Synergistic effect of ampicillin and dihydrobenzofuran neolignans (myticaganal C) identified from the seeds of Myristica fragrans Houtt. against Escherichia coli.

The present study was designed to enhance the antibacterial activity of ampicillin against Escherichia coli by combining it with myticaganal C. Antibacterial activity of ampicillin combined with myticaganal C against E. coli was assessed by agar well diffusion. Minimum inhibitory concentrations (MICs) and synergy by checkerboard assay of ampicillin and myticaganal C were assessed by resazurin-based 96-well microdilution. Bacterial responses were assessed by flow cytometry. Ampicillin in combination with myticaganal C showed better zone of inhibition (31.67 ± 0.58 mm) than myticaganal C or ampicillin alone. MIC of ampicillin was found to be 12.5 µg/mL, but myticaganal C was ineffective against E. coli. Myticaganal C (8000 µg/mL) with ampicillin (0.0975 µg/mL) exhibited strong synergy, so the need for ampicillin was reduced 128-fold. Combination inhibited E. coli by acting on cell membrane and by granularity disruptions. These findings indicate that myticaganal C enhances the potential of ampicillin against E. coli, thus providing an effective alternative to deal with the problem of bacterial resistance.

New neolignans from the seeds of Myristica fragrans and their cytotoxic activities.

Three new dihydrobenzofuran neolignans, myticaganal A-C (1-3), along with five known compounds (4-8), were isolated from the seeds of Myristica fragrans. Their structures were elucidated by extensive spectroscopic analysis. In vitro cytotoxic activities of the isolated compounds against three human cancer cell lines (KB, oral cavity; MCF-7, breast cancer; and NCI-H187, small cell lung cancer) were evaluated. Neolignan 3 showed significant cytotoxicity against KB and NCI-H187 cell lines with IC50 values of 5.9 and 6.3 µM, respectively.

Two new antimalarial quassinoid derivatives from the stems of Brucea javanica.

Phytochemical investigation of the stems from Brucea javanica led to the isolation of two new quassinoids, brujavanol C (1) and brujavanol D (2), together with six known compounds (3-8). The chemical structures were elucidated by means of various spectroscopic methods. All the isolated compounds were evaluated for antimalarial activity against Plasmodium falciparum and compounds 6 and 7 exhibited the most potent activity against the K1 strain, with IC50 values of 1.41 and 1.06 µM, respectively.

Antimalarial and cytotoxic quassinoids from the roots of Brucea javanica.

Two new quassinoids, brujavanol A (1) and brujavanol B (2), along with five known quassinoids (3-7), were isolated from the roots of Brucea javanica. Their structures were elucidated by spectroscopic methods. The antimalarial and cytotoxic activities of the isolated compounds were also assessed. Compounds 1 and 2 exhibited significant in vitro cytotoxicity against human oral cavity cancer (KB) cells with IC50 values of 1.30 and 2.36 µg/ml, respectively, whereas compound 3 showed excellent antiplasmodial activity against the Plasmodium falciparum strains, K1 (IC50 = 0.58 µg/ml).

New cytotoxic steroids from the fruits of Syzygium siamense.

A new sterol, stigmast-5-ene-3beta,17alpha-diol (1), together with six known compounds, stigmast-5-ene-3beta-yl formate (2), stigmast-5-ene-3beta,7alpha-diol (3), stigmast-5-ene-7alpha-methoxy-3beta-ol (4), stigmast-5-ene-3-one (5), 3beta-sitostanol (6), and 3beta-sitosterol (7), was isolated from the fruits of Syzygium siamense, of which compound 2 is reported for the first time from a natural source. Their structures were elucidated by spectroscopic methods. The isolated compounds (1-7) were evaluated for their cytotoxic activities against human oral epidermoid carcinoma cancer (KB), human breast cancer (BC), and human small cell lung cancer (NCI-H187) cell lines.

Potent cytotoxic rocaglamide derivatives from the fruits of Amoora cucullata.

Two new rocaglamide derivatives, 1-O-formylrocagloic acid (1) and 3'-hydroxy rocagloic acid (2), together with five known compounds, rocaglaol (3), rocagloic acid (4), 3'-hydroxymethylrocaglate (5), 1-O-formylmethyl rocaglate (6), and methylrocaglate (7), were isolated from the fruits of Amoora cucullata. Their structures were elucidated by spectroscopic methods. Compounds 1-3, 6, and 7 exhibited potent cytotoxicity against KB, BC, and NCI-H187 cell lines, whereas 4 and 5 showed selective cytotoxicity against NCI-H187 cell line.

A new triterpenoid ester from the fruits of Bruguiera parviflora.

A new lupane caffeoyl ester (1), 3-(Z)-caffeoyllupeol, together with five known triterpenoids, lupeol caffeate (2), 3-(Z)-coumaroyllupeol (3), dioslupecin A (4), lupeol (5), and lupenone (6), were isolated from the fruits of Bruguiera parviflora. Their structures were elucidated by spectroscopic methods. Compound 1 exhibited antimalarial activity with an EC50 value of 8.6 microg/ml, but compound 2 was inactive.

Antimycobacterial activity of phorbol esters from the fruits of Sapium indicum.

Three new phorbol esters, 12-(2-N-methylaminobenzoyl)-4beta,5,20-trideoxyphorbol-13-acetate (1), 12-(2-N-methylaminobenzoyl)-4alpha,5,20-trideoxyphorbol-13-acetate (2), and 12-(2-N-methylaminobenzoyl)-4alpha, 20-dideoxy-5-hydroxyphorbol-13-acetate (6), together with six known compounds (3-5 and 7-9), were isolated from the fruits of Sapium indicum. The chemical structures of 1, 2, and 6 were elucidated by analysis of their spectroscopic data. Compounds 1-3, 5, and 7-9 exhibited antimycobacterial activity with minimum inhibitory concentrations (MIC) between 3.12 and 200 microg/mL, but compounds 4 and 6 were inactive (MIC >200 microg/mL).