Major Bioactive Compounds from Java Plum Seeds: An Investigation of Its Extraction Procedures and Clinical Effects

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TL;DR

Java plum (Syzygium cumini) seeds contain diverse bioactive compounds including phenolic acids, flavonoids, tannins, terpenes, and alkaloids that exhibit significant pharmacological activities, particularly antidiabetic, antioxidant, anti-inflammatory, and anticancer effects. The seed's phenolic compounds and flavonoids such as quercetin, gallic acid, ellagic acid, and rutin demonstrate clinical potential through mechanisms including α-glucosidase inhibition, insulin secretion modulation, and free radical scavenging. Despite promising preclinical evidence, the review highlights the need for more randomized controlled clinical trials to translate these findings into therapeutic applications.

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**Background:** Java plum (Syzygium cumini L. Skeels), also known as black Jamun, is a medicinal plant from the Myrtaceae family, native to India and Indonesia and distributed globally in tropical and subtropical regions. The plant grows up to 30 m in height with a lifespan exceeding 100 years. All parts of the plant—seeds, leaves, fruit, bark, and wood—possess medicinal and economic value. The seeds are particularly rich in bioactive phytoconstituents including alkaloids (jambosine), flavonoids (quercetin, catechin, epicatechin, rutin, kaempferol, myricetin), phenolic acids (gallic acid, ellagic acid, ferulic acid, p-coumaric acid, chlorogenic acid, caffeic acid, syringic acid, protocatechuic acid), tannins (ellagitannins, gallotannins, corilagin), terpenes and terpenoids (betulinic acid, oleanolic acid, β-caryophyllene, β-pinene, α-pinene), and lipids (oleic acid, myristic acid, linoleic acid, palmitic acid, stearic acid). The seeds have been used in traditional Ayurvedic, Unani, and Chinese medicine for treating hyperglycemia, ulcers, dysentery, asthma, glycosuria, and bronchitis.

**Methods:** This is a narrative review article that synthesizes evidence from preclinical studies (in vitro and animal models), clinical trials, and analytical chemistry studies regarding the extraction, characterization, and pharmacological effects of bioactive compounds from Java plum seeds. The review covers extraction procedures including conventional solvent extraction, Soxhlet extraction (SJE), ultrasound-assisted extraction (UJE), microwave-assisted extraction (MJE), ultrafiltration, solid-phase microextraction, and supercritical fluid extraction. Analytical methods discussed include liquid chromatography–mass spectrometry (LC-MS), nuclear magnetic resonance (NMR) spectroscopy, high-performance liquid chromatography with diode-array detection and electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MS/MS), and gas chromatography–mass spectrometry (GC-MS).

**Key Results:** The nutritional composition of Jamun seeds varies across studies: moisture 3.21–53%, ash 1.5–21.72%, carbohydrate 6.05–89.68%, fiber 1.21–16.9%, protein 1.97–8.5%, fat 0.65–4.86%, ascorbic acid 1.84–35.75%, and iron 1.25–18.62 mg. The seed oil contains oleic acid (26.8–32.2%), myristic acid (31.7%), linoleic acid (16.1–25.2%), palmitic acid (4.7–19.9%), and stearic acid (6.4–6.5%). Total phenolic content in seeds was reported as 108.79 ± 1.0 mg/g gallic acid equivalent with antioxidant activity of 85.49 ± 0.8%. The aqueous seed extract contains approximately 21.9% gallic acid and 8.65% ellagic acid. In a randomized controlled study, 10 g/day Jamun seed powder supplementation for 90 days in type 2 diabetic patients with poor glycemic control reduced fasting plasma glucose by 30.0%, post-prandial plasma glucose by 22.0%, and HbA1c from 8.99% to 8.31%. The DPPH IC50 value for Jamun seed extract was 0.24 μg/mL, ABTS IC50 was 0.31 μg/mL, metal chelating IC50 was 48.39 μg/mL, nitric oxide radical scavenging IC50 was 37.01 μg/mL, and lipid peroxidation inhibitory activity IC50 was 5.38 μg/mL. The ethyl acetate fraction of seeds showed protein tyrosine phosphatase 1B inhibition with IC50 values of 9.37 mg/mL (valoneic acid dilactone), 28.14 mg/mL (rubuphenol), and 25.96 mg/mL (ellagic acid). Jamun seed essential oil (100 mg/kg) reduced eosinophil migration by 67% in a lipopolysaccharide-induced pleurisy model. Betulinic acid was reported safe in mice up to 500 mg/kg body weight. Seed powder at 500 and 1000 mg/kg doses showed antidiabetic effects in STZ-induced diabetic rats, and 2.5 and 5.0 g/kg seed powder caused no deaths or morbidity in subacute toxicity studies.

**Clinical Implications:** The review provides substantial preclinical evidence supporting the therapeutic potential of Jamun seed bioactive compounds, particularly for diabetes management through multiple mechanisms including α-glucosidase and α-amylase inhibition, insulin secretion stimulation, protein tyrosine phosphatase 1B inhibition, and aldose reductase inhibition. The antioxidant properties of seed phenolics and flavonoids suggest potential applications in preventing oxidative stress-related diseases including cardiovascular disease, cancer, and hepatotoxicity. Quercetin from Jamun seeds shows promise for type 2 diabetes, cardiovascular disease, osteoporosis, cancer, hypertension, and obesity, with one study showing 30 mg/kg quercetin for 14 days improved blood glucose, insulin, dyslipidemia, and oxidative stress markers in diabetic rats. However, the review emphasizes that most evidence comes from cell culture and animal studies, with limited randomized controlled clinical trials in humans. The authors note that Jamun seed powder (1–3 g/day) is traditionally recommended in Ayurveda, and no significant side effects have been reported except potential gastrointestinal distress from high-tannin bark extracts and caution advised for post-surgery patients and pregnant women due to blood sugar-lowering effects.