Christine L. Chichioco Hernandez

Solvent fractions and decoction of Eleusine indica leaves were tested for their ability to inhibit angiotensin-converting enzyme (ACE), an important component of the Renin-Angiotensin-Aldosterone System which is a critical regulator of arterial blood pressure. The ACE inhibitory activity of each fraction was measured by employing a colorimetric assay based on the hydrolysis of histidyl-hippuryl-leucine (HHL) by ACE. Preliminary assay results revealed that the ethyl acetate fraction exhibited the highest antihypertensive activity with a percent inhibition of 51.51%. This fraction was considered for further isolation using a bioassay-guided fractionation scheme.

Two resveratrol oligomers, a dimer (1) and a tetramer (2), were isolated from the ethyl acetate extracts of the leaves of Hopea acuminata along with vaticanol B, vaticaphenol A, vateriaphenol B, hopeaphenol, ε-viniferindiol, balanocarpol, and ampelopsin A. The structures of these compounds were established on the basis of spectroscopic data including two-dimentional nuclear magnetic resonance experiments. Compound 2, vaticanol B, vaticaphenol A, vateriaphenol B, hopeaphenol were found to inhibit protein splicing mediated by the Mycobacterium tuberculosis RecA intein in a nonspecific manner.

Context Ulcer is the most common gastrointestinal disturbance resulting from an inadequate gastric mucosal defense. Several drugs are available in the market to address the disease; however, these drugs are associated with unnecessary side effects. Objectives Previous research have confirmed the efficacy of plant extracts for possible treatment of the disease. This research aims to evaluate the anti-ulcer properties of medicinal plants. Methods Methanol extracts from the leaves of Intsia bijuga, Cynometra ramiflora, Tamarindus indica, Cassia javanica, Cassia fistula, Bauhini purpurea, Senna spectabilis, Senna siamea and Saraca thaipingensis were evaluated for their anti-ulcer activity using HCl-ethanol as ulcerogen. Results All extracts showed inhibitory activity with I. bijuga, T. indica, S. spectabilis and S. thaipingensis exhibiting more than 50% inhibition. S. thaipingensis showed the highest activity at 80%. S. spectabilis and S. thaipingensis were partitioned further into hexane, ethyl acetate and aqueous fractions. The aqueous and ethyl acetate fractions of S. spectabilis showed significant increased in its activity while the hexane and ethyl acetate fractions of S. thaipingensis gave higher activity than its aqueous portions. Conclusions We conclude that plant extracts are potential sources of new anti-ulcer agents.

To evaluate the 15-lipoxygenase inhibitory activity of the methanol leaf extracts of Commelina benghalensis, Tradescantia fluminensis (T. fluminensis) and Tradescantia zebrina. The inhibitory activity was evaluated using a spectrophotometric assay by observing the increase in absorbance at 234 nm due to the formation of the product 13-hydroperoxyoctadecadienoic acid. The extracts were also tested for the presence of terpenoids, saponins, tannins, flavonoids, steroids, phenolic compounds, alkaloids and cardiac glycosides. All the extracts inhibited the action of 15-lipoxygenase at a concentration of 0.2 µg/mL. T. fluminensis and Tradescantia zebrina exhibited higher than 50% inhibition with T. fluminensis at 87.2%. T. fluminensis was partitioned with ethyl acetate and hexane and their IC50 values were determined at 8.72 µg/mL and 98.04 µg/mL, respectively. T. fluminensis is a potentially good source of 15-lipoxygenase inhibitors.

Background: Antigonon leptopus Hook. and Arn., Polygonaceae (cadena de amor), is a herbal remedy for pain and gout-like symptoms in the Philippines. The methanol extract of A. leptopus have shown strong inhibitory action against xanthine oxidase. Objective: To isolate and identify the compound responsible for the xanthine oxidase inhibitory action. Materials and Methods: A bioassay-guided isolation scheme using an in vitro assay for the inhibition of xanthine oxidase was employed. The structure was established using spectroscopic analysis and chemical methods. Results: The isolated compound was determined to be a noncompetitive inhibitor of xanthine with an IC50 of 1.79 μg/mL. Conclusion: The isolated compound may represent a new class of xanthine oxidase inhibitors.