Synthesis and evaluation of coumarin derivatives on antioxidative, tyrosinase inhibitory activities, melanogenesis, and in silico investigations

New coumarin derivatives were designed using a 2-(2-oxo-2H-chromen-4-yl)acetic acid scaffold conjugated with amino acid esters or tyramine. The anti-tyrosinase and anti-lipid peroxidation activities of the synthesized compounds were investigated. Coumarin derivatives 7,9, 11-13, 15-18 showed strong anti-lipid peroxidation activity. Compound 13 exhibited uncompetitive tyrosinase inhibitory activity with an IC50 value of 68.86 µM. Compound 14 (% activity = 123.41) showed stronger tyrosinase activating activity than 8-methoxypsolaren (8-MOP, % activity = 109.46). In silico studies revealed different poses between the inhibitors and activators near the tyrosinase catalytic site. Compounds 13 (25-50 μM) and 14 (25-100 μM) did not show cytotoxicity against B16F10 cells. In contrast to the tyrosinase inhibition assay, compound 13 (50 μM) suppressed melanogenesis in B16F10 cells with two times higher potency than KA (100 μM). Compound 14 at 100 μM showed melanogenesis enhancement in B16F10 cells in a dose-dependent manner, however, inferior to the 8-MOP. Based on the findings, compound 13 and 14 offer potential for development as skin-lightening agents and vitiligo therapy agents, respectively.

Effect of Piper betle extract on anti-candidal activity, gelation time, and surface hardness of a short-term soft lining material

The purpose of this study was to evaluate anti-candidal activity, gelation time, and surface hardness of a short-term soft lining material incorporated with varying concentrations of Piper betle extract (0.25 to 20% w/w). Agar-diffusion assay was conducted to evaluate an inhibitory effect against Candida albicans. The gelation time was assessed and surface hardness was measured at 2 h and 7 days by Shore AO durometer. A soft liner containing at least 5% w/w of P. betle extract was observed the inhibitory effect against C. albicans. An increasing of P. betle concentrations provided larger inhibition zone. Incorporating 5% w/w of P. betle extract into the soft liner did not significantly alter its gelation time and surface hardness (ANOVA; p>0.05). The optimum composition at 5% w/w of P. betle extract can be used as an additive in the soft liner to provide the anti-candidal activity without significantly affect these two main properties.

Synthesis of 2-(2-oxo-2H-chromen-4-yl)acetamides as potent acetylcholinesterase inhibitors and molecular insights into binding interactions

Sixteen novel coumarin-based compounds are reported as potent acetylcholinesterase (AChE) inhibitors. The most active compound in this series, 5a (IC₅₀ 0.04 ± 0.01 µM), noncompetitively inhibited AChE with a higher potency than tacrine and galantamine. Compounds 5d, 5j, and 5 m showed a moderate antilipid peroxidation activity. The compounds showed cytotoxicity in the same range as the standard drugs in HEK-293 cells. Molecular docking demonstrated that 5a acted as a dual binding site inhibitor. The coumarin moiety occupied the peripheral anionic site and showed π-π interaction with Trp278. The tertiary amino group displayed significant cation-π interaction with Phe329. The aromatic group showed π-π interaction with Trp83 at the catalytic anionic site. The long chain of methylene lay along the gorge interacting with Phe330 via hydrophobic interaction. Molecular docking was applied to postulate the selectivity toward AChE of 5a in comparison with donepezil and tacrine. Structural insights into the selectivity of the coumarin derivatives toward huAChE were explored by molecular docking and 3D QSAR and molecular dynamics simulation for 20 ns. ADMET analysis suggested that the 2-(2-oxo-2H-chromen-4-yl)acetamides showed a good pharmacokinetic profile and no hepatotoxicity. These coumarin derivatives showed high potential for further development as anti-Alzheimer agents.

Anti-HIV-1 integrase effect of compounds from Aglaia andamanica leaves and molecular docking study with acute toxicity test in mice

CONTEXT

Acquired immunodeficiency syndrome (AIDS) is a serious health problem worldwide. It has been reported that Aglaia andamanica Hiern (Meliaceae) leaves possessed an antiviral effect. Therefore, a search of anti-HIV-1 integrase (HIV-1 IN) agents from A. andamanica is a promising target.

OBJECTIVE

The objective of this study is to evaluate anti-HIV-1 IN activity of isolated compounds from A. andamanica using an in vitro assay and molecular docking study as well as testing acute toxicity in mice using the up and down method.

MATERIALS AND METHODS

The leaves and compounds (3-100 μg/mL) from A. andamanica were determined for the anti-HIV-1 IN effect using the multiplate integration assay (MIA) by detection the absorbance of the final product, p-nitrophenol, at 405 nm. The molecular docking with the HIV-1 IN of the active compound N-methyl-trans-4-hydroxy-l-proline (10) was also studied. The Swiss albino mice were used for an acute toxicity test.

