhibitory activity against the 15-lipoxygenase enzyme, the IC50 was obtained for each fraction. The IC50 for the hexane fraction was determined to be 98.04 μg/mL while the ethyl acetate fraction was 8.72 μg/mL, indicating a more potent and better inhibitory action.
Discussion C. benghalensis, T. fluminensis and T. zebrina methanol leaf extracts gave significant lipoxygenase inhibition. The three extracts showed positive results for the presence of flavonoids. Flavonoids are polyphenolic compounds with a flavones structure of two benzene rings joined by a γ-pyrone ring. The structure has several variations of substitution and there are now 4000 characterized flavonoids[29]. They possess a wide spectrum of bioactivity and they inhibit a number of enzymes[30]. Flavonoids have been shown to inhibit lipoxygenase activity and the presence of such constituents may be responsible for the inhibitory activity of the extracts[31]. T. fluminensis methanol extract showed the highest inhibitory activity at 87.18%. Its ethyl acetate fraction gave higher inhibitory activity at 87.40% than its hexane fraction at 56.00%. It is possible that the flavonoids present in the ethyl acetate fraction have higher lipoxygenase inhibitory action and may contain planar structures. The structure-activity relationship of similar flavonoids quercetin, luteloin, catechin and taxifolin have been investigated. Quercetin and luteloin showed superior inhibitory activity over catechin and taxifolin because of the planarity of the molecules[12]. The IC50 of the ethyl acetate fraction of T. fluminensis was determined to be 8.72 μg/mL while that of Cassia alata extract was 90.2 μg/mL[18], indicating a more potent and better inhibitory action for the former. There are few literatures that deal with the study of the phytochemical constituents of the Commelinaceae family. The most common phytochemical constituents studied were the glycoflavones, flavonols, and phenolic acids[32]. Another recent study for the phytochemical constituents of Commelinaceae is that of Ogbebor and Edeoga[33]. Based on their study, alkaloids and saponins are present in a species under the said family. In comparison with the results, some constituents did not exhibit a positive result which may be due to insufficient amount of the active compounds present in concentration used in the tests. Another cause may be the presence of interfering compounds thus producing negative results[34].
Conflict of interest statement
Acknowledgements