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Ethanol and aqueous extracts of the different parts of Piper sarmentosum were analysed by HPLC for marker compounds to standardise these extracts. The standardised extracts were investigated for antioxidant activity (beta-carotene linoleate model and DPPH model), anti-TB activity (microplate tetrazolium assay), and estimation of total phenolic and amide contents. The extracts of the different parts exhibited different antioxidant activity, phenolic and amide contents (p < 0.01). The ethanol extracts exhibited better antioxidant activity as compared to the aqueous extracts. The leaf ethanol extract was further investigated for dose response relationship and its EC(50) was found to be 38 microg mL(-1). All the extracts have exhibited anti-TB activity with MIC/MBC 12.5 microg mL(-1). The leaf methanol extract was fractionated and the ethyl acetate fraction exhibited anti-TB activity with MIC/MBC 3.12 microg mL(-1) while MIC/MBC of isoniazid (INH) was found to be 0.5 microg mL(-1). A positive correlation was found between antioxidant activity and total polyphenols, flavonoids and amides, in the beta-carotene linoleate model (p = 0.05) and in the DPPH model (p = 0.01). The analytical method was found to have linearity >0.9922, coefficient of variance <5% and accuracy 95.5 +/- 5 to 96.9 +/- 5. This plant possesses promising antioxidant as well as anti-TB properties.

In vitro assays are economical and easy to perform but to establish relevance of their results to real clinical outcome in animals or human, pharmacokinetics is prerequisite. Despite various in vitro pharmacological activities of extracts of Piper sarmentosum, there is no report of pharmacokinetics. Therefore, the present study aimed to evaluate ethanol extract of fruit of the plant in dose of 500 mg kg−1 orally for pharmacokinetics. Sprague-Dawley rats were randomly divided into groups 1, 2, and 3 (each n = 6) to study absorption, distribution and excretion, respectively. High performance liquid chromatography (HPLC) with ultraviolet detection was applied to quantify pellitorine, sarmentine and sarmentosine in plasma, tissues, feces and urine to calculate pharmacokinetic parameters. Pellitorine exhibited maximum plasma concentration (C max) 34.77 ng mL−1 ± 1.040, time to achieve C max (T max) 8 h, mean resident time (MRT) 26.00 ± 0.149 h and half life (t 1/2) 18.64 ± 1.65 h. Sarmentine showed C max 191.50 ± 12.69 ng mL−1, T max 6 h, MRT 11.12 ± 0.44 h and t 1/2 10.30 ± 1.98 h. Sarmentosine exhibited zero oral bioavailability because it was neither detected in plasma nor in tissues, and in urine. Pellitorine was found to be distributed in intestinal wall, liver, lungs, kidney, and heart, whereas sarmentine was found only in intestinal wall and heart. The cumulative excretion of pellitorine, sarmentine and sarmentosine in feces in 72 h was 0.0773, 0.976, and 0.438 μg, respectively. This study shows that pellitorine and sarmentine have good oral bioavailability while sarmentosine is not absorbed from the gastrointestinal tract.

In the title compound, C21H19N3O3, the pyridine ring forms a dihedral angle of 15.25 (6)° with the benzene ring. The dihedral angle between the two benzene rings is 83.66 (7)°. The meth­oxy group is slightly twisted away from the attached ring [C—O—C—C = 7.5 (2)°]. In the crystal structure, mol­ecules are linked into a three-dimensional network by inter­molecular N—H⋯N and C—H⋯O hydrogen bonds. The structure is further stabilized by C—H⋯π inter­actions.

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