Phytochemical Analysis, Cytotoxicity, and Antitrypanosomal, Antioxidant, and Anti-Inflammatory Activities of Clausena anisata Fruit, Azadirachta indica Leaf, and Stem Bark Extracts

Human African trypanosomiasis (HAT) is an infectious disease which kills humans and animals as a result of hematological distortions, oxidative stress, tissue and neuroinflammations. This study reports on the differences in cytotoxicity, antitrypanosomal, antioxidant, and anti-inflammatory activities of ethanol extracts from Clausena anisata fruit (CFE), Azadirachta indica (neem) leaf (NLE), and stem bark (NSBE), medicinal plants used to treat HAT in its endemic communities. The extracts remarkably inhibited Trypanosoma brucei brucei (GUTat 3.1) parasite in vitro with CFE recording the highest effect with an IC50 of 0.0055 (0.0955) μg/mL. The IC50 of the standard Coptis japonicum was 0.5957 (0.0693) μg/mL. Also, the antitrypanosomal activity of NLE was 123.34% higher than that of NSBE. The percentage number of wells containing viable T. b. brucei parasites was very significantly (p < 0.001) reduced for all the extracts after 48 h of incubation. Furthermore, the extracts did not show cytotoxicity against the liver (HepG2) cells (CC50s > 100 μg/mL and SI = 13.12-32,025.45). NSBE contained the highest quantity of phenolic compounds and flavonoids and also produced the highest antioxidant and anti-inflammatory activity in the DPPH free radical scavenging assay (IC50 = 4.99 ± 0.018) and protein denaturation assay (IC50 = 0.1805 ± 0.0002 μg/mL). In addition, phytochemical analysis showed that NLE contained the highest number of classes of phytochemical constituents (seven) among the extracts. These results indicate that CFE, NLE, and NSBE possessed significant antitrypanosomal activity as a result of their antioxidant and anti-inflammatory actions. However, a different mechanism was also involved in the antitrypanosomal activity of CFE and NLE, since their antitrypanosomal activity is greater than NSBE which demonstrated the highest antioxidant and anti-inflammatory activities. Due to the remarkable antitrypanosomal action of CFE, its constituents are being isolated for possible development into novel antitrypanosomal agents.

Bio-Guided Isolation of Prospective Bioactive Constituents from Roots of Clausena indica (Dalzell) Oliv

Clausena indica fruits are routinely used for the culinary purpose as natural spices, whereas leaves and roots are folk medicine with various health benefits in southern China, South and Southeast Asia. In this study, the bioassay-guided fractionation by column chromatography yielded three pure compounds including dentatin, nordentatin, and clausine K and five active fractions (Re1-5) from C. indica roots. These known anticancer compounds were confirmed by X-ray diffraction, 1H-, 13C-nuclear magnetic resonance (NMR), and electrospray ionization tandem mass spectrometric (ESI-MS-MS) analyses. Meanwhile, the phytochemical constituents from fractions were identified by gas chromatography-mass spectrometry (GC-MS). The isolates, fractions' components and their biological activities were first time investigated on C. indica. By in vitro DPPH and ABTS scavenging assays, nordentatin (IC50 = 49.2 and 69.9 µg/mL, respectively) and the fraction Re4 (32.4 and 38.5 µg/mL, respectively) showed the strongest antiradical activities, whereas clausine K presented a moderate and dentatin had negligible antioxidant activity, respectively. The anti-α-amylase activity of C. indica root extracts was mainly attributed to the fraction Re2 which inactivated the enzymatic assay with IC50 of 573.8 µg/mL. Among tested samples, only nordentatin and clausine K were effective in the pancreatic elastase inhibition, however, their influences were trivial. Markedly, clausine K and Re4 performed the most remarkable tyrosinase inhibition with IC50 values of 179.5 and 243.8 µg/mL, respectively, which were in turn 4 and 3 times stronger than myricetin (IC50 = 735.6 µg/mL), a well-known tyrosinase inhibitor. This is the first report affirming clausine K to be a new strong tyrosinase inhibitor. Isolated compounds from C. indica roots were quantified by high-performance liquid chromatography (HPLC), of which, dentatin, nordentatin, and clausine K accounted for 14.74, 6.14, and 1.28 mg/g dry weight. The findings suggest that bioactive constituents from C. indica roots may be potentially employed for the development of antidiabetic, antiaging and cosmetic agents.