Extracts of Sida cordifolia contain polysaccharides possessing immunomodulatory activity and rosmarinic acid compounds with antibacterial activity.

BACKGROUND: The overuse of antibiotics has led to increased antimicrobial resistance, but plant-derived biological response modifiers represent a potential alternative to these drugs. This investigation examined the immunomodulatory and antibacterial activities of Sida cordifolia (used in ethnomedicinal systems to treat infectious disease). METHODS: Successive extractions were performed from the roots of these plants in hexane, chloroform, methanol and water. Immunomodulatory activity was determined in a series of experiments measuring the responses of splenocytes, macrophages and an in vivo model of innate immunity (Galleria mellonella). Antibacterial activity was assessed by determining minimum inhibitory/bactericidal concentrations (MIC/MBCs) for various Gram-positive and Gram-negative bacterial strains. RESULTS: Immunomodulatory activity was confined to the aqueous extract, and further fractionation and biochemical analysis yielded a highly potent polysaccharide-enriched fraction (SCAF5). SCAF5 is a complex mixture of different polysaccharides with multiple immunomodulatory effects including immune cell proliferation, antibody secretion, phagocytosis, nitric oxide production, and increased expression of pro-inflammatory cytokines. Furthermore, Galleria mellonella pre-treated with SCAF5 produced more haemocytes and were more resistant (P < 0.001) to infection with methicillin-resistant Staphylococcus aureus (MRSA) with a 98% reduction in bacterial load in pre-treated larvae compared to the negative control. The antibacterial activity of Sida cordifolia was confined to the methanolic fraction. Extensive fractionation identified two compounds, rosmarinic acid and its 4-O-ß-d-glucoside derivative, which had potent activity against Gram-positive antibiotic-resistant bacteria, including MRSA. CONCLUSIONS: Sida cordifolia counters bacterial infections through a dual mechanism, and immunomodulatory polysaccharides from this plant should be isolated and characterised to realise their potential as anti-infective agents. Such properties could be developed as an antibiotic alternative (1) in the clinic and (2) alternative growth promoter for the agri-food industry.

Self-efficacy for temptations is a better predictor of weight loss than motivation and global self-efficacy: evidence from two prospective studies among overweight/obese women at high risk of breast cancer.

OBJECTIVES: Identifying predictors of weight loss could help to triage people who will benefit most from programs and identify those who require additional support. The present research was designed to address statistical, conceptual and operational difficulties associated with the role of self-efficacy in predicting weight loss. METHODS: In Study 1, 115 dieting overweight/obese women at high risk of breast cancer were weighed and completed questionnaires assessing motivation, global self-efficacy and self-efficacy for temptations. The main outcome measure was weight, measured 3-months post-baseline. Study 2 was identical (n=107), except changes in psychological variables were computed, and used to predict weight 6-months post-baseline. RESULTS: In Study 1, self-efficacy for temptations was a significant predictor of weight loss at 3-month follow-up. In Study 2, improved self-efficacy for temptations between baseline and four-weeks was predictive of lower weight at 6 months. CONCLUSION: The key finding was that self-efficacy for temptations, as opposed to motivation and global self-efficacy, was predictive of subsequent weight loss. PRACTICE IMPLICATIONS: The implication is that augmenting dieters' capability for dealing with temptations might boost the impact of weight loss programs.