RESULTS AND DISCUSSION

Among the isolated compounds, 10 showed marked anti-HIV-1 IN effect with an IC50 value of 11.8 μg/mL, whereas other compounds were inactive (IC50 value > 100 μg/mL). The molecular docking of compound 10 with an HIV-1 IN enzyme was also studied. The result revealed that this compound formed the hydrogen bonding with the Thr66, Asn155, and Lys159 of the HIV-1 IN binding site. The acute toxicity of the A. andamanica extract was not observed at the dose 2000 mg/kg mice. This is the first report of A. andamanica for anti-HIV-1 IN activity.

Effectiveness of Artocarpus lakoocha extract, poloxamer 407, on Enterococcus faecalis in vitro

AIM

The antiviral activities of Artocarpus lakoocha (A. lakoocha) extract have been reported in a number of studies; however, data regarding its antibacterial capability are limited. The aim of the present study was to examine the effectiveness of A. lakoocha extract, poloxamer 407, on Enterococcus faecalis (E. faecalis).

METHODS

The effect of the antimicrobial activity of A. lakoocha extract and A. lakoocha extract, poloxamer 407, against E. faecalis was investigated. The antibacterial efficacy of A. lakoocha extract, poloxamer 407, against E. faecalis was compared to calcium hydroxide in a tooth model.

RESULTS

The minimal inhibitory concentration and minimal bactericidal concentration (MBC) of A. lakoocha extract against E. faecalis were 0.39 ± 0 mg/mL and 3.12 ± 0 mg/mL, respectively; the MBC of calcium hydroxide against E. faecalis was 31.25 ± 0 mg/mL. In the tooth model, the E. faecalis count in all groups significantly decreased as the depth into the dentin increased compared to the control. There were no significant differences between 4% A. lakoocha extract poloxamer and UltraCal XS at any time period (P > 0.05) with one exception: at a depth of 0.6 mm on day 5, UltraCal XS had a significantly greater colonization than 4% A. lakoocha extract poloxamer.

CONCLUSION

A. lakoocha extract, poloxamer 407, might be a useful alternative for antimicrobial medication in endodontic treatment. However, controlled clinical studies to evaluate its efficacy are needed.

Phytochemical investigation of Aglaia andamanica

Four new compounds, the limonoid 24-epi-melianodiol (8), the tirucallane aglaiodiol (9), and the two cyclopentatetrahydrobenzopyran derivatives pyramidaglain A (11) and B (12) were isolated from the leaves of Aglaia andamanica Hiern (Meliaceae), together with the eleven known constituents beta-sitosterol, beta-sitosterol glucoside, cycloart-23E-ene-3 beta,25-diol (1), three flavonoids 5-hydroxy-3,4',7-trimethoxyflavone (2), retusin (3) and pachypodol (4), the tirucallane 24-epi-piscidinol A (5), the lignan yangambin (6), the limonoid melianodiol (7), the bisamide pyramidatine (10) and the amino acid N-methyl-trans-4-hydroxy-L-proline (13). All structures were established by means of detailed spectroscopic analysis.

Phytochemical investigation of Aglaia rubiginosa

The phytochemical investigation of a methanolic leaf extract of Aglaia rubiginosa furnished 15 isoprenoid constituents, eight of which represented new natural entities. Two androstane derivatives (1 and 2), previously synthesized, and also obtained by microbiological transformations; an extraordinary 17-octanor-cycloartane-ring-A-seco acid (3); four cycloartane-type triterpenes (4-7); and three unusual cholesterol derivatives (8-10) were isolated, along with two known dammaranes (11 and 12), a stigmastandiol (13), and beta-sitosterol and its beta-D-glucoside. Spectroscopic structure elucidation of the new natural products (1-3, 6, 7, 8-10) is described.

Bisamides from Aglaia species: structure analysis and potential to reverse drug resistance with cultured cells

The structure of pyramidatine [1], a new bisamide alkaloid from leaves of Aglaia pyramidata, was determined through extensive nmr studies, including homonuclear COSY, NOESY, APT, HETCOR, and selective INEPT techniques. Revision of the 13C-nmr assignment of piriferine [2], an alkaloid previously isolated from A. pirifera, was achieved by examination of several 2D nmr spectra (homonuclear COSY, NOESY, and HETCOR) and confirmed by selective INEPT nmr experiments. Evaluation of the cytotoxic potential of the two alkaloids, along with two other bisamides from Aglaia odorata, odorine [3] and 5'-epi-odorine [4], was carried out in eleven human cancer cell lines. None of these bisamides showed significant cytotoxicity. Nevertheless, piriferine [2], odorine [3], and 5'-epi-odorine [4] were found to inhibit the growth of the vinblastine-resistant KB cells by enhancing the anticancer activity of vinblastine.