Hibiscus species (Malvaceae) have been long used as an antihypertensive folk remedy. The aim of our study was to specify the optimum solvent for extraction of the angiotensin-converting enzyme inhibiting (ACEI) constituents from Hibiscus sabdariffa L. The 80% methanol extract (H2) showed the highest ACEI activity, which exceeds that of the standard captopril (IC50 0.01255 ± 0.00343 and 0.210 ± 0.005 µg/mL, respectively). Additionally, in a comprehensive metabolomics approach, an ultra-performance liquid chromatography (UPLC) coupled to the high resolution tandem mass spectrometry (HRMS) method was used to trace the metabolites from each extraction method. Interestingly, our comprehensive analysis showed that the 80% methanol extract was predominated with secondary metabolites from all classes including flavonoids, anthocyanins, phenolic and organic acids. Among the detected metabolites, phenolic acids such as ferulic and chlorogenic acids, organic acids such as citrate derivatives and flavonoids such as kaempferol have been positively correlated to the antihypertensive potential. These results indicates that these compounds may significantly contribute synergistically to the ACE inhibitory activity of the 80% methanol extract.

Morinda citrifolia L. is a plant of the family Rubiaceae and is known as Indian mulberry or Noni in India. It is a perennial herb native to Southeast Asia and has been used over the years as a food supplement and medicinal plant. Noni fruits are reported to possess anticancer, fungicidal, antiviral and antiarthritic effects. The objective of our study is the screening of the immunomodulatory activity of the total extract, fractions, and isolated compounds of Noni fruits to identify their bioactive compounds. To achieve our goal, an ethanol extract (EE) was prepared from Noni fruits. Fractionation and purification of the EE were accomplished. The cell-mediated immune (CMI) response in prednisolone-induced immunosuppression rats was evaluated. The toxicity of the EE, fractions and isolated compounds on the differentiated THP-1 macrophage was assessed using the MTT viability assay. Moreover, the inflammation-related immune responses in lipopolysaccharide (LPS)-induced THP-1 macrophage activation were evaluated. Fractionation of the EE gave three fractions, dichloromethane (DCMF), water (WF) and methanol (MF). Purification of DCMF yielded stigmast-7-ene-3-ol (M1), 28-hydroxy-3β-acetoxy-9-dehydrogramisterol (M2), 3β-acetoxy-taraxast-20(30)-ene-21-ol (M3), 22-dehydroclerosterol (M4) and 22-dehydroclerosterol-3-O-β-D-glucopyranoside (M5), while purification of MF yielded quercetin (M6), hesperidin (M7), naringin (M9) and gallic acid (M8). The results revealed that DCMF elicited an increase in paw edema to the extent of 35.8%. All the tested samples had no cytotoxic effect on THP-1 macrophages. Co-treatment of the LPS-induced macrophages with DCMF, M2, M3, and M6 decreased the production of TNF-α, IL-1β, and IL-6/IL-10. The expression of iNOS, COX-2, and NF-κB decreased to 0.14 ± 0.02, 0.15 ± 0.02, and 0.17 ± 0.03, respectively, after co-treatment with LPS and DCMF. M2 attenuated the expression of iNOS and NF-κB to 0.18 ± 0.03 and 0.17 ± 0.03, respectively. Additionally, M3 attenuated the expression of iNOS to 0.18 ± 0.03, and after co-treatment with M6 and LPS, the expression of COX-2 and NF-κB was down-regulated to 0.2 ± 0.03. Our study proves the immunomodulatory effect of Noni fruits and specifies for the first time the compounds responsible for their activity.

Phyllanthin and related lignans were found to be responsible, at least in part, for most of the activity of Phyllanthus species. This observation encouraged the authors to develop methods for the preparation of an extract rich in phyllanthin and related lignans from the aerial parts of P. niruri L. Direct extraction with solvents produced extracts with variable yields and contents of lignans. Lignans were identified by LC-ESI-MS analysis as phyllanthin (used as marker substance), hypophyllanthin, phylltetralin, nirtetralin, and niranthin. Extraction with boiling water produced 18.10 g% (w/w) extract with a trace amount of lignans (phyllanthin content of 0.33 ± 0.10 mg/g extract), while extraction with MeOH gave 3.6 g% w/w extract with a low phyllanthin content (3.1 mg/g extract), as determined by HPLC. However, Soxhlet extraction with hexane, CH₂Cl₂, or acetone gave extracts with low yields (0.82, 1.12, and 3.40 g% w/w, respectively) and a higher phyllanthin contents (36.2 ± 2.6, 11.7 ± 1.68, and 11.7 ± 1.10 mg/g extract, respectively). Extraction quality and efficiency were optimized by adopting the following three different approaches: (1) Alkaline digestion of the plant material with 30% potassium hydroxide yielded 3.1 g% w/w of purified extract with high phyllanthin content (22.34 ± 0.13 mg/g); (2) microwave-assisted extraction using 80% MeOH gave an extract with a better yield (8.13 g% w/w) and phyllanthin content (21.2 ± 1.30 mg/g) (after filtration through a Diaion HP-20 column); and (3) treatment of the ground plant material at 50 °C with two hydrolytic enzymes, cellulase (9 U/g for 12 h) and then, protease (4 U/g up to 72 h) optimized the yield of extract (13.92 g% w/w) and phyllanthin content (25.9 mg/g extract and total lignans content of 85.87 mg/g extract). In conclusion, the nonconventional methods presented here are superior for optimizing the yield of extract and its lignan contents from the aerial parts of P. niruri.