Leaf lipidome and transcriptome profiling of Portulaca oleracea: characterization of lysophosphatidylcholine acyltransferase

Phytochemical Characteristics and Anti-Inflammatory, Immunoregulatory, and Antioxidant Effects of Portulaca oleracea L.: A Comprehensive Review

Portulaca oleracea L. (P. oleracea) or purslane is a plant from the Portulacaceae family, which is used as food and traditional medicine for various diseases. This review article provides comprehensive information on the antioxidant, immunomodulatory, and anti-inflammatory properties of P. oleracea and its constituents. The literature survey of the different databases until the end of June 2023 was explored based on the keywords including the "P. oleracea, purslane, anti-inflammatory, immunomodulatory, and antioxidant properties." The plant contains flavonoids, alkaloids, terpenoids, fatty acids, vitamins, minerals, and some other compounds. The results indicated that P. oleracea and its constituents showed anti-inflammatory and immunomodulatory properties through reduction of inflammatory mediators including interferon gama (IFN-γ), interleukin (IL)-10, IL-4, tumor necrosis factor-alpha (TNF-α), and nitric oxide. Improvement in cytokines' serum levels (IFN-γ, IL-10, and IL-4) and increased IgG and IgM serum levels, as well as reduction of IgE, phospholipase A2, and total protein were demonstrated for P. oleracea. The plant and its constituents also improved oxidative stress by reduction of oxidant and increase of antioxidant markers. P. oleracea could be considered as an effective remedy for various inflammatory and immune diseases.

Portulaca oleracea, a rich source of polar lipids: Chemical profile by LC-ESI/LTQOrbitrap/MS/MSn and in vitro preliminary anti-inflammatory activity

Considering the ongoing interest in foods rich in nutrients like polyunsaturated fatty acids and bioactive polar lipids, the chemical and biological investigation of Portulaca oleracea (purslane), a herbaceous plant typically appreciated in Mediterranean and Asiatic diet, was carried out. The LC-ESI/HRMS/MSⁿ analysis of extracts and lipid enriched fractions of purslane edible parts provided a comprehensive polar lipid profile, ranging from linear and cyclic oxylipins to high molecular weight lipids including glycolipids, phospholipids and sphingolipids. The evaluation of the anti-inflammatory potential by in vitro reporter gene assays highlighted the ability of purslane lipid enriched fractions, at a concentration of 20 µg/ml, to inhibit the TNF-α-stimulated NF-kB pathway by 30-40% and to activate PPAR-ɣ and Nrf2 transcription factors to the same extent or more than the positive control, respectively. Altogether, these results encourage to revalue purslane in human nutrition as a source of bioactive polar lipids.

A review on bioactive phytochemicals and ethnopharmacological potential of purslane (Portulaca oleracea L.)

The Portulaca oleracea L. commonly known as purslane is distributed all over the world and easily grows in diverse soil and climatic conditions. It has been traditionally used as a nutritious and ethnomedicinal food across the globe. Various studies have shown that the plant is a rich source of various important phytochemicals such as flavonoids, alkaloids, terpenoids, proteins, carbohydrates, and vitamins such as A, C, E, and B, carotenoids and minerals such as phosphorus, calcium, magnesium and zinc. It is particularly very important because of the presence of a very high concentration of omega-3- fatty acids especially α-linolenic acid, gamma-linolenic acid and linoleic acid, which are not generally synthesized in terrestrial plants. Various parts of purslane are known for ethnomedicinal and pharmacological uses because of its anti-inflammatory, antidiabetic, skeletal muscle relaxant, antitumor, hepatoprotective, anticancer, antioxidant, anti-insomnia, analgesic, gastroprotective, neuroprotective, wound healing and antiseptic activities. Due to multiple benefits of purslane, it has become an important wonder crop and various scientists across the globe have shown much interest in it as a healthy food for the future. In this review, we provide an update on the phytochemical and nutritional composition of purslane, its usage as nutritional and an ethnomedicinal plant across the world. We further provide a detailed account on ethnopharmacological studies that have proved the ethnomedicinal properties of purslane.

Recycling of the major thylakoid lipid MGDG and its role in lipid homeostasis in Chlamydomonas reinhardtii

Monogalactosyldiacylglycerol (MGDG), the most abundant lipid in thylakoid membranes, is involved in photosynthesis and chloroplast development. MGDG lipase has an important role in lipid remodeling in Chlamydomonas reinhardtii. However, the process related to turnover of the lysogalactolipid that results from MGDG degradation, monogalactosylmonoacylglycerol (MGMG), remains to be clarified. Here we identified a homolog of Arabidopsis thaliana lysophosphatidylcholine acyltransferase (LPCAT) and characterized two independent knockdown (KD) alleles in C. reinhardtii. The enzyme designated as C. reinhardtiiLysolipid Acyltransferase 1 (CrLAT1) has a conserved membrane-bound O-acyl transferase domain. LPCAT from Arabidopsis has a key role in deacylation of phosphatidylcholine (PC). Chlamydomonas reinhardtii, however, lacks PC, and thus we hypothesized that CrLAT1 has some other important function in major lipid flow in this organism. In the CrLAT1 KD mutants, the amount of MGMG was increased, but triacylglycerols (TAGs) were decreased. The proportion of more saturated 18:1 (9) MGDG was lower in the KD mutants than in their parental strain, CC-4533. In contrast, the proportion of MGMG has decreased in the CrLAT1 overexpression (OE) mutants, and the proportion of 18:1 (9) MGDG was higher in the OE mutants than in the empty vector control cells. Thus, CrLAT1 is involved in the recycling of MGDG in the chloroplast and maintains lipid homeostasis in C. reinhardtii.

Biochemical Characterization of Acyl-CoA: Lysophosphatidylcholine Acyltransferase (LPCAT) Enzyme from the Seeds of Salvia hispanica

Salvia hispanica (chia) is the highest reported terrestrial plant source of alpha-linolenic acid (ALA, ~ 65%), an ω-3 polyunsaturated fatty acid with numerous health benefits. The molecular basis of high ALA accumulation in chia is yet to be understood. We have identified lysophosphatidylcholine acyltransferase (LPCAT) gene from the developing seed transcriptome data of chia and carried out its biochemical characterization through heterologous expression in Saccharomyces cerevisiae. Expression profiling showed that the enzyme was active throughout the seed development, indicating a pivotal role in oil biosynthesis. The enzyme could utilize both saturated and unsaturated lysophosphatidylcholine substrates at the same rate, to synthesize phosphatidylcholine (PC). The enzyme also exhibited lysophosphatidic acid acyltransferase (LPAAT) activity, by preferring lysophosphatidic acid substrate. Substrate specificity studies showed that the enzyme preferred both monounsaturated and polyunsaturated fatty acyl CoAs over saturated CoAs. This activity may play a key role in enriching the PC fraction with polyunsaturated fatty acids (PUFAs). PUFAs present on PC can be transferred to oil through the action of other acyltransferases. Our results describe a new LPCAT enzyme that can be used to biotechnologically alter oilseed crops to incorporate more PUFA in its seed oil.