Nutritional Value, Major Chemical Compounds, and Biological Activities of Petromarula pinnata (Campanulaceae)—A Unique Nutraceutical Wild Edible Green of Crete (Greece)

Abstract

The Mediterranean diet is mostly based on high intakes of olive oil, vegetables, legumes, and fruits, with limited amounts of red meat and sweets, and is related to lower risk of cardiovascular diseases, mainly due to the health benefits of antioxidants of wild greens, fruits, and vegetables. Petromarula pinnata (L.) A. DC. is a unique (monotypic) and threatened local endemic wild edible green of Crete which is consumed raw in salads or cooked as an ingredient of the Mediterranean (Cretan) diet. In this study, we aimed to examine the nutritional value of P. pinnata with reference to wild-growing material; moreover, we investigated its chemical composition with 1H NMR spectra and its in vitro total phenolics and flavonoids (TPC, TF assays), and we evaluated the antioxidant (TAC, DPPH, and inhibition of lipid peroxidation), antimicrobial (MIC), and anti-inflammatory (inhibition of soybean lipoxygenase) in vitro activity during two different developmental stages (winter and summer collections), all referring to ex situ cultivated material (air-dried or frozen in liquid nitrogen). Our results showed that P. pinnata has good nutritional value, being rich in terpenoids and poor in phenolic compounds and flavonoids. Furthermore, the extracts showed high antioxidant activity for TAC and DPPH and some of the extracts had higher antioxidant activities than the standard compounds. The summer plant materials had higher antioxidant activity than the winter ones. The methanol/water extracts were the strongest inhibitors of the lipid peroxidation, and the methanol extracts were not found to be active. None of the extracts inhibited the soybean lipoxygenase, and thus they were devoid of anti-inflammatory activity. Finally, the extracts showed a moderate to strong bacterial inhibition. These findings consolidate that P. pinnata has a novel nutraceutical interest with high nutritional value and high antioxidant activity combined with bactericidal effect, thus updating the evaluation of its exploitation potential in the medicinal sector from below average (37%) to high (67%).